Sample records for earth orbit mission

  1. 3D Orbit Visualization for Earth-Observing Missions (United States)

    Jacob, Joseph C.; Plesea, Lucian; Chafin, Brian G.; Weiss, Barry H.


    This software visualizes orbit paths for the Orbiting Carbon Observatory (OCO), but was designed to be general and applicable to any Earth-observing mission. The software uses the Google Earth user interface to provide a visual mechanism to explore spacecraft orbit paths, ground footprint locations, and local cloud cover conditions. In addition, a drill-down capability allows for users to point and click on a particular observation frame to pop up ancillary information such as data product filenames and directory paths, latitude, longitude, time stamp, column-average dry air mole fraction of carbon dioxide, and solar zenith angle. This software can be integrated with the ground data system for any Earth-observing mission to automatically generate daily orbit path data products in Google Earth KML format. These KML data products can be directly loaded into the Google Earth application for interactive 3D visualization of the orbit paths for each mission day. Each time the application runs, the daily orbit paths are encapsulated in a KML file for each mission day since the last time the application ran. Alternatively, the daily KML for a specified mission day may be generated. The application automatically extracts the spacecraft position and ground footprint geometry as a function of time from a daily Level 1B data product created and archived by the mission s ground data system software. In addition, ancillary data, such as the column-averaged dry air mole fraction of carbon dioxide and solar zenith angle, are automatically extracted from a Level 2 mission data product. Zoom, pan, and rotate capability are provided through the standard Google Earth interface. Cloud cover is indicated with an image layer from the MODIS (Moderate Resolution Imaging Spectroradiometer) aboard the Aqua satellite, which is automatically retrieved from JPL s OnEarth Web service.

  2. Innovations in mission architectures for exploration beyond low Earth orbit (United States)

    Cooke, D. R.; Joosten, B. J.; Lo, M. W.; Ford, K. M.; Hansen, R. J.


    Through the application of advanced technologies and mission concepts, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to science driven; technology enabled human and robotic exploration. Numbers and masses of vehicles required are greatly reduced, yet the pursuit of a broader range of science objectives is enabled. The scope of human missions considered range from the assembly and maintenance of large aperture telescopes for emplacement at the Sun-Earth libration point L2, to human missions to asteroids, the moon and Mars. The vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities, which allows for future decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration. c2003 American Institute of Aeronautics and Astronautics. Published by Elsevier Science Ltd. All rights reserved.

  3. Orbit Determination Error Analysis Results for the Triana Sun-Earth L2 Libration Point Mission (United States)

    Marr, G.


    Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination error analysis results are presented for all phases of the Triana Sun-Earth L1 libration point mission and for the science data collection phase of a future Sun-Earth L2 libration point mission. The Triana spacecraft was nominally to be released by the Space Shuttle in a low Earth orbit, and this analysis focuses on that scenario. From the release orbit a transfer trajectory insertion (TTI) maneuver performed using a solid stage would increase the velocity be approximately 3.1 km/sec sending Triana on a direct trajectory to its mission orbit. The Triana mission orbit is a Sun-Earth L1 Lissajous orbit with a Sun-Earth-vehicle (SEV) angle between 4.0 and 15.0 degrees, which would be achieved after a Lissajous orbit insertion (LOI) maneuver at approximately launch plus 6 months. Because Triana was to be launched by the Space Shuttle, TTI could potentially occur over a 16 orbit range from low Earth orbit. This analysis was performed assuming TTI was performed from a low Earth orbit with an inclination of 28.5 degrees and assuming support from a combination of three Deep Space Network (DSN) stations, Goldstone, Canberra, and Madrid and four commercial Universal Space Network (USN) stations, Alaska, Hawaii, Perth, and Santiago. These ground stations would provide coherent two-way range and range rate tracking data usable for orbit determination. Larger range and range rate errors were assumed for the USN stations. Nominally, DSN support would end at TTI+144 hours assuming there were no USN problems. Post-TTI coverage for a range of TTI longitudes for a given nominal trajectory case were analyzed. The orbit determination error analysis after the first correction maneuver would be generally applicable to any libration point mission utilizing a direct trajectory.

  4. Early Mission Orbit Determination Error Analysis Results for Low-Earth Orbiting Missions using TDRSS Differenced One-way Doppler Tracking Data (United States)

    Marr, Greg C.


    Differencing multiple, simultaneous Tracking and Data Relay Satellite System (TDRSS) one-way Doppler passes can yield metric tracking data usable for orbit determination for (low-cost) spacecraft which do not have TDRSS transponders or local oscillators stable enough to allow the one-way TDRSS Doppler tracking data to be used for early mission orbit determination. Orbit determination error analysis results are provided for low Earth orbiting spacecraft for various early mission tracking scenarios.

  5. Innovations in Mission Architectures for Human and Robotic Exploration Beyond Low Earth Orbit (United States)

    Cooke, Douglas R.; Joosten, B. Kent; Lo, Martin W.; Ford, Ken; Hansen, Jack


    Through the application of advanced technologies, mission concepts, and new ideas in combining capabilities, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to discovery driven, technology enabled exploration. Numbers and masses of vehicles required are greatly reduced, yet enable the pursuit of a broader range of objectives. The scope of missions addressed range from the assembly and maintenance of arrays of telescopes for emplacement at the Earth-Sun L2, to Human missions to asteroids, the moon and Mars. Vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities; allowing for decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration.

  6. Radiation Information for Designing and Interpreting Biological Experiments Onboard Missions Beyond Low Earth Orbit (United States)

    Straume, T.; Slaba, T.; Bhattacharya, S.; Braby, L. A.


    There is growing interest in flying biological experiments beyond low-Earth orbit (LEO) to measure biological responses potentially relevant to those expected during a human mission to Mars. Such experiments could be payloads onboard precursor missions, including unmanned private-public partnerships, as well as small low-cost spacecraft (satellites) designed specifically for biosentinel type missions. Designing such experiments requires knowledge of the radiation environment and its interactions with both the spacecraft and the experimental payload. Information is provided here that is useful for designing such experiments.

  7. Essentials for Team Based Rehearsals and the Differences Between Earth Orbiting and Deep Space Missions (United States)

    Gomez-Rosa, Carlos; Cifuentes, Juan; Wasiak, Francis; Alfonzo, Agustin


    The mission readiness environment is where spacecraft and ground systems converge to form the entire as built flight system for the final phase of operationally-themed testing. For most space missions, this phase starts between nine to twelve months prior to the planned launch. In the mission readiness environment, the goal is to perform sufficient testing to exercise the flight teams and systems through all mission phases in order to demonstrate that all elements are ready to support. As part of the maturation process, a mission rehearsal program is introduced to focus on team processes within the final flight system, in a more realistic operational environment. The overall goal for a mission rehearsal program is to: 1) ensure all flight system elements are able to meet mission objectives as a cohesive team; 2) reduce the risk in space based operations due to deficiencies in people, processes, procedures, or systems; and 3) instill confidence in the teams that will execute these first time flight activities. A good rehearsal program ensures critical events are exercised, discovers team or flight system nuances whose impact were previously unknown, and provides a real-time environment in which to interact with the various teams and systems. For flight team members, the rehearsal program provides experience and training in the event of planned (or unplanned) flight contingencies. To preserve the essence for team based rehearsals, this paper will explore the important elements necessary for a successful rehearsal program, document differences driven by Earth Orbiting (Aqua, Aura, Suomi-National Polar-orbiting Partnership (NPP)) and Deep Space missions (New Horizons, Mars Atmosphere and Volatile EvolutioN (MAVEN)) and discuss common challenges to both mission types. In addition, large scale program considerations and enhancements or additional steps for developing a rehearsal program will also be considered. For NASA missions, the mission rehearsal phase is a key

  8. Cost-effective technology advancement directions for electric propulsion transportation systems in earth-orbital missions (United States)

    Regetz, J. D., Jr.; Terwilliger, C. H., Jr.


    This paper presents the results of a study to determine the directions that electric propulsion technology should take to meet the primary propulsion requirements for earth-orbital missions of the next three decades in the most cost-effective manner. Discussed are the mission set requirements, state-of-the-art electric propulsion technology and the baseline system characterized by it, adequacy of the baseline system to meet the mission set requirements, cost-optimum electric propulsion system characteristics for the mission set, and sensitivities of mission costs and design points to system-level electric propulsion parameters. It is found that the efficiency-specific impulse characteristic generally has a more significant impact on overall costs than specific masses or costs of propulsion and power systems.

  9. Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions (United States)

    Israel, David J.


    The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

  10. Mass driver reaction engine characteristics and performance in earth orbital transfer missions (United States)

    Snow, W. R.; Dunbar, R. S.


    Configurations of a typical mass driver reaction engine (MDRE) are presented and its use for delivery of payloads to geosynchronous orbit (GEO) from low earth orbit (LEO) is discussed. Basic rocket equations are developed for LEO to GEO round-trip missions using a single exhaust velocity. It is shown that exhaust velocities in the 5-10 km/sec range (specific impulse of 500-1000 sec) are well suited for mass drivers, minimizing the overall cost of missions. Payload delivery rate fractions show that there is little to be gained by stretching out LEO to GEO transfer times from 90 to 180 days. It therefore pays to use the shorter trip time, approximately doubling the amount of delivered payload during any fixed time of use of the MDRE.

  11. A Framework for Orbital Performance Evaluation in Distributed Space Missions for Earth Observation (United States)

    Nag, Sreeja; LeMoigne-Stewart, Jacqueline; Miller, David W.; de Weck, Olivier


    Distributed Space Missions (DSMs) are gaining momentum in their application to earth science missions owing to their unique ability to increase observation sampling in spatial, spectral and temporal dimensions simultaneously. DSM architectures have a large number of design variables and since they are expected to increase mission flexibility, scalability, evolvability and robustness, their design is a complex problem with many variables and objectives affecting performance. There are very few open-access tools available to explore the tradespace of variables which allow performance assessment and are easy to plug into science goals, and therefore select the most optimal design. This paper presents a software tool developed on the MATLAB engine interfacing with STK, for DSM orbit design and selection. It is capable of generating thousands of homogeneous constellation or formation flight architectures based on pre-defined design variable ranges and sizing those architectures in terms of predefined performance metrics. The metrics can be input into observing system simulation experiments, as available from the science teams, allowing dynamic coupling of science and engineering designs. Design variables include but are not restricted to constellation type, formation flight type, FOV of instrument, altitude and inclination of chief orbits, differential orbital elements, leader satellites, latitudes or regions of interest, planes and satellite numbers. Intermediate performance metrics include angular coverage, number of accesses, revisit coverage, access deterioration over time at every point of the Earth's grid. The orbit design process can be streamlined and variables more bounded along the way, owing to the availability of low fidelity and low complexity models such as corrected HCW equations up to high precision STK models with J2 and drag. The tool can thus help any scientist or program manager select pre-Phase A, Pareto optimal DSM designs for a variety of science

  12. High Cycle Life, Low Temperature Lithium Ion Battery for Earth Orbiting and Planetary Missions Project (United States)

    National Aeronautics and Space Administration — NASA requires development of advanced rechargeable electrochemical battery systems for lithium ion batteries to support orbiting spacecraft and planetary missions....

  13. A Wide Field Auroral Imager (WFAI for low Earth orbit missions

    Directory of Open Access Journals (Sweden)

    N. P. Bannister


    Full Text Available A comprehensive understanding of the solar wind interaction with Earth's coupled magnetosphere-ionosphere system requires an ability to observe the charged particle environment and auroral activity from the same platform, generating particle and photon image data which are matched in time and location. While unambiguous identification of the particles giving rise to the aurora requires a Low Earth Orbit satellite, obtaining adequate spatial coverage of aurorae with the relatively limited field of view of current space bourne auroral imaging systems requires much higher orbits. A goal for future satellite missions, therefore, is the development of compact, wide field-of-view optics permitting high spatial and temporal resolution ultraviolet imaging of the aurora from small spacecraft in low polar orbit. Microchannel plate optics offer a method of achieving the required performance. We describe a new, compact instrument design which can observe a wide field-of-view with the required spatial resolution. We report the focusing of 121.6 nm radiation using a spherically-slumped, square-pore microchannel plate with a focal length of 32 mm and an F number of 0.7. Measurements are compared with detailed ray-trace simulations of imaging performance. The angular resolution is 2.7±0.2° for the prototype, corresponding to a footprint ~33 km in diameter for an aurora altitude of 110 km and a spacecraft altitude of 800 km. In preliminary analysis, a more recent optic has demonstrated a full width at half maximum of 5.0±0.3 arcminutes, corresponding to a footprint of ~1 km from the same spacecraft altitude. We further report the imaging properties of a convex microchannel plate detector with planar resistive anode readout; this detector, whose active surface has a radius of curvature of only 100 mm, is shown to meet the spatial resolution and sensitivity requirements of the new wide field auroral imager (WFAI.

  14. Comparison of technologies for deorbiting spacecraft from low-earth-orbit at end of mission (United States)

    Sánchez-Arriaga, G.; Sanmartín, J. R.; Lorenzini, E. C.


    An analytical comparison of four technologies for deorbiting spacecraft from Low-Earth-Orbit at end of mission is presented. Basic formulas based on simple physical models of key figures of merit for each device are found. Active devices - rockets and electrical thrusters - and passive technologies - drag augmentation devices and electrodynamic tethers - are considered. A basic figure of merit is the deorbit device-to-spacecraft mass ratio, which is, in general, a function of environmental variables, technology development parameters and deorbit time. For typical state-of-the-art values, equal deorbit time, middle inclination and initial altitude of 850 km, the analysis indicates that tethers are about one and two orders of magnitude lighter than active technologies and drag augmentation devices, respectively; a tether needs a few percent mass-ratio for a deorbit time of a couple of weeks. For high inclination, the performance drop of the tether system is moderate: mass ratio and deorbit time increase by factors of 2 and 4, respectively. Besides collision risk with other spacecraft and system mass considerations, such as main driving factors for deorbit space technologies, the analysis addresses other important constraints, like deorbit time, system scalability, manoeuver capability, reliability, simplicity, attitude control requirement, and re-entry and multi-mission capability (deorbit and re-boost) issues. The requirements and constraints are used to make a critical assessment of the four technologies as functions of spacecraft mass and initial orbit (altitude and inclination). Emphasis is placed on electrodynamic tethers, including the latest advances attained in the FP7/Space project BETs. The superiority of tape tethers as compared to round and multi-line tethers in terms of deorbit mission performance is highlighted, as well as the importance of an optimal geometry selection, i.e. tape length, width, and thickness, as function of spacecraft mass and initial

  15. Single Event Effects Testing For Low Earth Orbit Missions with Neutrons (United States)

    Reddell, Brandon; O'Neill, Pat; Bailey, Chuck; Nguyen, Kyson


    Neutrons can effectively be used to screen electronic parts intended to be used in Low Earth Orbit. This paper compares neutron with proton environments in spacecraft and discusses recent comparison testing.

  16. Observing the Polar Upper Atmosphere from Low Earth Orbit: Challenges, Opportunities, and New Missions (United States)

    Paxton, L. J.


    instrument's band pass. From low Earth orbit, such as that of the US Air Force Defense Meteorological Satellite Program (DMSP) satellites that operate at 830 km altitude, or the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission at 625 km, other approaches have to be adopted to maximize the amount of the aurora that can be imaged. The Special Sensor Ultraviolet Spectrographic Imager (SSUSI) on DMSP and the Global Ultraviolet Imager (GUVI) on TIMED are examples of an approach that seeks to maximize auroral coverage, responsivity, spectral "purity", and number of simultaneous wavelengths covered. Each general class of sensor has its advantages and issues. In combination, HEO and LEO sensors provide powerful tools for probing the Earth's atmosphere, particularly the polar upper atmosphere and auroral phenomena. In this talk I will summarize the status of the SSUSI and GUVI projects, their data products, how and when these validated data products will be made available, and plans for coordinated observations with ground sites and other space assets. These new sensors, that should fly begining this summer and will provide continuous auroral imagery from LEO for the next ten years, meet their own objectives as well as providing key measurements for the Sun-Earth Connections and Living With a Star Programs.

  17. Orbit Determination (OD) Error Analysis Results for the Triana Sun-Earth L1 Libration Point Mission and for the Fourier Kelvin Stellar Interferometer (FKSI) Sun-Earth L2 Libration Point Mission Concept (United States)

    Marr, Greg C.


    The Triana spacecraft was designed to be launched by the Space Shuttle. The nominal Triana mission orbit will be a Sun-Earth L1 libration point orbit. Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination (OD) error analysis results are presented for all phases of the Triana mission from the first correction maneuver through approximately launch plus 6 months. Results are also presented for the science data collection phase of the Fourier Kelvin Stellar Interferometer Sun-Earth L2 libration point mission concept with momentum unloading thrust perturbations during the tracking arc. The Triana analysis includes extensive analysis of an initial short arc orbit determination solution and results using both Deep Space Network (DSN) and commercial Universal Space Network (USN) statistics. These results could be utilized in support of future Sun-Earth libration point missions.

  18. Abort Options for Human Missions to Earth-Moon Halo Orbits (United States)

    Jesick, Mark C.


    Abort trajectories are optimized for human halo orbit missions about the translunar libration point (L2), with an emphasis on the use of free return trajectories. Optimal transfers from outbound free returns to L2 halo orbits are numerically optimized in the four-body ephemeris model. Circumlunar free returns are used for direct transfers, and cislunar free returns are used in combination with lunar gravity assists to reduce propulsive requirements. Trends in orbit insertion cost and flight time are documented across the southern L2 halo family as a function of halo orbit position and free return flight time. It is determined that the maximum amplitude southern halo incurs the lowest orbit insertion cost for direct transfers but the maximum cost for lunar gravity assist transfers. The minimum amplitude halo is the most expensive destination for direct transfers but the least expensive for lunar gravity assist transfers. The on-orbit abort costs for three halos are computed as a function of abort time and return time. Finally, an architecture analysis is performed to determine launch and on-orbit vehicle requirements for halo orbit missions.

  19. Automatic trajectory planning for low-thrust active removal mission in low-earth orbit (United States)

    Di Carlo, Marilena; Romero Martin, Juan Manuel; Vasile, Massimiliano


    In this paper two strategies are proposed to de-orbit up to 10 non-cooperative objects per year from the region within 800 and 1400 km altitude in Low Earth Orbit (LEO). The underlying idea is to use a single servicing spacecraft to de-orbit several objects applying two different approaches. The first strategy is analogous to the Traveling Salesman Problem: the servicing spacecraft rendezvous with multiple objects in order to physically attach a de-orbiting kit that reduces the perigee of the orbit. The second strategy is analogous to the Vehicle Routing Problem: the servicing spacecraft rendezvous and docks with an object, spirals it down to a lower altitude orbit, undocks, and then spirals up to the next target. In order to maximise the number of de-orbited objects with minimum propellant consumption, an optimal sequence of targets is identified using a bio-inspired incremental automatic planning and scheduling discrete optimisation algorithm. The optimisation of the resulting sequence is realised using a direct transcription method based on an asymptotic analytical solution of the perturbed Keplerian motion. The analytical model takes into account the perturbations deriving from the J2 gravitational effect and the atmospheric drag.

  20. Life Support and Habitation Systems: Crew Support and Protection for Human Exploration Missions Beyond Low Earth Orbit (United States)

    Barta, Daniel J.; McQuillan, Jeffrey


    The National Aeronautics and Space Administration (NASA) has recently expanded its mission set for possible future human exploration missions. With multiple options there is interest in identifying technology needs across these missions to focus technology investments. In addition to the Moon and other destinations in cis-lunar space, other destinations including Near Earth Objects and Mars have been added for consideration. Recently, technology programs and projects have been re-organizing to better meet the Agency s strategic goals and address needs across these potential future missions. Life Support and Habitation Systems (LSHS) is one of 10 Foundational Domains as part of the National Aeronautics and Space Administration s Exploration Technology Development Program. The chief goal of LSHS is to develop and mature advanced technologies to sustain human life on missions beyond Low Earth Orbit (LEO) to increase reliability, reduce dependency on resupply and increase vehicle self-sufficiency. For long duration exploration missions, further closure of life support systems is of interest. Focus includes key technologies for atmosphere revitalization, water recovery, waste management, thermal control and crew accommodations. Other areas of focus include technologies for radiation protection, environmental monitoring and fire protection. The aim is to recover additional consumable mass, reduce requirements for power, volume, heat rejection, crew involvement, and meet exploration vehicle requirements. This paper provides a brief description of the LSHS Foundational Domain as defined for fiscal year 2011.

  1. A Neptune Orbiter Mission (United States)

    Wallace, R. A.; Spilker, T. R.


    This paper describes the results of new analyses and mission/system designs for a low cost Neptune Orbiter mission. Science and measurement objectives, instrumentation, and mission/system design options are described and reflect an aggressive approach to the application of new advanced technologies expected to be available and developed over the next five to ten years.

  2. Properties of an Earth-like planet orbiting a Sun-like star: Earth observed by the EPOXI mission. (United States)

    Livengood, Timothy A; Deming, L Drake; A'hearn, Michael F; Charbonneau, David; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Meadows, Victoria S; Robinson, Tyler D; Seager, Sara; Wellnitz, Dennis D


    NASA's EPOXI mission observed the disc-integrated Earth and Moon to test techniques for reconnoitering extrasolar terrestrial planets, using the Deep Impact flyby spacecraft to observe Earth at the beginning and end of Northern Hemisphere spring, 2008, from a range of ∼1/6 to 1/3 AU. These observations furnish high-precision and high-cadence empirical photometry and spectroscopy of Earth, suitable as "ground truth" for numerically simulating realistic observational scenarios for an Earth-like exoplanet with finite signal-to-noise ratio. Earth was observed at near-equatorial sub-spacecraft latitude on 18-19 March, 28-29 May, and 4-5 June (UT), in the range of 372-4540 nm wavelength with low visible resolving power (λ/Δλ=5-13) and moderate IR resolving power (λ/Δλ=215-730). Spectrophotometry in seven filters yields light curves at ∼372-948 nm filter-averaged wavelength, modulated by Earth's rotation with peak-to-peak amplitude of ≤20%. The spatially resolved Sun glint is a minor contributor to disc-integrated reflectance. Spectroscopy at 1100-4540 nm reveals gaseous water and carbon dioxide, with minor features of molecular oxygen, methane, and nitrous oxide. One-day changes in global cloud cover resulted in differences between the light curve beginning and end of ≤5%. The light curve of a lunar transit of Earth on 29 May is color-dependent due to the Moon's red spectrum partially occulting Earth's relatively blue spectrum. The "vegetation red edge" spectral contrast observed between two long-wavelength visible/near-IR bands is ambiguous, not clearly distinguishing between the verdant Earth diluted by cloud cover versus the desolate mineral regolith of the Moon. Spectrophotometry in at least one other comparison band at short wavelength is required to distinguish between Earth-like and Moon-like surfaces in reconnaissance observations. However, measurements at 850 nm alone, the high-reflectance side of the red edge, could be sufficient to

  3. NEUDOSE: A CubeSat Mission for Dosimetry of Charged Particles and Neutrons in Low-Earth Orbit. (United States)

    Hanu, A R; Barberiz, J; Bonneville, D; Byun, S H; Chen, L; Ciambella, C; Dao, E; Deshpande, V; Garnett, R; Hunter, S D; Jhirad, A; Johnston, E M; Kordic, M; Kurnell, M; Lopera, L; McFadden, M; Melnichuk, A; Nguyen, J; Otto, A; Scott, R; Wagner, D L; Wiendels, M


    During space missions, astronauts are exposed to a stream of energetic and highly ionizing radiation particles that can suppress immune system function, increase cancer risks and even induce acute radiation syndrome if the exposure is large enough. As human exploration goals shift from missions in low-Earth orbit (LEO) to long-duration interplanetary missions, radiation protection remains one of the key technological issues that must be resolved. In this work, we introduce the NEUtron DOSimetry & Exploration (NEUDOSE) CubeSat mission, which will provide new measurements of dose and space radiation quality factors to improve the accuracy of cancer risk projections for current and future space missions. The primary objective of the NEUDOSE CubeSat is to map the in situ lineal energy spectra produced by charged particles and neutrons in LEO where most of the preparatory activities for future interplanetary missions are currently taking place. To perform these measurements, the NEUDOSE CubeSat is equipped with the Charged & Neutral Particle Tissue Equivalent Proportional Counter (CNP-TEPC), an advanced radiation monitoring instrument that uses active coincidence techniques to separate the interactions of charged particles and neutrons in real time. The NEUDOSE CubeSat, currently under development at McMaster University, provides a modern approach to test the CNP-TEPC instrument directly in the unique environment of outer space while simultaneously collecting new georeferenced lineal energy spectra of the radiation environment in LEO.

  4. ISECG Mission Scenarios and Their Role in Informing Next Steps for Human Exploration Beyond Low Earth Orbit (United States)

    Culbert, Christopher J.; Mongrard, Olivier; Satoh, Naoki; Goodliff, Kandyce; Seaman, Calvin H.; Troutman, Patrick; Martin, Eric


    The International Space Exploration Coordination Group (ISECG) was established in response to The Global Exploration Strategy (GES): The Framework for Coordination developed by fourteen space agencies* and released in May 2007. This GES Framework Document recognizes that preparing for human space exploration is a stepwise process, starting with basic knowledge and culminating in a sustained human presence in deep space. ISECG has developed several optional global exploration mission scenarios enabling the phased transition from human operations in Low Earth Orbit (LEO) and utilization of the International Space Station (ISS) to human missions beyond LEO leading ultimately to human missions to cis-lunar space, the Moon, Near Earth Asteroids, Mars and its environs. Mission scenarios provide the opportunity for judging various exploration approaches in a manner consistent with agreed international goals and strategies. Each ISECG notional mission scenario reflects a series of coordinated human and robotic exploration missions over a 25-year horizon. Mission scenarios are intended to provide insights into next steps for agency investments, following on the success of the ISS. They also provide a framework for advancing the definition of Design Reference Missions (DRMs) and the concepts for capabilities contained within. Each of the human missions contained in the scenarios has been characterized by a DRM which is a top level definition of mission sequence and the capabilities needed to execute that mission. While DRMs are generally destination focused, they will comprise capabilities which are reused or evolved from capabilities used at other destinations. In this way, an evolutionary approach to developing a robust set of capabilities to sustainably explore our solar system is defined. Agencies also recognize that jointly planning for our next steps, building on the accomplishments of ISS, is important to ensuring the robustness and sustainability of any human

  5. Introducing Earth's Orbital Eccentricity (United States)

    Oostra, Benjamin


    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  6. The effect of proton radiation on the EMCCD for a low Earth orbit satellite mission (United States)

    Smith, Ken; Daigle, Olivier; Scott, Alan; Piche, Louis; Hudson, Danya


    We report on the proton radiation effects on a 1k x 1k e2v EMCCD utilized in the Nüvü EM N2 1024 camera. Radiation testing was performed at the TRIUMF Proton Irradiation Facility in Canada, where the e2v CCD201-20 EMCCD received a 105 MeV proton fluence up to 5.2x109 protons/cm2, emulating a 1 year's radiation dose of solar protons in low earth orbit with nominal shielding that would be expected from a small or microsatellite. The primary space-based application is for Space Situational Awareness (SSA), where a small telescope images faint orbiting Resident Space Objects (RSOs) on the EMCCD, resulting in faint streaks at the photon level of signal in the images. Of particular concern is the effect of proton radiation on low level CTE, where very low level signals could be severely impaired if not lost. Although other groups have reported on the characteristics of irradiated EMCCDs, their CTE results are not portable to this application. To understand the real impact of proton irradiation the device must be tested under realistic operating conditions with representative backgrounds, clock periods, and signal levels. Testing was performed both in the laboratory and under a night sky on the ground in order to emulate a complex star background environment containing RSOs. The degradation is presented and mitigation techniques are proposed. As compared to conventional CCDs, the EMCCD with high gain allows faint and moving RSOs to be detected with a relatively small telescope aperture, at improved signal to noise ratio at high frame rates. This allows the satellite platform to take sharp images immediately upon slewing to the target without the need for complex and relatively slow attitude stabilization systems.

  7. Apollo guidance, navigation and control: Guidance system operations plan for manned CM earth orbital and lunar missions using Program COLOSSUS 3. Section 3: Digital autopilots (revision 14) (United States)


    Digital autopilots for the manned command module earth orbital and lunar missions using program COLOSSUS 3 are discussed. Subjects presented are: (1) reaction control system digital autopilot, (2) thrust vector control autopilot, (3) entry autopilot and mission control programs, (4) takeover of Saturn steering, and (5) coasting flight attitude maneuver routine.

  8. A MATLAB based Distributed Real-time Simulation of Lander-Orbiter-Earth Communication for Lunar Missions (United States)

    Choudhury, Diptyajit; Angeloski, Aleksandar; Ziah, Haseeb; Buchholz, Hilmar; Landsman, Andre; Gupta, Amitava; Mitra, Tiyasa

    Lunar explorations often involve use of a lunar lander , a rover [1],[2] and an orbiter which rotates around the moon with a fixed radius. The orbiters are usually lunar satellites orbiting along a polar orbit to ensure visibility with respect to the rover and the Earth Station although with varying latency. Communication in such deep space missions is usually done using a specialized protocol like Proximity-1[3]. MATLAB simulation of Proximity-1 have been attempted by some contemporary researchers[4] to simulate all features like transmission control, delay etc. In this paper it is attempted to simulate, in real time, the communication between a tracking station on earth (earth station), a lunar orbiter and a lunar rover using concepts of Distributed Real-time Simulation(DRTS).The objective of the simulation is to simulate, in real-time, the time varying communication delays associated with the communicating elements with a facility to integrate specific simulation modules to study different aspects e.g. response due to a specific control command from the earth station to be executed by the rover. The hardware platform comprises four single board computers operating as stand-alone real time systems (developed by MATLAB xPC target and inter-networked using UDP-IP protocol). A time triggered DRTS approach is adopted. The earth station, the orbiter and the rover are programmed as three standalone real-time processes representing the communicating elements in the system. Communication from one communicating element to another constitutes an event which passes a state message from one element to another, augmenting the state of the latter. These events are handled by an event scheduler which is the fourth real-time process. The event scheduler simulates the delay in space communication taking into consideration the distance between the communicating elements. A unique time synchronization algorithm is developed which takes into account the large latencies in space

  9. Lissajous Orbit Control for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission (United States)

    Roberts, Craig; Case, Sarah; Reagoso, John


    DSCOVR Lissajous Orbit sized such that orbit track never extends beyond 15 degrees from Earth-Sun line (as seen from Earth). Requiring delta-V maneuvers, control orbit to obey a Solar Exclusion Zone (SEZ) cone of half-angle 4 degrees about the Earth-Sun line. Spacecraft should never be less than 4 degrees from solar center as seen from Earth. Following Lissajous Orbit Insertion (LOI), DSCOVR should be in an opening phase that just skirts the 4-degree SEZ. Maximizes time to the point where a closing Lissajous will require avoidance maneuvers to keep it out of the SEZ. Station keeping maneuvers should take no more than 15 minutes.

  10. Guiding Requirements for Designing Life Support System Architectures for Crewed Exploration Missions Beyond Low-Earth Orbit (United States)

    Perry, Jay L.; Sargusingh, Miriam J.; Toomarian, Nikzad


    The National Aeronautics and Space Administration's (NASA) technology development roadmaps provide guidance to focus technological development in areas that enable crewed exploration missions beyond low-Earth orbit. Specifically, the technology area roadmap on human health, life support and habitation systems describes the need for life support system (LSS) technologies that can improve reliability and in-flight maintainability within a minimally-sized package while enabling a high degree of mission autonomy. To address the needs outlined by the guiding technology area roadmap, NASA's Advanced Exploration Systems (AES) Program has commissioned the Life Support Systems (LSS) Project to lead technology development in the areas of water recovery and management, atmosphere revitalization, and environmental monitoring. A notional exploration LSS architecture derived from the International Space has been developed and serves as the developmental basis for these efforts. Functional requirements and key performance parameters that guide the exploration LSS technology development efforts are presented and discussed. Areas where LSS flight operations aboard the ISS afford lessons learned that are relevant to exploration missions are highlighted.

  11. High-precision repeat-groundtrack orbit design and maintenance for Earth observation missions (United States)

    He, Yanchao; Xu, Ming; Jia, Xianghua; Armellin, Roberto


    The focus of this paper is the design and station keeping of repeat-groundtrack orbits for Sun-synchronous satellites. A method to compute the semimajor axis of the orbit is presented together with a station-keeping strategy to compensate for the perturbation due to the atmospheric drag. The results show that the nodal period converges gradually with the increase of the order used in the zonal perturbations up to J_{15}. A differential correction algorithm is performed to obtain the nominal semimajor axis of the reference orbit from the inputs of the desired nodal period, eccentricity, inclination and argument of perigee. To keep the satellite in the proximity of the repeat-groundtrack condition, a practical orbit maintenance strategy is proposed in the presence of errors in the orbital measurements and control, as well as in the estimation of the semimajor axis decay rate. The performance of the maintenance strategy is assessed via the Monte Carlo simulation and the validation in a high fidelity model. Numerical simulations substantiate the validity of proposed mean-elements-based orbit maintenance strategy for repeat-groundtrack orbits.

  12. A Cooperative Multi-Satellite Mission for Controlled Active Debris Removal from Low Earth Orbit (United States)


    area for components and structural fragments surviving reentry shall not exceed 1 in 10,000.” Bon- nal et al. [13] quantify the risks presented by...engine survive reentry. The resulting casualty area and kinetic energy at impact for the propellant tank are 10.15 m2 and 25.9 kJ, and for the complex het- erogeneous multi-satellite mission design. From the authors experience in formation flying mission design [59], [60], [61], [62

  13. Mars Telecom Orbiter mission operations concepts (United States)

    Deutsch, Marie-Jose; Komarek, Tom; Lopez, Saturnino; Townes, Steve; Synnott, Steve; Austin, Richard; Guinn, Joe; Varghese, Phil; Edwards, Bernard; Bondurant, Roy; hide


    The Mars Telecom Orbiter (MTO) relay capability enables next decadal missions at Mars, collecting gigabits of data a day to be relayed back at speeds exceeding 4 Mbps and it facilitates small missions whose limited resources do not permit them to have a direct link to Earth.

  14. Optimal parking orbits for manned Mars missions (United States)

    Cupples, Michael L.; Nordwall, Jill A.

    This paper summarizes a Mars parking orbit optimization effort. This parking orbit study includes the selection of optimal elliptic Mars parking orbits that meet mission constraints and that include pertinent apsidal misalignment losses. Mars missions examined are for the opportunity years of 2014, 2016, and 2018. For these mission opportunities, it is shown that the optimal parking orbits depend on the year that the mission occurs and are coupled with the outbound, Mars stay, and return phases of the mission. Constraints included in the parking orbit optimization process are periapsis lighting angle (related to a daylight landing requirement), periapsis latitude (related to a landing latitude range requirement) and the vehicle Trans-Earth-Injection stage mass. Also, effects of mission abort requirements on optimal parking orbits are investigated. Off-periapsis maneuvers for Mars orbit capture were found to be cost effective in reducing the mission delta-V for the 2016 abort from Mars capture scenario. The total capture and departure delta-V was `split' between the capture maneuver and the departure maneuver to reduce the 2016 Mars departure delta-V to below the level of the corresponding stage of the 2014 baseline mission. Landing results are provided that show Mars landing site access from the optimal elliptic parking orbits for Mars excursion vehicles with low (0.2) and high (1.3 and 1.6) lift to drag ratio.

  15. ORION: A Supersynchronous Transfer Orbit mission (United States)

    Walters, I. M.; Baker, J. F.; Shurmer, I. M.


    ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

  16. ORION: A Supersynchronous Transfer Orbit mission (United States)

    Walters, I. M.; Baker, J. F.; Shurmer, I. M.


    ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

  17. Getting Out of Orbit: Water Recycling Requirements and Technology Needs for Long Duration Missions Away from Earth (United States)

    Barta, Daniel J.


    Deep-space crewed missions will not have regular access to the Earth's resources or the ability to rapidly return to Earth if a system fails. As crewed missions extend farther from Earth for longer periods, habitation systems must become more self-sufficient and reliable for safe, healthy, and sustainable human exploration. For human missions to Mars, Environmental Control and Life Support Systems (ECLSS) must be able operate for up to 1,100 days with minimal spares and consumables. These missions will require capabilities to more fully recycle atmospheric gases and wastewater to substantially reduce mission costs. Even with relatively austere requirements for use, water represents one of the largest consumables by mass. Systems must be available to extract and recycle water from all sources of waste. And given that there will be no opportunity to send samples back to Earth for analysis, analytical measurements will be limited to monitoring hardware brought on board the spacecraft. The Earth Reliant phase of NASA's exploration strategy includes leveraging the International Space Station (ISS) to demonstrate advanced capabilities for a robust and reliable ECLSS. The ISS Water Recovery System (WRS) includes a Urine Processor Assembly (UPA) for distillation and recovery of water from urine and a Water Processor Assembly (WPA) to process humidity condensate and urine distillate into potable water. Possible enhancements to more fully "close the water loop" include recovery of water from waste brines and solid wastes. A possible game changer is the recovery of water from local planetary resources through use of In Situ Resource Utilization (ISRU) technologies. As part of the development and demonstration sequence, NASA intends to utilize cis-Lunar space as a Proving Ground to verify systems for deep space habitation by conducting extended duration missions to validate our readiness for Mars.

  18. ARTEMIS: The First Mission to the Lunar Libration Orbits (United States)

    Woodward, Mark; Folta, David; Woodfork, Dennis


    The ARTEMIS mission will be the first to navigate to and perform stationkeeping operations around the Earth-Moon L1 and L2 Lagrangian points. The NASA Goddard Space Flight Center (GSFC) has previous mission experience flying in the Sun-Earth L1 (SOHO, ACE, WIND, ISEE-3) and L2 regimes (WMAP) and have maintained these spacecraft in libration point orbits by performing regular orbit stationkeeping maneuvers. The ARTEMIS mission will build on these experiences, but stationkeeping in Earth-Moon libration orbits presents new challenges since the libration point orbit period is on the order of two weeks rather than six months. As a result, stationkeeping maneuvers to maintain the Lissajous orbit will need to be performed frequently, and the orbit determination solutions between maneuvers will need to be quite accurate. The ARTEMIS mission is a collaborative effort between NASA GSFC, the University of California at Berkeley (UCB), and the Jet Propulsion Laboratory (JPL). The ARTEMIS mission is part of the THEMIS extended mission. ARTEMIS comprises two of the five THEMIS spacecraft that will be maneuvered from near-Earth orbits into lunar libration orbits using a sequence of designed orbital maneuvers and Moon & Earth gravity assists. In July 2009, a series of orbit-raising maneuvers began the proper orbit phasing of the two spacecraft for the first lunar flybys. Over subsequent months, additional propulsive maneuvers and gravity assists will be performed to move each spacecraft though the Sun-Earth weak stability regions and eventually into Earth-Moon libration point orbits. We will present the overall orbit designs for the two ARTEMIS spacecraft and provide analysis results of the 3/4-body dynamics, and the sensitivities of the trajectory design to both · maneuver errors and orbit determination errors. We will present results from the. initial orbit-raising maneuvers.

  19. Aiming at a 1-cm orbit for low earth orbiters : Reduced-dynamic and kinematic precise orbit determination

    NARCIS (Netherlands)

    Visser, P.N.A.M.; Van den IJssel, J.


    The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP, GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at the few cm level. Such a level of accuracy might be

  20. Orbit Propagation and Determination of Low Earth Orbit Satellites

    Directory of Open Access Journals (Sweden)

    Ho-Nien Shou


    Full Text Available This paper represents orbit propagation and determination of low Earth orbit (LEO satellites. Satellite global positioning system (GPS configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP. The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan to use a nonlinear filtering method for immediate orbit tasks requires more precise satellite orbit state parameters in a short time. Although the traditional extended Kalman filter (EKF method is widely used, its linear approximation of the drawbacks in dealing with nonlinear problems was especially evident, without compromising Kalman filter (unscented Kalman Filter, UKF. As a new nonlinear estimation method, it is measured at the estimated measurements on more and more applications. This paper will be the first study on UKF microsatellites in LEO orbit in real time, trying to explore the real-time precision orbit determination techniques. Through the preliminary simulation results, they show that, based on orbit mission requirements and conditions using UKF, they can satisfy the positioning accuracy and compute two indicators.

  1. Sampling analysis for the Earth Radiation Budget Satellite System mission based on orbital coverage and cloud variability (United States)

    Harrison, E. F.; Gibson, G. G.; Minnis, P.


    The reported study represents an extension of an investigation by Harrison et al. (1976). Based on the results of sampling studies, two 98 deg inclined orbits coupled with a 56 deg inclination orbit appear to satisfy the science requirements on both regional and zonal scales. The NOAA sun-synchronous satellites in the TIROS-N series could adequately cover the high latitudes and a satellite having an inclination of 56 deg could provide sampling in the mid and low latitude areas where variations in radiation energetics are most dynamic. Attention is given to studies of time and space coverage, zonal evaluations, a regional analysis, and statistics describing the regional variations of cloud cover. A table is presented with data concerning the uncertainty of monthly mean reflected irradiance due to cloud variability for selected northern hemisphere regions.

  2. Mission design of a Pioneer Jupiter Orbiter (United States)

    Friedman, L. D.; Nunamaker, R. R.


    The Mission analysis and design work performed in order to define a Pioneer mission to orbit Jupiter is described. This work arose from the interaction with a science advisory 'Mission Definition' team and led to the present mission concept. Building on the previous Jupiter Orbiter-Satellite Tour development at JPL a magnetospheric survey mission concept is developed. The geometric control of orbits which then provide extensive local time coverage of the Jovian system is analyzed and merged with the various science and program objectives. The result is a 'flower-orbit' mission design, yielding three large apoapse excursions at various local times and many interior orbits whose shape and orientation is under continual modification. This orbit design, together with a first orbit defined by delivery of an atmospheric probe, yields a mission of high scientific interest.

  3. Extravehicular activity at geosynchronous earth orbit (United States)

    Shields, Nicholas, Jr.; Schulze, Arthur E.; Carr, Gerald P.; Pogue, William


    The basic contract to define the system requirements to support the Advanced Extravehicular Activity (EVA) has three phases: EVA in geosynchronous Earth orbit; EVA in lunar base operations; and EVA in manned Mars surface exploration. The three key areas to be addressed in each phase are: environmental/biomedical requirements; crew and mission requirements; and hardware requirements. The structure of the technical tasks closely follows the structure of the Advanced EVA studies for the Space Station completed in 1986.

  4. Investigation of Malaysian Low Earth Orbits for Remote Sensing Applications (United States)

    Okasha, M.; Shuib, I.; Idres, M.


    This paper explores the orbit design procedures of a low Earth satellite orbit for remote sensing mission. The mission objective is to gather images over Malaysia as an area of interest for a variety of applications such as land monitoring and digital mapping. The design procedures are mainly driven by the payload performance, lighting conditions and the coverage requirements. Standard CubeSat platform with a NanoCam is considered for the mission. Numerical investigations show the trade studies of various satellite orbital parameters and their impact on the performance. The orbital parameters are optimized to meet the mission design requirements.

  5. BioSentinel: Mission Development of a Radiation Biosensor to Gauge DNA Damage and Repair Beyond Low Earth Orbit on a 6U Nanosatellite. (United States)

    Lewis, Brian; Hanel, Robert; Bhattacharya, Sharmila; Ricco, Antonion J.; Agasid, Elwood; Reiss-Bubenheim, Debra; Straume, Tore; Parra, Macerena; Boone, Travis; Santa Maria, Sergio; hide


    We are designing and developing a "6U" (10 x 22 x 34 cm; 14 kg) nanosatellite as a secondary payload to fly aboard NASA's Space Launch System (SLS) Exploration Mission (EM) 1, scheduled for launch in late 2017. For the first time in over forty years, direct experimental data from biological studies beyond low Earth orbit (LEO) will be obtained during BioSentinel's 12- to 18- month mission. BioSentinel will measure the damage and repair of DNA in a biological organism and allow us to compare that to information from onboard physical radiation sensors. In order to understand the relative contributions of the space environment's two dominant biological perturbations, reduced gravity and ionizing radiation, results from deep space will be directly compared to data obtained in LEO (on ISS) and on Earth. These data points will be available for validation of existing biological radiation damage and repair models, and for extrapolation to humans, to assist in mitigating risks during future long-term exploration missions beyond LEO. The BioSentinel Payload occupies 4U of the spacecraft and will utilize the monocellular eukaryotic organism Saccharomyces cerevisiae (yeast) to report DNA double-strand-break (DSB) events that result from ambient space radiation. DSB repair exhibits striking conservation of repair proteins from yeast to humans. Yeast was selected because of 1) its similarity to cells in higher organisms, 2) the well-established history of strains engineered to measure DSB repair, 3) its spaceflight heritage, and 4) the wealth of available ground and flight reference data. The S. cerevisiae flight strain will include engineered genetic defects to prevent growth and division until a radiation-induced DSB activates the yeast's DNA repair mechanisms. The triggered culture growth and metabolic activity directly indicate a DSB and its successful repair. The yeast will be carried in the dry state within the 1-atm P/L container in 18 separate fluidics cards with each

  6. Fuel Optimization for Low Earth Orbit Maintenance

    Directory of Open Access Journals (Sweden)

    Yong Jae Park


    Full Text Available The resolution of Earth images taken from a satellite has close relation with satellite's altitude. If a satellite has lower altitude, it gets a picture having better resolution. However the satellite will be exposed to heavier air drag and will spend more fuel to maintain its altitude for a desired mission. Therefore, in this study, the required fuel to maintain very low earth orbit(LEO with severe air drag is analyzed using optimization method such as collocation method. The required fuel to maintain the low altitude has significantly increased as the mission altitude is lowered and the solar activity is maximized. This study also shows that the fuel reduced by increasing the period of the satellite maneuver is very small, and that slightly increasing the satellite's mission altitude is much effective in reducing the amount of fuel to maintain its altitude. The calculated fuel to maintain very low earth orbit in this study would give useful information in planning the budget of fuel and cost for LEO satellites.

  7. Earth to Orbit Beamed Energy Experiment (United States)

    Johnson, Les; Montgomery, Edward E.


    As a means of primary propulsion, beamed energy propulsion offers the benefit of offloading much of the propulsion system mass from the vehicle, increasing its potential performance and freeing it from the constraints of the rocket equation. For interstellar missions, beamed energy propulsion is arguably the most viable in the near- to mid-term. A near-term demonstration showing the feasibility of beamed energy propulsion is necessary and, fortunately, feasible using existing technologies. Key enabling technologies are large area, low mass spacecraft and efficient and safe high power laser systems capable of long distance propagation. NASA is currently developing the spacecraft technology through the Near Earth Asteroid Scout solar sail mission and has signed agreements with the Planetary Society to study the feasibility of precursor laser propulsion experiments using their LightSail-2 solar sail spacecraft. The capabilities of Space Situational Awareness assets and the advanced analytical tools available for fine resolution orbit determination now make it possible to investigate the practicalities of an Earth-to-orbit Beamed Energy eXperiment (EBEX) - a demonstration at delivered power levels that only illuminate a spacecraft without causing damage to it. The degree to which this can be expected to produce a measurable change in the orbit of a low ballistic coefficient spacecraft is investigated. Key system characteristics and estimated performance are derived for a near term mission opportunity involving the LightSail-2 spacecraft and laser power levels modest in comparison to those proposed previously. While the technology demonstrated by such an experiment is not sufficient to enable an interstellar precursor mission, if approved, then it would be the next step toward that goal.

  8. Aristoteles - An ESA mission to study the earth's gravity field (United States)

    Lambeck, K.

    In preparing for its first Solid-Earth Program, ESA has studied a satellite concept for a mission dedicated to the precise determination of the earth's geopotential (gravitational and magnetic) fields. Data from such a mission are expected to make substantial contributions to a number of research and applications fields in solid-earth geophysics, oceanography and global-change monitoring. The impact of a high-resolution gravity-field mission on studies of the various earth-science problems is assessed. The current state of our knowledge in this area is discussed and the ability of low-orbit satellite gradiometry to contribute to their solution is demonstrated.

  9. The earth orbiting space debris

    Directory of Open Access Journals (Sweden)

    Rossi A.


    Full Text Available The space debris population is similar to the asteroid belt, since it is subject to a process of high-velocity mutual collisions that affects the long-term evolution of its size distribution. Presently, more than 10 000 artificial debris particles with diameters larger than 10 cm (and more than 300 000 with diameters larger than 1 cm are orbiting the Earth, and are monitored and studied by a large network of sensors around the Earth. Many objects of different kind compose the space debris population, produced by different source mechanisms ranging from high energy fragmentation of large spacecraft to slow diffusion of liquid metal. The impact against a space debris is a serious risk that every spacecraft must face now and it can be evaluated with ad-hoc algorithms. The long term evolution of the whole debris population is studied with computer models allowing the simulation of all the known source and sink mechanisms. One of these codes is described in this paper and the evolution of the debris environment over the next 100 years, under different traffic scenarios, is shown, pointing out the possible measures to mitigate the growth of the orbital debris population. .

  10. Libration Orbit Mission Design: Applications of Numerical & Dynamical Methods (United States)

    Bauer, Frank (Technical Monitor); Folta, David; Beckman, Mark


    Sun-Earth libration point orbits serve as excellent locations for scientific investigations. These orbits are often selected to minimize environmental disturbances and maximize observing efficiency. Trajectory design in support of libration orbits is ever more challenging as more complex missions are envisioned in the next decade. Trajectory design software must be further enabled to incorporate better understanding of the libration orbit solution space and thus improve the efficiency and expand the capabilities of current approaches. The Goddard Space Flight Center (GSFC) is currently supporting multiple libration missions. This end-to-end support consists of mission operations, trajectory design, and control. It also includes algorithm and software development. The recently launched Microwave Anisotropy Probe (MAP) and upcoming James Webb Space Telescope (JWST) and Constellation-X missions are examples of the use of improved numerical methods for attaining constrained orbital parameters and controlling their dynamical evolution at the collinear libration points. This paper presents a history of libration point missions, a brief description of the numerical and dynamical design techniques including software used, and a sample of future GSFC mission designs.

  11. Taurus Lightweight Manned Spacecraft Earth orbiting vehicle (United States)

    Bosset, M.

    The Taurus Lightweight Manned Spacecraft (LMS) was developed by students of the University of Maryland's Aerospace Engineering course in Space Vehicle Design. That course required students to design an Alternative Manned Spacecraft (AMS) to augment or replace the Space Transportation System and meet the following design requirements: (1) launch on the Taurus Booster being developed by Orbital Sciences Corporation; (2) 99.9 percent assured crew survival rate; (3) technology cutoff date of 1 Jan. 1991; (4) compatibility with current space administration infrastructure; and (5) first flight by May 1995. The Taurus LMS design meets the above requirements and represents an initial step toward larger and more complex spacecraft. The Taurus LMS has a very limited application when compared to the space shuttle, but it demonstrates that the U.S. can have a safe, reliable, and low-cost space system. The Taurus LMS is a short mission duration spacecraft designed to place one man into low Earth orbit (LEO). The driving factor for this design was the low payload carrying capabilities of the Taurus Booster - 1300 kg to a 300-km orbit. The Taurus LMS design is divided into six major design sections. The Human Factors section deals with the problems of life support and spacecraft cooling. The Propulsion section contains the Abort System, the Orbital Maneuvering System (OMS), the Reaction Control System (RCS), and Power Generation. The thermal protection systems and spacecraft structure are contained in the Structures section. The Avionics section includes Navigation, Attitude Determination, Data Processing, Communication systems, and Sensors. The Mission Analysis section was responsible for ground processing and spacecraft astrodynamics. The Systems Integration Section pulled the above sections together into one spacecraft, and addressed costing and reliability.

  12. Early Mission Maneuver Operations for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission (United States)

    Roberts, Craig; Case, Sara; Reagoso, John; Webster, Cassandra


    The Deep Space Climate Observatory mission launched on February 11, 2015, and inserted onto a transfer trajectory toward a Lissajous orbit around the Sun-Earth L1 libration point. This paper presents an overview of the baseline transfer orbit and early mission maneuver operations leading up to the start of nominal science orbit operations. In particular, the analysis and performance of the spacecraft insertion, mid-course correction maneuvers, and the deep-space Lissajous orbit insertion maneuvers are discussed, com-paring the baseline orbit with actual mission results and highlighting mission and operations constraints..

  13. SWARM - An earth Observation Mission investigating Geospace

    DEFF Research Database (Denmark)

    Friis-Christensen, Eigil; Lühr, H.; Knudsen, D.


    The Swarm mission was selected as the 5th mission in ESA's Earth Explorer Programme in 2004. This mission aims at measuring the Earth's magnetic field with unprecedented accuracy. This will be done by a constellation of three satellites, where two will fly at lower altitude, measuring the gradient...... of the Swarm science objectives, the mission concept, the scientific instrumentation, and the expected contribution to the ILWS programme will be summarized. (C) 2007 Published by Elsevier Ltd on behalf of COSPAR....

  14. Study on Earth Radiation Budget mission scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Dlhopolsky, R.; Hollmann, R.; Mueller, J.; Stuhlmann, R. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik


    The goal of this study is to study optimized satellite configurations for observation of the radiation balance of the earth. We present a literature survey of earth radiation budget missions and instruments. We develop a parametric tool to simulate realistic multiple satellite mission scenarios. This tool is a modular computer program which models satellite orbits and scanning operation. We use Meteosat data sampled at three hour intervals as a database to simulate atmospheric scenes. Input variables are satellite equatorial crossing time and instrument characteristics. Regional, zonal and global monthly averages of shortwave and longwave fluxes for an ideal observing system and several realistic satellite scenarios are produced. Comparisons show that the three satellite combinations which have equatorial crossing times at midmorning, noon and midafternoon provide the best shortwave monitoring. Crossing times near sunrise and sunset should be avoided for the shortwave. Longwave diurnal models are necessary over and surfaces and cloudy regions, if there are only two measurements made during daylight hours. We have found in the shortwave inversion comparison that at least 15% of the monthly regional errors can be attributed to the shortwave anisotropic models used. (orig.) 68 refs.

  15. Overview of a Preliminary Destination Mission Concept for a Human Orbital Mission to the Martial Moons (United States)

    Mazanek, D. D.; Abell, P. A.; Antol, J.; Barbee, B. W.; Beaty, D. W.; Bass, D. S.; Castillo-Rogez, J. C.; Coan, D. A.; Colaprete, A.; Daugherty, K. J.; hide


    The National Aeronautics and Space Administration s Human Spaceflight Architecture Team (HAT) has been developing a preliminary Destination Mission Concept (DMC) to assess how a human orbital mission to one or both of the Martian moons, Phobos and Deimos, might be conducted as a follow-on to a human mission to a near-Earth asteroid (NEA) and as a possible preliminary step prior to a human landing on Mars. The HAT Mars-Phobos-Deimos (MPD) mission also permits the teleoperation of robotic systems by the crew while in the Mars system. The DMC development activity provides an initial effort to identify the science and exploration objectives and investigate the capabilities and operations concepts required for a human orbital mission to the Mars system. In addition, the MPD Team identified potential synergistic opportunities via prior exploration of other destinations currently under consideration.

  16. Earth-Mars transfers through Moon Distant Retrograde Orbits (United States)

    Conte, Davide; Di Carlo, Marilena; Ho, Koki; Spencer, David B.; Vasile, Massimiliano


    This paper focuses on the trajectory design which is relevant for missions that would exploit the use of asteroid mining in stable cis-lunar orbits to facilitate deep space missions, specifically human Mars exploration. Assuming that a refueling "gas station" is present at a given lunar Distant Retrograde Orbit (DRO), ways of departing from the Earth to Mars via that DRO are analyzed. Thus, the analysis and results presented in this paper add a new cis-lunar departure orbit for Earth-Mars missions. Porkchop plots depicting the required C3 at launch, v∞ at arrival, Time of Flight (TOF), and total Δ V for various DRO departure and Mars arrival dates are created and compared with results obtained for low Δ V Low Earth Orbit (LEO) to Mars trajectories. The results show that propellant-optimal trajectories from LEO to Mars through a DRO have higher overall mission Δ V due to the additional stop at the DRO. However, they have lower Initial Mass in LEO (IMLEO) and thus lower gear ratio as well as lower TOF than direct LEO to Mars transfers. This results in a lower overall spacecraft dry mass that needs to be launched into space from Earth's surface.

  17. Cycler orbit between Earth and Mars (United States)

    Byrnes, Dennis V.; Longuski, James M.; Aldrin, Buzz


    A periodic orbit between Earth and Mars has been discovered that, after launch, permits a space vehicle to cycle back and forth between the planets with moderate maneuvers at irregular intervals. A Space Station placed in this cycler orbit could provide a safe haven from radiation and comfortable living quarters for astronauts en route to Earth or Mars. The orbit is largely maintained by gravity assist from Earth. Numerical results from multiconic optimization software are presented for a 15-year period from 1995 through 2010.

  18. Near-Earth Object Survey Orbit Quality Analysis (United States)

    Buie, Marc W.


    Abstract (2,250 Maximum Characters): The Sentinel Mission is currently under development by the B612 Foundation and Ball Aerospace. The mission concept is based on a space-based infrared telescope in an independent orbit similar to that of Venus. Being in an orbit interior to the Earth greatly reduces the time to complete the survey of the near-Earth region compared to a similar survey that could be accomplished from ground-based or orbiting observatory near the Earth. One of the key mission design elements is the cadence of observation. This involves the tiling pattern for how the instrument field-of-view maps out the sky and the repeat interval between successive observations. This presentation will show a quantitative analysis of orbit determination from this type of platform and show how the expected distribution of NEOs will be observed and the orbit qualities that will result. From this analysis, limits can then be placed on the degree of confusion that the cadence can tolerate before linking different epochs becomes problematic.

  19. Stability and Evolution of Orbits around Binary Asteroids: Applications to the Marco Polo Mission Scenario (United States)

    Wickhusen, K.; Oberst, J.; Hussmann, H.; Shi, X.; Damme, F.


    We have analyzed the orbit stability of a spacecraft moving around a small Near-Earth-Asteroid (NEA), focusing on the primary target of the Marco Polo Mission: 175706 (1996 FG3). The simulation showed that most orbits are unstable over time but under certain conditions the S/C stays in orbit without crashing or escaping into space.

  20. SEP Mission Design Space for Mars Orbiters (United States)

    Woolley, Ryan C.; Nicholas, Austin K.


    The advancement of solar-electric propulsion (SEP) technologies and larger, light-weight solar arrays offer a tremendous advantage to Mars orbiters in terms of both mass and timeline flexibility. These advantages are multiplied for round-trip orbiters (e.g. potential Mars sample return) where a large total Delta V would be required. In this paper we investigate the mission design characteristics of mission concepts utilizing various combinations and types of SEP thrusters, solar arrays, launch vehicles, launch dates, arrival dates, etc. SEP allows for greater than 50% more mass delivered and launch windows of months to years. We also present the SEP analog to the ballistic Porkchop plot - the "Bacon" plot.

  1. Evaluation of flat-Earth approximation results for geopotential missions. (United States)

    Tapley, M. B.


    Simplified calculations can approximate the formal uncertainties in estimates of the spherical harmonic coefficients representing the Earth's gravitational potential. The calculations model the Earth locally as a plane, producing errors negligible for wavelengths shorter than the radius of the Earth. Information derived from observations of low altitude polar orbiting satellites is considered. With some constraints, the final model uncertainties derive from a priori gravitational field information, specific orbital elements, and parameters describing instrumentation characteristics. The author demonstrates how to refine the technique to accept inputs from the currently operational Navstar Global Positioning System (GPS) constellation and how to use information from partial tensor gravitational gradiometers. This approach is beneficial when evaluating prospective satellite geodesy missions because the covariance analyses for various mission scenarios can be made efficiently and expeditiously. The author demonstrates the utility of the flat Earth approach by comparing results with those of more elaborate and time consuming calculations performed for the European Space Agency ARISTOTELES proposed geopotential mapping mission, the NASA Gravity Probe B Relativity mission, and the NASA/Center National d'Etudes Spatiales Topographic Ocean Experiment Satellite (TOPEX)/Poseidon mission.

  2. Magnetospheric Multiscale (MMS) Mission Commissioning Phase Orbit Determination Error Analysis (United States)

    Chung, Lauren R.; Novak, Stefan; Long, Anne; Gramling, Cheryl


    The Magnetospheric MultiScale (MMS) mission commissioning phase starts in a 185 km altitude x 12 Earth radii (RE) injection orbit and lasts until the Phase 1 mission orbits and orientation to the Earth-Sun li ne are achieved. During a limited time period in the early part of co mmissioning, five maneuvers are performed to raise the perigee radius to 1.2 R E, with a maneuver every other apogee. The current baseline is for the Goddard Space Flight Center Flight Dynamics Facility to p rovide MMS orbit determination support during the early commissioning phase using all available two-way range and Doppler tracking from bo th the Deep Space Network and Space Network. This paper summarizes th e results from a linear covariance analysis to determine the type and amount of tracking data required to accurately estimate the spacecraf t state, plan each perigee raising maneuver, and support thruster cal ibration during this phase. The primary focus of this study is the na vigation accuracy required to plan the first and the final perigee ra ising maneuvers. Absolute and relative position and velocity error hi stories are generated for all cases and summarized in terms of the ma ximum root-sum-square consider and measurement noise error contributi ons over the definitive and predictive arcs and at discrete times inc luding the maneuver planning and execution times. Details of the meth odology, orbital characteristics, maneuver timeline, error models, and error sensitivities are provided.

  3. The Mission Accessibility of Near-Earth Asteroids (United States)

    Barbee, Brent W.; Abell, Paul A.; Adamo, Daniel R.; Mazanek, Daniel D.; Johnson, Lindley N.; Yeomans, Donald K.; Chodas, Paul W.; Chamberlin, Alan B.; Benner, Lance A. M.; Taylor, Patrick; hide


    Astrodynamical Earth departure dates; mission v; mission duration; stay time; etc. Physical I NEO size(?); rotation rate; dust satellites environment; chemistry; etc. Architectural Launch vehicle(s); crew vehicle(s); habitat module(s); budget; etc. Operational Operations experience; abort options profiles; etc. Astrodynamical Accessibility is the starting point for understanding the options and opportunities available to us. Here we shall focus on. Astrodynamical Accessibility.2 Earth departure date between 2015-01-01 and 2040-12-31 Earth departure C3 60 km2s2. Total mission v 12 kms. The total v includes (1) the Earth departure maneuver from a 400 km altitude circular parking orbit, (2) the maneuver to match the NEAs velocity at arrival, (3) the maneuver to depart the NEA and, (4) if necessary, a maneuver to control the atmospheric re-entry speed during Earth return. Total round trip mission duration 450 days. Stay time at the NEA 8 days Earth atmospheric entry speed 12 kms at an altitude of 125 km. A near-Earth asteroid (NEA) that offers at least one trajectory solution meeting those criteria is classified as NHATS-compliant.

  4. Precise halo orbit design and optimal transfer to halo orbits from earth using differential evolution (United States)

    Nath, Pranav; Ramanan, R. V.


    The mission design to a halo orbit around the libration points from Earth involves two important steps. In the first step, we design a halo orbit for a specified size and in the second step, we obtain an optimal transfer trajectory design to the halo orbit from an Earth parking orbit. Conventionally, the preliminary design for these steps is obtained using higher order analytical solution and the dynamical systems theory respectively. Refinements of the design are carried out using gradient based methods such as differential correction and pseudo arc length continuation method under the of circular restricted three body model. In this paper, alternative single level schemes are developed for both of these steps based on differential evolution, an evolutionary optimization technique. The differential evolution based scheme for halo orbit design produces precise halo orbit design avoiding the refinement steps. Further, in this approach, prior knowledge of higher order analytical solutions for the halo orbit design is not needed. The differential evolution based scheme for the transfer trajectory, identifies the precise location on the halo orbit that needs minimum energy for insertion and avoids exploration of multiple points. The need of a close guess is removed because the present scheme operates on a set of bounds for the unknowns. The constraint on the closest approach altitude from Earth is handled through objective function. The use of these schemes as the design and analysis tools within the of circular restricted three body model is demonstrated through case studies for missions to the first libration point of Sun-Earth system.

  5. Mitigating Climate Change with Earth Orbital Sunshades (United States)

    Coverstone, Victoria; Johnson, Les


    An array of rotating sunshades based on emerging solar sail technology will be deployed in a novel Earth orbit to provide near-continuous partial shading of the Earth, reducing the heat input to the atmosphere by blocking a small percentage of the incoming sunlight, and mitigating local weather effects of anticipated climate change over the next century. The technology will provide local cooling relief during extreme heat events (and heating relief during extreme cold events) thereby saving human lives, agriculture, livestock, water and energy needs. A synthesis of the solar sail design, the sails' operational modes, and the selected orbit combine to provide local weather modification.

  6. Airbreathing Acceleration Toward Earth Orbit

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C


    As flight speed increases, aerodynamic drag rises more sharply than the availability of atmospheric oxygen. The ratio of oxygen mass flux to dynamic pressure cannot be improved by changing altitude. The maximum possible speed for airbreathing propulsion is limited by the ratio of air capture area to vehicle drag area, approximately Mach 6 at equal areas. Simulation of vehicle acceleration shows that the use of atmospheric oxygen offers a significant potential for minimizing onboard consumables at low speeds. These fundamental calculations indicate that a practical airbreathing launch vehicle would accelerate to near steady-state speed while consuming only onboard fuel, then transition to rocket propulsion. It is suggested that an aircraft carrying a rocket-propelled vehicle to approximately Mach 5 could be a realistic technical goal toward improving access to orbit.

  7. Gravity Recovery and Interior Laboratory Mission (GRAIL) Orbit Determination (United States)

    You, Tung-Han; Antreasian, Peter; Broschart, Stephen; Criddle, Kevin; Higa, Earl; Jefferson, David; Lau, Eunice; Mohan, Swati; Ryne, Mark; Keck, Mason


    Launched on 10 September 2011 from the Cape Canaveral Air Force Station, Florida, the twin-spacecraft Gravity Recovery and Interior Laboratory (GRAIL) has the primary mission objective of generating a lunar gravity map with an unprecedented resolution via the Ka-band Lunar Gravity Ranging System (LGRS). After successfully executing nearly 30 maneuvers on their six-month journey, Ebb and Flow (aka GRAIL-A and GRAIL-B) established the most stringent planetary formation orbit on 1 March 2012 of approximately 30 km x 90 km in orbit size. This paper describes the orbit determination (OD) filter configurations, analyses, and results during the Trans-Lunar Cruise, Orbit Period Reduction, and Transition to Science Formation phases. The maneuver reconstruction strategies and their performance will also be discussed, as well as the navigation requirements, major dynamic models, and navigation challenges. GRAIL is the first mission to generate a full high-resolution gravity field of the only natural satellite of the Earth. It not only enables scientists to understand the detailed structure of the Moon but also further extends their knowledge of the evolutionary histories of the rocky inner planets. Robust and successful navigation was the key to making this a reality.



    Sourgen, Frédéric; Prévereaud, Ysolde; Vérant, Jean-Luc; LAROCHE, Emmanuel; Moschetta, Jean-Marc


    The paper proposes an overview of the physical models developed/selected and implemented in the ONERA aerothermodynamic (ATD) engineering code FAST. This tool is used to quickly determine the pressure and heat flux surface distribution at the wall, as well as aerodynamic forces and moments coefficients in hypersonic regime for free-molecular, transitional and continuum flows, for realistic designs of space vehicles ranging from capsules to spacecrafts and for generic shapes of orbital debris ...

  9. Near-Earth Asteroid Retrieval Mission (ARM) Study (United States)

    Brophy, John R.; Muirhead, Brian


    The Asteroid Redirect Mission (ARM) concept brings together the capabilities of the science, technology, and the human exploration communities on a grand challenge combining robotic and human space exploration beyond low Earth orbit. This paper addresses the key aspects of this concept and the options studied to assess its technical feasibility. Included are evaluations of the expected number of potential targets, their expected discovery rate, the necessity to adequately characterize candidate mission targets, the process to capture a non-cooperative asteroid in deep space, and the power and propulsion technology required for transportation back to the Earth-Moon system. Viable options for spacecraft and mission designs are developed. Orbits for storing the retrieved asteroid that are stable for more than a hundred years, yet allow for human exploration and commercial utilization of a redirected asteroid, are identified. The study concludes that the key aspects of finding, capturing and redirecting an entire small, near-Earth asteroid to the Earth-Moon system by the first half of the next decade are technically feasible. The study was conducted from January 2013 through March 2013 by the Jet Propulsion Laboratory (JPL) in collaboration with Glenn Research Center (GRC), Johnson Space Center (JSC), Langley Research Center (LaRC), and Marshall Space Flight Center (MSFC).

  10. A comprehensive mission to planet Earth: Woods Hole Space Science and Applications Advisory Committee Planning Workshop (United States)


    The NASA program Mission to Planet Earth (MTPE) is described in this set of visuals presented in Massachusetts on July 29, 1991. The problem presented in this document is that the earth system is changing and that human activity accelerates the rate of change resulting in increased greenhouse gases, decreasing levels of stratospheric ozone, acid rain, deforestation, decreasing biodiversity, and overpopulation. Various national and international organizations are coordinating global change research. The complementary space observations for this activity are sun-synchronous polar orbits, low-inclination, low altitude orbits, geostationary orbits, and ground measurements. The Geostationary Earth Observatory is the major proposed mission of MTPE. Other proposed missions are EOS Synthetic Aperture Radar, ARISTOTELES Magnetic Field Experiment, and the Global Topography Mission. Use of the NASA DC-8 aircraft is outlined as carrying out the Airborne Science and Applications Program. Approved Earth Probes Program include the Total Ozone Mapping Spectrometer (TOMS). Other packages for earth observation are described.

  11. Going beyond: Target selection and mission analysis of human exploration missions to Near-Earth Asteroids (United States)

    Zimmer, A. K.; Messerschmid, E.


    Missions to Near-Earth Asteroids (NEAs) offer a wide range of possibilities for space exploration, scientific research, and technology demonstration. In particular, manned missions to NEAs provide a unique opportunity to be the first human expedition to an interplanetary body beyond the Earth-Moon system and represent the perfect environment to gain experience in deep-space operations, which is an indispensable prerequisite for human missions to Mars. As a starting point for the analysis of such missions, the objectives of this study are to identify target asteroids and evaluate possible transfer trajectories as well as the associated launch windows. The list of accessible asteroids is narrowed down by taking dynamical and structural properties such as size and rotation rate into account. An accessibility model for NEAs is developed allowing pre-selection of asteroid targets for human missions. For this model, a novel approach is taken which assesses the accessibility of a NEA not by considering its orbital parameters separately. Instead, accessibility is determined by evaluating the combination of all orbital parameters only limited by mission duration (less than 365 days) and round-trip Δv (less than 10 km/s). In order to verify the reliability of the model, mission architectures for missions departing from low-Earth orbit are investigated and transfers to 2567 NEAs in the time frame from 2020 to 2040 are simulated. Two hundred and forty asteroids are found to be accessible for human missions under the given boundary conditions and are observed to nicely fit the model developed. Seventy three of these remaining asteroids can be reached with a Δv≤7.5km/s, 15 of which allow mission durations of less than 200 days. One hundred and seventy launch windows strongly varying in duration are found for these 73 asteroids between 2020 and 2040. Launch opportunity analysis shows that several launch windows open every year in the given time frame for missions with

  12. Triple Difference Approach to Low Earth Orbiter Precision Orbit Determination (United States)

    Kwon, Jay-Hyoun; Grejner-Brzezinska, Dorota A.; Yom, Jae-Hong; Cheon, Lee-Dong


    A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position. P-KOD utilizes the precise GPS orbits and ground stations data from International GPS Service (IGS) so that the only unknown parameters to be solved are positions of the satellite at each epoch. Currently, the 3-D accuracy of P-KOD applied to CHAMP (CHAllenging Minisatellite Payload) shows better than 35 cm compared to the published rapid scientific orbit (RSO) solution from GFZ (GeoForschungsZentrum Potsdam). The data screening for cycle slips is a particularly challenging procedure for LEO, which moves very fast in the middle of the ionospheric layer. It was found that data screening using SNR (signal to noise ratio) generates best results based on the residual analysis using RSO. It is expected that much better accuracy are achievable with refined prescreening procedure and optimized geometry of the satellites and ground stations.

  13. The Orbiting Carbon Observatory: NASA's First Dedicated Carbon Dioxide Mission (United States)

    Crisp, D.


    The Orbiting Carbon Observatory is scheduled for launch from Vandenberg Air Force Base in California in January 2009. This Earth System Science Pathfinder (ESSP) mission carries and points a single instrument that incorporates 3 high-resolution grating spectrometers designed to measure the absorption of reflected sunlight by near-infrared carbon dioxide (CO2) and molecular oxygen bands. These spectra will be analyzed to retrieve estimates of the column-averaged CO2 dry air mole fraction, X(sub CO2). Pre-flight qualification and calibration tests completed in early 2008 indicate that the instrument will provide high quality X(sub CO2) data. The instrument was integrated into the spacecraft, and the completed Observatory was qualified and tested during the spring and summer of 2008, in preparation for delivery to the launch site in the fall of this year. The Observatory will initially be launched into a 635 km altitude, near-polar orbit. The on-board propulsion system will then raise the orbit to 705 km and insert OCO into the Earth Observing System Afternoon Constellation (A-Train). The first routine science observations are expected about 45 days after launch. Calibrated spectral radiances will be archived starting about 6 months later. An exploratory X(sub CO2) product will be validated and then archived starting about 3 months after that.

  14. Solid Earth ARISTOTELES mission data preprocessing simulation of gravity gradiometer (United States)

    Avanzi, G.; Stolfa, R.; Versini, B.

    Data preprocessing of the ARISTOTELES mission, which measures the Earth gravity gradient in a near polar orbit, was studied. The mission measures the gravity field at sea level through indirect measurements performed on the orbit, so that the evaluation steps consist in processing data from GRADIO accelerometer measurements. Due to the physical phenomena involved in the data collection experiment, it is possible to isolate at an initial stage a preprocessing of the gradiometer data based only on GRADIO measurements and not needing a detailed knowledge of the attitude and attitude rate sensors output. This preprocessing produces intermediate quantities used in future stages of the reduction. Software was designed and run to evaluate for this level of data reduction the achievable accuracy as a function of knowledge on instrument and satellite status parameters. The architecture of this element of preprocessing is described.

  15. Assessing the Impact of Earth Radiation Pressure Acceleration on Low-Earth Orbit Satellites (United States)

    Vielberg, Kristin; Forootan, Ehsan; Lück, Christina; Kusche, Jürgen; Börger, Klaus


    The orbits of satellites are influenced by several external forces. The main non-gravitational forces besides thermospheric drag, acting on the surface of satellites, are accelerations due to the Earth and Solar Radiation Pres- sure (SRP and ERP, respectively). The sun radiates visible and infrared light reaching the satellite directly, which causes the SRP. Earth also emits and reflects the sunlight back into space, where it acts on satellites. This is known as ERP acceleration. The influence of ERP increases with decreasing distance to the Earth, and for low-earth orbit (LEO) satellites ERP must be taken into account in orbit and gravity computations. Estimating acceler- ations requires knowledge about energy emitted from the Earth, which can be derived from satellite remote sensing data, and also by considering the shape and surface material of a satellite. In this sensitivity study, we assess ERP accelerations based on different input albedo and emission fields and their modelling for the satellite missions Challenging Mini-Satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE). As input fields, monthly 1°x1° products of Clouds and the Earth's Radiant En- ergy System (CERES), L3 are considered. Albedo and emission models are generated as latitude-dependent, as well as in terms of spherical harmonics. The impact of different albedo and emission models as well as the macro model and the altitude of satellites on ERP accelerations will be discussed.

  16. Return to Europa: Overview of the Jupiter Europa Orbiter Mission (United States)

    Clark, K.; Tan-Wang, G.; Boldt, J.; Greeley, R.; Jun, I.; Lock, R.; Ludwinski, J.; Pappalardo, R.; Van Houten, T.; Yan, T.


    Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, Galileo supplied fascinating new insights into that satellite's secrets. The Jupiter Europa Orbiter (JEO) would be the NASA-led portion of the Europa Jupiter System Mission (EJSM), an international mission with orbiters developed by NASA, ESA and possibly JAXA. JEO would address a very important subset of the complete EJSM science objectives and is designed to function alone or in conjunction with ESA's Jupiter Ganymede Orbiter (JGO).

  17. Orbit Determination of Spacecraft in Earth-Moon L1 and L2 Libration Point Orbits (United States)

    Woodard, Mark; Cosgrove, Daniel; Morinelli, Patrick; Marchese, Jeff; Owens, Brandon; Folta, David


    The ARTEMIS mission, part of the THEMIS extended mission, is the first to fly spacecraft in the Earth-Moon Lissajous regions. In 2009, two of the five THEMIS spacecraft were redeployed from Earth-centered orbits to arrive in Earth-Moon Lissajous orbits in late 2010. Starting in August 2010, the ARTEMIS P1 spacecraft executed numerous stationkeeping maneuvers, initially maintaining a lunar L2 Lissajous orbit before transitioning into a lunar L1 orbit. The ARTEMIS P2 spacecraft entered a L1 Lissajous orbit in October 2010. In April 2011, both ARTEMIS spacecraft will suspend Lissajous stationkeeping and will be maneuvered into lunar orbits. The success of the ARTEMIS mission has allowed the science team to gather unprecedented magnetospheric measurements in the lunar Lissajous regions. In order to effectively perform lunar Lissajous stationkeeping maneuvers, the ARTEMIS operations team has provided orbit determination solutions with typical accuracies on the order of 0.1 km in position and 0.1 cm/s in velocity. The ARTEMIS team utilizes the Goddard Trajectory Determination System (GTDS), using a batch least squares method, to process range and Doppler tracking measurements from the NASA Deep Space Network (DSN), Berkeley Ground Station (BGS), Merritt Island (MILA) station, and United Space Network (USN). The team has also investigated processing of the same tracking data measurements using the Orbit Determination Tool Kit (ODTK) software, which uses an extended Kalman filter and recursive smoother to estimate the orbit. The orbit determination results from each of these methods will be presented and we will discuss the advantages and disadvantages associated with using each method in the lunar Lissajous regions. Orbit determination accuracy is dependent on both the quality and quantity of tracking measurements, fidelity of the orbit force models, and the estimation techniques used. Prior to Lissajous operations, the team determined the appropriate quantity of tracking

  18. A polar orbit for the Mars Global Network Mission (United States)

    Knocke, Philip


    The purpose of the Global Network Mission (GNM) is to deploy simple landers on the Martian surface in late 1998. The objective is to create a globally distributed network of ground stations which will collect environmental data, perhaps for as long as several years. The GNM presents unique mission design challenges, which are addressed by the following essay. The GNM mission concept calls for two carrier spacecraft, each equipped with a number of simple landers. Some of the landers may be deployed from approach, either to reduce carrier mass prior to orbit insertion, or to reach latitudes not available from the carrier orbit. The remaining landers are deployed from orbit. One configuration for the Global Network Mission was proposed in a report from the Exploration Precursors Task Team to the Office of Space Science and Applications. This formed the basis of a previous orbit design for the GNM. This mission scenario is used as a point of reference, but results from the current study are generally applicable to a wide range of GNM mission variants. The analysis concluded that a 1/5 sol, polar orbit with a periapse altitude of 275 km offers the best circumstances for orbital deployment of the Global Network Mission landers. It allows easy polar access at nominal entry angles, and global dispersal of landing sites at lighting angles suitable for descent imaging. The polar orbit allows the option of deploying all the landers from orbit. A wait interval of 160 days after arrival is required before deployment can commence.

  19. Efficiency in Carrying Cargo to Earth Orbits: Spaceports Repositioning

    Directory of Open Access Journals (Sweden)

    Jakub Hospodka


    Full Text Available Space flights are in these days not any more question of technology, but more question of costs. One way how to decrease cost of launch is change of home spaceport. Change of home spaceport for different rockets is a way to achieve more efficient launches to space. The reason is different acceleration achieved from Earth rotation. We added several mathematical calculations of missions to Low Earth Orbit and Geostationary Earth Orbit to show bonuses from Earth rotation and effect of atmospheric drag on specific rockets used these days. We discussed only already used space vessels. Namely Arianne 5, Delta 4 heavy, Proton-M, Zenit and Falcon9. For reaching GEO we discuss possibility of using Hohmman transfer, because none of aforementioned vessels is available for direct GEO entry. As possible place for launch we discussed spaceports Baikonur, Kennedy Space center, Guyana Space center and Sea Launch platform. We present results in form of additional acceleration for each spaceport, and we also project this additional acceleration in means payload increase. In conclusion we find important differences between vessel effectivity based on spaceport used for launch. Change of launch location may bring significant cost decrease for operators.

  20. Earth Parking Orbit and Translunar Injection (United States)

    Interbartolo, Michael


    The objectives of this slide presentation are to (1) Describe the general characteristics of the Earth Parking Orbit (EPO) and Translunar Injection (TLI) (2) List the general activities that occurred during EPO (4) State what went into verifying a working Saturn IVB S-IVB IU and a CSM GNC (5) Differentiate between a Free-Return Trajectory vs. a Hybrid Non-Free-Return Trajectory (6) Identify the crew monitoring task during the TLI Burn and (7) Identify the abort modes in the event of severe systems problems during the TLI timeframe

  1. EUROCKOT Launch Services for ESA Earth Observation, Science and Technology Missions (United States)

    Leclerc, J.; Viertel, Y.; Freeborn, P.


    Eurockot Launch Services GmbH has become an established provider of commercial launch services particularly for organisations operating or planning to operate small earth observation, science and technology satellites in Low Earth Orbits (LEO). Eurockot has already performed a number of launches of earth observation missions for Germany, ESA, USA, Japan and the Republic of Korea in the recent past and presently has a backlog of future launches for the European Space Agency (ESA) and Japan encompassing missions from both the Earth Explorer and Technology programmes. This abstract gives an insight into these missions and also briefly touches on the capability of the Rockot launch vehicle to perform earth escape mission launches with the use of an additional kick-stage attached to the spacecraft, thereby addressing technology and science missions planned by ESA.

  2. Integrated Vehicle and Trajectory Design of Small Spacecraft with Electric Propulsion for Earth and Interplanetary Missions (United States)

    Spangelo, Sara; Dalle, Derek; Longmier, Benjamin


    This paper investigates the feasibility of Earth-transfer and interplanetary mission architectures for miniaturized spacecraft using emerging small solar electric propulsion technologies. Emerging small SEP thrusters offer significant advantages relative to existing technologies and will enable U-class systems to perform trajectory maneuvers with significant Delta V requirements. The approach in this paper is unique because it integrates trajectory design with vehicle sizing and accounts for the system and operational constraints of small U-class missions. The modeling framework includes integrated propulsion, orbit, energy, and external environment dynamics and systems-level power, energy, mass, and volume constraints. The trajectory simulation environment models orbit boosts in Earth orbit and flyby and capture trajectories to interplanetary destinations. A family of small spacecraft mission architectures are studied, including altitude and inclination transfers in Earth orbit and trajectories that escape Earth orbit and travel to interplanetary destinations such as Mercury, Venus, and Mars. Results are presented visually to show the trade-offs between competing performance objectives such as maximizing available mass and volume for payloads and minimizing transfer time. The results demonstrate the feasibility of using small spacecraft to perform significant Earth and interplanetary orbit transfers in less than one year with reasonable U-class mass, power, volume, and mission durations.

  3. An Earth Orbiting Satellite Service and Repair Facility (United States)

    Berndt, Andrew; Cardoza, Mike; Chen, John; Daley, Gunter; Frizzell, Andy; Linton, Richard; Rast, Wayne


    A conceptual design was produced for the Geosynchronous Satellite Servicing Platform (GSSP), an orbital facility capable of repairing and servicing satellites in geosynchronous orbit. The GSSP is a man-tended platform, which consists of a habitation module, operations module, service bay and truss assembly. This design review includes an analysis of life support systems, thermal and power requirements, robotic and automated systems, control methods and navigation, and communications systems. The GSSP will utilize existing technology available at the time of construction, focusing mainly on modifying and integrating existing systems. The entire facility, along with two satellite retrieval vehicles (SRV), will be placed in geosynchronous orbit by the Advanced Launch System. The SRV will be used to ferry satellites to and from the GSSP. Technicians will be transferred from Earth to the GSSP and back in an Apollo-derived Crew Transfer Capsule (CTC). These missions will use advanced telerobotic equipment to inspect and service satellites. Four of these missions are tentatively scheduled per year. At this rate, the GSSP will service over 650 satelites during the projected 25 year lifespan.

  4. MARCO POLO: near earth object sample return mission (United States)

    Barucci, M. A.; Yoshikawa, M.; Michel, P.; Kawagushi, J.; Yano, H.; Brucato, J. R.; Franchi, I. A.; Dotto, E.; Fulchignoni, M.; Ulamec, S.


    MARCO POLO is a joint European-Japanese sample return mission to a Near-Earth Object. This Euro-Asian mission will go to a primitive Near-Earth Object (NEO), which we anticipate will contain primitive materials without any known meteorite analogue, scientifically characterize it at multiple scales, and bring samples back to Earth for detailed scientific investigation. Small bodies, as primitive leftover building blocks of the Solar System formation process, offer important clues to the chemical mixture from which the planets formed some 4.6 billion years ago. Current exobiological scenarios for the origin of Life invoke an exogenous delivery of organic matter to the early Earth: it has been proposed that primitive bodies could have brought these complex organic molecules capable of triggering the pre-biotic synthesis of biochemical compounds. Moreover, collisions of NEOs with the Earth pose a finite hazard to life. For all these reasons, the exploration of such objects is particularly interesting and urgent. The scientific objectives of MARCO POLO will therefore contribute to a better understanding of the origin and evolution of the Solar System, the Earth, and possibly Life itself. Moreover, MARCO POLO provides important information on the volatile-rich (e.g. water) nature of primitive NEOs, which may be particularly important for future space resource utilization as well as providing critical information for the security of Earth. MARCO POLO is a proposal offering several options, leading to great flexibility in the actual implementation. The baseline mission scenario is based on a launch with a Soyuz-type launcher and consists of a Mother Spacecraft (MSC) carrying a possible Lander named SIFNOS, small hoppers, sampling devices, a re-entry capsule and scientific payloads. The MSC leaves Earth orbit, cruises toward the target with ion engines, rendezvous with the target, conducts a global characterization of the target to select a sampling site, and delivers small

  5. Tropical sea surface temperatures and the earth's orbital eccentricity cycles

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.; Fernandes, A.A.; Mohan, R.

    cyclicities at ~100- and ~400-ka corresponding to the Earth's orbital eccentricity cycles. Results, therefore imply that the tropical Indian Ocean warm pool persisted during the Quaternary and the paleo-SSTs fluctuating at the orbital eccentricity frequencies...

  6. Earth view: A business guide to orbital remote sensing (United States)

    Bishop, Peter C.


    The following subject areas are covered: Earth view - a guide to orbital remote sensing; current orbital remote sensing systems (LANDSAT, SPOT image, MOS-1, Soviet remote sensing systems); remote sensing satellite; and remote sensing organizations.

  7. Ground Contact Analysis for Korea’s Fictitious Lunar Orbiter Mission

    Directory of Open Access Journals (Sweden)

    Young-Joo Song


    Full Text Available In this research, the ground contact opportunity for the fictitious low lunar orbiter is analyzed to prepare for a future Korean lunar orbiter mission. The ground contact opportunity is basically derived from geometrical relations between the typical ground stations at the Earth, the relative positions of the Earth and Moon, and finally, the lunar orbiter itself. Both the cut-off angle and the orbiter’s Line of Sight (LOS conditions (weather orbiter is located at near or far side of the Moon seen from the Earth are considered to determine the ground contact opportunities. Four KOMPSAT Ground Stations (KGSs are assumed to be Korea’s future Near Earth Networks (NENs to support lunar missions, and world-wide separated Deep Space Networks (DSNs are also included during the contact availability analysis. As a result, it is concluded that about 138 times of contact will be made between the orbiter and the Daejeon station during 27.3 days of prediction time span. If these contact times are converted into contact duration, the duration is found to be about 8.55 days, about 31.31% of 27.3 days. It is discovered that selected four KGSs cannot provide continuous tracking of the lunar orbiter, meaning that international collaboration is necessary to track Korea’s future lunar orbiter effectively. Possible combinations of world-wide separated DSNs are also suggested to compensate for the lack of contact availability with only four KGSs, as with primary and backup station concepts. The provided algorithm can be easily modified to support any type of orbit around the Moon, and therefore, the presented results could aid further progress in the design field of Korea’s lunar orbiter missions.

  8. Earth Observatory Satellite system definition study. Report no. 1: Orbit/launch vehicle tradeoff studies and recommendations (United States)


    A study was conducted to determine the recommended orbit for the Earth Observatory Satellite (EOS) Land Resources Mission. It was determined that a promising sun synchronous orbit is 366 nautical miles when using an instrument with a 100 nautical mile swath width. The orbit has a 17 day repeat cycle and a 14 nautical mile swath overlap. Payloads were developed for each mission, EOS A through F. For each mission, the lowest cost booster that was capable of lifting the payload to the EOS orbit was selected. The launch vehicles selected for the missions are identified on the basis of tradeoff studies and recommendations. The reliability aspects of the launch vehicles are analyzed.

  9. Distributed Space Missions for Earth System Monitoring

    CERN Document Server


    A key addition to Springer's Space Technology Library series, this edited volume features the work of dozens of authors and offers a wealth of perspectives on distributed Earth observation missions. In sum, it is an eloquent synthesis of the fullest possible range of current approaches to a fast-developing field characterized by growing membership of the 'space club' to include nations formerly regarded as part of the Third World. The volume's four discrete sections focus on the topic's various aspects, including the key theoretical and technical issues arising from the division of payloads onto different satellites. The first is devoted to analyzing distributed synthetic aperture radars, with bi- and multi-static radars receiving separate treatment. This is followed by a full discussion of relative dynamics, guidance, navigation and control. Here, the separate topics of design; establishment, maintenance and control; and measurements are developed with relative trajectory as a reference point, while the dis...

  10. Low Earth Orbit Satellite’s Orbit Propagation and Determination (United States)


    Institute of Technology Email: Abstract This paper represents orbit propagation and determination of Low Eearth Orbit(LEO...Arichandran, S. H. Tan, T. Bretschneider, High – Presicion Onboard Orbit Determination for Small Satellites - the GPS-Based XNS on X-SAT. 6th Symposium on

  11. NASA's Near Earth Asteroid Scout Mission (United States)

    Johnson, Les; McNutt, Leslie; Castillo-Rogez, Julie


    NASA is developing solar sail propulsion for a near-term Near Earth Asteroid (NEA) reconnaissance mission and laying the groundwork for their future use in deep space science and exploration missions. The NEA Scout mission, funded by NASA's Advanced Exploration Systems Program and managed by NASA MSFC, will use the sail as primary propulsion allowing it to survey and image one or more NEA's of interest for possible future human exploration. NEA Scout uses a 6U cubesat (to be provided by NASA's Jet Propulsion Laboratory), an 86 m2 solar sail and will weigh less than 14 kilograms. The solar sail for NEA Scout will be based on the technology developed and flown by the NASA NanoSail-D and The Planetary Society's Lightsail-A. Four 7 m stainless steel booms wrapped on two spools (two overlapping booms per spool) will be motor deployed and pull the sail from its stowed volume. The sail material is an aluminized polyimide approximately 3 microns thick. NEA Scout will launch on the Space Launch System (SLS) first mission in 2018 and deploy from the SLS after the Orion spacecraft is separated from the SLS upper stage. The NEA Scout spacecraft will stabilize its orientation after ejection using an onboard cold-gas thruster system. The same system provides the vehicle Delta-V sufficient for a lunar flyby. After its first encounter with the moon, the 86 m2 sail will deploy, and the sail characterization phase will begin. A mechanical Active Mass Translation (AMT) system, combined with the remaining ACS propellant, will be used for sail momentum management. Once the system is checked out, the spacecraft will perform a series of lunar flybys until it achieves optimum departure trajectory to the target asteroid. The spacecraft will then begin its two year-long cruise. About one month before the asteroid flyby, NEA Scout will pause to search for the target and start its approach phase using a combination of radio tracking and optical navigation. The solar sail will provide

  12. Infrared near-Earth-object survey modeling for observatories interior to the Earth's orbit (United States)

    Buie, M.


    The search for and dynamical characterization of the near-Earth population of objects (NEOs) has been a busy topic for surveys for many years. Most of the work thus far has been from ground-based optical surveys such as the Catalina Sky Survey and LINEAR. These surveys have essentially reached a complete inventory of objects down to 1 km diameter and have shown that the known objects do not pose any significant impact threat. Smaller objects are correspondingly smaller threats but there are more of them and fewer of them have so far been discovered. The next generation of surveys is looking to extend their reach down to much smaller sizes. From an impact risk perspective, those objects as small as 30--40 m are still of interest (similar in size to the Tunguska bolide). Smaller objects than this are largely of interest from a space resource or in-situ analysis efforts. A recent mission concept promoted by the B612 Foundation and Ball Aerospace calls for an infrared survey telescope in a Venus-like orbit, known as the Sentinel Mission. This wide-field facility has been designed to complete the inventory down to a 140 m diameter while also providing substantial constraints on the NEO population down to a Tunguska-sized object. I have been working to develop a suite of tools to provide survey modeling for this class of survey telescope. The purpose of the tool is to uncover hidden complexities that govern mission design and operation while also working to quantitatively understand the orbit quality provided on its catalog of objects without additional followup assets. The baseline mission design calls for a 6.5 year survey lifetime. This survey model is a statistically based tool for establishing completeness as a function of object size and survey duration. Effects modeled include the ability to adjust the field-of-regard (includes all pointing restrictions), field-of-view, focal plane array fill factor, and the observatory orbit. Consequences tracked include time

  13. Near Earth Asteroids- Prospection, Orbit Modification and Mining (United States)

    Grandl, W.; Bazso, A.


    The number of known Near Earth Asteroids (NEAs) has increased continuously during the last decades. Now we understand the role of asteroid impacts for the evolution of life on Earth. To ensure that mankind will survive in the long run, we have to face the "asteroid threat" seriously. On one hand we will have to develop methods of detection and deflection for Hazardous Asteroids, on the other hand we can use these methods to modify their orbits and exploit their resources. Rare-earth elements, rare metals like platinum group elements, etc. may be extracted more easily from NEAs than from terrestrial soil, without environmental pollution or political and social problems. In a first step NEAs, which are expected to contain resources like nickel-iron, platinum group metals or rare-earth elements, will be prospected by robotic probes. Then a number of asteroids with a minimum bulk density of 2 g/cm^3 and a diameter of 150 to 500 m will be selected for mining. Given the long duration of an individual mission time of 10-20 years, the authors propose a "pipeline" concept. While the observation of NEAs can be done in parallel, the precursor missions of the the next phase can be launched in short intervals, giving time for technical corrections and upgrades. In this way a continuous data flow is established and there are no idle times. For our purpose Potentially Hazardous Asteroids (PHAs) seem to be a favorable choice for the following reasons: They have frequent closeencounters to Earth, their minimum orbit intersection distance is less than 0.05 AU (Astronomic Units) and they have diameters exceeding 150 meters. The necessary velocity change (delta V) for a spaceship is below 12 km/s to reach the PHA. The authors propose to modify the orbits of the chosen PHAs by orbital maneuvers from solar orbits to stable Earth orbits beyond the Moon. To change the orbits of these celestial bodies it is necessary to develop advanced propulsion systems. They must be able to deliver high

  14. Precise orbit computation for the Geosat Exact Repeat Mission (United States)

    Haines, Bruce J.; Born, George H.; Rosborough, George W.; Marsh, James G.; Williamson, Ronald G.


    Results are reported from an extensive investigation of orbit-determination strategies for the Geosat Exact Repeat Mission (ERM). The goal is to establish optimum geodetic parameters and procedures for the computation of the most accurate Geosat orbits possible and to apply these procedures for routine computation during the ERM for the following purposes: (1) to enhance the value of the Geosat oceanographic investigations by providing the user community with improved ephemerides, (2) to develop orbit determination techniques for the upcoming altimetric mission Topex/Poseidon, and (3) to assess the radial orbit accuracy obtainable with recently developed gravity models. To this end, ephemerides for the entire first year of the ERM have been computed using the GEODYN II orbit program on the Cyber 205 supercomputer system at the NASA Goddard.

  15. On the Mitigation of Solar Index Variability for High Precision Orbit Determination in Low Earth Orbit (United States)


    causing increased difficulty in achieving and maintaining high precision orbit predictions for satellites operating in low Earth orbit . In particular, the...Geodetic satellites with high precision satellite laser ranging data are used as test cases for the Naval Research Laboratory’s Orbit Covariance Estimation...forces imparted upon a satellite . For satellites in Low Earth Orbit (LEO), atmospheric drag forces are typically the largest source of force modeling error

  16. IUS/TUG Orbital Operations and Mission Support Study. Volume 1; Executive Summary (United States)


    The space transportation system (STS) is discussed which will include a propulsive stage that is carried into low earth orbit by the space shuttle. Data were accumulated from the analyses of various stage concepts, operating modes, and projected missions (space tug systems studies, growth stage studies, engine studies, and critical area studies). The foundation formulated by these studies aided in establishing a tentative two-phase approach for the extension of the STS operating regime beyond the space shuttle including plane changes, higher orbits, geosynchronous orbits and beyond. The orbital operations study, was conducted to provide the generation and analysis of operational plans, requirement, and concepts for the utilization of these vehicles. Primary emphasis was placed on methods and techniques to provide a sound technical approach to operations at reduced cost for the STS mission period.

  17. Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5

    DEFF Research Database (Denmark)

    Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric


    Observatory (STEREO) missions, but these missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line are also not well-suited to measure Earth-directed CMEs....... The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented...

  18. Dynamics of Orbits near 3:1 Resonance in the Earth-Moon System (United States)

    Dichmann, Donald J.; Lebois, Ryan; Carrico, John P., Jr.


    The Interstellar Boundary Explorer (IBEX) spacecraft is currently in a highly elliptical orbit around Earth with a period near 3:1 resonance with the Moon. Its orbit is oriented so that apogee does not approach the Moon. Simulations show this orbit to be remarkably stable over the next twenty years. This article examines the dynamics of such orbits in the Circular Restricted 3-Body Problem (CR3BP). We look at three types of periodic orbits, each exhibiting a type of symmetry of the CR3BP. For each of the orbit types, we assess the local stability using Floquet analysis. Although not all of the periodic solutions are stable in the mathematical sense, any divergence is so slow as to produce practical stability over several decades. We use Poincare maps with twenty-year propagations to assess the nonlinear stability of the orbits, where the perturbation magnitudes are related to the orbit uncertainty for the IBEX mission. Finally we show that these orbits belong to a family of orbits connected in a bifurcation diagram that exhibits exchange of stability. The analysis of these families of period orbits provides a valuable starting point for a mission orbit trade study.

  19. Computer subroutines for estimation of human exposure to radiation in low Earth orbit (United States)

    Cucinotta, F. A.; Wilson, J. W.


    Computer subroutines to calculate human exposure to trapped radiations in low Earth orbit (LEO) on the basis of a simple approximation of the human geometry by spherical shell shields of varying thickness are presented and detailed. The subroutines calculate the dose to critical body organs and the fraction of exposure limit reached as a function of altitude of orbit, degree of inclination, shield thickness, and days in mission. Exposure rates are compared with current exposure limits.

  20. The Earth-Moon Transfer Trajectory Design and Analysis using Intermediate Loop Orbits (United States)

    Song, Young-Joo; Woo, Jin; Park, Sang-Young; Kyu-Hong Choi; Sim, Eun-Sup


    Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI (Trans Lunar Injection) maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.

  1. The Earth-Moon Transfer Trajectory Design and Analysis using Intermediate Loop Orbits

    Directory of Open Access Journals (Sweden)

    Young-Joo Song


    Full Text Available Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI (Trans Lunar Injection maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.

  2. A Small Spacecraft Swarm Deployment and Stationkeeping Strategy for Sun-Earth L1 Halo Orbits (United States)

    Renea Conn, Tracie; Bookbinder, Jay


    Spacecraft orbits about the Sun-Earth librarian point L1 have been of interest since the 1950s. An L1 halo orbit was first achieved with the International Sun-Earth Explorer-3 (ISEE-3) mission, and similar orbits around Sun-Earth L1 were achieved in the Solar and Heliospheric Observatory (SOHO), Advanced Composition Explorer (ACE), Genesis, and Deep Space Climate Observatory (DSCOVR) missions. With recent advancements in CubeSat technology, we envision that it will soon be feasible to deploy CubeSats at L1. As opposed to these prior missions where one large satellite orbited alone, a swarm of CubeSats at L1 would enable novel science data return, providing a topology for intersatellite measurements of heliophysics phenomena both spatially and temporally, at varying spatial scales.The purpose of this iPoster is to present a flight dynamics strategy for a swarm of numerous CubeSats orbiting Sun-Earth L1. The presented method is a coupled, two-part solution. First, we present a deployment strategy for the CubeSats that is optimized to produce prescribed, time-varying intersatellite baselines for the purposes of collecting magnetometer data as well as radiometric measurements from cross-links. Second, we employ a loose control strategy that was successfully applied to SOHO and ACE for minimized stationkeeping propellant expenditure. We emphasize that the presented solution is practical within the current state-of-the-art and heritage CubeSat technology, citing capabilities of CubeSat designs that will launch on the upcoming Exploration Mission 1 (EM-1) to lunar orbits and beyond. Within this iPoster, we present animations of the simulated deployment strategy and resulting spacecraft trajectories. Mission design parameters such as total Δv required for long-term station keeping and minimum/maximum/mean spacecraft separation distances are also presented.

  3. Performance Evaluation of Orbit Determination System during Initial Phase of INSAT-3 Mission (United States)

    Subramanian, B.; Vighnesam, N. V.

    satellite. The orbit of the satellite had to be determined continuously at each stage of the initial phase of the mission at a brisk pace and this study shows that the ODS provided consistent results to meet the stringent requirements of the mission operations. At each stage of the mission the orbit was determined using tracking data obtained over varying periods of time. The orbit solutions obtained from short arc OD's are compared with that obtained using the longest arc OD of each stage of the initial phase of the mission. The results of this study have been tabled in this paper. The performance of the ODS in calibrating the ARIANE-4 launch vehicle has been analyzed. A comparison of the orbit elements obtained from the mission operational ODS with the injection parameters provided by CNES, Centre Spatial Guyanais has been made in this paper which shows that the satellite was injected well within the 1 dispersions quoted by ARIANE-SPACE. A comparison has also been shown between the determined transfer orbit elements with pre-launch nominal orbit elements. For the initial phase of this mission ranging support was provided by Hassan earth station at India and INMARSAT network of stations at LakeCowichan (Canada), Fucino (Italy) and Beijing (China). The performance of the tracking systems employed by these stations has been studied. The quality of tracking data obtained from these stations has also been assessed.

  4. Orbit/launch vehicle tradeoff studies. Earth Observatory Satellite system definition study (EOS) (United States)


    An evaluation of the Earth Observatory Satellite (EOS) design, performance, and cost factors which affect the choices of an orbit and a launch vehicle is presented. Primary emphasis is given to low altitude (300 to 900 nautical miles) land resources management applications for which payload design factors are defined. The subjects considered are: (1) a mission model, (2) orbit analysis and characterization, (3) characteristics and capabilities of candidate conventional launch vehicles, and space shuttle support. Recommendations are submitted for the EOS-A mission, the Single Multispectral Scanner payload, the Single Multispectral Scanner plus Thematic Mapper payload, the Dual Multispectral Scanner payload, and the Dual Multispectral Scanner plus Thematic Mapper payload.

  5. Earth Observatory Satellite system definition study. Report 1: Orbit/launch vehicle trade-off studies and recommendations (United States)


    A summary of the constraints and requirements on the Earth Observatory Satellite (EOS-A) orbit and launch vehicle analysis is presented. The propulsion system (hydrazine) and the launch vehicle (Delta 2910) selected for EOS-A are examined. The rationale for the selection of the recommended orbital altitude of 418 nautical miles is explained. The original analysis was based on the EOS-A mission with the Thematic Mapper and the High Resolution Pointable Imager. The impact of the revised mission model is analyzed to show how the new mission model affects the previously defined propulsion system, launch vehicle, and orbit. A table is provided to show all aspects of the EOS multiple mission concepts. The subjects considered include the following: (1) mission orbit analysis, (2) spacecraft parametric performance analysis, (3) launch system performance analysis, and (4) orbits/launch vehicle selection.

  6. Orbital debris and near-Earth environmental management: A chronology (United States)

    Portree, David S. F.; Loftus, Joseph P., Jr.


    This chronology covers the 32-year history of orbital debris and near-Earth environmental concerns. It tracks near-Earth environmental hazard creation, research, observation, experimentation, management, mitigation, protection, and policy-making, with emphasis on the orbital debris problem. Included are the Project West Ford experiments; Soviet ASAT tests and U.S. Delta upper stage explosions; the Ariane V16 explosion, U.N. treaties pertinent to near-Earth environmental problems, the PARCS tests; space nuclear power issues, the SPS/orbital debris link; Space Shuttle and space station orbital debris issues; the Solwind ASAT test; milestones in theory and modeling the Cosmos 954, Salyut 7, and Skylab reentries; the orbital debris/meteoroid research link; detection system development; orbital debris shielding development; popular culture and orbital debris; Solar Max results; LDEF results; orbital debris issues peculiar to geosynchronous orbit, including reboost policies and the stable plane; seminal papers, reports, and studies; the increasing effects of space activities on astronomy; and growing international awareness of the near-Earth environment.

  7. Multi-spectral optical scanners for commercial earth observation missions (United States)

    Schröter, Karin; Engel, Wolfgang; Berndt, Klaus


    In recent years, a number of commercial Earth observation missions have been initiated with the aim to gather data in the visible and near-infrared wavelength range. Some of these missions aim at medium resolution (5 to 10 m) multi-spectral imaging with the special background of daily revisiting. Typical applications aim at monitoring of farming area for growth control and harvest prediction, irrigation control, or disaster monitoring such as hail damage in farming, or flood survey. In order to arrive at profitable business plans for such missions, it is mandatory to establish the space segment, i.e. the spacecraft with their opto -electronic payloads, at minimum cost while guaranteeing maximum reliability for mission success. As multiple spacecraft are required for daily revisiting, the solutions are typically based on micro-satellites. This paper presents designs for multi-spectral opto-electric scanners for this type of missions. These designs are drive n by minimum mass and power budgets of microsatellites, and the need for minimum cost. As a consequence, it is mandatory to arrive at thermally robust, compact telescope designs. The paper gives a comparison between refractive, catadioptric, and TMA optics. For mirror designs, aluminium and Zerodur mirror technologies are briefly discussed. State-of-the art focal plane designs are presented. The paper also addresses the choice of detector technologies such as CCDs and CMOS Active Pixel Sensors. The electronics of the multi-spectral scanners represent the main design driver regarding power consumption, reliability, and (most often) cost. It can be subdivided into the detector drive electronics, analog and digital data processing chains, the data mass memory unit, formatting and down - linking units, payload control electronics, and local power supply. The paper gives overviews and trade-offs between data compression strategies and electronics solutions, mass memory unit designs, and data formatting approaches

  8. Equilibrium Temperature of a Satellite in LowEarth Orbit

    Directory of Open Access Journals (Sweden)

    T. M. Hegab


    Full Text Available The efficiency of artificial satellite equipment, essentially, depends on its temperature condition, which in the case of low-Earth orbit varies quite widely. The satellite temperature changes because of the fact that along with a portion of the orbit where the satellite perceives heat flows, caused by solar radiation directly incident on its surface and solar radiation, reflected from the Earth's surface; in general cases of the low earth orbit there is its shaded portion where the satellite receives only a relatively low intensive self-radiation of the Earth. The level of possible values of satellite temperature at different portions of low earth orbit can be estimated by the equilibrium temperature determined from the balance equation of heat flows, perceived and radiated by its surface.The analysis of heat flows, which act on the surface of an artificial satellite of conditional spherical shape, allows us to obtain the dependences, in order to find a satellite equilibrium temperature at different heights of its position above Earth's surface and an angle between the directions from the center of the Earth towards the Sun, and the satellite as it moves out of the shadow of the Earth and at different height of its position at the shaded portion of the orbit as well. These dependencies are used for graphing to show the changes of the equilibrium temperature of the low-Earth orbiting satellite.The presented technique allows us to evaluate the possible range of temperature change of the low-Earth orbiting satellite.

  9. The Lunar IceCube Mission Challenge: Attaining Science Orbit Parameters from a Constrained Approach Trajectory (United States)

    Folta, David C.; Bosanac, Natasha; Cox, Andrew; Howell, Kathleen C.


    The challenges of targeting specific lunar science orbit parameters from a concomitant Sun-Earth/Moon system trajectory are examined. While the concept of ballistic lunar capture is well-studied, achieving and controlling the time evolution of the orbital elements to satisfy mission constraints is especially problematic when the spacecraft is equipped with a low-thrust propulsion system. Satisfying these requirements on the lunar approach and capture segments is critical to the success of the Lunar IceCube mission, a 6U CubeSat that will prospect for water in solid (ice), liquid, and vapor forms and other lunar volatiles from a low-periapsis, highly inclined elliptical lunar orbit.

  10. The Lunar IceCube Mission Challenge: Attaining Science Orbit Parameters from a Constrained Approach Trajectory (United States)

    Folta, David C.; Bosanac, Natasha; Cox, Andrew; Howell, Kathleen C.


    The challenges of targeting specific lunar science orbit parameters from a concomitant Sun-EarthMoon system trajectory are examined. While the concept of ballistic lunar capture is well-studied, achieving and controlling the time evolution of the orbital elements to satisfy mission constraints is especially problematic when the spacecraft is equipped with a low-thrust propulsion system. Satisfying these requirements on the lunar approach and capture segments is critical to the success of the Lunar IceCube mission, a 6U CubeSat that will prospect for water in solid (ice), liquid, and vapor forms and other lunar volatiles from a low-periapsis, highly inclined elliptical lunar orbit.

  11. The Rosetta mission orbiter science overview: the comet phase (United States)

    Taylor, M. G. G. T.; Altobelli, N.; Buratti, B. J.; Choukroun, M.


    The international Rosetta mission was launched in 2004 and consists of the orbiter spacecraft Rosetta and the lander Philae. The aim of the mission is to map the comet 67P/Churyumov-Gerasimenko by remote sensing, and to examine its environment in situ and its evolution in the inner Solar System. Rosetta was the first spacecraft to rendezvous with and orbit a comet, accompanying it as it passes through the inner Solar System, and to deploy a lander, Philae, and perform in situ science on the comet's surface. The primary goals of the mission were to: characterize the comet's nucleus; examine the chemical, mineralogical and isotopic composition of volatiles and refractories; examine the physical properties and interrelation of volatiles and refractories in a cometary nucleus; study the development of cometary activity and the processes in the surface layer of the nucleus and in the coma; detail the origin of comets, the relationship between cometary and interstellar material and the implications for the origin of the Solar System; and characterize asteroids 2867 Steins and 21 Lutetia. This paper presents a summary of mission operations and science, focusing on the Rosetta orbiter component of the mission during its comet phase, from early 2014 up to September 2016. This article is part of the themed issue 'Cometary science after Rosetta'.

  12. The Rosetta mission orbiter science overview: the comet phase. (United States)

    Taylor, M G G T; Altobelli, N; Buratti, B J; Choukroun, M


    The international Rosetta mission was launched in 2004 and consists of the orbiter spacecraft Rosetta and the lander Philae. The aim of the mission is to map the comet 67P/Churyumov-Gerasimenko by remote sensing, and to examine its environment in situ and its evolution in the inner Solar System. Rosetta was the first spacecraft to rendezvous with and orbit a comet, accompanying it as it passes through the inner Solar System, and to deploy a lander, Philae, and perform in situ science on the comet's surface. The primary goals of the mission were to: characterize the comet's nucleus; examine the chemical, mineralogical and isotopic composition of volatiles and refractories; examine the physical properties and interrelation of volatiles and refractories in a cometary nucleus; study the development of cometary activity and the processes in the surface layer of the nucleus and in the coma; detail the origin of comets, the relationship between cometary and interstellar material and the implications for the origin of the Solar System; and characterize asteroids 2867 Steins and 21 Lutetia. This paper presents a summary of mission operations and science, focusing on the Rosetta orbiter component of the mission during its comet phase, from early 2014 up to September 2016.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Authors.

  13. The Rosetta mission orbiter science overview: the comet phase (United States)

    Altobelli, N.; Buratti, B. J.; Choukroun, M.


    The international Rosetta mission was launched in 2004 and consists of the orbiter spacecraft Rosetta and the lander Philae. The aim of the mission is to map the comet 67P/Churyumov–Gerasimenko by remote sensing, and to examine its environment in situ and its evolution in the inner Solar System. Rosetta was the first spacecraft to rendezvous with and orbit a comet, accompanying it as it passes through the inner Solar System, and to deploy a lander, Philae, and perform in situ science on the comet's surface. The primary goals of the mission were to: characterize the comet's nucleus; examine the chemical, mineralogical and isotopic composition of volatiles and refractories; examine the physical properties and interrelation of volatiles and refractories in a cometary nucleus; study the development of cometary activity and the processes in the surface layer of the nucleus and in the coma; detail the origin of comets, the relationship between cometary and interstellar material and the implications for the origin of the Solar System; and characterize asteroids 2867 Steins and 21 Lutetia. This paper presents a summary of mission operations and science, focusing on the Rosetta orbiter component of the mission during its comet phase, from early 2014 up to September 2016. This article is part of the themed issue ‘Cometary science after Rosetta’. PMID:28554981

  14. Autonomous On-Board Optical Navigation Beyond Earth Orbit Project (United States)

    National Aeronautics and Space Administration — To date, navigation solutions are created by ground systems teams and then uploaded to vehicles operating beyond Earth orbit. However with the improvement of...

  15. Analysis of Orbital Lifetime Prediction Parameters in Preparation for Post-Mission Disposal

    Directory of Open Access Journals (Sweden)

    Ha–Yeon Choi


    Full Text Available Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK® Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK® Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.

  16. Return to Europa: Overview of the Jupiter Europa orbiter mission (United States)

    Clark, K.; Boldt, J.; Greeley, R.; Hand, K.; Jun, I.; Lock, R.; Pappalardo, R.; van Houten, T.; Yan, T.


    Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter's icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander.The Jupiter Europa Orbiter (JEO) would be the NASA-led portion of the EJSM; JEO would address a very important subset of the complete EJSM science objectives and is designed to function alone or in conjunction with ESA's Jupiter Ganymede Orbiter (JGO). The JEO mission concept uses a single orbiter flight system that would travel to Jupiter by means of a multiple-gravity-assist trajectory and then perform a multi-year study of Europa and the Jupiter system, including 30 months of Jupiter system science and a comprehensive Europa orbit phase of 9 months.The JEO mission would investigate various options for future surface landings. The JEO mission science objectives, as defined by the international EJSM Science Definition Team, include:Europa's ocean: Characterize the extent of the ocean and its relation to the deeper interior.Europa's ice shell: Characterize the ice shell and any subsurface water, including their heterogeneity, and the nature of surface-ice-ocean exchange.Europa's chemistry: Determine global surface compositions and chemistry, especially as related to habitability.Europa's geology: Understand the formation of surface features, including sites of recent or current activity, and identify and characterize candidate sites for future in situ

  17. Applications of low-earth-orbit power transmission

    Energy Technology Data Exchange (ETDEWEB)

    Arndt, G.D.; Kerwin, E.M.


    The use of low-earth-orbit transmission systems to transfer power between two co-orbiting satellites is investigated. A microwave system with a 20 m antenna and 30 m rectenna over a 5-10 km operating range could have possible applications for transmitting 100 kW of power. Antenna/rectenna trade-off sizings, taper analyses, orbital considerations, and possible uses are discussed.

  18. Automated and Adaptive Mission Planning for Orbital Express (United States)

    Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Daniel; Koblick, Darin


    The Orbital Express space mission was a Defense Advanced Research Projects Agency (DARPA) lead demonstration of on-orbit satellite servicing scenarios, autonomous rendezvous, fluid transfers of hydrazine propellant, and robotic arm transfers of Orbital Replacement Unit (ORU) components. Boeing's Autonomous Space Transport Robotic Operations (ASTRO) vehicle provided the servicing to the Ball Aerospace's Next Generation Serviceable Satellite (NextSat) client. For communication opportunities, operations used the high-bandwidth ground-based Air Force Satellite Control Network (AFSCN) along with the relatively low-bandwidth GEO-Synchronous space-borne Tracking and Data Relay Satellite System (TDRSS) network. Mission operations were conducted out of the RDT&E Support Complex (RSC) at the Kirtland Air Force Base in New Mexico. All mission objectives were met successfully: The first of several autonomous rendezvous was demonstrated on May 5, 2007; autonomous free-flyer capture was demonstrated on June 22, 2007; the fluid and ORU transfers throughout the mission were successful. Planning operations for the mission were conducted by a team of personnel including Flight Directors, who were responsible for verifying the steps and contacts within the procedures, the Rendezvous Planners who would compute the locations and visibilities of the spacecraft, the Scenario Resource Planners (SRPs), who were concerned with assignment of communications windows, monitoring of resources, and sending commands to the ASTRO spacecraft, and the Mission planners who would interface with the real-time operations environment, process planning products and coordinate activities with the SRP. The SRP position was staffed by JPL personnel who used the Automated Scheduling and Planning ENvironment (ASPEN) to model and enforce mission and satellite constraints. The lifecycle of a plan began three weeks outside its execution on-board. During the planning timeframe, many aspects could change the plan

  19. Phasing Delta-V for transfers from Sun-Earth halo orbits to the Moon (United States)

    Chen, Hongru; Kawakatsu, Yasuhiro; Hanada, Toshiya


    Inspired by successful extended missions such as the ISEE-3, an investigation for the extended mission that involves a lunar encounter following a Sun-Earth halo orbit mission is considered valuable. Most previous studies present the orbit-to-orbit transfers where the lunar phase is not considered. Intended for extended missions, the present work aims to solve for the minimum phasing ∆V for various initial lunar phases. Due to the solution multiplicity of the two-point boundary value problem, the general constrained optimization algorithm that does not identify multiple feasible solutions is shown to miss minima. A two-step differential corrector with a two-body Lambert solver is developed for identifying multiple solutions. The minimum ∆V associated with the short-way and long-way approaches can be recovered. It is acquired that the required ∆V to cover all initial lunar phases is around 45 m/s for the halo orbit with out-of-plane amplitude Az greater than 3.5×105 km, and 14 m/s for a small halo orbit with Az=1×105 km. In addition, the paper discusses the phasing planning based on the ∆V result and the shift of lunar phase with halo orbit revolution.

  20. Modeling Earth Albedo for Satellites in Earth Orbit

    DEFF Research Database (Denmark)

    Bhanderi, Dan; Bak, Thomas


    Many satellite are influences by the Earthøs albedo, though very few model schemes order to predict this phenomenon. Earth albedo is often treated as noise, or ignored completely. When applying solar cells in the attitude hardware, Earth albedo can cause the attitude estimate to deviate......, in which the Earth Probe Satellite has recorded reflectivity data daily since mid 1996. The mean of these data can be used to calculate the Earth albedo given the positions of the satellite and the Sun. Our results show that the albedo varies highly with the solar angle to the satellite's field of view......, and that the longitude of the satellite position is significant to the model output. The results also show that the calculated albedo is generally lower than it would be expected based only on the reflectivity data....

  1. Numerical orbit generators of artificial earth satellites (United States)

    Kugar, H. K.; Dasilva, W. C. C.


    A numerical orbit integrator containing updatings and improvements relative to the previous ones that are being utilized by the Departmento de Mecanica Espacial e Controle (DMC), of INPE, besides incorporating newer modellings resulting from the skill acquired along the time is presented. Flexibility and modularity were taken into account in order to allow future extensions and modifications. Characteristics of numerical accuracy, processing quickness, memory saving as well as utilization aspects were also considered. User's handbook, whole program listing and qualitative analysis of accuracy, processing time and orbit perturbation effects were included as well.

  2. End-of-life disposal of high elliptical orbit missions: The case of INTEGRAL (United States)

    Armellin, Roberto; San-Juan, Juan F.; Lara, Martin


    Nowadays there is international consensus that space activities must be managed to minimize debris generation and risk. The paper presents a method for the end-of-life (EoL) disposal of spacecraft in high elliptical orbits (HEO). The time evolution of HEO is strongly affected by Earth's oblateness and luni-solar perturbation, and this can cause in the long-term to extended interferences with low Earth orbit (LEO) protected region and uncontrolled Earth re-entry. An EoL disposal concept that exploits the effect of orbital perturbations to reduce the disposal cost is presented. The problem is formulated as a multiobjective optimization problem, which is solved with an evolutionary algorithm. To explore at the best the search space a semi-analytical orbit propagator, which allows the propagation of the orbit motion for 100 years in few seconds, is adopted. The EoL disposal of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission is used as a practical test-case to show the effectiveness of the proposed methodology.

  3. An Earth-mass planet orbiting α Centauri B. (United States)

    Dumusque, Xavier; Pepe, Francesco; Lovis, Christophe; Ségransan, Damien; Sahlmann, Johannes; Benz, Willy; Bouchy, François; Mayor, Michel; Queloz, Didier; Santos, Nuno; Udry, Stéphane


    Exoplanets down to the size of Earth have been found, but not in the habitable zone--that is, at a distance from the parent star at which water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for reasons such as tidal locking and strong stellar activity, they are unlikely to harbour water-carbon life as we know it. The detection of a habitable Earth-mass planet orbiting a star similar to our Sun is extremely difficult, because such a signal is overwhelmed by stellar perturbations. Here we report the detection of an Earth-mass planet orbiting our neighbour star α Centauri B, a member of the closest stellar system to the Sun. The planet has an orbital period of 3.236 days and is about 0.04 astronomical units from the star (one astronomical unit is the Earth-Sun distance).

  4. MARCO POLO: A Near Earth Object Sample Return Mission (United States)

    Barucci, M. A.; Yoshikawa, M.; Michel, P.; Kawaguchi, J.; Yano, H.; Brucato, J. R.; Franchi, I. A.; Dotto, E.; Fulchignoni, M.; Ulamec, S.; Boehnhardt, H.; Coradini, M.; Green, S. F.; Josset, J.-L.; Koschny, D.; Muinonen, M.; Oberst, J.; Marco Polo Scienc


    MARCO POLO is a joint European-Japanese sample return mission to a near-Earth object. In late 2007 this mission was selected by ESA, in the framework of COSMIC VISION 2015-2025, for an assessment scheduled to last until mid 2009.

  5. Optimising the science orbits for the Joint Europa Mission (JEM). (United States)

    Desprats, William; Balmino, Georges; Laurent-Varin, Julien; Russell, Ryan


    JEM (a proposed NASA-ESA Joint Europa Mission) will be assigned the following overarching goal: Understand Europa as a complex system responding to Jupiter system forcing, characterize the habitability of its potential biosphere, and search for life in its surface, sub-surface and exosphere. The JEM observation strategy to address these goals will include measurements on a high-latitude, low-latitude Europan orbit providing a continuous and global mapping of planetary fields (magnetic and gravity) and of the neutral and charged environment during a period of three months, which will itself follow a sequence of science operations in halo orbit around the L1 Lagrangian point of the Europa-Jupiter system which will also be used to relay the data from the JEM lander. We will present a detailed mission analysis study by which the two successive sequences of science orbits have been optimized to best cover the JEM scientific objectives while satisfactorily fulfilling the mission constraints related to the lander delivery and relay functions.

  6. The Lunar Space Tug: A sustainable bridge between low Earth orbits and the Cislunar Habitat (United States)

    Mammarella, M.; Paissoni, C. A.; Viola, N.; Denaro, A.; Gargioli, E.; Massobrio, F.


    The International Space Station is the first space human outpost and over the last 15 years, it has represented a peculiar environment where science, technology and human innovation converge together in a unique microgravity and space research laboratory. With the International Space Station entering the second part of its life and its operations running steadily at nominal pace, the global space community is starting planning how the human exploration could move further, beyond Low-Earth-Orbit. According to the Global Exploration Roadmap, the Moon represents the next feasible path-way for advances in human exploration towards the nal goal, Mars. Based on the experience of the ISS, one of the most widespread ideas is to develop a Cislunar Station in preparation of long duration missions in a deep space environment. Cislunar space is de ned as the area of deep space under the influence of Earth-Moon system, including a set of special orbits, e.g. Earth-Moon Libration points and Lunar Retrograde Orbit. This habitat represents a suitable environment for demonstrating and testing technologies and capabilities in deep space. In order to achieve this goal, there are several crucial systems and technologies, in particular related to transportation and launch systems. The Orion Multi-Purpose Crew Vehicle is a reusable transportation capsule designed to provide crew transportation in deep space missions, whereas NASA is developing the Space Launch System, the most powerful rocket ever built, which could provide the necessary heavy-lift launch capability to support the same kind of missions. These innovations would allow quite-fast transfers from Earth to the Cislunar Station and vice versa, both for manned and unmanned missions. However, taking into account the whole Concept of Operations for both the growth and sustainability of the Cislunar Space Station, the Lunar Space Tug can be considered as an additional, new and fundamental element for the mission architecture. The

  7. Orbital mechanics and astrodynamics techniques and tools for space missions

    CERN Document Server

    Hintz, Gerald R


    This textbook covers fundamental and advanced topics in orbital mechanics and astrodynamics to expose the student to the basic dynamics of space flight. The engineers and graduate students who read this class-tested text will be able to apply their knowledge to mission design and navigation of space missions. Through highlighting basic, analytic and computer-based methods for designing interplanetary and orbital trajectories, this text provides excellent insight into astronautical techniques and tools. This book is ideal for graduate students in Astronautical or Aerospace Engineering and related fields of study, researchers in space industrial and governmental research and development facilities, as well as researchers in astronautics. This book also: ·       Illustrates all key concepts with examples ·       Includes exercises for each chapter ·       Explains concepts and engineering tools a student or experienced engineer can apply to mission design and navigation of space missions ·�...

  8. Regional positioning using a low Earth orbit satellite constellation (United States)

    Shtark, Tomer; Gurfil, Pini


    Global and regional satellite navigation systems are constellations orbiting the Earth and transmitting radio signals for determining position and velocity of users around the globe. The state-of-the-art navigation satellite systems are located in medium Earth orbits and geosynchronous Earth orbits and are characterized by high launching, building and maintenance costs. For applications that require only regional coverage, the continuous and global coverage that existing systems provide may be unnecessary. Thus, a nano-satellites-based regional navigation satellite system in Low Earth Orbit (LEO), with significantly reduced launching, building and maintenance costs, can be considered. Thus, this paper is aimed at developing a LEO constellation optimization and design method, using genetic algorithms and gradient-based optimization. The preliminary results of this study include 268 LEO constellations, aimed at regional navigation in an approximately 1000 km × 1000 km area centered at the geographic coordinates [30, 30] degrees. The constellations performance is examined using simulations, and the figures of merit include total coverage time, revisit time, and geometric dilution of precision (GDOP) percentiles. The GDOP is a quantity that determines the positioning solution accuracy and solely depends on the spatial geometry of the satellites. Whereas the optimization method takes into account only the Earth's second zonal harmonic coefficient, the simulations include the Earth's gravitational field with zonal and tesseral harmonics up to degree 10 and order 10, Solar radiation pressure, drag, and the lunisolar gravitational perturbation.

  9. The esa earth explorer land surface processes and interactions mission (United States)

    Labandibar, Jean-Yves; Jubineau, Franck; Silvestrin, Pierluigi; Del Bello, Umberto


    The European Space Agency (ESA) is defining candidate missions for Earth Observation. In the class of the Earth Explorer missions, dedicated to research and pre-operational demonstration, the Land Surface Processes and Interactions Mission (LSPIM) will acquire the accurate quantitative measurements needed to improve our understanding of the nature and evolution of biosphere-atmosphere interactions and to contribute significantly to a solution of the scaling problems for energy, water and carbon fluxes at the Earth's surface. The mission is intended to provide detailed observations of the surface of the Earth and to collect data related to ecosystem processes and radiation balance. It is also intended to address a range of issues important for environmental monitoring, renewable resources assessment and climate models. The mission involves a dedicated maneuvering satellite which provides multi-directional observations for systematic measurement of Land Surface BRDF (BiDirectional Reflectance Distribution Function) of selected sites on Earth. The satellite carries an optical payload : PRISM (Processes Research by an Imaging Space Mission), a multispectral imager providing reasonably high spatial resolution images (50 m over 50 km swath) in the whole optical spectral domain (from 450 nm to 2.35 μm with a resolution close to 10 nm, and two thermal bands from 8.1 to 9.1 μm). This paper presents the results of the Phase A study awarded by ESA, led by ALCATEL Space Industries and concerning the design of LSPIM.

  10. The Earth System Science Pathfinder VOLCAM Volcanic Hazard Mission (United States)

    Krueger, Arlin J.


    The VOLCAM mission is planned for research on volcanic eruptions and as a demonstration of a satellite system for measuring the location and density of volcanic eruption clouds for use in mitigating hazards to aircraft by the operational air traffic control systems. A requirement for 15 minute time resolution is met by flight as payloads of opportunity on geostationary satellites. Volcanic sulfur dioxide and ash are detected using techniques that have been developed from polar orbiting TOMS (UV) and AVHRR (IR) data. Seven band UV and three band IR filter wheel cameras are designed for continuous observation of the full disk of the earth with moderate (10 - 20 km) ground resolution. This resolution can be achieved with small, low cost instruments but is adequate for discrimination of ash and sulfur dioxide in the volcanic clouds from meteorological clouds and ozone. The false alarm rate is small through use of sulfur dioxide as a unique tracer of volcanic clouds. The UV band wavelengths are optimized to detect very small sulfur dioxide amounts that are present in pre-eruptive outgassing of volcanoes. The system is also capable of tracking dust and smoke clouds, and will be used to infer winds at tropopause level from the correlation of total ozone with potential vorticity.

  11. METRIC: A Dedicated Earth-Orbiting Spacecraft for Investigating Gravitational Physics and the Space Environment (United States)

    Peron, R.; Lorenzini, E. C.


    A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk eccentric orbit between 450 and 1200 km of altitude. The spacecraft will be tracked from the ground with high precision, and a three-axis accelerometer package on-board will measure the non-gravitational accelerations acting on its surface. Estimates of parameters related to fundamental physics and geophysics should be obtained by a precise orbit determination, while the accelerometer data will be instrumental in constraining the atmospheric density. Along with the mission scientific objectives, a conceptual configuration is described together with an analysis of the dynamical environment experienced by the spacecraft and the acc! elerometer.

  12. Fractionated space infrastructure for long-term earth observation missions (United States)

    Chu, Jing; Guo, Jian; Gill, E. K. A.

    A fractionated spacecraft is a space system that distributes its functionalities, such as computation, communication, data storage, payload and even power generation, over several independent satellite modules that share those functionalities through a wireless link. This paper exploits this innovational architecture to design a space infrastructure that is able to accept and support multiple Earth Observation (EO) payload modules. In this paper the functional, physical and organizational architectures of the infrastructure are presented. To start with, EO programs utilizing monolithic spacecraft especially SPOT and Landsat programs are reviewed and analyzed to derive the inherent EO functional requirements. Then these functional requirements are integrated into an EO scenario based on a reference orbit typically for EO missions. Next, novel architectures of fractionated spacecraft are reviewed and the inherent non traditional attributes are summarized and classified in such a way to show their close interrelation with the EO functional requirements. Then four resources components: high bandwidth downlink component, data relay satellite communication component, mission data processor component and large volume data storage component are identified and designated to establish the EO space infrastructure. Based on those four components different physical architectures are designed for the specific scenario and then are evaluated using the Analytical Hierarchy Process (AHP) with eight selection criteria. Afterwards, the best option has been identified, which comprises four heterogeneous modules assigned to host those four resources components separately. Finally, this physical architecture is organized by means of the Multi-Agent System (MAS) theory, which fulfills best the EO non traditional requirements. The proposed organization is tailored for the autonomous operations of the fractionated infrastructure and is based on the peer-to-peer architecture. From a physica

  13. Comet mission hopes to uncover Earth's origins

    CERN Multimedia

    Henderson, M


    "A European spacecraft that will hunt down a comet in search of clues to the origin of life on Earth will blast off tomorrow from the Kourou spaceport in French Guiana. The Rosetta probe will take 12 years to catch up with Churyumov-Gerasimenko before becoming the first spacecraft to make a soft, controlled landing on a comet's nucleus" (1 page).

  14. Low Thrust Mission Trajectories to Near Earth Asteroids (United States)

    Saripalli, Pratik; Cardiff, Eric


    The discovery of 2016 HO3 and its classification as a quasi-satellite has sparked a stronger interest towards Near Earth Asteroids (NEAs). This work presents low-thrust low-power mission designs to various NEAs using an EELV Secondary Payload Adapter (ESPA). A global trajectory optimizer (EMTG) was used to generate mission solutions to a select 13 NEAs using a 200 watt BHT-200 thruster as a proof of concept. The missions presented here demonstrate that a low-cost electric propulsion ESPA mission to NEAs is a feasible concept for many asteroids.

  15. Probing the Earth from space - The Aristoteles mission (United States)

    Schuyer, M.; Silvestrin, P.; Aguirre, M.


    The Aristoteles mission has been under study by the Agency since 1987. Its aim is to provide global models of the Earth's gravitational and magnetic fields with high spatial resolution and accuracy. Following earlier discussions, in 1990 NASA confirmed its intention to participate in the mission with the provision of a dedicated launch and of additional instruments. This has made it possible to enhance the scientific and application-orientated value of the mission and to optimize the spacecraft design. This article reviews the new joint ESA-NASA Aristoteles mission, as well as the status of the system definition and of the associated technological pre-development activities.


    National Aeronautics and Space Administration — Galileo Orbiter 60 second sampled trajectory data from the Earth-2 flyby in GSE and GSM coordinates. These data cover the interval 1992-11-03 to 1992-12-20.


    National Aeronautics and Space Administration — Galileo Orbiter 60 second sampled trajectory data from the Earth-1 flyby in GSE and GSM coordinates. These data cover the interval 1990-11-05 to 1990-12-31.


    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated 20 second averaged data from the Earth-1 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...


    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated 20 second averaged data from the Earth-2 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...


    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Earth-2 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...


    National Aeronautics and Space Administration — Galileo Orbiter Magnetometer (MAG) calibrated high-resolution data from the Earth-1 flyby in spacecraft, GSE, and GSM coordinates. These data cover the interval...

  2. Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond (United States)

    Cottin, Hervé; Kotler, Julia Michelle; Billi, Daniela; Cockell, Charles; Demets, René; Ehrenfreund, Pascale; Elsaesser, Andreas; d'Hendecourt, Louis; van Loon, Jack J. W. A.; Martins, Zita; Onofri, Silvano; Quinn, Richard C.; Rabbow, Elke; Rettberg, Petra; Ricco, Antonio J.; Slenzka, Klaus; de la Torre, Rosa; de Vera, Jean-Pierre; Westall, Frances; Carrasco, Nathalie; Fresneau, Aurélien; Kawaguchi, Yuko; Kebukawa, Yoko; Nguyen, Dara; Poch, Olivier; Saiagh, Kafila; Stalport, Fabien; Yamagishi, Akihiko; Yano, Hajime; Klamm, Benjamin A.


    The space environment is regularly used for experiments addressing astrobiology research goals. The specific conditions prevailing in Earth orbit and beyond, notably the radiative environment (photons and energetic particles) and the possibility to conduct long-duration measurements, have been the main motivations for developing experimental concepts to expose chemical or biological samples to outer space, or to use the reentry of a spacecraft on Earth to simulate the fall of a meteorite. This paper represents an overview of past and current research in astrobiology conducted in Earth orbit and beyond, with a special focus on ESA missions such as Biopan, STONE (on Russian FOTON capsules) and EXPOSE facilities (outside the International Space Station). The future of exposure platforms is discussed, notably how they can be improved for better science return, and how to incorporate the use of small satellites such as those built in cubesat format.

  3. Prevalence of Earth-size planets orbiting Sun-like stars (United States)

    Petigura, Erik A.; Howard, Andrew W.; Marcy, Geoffrey W.


    Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration’s Kepler mission. We found 603 planets, including 10 that are Earth size () and receive comparable levels of stellar energy to that of Earth (). We account for Kepler’s imperfect detectability of such planets by injecting synthetic planet–caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ∼200 d. Extrapolating, one finds % of Sun-like stars harbor an Earth-size planet with orbital periods of 200–400 d. PMID:24191033

  4. Prevalence of Earth-size planets orbiting Sun-like stars. (United States)

    Petigura, Erik A; Howard, Andrew W; Marcy, Geoffrey W


    Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration's Kepler mission. We found 603 planets, including 10 that are Earth size ( ) and receive comparable levels of stellar energy to that of Earth (1 - 2 R[Symbol: see text] ). We account for Kepler's imperfect detectability of such planets by injecting synthetic planet-caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ~200 d. Extrapolating, one finds 5.7(-2.2)(+1.7)% of Sun-like stars harbor an Earth-size planet with orbital periods of 200-400 d.

  5. Biofilms On Orbit and On Earth: Current Methods, Future Needs (United States)

    Vega, Leticia


    Biofilms have played a significant role on the effectiveness of life support hardware on the Space Shuttle and International Space Station (ISS). This presentation will discuss how biofilms impact flight hardware, how on orbit biofilms are analyzed from an engineering and research perspective, and future needs to analyze and utilize biofilms for long duration, deep space missions.

  6. Spacecraft Orbits for Earth/Mars-Lander Radio Relay (United States)

    Noreen, Gary; Diehl, Roger; Neelon, Joseph


    A report discusses a network of spacecraft, in orbit around Mars, used to relay radio communications between Earth stations and mobile exploratory robots (rovers) as well as stationary scientific instruments that have been landed on the Mars surface. The relay spacecraft include two already in orbit plus several others planned to arrive at Mars in the years 2004 through 2008. A major portion of the report is devoted to the orbit of the G. Macroni Orbiter, which is in the midst of an iterative design process and is intended to be the first Mars orbiter designed primarily for radio relay. Candidate orbits are analyzed with a view toward choosing one that maximizes the amount of time available for communication with surface units, taking account of visibility as a function of position, the limit on communication distance at low power, and the fact that surface units can transmit more easily when they are in sunlight. Two promising new orbits for Mars relay satellites are identified: a 1/2-sol apoapsis-at-constant-time-of-day equatorial orbit and a 1/4-sol apoapsis-at-constant-time-of-day, critical-inclination orbit.

  7. Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space (United States)

    Yu, Wayne Hong


    The potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of x-ray photons from millisecond pulsars (MSP) to perform space navigation. By comparing the detected arrival of x-ray photons to a reference database of expected pulsar light-curve timing models, one can infer a range and range rate measurement based on light time delay. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This is a study of potential pulsar XNAV measurements to measure extended Kalman filter (EKF) tracking performance with a wide trade space of bounded Earth orbits, using a simulation of existing x-ray detector space hardware. An example of an x-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in late 2016early 2017. XNAV hardware implementation is driven by trajectory and environmental influences which add noise to the x-ray pulse signal. In a closed Earth orbit, the radiation environment can exponentially increase the signal noise from x-ray pulsar sources, decreasing the quality and frequency of measurements. The SEXTANT mission in particular improves on the signal to noise ratio by focusing an array of 56 x-ray silicon drift detectors at one pulsar target at a time. This reduces timing glitches and other timing noise contributions from ambient x-ray sources to within a 100 nanosecond resolution. This study also considers the SEXTANT scheduling challenges inherent in a single target observation. Finally, as the navigation sources are now relatively inertial targets, XNAV measurements are also subject to periods of occultation from various celestial bodies. This study focuses on the characterization of these drivers in closed Earth orbits and is not a

  8. The Radiation Belt Storm Probes Mission: Advancing Our Understanding of the Earth's Radiation Belts (United States)

    Sibeck, David; Kanekal, Shrikanth; Kessel, Ramona; Fox, Nicola; Mauk, Barry


    We describe NASA's Radiation Belt Storm Probe (RBSP) mission, whose primary science objective is to understand, ideally to the point of predictability, the dynamics of relativistic electrons and penetrating ions in the Earth's radiation belts resulting from variable solar activity. The overarching scientific questions addressed include: 1. the physical processes that produce radiation belt enhancement events, 2. the dominant mechanisms for relativistic electron loss, and 3. how the ring current and other geomagnetic processes affect radiation belt behavior. The RBSP mission comprises two spacecraft which will be launched during Fall 2012 into low inclination lapping equatorial orbits. The orbit periods are about 9 hours, with perigee altitudes and apogee radial distances of 600 km and 5.8 RE respectively. During the two-year primary mission, the spacecraft orbits precess once around the Earth and lap each other twice in each local time quadrant. The spacecraft are each equipped with identical comprehensive instrumentation packages to measure, electrons, ions and wave electric and magnetic fields. We provide an overview of the RBSP mission, onboard instrumentation and science prospects and invite scientific collaboration.

  9. Orbital Express Mission Operations Planning and Resource Management using ASPEN (United States)

    Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Danny


    The Orbital Express satellite servicing demonstrator program is a DARPA program aimed at developing "a safe and cost-effective approach to autonomously service satellites in orbit". The system consists of: a) the Autonomous Space Transport Robotic Operations (ASTRO) vehicle, under development by Boeing Integrated Defense Systems, and b) a prototype modular next-generation serviceable satellite, NEXTSat, being developed by Ball Aerospace. Flexibility of ASPEN: a) Accommodate changes to procedures; b) Accommodate changes to daily losses and gains; c) Responsive re-planning; and d) Critical to success of mission planning Auto-Generation of activity models: a) Created plans quickly; b) Repetition/Re-use of models each day; and c) Guarantees the AML syntax. One SRP per day vs. Tactical team

  10. ESA Earth Observation missions at the service of geoscience (United States)

    Aschbacher, Josef


    The intervention will present ESA's Earth Observation programmes and their relevance to geoscience. ESA's Earth observation missions are mainly grouped into three categories: The Sentinel satellites in the context of the European Copernicus Programme, the scientific Earth Explorers and the meteorological missions. Developments, applications and scientific results for the different mission types will be addressed, along with overall trends and boundary conditions. The Earth Explorers, who form the science and research element of ESA's Living Planet Programme, focus on the atmosphere, biosphere, hydrosphere, cryosphere and Earth's interior. The Earth Explorers also aim at learning more about the interactions between these components and the impact that human activity is having on natural Earth processes. The Sentinel missions provide accurate, timely, long term and uninterrupted data to provide key information services, improving the way the environment is managed, and helping to mitigate the effects of climate change. The operational Sentinel satellites can also be exploited for scientific endeavours. Meteorological satellites help to predict the weather and feature the most mature application of Earth observation. Over the last four decades satellites have been radically improving the accuracy of weather forecasts by providing unique and indispensable input data to numerical computation models. In addition, Essential Climate Variables (ECV) are constantly monitored within ESA's Climate Change Initiative in order to create a long-term record of key geophysical parameters. All of these activities can only be carried out in international cooperation. Accordingly, ESA maintains long-standing partnerships with other space agencies and relevant institutions worldwide. In running its Earth observation programmes, ESA responds to societal needs and challenges as well as to requirements resulting from political priorities, such as the United Nations' Sustainable Development

  11. Benefits of Delay Tolerant Networking for Earth Science Missions (United States)

    Davis, Faith; Marquart, Jane; Menke, Greg


    To date there has been much discussion about the value of Delay Tolerant Networking (DTN) for space missions. Claims of various benefits, based on paper analysis, are good; however a benefits statement with empirical evidence to support is even better. This paper presents potential and actual advantages of using DTN for Earth science missions based on results from multiple demonstrations, conducted by the Communications, Standards, and Technology Laboratory (CSTL) at NASA Goddard Space Flight Center (GSFC). Demonstrations included two flight demonstrations using the Earth Observing Mission 1 (EO-1) and the Near Earth Network (NEN), a ground based demonstration over satellite links to the Internet Router in Space (IRIS) payload on Intelsat-14, and others using the NASA Tracking Data Relay Satellite System (TDRSS). Real and potential findings include increased flexibility and efficiency in science campaigns, reduced latency in a collaborative science scenario, and improved scientist-instrument communication and control.

  12. A Geostationary Earth Orbit Satellite Model Using Easy Java Simulation (United States)

    Wee, Loo Kang; Goh, Giam Hwee


    We develop an Easy Java Simulation (EJS) model for students to visualize geostationary orbits near Earth, modelled using a Java 3D implementation of the EJS 3D library. The simplified physics model is described and simulated using a simple constant angular velocity equation. We discuss four computer model design ideas: (1) a simple and realistic…

  13. MarcoPolo-R near earth asteroid sample return mission


    Michel, P.; Böhnhardt, H.; Campo Bagatin, A.; Cerroni, P.; Dotto, E.; Fitzsimmons, A.; Lara, L.-M.; Licandro, J.; Marty, B.; Muinonen, K.; Nathues, A.; Oberst, J.; Robert, F.; Saladino, R.; Ulamec, S.


    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2 kg) from an organic-rich binary asteroid to Earth for laboratory analyses, allowing us to: explore the origin of planetary materials and...

  14. Mission Adaptive UAS Platform for Earth Science Resource Assessment (United States)

    Dunagan, S.; Fladeland, M.; Ippolito, C.; Knudson, M.


    NASA Ames Research Center has led a number of important Earth science remote sensing missions including several directed at the assessment of natural resources. A key asset for accessing high risk airspace has been the 180 kg class SIERRA UAS platform, providing mission durations of up to 8 hrs at altitudes up to 3 km. Recent improvements to this mission capability are embodied in the incipient SIERRA-B variant. Two resource mapping problems having unusual mission characteristics requiring a mission adaptive capability are explored here. One example involves the requirement for careful control over solar angle geometry for passive reflectance measurements. This challenges the management of resources in the coastal ocean where solar angle combines with sea state to produce surface glint that can obscure the ocean color signal. Furthermore, as for all scanning imager applications, the primary flight control priority to fly the UAS directly to the next waypoint should compromise with the requirement to minimize roll and crab effects in the imagery. A second example involves the mapping of natural resources in the Earth's crust using precision magnetometry. In this case the vehicle flight path must be oriented to optimize magnetic flux gradients over a spatial domain having continually emerging features, while optimizing the efficiency of the spatial mapping task. These requirements were highlighted in several recent Earth Science missions including the October 2013 OCEANIA mission directed at improving the capability for hyperspectral reflectance measurements in the coastal ocean, and the Surprise Valley Mission directed at mapping sub-surface mineral composition and faults, using high-sensitivity magentometry. This paper reports the development of specific aircraft control approaches to incorporate the unusual and demanding requirements to manage solar angle, aircraft attitude and flight path orientation, and efficient (directly geo-rectified) surface and sub

  15. Size Dependence of Dust Distribution around the Earth Orbit

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Takahiro; Takeuchi, Taku [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551 (Japan); Kobayashi, Hiroshi; Ishihara, Daisuke; Kondo, Toru; Kaneda, Hidehiro, E-mail: [Graduate School of Science, Nagoya University, Nagoya, Aichi, 464-8602 (Japan)


    In the solar system, interplanetary dust particles (IDPs) originating mainly from asteroid collisions and cometary activities drift to Earth orbit due to Poynting–Robertson drag. We analyzed the thermal emission from IDPs that was observed by the first Japanese infrared astronomical satellite, AKARI . The observed surface brightness in the trailing direction of the Earth orbit is 3.7% greater than that in the leading direction in the 9 μ m band and 3.0% in the 18 μ m band. In order to reveal dust properties causing leading–trailing surface brightness asymmetry, we numerically integrated orbits of the Sun, the Earth, and a dust particle as a restricted three-body problem including radiation from the Sun. The initial orbits of particles are determined according to the orbits of main-belt asteroids or Jupiter-family comets. Orbital trapping in mean motion resonances results in a significant leading–trailing asymmetry so that intermediate sized dust (∼10–100 μ m) produces a greater asymmetry than zodiacal light. The leading–trailing surface brightness difference integrated over the size distribution of the asteroidal dust is obtained to be 27.7% and 25.3% in the 9 μ m and 18 μ m bands, respectively. In contrast, the brightness difference for cometary dust is calculated as 3.6% and 3.1% in the 9 μ m and 18 μ m bands, respectively, if the maximum dust radius is set to be s {sub max} = 3000 μ m. Taking into account these values and their errors, we conclude that the contribution of asteroidal dust to the zodiacal infrared emission is less than ∼10%, while cometary dust of the order of 1 mm mainly accounts for the zodiacal light in infrared.

  16. Preliminary investigations on a NTP cargo shuttle for earth to moon orbit payload transfer based on a particle bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Raepsaet, X.; Proust, E.; Gervaise, F.; Baraer, L.; Naury, S.; Linet, F.L. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie; Bresson, C.F.; Coriolis, C.C. de; Bergeron, I.T.A.; Bourquin, L.V.; Clech, L.V.; Devaux, L.V.; Chevillot, L.V.; Augier, E.V. [EAMEA, 50 - Cherbourg (France)


    MAPS, a 3-year study program on NTP has recently been launched at CEA following the conclusions of a preliminary scoping study of an NTP system for earth to moon orbit cargo shuttle missions. This paper presents the main results of this scoping study, and gives an outline of the MAPS program. (authors). 5 figs., 11 tabs., 7 refs.

  17. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission.

    Directory of Open Access Journals (Sweden)

    Mingying Huo

    Full Text Available The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.

  18. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission. (United States)

    Huo, Mingying; Zhao, Jun; Xie, Shaobiao; Qi, Naiming


    The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail.

  19. Marco Polo: Near-Earth Object Sample Return Mission (United States)

    Antonieta Barucci, Maria; Yoshikawa, M.; Koschny, D.; Boehnhardt, H.; Brucato, J. R.; Coradini, M.; Dotto, E.; Franchi, I. A.; Green, S. F.; Josset, J. L.; Kawagushi, J.; Michel, P.; Muinonen, K.; Oberst, J.; Yano, H.; Binzel, R. P.; Marco Polo Science Team


    MARCO POLO is a joint European-Japanese sample return mission to a Near-Earth Object (NEO), selected by ESA in the framework of COSMIC VISION 2015-2025 for an assessment study scheduled to last until October 2009. This Euro-Asian mission will go to a primitive Near-Earth Object (NEO), such as C or D-type, scientifically characterize it at multiple scales, and bring samples back to Earth for detailed scientific investigation. NEOs are part of the small body population in the Solar System, which are leftover building blocks of the Solar System formation process. They offer important clues to the chemical mixture from which planets formed about 4.6 billion years ago. The scientific objectives of Marco Polo will therefore contribute to a better understanding of the origin and evolution of the Solar System, the Earth, and the potential contribution of primitive material to the formation of Life. Marco Polo is based on a launch with a Soyuz Fregat and consists of a Mother Spacecraft (MSC), possibly carrying a lander. The MSC would approach the target asteroid and spend a few months for global characterization of the target to select a sampling site. Then, the MSC would then descend to retrieve several samples which will be transferred to a Sample Return Capsule (SRC). The MSC would return to Earth and release the SRC into the atmosphere for ground recovery. The sample of the NEO will then be available for detailed investigation in ground-based laboratories. In parallel to JAXA considering how to perform the mission, ESA has performed a Marco Polo study in their Concurrent Design Facility (CDF). Two parallel industrial studies will start in September 2008 to be conducted in Europe for one year. The scientific objectives addressed by the mission and the current status of the mission study (ESA-JAXA) will be presented and discussed.

  20. Alterations in the heart rate and activity rhythms of three orbital astronauts on a space mission (United States)

    Liu, Zhizhen; Wan, Yufeng; Zhang, Lin; Tian, Yu; Lv, Ke; Li, Yinghui; Wang, Chunhui; Chen, Xiaoping; Chen, Shanguang; Guo, Jinhu


    Environmental factors in space are dramatically different from those on Earth. The spaceflight environment has been known to influence human physiology and behavior on orbital missions. In this study, we investigated alterations in the diurnal rhythms of activity and heart rate of three Chinese astronauts on a space mission. An analysis of the heart rate data showed a significant decrease in heart rate amplitudes during flight in all three subjects. The heart rate amplitudes of all the three astronauts were significantly dampened during flight, and the minimum as well as the maximum value of heart rate increased after flight. A phase shift in heart rate was observed in one of the three astronauts after flight. These results demonstrate the influence of spaceflight on heart physiology and function. In addition, a significant decrease in body trunk activity and rhythmicity occurred during flight, demonstrating that the spaceflight environment disturbs motion adaptation and diurnal activity rhythms.

  1. Spectral properties of near-Earth asteroids on cometary orbits (United States)

    Popescu, M.; Vaduvescu, O.; de Leon, J.; Boaca, I. L.; Gherase, R. M.; Nedelcu, D. A.; INT students, I. N. G.


    We studied the spectral distributions of near-Earth asteroids on cometary orbits (NEACOs) in order to identify potential dormant or extinct comets among these objects. We present the spectral observations for 19 NEACOs obtained with Isaac Newton Telescope and Infrared Telescope Facility (IRTF). Although initially classified as asteroid, one of our targets - 2007 VA85 was confirmed to be active comet 333P/LINEAR on its 2016 appearance. We found that the NEACOs population is a mixing of different compositional classes.

  2. Detection of Several Daemon Populations in Earth-Crossing Orbits (United States)

    Drobyshevski, E. M.; Beloborodyy, M. V.; Kurakin, R. O.; Latypov, V. G.; Pelepelin, K. A.


    Experiments on scintillator-based detection of negative dark electric matter objects, daemons, representing Planckian supermassive (about 2x10 -5 g) particles that were detected in March 2000 as populating near-Earth, almost circular heliocentric orbits (NEACHOs), are being continued. The NEACHO objects hit the Earth with a velocity of about 10-15 km s-1. The results of these and new experiments (April-June 2001) are now being processed, taking into account the difference in scintillation signal shape depending on the magnitude and sign of the velocity of the daemons crossing our detector, which was purposefully made asymmetric with respect to the up-down direction of flight. The data accumulated during the experiment and processed in this way also reveal the presence of, firstly, a high-velocity (about 35-50 km s-1) daemon population whose objects can be related to a population in the Galactic disc and/or that in strongly elongated Earth-crossing heliocentric orbits and, secondly, a low-velocity (about 3-10 km s-1) population in geocentric Earth-surface-crossing orbits whose objects (GESCOs) traverse repeatedly the Earth, suffering a decrease in velocity by about 30-40% month in the process. The evolutionary relation between all these three (four?) populations is discussed. Conjectures concerning their manifestations in further observations are put forward. An analysis of possible interaction processes of daemons, which may have different velocities and directions of motion, with the detector components (ZnS(Ag) scintillator layers, tinned-iron sheets 0.3 mm thick, etc.) on the atomic (emission of Auger electrons) and nuclear (nucleon evaporation from a nucleus excited in the capture and, subsequently, the decay of its protons) levels has permitted estimation of some characteristic times. In particular, the decay time of a daemon-containing proton was found to be about 1 μs.

  3. ESA's Future Earth Explorer: new candidate mission concepts (United States)

    Drinkwater, M.; Ingmann, P.; Kern, M.; Langen, J.; Drusch, M.; Davidson, M.; Bensi, P.; Carnicero, B.; Thompson, A.; Silvestrin, P.; Lin, C.; Heliere, F.; Bezy, J.; Durand, Y.; Aguirre, M.; Haagmans, R.


    The European Space Agency has released the call for the next Earth Explorer Core Mission Ideas in March 2005 with the aim to select the 7th Earth Explorer mission to be launched in the 2014 timeframe. Twenty-four proposals were received and subject to detailed scientific and technical assessment. Six proposals have been selected to be further investigated in a detailed scientific and technical assessment study, after which a down-selection will be made. The six candidate missions selected are: A-SCOPE - (Advanced Space Carbon and Climate Observation of Planet Earth): Improving the understanding of the global carbon cycle and regional carbon dioxide fluxes, BIOMASS - global measurements of forest biomass and extent, CoReH2O - (Cold Regions Hydrology High-resolution Observatory): Detailed observations of key snow, ice and water cycle characteristics, FLEX - (FLuorescence EXplorer): Observation of global photosynthesis through the measurement of fluorescence, PREMIER - (PRocess Exploration through Measurements of Infrared and millimetre- wave Emitted Radiation): Understanding the processes that link trace gases, radiation, chemistry and climate in the atmosphere and TRAQ - (TRopospheric composition and Air Quality) - Air quality monitoring and long-range transport of air pollutants. This paper will give an overview of the science objectives and preliminary requirement specifications for each candidate mission. A user concultation meeting will be held at the Congress Centre of the Belém Cultural Centre in Lisbon, Portugal, on 20-21 January 2009 to proceed with selected ones in feasibility study.

  4. The Lunar Orbiter Laser Altimeter (LOLA) on NASA's Lunar Reconnaissance Orbiter (LRO) mission (United States)

    Riris, H.; Cavanaugh, J.; Sun, X.; Liiva, P.; Rodriguez, M.; Neuman, G.


    The Lunar Orbiter Laser Altimeter (LOLA) instrument [1-3] on NASA's Lunar Reconnaissance Orbiter (LRO) mission, launched on June 18th, 2009, from Kennedy Space Center, Florida, will provide a precise global lunar topographic map using laser altimetry. LOLA will assist in the selection of landing sites on the Moon for future robotic and human exploration missions and will attempt to detect the presence of water ice on or near the surface, which is one of the objectives of NASA's Exploration Program. Our present knowledge of the topography of the Moon is inadequate for determining safe landing areas for NASA's future lunar exploration missions. Only those locations, surveyed by the Apollo missions, are known with enough detail. Knowledge of the position and characteristics of the topographic features on the scale of a lunar lander are crucial for selecting safe landing sites. Our present knowledge of the rest of the lunar surface is at approximately 1 km kilometer level and in many areas, such as the lunar far side, is on the order of many kilometers. LOLA aims to rectify that and provide a precise map of the lunar surface on both the far and near side of the moon. LOLA uses short (6 ns) pulses from a single laser through a Diffractive Optical Element (DOE) to produce a five-beam pattern that illuminates the lunar surface. For each beam, LOLA measures the time of flight (range), pulse spreading (surface roughness), and transmit/return energy (surface reflectance). LOLA will produce a high-resolution global topographic model and global geodetic framework that enables precise targeting, safe landing, and surface mobility to carry out exploratory activities. In addition, it will characterize the polar illumination environment, and image permanently shadowed regions of the lunar surface to identify possible locations of surface ice crystals in shadowed polar craters.

  5. International Space Station as a base camp for exploration beyond low Earth orbit (United States)

    Raftery, Michael; Hoffman, Jeffrey


    The idea for using the International Space Station (ISS) as a platform for exploration has matured in the past few years and the concept continues to gain momentum. ISS provides a robust infrastructure which can be used to test systems and capabilities needed for missions to the Moon, Mars, asteroids and other potential destinations. International cooperation is a critical enabler and ISS has already demonstrated successful management of a large multi-national technical endeavor. Systems and resources needed for expeditions can be aggregated and thoroughly tested at ISS before departure thus providing wide operational flexibility and the best assurance of mission success. A small part of ISS called an Exploration Platform (ISS-EP) can be placed in cislunar space providing immediate benefits and flexibility for future exploration missions. We will show how ISS and the ISS-EP can be used to reduce risk and improve the operational flexibility for missions beyond low Earth orbit. Life support systems and other technologies developed for ISS can be evolved and adapted to the ISS-EP and other exploration spacecrafts. New technology, such as electric propulsion and advanced life support systems can be tested and proven at ISS as part of an incremental development program. Commercial companies who are introducing transportation and other services will benefit with opportunities to contribute to the mission since ISS will serve as a focal point for the commercialization of low earth orbit services. Finally, we will show how the use of ISS provides immediate benefits to the scientific community because its capabilities are available today and certain critical aspects of exploration missions can be simulated.

  6. Analogue Missions on Earth, a New Approach to Prepare Future Missions on the Moon (United States)

    Lebeuf, Martin

    Human exploration of the Moon is a target by 2020 with an initial lunar outpost planned in polar regions. Current architectures maintain a capability for sorties to other latitudes for science activities. In the early stages of design of lunar outpost infrastructure and science activity planning, it has been recognized that analogue missions could play a major role in Moon mission design. Analogue missions, as high fidelity simulations of human and robotic surface operations, can help field scientists and engineers develop and test strategies as well as user requirements, as they provide opportunities to groundtruth measurements, and for the team to share understanding of key science needs and key engineering trades. These types of missions also provide direct training in planning science operations, and in team building and communication. The Canadian Space Agency's Exploration Core Program targets the development of technology infrastructure elements in key areas of science, technology and robotics in preparation for its role in the future exploration of the Moon and Mars. Within this Program, Analogue Missions specifically target the operations requirements and lessons learned that will reduce costs and lower the risk of planetary surface missions. Analogue missions are simulations of planetary surface operations that take place at analogue sites on Earth. A terrestrial analogue site resembles in some key way: eg. geomorphologically or geochemically, a surface environment of another planet. An analogue mission can, therefore, be defined as an integrated set of activities that represent (or simulate) entire mission designs or narrowly focus on specific aspects of planned or potential future planetary exploration missions. Within the CSA's Exploration Core Program, Analogue Missions facilitate the maturation of science instruments and mission concepts by integrating ongoing space instrument and technology development programs with science and analogue elements. As

  7. Radiation Dose Analysis of Galactic Cosmic Ray in Low Earth Orbit/Near Equatorial Orbit (United States)

    Suparta, W.; Zulkeple, S. K.


    Space environment contained harmful radiation that posed risk to spacecraft orbiting the Earth. In this paper, we looked into radiation doses caused by galactic cosmic ray (GCR) towards satellites orbiting in low earth orbit (LEO) near Earth's equator (NEqO) and compared them with doses caused by solar energetic particles (SEP) and trapped particles to determine the damage level of GCR. The radiation doses included linear energy transfer (LET) and nonionizing energy loss (NIEL) through a 1mm gallium arsenide (GaAs) planar geometry by using Space Environment Information System (SPENVIS) method. The orbital data followed Malaysian Razaksat satellite at 685km altitude and 9° inclination during selected solar minimum and solar maximum from solar cycles 21 to 24. We found that trapped particles gave the highest LET and no SEP was detected in SPENVIS. The LET values tend to be higher during solar minimum for trapped particles and GCR, corresponding to their anti-correlated fluxes with the solar activity. However, the NIEL values for GCR in solar cycle 23 did not follow the anti-correlation pattern.

  8. ARISTOTELES: A European approach for an Earth gravity field recovery mission (United States)

    Benz, R.; Faulks, H.; Langemann, M.


    Under contract of the European Space Agency a system study for a spaceborne gravity field recovery mission was performed, covering as a secondary mission objective geodetic point positioning in the cm range as well. It was demonstrated that under the given programmatic constraints including dual launch and a very tight development schedule, a six months gravity field mission in a 200 km near polar, dawn-dusk orbit is adequate to determine gravity anomalies to better than 5 mgal with a spatial resolution of 100 x 100 km half wavelength. This will enable scientists to determine improved spherical harmonic coefficients of the Earth gravity field equation to the order and degree of 180 or better.

  9. Small Solar Electric Propulsion Spacecraft Concept for Near Earth Object and Inner Solar System Missions (United States)

    Lang, Jared J.; Randolph, Thomas M.; McElrath, Timothy P.; Baker, John D.; Strange, Nathan J.; Landau, Damon; Wallace, Mark S.; Snyder, J. Steve; Piacentine, Jamie S.; Malone, Shane; hide


    Near Earth Objects (NEOs) and other primitive bodies are exciting targets for exploration. Not only do they provide clues to the early formation of the universe, but they also are potential resources for manned exploration as well as provide information about potential Earth hazards. As a step toward exploration outside Earth's sphere of influence, NASA is considering manned exploration to Near Earth Asteroids (NEAs), however hazard characterization of a target is important before embarking on such an undertaking. A small Solar Electric Propulsion (SEP) spacecraft would be ideally suited for this type of mission due to the high delta-V requirements, variety of potential targets and locations, and the solar energy available in the inner solar system.Spacecraft and mission trades have been performed to develop a robust spacecraft design that utilizes low cost, off-the-shelf components that could accommodate a suite of different scientific payloads for NEO characterization. Mission concepts such as multiple spacecraft each rendezvousing with different NEOs, single spacecraft rendezvousing with separate NEOs, NEO landers, as well as other inner solar system applications (Mars telecom orbiter) have been evaluated. Secondary launch opportunities using the Expendable Secondary Payload Adapter (ESPA) Grande launch adapter with unconstrained launch dates have also been examined.

  10. Low-earth-orbit Satellite Internet Protocol Communications Concept and Design (United States)

    Slywezak, Richard A.


    This report presents a design concept for a low-Earth-orbit end-to-end Internet-Protocol- (IP-) based mission. The goal is to maintain an up-to-date communications infrastructure that makes communications seamless with the protocols used in terrestrial computing. It is based on the premise that the use of IPs will permit greater interoperability while also reducing costs and providing users the ability to retrieve data directly from the satellite. However, implementing an IP-based solution also has a number of challenges, since wireless communications have different characteristics than wired communications. This report outlines the design of a low-Earth-orbit end-to-end IP-based mission; the ideas and concepts of Space Internet architectures and networks are beyond the scope of this document. The findings of this report show that an IP-based mission is plausible and would provide benefits to the user community, but the outstanding issues must be resolved before a design can be implemented.

  11. Plasma Flowfields Around Low Earth Orbit Objects: Aerodynamics to Underpin Orbit Predictions (United States)

    Capon, Christopher; Boyce, Russell; Brown, Melrose


    Interactions between orbiting bodies and the charged space environment are complex. The large variation in passive body parameters e.g. size, geometry and materials, makes the plasma-body interaction in Low Earth Orbit (LEO) a region rich in fundamental physical phenomena. The aerodynamic interaction of LEO orbiting bodies with the neutral environment constitutes the largest non-conservative force on the body. However in general, study of the LEO plasma-body interaction has not been concerned with external flow physics, but rather with the effects on surface charging. The impact of ionospheric flow physics on the forces on space debris (and active objects) is not well understood. The work presented here investigates the contribution that plasma-body interactions have on the flow structure and hence on the total atmospheric force vector experienced by a polar orbiting LEO body. This work applies a hybrid Particle-in-Cell (PIC) - Direct Simulation Monte Carlo (DSMC) code, pdFoam, to self-consistently model the electrostatic flowfield about a cylinder with a uniform, fixed surface potential. Flow conditions are representative of the mean conditions experienced by the Earth Observing Satellite (EOS) based on the International Reference Ionosphere model (IRI-86). The electron distribution function is represented by a non-linear Boltzmann electron fluid and ion gas-surface interactions are assumed to be that of a neutralising, conducting, thermally accommodating solid wall with diffuse reflections. The variation in flowfield and aerodynamic properties with surface potential at a fixed flow condition is investigated, and insight into the relative contributions of charged and neutral species to the flow physics experienced by a LEO orbiting body is provided. This in turn is intended to help improve the fidelity of physics-based orbit predictions for space debris and other near-Earth space objects.

  12. Low-thrust transfers from distant retrograde orbits to L2 halo orbits in the earth-moon system

    NARCIS (Netherlands)

    Parrish, N.L.; Parker, Jeffrey S.; Hughes, S.P.; Heiligers, M.J.


    Enable future missions Any mission to a DRO or halo orbit could benefit from the capability to transfer between these orbits Chemical propulsion could be used for these transfers, but at high propellant cost Fill gaps in knowledge A variety of transfers using SEP or solar sails have been studied for

  13. Effects of CubeSat Deployments in Low-Earth Orbit (United States)

    Matney, M. J.; Vavrin, A. B.; Manis, A. P.


    Long-term models, such as NASA's LEGEND (LEO (Low-Earth Orbit)-to-GEO (Geosynchrous Earth Orbit) Environment Debris) model, are used to make predictions about how space activities will affect the long-term evolution of the debris environment. Part of this process is to predict how spacecraft and rocket bodies will be launched and left in the environment in the future. This has usually been accomplished by repeating past launch history to simulate future launches. It was partially upon the basis of the results of such models that both national and international orbital debris mitigation guidelines - especially the "25-year rule" for post-mission disposal - were determined. The proliferation of Cubesat launches in recent years, however, has raised concerns that we are seeing a fundamental shift in how humans launch satellites into space that may alter the assumptions upon which our current mitigation guidelines are based. The large number of Cubesats, and their short lifetime and general inability to perform collision avoidance, potentially makes them an important new source of debris. The NASA Orbital Debris Program Office (ODPO) has conducted a series of LEGEND computations to investigate the long-term effects of adding Cubesats to the environment. Several possible future scenarios were simulated to investigate the effects of the size of future Cubesat launches and the efficiency of post-mission disposal on the proliferation of catastrophic collisions over the next 200 years. These results are compared to a baseline "business-as-usual" scenario where launches are assumed to continue as in the past without major Cubesat deployments. Using these results, we make observations about the continued use of the 25-year rule and the importance of the universal application of post-mission disposal. We also discuss how the proliferation of Cubesats may affect satellite traffic at lower altitudes.

  14. An international approach to Mission to Planet Earth (United States)

    Lawrence, Robert M.; Sadeh, Willy Z.; Tsygichko, Viktor N.


    The new international political constellation resulting from the disintegration of the Soviet Union opens up unique opportunities for cooperation in the space arena. Precedents since 1955 indicate a pervasive interest in mutual cooperation to use military reconnaissance and surveillance satellites for space observations to enforce treaty verification and compliance. One of the avenues that offer immediate prospects for fruitful cooperation is the incorporation of the military reconnaissance and surveillance satellite capabilities of both U.S. and Russia into the Mission to Planet Earth. Formation of a United Nations Satellite (UNSAT) fleet drawn from the American and Russian space assets is proposed. The role of UNSAT is to provide world wide monitoring of both military and enviromental activities under the umbrella of the Mission to Planet Earth.

  15. Titan Saturn System Mission (TSSM) Enables Comparative Climatology with Earth (United States)

    Reh, Kim; Lunine, J.; Coustenis, A.; Matson, D.; Beauchamp, P.; Erd, C.; Lebreton, J.


    Titan is a complex world more like the Earth than any other: it has a dense mostly nitrogen atmosphere and active climate and meteorological cycles where the working fluid, methane, behaves under Titan conditions the way that water does on Earth. Its geology, from lakes and seas to broad river valleys and mountains, while carved in ice is, in its balance of processes, again most like Earth. Beneath this panoply of Earth-like processes an ice crust floats atop what appears to be a liquid water ocean. The Titan Saturn System Mission would seek to understand Titan as a system, in the same way that one would ask this question about Venus, Mars, and the Earth. How are distinctions between Titan and other worlds in the solar systems understandable in the context of the complex interplay of geology, hydrology, meteorology, and aeronomy? Is Titan an analogue for some aspect of Earth's history, past or future? Why is Titan endowed with an atmosphere when Ganymede is not? Titan is also rich in organic molecules_more so in its surface and atmosphere than anyplace in the solar system, including Earth (excluding our vast carbonate sediments). These molecules were formed in the atmosphere, deposited on the surface and, in coming into contact with liquid water may undergo an aqueous chemistry that could replicate aspects of life's origins. The second goal of the proposed TSSM mission is to understand the chemical cycles that generate and destroy organics and assess the likelihood that they can tell us something of life's origins. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA.

  16. Military Space Mission Design and Analysis in a Multi-Body Environment: An Investigation of High-Altitude Orbits as Alternative Transfer Paths, Parking Orbits for Reconstitution, and Unconventional Mission Orbits (United States)



  17. Solar Sailing Kinetic Energy Interceptor (KEI) Mission for Impacting/Deflecting Near-Earth Asteroids (United States)

    Wie, Bong


    A solar sailing mission architecture, which requires a t least ten 160-m, 300-kg solar sail spacecraft with a characteristic acceleration of 0.5 mm/sqs, is proposed as a realistic near- term option for mitigating the threat posed by near-Earth asteroids (NEAs). Its mission feasibility is demonstrated for a fictional asteroid mitigation problem created by AIAA. This problem assumes that a 200-m asteroid, designated 2004WR, was detected on July 4, 2004, and that the expected impact will occur on January 14, 2015. The solar sailing phase of the proposed mission for the AIAA asteroid mitigation problem is comprised of the initial cruise phase from 1 AU t o 0.25 AU (1.5 years), the cranking orbit phase (3.5 years), and the retrograde orbit phase (1 year) prior to impacting the target asteroid at its perihelion (0.75 AU from the sun) on January 1, 2012. The proposed mission will require at least ten kinetic energy interceptor (KEI) solar sail spacecraft. Each KEI sailcraft consists of a 160- m, 150-kg solar sail and a 150-kg microsatellite impactor. The impactor is to be separated from a large solar sail prior to impacting the 200-m target asteroid at its perihelion. Each 150-kg microsatellite impactor, with a relative impact velocity of at least 70 km/s, will cause a conservatively estimated AV of 0.3 cm/s in the trajectory of the 200-m target asteroid, due largely to the impulsive effect of material ejected from the newly-formed crater. The deflection caused by a single impactor will increase the Earth-miss-distance by 0.45Re (where Re denotes the Earth radius of 6,378 km). Therefore, at least ten KEI sailcraft will be required for consecutive impacts, but probably without causing fragmentation, to increase the total Earth-miss-distance by 4.5Re. This miss-distance increase of 29,000 km is outside of a typical uncertainty/error of about 10,000 km in predicting the Earth-miss- distance. A conventional Delta I1 2925 launch vehicle is capable of injecting at least two KEI

  18. Exploring the challenges of habitation design for extended human presence beyond low-earth orbit: Are new requirements and processes needed?

    NARCIS (Netherlands)

    Robinson, D.K.R.; Sterenborg, Glenn; Häuplik, Sandra; Aguzzi, Manuela


    With the renewed interest in a sustained human presence beyond low-earth orbit, habitation in space, on planets and on moons is an area that requires re-evaluation in terms of mission and habitat design—there is a need for a paradigmatic move from a design focus on short-term LEO missions to that of

  19. Are artificial satellites orbits influenced by an expanding Earth?

    Directory of Open Access Journals (Sweden)

    G. Scalera


    Full Text Available Albeit in the past great theoretical and experimental efforts were made in proposing and searching for G time-decreasing, a major role could be played by an increase of M. A recent analysis (Scalera, 2003a converges toward an upper limit of the Earth’s mass variation in the order of magnitude of M/M=10-9 /yr. It is here discussed the possible role that can be played by parameters linked to the expanding Earth in the effects we observe in the orbital motion of the artificial satellites. The important result in this short note is the discrimination between the reality of the glacial rebound process and/or the relaxation of the 100m excess of equatorial bulge testified by the high rate of j2 , and the improbable role that glacial rebound can have in driving PM and TPW. It is recommended that the new technology of drag-free satellites be used (Gravity-Probe B is the first step to reveal possible residual orbital parameter variations ascribable to formerly unrecognized fictitious drag terms due to Earth radial increase.

  20. Advantages of High vs. Low Earth Orbit for SIRTF (United States)

    Eisenhardt, Peter; Werner, Michael W.


    While the subject of this workshop, which we will refer to as ET (for Enlightenment Telescope), is a dazzling successor to the Hubble Space Telescope, its location is unlikely to be the Low Earth Orbit (LEO) used by HST. Locations suggested for ET include High Earth Orbit (HEO) and the moon. The first space telescope to occupy HEO will be the liquid helium cooled Space Infrared Telescope Facility (SIRTF). The selection of HEO for SIRTF was the outcome of a recent study led by the Ames Research Center which showed significant advantages for SIRTF in HEO vs. LEO. This article summarizes the main results of that study. We begin with a review of SIRTF's rationale and requirements, in part because the IR capabilities and low temperature proposed for ET make it something of a successor to SIRTF as well as to HST. We conclude with some comments about another possible location for both SIRTF and ET, the Earth-Sun L2 Lagrangian point.

  1. Nickel hydrogen low Earth orbit test program update and status (United States)

    Badcock, C. C.; Donley, S. W.; Felts, A. B.; Haag, R. L.


    The current status of nickel-hydrogen (NiH2) testing ongong at NWSC, Crane In, and The Aerospace Corporation, El Segundo, Ca are described. The objective of this testing is to develop a database for NiH2 battery use in Low Earth Orbit (LEO) and support applications in Medium Altitude Orbit (MAO). Individual pressure vessel-type cells are being tested. A minimum of 200 cells (3.5 in diameter and 4.5 in diameter) are included in the test, from four U.S. vendors. As of this date (Nov. 18, 1986) approximately 60 cells have completed preliminary testing (acceptance, characterization, and environmental testing) and have gone into life cycling.

  2. Solar radiation pressure resonances in Low Earth Orbits (United States)

    Alessi, Elisa Maria; Schettino, Giulia; Rossi, Alessandro; Valsecchi, Giovanni B.


    The aim of this work is to highlight the crucial role that orbital resonances associated with solar radiation pressure can have in Low Earth Orbit. We review the corresponding literature, and provide an analytical tool to estimate the maximum eccentricity which can be achieved for well-defined initial conditions. We then compare the results obtained with the simplified model with the results obtained with a more comprehensive dynamical model. The analysis has important implications both from a theoretical point of view, because it shows that the role of some resonances was underestimated in the past, and also from a practical point of view in the perspective of passive deorbiting solutions for satellites at the end-of-life.

  3. A Comparison of Damaging Meteoroid and Orbital Debris Fluxes in Earth Orbit (United States)

    Cooke, William; Matney, Mark; Moorhead, Althea V.; Vavrin, Andrew


    Low Earth orbit is populated with a substantial amount of orbital debris, and it is usually assumed that the flux from these objects contributes to most of the hypervelocity particle risk to spacecraft in this region. The meteoroid flux is known to be dominant at very low altitudes (less than 300 km), where atmospheric drag rapidly removes debris, and at very high altitudes (beyond geostationary), where debris is practically non-existent. The vagueness of these boundaries and repeated questions from spacecraft projects have prompted this work, in which we compare the fluxes of meteoroids and orbital debris capable of producing a millimeter-deep crater in aluminum for circular orbits with altitudes ranging from the top of the atmosphere to 100,000 km. The outputs from the latest NASA debris and meteoroid models, ORDEM 3.0 and MEMR2, are combined with the modified Cour-Palais ballistic limit equation to make a realistic evaluation of the damage-capable particle fluxes, thereby establishing the relative contributions of hazardous debris and meteoroids throughout near-Earth space.

  4. Space tourism: from earth orbit to the moon (United States)

    Collins, P.

    Travel to and from the lunar surface has been known to be feasible since it was first achieved 34 years ago. Since that time there has been enormous progress in related engineering fields such as rocket propulsion, materials and avionics, and about 1 billion has been spent on lunar science and engineering research. Consequently there are no fundamental technical problems facing the development of lunar tourism - only business and investment problems. The outstanding problem is to reduce the cost of launch to low Earth orbit. Recently there has been major progress towards overturning the myth that launch costs are high because of physical limits. Several "X Prize" competitor vehicles currently in test-flight are expected to be able to perform sub-orbital flights at approximately 1/1,000 of the cost of Alan Shepard's similar flight in 1961. This activity could have started 30 years ago if space agencies had had economic rather than political objectives. A further encouraging factor is that the demand for space tourism seems potentially limitless. Starting with sub-orbital flights and growing through orbital activities, travel to the Moon will offer further unique attractions. In every human culture there is immense interest in the Moon arising from millennia of myths. In addition, bird-like flying sports, first described by Robert Heinlein, will become another powerful demand factor. Roundtrips of 1 to 2 weeks are very convenient for travel companies; and the radiation environment will permit visitors several days of surface activity without significant health risks. The paper also discusses economic aspects of lunar tourism, including the benefits it will have for those on Earth. Lunar economic development based on tourism will have much in common with economic development on Earth based on tourism: starting from the fact that many people spontaneously wish to visit popular places, companies in the tourism industry invest to sell a growing range of services to ever

  5. Materials resistance to low earth orbit environmental effects (United States)

    Pippin, H. G.; Torre, L. P.; Linton, R. G.; Whitaker, A. F.


    A number of flexible polymeric materials have been considered as condidates for protective coatings on Kapton film. These coatings have been tested under a variety of environments, each of which simulates one or more aspects of the low earth orbit space environment. Mass loss rates vs fluence and temperatue, optical properties, and surface characteristics under exposure to the various environments will be presented. Kinetics data on Kapton and other materials is interpreted in terms of bond strengths and relative thermodynamic stabilities of potential products. Activation energy for degradation of Kapton by oxygen atoms was determined to be 30 + or - 5 kJ/mol. Materials tested include silicones, fluorosilicones, fluorophosphazenes, fluorocarbons, and hydrocarbons.

  6. MarcoPolo-R near earth asteroid sample return mission (United States)

    Barucci, Maria Antonietta; Cheng, A. F.; Michel, P.; Benner, L. A. M.; Binzel, R. P.; Bland, P. A.; Böhnhardt, H.; Brucato, J. R.; Campo Bagatin, A.; Cerroni, P.; Dotto, E.; Fitzsimmons, A.; Franchi, I. A.; Green, S. F.; Lara, L.-M.; Licandro, J.; Marty, B.; Muinonen, K.; Nathues, A.; Oberst, J.; Rivkin, A. S.; Robert, F.; Saladino, R.; Trigo-Rodriguez, J. M.; Ulamec, S.; Zolensky, M.


    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2 kg) from an organic-rich binary asteroid to Earth for laboratory analyses, allowing us to: explore the origin of planetary materials and initial stages of habitable planet formation; identify and characterize the organics and volatiles in a primitive asteroid; understand the unique geomorphology, dynamics and evolution of a binary NEA. This project is based on the previous Marco Polo mission study, which was selected for the Assessment Phase of the first round of Cosmic Vision. Its scientific rationale was highly ranked by ESA committees and it was not selected only because the estimated cost was higher than the allotted amount for an M class mission. The cost of MarcoPolo-R will be reduced to within the ESA medium mission budget by collaboration with APL (John Hopkins University) and JPL in the NASA program for coordination with ESA's Cosmic Vision Call. The baseline target is a binary asteroid (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return. The choice of this target will allow new investigations to be performed more easily than at a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible at a single object. Several launch windows have been identified in the time-span 2020-2024. A number of other possible primitive single targets of high scientific interest have been identified covering a wide range of possible launch dates. The baseline mission scenario of MarcoPolo-R to 1996 FG3 is as follows: a single primary spacecraft provided by ESA, carrying

  7. Energy Balance and Power Performance Analysis for Satellite in Low Earth Orbit

    Directory of Open Access Journals (Sweden)

    Sung-Soo Jang


    Full Text Available The electrical power system (EPS of Korean satellites in low-earth-orbit is designed to achieve energy balance based on a one-orbit mission scenario. This means that the battery has to be fully charged at the end of a one-orbit mission. To provide the maximum solar array (SA power generation, the peak power tracking (PPT method has been developed for a spacecraft power system. The PPT is operated by a software algorithm, which tracks the peak power of the SA and ensures the battery is fully charged in one orbit. The EPS should be designed to avoid the stress of electronics in order to handle the main bus power from the SA power. This paper summarizes the results of energy balance to achieve optimal power sizing and the actual trend analysis of EPS performance in orbit. It describes the results of required power for the satellite operation in the worst power conditions at the end-of-life, the methods and input data used in the energy balance, and the case study of energy balance analyses for the normal operation in orbit. Both 10:35 AM and 10:50 AM crossing times are considered, so the power performance in each case is analyzed with the satellite roll maneuver according to the payload operation concept. In addition, the data transmission to the Korea Ground Station during eclipse is investigated at the local-time-ascending-node of 11:00 AM to assess the greatest battery depth-of-discharge in normal operation.

  8. Cost-effective and robust mitigation of space debris in low earth orbit (United States)

    Walker, R.; Martin, C.

    It is predicted that the space debris population in low Earth orbit (LEO) will continue to grow and in an exponential manner in the long-term due to an increasing rate of collisions between large objects, unless internationally-accepted space debris mitigation measures are adopted soon. Such measures are aimed at avoiding the future generation of space debris objects and primarily need to be effective in preventing significant long-term growth in the debris population, even in the potential scenario of an increase in future space activity. It is also important that mitigation measures can limit future debris population levels, and therefore the underlying collision risk to space missions, to the lowest extent possible. However, for their wide acceptance, the cost of implementation associated with mitigation measures needs to be minimised as far as possible. Generally, a lower collision risk will cost more to achieve and vice versa, so it is necessary to strike a balance between cost and risk in order to find a cost-effective set of mitigation measures. In this paper, clear criteria are established in order to assess the cost-effectiveness of space debris mitigation measures. A full cost-risk-benefit trade-off analysis of numerous mitigation scenarios is presented. These scenarios consider explosion prevention and post-mission disposal of space systems, including de-orbiting to limited lifetime orbits and re-orbiting above the LEO region. The ESA DELTA model is used to provide long-term debris environment projections for these scenarios as input to the benefit and risk parts of the trade-off analysis. Manoeuvre requirements for the different post-mission disposal scenarios were also calculated in order to define the cost-related element. A 25-year post-mission lifetime de-orbit policy, combined with explosion prevention and mission-related object limitation, was found to be the most cost-effective solution to the space debris problem in LEO. This package would also

  9. Two Earth-sized planets orbiting Kepler-20. (United States)

    Fressin, Francois; Torres, Guillermo; Rowe, Jason F; Charbonneau, David; Rogers, Leslie A; Ballard, Sarah; Batalha, Natalie M; Borucki, William J; Bryson, Stephen T; Buchhave, Lars A; Ciardi, David R; Désert, Jean-Michel; Dressing, Courtney D; Fabrycky, Daniel C; Ford, Eric B; Gautier, Thomas N; Henze, Christopher E; Holman, Matthew J; Howard, Andrew; Howell, Steve B; Jenkins, Jon M; Koch, David G; Latham, David W; Lissauer, Jack J; Marcy, Geoffrey W; Quinn, Samuel N; Ragozzine, Darin; Sasselov, Dimitar D; Seager, Sara; Barclay, Thomas; Mullally, Fergal; Seader, Shawn E; Still, Martin; Twicken, Joseph D; Thompson, Susan E; Uddin, Kamal


    Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R(⊕)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R(⊕)) and the other smaller than the Earth (0.87R(⊕)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.

  10. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets. (United States)

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M


    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary.

  11. How Many Ultra-Low Delta-v Near Earth Objects Remain Undiscovered? Implications for missions. (United States)

    Elvis, Martin; Ranjan, Sukrit; Galache, Jose Luis; Murphy, Max


    The past decade has witnessed considerable growth of interest in missions to Near-Earth Objects (NEOs). NEOs are considered prime targets for manned and robotic missions, for both scientific objectives as well as in-situ resource utilization including harvesting of water for propellant and life support and mining of high-value elements for sale on Earth. Appropriate targets are crucial to such missions. Hence, ultra-low delta-v mission targets are strongly favored. Some mission architectures rely on the discovery of more ultra-low delta-v NEOs. In fact the approved and executed NEO missions have all targeted asteroids with ultra-low LEO to asteroid rendezvous delta-v delta-v, and how many remain to be discovered in various size ranges down to ~100m. We couple the NEOSSat-1 model (Greenstreet et al., 2012) to the NEO size distribution derived from the NEOWISE survey (Mainzer et al., 2011b) to compute an absolute NEO population model. We compare the Minor Planet Center (MPC) catalog of known NEOs to this NEO population model. We compute the delta-v from LEO to asteroid rendezvous orbits using a modified Shoemaker-Helin (S-H) formalism that empirically removes biases found comparing S-H with the results from NHATS. The median delta-v of the known NEOs is 7.3 km/s, the median delta-v predicted by our NEO model is 9.8 km/s, suggesting that undiscovered objects are biased to higher delta-v. The survey of delta-v 300 m. However, there are tens of thousands of objects with delta-v delta-v delta-v) mission targets is limited given current propulsion technology. Visiting the full range of NEO sub-types will likely require improved propulsion systems.

  12. Instrumental background in gamma-ray spectrometers flown in low earth orbit (United States)

    Gehrels, Neil


    Techniques are presented for calculating the instrumental continuum background in gamma-ray spectrometers flown in low earth orbit (LEO), with special attention given to simple methods developed for scaling from the better-understood measurements and calculations of background in balloon-borne instruments to LEO (Gehrels, 1985). Results are presented in the form of predictions of the background and its components for spectrometers in LEO. These predictions are compared to the measured background for the HEAO 3 gamma-ray spectrometer (Mahoney et al., 1980), and predictions are made for the International Gamma-Ray Astrophysics Laboratory mission and the Nuclear Astrophysics Explorer (Matteson et al., 1990) spectrometers. A comparison is made of various orbit options. It is shown that a critical factor is the number of times the instrument passes through the South Atlantic Anomaly (which is the region of enhanced trapped particle fluxes in LEO) and the depth of penetration on each pass.

  13. ADCS controllers comparison for small satellitess in Low Earth Orbit (United States)

    Calvo, Daniel; Laverón-Simavilla, Ana; Lapuerta, Victoria


    Fuzzy logic controllers are flexible and simple, suitable for small satellites Attitude Determination and Control Subsystems (ADCS). In a previous work, a tailored Fuzzy controller was designed for a nanosatellite. Its performance and efficiency were compared with a traditional Proportional Integrative Derivative (PID) controller within the same specific mission. The orbit height varied along the mission from injection at around 380 km down to 200 km height, and the mission required pointing accuracy over the whole time. Due to both, the requirements imposed by such a low orbit, and the limitations in the power available for the attitude control, an efficient ADCS is required. Both methodologies, fuzzy and PID, were fine-tuned using an automated procedure to grant maximum efficiency with fixed performances. The simulations showed that the Fuzzy controller is much more efficient (up to 65% less power required) in single manoeuvres, achieving similar, or even better, precision than the PID. The accuracy and efficiency improvement of the Fuzzy controller increase with orbit height because the environmental disturbances decrease, approaching the ideal scenario. However, the controllers are meant to be used in a vast range of situations and configurations which exceed those used in the calibration process carried out in the previous work. To assess the suitability and performance of both controllers in a wider framework, parametric and statistical methods have been applied using the Monte Carlo technique. Several parameters have been modified randomly at the beginning of each simulation: the moments of inertia of the whole satellite and of the momentum wheel, the residual magnetic dipole and the initial conditions of the test. These parameters have been chosen because they are the main source of uncertainty during the design phase. The variables used for the analysis are the error (critical for science) and the operation cost (which impacts the mission lifetime and

  14. Navigation Support at JPL for the JAXA Akatsuki (PLANET-C) Venus Orbiter Mission (United States)

    Ryne, Mark S.; Mottinger, Neil A.; Broschart, Stephen B.; You, Tung-Han; Higa, Earl; Helfrich, Cliff; Berry, David


    This paper details the orbit determination activities undertaken at JPL in support of the Japanese Aerospace Exploration Agency's (JAXA) Akatsuki (a.k.a. Plan-et-C and/or Venus Climate Orbiter) mission. The JPL navigation team's role was to provide independent navigation support as a point of comparison with the JAXA generated orbit determination solutions. Topics covered include a mis-sion and spacecraft overview, dynamic forces modeling, cruise and approach or-bit determination results, and the international teaming arrangement. Significant discussion is dedicated to the events surrounding recovery from the unsuccessful Venus orbit insertion maneuver.

  15. For Earth into space: The German Spacelab Mission D-2 (United States)

    Sahm, P. R.; Keller, M. H.; Schiewe, B.

    The Spacelab Mission D-2 successfully lifted off from Kennedy Space Center on April 26, 1993. With 88 experiments on board covering eleven different research disciplines it was a very ambitious mission. Besides materials and life science subjects, the mission also encompassed astronomy, earth observation, radiation physics and biology, telecommunication, automation and robotics. Notable results were obtained in almost all cases. To give some examples of the scientific output, building upon results obtained in previous missions (FSLP, D1) diffusion in melts was broadly represented delivering most precise data on the atomic mobility within various liquids, and crystal growth experiments (the largest gallium arsenide crystal grown by the floating zone technique, so far obtained anywhere, was one of the results), biological cell growth experiments were continued (for example, beer yeast cultures, continuing their growth on earth, delivered a qualitatively superior brewery result), the human physiology miniclinic configuration ANTHRORACK gave novel insights concerning cardiovascular, pulmonary, and renal (fluid volume determining) factors. Astronomical experiments yielded insights into our own galaxy within the ultra violet spectrum, earth observation experiments delivered the most precise resolution data superimposed by thematic mapping of many areas of the Earth, and the robotics experiment brought a remarkable feature in that a flying object was caught by the space robot, which was only achieved through several innovative advances during the time of experiment preparation. The eight years of preparation were also beneficial in another sense. Several discoveries have been made, and various technology transfers into ground-based processes were verified. To name the outstanding ones, in the materials science a novel bearing materials production process was developped, a patent granted for an improved high temperature heating chamber; with life sciences a new hormone

  16. Missions to Near-Earth Asteroids: Implications for Exploration, Science, Resource Utilization, and Planetary Defense (United States)

    Abell, P. A.; Sanders, G. B.; Mazanek, D. D.; Barbee, B. W.; Mink, R. G.; Landis, R. R.; Adamo, D. R.; Johnson, L. N.; Yeomans, D. K.; Reeves, D. M.; Drake, B. G.; Friedensen, V. P.


    Introduction: In 2009 the Augustine Commission identified near-Earth asteroids (NEAs) as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. More recently the U.S. presidential administration directed NASA to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. NEA Space-Based Survey and Robotic Precursor Missions: The most suitable targets for human missions are NEAs in Earth-like orbits with long synodic periods. However, these mission candidates are often not observable from Earth until the timeframe of their most favorable human mission opportunities, which does not provide an appropriate amount of time for mission development. A space-based survey telescope could more efficiently find these targets in a timely, affordable manner. Such a system is not only able to discover new objects, but also track and characterize objects of interest for human space flight consideration. Those objects with characteristic signatures representative of volatile-rich or metallic materials will be considered as top candidates for further investigation due to their potential for resource utilization and scientific discovery. Once suitable candidates have been identified, precursor spacecraft are required to perform basic reconnaissance of a few NEAs under consideration for the human-led mission. Robotic spacecraft will assess targets for potential hazards that may pose a risk to the deep space transportation vehicle, its deployable assets, and the crew. Additionally, the information obtained about the NEA's basic physical characteristics will be crucial for planning operational activities, designing in-depth scientific/engineering investigations, and identifying sites on the NEA for sample collection. Human Exploration

  17. Space Shuttle orbit determination using empirical force modeling of attitude maneuvers for the German MOMS-02/D2 mission (United States)

    Vonbraun, C.; Reigber, Christoph


    In the spring of 1993, the MOMS-02 (modular Optoelectronic Multispectral Scanner) camera, as part of the second German Spacelab mission aboard STS-55, successfully took digital threefold stereo images of the surface of the Earth. While the mission is experimental in nature, its primary goals are to produce high quality maps and three-dimensional digital terrain models of the Earth's surface. Considerable improvement in the quality of the terrain model can be attained if information about the position and attitude of the camera is included during the adjustment of the image data. One of the primary sources of error in the Shuttle's position is due to the significant attitude maneuvers conducted during the course of the mission. Various arcs, using actual Tracking and Data Relay Satellite (TDRSS) Doppler data of STS-55, were processed to determine how effectively empirical force modeling could be used to solve for the radial, transverse, and normal components of the orbit perturbations caused by these routine maneuvers. Results are presented in terms of overlap-orbit differences in the three components. Comparisons of these differences, before and after the maneuvers are estimated, show that the quality of an orbit can be greatly enhanced with this technique, even if several maneuvers are present. Finally, a discussion is made of some of the difficulties encountered with this approach, and some ideas for future studies are presented.

  18. Enhancing the kinematic precise orbit determination of low earth orbiters using GPS receiver clock modelling (United States)

    Yang, Yang; Yue, Xiaokui; Yuan, Jianping; Rizos, Chris


    Clock error estimation has been the focus of a great deal of research because of the extensive usage of clocks in GPS positioning applications. The receiver clock error in the spacecraft orbit determination is commonly estimated on an epoch-by-epoch basis, along with the spacecraft’s position. However, due to the high correlation between the spacecraft orbit altitude and the receiver clock parameters, estimates of the radial component are degraded in the kinematic approach. Using clocks with high stability, the predictable behaviour of the receiver oscillator can be exploited to improve the positioning accuracy, especially for the radial component. This paper introduces two GPS receiver clock models to describe the deterministic and stochastic property of the receiver clock, both of which can improve the accuracy of kinematic orbit determination for spacecraft in low earth orbit. In particular, the clock parameters are estimated as time offset and frequency offset in the two-state model. The frequency drift is also estimated as an unknown parameter in the three-state model. Additionally, residual non-deterministic random errors such as frequency white noise, frequency random walk noise and frequency random run noise are modelled. Test results indicate that the positioning accuracy could be improved significantly using one day of GRACE flight data. In particular, the error of the radial component was reduced by over 40.0% in the real-time scenario.

  19. Trapped Proton Environment in Medium-Earth Orbit (2000-2010)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yue [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Friedel, Reinhard Hans [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kippen, Richard Marc [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    This report describes the method used to derive fluxes of the trapped proton belt along the GPS orbit (i.e., a Medium-Earth Orbit) during 2000 – 2010, a period almost covering a solar cycle. This method utilizes a newly developed empirical proton radiation-belt model, with the model output scaled by GPS in-situ measurements, to generate proton fluxes that cover a wide range of energies (50keV- 6MeV) and keep temporal features as well. The new proton radiation-belt model is developed based upon CEPPAD proton measurements from the Polar mission (1996 – 2007). Comparing to the de-facto standard empirical model of AP8, this model is not only based upon a new data set representative of the proton belt during the same period covered by GPS, but can also provide statistical information of flux values such as worst cases and occurrence percentiles instead of solely the mean values. The comparison shows quite different results from the two models and suggests that the commonly accepted error factor of 2 on the AP8 flux output over-simplifies and thus underestimates variations of the proton belt. Output fluxes from this new model along the GPS orbit are further scaled by the ns41 in-situ data so as to reflect the dynamic nature of protons in the outer radiation belt at geomagnetically active times. Derived daily proton fluxes along the GPS ns41 orbit, whose data files are delivered along with this report, are depicted to illustrate the trapped proton environment in the Medium-Earth Orbit. Uncertainties on those daily proton fluxes from two sources are evaluated: One is from the new proton-belt model that has error factors < ~3; the other is from the in-situ measurements and the error factors could be ~ 5.

  20. EOS Aura Mission Status at Earth Science Constellation MOWG Meeting @ LASP (Boulder, CO) April 13, 2016 (United States)

    Guit, William J.; Fisher, Dominic


    Presentation reflects EOS Aura mission status, spacecraft subsystems summary, recent and planned activities, inclination adjust maneuvers, propellant usage, orbit maintenance maneuvers, conjunction assessment events, orbital parameters trends and predictions.

  1. Mission to Planet Earth Strategic Enterprise Plan 1996-2002 (United States)


    Mission to Planet Earth's (MTPE's) first Strategic Enterprise Plan, issued in May 1995, defined the Agency's major goals and objectives as well as constraints. This update of the Strategic Enterprise Plan identifies the following major changes: a focused Science Research Plan that integrates space-based and in situ observational critical science to address critical science uncertainties; a technology infusion plan to reduce the cost of future missions; a series of flight opportunities to infuse new science into the overall program; and a tighter coupling between NASA and NOAA to reduce costs and to improve the overall program. Three important new initiatives are also under development and are described briefly in this plan: MTPE Education Strategy, MTPE Commercial Strategy, and an emerging concept for an Integrated Global Observing Strategy. This first update to the MTPE Strategic Enterprise Plan captures these new developments, and takes a significant step forward in planning this complex Earth system science endeavor. The plan and other information on MTPE may be viewed via the Internet at

  2. Mission to Planet Earth. Strategic enterprise plan, 1995-2000 (United States)


    Mission to Planet Earth (MTPE) provides long-term understanding of the earth system needed to protect and improve our environment, now and for future generations. This MTPE Strategic Enterprise Plan states how NASA intends to meet its responsibility to the Nation for developing a long-term, integrated program of environmental observation in support of informed decision-making. This plan implements the NASA Strategic Plan for the MTPE Enterprise; it is the first version of a rolling 5-year plan that will be updated annually. It is consistent with the interagency program developed by the Committee on Environment and Natural Resources of the National Science and Technology Council and implemented in large part through the U.S. Global Change Research Program. This report consists of the following sections: (1) introduction; (2) scientific foundation; (3) mission (destination and purposes); (4) principle of operation (ethical and quality assurance standards); (5) customer base (to ensure that the right products and services are delivered); (6) internal and external assessments; (7) assumptions; (8) goals, objectives, and strategies; (9) linkages to other strategic enterprises; and (10) summary.

  3. Mission to Planet Earth. Strategic enterprise plan, 1995-2000 (United States)


    Mission to Planet Earth (MTPE) provides long-term understanding of the earth system needed to protect and improve our environment, now and for future generations. This MTPE Strategic Enterprise Plan states how NASA intends to meet its responsibility to the Nation for developing a long-term, integrated program of environmental observation in support of informed decision-making. This plan implements the NASA Strategic Plan for the MTPE Enterprise; it is the first version of a rolling 5-year plan that will be updated annually. It is consistent with the interagency program developed by the Committee on Environment and Natural Resources of the National Science and Technology Council and implemented in large part through the U.S. Global Change Research Program. This report consists of the following sections: (1) introduction; (2) scientific foundation; (3) mission (destination and purposes); (4) principle of operation (ethical and quality assurance standards); (5) customer base (to ensure that the right products and services are delivered); (6) internal and external assessments; (7) assumptions; (8) goals, objectives, and strategies; (9) linkages to other strategic enterprises; and (10) summary.

  4. Reducing Earth Topography Resolution for SMAP Mission Ground Tracks Using K-Means Clustering (United States)

    Rizvi, Farheen


    The K-means clustering algorithm is used to reduce Earth topography resolution for the SMAP mission ground tracks. As SMAP propagates in orbit, knowledge of the radar antenna footprints on Earth is required for the antenna misalignment calibration. Each antenna footprint contains a latitude and longitude location pair on the Earth surface. There are 400 pairs in one data set for the calibration model. It is computationally expensive to calculate corresponding Earth elevation for these data pairs. Thus, the antenna footprint resolution is reduced. Similar topographical data pairs are grouped together with the K-means clustering algorithm. The resolution is reduced to the mean of each topographical cluster called the cluster centroid. The corresponding Earth elevation for each cluster centroid is assigned to the entire group. Results show that 400 data points are reduced to 60 while still maintaining algorithm performance and computational efficiency. In this work, sensitivity analysis is also performed to show a trade-off between algorithm performance versus computational efficiency as the number of cluster centroids and algorithm iterations are increased.

  5. Degradation of Spacesuit Fabrics in Low Earth Orbit (United States)

    Gaier, James R.; Baldwin, Sammantha M.; Folz, Angela D.; Waters, Deborah L.; McCue, Terry R.; Jaworske, Donald A.; Clark, Gregory W.; Rogers, Kerry J.; Batman, Brittany; Bruce, John; hide


    Six samples of pristine and dust-abraded outer layer spacesuit fabrics were included in the Materials International Space Station Experiment-7, in which they were exposed to the wake-side low Earth orbit environment on the International Space Station (ISS) for 18 months in order to determine whether abrasion by lunar dust increases radiation degradation. The fabric samples were characterized using optical microscopy, optical spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and tensile testing before and after exposure on the ISS. Comparison of pre- and post-flight characterizations showed that the environment darkened and reddened all six fabrics, increasing their integrated solar absorptance by 7 to 38 percent. There was a decrease in the ultimate tensile strength and elongation to failure of lunar dust abraded Apollo spacesuit fibers by a factor of four and an increase in the elastic modulus by a factor of two.

  6. Optimization of Return Trajectories for Orbital Transfer Vehicle between Earth and Moon (United States)

    Funase, Ryu; Tsuda, Yuichi; Kawaguchi, Jun'ichiro


    In this paper, optimum trajectories in Earth Transfer Orbit (ETO) for a lunar transportation system are proposed. This paper aims at improving the payload ratio of the reusable orbital transfer vehicle (OTV), which transports the payload from Low Earth Orbit (LEO) to Lunar Low Orbit (LLO) and returns to LEO. In ETO, we discuss ballistic flight using chemical propulsion, multi-impulse flight using electrical propulsion, and aero-assisted flight using aero-brake. The feasibility of the OTV is considered.

  7. Orbit-Attitude Changes of Objects in Near Earth Space Induced by Natural Charging (United States)


    Propagation; Magnetic Field; Geosynchronous Orbit ; Satellite Components; Electrons; Operational Anomalies 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...charging in the near geosynchronous orbit have been done. DeForest [4] investigated charging of ATS-5 satellite in geosynchronous orbit . He found that...common, high-level charging can also be experienced in low Earth orbit . Defense Meteorological Satellite Program (DMSP) spacecraft in low Earth polar

  8. Three-Dimensional Orbits of Earth Satellites, Including Effects of Earth Oblateness and Atmospheric Rotation (United States)

    Nielsen, Jack N.; Goodwin, Frederick K.; Mersman, William A.


    The principal purpose of the present paper is to present sets of equations which may be used for calculating complete trajectories of earth satellites from outer space to the ground under the influence of air drag and gravity, including oblateness effects, and to apply these to several examples of entry trajectories starting from a circular orbit. Equations of motion, based on an "instantaneous ellipse" technique, with polar angle as independent variable, were found suitable for automatic computation of orbits in which the trajectory consists of a number of revolutions. This method is suitable as long as the trajectory does not become nearly vertical. In the terminal phase of the trajectories, which are nearly vertical, equations of motion in spherical polar coordinates with time as the independent variable were found to be more suitable. In the first illustrative example the effects of the oblateness component of the earth's gravitational field and of atmospheric rotation were studied for equatorial orbits. The satellites were launched into circular orbits at a height of 120 miles, an altitude sufficiently high that a number of revolutions could be studied. The importance of the oblateness component of the earth's gravitational field is shown by the fact that a satellite launched at circular orbital speed, neglecting oblateness, has a perigee some 67,000 feet lower when oblateness forces are included in the equations of motion than when they are not included. Also, the loss in altitude per revolution is double that of a satellite following an orbit not subject to oblateness. The effect of atmospheric rotation on the loss of altitude per revolution was small. As might be surmised, the regression of the line of nodes as predicted by celestial mechanics is unchanged when drag is included. It is clear that the inclination of the orbital plane to the equator will be relatively unaffected by drag for no atmospheric rotation since the drag lies in the orbital plane in

  9. Controllable ON-OFF adhesion for Earth orbit grappling applications (United States)

    Parness, Aaron; Hilgendorf, Tyler; Daniel, Phillip; Frost, Matt; White, Victor; Kennedy, Brett

    ON-OFF adhesives can benefit multiple Earth orbit applications by providing the capability to selectively anchor two surfaces together repeatedly and releasably without significant preload. Key to this new capability, targets will not need special preparation; ON-OFF adhesives can be used with cooperative and non-cooperative objects, like defunct satellites or space debris. Using an ON-OFF adhesive gripper allows large surfaces on a target to serve as potential grapple points, reducing the precision needed in the sensing and control throughout the grapple operation. A space-rated adhesive structure is presented that can be turned ON-OFF using a slight sliding motion. This adhesive mimics the geometry and performance characteristics of the adhesive structures found on the feet of gecko lizards. Results from adhesive testing on common orbital surfaces like solar panels, thermal blankets, composites, and painted surfaces are presented. Early environmental testing results from cold temperature and vacuum tests are also presented. Finally, the paper presents the design, fabrication, and preliminary testing of a gripping mechanism enabled by these ON-OFF adhesives in preparation for satellite-servicing applications. Adhesive levels range from near zero on rough surfaces to more than 75 kPa on smooth surfaces like glass.

  10. The BIOMASS mission — An ESA Earth Explorer candidate to measure the BIOMASS of the earth's forests

    DEFF Research Database (Denmark)

    Scipal, K.; Arcioni, M.; Chave, J.


    The European Space Agency (ESA) released a Call for Proposals for the next Earth Explorer Core Mission in March 2005, with the aim to select the 7th Earth Explorer (EE-7) mission for launch in the next decade. Twenty-four proposals were received and subject to scientific and technical assessment...

  11. Mission Report on the Orbiter Camera Payload System (OCPS) Large Format Camera (LFC) and Attitude Reference System (ARS) (United States)

    Mollberg, Bernard H.; Schardt, Bruton B.


    The Orbiter Camera Payload System (OCPS) is an integrated photographic system which is carried into earth orbit as a payload in the Space Transportation System (STS) Orbiter vehicle's cargo bay. The major component of the OCPS is a Large Format Camera (LFC), a precision wide-angle cartographic instrument that is capable of producing high resolution stereo photography of great geometric fidelity in multiple base-to-height (B/H) ratios. A secondary, supporting system to the LFC is the Attitude Reference System (ARS), which is a dual lens Stellar Camera Array (SCA) and camera support structure. The SCA is a 70-mm film system which is rigidly mounted to the LFC lens support structure and which, through the simultaneous acquisition of two star fields with each earth-viewing LFC frame, makes it possible to determine precisely the pointing of the LFC optical axis with reference to the earth nadir point. Other components complete the current OCPS configuration as a high precision cartographic data acquisition system. The primary design objective for the OCPS was to maximize system performance characteristics while maintaining a high level of reliability compatible with Shuttle launch conditions and the on-orbit environment. The full-up OCPS configuration was launched on a highly successful maiden voyage aboard the STS Orbiter vehicle Challenger on October 5, 1984, as a major payload aboard mission STS 41-G. This report documents the system design, the ground testing, the flight configuration, and an analysis of the results obtained during the Challenger mission STS 41-G.

  12. MarcoPolo-R: Near Earth Asteroid Sample Return Mission candidate as ESA-M3 class mission (United States)

    Michel, Patrick; Lara, Luisa-M.; Marty, Bernard; Koschny, Detlef; Barucci, Maria Antonietta; Cheng, Andy; Bohnhardt, Hermann; Brucato, John R.; Dotto, Elisabetta; Ehrenfreund, Pascale; Franchi, Ian A.; Green, Simon F.


    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) selected in February 2011 for the Assessment Study Phase at ESA in the framework of ESAfs Cosmic Vision 2 program. MarcoPolo-R is a European-led mission with a proposed NASA contribution. MarcoPolo-R takes advantage of three industrial studies completed as part of the previous Marco Polo mission (see ESA/SRE (2009)3). The aim of the new Assessment Study is to reduce the cost of the mission while maintaining its high science level, on the basis of advanced studies and technologies, as well as optimization of the mission. MarcoPolo-R will rendezvous with a unique kind of target, a primitive binary NEA, scientifically characterize it at multiple scales, and return a unique pristine sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. The baseline target of MarcoPolo-R is the primitive binary NEA (175706) 1996 FG3, which offers a very efficient operational and technical mission profile. A binary target also provides enhanced science return: the choice of this target will allow new investigations to be performed more easily compared to a single object, and also enables investigations of the fascinating geology and geophysics of asteroids that are impossible to obtain from a single object. Precise measurements of the mutual orbit and rotation state of both components can be used to probe higher-level harmonics of the gravitational potential, and therefore the internal structure. A unique opportunity is offered to study the dynamical evolution driven by the YORP/Yarkovsky thermal effects. Possible migration of regolith on the primary from poles to equator allows the increasing maturity of asteroidal regolith with time to be expressed as a latitude-dependent trend, with the most-weathered material at the equator matching what is seen in the secondary. MarcoPolo-R will allow us to study the most primitive materials available to investigate early solar system

  13. Mission Status for Earth Science Constellation MOWG Meeting at KSC: EOS Aura (United States)

    Fisher, Dominic


    This will be presented at the Earth Science Constellation Mission Operations Working Group (MOWG) meeting at KSC (Kennedy Space Center) in December 2017 to discus EOS (Earth Observing System) Aura status. Reviewed and approved by Eric Moyer, ESMO (Earth Sciences Mission Operations) Deputy Project Manager.

  14. Alterations in the heart rate and activity rhythms of three orbital astronauts on a space mission. (United States)

    Liu, Zhizhen; Wan, Yufeng; Zhang, Lin; Tian, Yu; Lv, Ke; Li, Yinghui; Wang, Chunhui; Chen, Xiaoping; Chen, Shanguang; Guo, Jinhu


    Environmental factors in space are dramatically different from those on Earth. The spaceflight environment has been known to influence human physiology and behavior on orbital missions. In this study, we investigated alterations in the diurnal rhythms of activity and heart rate of three Chinese astronauts on a space mission. An analysis of the heart rate data showed a significant decrease in heart rate amplitudes during flight in all three subjects. The heart rate amplitudes of all the three astronauts were significantly dampened during flight, and the minimum as well as the maximum value of heart rate increased after flight. A phase shift in heart rate was observed in one of the three astronauts after flight. These results demonstrate the influence of spaceflight on heart physiology and function. In addition, a significant decrease in body trunk activity and rhythmicity occurred during flight, demonstrating that the spaceflight environment disturbs motion adaptation and diurnal activity rhythms. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  15. S ynergies With The Solar Orbiter Mission: Remote Sensing Studies Of The Corona And Coronal Transients (United States)

    Vourlidas, A.


    Currently, the Solar Orbiter (SolO) mission is planned to start its science observations around the next solar minimum (2018-2020) and extend to the maximum of cycle 25. Given the demanding deep space orbit and the restrictions on spacecraft resources, the mission will likely include a modest instrument payload designed to fully address a focused set of solar physics problems. Hopefully, SolO will not be the only solar mission op- erating at the time. The scientific return of the SolO mission will be greatly enhanced by joint observational programs with other instruments, both space-borne and gound- based ones. In this paper, I concentrate on obser- vations of the outer corona and of coronal mass ejections and discuss a few examples of synergistic science at the time of the SolO mission with an emphasis on the unique characteristics of the SolO orbit.

  16. Trajectories and orbital maneuvers for the ISEE-3/ICE comet mission (United States)

    Farquhar, R.; Muhonen, D.; Church, L. C.


    The ISEE-3/ICE spacecraft, (launched in 1978), and expected to obtain the first measurements of comet Giacobinni-Zinner in September 1985, has undertaken a combination of propulsive maneuvers, lunar swing-bys, and solar perturbations to produce its present trajectory profile. ISEE-3 is a drum-shaped, spin-stabilized spacecraft equipped with a redundant pair of high-resolution sun sensors, a medium-gain S-band antenna, a hydrazine propulsion system and a science experiment payload. After being placed into a sun-earth libration halo orbit in late 1978, ISEE-3 was retargeted to the geomagnetotail in mid-1982 and became the first spacecraft to explore the geomagnetic tail between 80 and 237 earth radii in 1983. These types of maneuvers may prove important for future scientific missions planned as follow-ons to ISEE-3/ICE, such as a joint NASA/ISAS project spacecraft scheduled for Shuttle launch in 1991, and a possible encounter with two comets in 1996 anad 1998.

  17. Advantage of Animal Models with Metabolic Flexibility for Space Research Beyond Low Earth Orbit (United States)

    Griko, Yuri V.; Rask, Jon C.; Raychev, Raycho


    As the world's space agencies and commercial entities continue to expand beyond Low Earth Orbit (LEO), novel approaches to carry out biomedical experiments with animals are required to address the challenge of adaptation to space flight and new planetary environments. The extended time and distance of space travel along with reduced involvement of Earth-based mission support increases the cumulative impact of the risks encountered in space. To respond to these challenges, it becomes increasingly important to develop the capability to manage an organism's self-regulatory control system, which would enable survival in extraterrestrial environments. To significantly reduce the risk to animals on future long duration space missions, we propose the use of metabolically flexible animal models as "pathfinders," which are capable of tolerating the environmental extremes exhibited in spaceflight, including altered gravity, exposure to space radiation, chemically reactive planetary environments and temperature extremes. In this report we survey several of the pivotal metabolic flexibility studies and discuss the importance of utilizing animal models with metabolic flexibility with particular attention given to the ability to suppress the organism's metabolism in spaceflight experiments beyond LEO. The presented analysis demonstrates the adjuvant benefits of these factors to minimize damage caused by exposure to spaceflight and extreme planetary environments. Examples of microorganisms and animal models with dormancy capabilities suitable for space research are considered in the context of their survivability under hostile or deadly environments outside of Earth. Potential steps toward implementation of metabolic control technology in spaceflight architecture and its benefits for animal experiments and manned space exploration missions are discussed.

  18. Orbital trim by velocity factoring with applications to the Viking mission. (United States)

    Kibler, J. F.; Green, R. N.; Young, G. R.


    An orbital trim technique has been developed to satisfy terminal rendezvous and intermediate timing constraints for planetary missions involving orbital operations. The technique utilizes a time-open two-impulse transfer from a specified initial orbit to a final orbit which satisfies all geometrical constraints. Each of the two impulses may then be factored, or split, into two or more vectorially equivalent impulses. The periods of the resulting intermediate orbits may be varied along with the number of revolutions in each orbit to satisfy the intermediate and final timing constraints. Factors in the range 0 to 1 result in rendezvous at the same cost as that of the two-impulse transfer. The technique is applied to the Viking mission to Mars although a similar procedure could be utilized for rendezvous operations about any planet.

  19. TWINKLE - A Low Earth Orbit Visible and Infrared Exoplanet Spectroscopy Observatory (United States)

    Tessenyi, M.; Savini, G.; Tinetti, G.; Tennyson, J.; Dhesi, M.; Joshua, M.


    Twinkle is a space mission designed for visible and near-IR spectroscopic observations of extrasolar planets. Twinkle's highly stable instrument will allow the photometric and spectroscopic observation of a wide range of planetary classes around different types of stars, with a focus on bright sources close to the ecliptic. The planets will be observed through transit and eclipse photometry and spectroscopy, as well as phase curves, eclipse mapping and multiple narrow-band time-series. The targets observed by Twinkle will be composed of known exoplanets mainly discovered by existing and upcoming ground surveys in our galaxy and will also feature new discoveries by space observatories (K2, GAIA, Cheops, TESS). Twinkle is a small satellite with a payload designed to perform high-quality astrophysical observations while adapting to the design of an existing Low Earth Orbit commercial satellite platform. The SSTL-300 bus, to be launched into a low-Earth sun-synchronous polar orbit by 2019, will carry a half-meter class telescope with two instruments (visible and near-IR spectrographs - between 0.4 and 4.5μm - with resolving power R˜300 at the lower end of the wavelength scale) using mostly flight proven spacecraft systems designed by Surrey Satellite Technology Ltd and a combination of high TRL instrumentation and a few lower TRL elements built by a consortium of UK institutes. The Twinkle design will enable the observation of the chemical composition and weather of at least 100 exoplanets in the Milky Way, including super-Earths (rocky planets 1-10 times the mass of Earth), Neptunes, sub-Neptunes and gas giants like Jupiter. It will also allow the follow-up photometric observations of 1000+ exoplanets in the visible and infrared, as well as observations of Solar system objects, bright stars and disks.

  20. Non-numeric computation for high eccentricity orbits. [Earth satellite orbit perturbation (United States)

    Sridharan, R.; Renard, M. L.


    Geocentric orbits of large eccentricity (e = 0.9 to 0.95) are significantly perturbed in cislunar space by the sun and moon. The time-history of the height of perigee, subsequent to launch, is particularly critical. The determination of 'launch windows' is mostly concerned with preventing the height of perigee from falling below its low initial value before the mission lifetime has elapsed. Between the extremes of high accuracy digital integration of the equations of motion and of using an approximate, but very fast, stability criteria method, this paper is concerned with the developement of a method of intermediate complexity using non-numeric computation. The computer is used as the theory generator to generalize Lidov's theory using six osculating elements. Symbolic integration is completely automatized and the output is a set of condensed formulae well suited for repeated applications in launch window analysis. Examples of applications are given.

  1. MESSENGER, MErcury: Surface, Space ENvironment, GEochemistry, and Ranging; A Mission to Orbit and Explore the Planet Mercury (United States)


    MESSENGER is a scientific mission to Mercury. Understanding this extraordinary planet and the forces that have shaped it is fundamental to understanding the processes that have governed the formation, evolution, and dynamics of the terrestrial planets. MESSENGER is a MErcury Surface, Space ENvironment, GEochemistry and Ranging mission to orbit Mercury for one Earth year after completing two flybys of that planet following two flybys of Venus. The necessary flybys return significant new data early in the mission, while the orbital phase, guided by the flyby data, enables a focused scientific investigation of this least-studied terrestrial planet. Answers to key questions about Mercury's high density, crustal composition and structure, volcanic history, core structure, magnetic field generation, polar deposits, exosphere, overall volatile inventory, and magnetosphere are provided by an optimized set of miniaturized space instruments. Our goal is to gain new insight into the formation and evolution of the solar system, including Earth. By traveling to the inner edge of the solar system and exploring a poorly known world, MESSENGER fulfills this quest.

  2. Probable Rotation States of Rocket Bodies in Low Earth Orbit (United States)

    Ojakangas, Gregory W.; Anz-Meador, P.; Cowardin, H.


    In order for Active Debris Removal to be accomplished, it is critically important to understand the probable rotation states of orbiting, spent rocket bodies. As compared to the question of characterizing small unresolved debris, in this problem there are several advantages: (1) objects are of known size, mass, shape and color, (2) they have typically been in orbit for a known period of time, (3) they are large enough that resolved images may be obtainable for verification of predicted orientation, and (4) the dynamical problem is simplified to first order by largely cylindrical symmetry. It is also nearly certain for realistic rocket bodies that internal friction is appreciable in the case where residual liquid or, to a lesser degree, unconsolidated solid fuels exist. Equations of motion have been developed for this problem in which internal friction as well as torques due to solar radiation, magnetic induction, and gravitational gradient are included. In the case of pure cylindrical symmetry, the results are compared to analytical predictions patterned after the standard approach for analysis of symmetrical tops. This is possible because solar radiation and gravitational torques may be treated as conservative. Agreement between results of both methods ensures their mutual validity. For monotone symmetric cylinders, solar radiation torque vanishes if the center of mass resides at the geometric center of the object. Results indicate that in the absence of solar radiation effects, rotation states tend toward an equilibrium configuration in which rotation is about the axis of maximum inertia, with the axis of minimum inertia directed toward the center of the earth. Solar radiation torque introduces a modification to this orientation. The equilibrium state is asymptotically approached within a characteristic timescale given by a simple ratio of relevant characterizing parameters for the body in question. Light curves are simulated for the expected asymptotic final

  3. Changes in the Optical Properties of Materials Are Observed After 18 Months in Low Earth Orbit (United States)

    Jaworske, Donald A.


    Materials located on the exterior of spacecraft in low Earth orbit are subjected to a number of environmental threats, including atomic oxygen, ultraviolet radiation, thermal cycling, and micrometeroid and debris impact. Atomic oxygen attacks materials vulnerable to oxidation. Ultraviolet radiation can break chemical bonds and cause undesirable changes in optical properties. Thermal cycling can cause cracking, and micrometeroid and debris impacts can damage protective coatings. Another threat is contamination. The outgassing of volatile chemicals can contaminate nearby surfaces, changing their thermal control properties. Contaminated surfaces may undergo further change as a result of atomic oxygen and ultraviolet radiation exposure. The Passive Optical Sample Assembly (POSA) experiment was designed as a risk mitigation experiment for the International Space Station. Samples were characterized before launch, exposed for 18 months on the exterior of Mir, and characterized upon their return. Lessons learned from POSA about the durability of material properties can be applied to the space station and other long-duration missions.

  4. Investigation of Teflon FEP Embrittlement on Spacecraft in Low-Earth Orbit (United States)

    deGroh, Kim K.; Banks, Bruce A.


    Teflon fluorinated ethylene propylene (FEP) (DuPont) is commonly used on exterior spacecraft surfaces for thermal control in the low-Earth orbit environment. Silverized or aluminized Teflon FEP is used for the outer layers of the thermal control blanket because of its high reflectance, low solar absorptance, and high thermal emittance. Teflon FEP is also desirable because, compared with other spacecraft polymers (such as Kapton), it has relatively high resistance to atomic oxygen erosion. Because of its comparably low atomic oxygen erosion yield, Teflon FEP has been used unprotected in the space environment. Samples of Teflon FEP from the Long Duration Exposure Facility (LDEF) and the Hubble Space Telescope (retrieved during its first servicing mission) were evaluated for solar-induced embrittlement and for synergistic effects of solar degradation and atomic oxygen.

  5. Preparations for Lunar Reconnaissance Orbiter gravity and altimetry missions (United States)

    Mazarico, E.; Lemoine, F. G.; Neumann, G. A.; Smith, D. E.; Rowlands, D. D.; Zuber, M. T.


    The launch of the Lunar Reconnaissance Orbiter is expected in early 2009. We present results of the preparations undertaken at the NASA Goddard Space Flight Center for the Lunar Orbiter Laser Altimeter (LOLA) instrument and the Radio Science experiment. A new lunar reference frame, vital to current exploration efforts for a return to the Moon, will be developed from the combined data sets collected by both experiments. In addition to collecting topographic data, LOLA will assist the Precision Orbit Determination of the LRO spacecraft. The 50-m total positioning requirement is very challenging due to the low altitude (50km on average) and the lack of radio tracking over most of the lunar far side. While commercial S-band tracking data will be the principal measurements used for orbit reconstruction, the unique five-beam altimeter enables the use of the altimetric cross-over technique with unprecedented accuracy. Previous simulations showed that the more numerous (by a factor of 25) crossings could greatly help in reducing the uncertainties in the recovered orbit. We show here that cross-track information contained in the acquired topographic swaths (compared to multiple two-dimensional profiles) can constrain orbits to a few meters horizontally and better than 50cm vertically. Swath cross-overs will be most valuable in mid-latitudes, where cross-overs are sparse and tracks intersect at shallow angles. A spacecraft physical model, for use in the GEODYN II orbit determination program, includes inter-plate self- shadowing in the calculation of the spacecraft cross-sectional area for solar radiation pressure. Simulations indicate that solar radiation effects on the orbit can be on the order of 10-20m. Because the thermal radiation forces are larger and more variable than on Mars, the current model of the thermal flux map was updated, with effects on the order of 1-5m. The benefit of using the self-shadowing model for the albedo and thermal forces is currently being

  6. Laboratory investigations: Low Earth orbit environment chemistry with spacecraft surfaces (United States)

    Cross, Jon B.


    Long-term space operations that require exposure of material to the low earth orbit (LEO) environment must take into account the effects of this highly oxidative atmosphere on material properties and the possible contamination of the spacecraft surroundings. Ground-based laboratory experiments at Los Alamos using a newly developed hyperthermal atomic oxygen (AO) source have shown that not only are hydrocarbon based materials effected but that inorganic materials such as MoS2 are also oxidized and that thin protective coatings such as Al2O3 can be breached, producing oxidation of the underlying substrate material. Gas-phase reaction products, such as SO2 from oxidation of MoS2 and CO and CO2 from hydrocarbon materials, have been detected and have consequences in terms of spacecraft contamination. Energy loss through gas-surface collisions causing spacecraft drag has been measured for a few select surfaces and has been found to be highly dependent on the surface reactivity.

  7. An Assessment of Relativistic Effects for Low Earth Orbiters: The GRACE Satellites (United States)


    IOP PUBLISHING METROLOGIA Metrologia 44 (2007) 484–490 doi:10.1088/0026-1394/44/6/007 An assessment of relativistic effects for low Earth orbiters...for the larger-eccentricity orbit is shown in figure 2(b). Metrologia , 44 (2007) 484–490 485 K M Larson et al Figure 1. Amplitude of the once/rev...486 Metrologia , 44 (2007) 484–490 Assessment of relativistic effects for low Earth orbiters combination was launched on TOPEX in 1992. Unfortunately

  8. Frozen orbits for satellites close to an earth-like planet (United States)

    Coffey, Shannon L.; Deprit, Andre; Deprit, Etienne


    We say that a planet is Earth-like if the coefficient of the second order zonal harmonic dominates all other coefficients in the gravity field. This paper concerns the zonal problem for satellites around an Earth-like planet, all other perturbations excluded. The potential contains all zonal coefficients J2 through J9. The model problem is averaged over the mean anomaly by a Lie transformation to the second order; we produce the resulting Hamiltonian as a Fourier series in the argument of perigee whose coefficients are algebraic functions of the eccentricity - not truncated power series. We then proceed to a global exploration of the equilibria in the averaged problem. These singularities which aerospace engineers know by the name of frozen orbits are located by solving the equilibria equations in two ways, (1) analytically in the neighborhood of either the zero eccentricity or the critical inclination, and (2) numerically by a Newton-Raphson iteration applied to an approximate position read from the color map of the phase flow. The analytical solutions we supply in full to assist space engineers in designing survey missions. We pay special attention to the manner in which additional zonal coefficients affect the evolution of bifurcations we had traced earlier in the main problem (J2 only). In particular, we examine the manner in which the odd zonal J3 breaks the discrete symmetry inherent to the even zonal problem. In the even case, we find that Vinti's problem (J4 + J22 = 0) p resents a degeneracy in the form of non-isolated equilibria; we surmise that the degeneracy is a reflection of the fact that Vinti's problem is separable. By numerical continuation we have discovered three families of frozen orbits in the full zonal problem under consideration; (1) a family of stable equilibria starting from the equatorial plane and tending to the critical inclination; (2) an unstable family arising from the bifurcation at the critical inclination; (3) a stable family also

  9. Near Earth Asteroid Human Mission Possibilities Using Nuclear Thermal Rocket (NTR) Propulsion (United States)

    Borowski, Stanley; McCurdy, David R.; Packard, Thomas W.


    The NTR is a proven technology that generates high thrust and has a specific impulse (Isp (is) approximately 900 s) twice that of today's best chemical rockets. During the Rover and NERVA (Nuclear Engine for Rocket Vehicle Applications) programs, twenty rocket reactors were designed, built and ground tested. These tests demonstrated: (1) a wide range of thrust; (2) high temperature carbide-based nuclear fuel; (3) sustained engine operation; (4) accumulated lifetime; and (5) restart capability - all the requirements needed for a human mission to Mars. Ceramic metal fuel was also evaluated as a backup option. In NASA's recent Mars Design reference Architecture (DRA) 5.0 study, the NTR was selected as the preferred propulsion option because of its proven technology, higher performance, lower launch mass, versatile vehicle design, simple assembly, and growth potential. In contrast to other advanced propulsion options, NTP requires no large technology scale-ups. In fact, the smallest engine tested during the Rover program - the 25 klbf 'Pewee' engine is sufficient for a human Mars mission when used in a clustered engine configuration. The 'Copernicus crewed NTR Mars transfer vehicle design developed for DRA 5.0 has significant capability that can enable reusable '1-year' round trip human missions to candidate near Earth asteroids (NEAs) like 1991 JW in 2027, or 2000 SG344 and Apophis in 2028. A robotic precursor mission to 2000 SG344 in late 2023 could provide an attractive Flight Technology Demonstration of a small NTR engine that is scalable to the 25 klbf-class engine used for human missions 5 years later. In addition to the detailed scientific data gathered from on-site inspection, human NEA missions would also provide a valuable 'check out' function for key elements of the NTR transfer vehicle (its propulsion module, TransHab and life support systems, etc.) in a 'deep space' environment prior to undertaking the longer duration Mars orbital and landing missions that

  10. Software and hardware implements for tracking low earth orbit (LEO) satellites


    Rahal, Wassila Leila; Banabadji, Noureddine; Belbachir, Ahmed Hafid


    International audience; In this paper, we present a novel, precise and efficient tracking system for Low Earth Orbit (LEO) Satellites. We have developed a software (LAAR-Track) and a hardware interface for orbit determination based on using orbital elements, which are given by the NORAD (North American Aerospace Defence). Orbital perturbations, such as the atmospheric drag, the influence of the moon and the sun and the geopotential field have been considered for satellites trajectory determin...

  11. Effects of Low Earth Orbit on Docking Seal Materials (United States)

    Imka, Emily C.; Asmar, Olivia C.; deGroh, Henry C., III; Banks, Bruce A.


    Spacecraft docking seals are typically made of silicone elastomers. When such seals are exposed to low Earth orbit (LEO) conditions, they can suffer damage from ultraviolet (UV) radiation and atomic oxygen (AO, or monoatomic oxygen, the predominant oxygen species in LEO). An experiment flew on the International Space Station (ISS) to measure the effects of LEO on seal materials S0383-70 and ELA-SA-401 and various mating counterface materials which included anodized aluminum. Samples flown in different orientations received different amounts of UV and AO. The hypotheses were that most of the damage would be from UV, and 10 days or more of exposure in LEO would badly damage the seals. Eighteen seals were exposed for 543 days in ram (windward), zenith (away from Earth), or wake (leeward) orientations, and 15 control samples (not flown) provided undamaged baseline leakage. To determine post-flight leak rates, each of the 33 seals were placed in an O-ring groove of a leak test fixture and pressure tested over time. Resistance temperature detectors (RTDs), pressure transducers, and LabVIEW (National Instruments) programs were used to measure and analyze the temperature and pressure and calculate leakage. Average leakage of control samples was 2.6 x 10(exp -7) lbs/day. LEO exposure did not considerably damage ELA-SA-401. The S0383-70 flight samples leaked at least 10 times more than ELA-SA-401 in all cases except one, demonstrating that ELA-SA-401 may be a more suitable sealing material in LEO. AO caused greater damage than UV; samples in ram orientation (receiving an AO fluence of 4.3 x 10(exp 21) atoms/(sq cm) and in wake (2.9x 10(exp 20) atoms/(sq cm)) leaked more than those in zenith orientation (1.58 x 10(exp 20) atoms/(sq cm)), whereas variations in UV exposure did not seem to affect the samples. Exposure to LEO did less damage to the seals than hypothesized, and the data did not support the conjecture that UV causes more damage than AO.

  12. COMPASS Final Report: Radioisotope Electric Propulsion (REP) Centaur Orbiter New Frontiers Mission (United States)

    Oleson, Steven R.; McGuire, Melissa L.


    Radioisotope Electric Propulsion (REP) has been shown in past studies to enable missions to outer planetary bodies including the orbiting of Centaur asteroids. Key to the feasibility for REP missions are long life, low power electric propulsion (EP) devices, low mass Radioisotope Power System (RPS) and light spacecraft (S/C) components. In order to determine the key parameters for EP devices to perform these REP missions a design study was completed to design an REP S/C to orbit a Centaur in a New Frontiers (NF) cost cap. The design shows that an orbiter using several long lived (approx.200 kg xenon (Xe) throughput), low power (approx.700 W) Hall thrusters teamed with six (150 W each) Advanced Stirling Radioisotope Generators (ASRG) can deliver 60 kg of science instruments to a Centaur in 10 yr within the NF cost cap. Optimal specific impulses (Isp) for the Hall thrusters were found to be around 2000 s with thruster efficiencies over 40 percent. Not only can the REP S/C enable orbiting a Centaur (when compared to an all chemical mission only capable of flybys) but the additional power from the REP system can be used to enhance science and simplify communications. The mission design detailed in this report is a Radioisotope Power System (RPS) powered EP science orbiter to the Centaur Thereus with arrival 10 yr after launch, ending in a 1 yr science mapping mission. Along the trajectory, approximately 1.5 yr into the mission, the REP S/C does a flyby of the Trojan asteroid Tlepolemus. The total (Delta)V of the trajectory is 8.9 km/s. The REP S/C is delivered to orbit on an Atlas 551 class launch vehicle with a Star 48 B solid rocket stage

  13. Assessment of the consequences of the Fengyun-1C breakup in low Earth orbit (United States)

    Pardini, Carmen

    On 11 January 2007, the 880 kg (958 kg at launch) weather spacecraft Fengyun-1C, launched on 10 May 1999 into a sun-synchronous orbit with a CZ-4B booster from the Taiyuan Satellite Launch Center, was destroyed over central China as a result of the first successful Chinese anti-satellite weapon test. It was carried out with a direct ascent interception with a kinetic energy kill vehicle launched by an SC-19 missile, fired from a mobile ground platform close to the Xichang Satellite Launch Center. While the technical details of the test, probably the third attempt, and the characteristics of the weapon used remain shrouded in secrecy, the intentional breakup of the aging weather spacecraft, fully functional until 2005, produced a huge amount of debris in one of the orbital regimes already most affected by past fragmentation events. At present, the US Space Surveillance Network has identified about 2600 objects, typically larger than 10 cm, but the fragments larger than 1 cm may be more than 100,000. After two decades of substantial international progress in the field of orbital debris mitigation, in order to preserve the low Earth and geosynchronous environments for future space missions, the Fengyun-1C destruction represented a serious turnabout. In fact, it abruptly increased by approximately 20% the number of cataloged debris in orbit. To give a rough idea of the impact of this single event on the circumterrestrial environment, it is sufficient to realize that about 15 years of global space activity - including failures and accidental breakups - had been needed to increase, by a comparable amount, the number of cataloged debris in orbit to the level observed before the Chinese anti-satellite test. The purpose of this presentation is to assess the impact of the debris cloud generated by the Fengyun-1C breakup on the low Earth environment. The anti-satellite test was carried out at an altitude of about 863 km, spreading the cataloged fragments between 200 and 4000

  14. Mission planning for on-orbit servicing through multiple servicing satellites: A new approach (United States)

    Daneshjou, K.; Mohammadi-Dehabadi, A. A.; Bakhtiari, M.


    In this paper, a novel approach is proposed for the mission planning of on-orbit servicing such as visual inspection, active debris removal and refueling through multiple servicing satellites (SSs). The scheduling has been done with the aim of minimization of fuel consumption and mission duration. So a multi-objective optimization problem is dealt with here which is solved by employing particle swarm optimization algorithm. Also, Taguchi technique is employed for robust design of effective parameters of optimization problem. The day that the SSs have to leave parking orbit, transfer duration from parking orbit to final orbit, transfer duration between one target to another, and time spent for the SS on each target are the decision parameters which are obtained from the optimization problem. The raised idea is that in addition to the aforementioned decision parameters, eccentricity and inclination related to the initial orbit and also phase difference between the SSs on the initial orbit are identified by means of optimization problem, so that the designer has not much role on determining them. Furthermore, it is considered that the SS and the target rendezvous at the servicing point and the SS does not perform any phasing maneuver to reach the target. It should be noted that Lambert theorem is used for determination of the transfer orbit. The results show that the proposed approach reduces the fuel consumption and the mission duration significantly in comparison with the conventional approaches.

  15. Conceptual radiometer design studies for Earth observations from low Earth orbit (United States)

    Harrington, Richard F.


    A conceptual radiometer design study was performed to determine the optimum design approach for spaceborne radiometers in low Earth orbit. Radiometric system configurations which included total power radiometers, unbalanced Dicke radiometers, and balanced Dicke, or as known as noise injection, radiometers were studied. Radiometer receiver configurations which were analyzed included the direct detection radiometer receiver, the double sideband homodyne radiometer receiver, and the single sideband heterodyne radiometer receiver. Radiometer system performance was also studied. This included radiometric sensitivity analysis of the three different radiometer system configurations studied. Both external and internal calibration techniques were analyzed. An accuracy analysis with and without mismatch losses was performed. It was determined that the balanced Dicke radiometer system configuration with direct detection receivers and external calibrations was optimum where frequent calibration such as once per minute were not feasible.

  16. MarcoPolo-R: Near Earth Asteroid Sample Return Mission in ESA assessment study phase (United States)

    Barucci, M. A.; Michel, P.; Cheng, A.; Böhnhardt, H.; Brucato, J. R.; Dotto, E.; Ehrenfreund, P.; Franchi, I. A.; Green, S. F.; Lara, L. M.; Marty, B.; Koschny, D.


    MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) selected in February 2011 for the Assessment Study Phase in the framework of ESA's Cosmic Vision 2 program. MarcoPolo-R is a European-led mission with a proposed NASA contribution. MarcoPolo-R takes advantage of three industrial studies completed as part of the previous Marco Polo mission (see ESA/SRE (2009)3). The aim of the new Assessment Study is to reduce the cost of the mission while maintaining its high science level, on the basis of advanced studies and technologies, optimization of the mission, and consolidation of the collaboration with other partners (NASA, AEB…). The main goal of the MarcoPolo-R mission is to return unaltered NEA material for detailed analysis in ground-based laboratories. The limited sampling provided by meteorites does not offer the most primitive material available in near-Earth space. More primitive material, having experienced less alteration on the asteroid, will be more friable and would not survive atmospheric entry in any discernible amount. Only in Earth laboratories can instruments measure the individual components of the complex mixture of materials that forms an asteroid regolith with the necessary precision and sensitivity to determine their precise chemical and isotopic composition. Such measurements are vital for revealing the evidence of stellar, interstellar medium, pre-solar nebula and parent body processes that are retained in primitive asteroidal material, unaltered by atmospheric entry or terrestrial contamination. It is no surprise therefore that sample return missions are considered a priority by a number of the leading space agencies. MarcoPolo-R will rendezvous with a unique kind of target, a primitive binary NEA, scientifically characterize it at multiple scales, and return a unique pristine sample to Earth unaltered by the atmospheric entry process or terrestrial weathering. The baseline target of MarcoPolo-R is the primitive

  17. The Orbiting Wide-Angle Light Collectors (OWL) Mission for Charged-Particle Astronomy (United States)

    Mitchell, John; Krizmanic, J. F.; Stecker, F. W.; Streitmatter, R. E.


    The space-based OWL mission is designed to perform high-statistics measurements of ultra-high-energy cosmic rays (UHECR) using the Earth's atmosphere as a vast particle calorimeter, furthering the field of charged-particle astronomy. OWL has been developed in formal NASA instrument and mission studies and is comprised of two large telescopes separated by approx.600 km in 1000 km, near-equatorial orbits to stereoscopically image the near-UV air fluorescence emitted by UHECR-induced particle cascades. The High Resolution Fly's Eye (HiRes) Collaboration, and subsequently the Pierre Auger Observatory, recently reported confirmation of the expected Greisen-Zatsepin-Kuzmin (GZK) suppression of the UHECR flux above a few times 10(exp 19) eV. This observation is consistent with the majority of UHECR originating in astrophysical objects and reduces the need to invoke exotic physical processes. Particles observed above the GZK threshold energy must have come from sources within about 100 Mpc from the Earth. The small particle deflection angles expected at UHECR energies, with standard assumptions of extragalactic magnetic fields, are on the order of 1 degree. Thus by observing particles above the GZK threshold with sufficient exposure, there is the potential of identifying and characterizing individual UHECR sources. Auger has reported significant anisotropy in the arrival directions of UHECR at energies above about 6 10(exp 19) eV observed in the South, and a correlation to AGN in the 12th VCV catalog, suggesting that the sources of UHECR are traced by the distribution of luminous matter in the Universe. However, with similar statistics and the same event selection criteria, HiRes observations in the North are consistent with isotropy. Extended observations by Auger-South, by Telescope Array in the North, and possibly by the proposed Auger-North, will further these investigations. However, much greater exposures will be required to fully identify individual sources and

  18. Carbon Observations from Geostationary Earth Orbit as Part of an Integrated Observing System for Atmospheric Composition (United States)

    Edwards, D. P.


    This presentation describes proposed satellite carbon measurements from the CHRONOS mission. The primary goal of this experiment is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. CHRONOS observations would provide measurements not currently available or planned as part of a surface, suborbital and satellite integrated observing system for atmospheric composition over North America. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution, and CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth

  19. An LDEF 2 dust instrument for discrimination between orbital debris and natural particles in near-Earth space (United States)

    Tuzzolino, A. J.; Simpson, J. A.; Mckibben, R. B.; Voss, H. D.; Gursky, H.


    The characteristics of a space dust instrument which would be ideally suited to carry out near-Earth dust measurements on a possible Long Duraction Exposure Facility reflight mission (LDEF 2) is discussed. As a model for the trajectory portion of the instrument proposed for LDEF 2, the characteristics of a SPAce DUSt instrument (SPADUS) currently under development for flight on the USA ARGOS mission to measure the flux, mass, velocity, and trajectory of near-Earth dust is summarized. Since natural (cosmic) dust and man-made dust particles (orbital debris) have different velocity and trajectory distributions, they are distinguished by means of the SPADUS velocity/trajectory information. The SPADUS measurements will cover the dust mass range approximately 5 x 10(exp -12) g (2 microns diameter) to approximately 1 x 10(exp -5) g (200 microns diameter), with an expected mean error in particle trajectory of approximately 7 deg (isotropic flux). Arrays of capture cell devices positioned behind the trajectory instrumentation would provide for Earth-based chemical and isotopic analysis of captured dust. The SPADUS measurement principles, characteristics, its role in the ARGOS mission, and its application to an LDEF 2 mission are summarized.

  20. Circular revisit orbits design for responsive mission over a single target (United States)

    Li, Taibo; Xiang, Junhua; Wang, Zhaokui; Zhang, Yulin


    The responsive orbits play a key role in addressing the mission of Operationally Responsive Space (ORS) because of their capabilities. These capabilities are usually focused on supporting specific targets as opposed to providing global coverage. One subtype of responsive orbits is repeat coverage orbit which is nearly circular in most remote sensing applications. This paper deals with a special kind of repeating ground track orbit, referred to as circular revisit orbit. Different from traditional repeat coverage orbits, a satellite on circular revisit orbit can visit a target site at both the ascending and descending stages in one revisit cycle. This typology of trajectory allows a halving of the traditional revisit time and does a favor to get useful information for responsive applications. However the previous reported numerical methods in some references often cost lots of computation or fail to obtain such orbits. To overcome this difficulty, an analytical method to determine the existence conditions of the solutions to revisit orbits is presented in this paper. To this end, the mathematical model of circular revisit orbit is established under the central gravity model and the J2 perturbation. A constraint function of the circular revisit orbit is introduced, and the monotonicity of that function has been studied. The existent conditions and the number of such orbits are naturally worked out. Taking the launch cost into consideration, optimal design model of circular revisit orbit is established to achieve a best orbit which visits a target twice a day in the morning and in the afternoon respectively for several days. The result shows that it is effective to apply circular revisit orbits in responsive application such as reconnoiter of natural disaster.

  1. Novel Solar Sail Mission Concepts for High-Latitude Earth and Lunar Observation

    NARCIS (Netherlands)

    Heiligers, M.J.; Parker, Jeffrey S.; Macdonald, Malcolm


    This paper proposes the use of solar sail periodic orbits in the Earth-Moon system for ob-servation of the high-latitudes of the Earth and Moon. At the Earth, the high-latitudes will be crucial in answering questions concerning global climate change, monitoring space weather events and ensuring

  2. Satellite orbit determination using satellite gravity gradiometry observations in GOCE mission perspective

    Directory of Open Access Journals (Sweden)

    A. Bobojć


    Full Text Available Between the years 2004 and 2005 the launch of the first gradiometric satellite is planned. This satellite will be an important element of the Gravity Field and Steady – State Ocean Circulation Explorer Mission (GOCE. This mission is one of the reasons for performing the simulation research of the Satellite Gravity Gradiometry. Our work contains the theory description and simulation results of the satellite orbit determination using the gravity tensor observations. In the process of the satellite orbit determination the initial dynamic state vector corrections are obtained. These corrections are estimated by means of the gravity gradiometry measurements. The performed simulations confirm the possibility of satellite orbit determination by means of the gravity tensor observations.Key words. satellite geodesy, satellite gradiometry, satellite orbits

  3. Extension of Earth-Moon libration point orbits with solar sail propulsion (United States)

    Heiligers, Jeannette; Macdonald, Malcolm; Parker, Jeffrey S.


    This paper presents families of libration point orbits in the Earth-Moon system that originate from complementing the classical circular restricted three-body problem with a solar sail. Through the use of a differential correction scheme in combination with a continuation on the solar sail induced acceleration, families of Lyapunov, halo, vertical Lyapunov, Earth-centred, and distant retrograde orbits are created. As the solar sail circular restricted three-body problem is non-autonomous, a constraint defined within the differential correction scheme ensures that all orbits are periodic with the Sun's motion around the Earth-Moon system. The continuation method then starts from a classical libration point orbit with a suitable period and increases the solar sail acceleration magnitude to obtain families of orbits that are parametrised by this acceleration. Furthermore, different solar sail steering laws are considered (both in-plane and out-of-plane, and either fixed in the synodic frame or fixed with respect to the direction of Sunlight), adding to the wealth of families of solar sail enabled libration point orbits presented. Finally, the linear stability properties of the generated orbits are investigated to assess the need for active orbital control. It is shown that the solar sail induced acceleration can have a positive effect on the stability of some orbit families, especially those at the L2 point, but that it most often (further) destabilises the orbit. Active control will therefore be needed to ensure long-term survivability of these orbits.

  4. Space Radiation: The Number One Risk to Astronaut Health beyond Low Earth Orbit

    Directory of Open Access Journals (Sweden)

    Jeffery C. Chancellor


    Full Text Available Projecting a vision for space radiobiological research necessitates understanding the nature of the space radiation environment and how radiation risks influence mission planning, timelines and operational decisions. Exposure to space radiation increases the risks of astronauts developing cancer, experiencing central nervous system (CNS decrements, exhibiting degenerative tissue effects or developing acute radiation syndrome. One or more of these deleterious health effects could develop during future multi-year space exploration missions beyond low Earth orbit (LEO. Shielding is an effective countermeasure against solar particle events (SPEs, but is ineffective in protecting crew members from the biological impacts of fast moving, highly-charged galactic cosmic radiation (GCR nuclei. Astronauts traveling on a protracted voyage to Mars may be exposed to SPE radiation events, overlaid on a more predictable flux of GCR. Therefore, ground-based research studies employing model organisms seeking to accurately mimic the biological effects of the space radiation environment must concatenate exposures to both proton and heavy ion sources. New techniques in genomics, proteomics, metabolomics and other “omics” areas should also be intelligently employed and correlated with phenotypic observations. This approach will more precisely elucidate the effects of space radiation on human physiology and aid in developing personalized radiological countermeasures for astronauts.

  5. Space Radiation: The Number One Risk to Astronaut Health beyond Low Earth Orbit (United States)

    Chancellor, Jeffery C.; Scott, Graham B. I.; Sutton, Jeffrey P.


    Projecting a vision for space radiobiological research necessitates understanding the nature of the space radiation environment and how radiation risks influence mission planning, timelines and operational decisions. Exposure to space radiation increases the risks of astronauts developing cancer, experiencing central nervous system (CNS) decrements, exhibiting degenerative tissue effects or developing acute radiation syndrome. One or more of these deleterious health effects could develop during future multi-year space exploration missions beyond low Earth orbit (LEO). Shielding is an effective countermeasure against solar particle events (SPEs), but is ineffective in protecting crew members from the biological impacts of fast moving, highly-charged galactic cosmic radiation (GCR) nuclei. Astronauts traveling on a protracted voyage to Mars may be exposed to SPE radiation events, overlaid on a more predictable flux of GCR. Therefore, ground-based research studies employing model organisms seeking to accurately mimic the biological effects of the space radiation environment must concatenate exposures to both proton and heavy ion sources. New techniques in genomics, proteomics, metabolomics and other “omics” areas should also be intelligently employed and correlated with phenotypic observations. This approach will more precisely elucidate the effects of space radiation on human physiology and aid in developing personalized radiological countermeasures for astronauts. PMID:25370382

  6. MICROSCOPE Mission: on-orbit assessment of the Drag-Free and Attitude Control System

    DEFF Research Database (Denmark)

    Prieur, Pascal; Lienart, Thomas; Rodrigues, Manuel

    Microscope successfully completed in November 2016 its on-orbit assessment. The paper begins with a brief description of the mission, the challenging performances the DFACS has to comply with and how they led to the hardwareand software design. Then we go through the major phases of the commissio......Microscope successfully completed in November 2016 its on-orbit assessment. The paper begins with a brief description of the mission, the challenging performances the DFACS has to comply with and how they led to the hardwareand software design. Then we go through the major phases...

  7. Rings of earth. [orbiting bands of space debris (United States)

    Goldstein, Richard M.; Randolph, L. W.


    Small particles moving at an orbital velocity of 7.6 kilometers per second can present a considerable hazard to human activity in space. For astronauts outside of the protective shielding of their space vehicles, such particles can be lethal. The powerful radar at NASA's Goldstone Deep Communications Complex was used to monitor such orbital debris. This radar can detect metallic objects as small as 1.8 mm in diameter at 600 km altitude. The results of the preliminary survey show a flux (at 600 km altitude) of 6.4 objects per square kilometer per day of equivalent size of 1.8 mm or larger. Forty percent of the observed particles appear to be concentrated into two orbits. An orbital ring with the same inclination as the radar (35.1 degrees) is suggested. However, an orbital band with a much higher inclination (66 degrees) is also a possibility.

  8. METIS-ESA solar orbiter mission internal straylight analysis (United States)

    Verroi, E.; Da Deppo, V.; Naletto, G.; Fineschi, S.; Antonucci, E.


    METIS is the Multi Element Telescope for Imaging and Spectroscopy for the ESA Solar Orbiter. Its target is the solar corona from a near-Sun orbit in two different spectral bands: the HI UV narrow band at 121.6 nm, and the VL visible light band. METIS adopts a novel inverted externally occulted configuration, where the disk light is shielded by an annular occulter, and an annular aspherical mirror M1 collects the signal coming from the corona. After M1 the coronal light passes through an internal occulter and is then reflected by a second annular mirror M2 toward a narrow filter for the 121.6 nm HI line selection. The visible light reflected by the filter is used to feed a visible light (580 - 640 nm) polarimetric channel. The photospheric light passing through the entrance aperture is back-rejected by a spherical rejection mirror. Since the coronal light is enormously fainter than the photospheric one, a very tough suppression is needed for the internal stray light, in particular the requirement for the stray light suppression is more stringent in the VL than in the UV, because the emission of the corona with respect to the disk emission is different in the two cases, and the requirements are a suppression of at least 10-9 times for the VL and a suppression of at least 10-7 times for the UV channel. This paper presents the stray light analysis for this new coronographic configuration. The complexity of the optomechanical design of METIS, combined with the faintness of the coronal light with respect to the solar disk noise, make a standard ray tracing approach not feasible because it is not sufficient to stop at the first generation of scattered rays in order to check the requirements. Also scattered rays down to the fourth generation must be treated as sources of new scattering light, to analyze the required level of accuracy. If used in a standard ray tracing scattering analysis, this approach is absolutely beyond the computational capabilities today available

  9. The International Space Station: A Low-Earth Orbit (LEO) Test Bed for Advancements in Space and Environmental Medicine (United States)

    Ruttley, Tara M.; Robinson, Julie A.


    Ground-based space analog projects such as the NASA Extreme Environment Mission Operations (NEEMO) can be valuable test beds for evaluation of experimental design and hardware feasibility before actually being implemented on orbit. The International Space Station (ISS) is an closed-system laboratory that orbits 240 miles above the Earth, and is the ultimate extreme environment. Its inhabitants spend hours performing research that spans from fluid physics to human physiology, yielding results that have implications for Earth-based improvements in medicine and health, as well as those that will help facilitate the mitigation of risks to the human body associated with exploration-class space missions. ISS health and medical experiments focus on pre-flight and in-flight prevention, in-flight treatment, and postflight recovery of health problems associated with space flight. Such experiments include those on enhanced medical monitoring, bone and muscle loss prevention, cardiovascular health, immunology, radiation and behavior. Lessons learned from ISS experiments may not only be applicable to other extreme environments that face similar capability limitations, but also serve to enhance standards of care for everyday use on Earth.

  10. Human Missions to Near-Earth Asteroids: An Update on NASA's Current Status and Proposed Activities for Small Body Exploration (United States)

    Abell, P. A.; Mazanek, D. D.; Barbee, B. W.; Mink, R. G.; Landis, R. R.; Adamo, D. R.; Johnson, L. N.; Yeomans, D. K.; Reeves, D. M.; Larman, K. T.; hide


    Introduction: Over the past several years, much attention has been focused on the human exploration of near-Earth asteroids (NEAs). Two independent NASA studies examined the feasibility of sending piloted missions to NEAs, and in 2009, the Augustine Commission identified NEAs as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. More recently the current U.S. presidential administration directed NASA to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. Dynamical Assessment: The current near-term NASA human spaceflight capability is in the process of being defined while the Multi-Purpose Crew Vehicle (MPCV) and Space Launch System (SLS) are still in development. Hence, those NEAs in more accessible heliocentric orbits relative to a minimal interplanetary exploration capability will be considered for the first missions. If total mission durations for the first voyages to NEAs are to be kept to less than one year, with minimal velocity changes, then NEA rendezvous missions ideally will take place within 0.1 AU of Earth (approx about 5 million km or 37 lunar distances). Human Exploration Considerations: These missions would be the first human expeditions to inter-planetary bodies beyond the Earth-Moon system and would prove useful for testing technologies required for human missions to Mars, Phobos and Deimos, and other Solar System destinations. Missions to NEAs would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting detailed scientific investigations of these primitive objects. Current analyses of operational concepts suggest that stay times of 15 to 30 days may be possible at these destinations. In addition, the

  11. Collisional cascading - The limits of population growth in low earth orbit (United States)

    Kessler, Donald J.


    Random collisions between made-made objects in earth orbit will lead to a significant source of orbital debris, but there are a number of uncertainties in these models, and additional analysis and data are required to fully characterize the future environment. However, the nature of these uncertainties are such that while the future environment is uncertain, the fact that collisions will control the future environment is less uncertain. The data that already exist is sufficient to show that cascading collisions will control the future debris environment with no, or very minor increases in the current low-earth-orbit population. Two populations control this process: explosion fragments and expended rocket bodies and payloads. Practices are already changing to limit explosions in low earth orbit; it is necessary to begin limiting the number of expended rocket bodies and payloads in orbit.

  12. Evaluation of Aerodynamic Drag and Torque for External Tanks in Low Earth Orbit

    National Research Council Canada - National Science Library

    Stone, William C; Witzgall, Christoph


    A numerical procedure is described in which the aerodynamic drag and torque in low Earth orbit are calculated for a prototype Space Shuttle external tank and its components, the "LO2" and "LH2" tanks...

  13. Comprehensive NASA Cis-Lunar Earth Moon Libration Orbit Reference and Web Application Project (United States)

    National Aeronautics and Space Administration — To finalize a comprehensive NASA Cis-Lunar / Earth-Moon Libration Orbit Reference and Web Application begun using FY13 IRAD funding approved in May 2013. This GSFC...

  14. Technology Development to Support Human Health and Performance in Exploration Beyond Low Earth Orbit (United States)

    Kundrot, C.E.; Steinberg, S. L.; Charles, J. B.


    In the course of defining the level of risks and mitigating the risks for exploration missions beyond low Earth orbit, NASA s Human Research Program (HRP) has identified the need for technology development in several areas. Long duration missions increase the risk of serious medical conditions due to limited options for return to Earth; no resupply; highly limited mass, power, volume; and communication delays. New space flight compatible medical capabilities required include: diagnostic imaging, oxygen concentrator, ventilator, laboratory analysis (saliva, blood, urine), kidney stone diagnosis & treatment, IV solution preparation and delivery. Maintenance of behavioral health in such an isolated, confined and extreme environment requires new sensory stimulation (e.g., virtual reality) technology. Unobtrusive monitoring of behavioral health and treatment methods are also required. Prolonged exposure to weightlessness deconditions bone, muscle, and the cardiovascular system. Novel exercise equipment or artificial gravity are necessary to prevent deconditioning. Monitoring of the degree of deconditioning is required to ensure that countermeasures are effective. New technologies are required in all the habitable volumes (e.g., suit, capsule, habitat, exploration vehicle, lander) to provide an adequate food system, and to meet human environmental standards for air, water, and surface contamination. Communication delays require the crew to be more autonomous. Onboard decision support tools that assist crew with real-time detection and diagnosis of vehicle and habitat operational anomalies will enable greater autonomy. Multi-use shield systems are required to provide shielding from solar particle events. The HRP is pursuing the development of these technologies in laboratories, flight analog environments and the ISS so that the human health and performance risks will be acceptable with the available resources.

  15. TanDEM-X the Earth surface observation project from space level - basis and mission status

    Directory of Open Access Journals (Sweden)

    Jerzy Wiśniowski


    Full Text Available TanDEM-X is DLR (Deutsches Zentrum für Luft- und Raumfahrt the Earth surface observation project using high-resolution SAR interferometry. It opens a new era in space borne radar remote sensing. The system is based on two satellites: TerraSAR-X (TSX and TanDEM-X (TDX flying on the very close, strictly controlled orbits. This paper gives an overview of the radar technology and overview of the TanDEM-X mission concept which is based on several innovative technologies. The primary objective of the mission is to deliver a global digital elevation model (DEM with an unprecedented accuracy, which is equal to or surpass the HRTI-3 specifications (12 m posting, relative height accuracy ±2 m for slope < 20% and ±4 m for slope > 20% [8]. Beyond that, TanDEM-X provides a highly reconfigurable platform for the demonstration of new radar imaging techniques and applications.[b]Keywords[/b]: remote sensing, Bistatic SAR, digital elevation model (DEM, Helix formation, SAR interferomery, HRTI-3, synchronization

  16. Maximizing the ExoEarth candidate yield from a future direct imaging mission

    Energy Technology Data Exchange (ETDEWEB)

    Stark, Christopher C. [NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Code 667, Greenbelt, MD 20771 (United States); Roberge, Aki; Mandell, Avi [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Robinson, Tyler D., E-mail: [NASA Ames Research Center, Moffett Field, CA 94035 (United States)


    ExoEarth yield is a critical science metric for future exoplanet imaging missions. Here we estimate exoEarth candidate yield using single visit completeness for a variety of mission design and astrophysical parameters. We review the methods used in previous yield calculations and show that the method choice can significantly impact yield estimates as well as how the yield responds to mission parameters. We introduce a method, called Altruistic Yield Optimization, that optimizes the target list and exposure times to maximize mission yield, adapts maximally to changes in mission parameters, and increases exoEarth candidate yield by up to 100% compared to previous methods. We use Altruistic Yield Optimization to estimate exoEarth candidate yield for a large suite of mission and astrophysical parameters using single visit completeness. We find that exoEarth candidate yield is most sensitive to telescope diameter, followed by coronagraph inner working angle, followed by coronagraph contrast, and finally coronagraph contrast noise floor. We find a surprisingly weak dependence of exoEarth candidate yield on exozodi level. Additionally, we provide a quantitative approach to defining a yield goal for future exoEarth-imaging missions.

  17. Space environmental effects on LDEF low Earth orbit exposed graphite reinforced polymer matrix composites (United States)

    George, Pete


    The Long Duration Exposure Facility (LDEF) was deployed on April 7, 1984 in low earth orbit (LEO) at an altitude of 482 kilometers. On board experiments experienced the harsh LEO environment including atomic oxygen (AO), ultraviolet radiation (UV), and thermal cycling. During the 5.8 year mission, the LDEF orbit decayed to 340 kilometers where significantly higher AO concentrations exist. LDEF was retrieved on January 12, 1990 from this orbit. One experiment on board LDEF was M0003, Space Effects on Spacecraft Materials. As a subset of M0003 nearly 500 samples of polymer, metal, and glass matrix composites were flown as the Advanced Composites Experiment M0003-10. The Advanced Composites Experiment is a joint effort between government and industry with the Aerospace Corporation serving as the experiment integrator. A portion of the graphite reinforced polymer matrix composites were furnished by the Boeing Defense and Space Group, Seattle, Washington. Test results and discussions for the Boeing portion of M0003-10 are presented. Experiment and specimen location on the LDEF are presented along with a quantitative summary of the pertinent exposure conditions. Matrix materials selected for the test were epoxy, polysulfone, and polyimide. These composite materials were selected due to their suitability for high performance structural capability in spacecraft applications. Graphite reinforced polymer matrix composites offer higher strength to weight ratios along with excellent dimensional stability. The Boeing space exposed and corresponding ground control composite specimens were subjected to post flight mechanical, chemical, and physical testing in order to determine any changes in critical properties and performance characteristics. Among the more significant findings are the erosive effect of atomic oxygen on leading edge exposed specimens and microcracking in non-unidirectionally reinforced flight specimens.

  18. The Coverage Analysis for Low Earth Orbiting Satellites at Low Elevation


    Shkelzen Cakaj; Bexhet Kamo; Algenti Lala; Alban Rakipi


    Low Earth Orbit (LEO) satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region. The duration of the visibility and the communication vary for each LEO satellite pass over the station, since LEO satellites move too fast over the Earth. The satellite coverage area is defined as a regio...

  19. Investigating fundamental physics and space environment with a dedicated Earth-orbiting spacecraft (United States)

    Peron, Roberto

    -year requirement and thus they need specific arrangements for deorbiting at the end of life or they can simply rely on mother nature for reentry. The goal of this proposed approach is to utilize existing technology developed for acceleration measurement in space and state-of-the-art satellite tracking to precisely determine the orbit of a satellite with well-defined geometrical and mass characteristics (i.e., (A/m) ratio), at the same time accurately measuring over a long period of time the drag deceleration (as well as others non-gravitational effects) acting on the satellite. This will result in a virtually drag-free object that can be exploited to: 1. perform fundamental physics tests by verifying the equation of motion of a test mass in the general relativistic context and placing limits to alternative theories of gravitation; 2. improve the knowledge of selected tidal terms; 3. map, through acceleration measurements, the atmospheric density in the orbital region of interest. In its preliminary incarnation, the satellite would be cylindrical in shape and spinning about its cylinder axis that would be also orthogonal to the orbital plane. The satellite should be placed on a dawn-dusk, sun-synchronous, elliptical orbit spanning the orbital altitudes of interest (e.g., between 500 and 1200 km of altitude). The satellite should be equipped with a 3-axis accelerometer package with an acceleration resolution better than (10^{-11} g) (with (g) the acceleration at the Earth's surface). The expected measurement range is (10^{-8} - 10^{-11} g) considering estimates of drag forces at minimum and maximum solar activity conditions in the altitude range of interest and a preliminary estimate of the satellite (A/m) ratio. The overall concept of the mission will be discussed, concentrating on the fundamental aspects and main scientific return. The main instrumentation to be hosted on-board the spacecraft will be then reviewed, with a focus on current and projected capabilities.

  20. A model perspective on orbital forcing of monsoons and Mediterranean climate using EC-Earth

    NARCIS (Netherlands)

    Bosmans, J.H.C.|info:eu-repo/dai/nl/344765490


    This thesis focuses on orbitally forced changes of monsoons and Mediterranean climate. Changes in the shape of the Earths orbit around the Sun and its rotational axis govern the seasonal and latitudinal distribution of incoming solar radiation on time scales of thousands to millions of years. The

  1. A KAM Tori Algorithm for Earth Satellite Orbits (United States)

    Wiesel, William E.


    This paper offers a new approach for constructing Kolmogorov - Arnold - Moser (KAM) tori for orbits in the full potential for a non-spherical planet. The Hamilton - Jacobi equation is solved numerically by a Newton-Rhapson iteration, achieving convergence to machine precision, and still retaining literal variable dependence. Similar iteration methods allow correcting the orbital frequencies, and permit the calculation of the state transition matrix for the full problem. Some initial numerical examples are offered.

  2. On the possible values of the orbit distance between a near-Earth asteroid and the Earth (United States)

    Gronchi, G. F.; Valsecchi, G. B.


    We consider all the possible trajectories of a near-Earth asteroid (NEA), corresponding to the whole set of heliocentric orbital elements with perihelion distance q ≤ 1.3 au and eccentricity e ≤ 1 (NEA class). For these hypothetical trajectories, we study the range of the values of the distance from the trajectory of the Earth (assumed on a circular orbit) as a function of selected orbital elements of the asteroid. The results of this geometric approach are useful to explain some aspects of the orbital distribution of the known NEAs. We also show that the maximal orbit distance between an object in the NEA class and the Earth is attained by a parabolic orbit, with apsidal line orthogonal to the ecliptic plane. It turns out that the threshold value of q for the NEA class (qmax = 1.3 au) is very close to a critical value, below which the above result is not valid. `Nothing was visible, nor could be visible, to us, except Straight Lines', E. A. Abbott, Flatland.

  3. Deep Interior Mission: Imaging the Interior of Near-Earth Asteroids Using Radio Reflection Tomography (United States)

    Safaeinili, A.; Asphaug, E.; Rodriquez, E.; Gurrola, E.; Belton, M.; Klaasen, K.; Ostro, S.; Plaut, J.; Yeomans, D.


    Near-Earth asteroids are important exploration targets since they provide clues to the evolution of the solar system. They are also of interest since they present a clear danger to Earth. Our mission objective is to image the internal structure of two NEOs using radio reflection tomography (RRT) in order to explore the record of asteroid origin and impact evolution, and to test the fundamental hypothesis that some NEOs are rubble piles rather than consolidated bodies. Our mission s RRT technique is analogous to doing a CAT scan of the asteroid from orbit. Closely sampled radar echoes are processed to yield volumetric maps of mechanical and compositional boundaries, and to measure interior material dielectric properties. The RRT instrument is a radar that operates at 5 and 15 MHz with two 30-m (tip-to-tip) dipole antennas that are used in a cross-dipole configuration. The radar transmitter and receiver electronics have heritage from JPL's MARSIS contribution to Mars Express, and the antenna is similar to systems used in IMAGE and LACE missions. The 5-MHz channel is designed to penetrate greater than 1 km of basaltic rock, and 15-MHz penetrates a few hundred meters or more. In addition to RRT volumetric imaging, we use redundant color cameras to explore the surface expressions of unit boundaries, in order to relate interior radar imaging to what is observable from spacecraft imaging and from Earth. The camera also yields stereo color imaging for geology and RRT-related compositional analysis. Gravity and high fidelity geodesy are used to explore how interior structure is expressed in shape, density, mass distribution and spin. Ion thruster propulsion is utilized by Deep Interior to enable tomographic radar mapping of multiple asteroids. Within the Discovery AO scheduling parameters we identify two targets, S-type 1999 ND43 (approximately 500 m diameter) and V-type 3908 Nyx (approximately 1 km), asteroids whose compositions bracket the diversity of solar system

  4. Large-size space debris flyby in low earth orbits (United States)

    Baranov, A. A.; Grishko, D. A.; Razoumny, Y. N.


    the analysis of NORAD catalogue of space objects executed with respect to the overall sizes of upper-stages and last stages of carrier rockets allows the classification of 5 groups of large-size space debris (LSSD). These groups are defined according to the proximity of orbital inclinations of the involved objects. The orbits within a group have various values of deviations in the Right Ascension of the Ascending Node (RAAN). It is proposed to use the RAANs deviations' evolution portrait to clarify the orbital planes' relative spatial distribution in a group so that the RAAN deviations should be calculated with respect to the concrete precessing orbital plane of the concrete object. In case of the first three groups (inclinations i = 71°, i = 74°, i = 81°) the straight lines of the RAAN relative deviations almost do not intersect each other. So the simple, successive flyby of group's elements is effective, but the significant value of total Δ V is required to form drift orbits. In case of the fifth group (Sun-synchronous orbits) these straight lines chaotically intersect each other for many times due to the noticeable differences in values of semi-major axes and orbital inclinations. The intersections' existence makes it possible to create such a flyby sequence for LSSD group when the orbit of one LSSD object simultaneously serves as the drift orbit to attain another LSSD object. This flyby scheme requiring less Δ V was called "diagonal." The RAANs deviations' evolution portrait built for the fourth group (to be studied in the paper) contains both types of lines, so the simultaneous combination of diagonal and successive flyby schemes is possible. The value of total Δ V and temporal costs were calculated to cover all the elements of the 4th group. The article is also enriched by the results obtained for the flyby problem solution in case of all the five mentioned LSSD groups. The general recommendations are given concerned with the required reserve of total

  5. Metis aboard the Solar Orbiter space mission: Doses from galactic cosmic rays and solar energetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Telloni, Daniele [INAF-Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese (Italy); INFN Section in Florence, Via Giovanni Sansone 1, 50019 Sesto Fiorentino (Italy); Fabi, Michele [INAF-Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese (Italy); University of Urbino, Department of Pure and Applied Sciences, Via Santa Chiara 27, 61029 Urbino (Italy); Grimani, Catia [INFN Section in Florence, Via Giovanni Sansone 1, 50019 Sesto Fiorentino (Italy); University of Urbino, Department of Pure and Applied Sciences, Via Santa Chiara 27, 61029 Urbino (Italy); Antonucci, Ester [INAF-Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese (Italy)


    The aim of this work is to calculate the dose released by galactic cosmic rays (GCRs) and solar energetic particles (SEPs) in the polarimeter of the Multi Element Telescope for Imaging and Spectroscopy (METIS) coronagraph [1] aboard the Solar Orbiter. This investigation is performed with a Monte Carlo method by considering the role of SEP events of proper intensity at a heliocentric distance from the Sun averaged along the spacecraft orbit. Our approach can be extended to other space missions reaching short distances from the Sun, such as Solar Probe Plus. This study indicates that the deposited dose on the whole set of polarimeter lenses and filters during ten years of the Solar Orbiter mission is of about 2000 Gy. For cerium treated lenses, a dose of 10{sup 6} Gy of gamma radiation from a {sup 60}Co source causes a few percent transmittance loss.

  6. Asteroid Retrieval Mission Concept - Trailblazing Our Future in Space and Helping to Protect Us from Earth Impactors (United States)

    Mazanek, Daniel D.; Brohpy, John R.; Merrill, Raymond G.


    The Asteroid Retrieval Mission (ARM) is a robotic mission concept with the goal of returning a small (7 m diameter) near-Earth asteroid (NEA), or part of a large NEA, to a safe, stable orbit in cislunar space using a 50 kW-class solar electric propulsion (SEP) robotic spacecraft (40 kW available to the electric propulsion system) and currently available technologies. The mass of the asteroidal material returned from this mission is anticipated to be up to 1,000 metric tons, depending on the orbit of the target NEA and the thrust-to-weight and control authority of the SEP spacecraft. Even larger masses could be returned in the future as technological capability and operational experience improve. The use of high-power solar electric propulsion is the key enabling technology for this mission concept, and is beneficial or enabling for a variety of space missions and architectures where high-efficiency, low-thrust transfers are applicable. Many of the ARM operations and technologies could also be applicable to, or help inform, planetary defense efforts. These include the operational approaches and systems associated with the NEA approach, rendezvous, and station-keeping mission phases utilizing a low-thrust, high-power SEP spacecraft, along with interacting with, capturing, maneuvering, and processing the massive amounts of material associated with this mission. Additionally, the processed materials themselves (e.g., high-specific impulse chemical propellants) could potentially be used for planetary defense efforts. Finally, a ubiquitous asteroid retrieval and resource extraction infrastructure could provide the foundation of an on call planetary defense system, where a SEP fleet capable of propelling large masses could deliver payloads to deflect or disrupt a confirmed impactor in an efficient and timely manner.

  7. EDOS Evolution to Support NASA Future Earth Sciences Missions (United States)

    Cordier, Guy R.; McLemore, Bruce; Wood, Terri; Wilkinson, Chris


    This paper presents a ground system architecture to service future NASA decadal missions and in particular, the high rate science data downlinks, by evolving EDOS current infrastructure and upgrading high rate network lines. The paper will also cover EDOS participation to date in formulation and operations concepts for the respective missions to understand the particular mission needs and derived requirements such as data volumes, downlink rates, data encoding, and data latencies. Future decadal requirements such as onboard data recorder management and file protocols drive the need to emulate these requirements within the ground system. The EDOS open system modular architecture is scalable to accommodate additional missions using the current sites antennas and future sites as well and meet the data security requirements and fulfill mission's objectives

  8. Measuring the Eccentricity of the Earth's Orbit with a Nail and a Piece of Plywood (United States)

    Lahaye, Thierry


    I describe how to obtain a rather good experimental determination of the eccentricity of the Earth's orbit, as well as the obliquity of the Earth's rotation axis, by measuring, over the course of a year, the elevation of the Sun as a function of time during a day. With a very simple "instrument" consisting of an elementary sundial, first-year…

  9. The Orbit of Planet Earth in the Last 150 Million Years

    NARCIS (Netherlands)

    Noort, van den P.C.


    The structure of the world is a construction of philosophers and scientists. It changed all the time. Nowadays we have a chaotic Solar System. The orbit of Earth changes, therefore, on the very long run. With it changed the UV- radiation on the surface of Earth, influencing the number of mutations.

  10. The Predicted Growth of the Low Earth Orbit Space Debris Environment: An Assessment of Future Risk for Spacecraft (United States)

    Krisko, Paula H.


    Space debris is a worldwide-recognized issue concerning the safety of commercial, military, and exploration spacecraft. The space debris environment includes both naturally occuring meteoroids and objects in Earth orbit that are generated by human activity, termed orbital debris. Space agencies around the world are addressing the dangers of debris collisions to both crewed and robotic spacecraft. In the United States, the Orbital Debris Program Office at the NASA Johnson Space Center leads the effort to categorize debris, predict its growth, and formulate mitigation policy for the environment from low Earth orbit (LEO) through geosynchronous orbit (GEO). This paper presents recent results derived from the NASA long-term debris environment model, LEGEND. It includes the revised NASA sodium potassium droplet model, newly corrected for a factor of two over-estimation of the droplet population. The study indicates a LEO environment that is already highly collisionally active among orbital debris larger than 1 cm in size. Most of the modeled collision events are non-catastrophic (i.e., They lead to a cratering of the target, but no large scale fragmentation.). But they are potentially mission-ending, and take place between impactors smaller than 10 cm and targets larger than 10 cm. Given the small size of the impactor these events would likely be undetectable by present-day measurement means. The activity continues into the future as would be expected. Impact rates of about four per year are predicted by the current study within the next 30 years, with the majority of targets being abandoned intacts (spent upper stages and spacecraft). Still, operational spacecraft do show a small collisional activity, one that increases over time as the small fragment population increases.

  11. The Scale of Exploration: Planetary Missions Set in the Context of Tourist Destinations on Earth (United States)

    Garry, W. B.; Bleacher, L. V.; Bleacher, J. E.; Petro, N. E.; Mest, S. C.; Williams, S. H.


    What if the Apollo astronauts explored Washington, DC, or the Mars Exploration Rovers explored Disney World? We present educational versions of the traverse maps for Apollo and MER missions set in the context of popular tourist destinations on Earth.

  12. High-Performance Data Analysis Tools for Sun-Earth Connection Missions Project (United States)

    National Aeronautics and Space Administration — The Interactive Data Language (IDL) is a standard tool used by many researchers in observational fields. Present day Sun-Earth Connection missions like SOHO, or...

  13. 3D Printing in Zero G Technology Demonstration Mission: Summary of On-Orbit Operations, Material Testing, and Future Work (United States)

    Prater, Tracie; Bean, Quincy; Werkheiser, Niki; Ordonez, Erick; Ledbetter, Frank; Ryan, Richard; Newton, Steve


    Human space exploration to date has been limited to low Earth orbit and the moon. The International Space Station (ISS), an orbiting laboratory 200 miles above the earth, provides a unique and incredible opportunity for researchers to prove out the technologies that will enable humans to safely live and work in space for longer periods of time and venture farther into the solar system. The ability to manufacture parts in-space rather than launch them from earth represents a fundamental shift in the current risk and logistics paradigm for human spaceflight. In particularly, additive manufacturing (or 3D printing) techniques can potentially be deployed in the space environment to enhance crew safety (by providing an on-demand part replacement capability) and decrease launch mass by reducing the number of spare components that must be launched for missions where cargo resupply is not a near-term option. In September 2014, NASA launched the 3D Printing in Zero G technology demonstration mission to the ISS to explore the potential of additive manufacturing for in-space applications and demonstrate the capability to manufacture parts and tools on-orbit. The printer for this mission was designed and operated by the company Made In Space under a NASA SBIR (Small Business Innovation Research) phase III contract. The overarching objectives of the 3D print mission were to use ISS as a testbed to further maturation of enhancing technologies needed for long duration human exploration missions, introduce new materials and methods to fabricate structure in space, enable cost-effective manufacturing for structures and mechanisms made in low-unit production, and enable physical components to be manufactured in space on long duration missions if necessary. The 3D print unit for fused deposition modeling (FDM) of acrylonitrile butadiene styrene (ABS) was integrated into the ISS Microgravity Science Glovebox (MSG) in November 2014 and phase I printing operations took place from

  14. Utilization of landmark data in attitude/orbit determination. [for earth stabilized satellites (United States)

    Siddalingaiah, H.; Desai, P. S.


    A mathematical model is reported for determination of satellite position, velocity, and attitude using landmark coordinates as observables. This model, although developed with respect to earth stabilized missions, Tiros-N and Nimbus-G in particular, is applicable to any earth stabilized satellite in general.

  15. Guidance Scheme for Modulation of Drag Devices to Enable Return from Low Earth Orbit (United States)

    Dutta, Soumyo; Bowes, Angela L.; Cianciolo, Alicia D.; Glass, Christopher E.; Powell, Richard W.


    Passive drag devices provide opportunities to return payloads from low Earth orbits quickly without using onboard propulsive systems to de-orbit the spacecraft. However, one potential disadvantage of such systems has been the lack of landing accuracy. Drag modulation or changing the shape of the drag device during flight offer a way to control the de-orbit trajectory and target a specific landing location. This paper discusses a candidate passive drag based system, called Exo-brake, as well as efforts to model the dynamics of the vehicle as it de-orbits and guidance schemes used to control the trajectory. Such systems can enable quick return of payloads from low Earth orbit assets like the International Space Station without the use of large re-entry cargo capsules or propulsive systems.

  16. Solar Electric and Chemical Propulsion Technology Applications to a Titan Orbiter/Lander Mission (United States)

    Cupples, Michael


    Several advanced propulsion technology options were assessed for a conceptual Titan Orbiter/Lander mission. For convenience of presentation, the mission was broken into two phases: interplanetary and Titan capture. The interplanetary phase of the mission was evaluated for an advanced Solar Electric Propulsion System (SEPS), while the Titan capture phase was evaluated for state-of-art chemical propulsion (NTO/Hydrazine), three advanced chemical propulsion options (LOX/Hydrazine, Fluorine/Hydrazine, high Isp mono-propellant), and advanced tank technologies. Hence, this study was referred to as a SEPS/Chemical based option. The SEPS/Chemical study results were briefly compared to a 2002 NASA study that included two general propulsion options for the same conceptual mission: an all propulsive based mission and a SEPS/Aerocapture based mission. The SEP/Chemical study assumed identical science payload as the 2002 NASA study science payload. The SEPS/Chemical study results indicated that the Titan mission was feasible for a medium launch vehicle, an interplanetary transfer time of approximately 8 years, an advanced SEPS (30 kW), and current chemical engine technology (yet with advanced tanks) for the Titan capture. The 2002 NASA study showed the feasibility of the mission based on a somewhat smaller medium launch vehicle, an interplanetary transfer time of approximately 5.9 years, an advanced SEPS (24 kW), and advanced Aerocapture based propulsion technology for the Titan capture. Further comparisons and study results were presented for the advanced chemical and advanced tank technologies.

  17. Comprehensive evaluation of attitude and orbit estimation using real earth magnetic field data (United States)

    Deutschmann, Julie; Bar-Itzhack, Itzhack


    A single, augmented extended Kalman filter (EKF) which simultaneously and autonomously estimates spacecraft attitude and orbit was developed and tested with simulated and real magnetometer and rate data. Since the earth's magnetic field is a function of time and position, and since time is accurately known, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft's orbit, are a function of orbit and attitude errors. These differences can be used to estimate the orbit and attitude. The test results of the EKF with magnetometer and gyro data from three NASA satellites are presented and evaluated.


    Energy Technology Data Exchange (ETDEWEB)

    Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)


    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

  19. ICARUS mission, next step of coronal exploration after Solar Orbiter and Solar Probe Plus (United States)

    Krasnoselskikh, Vladimir; Tsurutani, Bruce T.; Velli, Marco; Maksimovic, Milan; Balikhin, Mikhael; Dudok de Wit, Thierry; Kretzschmar, Matthieu


    The primary scientific goal of ICARUS (Investigation of Coronal AcceleRation and heating Up to the Sun), a mother-daughter satellite mission, will be to determine how the magnetic _field and plasma dynamics in the outer solar atmosphere give rise to the corona, the solar wind and the entire heliosphere. Reaching this goal will be a Rosetta-stone step, with results broadly applicable within the fields of space plasma physics and astrophysics. Within ESA's Cosmic Vision roadmap, these science goals address Theme 2: How does the solar system work ?" by investigating basic processes occurring From the Sun to the edge of the Solar System". ICARUS will not only advance our understanding of the plasma environment around our the Sun, but also of the numerous magnetically active stars with hot plasma coronae. ICARUS I will perform the first-ever direct in situ measurements of electromagnetic fields, particle acceleration, wave activity, energy distribution and flows directly in the regions where the solar wind emerges from the coronal plasma. ICARUS I will have a perihelion at 1 Solar radius from its surface, it will cross the region where the major energy deposition occurs. The polar orbit of ICARUS I will enable crossing the regions where both the fast and slow wind are generated. It will probe local characteristics of the plasma and provide unique information about the physical processes involved in the creation of the solar wind. ICARUS II will observe this region using remote-sensing instruments, providing simultaneous information about regions crossed by ICARUS I and the solar atmosphere below as observed by solar telescopes. It will thus provide bridges for understanding the magnetic links between the heliosphere and the solar atmosphere. Such information is crucial to our understanding of the plasma physics and electrodynamics of the solar atmosphere. ICARUS II will also play a very important relay role, enabling the radio-link with ICARUS I. It will receive

  20. Sentinel-3 coverage-driven mission design: Coupling of orbit selection and instrument design (United States)

    Cornara, S.; Pirondini, F.; Palmade, J. L.


    The first satellite of the Sentinel-3 series was launched in February 2016. Sentinel-3 payload suite encompasses the Ocean and Land Colour Instrument (OLCI) with a swath of 1270 km, the Sea and Land Surface Temperature Radiometer (SLSTR) yielding a dual-view scan with swaths of 1420 km (nadir) and 750 km (oblique view), the Synthetic Aperture Radar Altimeter (SRAL) working in Ku-band and C-band, and the dual-frequency Microwave Radiometer (MWR). In the early stages of mission and system design, the main driver for the Sentinel-3 reference orbit selection was the requirement to achieve a revisit time of two days or less globally over ocean areas with two satellites (i.e. 4-day global coverage with one satellite). The orbit selection was seamlessly coupled with the OLCI instrument design in terms of field of view (FoV) definition driven by the observation zenith angle (OZA) and sunglint constraints applied to ocean observations. The criticality of the global coverage requirement for ocean monitoring derives from the sunglint phenomenon, i.e. the impact on visible channels of the solar ray reflection on the water surface. This constraint was finally overcome thanks to the concurrent optimisation of the orbit parameters, notably the Local Time at Descending Node (LTDN), and the OLCI instrument FoV definition. The orbit selection process started with the identification of orbits with short repeat cycle (2-4 days), firstly to minimise the time required to achieve global coverage with existing constraints, and then to minimise the swath required to obtain global coverage and the maximum required OZA. This step yielded the selection of a 4-day repeat cycle orbit, thus allowing 2-day coverage with two adequately spaced satellites. Then suitable candidate orbits with higher repeat cycles were identified in the proximity of the selected altitudes and the reference orbit was ultimately chosen. Rationale was to keep the swath for global coverage as close as possible to the

  1. An approach for finding long period elliptical orbits for precursor SEI missions (United States)

    Fraietta, Michael F.; Bond, Victor R.


    Precursors for Solar System Exploration Initiative (SEI) missions may require long period elliptical orbits about a planet. These orbits will typically have periods on the order of tens to hundreds of days. Some potential uses for these orbits may include the following: studying the effects of galactic cosmic radiation, parking orbits for engineering and operational test of systems, and ferrying orbits between libration points and low altitude orbits. This report presents an approach that can be used to find these orbits. The approach consists of three major steps. First, it uses a restricted three-body targeting algorithm to determine the initial conditions which satisfy certain desired final conditions in a system of two massive primaries. Then the initial conditions are transformed to an inertial coordinate system for use by a special perturbation method. Finally, using the special perturbation method, other perturbations (e.g., sun third body and solar radiation pressure) can be easily incorporated to determine their effects on the nominal trajectory. An algorithm potentially suitable for on-board guidance will also be discussed. This algorithm uses an analytic method relying on Chebyshev polynomials to compute the desired position and velocity of the satellite as a function of time. Together with navigation updates, this algorithm can be implemented to predict the size and timing for AV corrections.

  2. Logistics Reduction and Repurposing Beyond Low Earth Orbit (United States)

    Ewert, Michael K.; Broyan, James L., Jr.


    All human space missions, regardless of destination, require significant logistical mass and volume that is strongly proportional to mission duration. Anything that can be done to reduce initial mass and volume of supplies or reuse items that have been launched will be very valuable. Often, the logistical items require disposal and represent a trash burden. Logistics contributions to total mission architecture mass can be minimized by considering potential reuse using systems engineering analysis. In NASA's Advanced Exploration Systems "Logistics Reduction and Repurposing Project," various tasks will reduce the intrinsic mass of logistical packaging, enable reuse and repurposing of logistical packaging and carriers for other habitation, life support, crew health, and propulsion functions, and reduce or eliminate the nuisance aspects of trash at the same time. Repurposing reduces the trash burden and eliminates the need for hardware whose function can be provided by use of spent logistical items. However, these reuse functions need to be identified and built into future logical systems to enable them to effectively have a secondary function. These technologies and innovations will help future logistics systems to support multiple exploration missions much more efficiently.

  3. GOCE : The first seismometer in orbit around the Earth

    NARCIS (Netherlands)

    Garcia, R.F.; Bruinsma, S.; Lognonné, P.; Doornbos, E.N.; Cachoux, F.


    The first in situ sounding of a post-seismic infrasound wavefront is presented, using data from the GOCE mission. The atmospheric infrasounds following the great Tohoku earthquake (on 11 March 2011) induce variations of air density and vertical acceleration of the GOCE platform. These signals are

  4. Development of Venus Balloon Seismology Missions Through Earth Analog Experiments (United States)

    Krishnamoorthy, S.; Komjathy, A.; Cutts, J. A.; Pauken, M. T.; Garcia, R. F.; Mimoun, D.; Jackson, J. M.; Kedar, S.; Smrekar, S. E.; Hall, J. L.


    The study of a planet’s seismic activity is central to the understanding of its internal structure. We discuss advances made through Earth analog testing for performing remote seismology on Venus using balloons floated in the mid-atmosphere.

  5. Choosing NEO mission targets: current knowledge and future Earth-based observation opportunities


    Fitzsimmons, A.; Harris, A. W.; Eggl, S.; Perna, D.


    NEOShield is a consortium of 13 research institutes, universities and industrial partners from 6 countries. The aim of the project is to explore mitigation options in the event that a NEO is found to be on a potential collision course with Earth, and to pave the way for demonstration missions to test proposed mitigation techniques. Finding an accessible and appropriate target NEO for a demonstration mission is an important aspect of mission design. Targets for NEOShield and other potential...

  6. Environmental Durability Issues for Solar Power Systems in Low Earth Orbit (United States)

    Degroh, Kim K.; Banks, Bruce A.; Smith, Daniela C.


    Space solar power systems for use in the low Earth orbit (LEO) environment experience a variety of harsh environmental conditions. Materials used for solar power generation in LEO need to be durable to environmental threats such as atomic oxygen, ultraviolet (UV) radiation, thermal cycling, and micrometeoroid and debris impact. Another threat to LEO solar power performance is due to contamination from other spacecraft components. This paper gives an overview of these LEO environmental issues as they relate to space solar power system materials. Issues addressed include atomic oxygen erosion of organic materials, atomic oxygen undercutting of protective coatings, UV darkening of ceramics, UV embrittlement of Teflon, effects of thermal cycling on organic composites, and contamination due to silicone and organic materials. Specific examples of samples from the Long Duration Exposure Facility (LDEF) and materials returned from the first servicing mission of the Hubble Space Telescope (HST) are presented. Issues concerning ground laboratory facilities which simulate the LEO environment are discussed along with ground-to-space correlation issues.

  7. Take off with NASA's Kepler Mission!: The Search for Other "Earths" (United States)

    Koch, David; DeVore, Edna K.; Gould, Alan; Harman, Pamela


    Humans have long wondered about life in the universe. Are we alone? Is Earth unique? What is it that makes our planet a habitable one, and are there others like Earth? NASA's Kepler Mission seeks the answers to these questions. Kepler is a space-based, specially designed 0.95 m aperture telescope. Launching in 2009, Kepler is NASA's first mission…

  8. Application of KAM Theorem to Earth Orbiting Satellites (United States)


    kids , for constantly reminding me that there was more than just school to keep me busy. Bryan D. Little v Table of Contents Page Abstract...Gunter, Z. Kang, P. Nagel, R. Pastor , T. Pekker, S. Poole, and F. Wang. “GGM02 An im- proved Earth gravity field model from GRACE”. Journal of Geodesy

  9. Atomic Oxygen Erosion Yield Prediction for Spacecraft Polymers in Low Earth Orbit (United States)

    Banks, Bruce A.; Backus, Jane A.; Manno, Michael V.; Waters, Deborah L.; Cameron, Kevin C.; deGroh, Kim K.


    The ability to predict the atomic oxygen erosion yield of polymers based on their chemistry and physical properties has been only partially successful because of a lack of reliable low Earth orbit (LEO) erosion yield data. Unfortunately, many of the early experiments did not utilize dehydrated mass loss measurements for erosion yield determination, and the resulting mass loss due to atomic oxygen exposure may have been compromised because samples were often not in consistent states of dehydration during the pre-flight and post-flight mass measurements. This is a particular problem for short duration mission exposures or low erosion yield materials. However, as a result of the retrieval of the Polymer Erosion and Contamination Experiment (PEACE) flown as part of the Materials International Space Station Experiment 2 (MISSE 2), the erosion yields of 38 polymers and pyrolytic graphite were accurately measured. The experiment was exposed to the LEO environment for 3.95 years from August 16, 2001 to July 30, 2005 and was successfully retrieved during a space walk on July 30, 2005 during Discovery s STS-114 Return to Flight mission. The 40 different materials tested (including Kapton H fluence witness samples) were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The MISSE 2 PEACE Polymers experiment used carefully dehydrated mass measurements, as well as accurate density measurements to obtain accurate erosion yield data for high-fluence (8.43 1021 atoms/sq cm). The resulting data was used to develop an erosion yield predictive tool with a correlation coefficient of 0.895 and uncertainty of +/-6.3 10(exp -25)cu cm/atom. The predictive tool utilizes the chemical structures and physical properties of polymers to predict in-space atomic oxygen erosion yields. A predictive tool concept (September 2009 version) is presented which represents an improvement over an earlier (December 2008) version.

  10. The Advanced Microwave Scanning Radiometer-Earth Observing System Data Products from the Aqua Mission (United States)

    Conway, D.; Troisi, V.; Marquis, M.; Armstrong, R.; Stroeve, J.; Maslanik, J.; Axford, Y.; Wolfe, J.


    The Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) is scheduled to launch on NASA's Aqua Satellite in early 2002. The Aqua mission is an important part of the NASA Earth Science Enterprise (ESE). The Aqua mission provides a multi-disciplinary study of the Earth's atmospheric, oceanic, cryospheric, and land processes and their relationship to global change. With six instruments aboard, the Aqua Satellite will travel in a polar, sun-synchronous orbit. The AMSR-E will measure passive microwave radiation, allowing for derivation of many geophysical parameters, including cloud properties, radiative energy flux, precipitation, land surface wetness, sea surface temperatures, sea ice, snow cover, and sea surface wind fields. The AMSR-E has much greater spatial resolution than previous passive microwave radiometers: approximately double the spatial resolution of the Scanning Multichannel Microwave Radiometer (SMMR) and the Special Sensor Microwave/Imager (SSM/I). Further, the AMSR-E combines in one sensor all the channels that SMMR and SSM/I had individually. The AMSR-E has the following frequencies (in GHz): 6.9, 10.7, 18.7, 23.8, 36.5, and 89. The level 1A data product will contain chronological antenna temperature count data. The level 2A data product will contain spatially-resampled brightness temperatures (in global swath format) at resolutions of 56, 38, 21, 12 and 5.4 km. Level 2B data will include ocean, soil moisture, and rain products. Level 3 data will include gridded ocean, soil moisture, and rain products; gridded snow water equivalent products; gridded brightness temperatures; and gridded sea ice concentration and snow depth products. The National Space Agency of Japan (NASDA) will process level 0 data to level 1A data. The AMSR-E Science Investigator-led Processing System (SIPS) will process the level 1A data product to level 2 and 3 data products. The National Snow and Ice Data Center (NSIDC) will archive and distribute all AMSR

  11. COMPASS Final Report: Saturn Moons Orbiter Using Radioisotope Electric Propulsion (REP): Flagship Class Mission (United States)

    Oleson, Steven R.; McGuire, Melissa L.


    The COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) team was approached by the NASA Glenn Research Center (GRC) In-Space Project to perform a design session to develop Radioisotope Electric Propulsion (REP) Spacecraft Conceptual Designs (with cost, risk, and reliability) for missions of three different classes: New Frontier s Class Centaur Orbiter (with Trojan flyby), Flagship, and Discovery. The designs will allow trading of current and future propulsion systems. The results will directly support technology development decisions. The results of the Flagship mission design are reported in this document

  12. Efficient methods for determining precise orbits of low Earth orbiters using the Global Positioning System (United States)

    Bock, Heike

    The main part of this work dealt with the development and evaluation of efficient methods for precise orbit determination of LEOs. A kinematic approach using GPS zero-difference observations was developed (program LEOKIN) and a procedure for generation of dynamic and reduced-dynamic orbits was presented (program SATORB). The procedures have been tested using long GPS data series gathered by two LEO satellites, namely CHAMP and SAC-C. An external comparison was available for the time interval of the eleven days of the IGS CHAMP test campaign (May 20 to 30, 2001). The orbit solution generated at the Technical University of Munich (TUM), Germany, using the Bernese GPS Software was used for this purpose. The TUM-solution is believed to be one of the best solutions contributing to the IGS test campaign. Comparisons with this solution showed that both our best kinematic trajectory and a post-fit reduced-dynamic orbit based on this kinematic solution compare within an RMS error per coordinate (of a Helmert transformation) of about 10 cm with the TUM-solutions. This indicates that LEO orbits with a quality of about 10 cm result from our analyses. The goal of developing efficient methods for precise orbit determination of LEOs is therefore achieved with the zero-difference kinematic point positioning procedure in LEOKIN and the program SATORB to generate reduced-dynamic orbits. It is worth mentioning that the procedure, when using only code observations as input, results in reduced-dynamic orbits with a qualitiy of already 30 cm RMS.

  13. Propulsion options for very low Earth orbit microsatellites (United States)

    Leomanni, Mirko; Garulli, Andrea; Giannitrapani, Antonio; Scortecci, Fabrizio


    The growing competitiveness in the commercial space market has raised the interest in operating small spacecraft at very low altitudes. To make this feasible, the space industry has started developing propulsion options tailored specifically to these platforms. This paper presents a review of emerging micropropulsion technologies and evaluates their applicability to microsatellite missions in the altitude range 250-500 km. The results of the proposed analysis are demonstrated on two different remote sensing applications.

  14. Understanding Spacecraft Agility for Orbit Transfers on the Dawn Low-thrust Mission (United States)

    Smith, Brett A.; Vanelli, C. Anthony; Lee, Allan Y.


    Conventional maneuver design processes were inadequate. Long thrusting durations with the small force of SEP. Increased coupling between ACS and NAV teams. Definition of quantifiable constraints proved impractical. Specifically for the Dawn mission, because of the attitude steering algorithm. A time-efficient simulation tool, qSTAT, was developed and allowed fast verification of candidate thrust profile designs. This approach allowed Dawn to overcome the complications of low-thrust orbit transfers.

  15. Optimization of the Orbiting Wide-Angle Light Collectors (OWL) Mission for Charged-Particle and Neutrino Astronomy (United States)

    Krizmanic, John F.; Mitchell, John W.; Streitmatter, Robert E.


    OWL [1] uses the Earth's atmosphere as a vast calorimeter to fully enable the emerging field of charged-particle astronomy with high-statistics measurements of ultra-high-energy cosmic rays (UHECR) and a search for sources of UHE neutrinos and photons. Confirmation of the Greisen-Zatsepin-Kuzmin (GZK) suppression above approx. 4 x 10(exp 19) eV suggests that most UHECR originate in astrophysical objects. Higher energy particles must come from sources within about 100 Mpc and are deflected by approx. 1 degree by predicted intergalactic/galactic magnetic fields. The Pierre Auger Array, Telescope Array and the future JEM-EUSO ISS mission will open charged-particle astronomy, but much greater exposure will be required to fully identify and measure the spectra of individual sources. OWL uses two large telescopes with 3 m optical apertures and 45 degree FOV in near-equatorial orbits. Simulations of a five-year OWL mission indicate approx. 10(exp 6) sq km/ sr/ yr of exposure with full aperture at approx. 6 x 10(exp 19) eV. Observations at different altitudes and spacecraft separations optimize sensitivity to UHECRs and neutrinos. OWL's stereo event reconstruction is nearly independent of track inclination and very tolerant of atmospheric conditions. An optional monocular mode gives increased reliability and can increase the instantaneous aperture. OWL can fully reconstruct horizontal and upward-moving showers and so has high sensitivity to UHE neutrinos. New capabilities in inflatable structures optics and silicon photomultipliers can greatly increase photon sensitivity, reducing the energy threshold for n detection or increasing viewed area using a higher orbit. Design trades between the original and optimized OWL missions and the enhanced science capabilities are described.

  16. What's New for the Orbiting Carbon Observatory-2? A Summary of Changes between the Original and Re-flight Missions (United States)

    Boland, S. W.; Kahn, P. B.


    The original Orbiting Carbon Observatory mission was lost in 2009 when the spacecraft failed to achieve orbit due to a launch vehicle failure. In 2010, NASA authorized a re-flight mission, known as the Orbiting Carbon Observatory-2 (OCO-2) mission, with direction to re-use the original hardware, designs, drawings, documents, and procedures wherever possible in order to minimize cost, schedule, and performance risk. During implementation, it was realized that some changes were required due to parts obsolescence, incorporation of lessons learned from the original OCO mission, and to provide optimal science return. In response to the OCO and Glory launch vehicle failures, a change in launch vehicle was also recently announced. A summary of changes, including those to hardware, orbit, and launch vehicle is provided, along with rationale, implementation approach, and impact (if any) on mission science.

  17. Atmospheric attenuation relative to earth-viewing orbital sensors. [atmospheric moisture effects on microwaves (United States)

    Brown, S. C.; Jayroe, R. R., Jr.


    Earth viewing space missions offer exciting new possibilities in several earth resources disciplines - geography, hydrology, agriculture, geology, and oceanography, to name a few. A most useful tool in planning experiments and applying space technology to earth observation is a statistical description of atmospheric parameters. Four dimensional atmospheric models and a world wide cloud model are used to produce atmospheric attenuation models to predict degradation effects for all classes of sensors for application to earth sensing experiments from spaceborne platforms. To insure maximum utility and application of these products, the development of an interaction model of microwave energy and atmospheric variables provides a complete description of the effects of atmospheric moisture upon microwaves.

  18. A review of research in low earth orbit propellant collection (United States)

    Singh, Lake A.; Walker, Mitchell L. R.


    This comprehensive review examines the efforts of previous researchers to develop concepts for propellant-collecting spacecraft, estimate the performance of these systems, and understand the physics involved. Rocket propulsion requires the spacecraft to expend two fundamental quantities: energy and propellant mass. A growing number of spacecraft collect the energy they need to execute propulsive maneuvers in-situ with solar panels. In contrast, every spacecraft using rocket propulsion has carried all of the propellant mass needed for the mission from the ground, which limits the range and mission capabilities. Numerous researchers have explored the concept of collecting propellant mass while in space. These concepts have varied in scale and complexity from chemical ramjets to fusion-driven interstellar vessels. Research into propellant-collecting concepts occurred in distinct eras. During the Cold War, concepts tended to be large, complex, and nuclear powered. After the Cold War, concepts transitioned to solar power sources and more effort has been devoted to detailed analysis of specific components of the propellant-collecting architecture. By detailing the major contributions and limitations of previous work, this review concisely presents the state-of-the-art and outlines five areas for continued research. These areas include air-compatible cathode technology, techniques to improve propellant utilization on atmospheric species, in-space compressor and liquefaction technology, improved hypersonic and hyperthermal free molecular flow inlet designs, and improved understanding of how design parameters affect system performance.

  19. Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.


    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  20. Free space laser communication experiments from Earth to the Lunar Reconnaissance Orbiter in lunar orbit. (United States)

    Sun, Xiaoli; Skillman, David R; Hoffman, Evan D; Mao, Dandan; McGarry, Jan F; McIntire, Leva; Zellar, Ronald S; Davidson, Frederic M; Fong, Wai H; Krainak, Michael A; Neumann, Gregory A; Zuber, Maria T; Smith, David E


    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  1. Application of Solar-Electric Propulsion to Robotic Missions in Near-Earth Space (United States)

    Woodcock, Gordon R.; Dankanich, John


    Interest in applications of solar electric propulsion (SEP) is increasing. Application of SEP technology is favored when: (1) the mission is compatible with low-thrust propulsion, (2) the mission needs high total delta V such that chemical propulsion is disadvantaged; and (3) performance enhancement is needed. If all such opportunities for future missions are considered, many uses of SEP are likely. Representative missions are surveyed and several SEP applications selected for analysis, including orbit raising, lunar science and robotic exploration, and planetary science. These missions span SEP power range from 10 kWe to about 100 kWe. A SEP design compatible with small inexpensive launch vehicles, and capable of lunar science missions, is presented. Modes of use and benefits are described, and potential SEP evolution is discussed.

  2. Long-Term Cryogenic Propellant Storage for the Titan Orbiter Polar Surveyor (TOPS) Mission (United States)

    Mustafi, Shuvo; Francis, John; Li, Xiaoyi; DeLee, Hudson; Purves, Lloyd; Willis, Dewey; Nixon, Conor; Mcguinness, Dan; Riall, Sara; Devine, Matt; hide


    Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LOX) can dramatically enhance NASAs ability to explore the solar system because of their superior specific impulse (Isp) capability. Although these cryogenic propellants can be challenging to manage and store, they allow significant mass advantages over traditional hypergolic propulsion systems and are therefore technically enabling for many planetary science missions. New cryogenic storage techniques such as subcooling and the use of advanced insulation and low thermal conductivity support structures will allow for the long term storage and use of cryogenic propellants for solar system exploration and hence allow NASA to deliver more payloads to targets of interest, launch on smaller and less expensive launch vehicles, or both. Employing cryogenic propellants will allow NASA to perform missions to planetary destinations that would not be possible with the use of traditional hypergolic propellants. These new cryogenic storage technologies were implemented in a design study for the Titan Orbiter Polar Surveyor (TOPS) mission, with LH2 and LOX as propellants, and the resulting spacecraft design was able to achieve a 43 launch mass reduction over a TOPS mission, that utilized a conventional hypergolic propulsion system with mono-methyl hydrazine (MMH) and nitrogen tetroxide (NTO) propellants. This paper describes the cryogenic propellant storage design for the TOPS mission and demonstrates how these cryogenic propellants are stored passively for a decade-long Titan mission.

  3. Preliminary GN&C Design for the On-Orbit Autonomous Assembly of Nanosatellite Demonstration Mission (United States)

    Pei, Jing; Walsh, Matt; Roithmayr, Carlos; Karlgaard, Chris; Peck, Mason; Murchison, Luke


    Small spacecraft autonomous rendezvous and docking (ARD) is an essential technology for future space structure assembly missions. The On-orbit Autonomous Assembly of Nanosatellites (OAAN) team at NASA Langley Research Center (LaRC) intends to demonstrate the technology to autonomously dock two nanosatellites to form an integrated system. The team has developed a novel magnetic capture and latching mechanism that allows for docking of two CubeSats without precise sensors and actuators. The proposed magnetic docking hardware not only provides the means to latch the CubeSats, but it also significantly increases the likelihood of successful docking in the presence of relative attitude and position errors. The simplicity of the design allows it to be implemented on many CubeSat rendezvous missions. Prior to demonstrating the docking subsystem capabilities on orbit, the GN&C subsystem should have a robust design such that it is capable of bringing the CubeSats from an arbitrary initial separation distance of as many as a few thousand kilometers down to a few meters. The main OAAN Mission can be separated into the following phases: 1) Launch, checkout, and drift, 2) Far-Field Rendezvous or Drift Recovery, 3) Proximity Operations, 4) Docking. This paper discusses the preliminary GN&C design and simulation results for each phase of the mission.

  4. The Megha-Tropiques mission: a review after three years in orbit

    Directory of Open Access Journals (Sweden)

    Rémy eRoca


    Full Text Available The Megha-Tropiques mission is operating a suite of payloads dedicated to the documentation of the water and energy cycles in the intertropical region in a low inclination orbit. The satellite was launched in October, 2011 and we here review the scientific activity after the first three years of the mission. The microwave sounder (SAPHIR and the broad band radiometer (SCARAB are functioning nominally and exhibit instrumental performances well within the original specifications. The microwave imager, MADRAS, stopped acquisition of scientific data on January 26th, 2013 due to a mechanical failure. During its 16 months of operation, this radiometer experienced electrical issues making its usage difficult and delayed its validation. A suite of geophysical products has been retrieved from the Megha-Tropiques payloads, ranging from TOA radiative flux to water vapor profiles and instantaneous rain rates. Some of these geophysical products have been merged with geostationary data to provide, for instance, daily accumulation of rainfall all over the intertropical region. These products compare favorably with references from ground based or space-borne observation systems. The contribution of the mission unique orbit to its scientific objectives is investigated. Preliminary studies indicate a positive impact on both, humidity Numerical Weather Prediction forecasts thanks to the assimilation of SAPHIR Level 1 data, and on the rainfall estimation derived from the Global Precipitation Mission constellation. After a long commissioning phase, most of the data and the geophysical products suite are validated and readily available for further scientific investigation by the international community.

  5. The PROCESS experiment: amino and carboxylic acids under Mars-like surface UV radiation conditions in low-earth orbit. (United States)

    Noblet, Audrey; Stalport, Fabien; Guan, Yuan Yong; Poch, Olivier; Coll, Patrice; Szopa, Cyril; Cloix, Mégane; Macari, Frédérique; Raulin, Francois; Chaput, Didier; Cottin, Hervé


    The search for organic molecules at the surface of Mars is a top priority of the next Mars exploration space missions: Mars Science Laboratory (NASA) and ExoMars (ESA). The detection of organic matter could provide information about the presence of a prebiotic chemistry or even biological activity on this planet. Therefore, a key step in interpretation of future data collected by these missions is to understand the preservation of organic matter in the martian environment. Several laboratory experiments have been devoted to quantifying and qualifying the evolution of organic molecules under simulated environmental conditions of Mars. However, these laboratory simulations are limited, and one major constraint is the reproduction of the UV spectrum that reaches the surface of Mars. As part of the PROCESS experiment of the European EXPOSE-E mission on board the International Space Station, a study was performed on the photodegradation of organics under filtered extraterrestrial solar electromagnetic radiation that mimics Mars-like surface UV radiation conditions. Glycine, serine, phthalic acid, phthalic acid in the presence of a mineral phase, and mellitic acid were exposed to these conditions for 1.5 years, and their evolution was determined by Fourier transform infrared spectroscopy after their retrieval. The results were compared with data from laboratory experiments. A 1.5-year exposure to Mars-like surface UV radiation conditions in space resulted in complete degradation of the organic compounds. Half-lives between 50 and 150 h for martian surface conditions were calculated from both laboratory and low-Earth orbit experiments. The results highlight that none of those organics are stable under low-Earth orbit solar UV radiation conditions.

  6. Investigation of Teflon FEP Embrittlement on Spacecraft in Low Earth Orbit (United States)

    deGroh, Kim K.; Smith, Daniela C.


    Teflon(registered trademark) FEP (fluorinated ethylene-propylene) is commonly used on exterior spacecraft surfaces in the low Earth orbit (LEO) environment for thermal control. Silverized or aluminized FEP is used for the outer layer of thermal control blankets because of its low solar absorptance and high thermal emittance. FEP is also preferred over other spacecraft polymers because of its relatively high resistance to atomic oxygen erosion. Because of its low atomic oxygen erosion yield, FEP has not been protected in the space environment. Recent, long term space exposures such as on the Long Duration Exposure Facility (LDEF, 5.8 years in space), and the Hubble Space Telescope (HST, after 3.6 years in space) have provided evidence of LEO environmental degradation of FEP. These exposures provide unique opportunities for studying environmental degradation because of the long durations and the different conditions (such as differences in altitude) of the exposures. Samples of FEP from LDEF and from HST (retrieved during its first servicing mission) have been evaluated for solar induced embrittlement and for synergistic effects of solar degradation and atomic oxygen. Micro-indenter results indicate that the surface hardness increased as the ratio of atomic oxygen fluence to solar fluence decreased for the LDEF samples. FEP multilayer insulation (MLI) retrieved from HST provided evidence of severe embrittlement on solar facing surfaces. Micro-indenter measurements indicated higher surface hardness values for these samples than LDEF samples, but the solar exposures were higher. Cracks induced during bend testing were significantly deeper for the HST samples with the highest solar exposure than for LDEF samples with similar atomic oxygen fluence to solar fluence ratios. If solar fluences are compared, the LDEF samples appear as damaged as HST samples, except that HST had deeper induced cracks. The results illustrate difficulties in comparing LEO exposed materials from

  7. Long-Duration Human Habitation Beyond Low-Earth Orbit: Why is the Near Future Critical? (United States)

    Thronson, Harley A.; Lester, Daniel; Hatfield, C. A.


    For more than a decade, habitation systems capable of comfortable human occupation and effective operations beyond low-Earth orbit (LEO) for more than a few weeks have been a priority recommendation to NASA. This capability is a lynch pin for human exploration beyond the Earth-Moon system. Here we describe briefly some relevant concepts and discuss justifications in the current political and financial environment for why near-term human habitation systems beyond LEO is an imperative.

  8. Comprehensive Evaluation of Attitude and Orbit Estimation Using Actual Earth Magnetic Field Data (United States)

    Deutschmann, Julie K.; Bar-Itzhack, Itzhack Y.


    A single, augmented Extended Kalman Filter (EKF), which simultaneously and autonomously estimates spacecraft attitude and orbit has been developed and successfully tested with real magnetometer and gyro data only. Because the earth magnetic field is a function of time and position, and because time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both orbit and attitude errors. Thus, conceivably these differences could be used to estimate both orbit and attitude; an observability study validated this assumption. The results of testing the EKF with actual magnetometer and gyro data, from four satellites supported by the NASA Goddard Space Flight Center (GSFC) Guidance, Navigation, and Control Center, are presented and evaluated. They confirm the assumption that a single EKF can estimate both attitude and orbit when using gyros and magnetometers only.

  9. Probable Rotation States of Rocket Bodies in Low Earth Orbit (United States)

    Ojakangas, G.; Anz-Meador, P.; Cowardin, H.


    In order for Active Debris Removal to be accomplished, it is critically important to understand the probable rotation states of orbiting, spent rocket bodies (RBs). However, rotational dynamics is non-intuitive and misconceptions are common. Determinations of rotation and precession rates from light curves have been published that are inconsistent with the theory presented here. In a state of free precession, the total angular momentum of the object is constant, while kinetic energy decreases due to internal friction, approaching rotation about the axis of maximum inertia. For solid internal friction the timescale is hundreds to thousands of years for quality factors of ~100 and assuming metallic rigidities, but for friction in partially-filled liquid fuel tanks we predict that the preferred rotational state is approached rapidly, within days to months. However, history has shown that theoretical predictions of the timescale have been notoriously inaccurate. In free precession, the 3-1-3 Euler angle rates dphi/dt (precession rate of long axis about fixed angular momentum with cone angle theta) and dpsi/dt (roll rate around long axis) have comparable magnitudes until very close to theta=pi/2, so that otherwise the true rotation period is not simply twice the primary light curve period. Furthermore dtheta/dt, nonzero due to friction, becomes asymptotically smaller as theta=pi/2 is approached, so that theta can linger within several degrees of flat spin for a relatively long time. Such a condition is likely common, and cannot be distinguished from the wobble of a cylinder with a skewed inertia tensor unless the RB has non-axisymmetric reflectivity characteristics. For an RB of known dimensions, a given value of theta fixes the relative values of dpsi/dt and dphi/dt. In forced precession, the angular momentum precesses about a symmetry axis defined by the relevant torque. However, in LEO, only gravity gradient and magnetic eddy current torques are dominant, and these

  10. Direct transfer trajectory design options for interplanetary orbiter missions using an iterative patched conic method (United States)

    Parvathi, S. P.; Ramanan, R. V.


    In a direct interplanetary transfer, the spacecraft moves from a parking orbit of the departure planet to a parking orbit of the arrival planet. The transfer trajectory must be designed such that the specified arrival parking orbit conditions are achieved. For a fixed departure epoch and flight duration, there are four distinct transfer trajectory design options in a direct transfer. The conventional patched conic method, the most widely used analytical trajectory design method, does not identify these design options. An iterative patched conic method that identifies these distinct design options is developed and presented in this paper. This method involves two iterative processes: (i) iteration on the hyperbolic orbit characteristics using an analytical tuning strategy to achieve the hyperbolic excess velocity vector at the patch point, (ii) iteration on the patch points at the sphere of influence. The performance of the proposed method is compared with the conventional and V-infinity tuned patched conic methods. A design analysis tool, based on the proposed method, is developed and tested in various orbiter mission scenarios.

  11. Jupiter Magnetospheric Orbiter and Trojan Asteroid Explorer in EJSM (Europa Jupiter System Mission) (United States)

    Sasaki, Sho; Fujimoto, Masaki; Takashima, Takeshi; Yano, Hajime; Kasaba, Yasumasa; Takahashi, Yukihiro; Kimura, Jun; Tsuda, Yuichi; Funase, Ryu; Mori, Osamu


    Europa Jupiter System Mission (EJSM) is an international mission to explore and Jupiter, its satellites and magnetospheric environment in 2020s. EJSM consists of (1) The Jupiter Europa Orbiter (JEO) by NASA, (2) the Jupiter Ganymede Orbiter (JGO) by ESA, and (3) the Jupiter Magnetospheric Orbiter (JMO) studied by JAXA (Japan Aerospace Exploration Agency). In February 2009, NASA and ESA decided to continue the study of EJSM as a candidate of the outer solar system mission. JMO will have magnetometers, low-energy plasma spectrometers, medium energy particle detectors, energetic particle detectors, electric field / plasma wave instruments, an ENA imager, an EUV spectrometer, and a dust detector. Collaborating with plasma instruments on board JEO and JGO, JMO will investigate the fast and huge rotating magnetosphere to clarify the energy procurement from Jovian rotation to the magnetosphere, to clarify the interaction between the solar wind the magnetosphere. Especially when JEO and JGO are orbiting around Europa and Ganymede, respectively, JMO will measure the outside condition in the Jovian magnetosphere. JMO will clarify the characteristics of the strongest accelerator in the solar system with the investigation of the role of Io as a source of heavy ions in the magnetosphere. JAXA started a study of a solar power sail for deep space explorations. Together with a solar sail (photon propulsion), it will have very efficient ion engines where electric power is produced solar panels within the sail. JAXA has already experienced ion engine in the successful Hayabusa mission, which was launched in 2003 and is still in operation in 2010. For the purpose of testing solar power sail technology, an engineering mission IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) will be launched in 2010 together with Venus Climate Orbiter PLANET-C. The shape of the IKAROS' membrane is square, with a diagonal distance of 20m. It is made of polyimide film only 0.0075mm

  12. Laser propulsion to earth orbit. Has its time come? (United States)

    Kantrowitz, Arthur


    Recent developments in high energy lasers, adaptive optics, and atmospheric transmission bring laser propulsion much closer to realization. Proposed here is a reference vehicle for study which consists of payload and solid propellant (e.g. ice). A suitable laser pulse is proposed for using a Laser Supported Detonation wave to produce thrust efficiently. It seems likely that a minimum system (10 Mw CO2 laser and 10 m dia. mirror) could be constructed for about $150 M. This minimum system could launch payloads of about 13 kg to a 400 km orbit every 10 minutes. The annual launch capability would be about 683 tons times the duty factor. Laser propulsion would be an order of magnitude cheaper than chemical rockets if the duty factor was 20 percent (10,000 launches/yr). Launches beyond that would be even cheaper. The chief problem which needs to be addressed before these possibilities could be realized is the design of a propellant to turn laser energy into thrust efficiently and to withstand the launch environment.

  13. The Swarm End-to-End mission simulator study: A demonstration of separating the various contributions to Earth's magnetic field using synthetic data

    DEFF Research Database (Denmark)

    Olsen, Nils; Haagmans, R.; Sabaka, T.J.


    Swarm, a satellite constellation to measure Earth's magnetic field with unpreceded accuracy, has been selected by ESA for launch in 2009. The mission will provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system by impro......Swarm, a satellite constellation to measure Earth's magnetic field with unpreceded accuracy, has been selected by ESA for launch in 2009. The mission will provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system...... by improving our understanding of the Earth's interior and climate. An End-to-End mission performance simulation was carried out during Phase A of the mission, with the aim of analyzing the key system requirements, particularly with respect to the number of Swarm satellites and their orbits related...... applied to the synthetic data to analyze various aspects of field recovery in relation to different number of satellites, different constellations and realistic noise sources. This paper gives an overview of the study activities, describes the generation of the synthetic data, and assesses the obtained...

  14. Tidal Heating of Earth-like Exoplanets around M Stars: Thermal, Magnetic, and Orbital Evolutions. (United States)

    Driscoll, P E; Barnes, R


    The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the "tidal zone," where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a viscoelastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within 0.07 AU circularize before 10 Gyr, independent of initial eccentricity. Once circular, these planets cool monotonically and maintain dynamos similar to that of Earth. Planets forced into eccentric orbits can experience a super-cooling of the core and rapid core solidification, inhibiting dynamo action for planets in the habitable zone. We find that tidal heating is insignificant in the habitable zone around 0.45 (or larger) solar-mass stars because tidal dissipation is a stronger function of orbital distance than stellar mass, and the habitable zone is farther from larger stars. Suppression of the planetary magnetic field exposes the atmosphere to stellar wind erosion and the surface to harmful radiation. In addition to weak magnetic fields, massive melt eruption rates and prolonged magma oceans may render eccentric planets in the habitable zone of low-mass stars inhospitable for life.

  15. Enabling Communication and Navigation Technologies for Future Near Earth Science Missions (United States)

    Israel, David J.; Heckler, Gregory; Menrad, Robert; Hudiburg, John; Boroson, Don; Robinson, Bryan; Cornwell, Donald


    In 2015, the Earth Regimes Network Evolution Study (ERNESt) proposed an architectural concept and technologies that evolve to enable space science and exploration missions out to the 2040 timeframe. The architectural concept evolves the current instantiations of the Near Earth Network and Space Network with new technologies to provide a global communication and navigation network that provides communication and navigation services to a wide range of space users in the near Earth domain. The technologies included High Rate Optical Communications, Optical Multiple Access (OMA), Delay Tolerant Networking (DTN), User Initiated Services (UIS), and advanced Position, Navigation, and Timing technology. This paper describes the key technologies and their current technology readiness levels. Examples of science missions that could be enabled by the technologies and the projected operational benefits of the architecture concept to missions are also described.

  16. On Directional Measurement Representation in Orbit Determination (United States)


    Precision Orbit Determination (OD) is often critical for successful satellite operations supporting a wide variety of missions. Directional or angles only...representations. The three techniques are then compared experimentally for a geostationary and a low Earth orbit satellite using simulated data to evaluate their... Orbit Determination (OD) is often critical for successful satellite operations supporting a wide variety of missions. Precision OD involves

  17. Possible Effect of the Earth's Inertial Induction on the Orbital Decay ...

    Indian Academy of Sciences (India)

    LAGEOS I and II are medium altitude satellites with nearly circular orbits. The motions of these satellites are accurately recorded and the past data of a few decades help to test many theories including the general theory of relativity. Therefore, it is hoped that the effect of the Earth's inertial induction can have any detectable ...

  18. Extension of Earth-Moon libration point orbits with solar sail propulsion

    NARCIS (Netherlands)

    Heiligers, M.J.; Macdonald, Malcolm; Parker, Jeffrey S.


    This paper presents families of libration point orbits in the Earth-Moon system that originate from complementing the classical circular restricted three-body problem with a solar sail. Through the use of a differential correction scheme in combination with a continuation on the solar sail

  19. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    DEFF Research Database (Denmark)

    Laundal, Karl M.; Finlay, Chris; Olsen, Nils


    analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting Swarm and CHAMP satellites, are used to co-estimate poloidal...

  20. Seeing Earth's Orbit in the Stars: Parallax and Aberration (United States)

    Timberlake, Todd K.


    During the 17th century the idea of an orbiting and rotating Earth became increasingly popular, but opponents of this view continued to point out that the theory had observable consequences that had never, in fact, been observed. Why, for instance, had astronomers failed to detect the annual parallax of the stars that "must" occur if…

  1. Desaturation Maneuvers and Precise Orbit Determination for the BepiColombo Mission

    CERN Document Server

    Alessi, Elisa Maria; Milani, Andrea; Tommei, Giacomo


    The purpose of this work is the analysis of the consequences that desaturation maneuvers can have in the precise orbit determination corresponding to the Radio Science Experiment (MORE) of the BepiColombo mission to Mercury. This mission is an ESA/JAXA joint project with very challenging objectives regarding geodesy, geophysics and fundamental physics. In the neighborhood of Mercury, the s/c will experience strong solar radiation pressure torques; the s/c attitude is controlled by inertial wheels that after some time reach their maximum rotation state. Then they have to be slowed down by means of thruster pulses, inducing a residual acceleration on the s/c, with a desaturation (or off-loading) maneuver. In this paper, we will show how such maneuvers affect the orbit of the s/c and the radio science measurements and, also, how to include them in the orbit determination and parameter estimation procedure. The non linear least squares fit we consider is applied on a set of observational arcs separated by interva...

  2. Spacecraft orbit lifetime within two binary near-Earth asteroid systems (United States)

    Damme, Friedrich; Hussmann, Hauke; Oberst, Jürgen


    We studied the motion of medium-sized and small spacecraft orbiting within the binary asteroid systems 175,706 (1996 FG3) and 65,803 Didymos (1996 GT). We have considered spacecraft motion within the binary systems distance regimes between 0.4 and 2.5 km for Didymos and 0.8-4 km for 1996 FG3. Orbital motion of spacecraft, beginning from 20,000 initial conditions lying in the orbital planes of the secondary, were simulated and evaluated for lifespan. The simulations include the effects of (1) the asteroid's mass, shape, and rotational parameters, (2) the secondary's mass and orbit parameters, (3) the spacecraft mass, surface area, and reflectivity (representing large box-wing-shaped medium-sized spacecraft as well as small satellites), and (4) the time of the mission, and therefore the relative position of the system to the sun. Stable orbital motion (i.e., not requiring thrusting maneuvers) was achieved using the Lagrange points L4/L5 and orbital resonances. This allows for long motion arcs, e.g. of 90 days (L4) and 35 days (resonance) in the Didymos system. The accuracy necessary to deploy a probe into L4, so it can remain there for 35 day, is evaluated by comparisons. Retrograde orbits were found assuring 90 days of low eccentric orbiting for a compact small satellite for a great variety of initial conditions. The comparison of simulations at aphelion and perihelion as well as the different spacecraft show the critical impact of solar radiation pressure on orbital stability. 65,803 Didymos (1996 GT) is shown to be more suitable for orbit phases at the close distances we studied compared to 175,706 (1996 FG3). Two possible obliquities of the Didymos system were considered to study the effects of the inclination on perturbing forces at equinox and solstice, showing that cases of low obliquity or times of equinox are beneficial for spacecraft orbiting.

  3. Marco Polo, a JAXA-ESA sample return mission to a Near-Earth Object (United States)

    Vernazza, P.


    Marco Polo is a sample return mission to a Near-Earth Object (NEO). It is proposed to be performed in collaboration between the European Space Agency (ESA) and the Japanese Space Agency (JAXA). Both JAXA and ESA are currently performing Phase-A studies for this mission; within ESA, the mission is studied as part of the Cosmic Vision 2015-2025 Programme. The main objective of the mission is to return unmodified material from a primitive NEO to the Earth to allow its accurate analysis in ground-based laboratories. These primitive NEOs are part of the small body population that represents the leftover building blocks of the Solar System formation process. They offer important clues to the chemical mixture from which the planets formed about 4.6 billion years ago and carry records both of the Solar System's birth and early phases. In addition, the mission will allow studying the geological evolution and physical properties of small bodies. Marco Polo will provide the first opportunity for detailed laboratory study of the most primitive materials that formed the terrestrial planets and advance our understanding of some of the fundamental issues in the origin and early evolution of the Solar System, the Earth and possibly life itself. Determining the physical properties of a NEO will also help assessing mitigation strategies for the impact risk of such an object on the Earth. This presentation will focus on the ESA side of the assessment study. The technical development status in Europe will be presented.

  4. Investigating On-Orbit Attitude Determination Anomalies for the Solar Dynamics Observatory Mission (United States)

    Vess, Melissa F.; Starin, Scott R.; Chia-Kuo, Alice Liu


    The Solar Dynamics Observatory (SDO) was launched on February 11, 2010 from Kennedy Space Center on an Atlas V launch vehicle into a geosynchronous transfer orbit. SDO carries a suite of three scientific instruments, whose observations are intended to promote a more complete understanding of the Sun and its effects on the Earth's environment. After a successful launch, separation, and initial Sun acquisition, the launch and flight operations teams dove into a commissioning campaign that included, among other things, checkout and calibration of the fine attitude sensors and checkout of the Kalman filter (KF) and the spacecraft s inertial pointing and science control modes. In addition, initial calibration of the science instruments was also accomplished. During that process of KF and controller checkout, several interesting observations were noticed and investigated. The SDO fine attitude sensors consist of one Adcole Digital Sun Sensor (DSS), two Galileo Avionica (GA) quaternion-output Star Trackers (STs), and three Kearfott Two-Axis Rate Assemblies (hereafter called inertial reference units, or IRUs). Initial checkout of the fine attitude sensors indicated that all sensors appeared to be functioning properly. Initial calibration maneuvers were planned and executed to update scale factors, drift rate biases, and alignments of the IRUs. After updating the IRU parameters, the KF was initialized and quickly reached convergence. Over the next few hours, it became apparent that there was an oscillation in the sensor residuals and the KF estimation of the IRU bias. A concentrated investigation ensued to determine the cause of the oscillations, their effect on mission requirements, and how to mitigate them. The ensuing analysis determined that the oscillations seen were, in fact, due to an oscillation in the IRU biases. The low frequencies of the oscillations passed through the KF, were well within the controller bandwidth, and therefore the spacecraft was actually

  5. Low-Thrust Transfer Design of Low-Observable Geostationary Earth Orbit Satellite

    Directory of Open Access Journals (Sweden)

    Bing Hua


    Full Text Available With radar and surface-to-air missiles posing an increasing threat to on-orbit spacecraft, low-observable satellites play an important role in low-thrust transfers. This paper presents the design for a low-thrust geostationary earth orbit (GEO transfer control strategy which takes into consideration the low-observable constraint and discusses Earth shadow and perturbation. A control parameter optimization addresses the orbit transfer problem, and five thrust modes are used. Simulation results show that the method outlined in this paper is simple and feasible and results in reduced transfer time with a small amount of calculation. The method therefore offers a useful reference for low-thrust GEO transfer design.

  6. Mission EarthFusing GLOBE with NASA Assets to Build SystemicInnovation in STEM Education (United States)

    Czajkowski, K. P.; Garik, P.; Padgett, D.; Darche, S.; Struble, J.; Adaktilou, N.


    Mission Earth is a project funded through the NASA CAN that is developing a systematic embedding of NASA assets that is being implemented by a partnership of organizations across the US. Mission Earth brings together scientists and science educators to develop a K-12 "Earth as a system" curriculum progression following research-based best practices. GLOBE and NASA assets will be infused into the curricula of schools along the K-12 continuum, leveraging existing partnerships and networks and supported through state departments of education and targeting underrepresented groups, as a systemic, effective, and sustainable approach to meeting NASA's science education objectives. This presentation will discuss plans for the Mission Earth project and successes and lessons learned in the first year. Mission Earth is developing curricular materials to support vertically integrated learning progressions. It develops models of professional development utilizing sustainable infrastructures. It will support STEM careers focusing on career technical education (CTE). And, it will engage undergraduate education majors through pre-service courses and engineering students through engineering challenges.

  7. The rotational motion of an earth orbiting gyroscope according to the Einstein theory of general relativity (United States)

    Hoots, F. R.; Fitzpatrick, P. M.


    The classical Poisson equations of rotational motion are used to study the attitude motions of an earth orbiting, rapidly spinning gyroscope perturbed by the effects of general relativity (Einstein theory). The center of mass of the gyroscope is assumed to move about a rotating oblate earth in an evolving elliptic orbit which includes all first-order oblateness effects produced by the earth. A method of averaging is used to obtain a transformation of variables, for the nonresonance case, which significantly simplifies the Poisson differential equations of motion of the gyroscope. Long-term solutions are obtained by an exact analytical integration of the simplified transformed equations. These solutions may be used to predict both the orientation of the gyroscope and the motion of its rotational angular momentum vector as viewed from its center of mass. The results are valid for all eccentricities and all inclinations not near the critical inclination.

  8. The Lunar Reconnaissance Orbiter Mission - Six years of science and exploration at the Moon (United States)

    Keller, J. W.; Petro, N. E.; Vondrak, R. R.


    Since entering lunar orbit on June 23, 2009 the Lunar Reconnaissance Orbiter (LRO) has made comprehensive measurements of the Moon and its environment. The seven LRO instruments use a variety of primarily remote sensing techniques to obtain a unique set of observations. These measurements provide new information regarding the physical properties of the lunar surface, the lunar environment, and the location of volatiles and other resources. Scientific interpretation of these observations improves our understanding of the geologic history of the Moon, its current state, and what its history can tell us about the evolution of the Solar System. Scientific results from LRO observations overturned existing paradigms and deepened our appreciation of the complex nature of our nearest neighbor. This paper summarizes the capabilities, measurements, and some of the science and exploration results of the first six years of the LRO mission.

  9. The Lunar Reconnaissance Orbiter Mission Six Years of Science and Exploration at the Moon (United States)

    Keller, J. W.; Petro, N. E.; Vondrak, R. R.


    Since entering lunar orbit on June 23, 2009 the Lunar Reconnaissance Orbiter (LRO) has made comprehensive measurements of the Moon and its environment. The seven LRO instruments use a variety of primarily remote sensing techniques to obtain a unique set of observations. These measurements provide new information regarding the physical properties of the lunar surface, the lunar environment, and the location of volatiles and other resources. Scientific interpretation of these observations improves our understanding of the geologic history of the Moon, its current state, and what its history can tell us about the evolution of the Solar System. Scientific results from LRO observations overturned existing paradigms and deepened our appreciation of the complex nature of our nearest neighbor. This paper summarizes the capabilities, measurements, and some of the science and exploration results of the first six years of the LRO mission.

  10. Orbital Transfer Vehicle (space taxi) with aerobraking at Earth and Mars (United States)


    This report shall cover all major aspects of the design of an Aeroassisted Manned Transfer Vehicle (or TAXI) for use as part of advanced manned Mars missions based on a cycling ship concept. Along with the heliocentric orbiting Cycling Spacecraft, such a TAXI would be a primary component of a long-term transportation system for Mars exploration. The Aeroassisted Manned Transfer Vehicle (AMTV) design developed shall operate along transfer trajectories between Earth and a Cycling Spacecraft (designed by the University of Michigan) and Mars. All operations of the AMTV shall be done primarily within the sphere of influence of the two planets. Maximum delta-V's for the vehicle have been established near 9 km/sec, with transfer durations of about 3 days. Acceleration deltaV's will be accomplished using 3 SSME-based hydrogen-oxygen chemical rockets (l(sub sp) = 485 sec & Thrust greater than = 300,00 Ib(sub f)/engine) with a thrust vector directly opposite the aerobraking deceleration vector. The aerobraking deceleration portion of an AMTV mission would be accomplished in this design by a moderate L/D aeroshield of an ellipsoidally-blunt, raked-off, elliptic cone (EBROEC) shape. The reusable thermal protection material comprising the shield will consist of a flexible, multi-layer, ceramic fabric stretched over a lightweight, rigid, shape - defining truss structure. Behind this truss, other components, including the engine supports, would be attached and protected from heating during aerobraking passes. Among these other components would be 2 LOX tanks and 4 LH2 tanks (and their support frames) holding over 670,000 lbm of propellant necessary to impart the required delta-V to the 98,000 lbm burnout mass vehicle. A 20,000 lbm crew module with docking port (oriented parallel to the accel./decel. axis) will provide accommodations for 9 crew members (11 under extreme conditions) for durations up to seven days, thus allowing extra time for emergency situations. This AMTV will be

  11. Ground Track Acquisition and Maintenance Maneuver Modeling for Low-Earth Orbit Satellite

    Directory of Open Access Journals (Sweden)

    Byoung-Sun Lee


    Full Text Available This paper presents a comprehensive analytical approach for determining key maneuver parameters associated with the acquisition and maintenance of the ground track for a low-earth orbit. A livearized model relating changes in the drift rate of the ground track directly to changes in the orbital semi-major axis is also developed. The effect of terrestrial atmospheric drag on the semi-major axis is also explored, being quantified through an analytical expression for the decay rate as a function of density. The non-singular Lagrange planetary equations, further simplified for nearly circular orbits, provide the desired relationships between the corrective in-plane impulsive velocity increments and the corresponding effects on the orbit elements. The resulting solution strategy offers excellent insight into the dynamics affecting the timing, magnitude, and frequency of these maneuvers. Simulations are executed for the ground track acquisition and maintenance maneuver as a pre-flight planning and analysis.

  12. TYCHO: Demonstrator and operational satellite mission to Earth-Moon-Libration point EML-4 for communication relay provision as a service (United States)

    Hornig, Andreas; Homeister, Maren


    In the current wake of mission plans to the Moon and to Earth-Moon Libration points (EML) by several agencies and organizations, TYCHO identifies the key role of telecommunication provision for the future path of lunar exploration. It demonstrates an interesting extension to existing communication methods to the Moon and beyond by combining innovative technology with a next frontier location and the commercial space communication sector. It is evident that all communication systems will rely on direct communication to Earth ground stations. In case of EML-2 missions around HALO orbits or bases on the far side of the Moon, it has to be extended by communication links via relay stations. The innovative approach is that TYCHO provides this relay communication to those out-of-sight lunar missions as a service. TYCHO will establish a new infrastructure for future missions and even create a new market for add-on relay services. The TMA-0 satellite is TYCHO's first phase and a proposed demonstrator mission to the Earth-Moon Libration point EML-4. It demonstrates relay services needed for automated exploratory and manned missions (Moon bases) on the rim (>90°E and >90°W) and far side surface, to lunar orbits and even to EML-2 halo orbits (satellites and space stations). Its main advantage is the permanent availability of communication coverage. This will provide full access to scientific and telemetry data and furthermore to crucial medical monitoring and safety. The communication subsystem is a platform for conventional communication but also a test-bed for optical communication with high data-rate LASER links to serve the future needs of manned bases and periodic burst data-transfer from lunar poles. The operational TMA-1 satellite is a stand-alone mission integrated into existing space communication networks to provide open communication service to external lunar missions. Therefore the long-time stable libration points EML-4 and -5 are selected to guarantee an

  13. Detection of Dark Electric Matter Objects Falling Out from Earth-Crossing Orbits (United States)

    Drobyshevski, E. M.


    If the DM consists of elementary Planckian black holes, their number (and flux) should be fairly low. If, however, they carry an electric charge corresponding to their mass (up to Ze ≈ 10e), such DArk Electric Matter Objects, daemons, should interact strongly with matter. They should be slowed down somewhat when crossing celestial bodies, build up in them, and in multiple systems, in close lying orbits too (e.g., in Earth-crossing orbits). Capture, say, of a Fe nucleus by a negative daemon releases >100 MeV of energy, i.e., cause ejection of ~10 nucleons. The detector consisting of two ZnS(Ag) scintillation screens stacked one upon the other (four modules 0.25 m2 each) detects at CL > 99% events with a time shift corresponding to velocities V ~ 30-5 km/s (in both down- and upward crossings). Such velocities are typical for objects trapped into helio- and geocentric orbits (with the latter crossing the Earth's surface to become finally confined to its interior). Of particular significance (> 3σ) is a group with V ≈ 10-15 km/s, which is characteristic of objects falling from near-Earth almost circular heliocentric orbits. Their flux is >10-9 cm-2s-1 and varies with P = 0.5 year.

  14. Detection of hypervelocity dust impacts on the Earth orbiting Cluster and MMS spacecraft and problems with signal interpretation (United States)

    Vaverka, Jakub; Pellinen-Wannberg, Asta; Kero, Johan; Mann, Ingrid; De Spiegeleer, Alexandre; Hamrin, Maria; Norberg, Carol; Pitkänen, Timo


    Detection of hypervelocity dust impacts on a spacecraft body by electric field instruments have been reported by several missions such as Voyager, WIND, Cassini, STEREO. The mechanism of this detection is still not completely understood and is under intensive laboratory investigation. A commonly accepted theory is based on re-collection of plasma cloud particles generated by a hypervelocity dust impact by a spacecraft surface and an electric field antenna resulting in a fast change in the potential of the spacecraft body and antenna. These changes can be detected as a short pulse measured by the electric field instrument. We present the first detection of dust impacts on the Earth-orbiting MMS and Cluster satellites. Each of the four MMS spacecraft provide probe-to-spacecraft potential measurements for their respective the six electric field antennas. This gives a unique view on signals generated by dust impacts and allow their reliable identification which is not possible for example on the Cluster spacecraft. We discuss various instrumental effects and solitary waves, commonly present in the Earth's magnetosphere, which can be easily misinterpreted as dust impacts. We show the influence of local plasma environment on dust impact detection for satellites crossing various regions of the Earth's magnetosphere where the concentration and the temperature of plasma particles change significantly.

  15. MMOD-IMLI: Integrated Thermal Insulation and Micrometeoroid/Orbital Debris Protection Project (United States)

    National Aeronautics and Space Administration — For NASA extended missions in Low Earth Orbit (LEO), Micrometeoroid and Orbital Debris (MMOD) protection for spacecraft, space stations and orbiting fuel depots is...

  16. Aircraft data collection in support of NASA's earth observing satellite missions (United States)

    NASA's Earth observing missions have been providing global information on soil moisture, vegetation, and precipitation that is crucial for hydrological and agricultural applications. For example, accurate soil moisture information is a key component in land surface and agricultural models used for w...

  17. HeMISE (Helio-Magnetism Investigation from the Sun to Earth): a twin spacecraft mission at the Sun-Earth Lagrangian points L4 and L5 (United States)

    Bemporad, Alessandro; Fineschi, Silvano; Focardi, Mauro; Landini, Federico; Romoli, Marco; Pancrazzi, Maurizio

    The Sun-Earth environment is a much more dynamic and eventful system than the common-life experience of looking at the sky can suggest and severe disturbances on the Earth magnetic field called geomagnetic storms often occur. These sudden disturbances can adversely affect the health of humans in space and in high altitude commercial flights. Further advancing in our forecasting capabilities of these storms will necessary requires a much deeper understanding of the origin on the Sun and propagation in the interplanetary medium of these disturbances. This means that we need a better understanding of how magnetic fields are generated in the solar interior, how their emergence through the photosphere, their storage and release in the lower corona, and the final connection with our planet: a mission specifically dedicated to this objective is needed. So far measurements of the solar magnetic field are mostly restricted to the low layers of the solar atmosphere. Extrapolation techniques underlying numerous assumptions are used to estimate the magnetic field in the transition region from the chromospheres to the corona and in the corona itself. More recently, ground-based spectropolarimetry has proven to be very useful to provide information of the coronal magnetic fields on the plane of the sky, but there are no spacecraft providing at the same time measurement of photospheric fields responsible for the coronal configuration. The solution will be offered by a multi-spacecraft mission designed to study at the same time photospheric and coronal magnetic fields and the interplanetary evolution of generated solar transients propagating along the Sun-Earth line. The HeMISE mission will investigate the emission and its polarization from the extreme ultraviolet to the white light wavelengths regimes. This will be done by 2 twin spacecraft, carrying remote sensing and in situ instruments, located in stable orbits around L4 and L5 Lagrangian points. Twin spacecraft with

  18. Earth Entry Vehicle Design for Sample Return Missions Using M-SAPE (United States)

    Samareh, Jamshid


    Most mission concepts that return sample material to Earth share one common element: an Earth entry vehicle (EEV). The primary focus of this paper is the examination of EEV design space for relevant sample return missions. Mission requirements for EEV concepts can be divided into three major groups: entry conditions (e.g., velocity and flight path angle), payload (e.g., mass, volume, and g-load limit), and vehicle characteristics (e.g., thermal protection system, structural topology, and landing concepts). The impacts of these requirements on the EEV design have been studied with an integrated system analysis tool, and the results will be discussed in details. In addition, through sensitivities analyses, critical design drivers that have been identified will be reviewed.

  19. Momentum Management for the NASA Near Earth Asteroid Scout Solar Sail Mission (United States)

    Heaton, Andrew; Diedrich, Benjamin L.; Orphee, Juan; Stiltner, Brandon; Becker, Christopher


    The Momentum Management (MM) system is described for the NASA Near Earth Asteroid Scout (NEA Scout) cubesat solar sail mission. Unlike many solar sail mission proposals that used solar torque as the primary or only attitude control system, NEA Scout uses small reaction wheels (RW) and a reaction control system (RCS) with cold gas thrusters, as described in the abstract "Solar Sail Attitude Control System for Near Earth Asteroid Scout Cubesat Mission." The reaction wheels allow fine pointing and higher rates with low mass actuators to meet the science, communication, and trajectory guidance requirements. The MM system keeps the speed of the wheels within their operating margins using a combination of solar torque and the RCS.

  20. Uranian ring orbits from earth-based and Voyager occultation observations (United States)

    French, Richard G.; Elliot, J. L.; French, Linda M.; Kangas, Julie A.; Meech, Karen J.


    A novel kinematical model of the Uranian rings has been derived from Voyager occultation timings and earth-based observations of the occultations of U23, U25, and U28, to yield an improved orbit solution that is accurate to about 1 km in the ring plane; this allows a critical comparison to be conducted between ring locations and suspected resonances. The gamma ring is noted to have a peculiar orbit that combines a precessing elliptical ring with a radially-oscillating normal mode. The kinematical model confirms the suspected association of resonances between the 1986U7 and 1986U8 satellites with some of the rings.

  1. Cassini's Ring Grazing and Grand Finale Orbits: Topping Off an Awesome Mission (United States)

    Edgington, Scott; Spilker, Linda; Coustenis, Athena


    The Cassini-Huygens mission, a joint collaboration between NASA, ESA, and the Italian Space Agency, is in its last year of operations after nearly 13 years in orbit around Saturn. Cassini will send back its final bits of unique data on September 15th, 2017 as it plunges into Saturn's atmosphere, vaporizing and satisfying planetary protection requirements. Before that time Cassini will continue its legacy of exploration and discovery in 2017 and return unique science data provided by orbits taking the spacecraft into unexplored regions near Saturn and its rings. From the new vantage points, Cassini will continue to study seasonal and temporal changes in the system as northern summer solstice approaches. With the exception of one remaining targeted Titan flyby, all of Cassini's close icy satellite flybys, including those of Enceladus, are now completed. In November 2016, Cassini transitioned to a series of orbits with peripases just outside Saturn's F ring. These 20 orbits include close flybys of some tiny ring moons and excellent views of the F ring and Saturn's outer A ring. The 126th and final close flyby of Titan will propel Cassini across Saturn's main rings and into its Grand Finale series of orbits. Cassini's Grand Finale, starting in April 2017, is comprised of 22 orbits at an inclination of 63 degrees. Cassini will repeatedly dive between Saturn's innermost rings and upper atmosphere providing insights into fundamental questions unattainable during the rest of the mission. Cassini will be the first spacecraft to explore this region. These close orbits provide the highest resolution observations of both the rings and Saturn, and direct in-situ sampling of the ring particles, composition, plasma, Saturn's exosphere and the innermost radiation belts. Saturn's gravitational field will be measured to unprecedented accuracy, providing information on the interior structure of the planet, winds in the outer layers of Saturn's atmosphere, and the mass distribution in

  2. Precision non-conservative force modelling for Low Earth Orbiting spacecraft


    Sibthorpe, Anthony John


    Low Earth Orbiting spacecraft are used in various ways for remote observation and measurement of system Earth some classes of measurements are only useful when modelled in a spatial reference frame. As the position of a satellite at a particular epoch is used to provide a fixed point of reference, it is vital that we know these positions both accurately and precisely. Non-conservative forces, which change the energy state of a spacecraft system, can have a dramatic effect on the estimated pos...

  3. Probes to the Inferior Planets - A New Dawn for NEO and IEO Detection Technology Demonstration from Heliocentric Orbits Interior to the Earth's? (United States)

    Grundmann, J. T.; Mottola, S.; Drentschew, M.; Drobczyk, M.; Kahle, R.; Maiwald, V.; Quantius, D.; Zabel, P.; Van Zoest, T.


    With the launch of MESSENGER and VENUS EXPRESS, a new wave of exploration of the inner solar system has begun. Noting the growing number of probes to the inner solar system, it is proposed to connect the expertise of the respective spacecraft teams and the NEO and IEO survey community to best utilize the extended cruise phases and to provide additional data return in support of pure science as well as planetary defence. Several missions to Venus and Mercury are planned to follow in this decade. Increased interest in the inferior planets is accompanied by several missions designed to study the Sun and the interplanetary medium (IPM) from a position near or in Earth orbit, such as the STEREO probes and SDO. These augment established solar observation capabilities at the Sun-Earth L1 Lagrangian point such as the SOHO spacecraft. Thus, three distinct classes of spacecraft operate or observe interior to Earth's orbit. All these spacecraft carry powerful multispectral cameras optimized for their respective primary targets. MESSENGER is scheduled to end its six-year interplanetary cruise in March 2011 to enter Mercury orbit, but a similarly extended cruise with several gravity-assists awaits the European Mercury mission BEPICOLOMBO. Unfortunately, the automatic abort of the orbit insertion manoeuvre has also left AKATSUKI (a.k.a. Venus Climate Orbiter (VCO), Planet-C) stranded in heliocentric orbit. After an unintended fly-by, the probe will catch up with Venus in approximately six years. Meanwhile, it stays mostly interior to Venus in a planet-leading orbit. In addition to the study of comets and their interaction with the IPM, observations of small bodies akin to those carried out by outer solar system probes are occasionally attempted with the equipment available. The study of structures in the interplanetary dust (IPD) cloud has been a science objective during the cruise phase of the Japanese Venus probe AKATSUKI from Earth to Venus. IPD observations in the

  4. Trade Study for Neutron Transport at Low Earth Orbit: Adding Fidelity to DIORAMA

    Energy Technology Data Exchange (ETDEWEB)

    McClanahan, Tucker Caden [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wakeford, Daniel Tyler [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    The Distributed Infrastructure Offering Real-Time Access to Modeling and Analysis (DIORAMA) software provides performance modeling capabilities of the United States Nuclear Detonation Detection System (USNDS) with a focus on the characterization of Space-Based Nuclear Detonation Detection (SNDD) instrument performance [1]. A case study was done to add the neutron propagation capabilities of DIORAMA to low earth orbit (LEO), and compare the back-calculated incident energy from the time-of- ight (TOF) spectrum with the scored incident energy spectrum. As the scoring altitude lowers, the time increase due to scattering takes up much more of the fraction of total TOF; whereas at geosynchronous earth orbit (GEO), the time increase due to scattering is a negligible fraction of the total TOF [2]. The scattering smears out the TOF enough to make the back-calculation of the initial energy spectrum from the TOF spectrum very convoluted.

  5. FLUKA Calculation of the Neutron Albedo Encountered at Low Earth Orbits

    CERN Document Server

    Claret, Arnaud; Combier, Natacha; Ferrari, Alfredo; Laurent, Philippe


    This paper presents Monte-Carlo simulations based on the Fluka code aiming to calculate the contribution of the neutron albedo at a given date and altitude above the Earth chosen by the user. The main input parameters of our model are the solar modulation affecting the spectra of cosmic rays, and the date of the Earth’s geomagnetic fi eld. The results consist in a two-parameter distribution, the neutron energy and the angle to the tangent plane of the sphere containing the orbi t of interest, and are provided by geographical position above the E arth at the chosen altitude. This model can be used to predict the te mporal variation of the neutron fl ux encountered along the orbit, and thus constrain the determination of the instrumental backg round noise of space experiments in low earth orbit.

  6. On the Tropical Rainfall Measuring Mission (TRMM): Bringing NASA's Earth System Science Program to the Classroom (United States)

    Shepherd, J. Marshall


    The Tropical Rainfall Measuring Mission is the first mission dedicated to measuring tropical and subtropical rainfall using a variety of remote sensing instrumentation, including the first spaceborne rain-measuring radar. Since the energy released when tropical rainfall occurs is a primary "fuel" supply for the weather and climate "engine"; improvements in computer models which predict future weather and climate states may depend on better measurements of global tropical rainfall and its energy. In support of the STANYS conference theme of Education and Space, this presentation focuses on one aspect of NASA's Earth Systems Science Program. We seek to present an overview of the TRMM mission. This overview will discuss the scientific motivation for TRMM, the TRMM instrument package, and recent images from tropical rainfall systems and hurricanes. The presentation also targets educational components of the TRMM mission in the areas of weather, mathematics, technology, and geography that can be used by secondary school/high school educators in the classroom.

  7. Precision non-conservative force modelling for Low Earth Orbiting spacecraft (United States)

    Sibthorpe, Anthony John


    Low Earth Orbiting spacecraft are used in various ways for remote observation and measurement of system Earth some classes of measurements are only useful when modelled in a spatial reference frame. As the position of a satellite at a particular epoch is used to provide a fixed point of reference, it is vital that we know these positions both accurately and precisely. Non-conservative forces, which change the energy state of a spacecraft system, can have a dramatic effect on the estimated position of a satellite if unmodelled or, as is often the case, are modelled only crudely. Downstream Earth observation data can inherit significant errors as a result. As an example of this, it has been recognised that apparent long wavelength signals can be introduced into interferometric synthetic aperture radar (SAR) images by orbit error. Such images are used to monitor surface deformation, and may provide an indication of strain accumulation as a pre-cursor to Earthquake activity. It makes sense therefore to better model these non-conservative forces, thus improving the quality of the Earth observation data. This project develops precise methodologies for modelling of solar radiation pressure / thermal re-radiation / eclipse modelling / Earth radiation pressure / spacecraft internal heat distribution / on-board instrument power output, and applies these techniques to the European Space Agency's ENVISAT satellite. This complicated satellite has necessitated the development of a significant number of new algorithms for dealing with a large number of geometric primitives. A graphical display tool, developed during this research, allows rapid model development and improved error checking. Resultant models are incorporated into the GEODYN II orbit determination software, developed at NASA's Goddard Space Flight Centre. Precise orbits computed using tracking data in combination with the newly developed force models are compared against precise orbits generated using nominal force

  8. Halo orbit transfer trajectory design using invariant manifold in the Sun-Earth system accounting radiation pressure and oblateness (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kushvah, Badam Singh


    In this paper, we study the invariant manifold and its application in transfer trajectory problem from a low Earth parking orbit to the Sun-Earth L1 and L2-halo orbits with the inclusion of radiation pressure and oblateness. Invariant manifold of the halo orbit provides a natural entrance to travel the spacecraft in the solar system along some specific paths due to its strong hyperbolic character. In this regard, the halo orbits near both collinear Lagrangian points are computed first. The manifold's approximation near the nominal halo orbit is computed using the eigenvectors of the monodromy matrix. The obtained local approximation provides globalization of the manifold by applying backward time propagation to the governing equations of motion. The desired transfer trajectory well suited for the transfer is explored by looking at a possible intersection between the Earth's parking orbit of the spacecraft and the manifold.

  9. Econometric comparisons of liquid rocket engines for dual-fuel advanced earth-to-orbit shuttles (United States)

    Martin, J. A.


    Econometric analyses of advanced Earth-to-orbit vehicles indicate that there are economic benefits from development of new vehicles beyond the space shuttle as traffic increases. Vehicle studies indicate the advantage of the dual-fuel propulsion in single-stage vehicles. This paper shows the economic effect of incorporating dual-fuel propulsion in advanced vehicles. Several dual-fuel propulsion systems are compared to a baseline hydrogen and oxygen system.

  10. Preliminary design and analysis of large delta wings for earth-to-orbit transports (United States)

    Lemessurier, R. W.; Bailey, J. P.; Macconochie, I. O.


    Two studies are described in which CAD methods are used for preliminary design of advanced earth-to-orbit transport wings. The first structural concept was a multilayer honeycomb wing composed of diffusion-bonded Inconel 718; the second concept (in which structural simplicity was sought) involved a honeycomb sandwich wing, for which only a leading edge and trailing edge spar were used. Some new technologies applicable to advanced wing designs are briefly discussed.

  11. Technology Readiness Level Assessment Process as Applied to NASA Earth Science Missions (United States)

    Leete, Stephen J.; Romero, Raul A.; Dempsey, James A.; Carey, John P.; Cline, Helmut P.; Lively, Carey F.


    Technology assessments of fourteen science instruments were conducted within NASA using the NASA Technology Readiness Level (TRL) Metric. The instruments were part of three NASA Earth Science Decadal Survey missions in pre-formulation. The Earth Systematic Missions Program (ESMP) Systems Engineering Working Group (SEWG), composed of members of three NASA Centers, provided a newly modified electronic workbook to be completed, with instructions. Each instrument development team performed an internal assessment of its technology status, prepared an overview of its instrument, and completed the workbook with the results of its assessment. A team from the ESMP SEWG met with each instrument team and provided feedback. The instrument teams then reported through the Program Scientist for their respective missions to NASA's Earth Science Division (ESD) on technology readiness, taking the SEWG input into account. The instruments were found to have a range of TRL from 4 to 7. Lessons Learned are presented; however, due to the competition-sensitive nature of the assessments, the results for specific missions are not presented. The assessments were generally successful, and produced useful results for the agency. The SEWG team identified a number of potential improvements to the process. Particular focus was on ensuring traceability to guiding NASA documents, including the NASA Systems Engineering Handbook. The TRL Workbook has been substantially modified, and the revised workbook is described.

  12. Prevalence of Earth-size Planets Orbiting Sun-like Stars (United States)

    Petigura, Erik Ardeshir


    In this thesis, I explore two topics in exoplanet science. The first is the prevalence of Earth-size planets in the Milky Way Galaxy. To determine the occurrence of planets having different sizes, orbital periods, and other properties, I conducted a survey of extrasolar planets using data collected by NASA's Kepler Space Telescope. This project involved writing new algorithms to analyze Kepler data, finding planets, and conducting follow-up work using ground-based telescopes. I found that most stars have at least one planet at or within Earth's orbit and that 26% of Sun-like stars have an Earth-size planet with an orbital period of 100 days or less. The second topic is the connection between the properties of planets and their host stars. The precise characterization of exoplanet hosts helps to bring planet properties like mass, size, and equilibrium temperature into sharper focus and probes the physical processes that form planets. I studied the abundance of carbon and oxygen in over 1000 nearby stars using optical spectra taken by the California Planet Search. I found a large range in the relative abundance of carbon and oxygen in this sample, including a handful of carbon-rich stars. I also developed a new technique called SpecMatch for extracting fundamental stellar parameters from optical spectra. SpecMatch is particularly applicable to the relatively faint planet-hosting stars discovered by Kepler.

  13. Minimum fuel round trip from a $L_2$ Earth-Moon Halo orbit to Asteroid 2006 RH$_{120}$


    Chyba, Monique; Haberkorn, Thomas; Jedicke, Robert


    International audience; The goal of this paper is to design a spacecraft round trip transfer from a parking orbit to Asteroid 2006\\;RH$_{120}$, during its capture time by Earth's gravity, while maximizing the final mass or equivalently minimizing the delta-v. The parking orbit is chosen as a Halo orbit around the Earth-Moon $L_2$ libration point. The round-trip transfer is composed of three portions: a rendezvous transfer departing from the parking orbit to reach 2006\\;RH$_{120}$, a lock-in p...

  14. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    CERN Document Server

    Laundal, Karl M; Olsen, Nils


    Interaction between the solar wind and the Earth's magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly linked, but their global behaviors are rarely analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting $\\textit{Swarm}$ and CHAMP satellites, are used to co-estimate poloidal and toroidal parts of the magnetic disturbance field, represented in magnetic apex coordinates. The use of apex coordinates reduces effects of longitudinal and hemispheric variations in the Earth's main field. We present global currents from both hemispheres during different sunlight conditions. The results show that the Birkeland currents vary with the conductivity, which depends most strongly on solar EUV ...

  15. The General Mission Analysis Tool (GMAT): A New Resource for Supporting Debris Orbit Determination, Tracking and Analysis (United States)

    Jah, Moriba; Huges, Steven; Wilkins, Matthew; Kelecy, Tom


    The General Mission Analysis Tool (GMAT) was initially developed at NASA's Goddard Space Flight Center (GSFC) as a high accuracy orbital analysis tool to support a variety of space missions. A formal agreement has recently been established between NASA and the Air Force Research Laboratory (AFRL) to further develop GMAT to include orbit determination (OD) capabilities. A variety of estimation strategies and dynamic models will be included in the new version of GMAT. GMAT will accommodate orbit determination, tracking and analysis of orbital debris through a combination of model, processing and implementation requirements. The GMAT processing architecture natively supports parallel processing such that allow it can efficiently accommodate the OD and tracking of numerous objects resulting from breakups. A full first release of the augmented GMAT capability is anticipated in September 2009 and it will be available for community use at no charge.

  16. Distributed Space Mission Design for Earth Observation Using Model-Based Performance Evaluation (United States)

    Nag, Sreeja; LeMoigne-Stewart, Jacqueline; Cervantes, Ben; DeWeck, Oliver


    Distributed Space Missions (DSMs) are gaining momentum in their application to earth observation missions owing to their unique ability to increase observation sampling in multiple dimensions. DSM design is a complex problem with many design variables, multiple objectives determining performance and cost and emergent, often unexpected, behaviors. There are very few open-access tools available to explore the tradespace of variables, minimize cost and maximize performance for pre-defined science goals, and therefore select the most optimal design. This paper presents a software tool that can multiple DSM architectures based on pre-defined design variable ranges and size those architectures in terms of predefined science and cost metrics. The tool will help a user select Pareto optimal DSM designs based on design of experiments techniques. The tool will be applied to some earth observation examples to demonstrate its applicability in making some key decisions between different performance metrics and cost metrics early in the design lifecycle.

  17. Conceptual study of Earth observation missions with a space-borne laser scanner (United States)

    Kobayashi, Takashi; Sato, Yohei; Yamakawa, Shiro


    The Japan Aerospace Exploration Agency (JAXA) has started a conceptual study of earth observation missions with a space-borne laser scanner (GLS, as Global Laser Scanner). Laser scanners are systems which transmit intense pulsed laser light to the ground from an airplane or a satellite, receive the scattered light, and measure the distance to the surface from the round-trip delay time of the pulse. With scanning mechanisms, GLS can obtain high-accuracy three-dimensional (3D) information from all over the world. High-accuracy 3D information is quite useful in various areas. Currently, following applications are considered. 1. Observation of tree heights to estimate the biomass quantity. 2. Making the global elevation map with high resolution. 3. Observation of ice-sheets. This paper aims at reporting the present state of our conceptual study of the GLS. A prospective performance of the GLS for earth observation missions mentioned above.

  18. Nuclear Electric Propulsion mission operations. (United States)

    Prickett, W. Z.; Spera, R. J.


    Mission operations are presented for comet rendezvous and outer planet exploration missions conducted by unmanned Nuclear Electric Propulsion (NEP) system employing in-core thermionic reactors for electric power generation. The selected reference mission are Comet Halley rendezvous and a Jupiter orbiter at 5.9 planet radii, the orbit of the moon Io. Mission operations and options are defined from spacecraft assembly through mission completion. Pre-launch operations and related GSE requirements are identified. Shuttle launch and subsequent injection to earth escape by the Centaur d-1T are discussed, as well as power plant startup and heliocentric mission phases.

  19. Science of Marco Polo : Near-Earth Object Sample Return Mission (United States)

    Barucci, M. A.; Yoshikawa, Makoto; Koschny, Detlef; Boehnhardt, Hermann; Brucato, J. Robert; Coradini, Marcello; Dotto, Elisabetta; Franchi, Ian A.; Green, Simon F.; Josset, Jean-Luc; Michel, Patrick; Kawagushi, Jun; Muinonen, Karri; Oberst, Juergen; Yano, Hajime; Binzel, Richard P.

    MARCO POLO is a joint European-Japanese sample return mission to a Near-Earth Object (NEO), selected by ESA in the framework of COSMIC VISION for an assessment study. This Euro-Asian mission will go to a primitive NEO, such as C or D type, scientifically characterize it at multiple scales, and bring samples back to Earth for detailed scientific investigation. NEOs are part of the small body population in the solar system, which are leftover building blocks of the solar system formation process. They offer important clues to the chemical mixture from which planets formed about 4.6 billion years ago. The scientific objectives of Marco Polo will therefore contribute to a better understanding of the origin and evolution of the Solar System, the Earth, and possibly Life itself. Marco Polo is based on a launch with a Soyuz Fregat and consists of a Mother Spacecraft (MSC), possibly carrying a lander. The MSC would approach the target asteroid and spend a few months for global characterization of the target to select a sampling site. Then, the MSC would then descend to retrieve, using a "touch and go" manoeuvre, several samples which will be transferred to a Sample Return Capsule (SRC). The MSC would return to Earth and release the SRC into the atmosphere for ground recovery. The sample of the NEO will then be available for detailed investigation in ground-based laboratories. The scientific objectives addressed by the mission and the current status of the mission study (ESA-JAXA) will be presented and discussed.

  20. Aerobraking strategies for the sample of comet coma earth return mission (United States)

    Abe, Takashi; Kawaguchi, Jun'ichiro; Uesugi, Kuninori; Yen, Chen-Wan L.

    The results of a study to the validate the applicability of the aerobraking concept to the SOCCER (sample of comet coma earth return) mission using a six-DOF computer simulation of the aerobraking process are presented. The SOCCER spacecraft and the aerobraking scenario and power supply problem are briefly described. Results are presented for the spin effect, payload exposure problem, and sun angle effect.

  1. A Comprehensive Structural Dynamic Analysis Approach for Multi Mission Earth Entry Vehicle (MMEEV) Development (United States)

    Perino, Scott; Bayandor, Javid; Siddens, Aaron


    The anticipated NASA Mars Sample Return Mission (MSR) requires a simple and reliable method in which to return collected Martian samples back to earth for scientific analysis. The Multi-Mission Earth Entry Vehicle (MMEEV) is NASA's proposed solution to this MSR requirement. Key aspects of the MMEEV are its reliable and passive operation, energy absorbing foam-composite structure, and modular impact sphere (IS) design. To aid in the development of an EEV design that can be modified for various missions requirements, two fully parametric finite element models were developed. The first model was developed in an explicit finite element code and was designed to evaluate the impact response of the vehicle and payload during the final stage of the vehicle's return to earth. The second model was developed in an explicit code and was designed to evaluate the static and dynamic structural response of the vehicle during launch and reentry. In contrast to most other FE models, built through a Graphical User Interface (GUI) pre-processor, the current model was developed using a coding technique that allows the analyst to quickly change nearly all aspects of the model including: geometric dimensions, material properties, load and boundary conditions, mesh properties, and analysis controls. Using the developed design tool, a full range of proposed designs can quickly be analyzed numerically and thus the design trade space for the EEV can be fully understood. An engineer can then quickly reach the best design for a specific mission and also adapt and optimize the general design for different missions.

  2. Polarization modulators based on liquid crystal variable retarders for the Solar Orbiter mission (United States)

    Alvarez-Herrero, A.; García Parejo, P.; Laguna, H.; Villanueva, J.; Barandiarán, J.; Bastide, L.; Reina, M.; Sánchez, A.; Gonzalo, A.; Navarro, R.; Vera, I.; Royo, M.


    A polarization modulator based on Liquid Crystal Variable Retarders (LCVRs) will be used in the Polarimetric and Helioseismic Imager (PHI) for the Solar Orbiter mission to measure the complete Stokes vector of the incoming light. PHI is one of the six remote sensing instruments onboard of this space mission led by the European Space Agency (ESA) with strong NASA participation. It is an imaging spectro-polarimeter that will acquire high resolution solar magnetograms. Also the LCVRs will be used in the polarization modulator of the METIS instrument (Multi Element Telescope for Imaging and Spectroscopy). METIS is a solar coronagraph that will analyze the linear polarization for observations of the visible-light K-corona. The polarization modulators are described in this work including the optical, mechanical, thermal and electrical aspects. Both modulators will consist of two identical LCVRs with a relative azimuth orientation of 45º for PHI and parallel for the METIS modulator. In the first case, the configuration allows the analysis of the full Stokes vector with maximum polarimetric efficiencies. In the second setup, wide acceptance angles (measured and analyzed including polarimetric efficiencies, wavefront error transmission, beam deviation and transmittance. This valuable information will allow to consolidate the detailed design of these devices increasing its TRL to 6 and to proceed to the manufacturing of the Qualification Model (QM) and Flight Models (FM).

  3. DESDynI - A NASA Mission for Ecosystems, Solid Earth, and Cryosphere Science (United States)

    Freeman, A.; Rosen, P.; Jordan, R.; Johnson, WTK.; Hensley, S.; Sweetser, T.; Loverro, A.; Smith, J.; Sprague, G.; Shen, Y.


    The National Research Council's Decadal Survey for Earth Science [1] identified the Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI) mission among the highest priorities for new NASA Earth missions. DESDynI consists of an L-band Synthetic Aperture Radar configured for repeat-pass interferometric observations (InSAR), and a nadir pointing lidar suitable for vegetation canopy structure characterization. DESDynI addresses many of the scientific objectives assigned high priority by the decadal survey. It will measure the height and structure of forests, changes in carbon storage in vegetation, ice sheet deformation and dynamics, and changes in Earth's surface and the movement of magma. These measurements will improve our understanding of the affects of changing climate and land use on species habitats and atmospheric CO2. DESDynI measurements will also facilitate the monitoring of species habitats, understanding the response of ice sheets to climate change and the impact on sea level, and forecasting the likelihood of earthquakes, volcanic eruptions, and landslides. Analyses are underway to evaluate efficient combinations of science objectives and mission/instrument scenarios. This paper will focus on the InSAR technology and observational trades that affect the science return, together with and separately from the lidar.


    Energy Technology Data Exchange (ETDEWEB)

    Thirouin, A.; Moskovitz, N.; Burt, B. [Lowell Observatory, 1400 W Mars Hill Rd, Flagstaff, AZ 86001 (United States); Binzel, R. P.; DeMeo, F. E.; Person, M. J. [Massachusetts Institute of Technology (MIT), 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Christensen, E. [University of Arizona, Tucson, AZ (United States); Polishook, D. [Department of Earth and Planetary Science, Weizmann Institute, Herzl St 234, Rehovot, 7610001 (Israel); Thomas, C. A. [Planetary Science Institute (PSI), 1700 E Fort Lowell Road 106, Tucson, AZ 85719 (United States); Trilling, D.; Hinkle, M.; Avner, D. [Department of Physics and Astronomy, P.O. Box 6010, Northern Arizona University, Flagstaff AZ 86001 (United States); Willman, M. [University of Hawaii, Pukalani, HI 96788 (United States); Aceituno, F. J., E-mail: [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía, S/N, Granada, E-18008 (Spain)


    The Mission Accessible Near-Earth Objects Survey aims to physically characterize sub-km near-Earth objects (NEOs). We report the first photometric results from the survey that began in 2013 August. Photometric observations were performed using 1–4 m class telescopes around the world. We present rotational periods and light curve amplitudes for 86 sub-km NEOs, though in some cases only lower limits are provided. Our main goal is to obtain light curves for small NEOs (typically, sub-km objects) and estimate their rotational periods, light curve amplitudes, and shapes. These properties are used for a statistical study to constrain overall properties of the NEO population. A weak correlation seems to indicate that smaller objects are more spherical than larger ones. We also report seven NEOs that are fully characterized (light curve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are objects fully characterized, with Δ v {sup NHATS} ≤ 12 km s{sup −1}, and a rotational period P  > 1 hr. Assuming a similar rate of object characterization as reported in this paper, approximately 1230 NEOs need to be characterized in order to find 100 viable mission targets.

  5. Solar Sail Attitude Control System for the NASA Near Earth Asteroid Scout Mission (United States)

    Orphee, Juan; Diedrich, Ben; Stiltner, Brandon; Becker, Chris; Heaton, Andrew


    An Attitude Control System (ACS) has been developed for the NASA Near Earth Asteroid (NEA) Scout mission. The NEA Scout spacecraft is a 6U cubesat with an eighty-six square meter solar sail for primary propulsion that will launch as a secondary payload on the Space Launch System (SLS) Exploration Mission 1 (EM-1) and rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Active Mass Translator (AMT) system. The reaction wheels allow fine pointing and higher rates with low mass actuators to meet the science, communication, and trajectory guidance requirements. The Momentum Management System (MMS) keeps the speed of the wheels within their operating margins using a combination of solar torque and the RCS. The AMT is used to adjust the sign and magnitude of the solar torque to manage pitch and yaw momentum. The RCS is used for initial de-tumble, performing a Trajectory Correction Maneuver (TCM), and performing momentum management about the roll axis. The NEA Scout ACS is able to meet all mission requirements including attitude hold, slews, pointing for optical navigation and pointing for science with margin and including flexible body effects. Here we discuss the challenges and solutions of meeting NEA Scout mission requirements for the ACS design, and present a novel implementation of managing the spacecraft Center of Mass (CM) to trim the solar sail disturbance torque. The ACS we have developed has an applicability to a range of potential missions and does so in a much smaller volume than is traditional for deep space missions beyond Earth.

  6. The mass of the super-Earth orbiting the brightest Kepler planet hosting star (United States)

    Lopez-Morales, Mercedes; HARPS-N Team


    HD 179070, aka Kepler-21, is a V = 8.25 oscillating F6IV star and the brightest exoplanet host discovered by Kepler. An early analysis of the Q0 - Q5 Kepler light curves by Howell et al. (2012) revealed transits of a planetary companion, Kepler-21b, with a radius of 1.6 R_Earth and an orbital period of 2.7857 days. However, they could not determine the mass of the planet from the initial radial velocity observations with Keck-HIRES, and were only able to impose a 2s upper limit of about 10 M_Earth. Here we present 82 new radial velocity observations of this system obtained with the HARPS-N spectrograph. We detect the Doppler shift signal of Kepler-21b at the 3.6s level, and measure a planetary mass of 5.9 ± 1.6 M_Earth. We also update the radius of the planet to 1.65 ± 0.08 R_Earth, using the now available Kepler Q0 - Q17 photometry for this target. The mass of Kepler-21b appears to fall on the apparent dividing line between super-Earths that have lost all the material in their outer layers and those that have retained a significant amount of volatiles. Based on our results Kepler-21b belongs to the first group. Acknowledgement: This work was supported by funding from the NASA XRP Program and the John Templeton Foundation.

  7. NASA's Asteroid Redirect Mission (ARM) (United States)

    Abell, P. A.; Mazanek, D. D.; Reeves, D. M.; Chodas, P. W.; Gates, M. M.; Johnson, L. N.; Ticker, R. L.


    Mission Description and Objectives: NASA's Asteroid Redirect Mission (ARM) consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), a robotic mission to visit a large (greater than approximately 100 meters diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will explore and investigate the boulder and return to Earth with samples. The ARRM is currently planned to launch at the end of 2021 and the ARCM is scheduled for late 2026.

  8. Overview of NASA Earth Observing Systems Terra and Aqua Moderate Resolution Imaging Spectroradiometer Instrument Calibration Algorithms and On-Orbit Performance (United States)

    Xiong, Xiaoxiong; Wenny, Brian N.; Barnes, William L.


    Since launch, the Terra and Aqua moderate resolution imaging spectroradiometer (MODIS) instruments have successfully operated on-orbit for more than 9 and 6.5 years, respectively. Iv1ODIS, a key instrument for the NASA's Earth Observing System (EOS) missions, was designed to make continuous observations for studies of Earth's land, ocean, and atmospheric properties and to extend existing data records from heritage earth-observing sensors. In addition to frequent global coverage, MODIS observations are made in 36 spectral bands, covering both solar reflective and thermal emissive spectral regions. Nearly 40 data products are routinely generated from MODIS' observations and publicly distributed for a broad range of applications. Both instruments have produced an unprecedented amount of data in support of the science community. As a general reference for understanding sensor operation and calibration, and thus science data quality, we ;provide an overview of the MODIS instruments and their pre-launch calibration and characterization, and describe their on-orbit calibration algorithms and performance. On-orbit results from both Terra and Aqua MODIS radiometric, spectral, and "spatial calibration are discussed. Currently, both instruments, including their on-board calibration devices, are healthy and are expected to continue operation for several }rears to come.

  9. High resolution earth observation from geostationary orbit by optical aperture synthesys (United States)

    Mesrine, M.; Thomas, E.; Garin, S.; Blanc, P.; Alis, C.; Cassaing, F.; Laubier, D.


    In this paper, we describe Optical Aperture Synthesis (OAS) imaging instrument concepts studied by Alcatel Alenia Space under a CNES R&T contract in term of technical feasibility. First, the methodology to select the aperture configuration is proposed, based on the definition and quantification of image quality criteria adapted to an OAS instrument for direct imaging of extended objects. The following section presents, for each interferometer type (Michelson and Fizeau), the corresponding optical configurations compatible with a large field of view from GEO orbit. These optical concepts take into account the constraints imposed by the foreseen resolution and the implementation of the co-phasing functions. The fourth section is dedicated to the analysis of the co-phasing methodologies, from the configuration deployment to the fine stabilization during observation. Finally, we present a trade-off analysis allowing to select the concept wrt mission specification and constraints related to instrument accommodation under launcher shroud and in-orbit deployment.

  10. Development of Electric Field Investigations for Future Missions in Japan: from Mercury, through Earth, toward Jupiter (United States)

    Kasaba, Yasumasa

    The electric field from DC to several 10s MHz is important for the clarification of global plasma dynamics, energetic processes, and wave-particle interactions in the planetary Magnetospheres by in-situ and remote sensing studies. We have developped the instruments for several missions, i.e., (1) BepiColombo Mercury Mag-netospheric Orbiter (MMO) to Mercury [just in FM development], (2) the small-sized radiation belt mission, ERG (Energization and Radiation in Geospace) [in EM design], (3) the cross-scale formation flight mission, SCOPE [in ceonceptual design], and (4) the future Jovian mission, EJSM, including JAXA Jupiter Magnetospheric Orbiter (JMO) and other elementss [in con-ceptual design]. Those will prevail the universal plasma mechanism and processes in the space laboratory. The common purposes of electric field, plasma waves, and radio waves observa-tion in those missions are: (a) Examination of the theories of high-energy particle acceleration by plasma waves, (b) identification of the origin of electric fields in the magnetosphere asso-ciated with cross-scale coupling processes, (c) diagnosis of plasma density, temperature and composition, and (d) investigation of wave-particle interaction and mode conversion processes. In order to achieve those objectives, the instrument including rigid antenna, wire antenna, and integrated receiver systems are now in development. Some of them were already used on the sounding rocket experiments (S310-23 launched by ISAS/JAXA) in 2007, and will also be used soon. As the applications of those development, we also try to adopt them to the space interferometer and the radar sounder. In this paper, we will summarize the current plan and efforts for those future activities.

  11. A review of the US Global Change Research Program and NASA's Mission to Planet Earth/Earth Observing System (United States)

    Moore, Berrien, III; Anderson, James G.; Costanza, Robert; Gates, W. Lawrence; Grew, Priscilla C.; Leinen, Margaret S.; Mayewski, Paul A.; McCarthy, James J.; Sellers, Piers J.


    This report reflects the results of a ten-day workshop convened at the Scripps Institution of Oceanography July 19-28, 1995. The workshop was convened as the first phase of a two part review of the U.S. Global Change Research Program (USGCRP). The workshop was organized to provide a review of the scientific foundations and progress to date in the USGCRP and an assessment of the implications of new scientific insights for future USGCRP and Mission to Planet Earth/Earth Observing System (MTPE/EOS) activities; a review of the role of NASA's MTPE/EOS program in the USGCRP observational strategy; a review of the EOS Data and Information System (EOSDIS) as a component of USGCRP data management activities; and an assessment of whether recent developments in the following areas lead to a need to readjust MTPE/EOS plans. Specific consideration was given to: proposed convergence of U.S. environmental satellite systems and programs, evolving international plans for Earth observation systems, advances in technology, and potential expansion of the role of the private sector. The present report summarizes the findings and recommendations developed by the Committee on Global Change Research on the basis of the presentations, background materials, working group deliberations, and plenary discussions of the workshop. In addition, the appendices include summaries prepared by the six working groups convened in the course of the workshop.


    Energy Technology Data Exchange (ETDEWEB)

    Fossati, L.; Haswell, C. A.; Patel, M. R.; Busuttil, R. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Bagnulo, S. [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom); Kowalski, P. M. [GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam (Germany); Shulyak, D. V. [Institute of Astrophysics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Sterzik, M. F., E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [European Southern Observatory, Casilla 19001, Santiago 19 (Chile)


    Since there are several ways planets can survive the giant phase of the host star, we examine the habitability and detection of planets orbiting white dwarfs. As a white dwarf cools from 6000 K to 4000 K, a planet orbiting at 0.01 AU would remain in the continuous habitable zone (CHZ) for {approx}8 Gyr. We show that photosynthetic processes can be sustained on such planets. The DNA-weighted UV radiation dose for an Earth-like planet in the CHZ is less than the maxima encountered on Earth, and hence non-magnetic white dwarfs are compatible with the persistence of complex life. Polarization due to a terrestrial planet in the CHZ of a cool white dwarf (CWD) is 10{sup 2} (10{sup 4}) times larger than it would be in the habitable zone of a typical M-dwarf (Sun-like star). Polarimetry is thus a viable way to detect close-in rocky planets around white dwarfs. Multi-band polarimetry would also allow us to reveal the presence of a planet atmosphere, providing a first characterization. Planets in the CHZ of a 0.6 M{sub Sun} white dwarf will be distorted by Roche geometry, and a Kepler-11d analog would overfill its Roche lobe. With current facilities a super-Earth-sized atmosphereless planet is detectable with polarimetry around the brightest known CWD. Planned future facilities render smaller planets detectable, in particular by increasing the instrumental sensitivity in the blue.

  13. MARCO POLO: A Near Earth Object Sample Return Mission in the ESA program Cosmic Vision 2015-2025 (United States)

    Dotto, Elisabetta; Barucci, M. A.; Yoshikawa, M.; Koschny, D.; Boehnhardt, H.; Brucato, J. R.; Coradini, M.; Franchi, I. A.; Green, S. F.; Josset, J. L.; Kawaguchi, J.; Michel, P.; Muinonen, K.; Oberst, J.; Yano, H.; Binzel, R. P.


    Marco Polo is a sample return mission to a Near Earth Object. In October 2007 this mission passed the first evaluation process in the framework of the ESA Cosmic Vision 2015-2025 context. The primary objectives of this mission is to visit a primitive NEO, to characterize it at multiple scales, and to bring samples back to Earth. Marco Polo will give us the first opportunity for detailed laboratory study of the most primitive materials that formed the planets. This will allow us to improve our knowledge of the processes which governed the origin and early evolution of the Solar System, and possibly of life on Earth.

  14. A dynamics and control algorithm for low Earth orbit precision formation flying satellites (United States)

    Eyer, Jesse Koovik

    An innovative dynamics and control algorithm is developed for a dual-nanosatellite formation flying mission. The principal function of this algorithm is to use regular GPS state measurements to determine the controlled satellite's tracking error from a set of reference trajectories in the local-vertical/local-horizontal reference frame. A linear state-feedback control law---designed using a linear quadratic regulator method---calculates the optimal thrusts necessary to correct this error and communicates the thrust directions to the attitude control system and the thrust durations to the propulsion system. The control system is developed to minimize the conflicting metrics of tracking error and DeltaV requirements. To reconfigure the formation, an optimization algorithm is designed using the analytical solution to the state-space equation and the Hill-Clohessy-Wiltshire state transition matrix to solve for dual-thrust reconfiguration maneuvers. The resulting trajectories require low DeltaV, use finite-time thrusts and are accurate in a fully nonlinear orbital environment. This algorithm will be used to control the CanX-4&5 formation flying demonstration mission. In addition, an iterative method which numerically generates quasi periodic trajectories for a satellite formation is presented. This novel technique utilizes a shooting approach to the Newton method to close the relative deputy trajectory over a specific number of orbits, then fits the actual perturbed motion of the deputy with a Fourier series to enforce periodicity. This process is applied to two well-known satellite formations: a projected circular orbit and a J2-invariant formation. Compared to conventional formations, these resulting quasi-periodic trajectories require a dramatically lower control effort to maintain and could therefore be used to extend DeltaV-limited formation flying missions. Finally, an analytical study of the stability of the formation flying algorithm is conducted. To facilitate

  15. A real-time guidance algorithm for aerospace plane optimal ascent to low earth orbit (United States)

    Calise, A. J.; Flandro, G. A.; Corban, J. E.


    Problems of onboard trajectory optimization and synthesis of suitable guidance laws for ascent to low Earth orbit of an air-breathing, single-stage-to-orbit vehicle are addressed. A multimode propulsion system is assumed which incorporates turbojet, ramjet, Scramjet, and rocket engines. An algorithm for generating fuel-optimal climb profiles is presented. This algorithm results from the application of the minimum principle to a low-order dynamic model that includes angle-of-attack effects and the normal component of thrust. Maximum dynamic pressure and maximum aerodynamic heating rate constraints are considered. Switching conditions are derived which, under appropriate assumptions, govern optimal transition from one propulsion mode to another. A nonlinear transformation technique is employed to derived a feedback controller for tracking the computed trajectory. Numerical results illustrate the nature of the resulting fuel-optimal climb paths.

  16. Confirming the transit of the Earth-mass planet orbiting Alpha Centauri B (United States)

    Demory, Brice-Olivier


    One of the most fascinating exoplanet findings of the past years is undoubtedly the discovery of an Earth-mass exoplanet orbiting Alpha Centauri B. Alpha Cen Bb orbits one component of the closest stellar system to the Earth and has the potential to become a true Rosetta stone in exoplanet science, if its transiting nature were revealed. In 2013, we observed Alpha Centauri B during 16 orbits with HST/STIS to search for the transit of Alpha Cen Bb. We recently carried out in-depth photometric analyses of this dataset that resulted in the clear detection of a transit-shaped pattern. Several factors, however, prevent us from securing the planetary nature of the signal found in the STIS time-series. Now that we know where and when to look for, we propose to confirm the repeatability of this signal and to firmly establish Alpha Cen Bb's existence and tighten its physical and orbital properties. We base our observing strategy on the successful approach employed just one year ago with the same instrument. Until Aug 9th 2014, combination of HST available roll angles, Alpha Cen binary separation and position angle will match the nearly-ideal configuration we had in July 2013. It would even be possible to benefit from CVZ status from 24/7/2014 to 28/7/2014, in which one transit of Alpha Centauri Bb is expected. HST/STIS is the only facility able to confirm a transit from such a small planet at a high confidence level.

  17. Satellite formation design in orbits of high eccentricity for missions with performance criteria specified over a region of interest (United States)

    Roscoe, Christopher William Thomas

    Several methods are presented for the design of satellite formations for science missions in high-eccentricity reference orbits with quantifiable performance criteria specified throughout only a portion the orbit, called the Region of Interest (RoI). A modified form of the traditional average along-track drift minimization condition is introduced to account for the fact that performance criteria are only specified within the RoI, and a robust formation design algorithm (FDA) is defined to improve performance in the presence of formation initialization errors. Initial differential mean orbital elements are taken as the design variables and the Gim-Alfriend state transition matrix (G-A STM) is used for relative motion propagation. Using mean elements and the G-A STM allows for explicit inclusion of J2 perturbation effects in the design process. The methods are applied to the complete formation design problem of the NASA Magnetospheric Multiscale (MMS) mission and results are verified using the NASA General Mission Analysis Tool (GMAT). Since satellite formations in high-eccentricity orbits will spend long times at high altitude, third-body perturbations are an important design consideration as well. A detailed analytical analysis of third-body perturbation effects on satellite formations is also performed and averaged dynamics are derived for the particular case of the lunar perturbation. Numerical results of the lunar perturbation analysis are obtained for the example application of the MMS mission and verified in GMAT.

  18. AMS_02 Particle Physics Detector Technologies Orbiting the Earth (1/2)

    CERN Multimedia

    CERN. Geneva


    AMS-02 has taken the high performance technologies used in particle physics and implemented them for use in low Earth orbit. Safety aspects for the Space Shuttle flight, that carried AMS_02 to the International Space Station, Space environment and inaccessibility during the life of AMS_02 are some of the aspects which have driven the design of the experiment. The technical challenges to build such a detector have been surmounted through the close collaboration amongst the AMS scientists and industries around the world. Their efforts have resulted in the development of new technologies and higher standards of precision.

  19. AMS_02 Particle Physics Detector Technologies Orbiting the Earth (2/2)

    CERN Multimedia

    CERN. Geneva


    AMS-02 has taken the high performance technologies used in particle physics and implemented them for use in low Earth orbit. Safety aspects for the Space Shuttle flight, that carried AMS_02 to the International Space Station, Space environment and inaccessibility during the life of AMS_02 are some of the aspects which have driven the design of the experiment. The technical challenges to build such a detector have been surmounted through the close collaboration amongst the AMS scientists and industries around the world. Their efforts have resulted in the development of new technologies and higher standards of precision.

  20. An optimum organizational structure for a large earth-orbiting multidisciplinary Space Base (United States)

    Ragusa, J. M.


    The purpose of this exploratory study was to identify an optimum hypothetical organizational structure for a large earth-orbiting multidisciplinary research and applications (R&A) Space Base manned by a mixed crew of technologists. Since such a facility does not presently exist, in situ empirical testing was not possible. Study activity was, therefore, concerned with the identification of a desired organizational structural model rather than the empirical testing of it. The essential finding of this research was that a four-level project type 'total matrix' model will optimize the efficiency and effectiveness of Space Base technologists.

  1. Adaptive Terminal Sliding Mode Control of Electromagnetic Spacecraft Formation Flying in Near-Earth Orbits

    Directory of Open Access Journals (Sweden)

    Jingrui Zhang


    Full Text Available An adaptive terminal sliding mode control for six-degree-of-freedom electromagnetic spacecraft formation flying (EMFF in near-Earth orbits is presented. By using terminal sliding mode (TSM technique, the output tracking error can converge to zero in finite time, and strong robustness with respect to disturbance forces can be guaranteed. Based on a rotated frame Fr and the adaptive TSM controller, the special magnetic moment of the steerable magnetic dipole is computed. The angular momentum management strategy (AMM is implemented in a periodically switching fashion, by which the angular momentum buildup was limited. Illustrative simulations of EMFF are conducted to verify the effectiveness of the proposed controller.

  2. Lunar shadow eclipse prediction models for the Earth orbiting spacecraft: Comparison and application to LEO and GEO spacecrafts (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kulshrestha, Shivali; Srivastava, Ashutosh; Bhaskar, M. K.; Kushvah, Badam Singh; Shiggavi, Prakash; Vallado, David A.


    A solar eclipse occurs when the Sun, Moon and Earth are aligned in such a way that shadow of the Moon falls on the Earth. The Moon's shadow also falls on the Earth orbiting spacecraft. In this case, the alignment of the Sun, Moon, and spacecraft is similar to that of the Sun, Moon, and Earth but this phenomenon is often referred as a lunar eclipse falling on the spacecraft. Lunar eclipse is not as regular in terms of times of occurrence, duration, and depth as the Earth shadow eclipse and number of its occurrence per orbital location per year ranges from zero to four with an average of two per year; a spacecraft may experience two to three lunar eclipses within a twenty-four hour period [2]. These lunar eclipses can cause severe spacecraft operational problems. This paper describes two lunar shadow eclipse prediction models using a projection map approach and a line of intersection method by extending the Earth shadow eclipse models described by Srivastava et al. [10,11] for the Earth orbiting spacecraft. The attractive feature of both models is that they are much easier to implement. Both mathematical models have been simulated for two Indian low Earth orbiting spacecrafts: Oceansat-2, Saral-1, and two geostationary spacecrafts: GSAT-10, INSAT-4CR. Results obtained by the models compare well with lunar shadow model given by Escobal and Robertson [12], and high fidelity commercial software package, Systems Tool Kit (STK) of AGI.

  3. Theory and design methods of special space orbits

    CERN Document Server

    Zhang, Yasheng; Zhou, Haijun


    This book focuses on the theory and design of special space orbits. Offering a systematic and detailed introduction to the hovering orbit, spiral cruising orbit, multi-target rendezvous orbit, initiative approaching orbit, responsive orbit and earth pole-sitter orbit, it also discusses the concept, theory, design methods and application of special space orbits, particularly the design and control method based on kinematics and astrodynamics. In addition the book presents the latest research and its application in space missions. It is intended for researchers, engineers and postgraduates, especially those working in the fields of orbit design and control, as well as space-mission planning and research.

  4. An analysis of propulsion options for transport of lunar materials to earth orbit (United States)

    Frisbee, R. H.; Jones, R. M.


    This paper describes the results of analyses of space-based transportation systems for the transport of extraterrestrial materials from their point of origin on the lunar surface to final delivery point in earth orbit and transport of equipment and supplies for extraterrestrial processing to the operational site. The emphasis has been on the use of near-term (pre-year 2000) propulsion systems, such as advanced chemical (H2, O2) and nuclear-electric systems. More exotic systems (mass drivers, nuclear-thermal rockets, etc.) were also considered to evaluate the potential to be gained by use of post-year 2000 technologies. Finally, the effects of using extraterrestrial propellants (e.g., H2 from lunar polar water-ice for chemical systems) were compared to those of propulsion systems deriving all or part of their propellants from the earth.

  5. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D., E-mail: [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)


    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  6. The Mission Accessible Near-Earth Objects Survey (MANOS): photometric results (United States)

    Thirouin, Audrey; Moskovitz, Nicholas; Binzel, Richard; Christensen, Eric J.; DeMeo, Francesca; Person, Michael J.; Polishook, David; Thomas, Cristina; Trilling, David E.; Willman, Mark; Hinkle, Mary L.; Burt, Brian; Avner, Dan


    The Mission Accessible Near-Earth Object Survey (MANOS) is a physical characterization survey of Near-Earth Objects (NEOs) to provide physical data for several hundred mission accessible NEOs across visible and near-infrared wavelengths. Using a variety of 1-m to 8-m class telescopes, we observe 5 to 10 newly discovered sub-km NEOs per month in order to derive their rotational properties and taxonomic class.Rotational data can provide useful information about physical properties, like shape, surface heterogeneity/homogeneity, density, internal structure, and internal cohesion. Here, we present results of the MANOS photometric survey for more than 200 NEOs. We report lightcurves from our first three years of observing and show objects with rotational periods from a couple of hours down to a few seconds. MANOS found the three fastest rotators known to date with rotational periods below 20s. A physical interpretation of these ultra-rapid rotators is that they are bound through a combination of cohesive and/or tensile strength rather than gravity. Therefore, these objects are important to understand the internal structure of NEOs. Rotational properties are used for statistical study to constrain overall properties of the NEO population. We also study rotational properties according to size, and dynamical class. Finally, we report a sample of NEOs that are fully characterized (lightcurve and visible spectra) as the most suitable candidates for a future robotic or human mission. Viable mission targets are objects with a rotational period >1h, and a delta-v lower than 12 km/s. Assuming the MANOS rate of object characterization, and the current NEO population estimates by Tricarico (2016), and by Harris and D'Abramo (2015), 10,000 to 1,000,000 NEOs with diameters between 10m and 1km are expected to be mission accessible. We acknowledge funding support from NASA NEOO grant number NNX14AN82G, and NOAO survey program.

  7. Trajectory design for a rendezvous mission to Earth's Trojan asteroid 2010 TK7 (United States)

    Lei, Hanlun; Xu, Bo; Zhang, Lei


    In this paper a rendezvous mission to the Earth's Trojan asteroid 2010 TK7 is proposed, and preliminary transfer trajectories are designed. Due to the high inclination (∼ 20.9°) of the target asteroid relative to the ecliptic plane, direct transfers usually require large amounts of fuel consumption, which is beyond the capacity of current technology. As gravity assist technique could effectively change the inclination of spacecraft's trajectory, it is adopted to reduce the launch energy and rendezvous velocity maneuver. In practical computation, impulsive and low-thrust, gravity-assisted trajectories are considered. Among all the trajectories computed, the low-thrust gravity-assisted trajectory with Venus-Earth-Venus (V-E-V) swingby sequence performs the best in terms of propellant mass. For a spacecraft with initial mass of 800 kg , propellant mass of the best trajectory is 36.74 kg . Numerical results indicate that both the impulsive and low-thrust, gravity-assisted trajectories corresponding to V-E-V sequence could satisfy mission constraints, and can be applied to practical rendezvous mission.

  8. Multi-Mission Earth Vehicle Subsonic Dynamic Stability Testing and Analyses (United States)

    Glaab, Louis J.; Fremaux, C. Michael


    Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes, retro-rockets, and reaction control systems and rely on the natural aerodynamic stability of the vehicle throughout the Entry, Descent, and Landing (EDL) phase of flight. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs for an array of missions and develop and visualize the trade space. Testing in NASA Langley?s Vertical Spin Tunnel (VST) was conducted to significantly improve M-SAPE?s subsonic aerodynamic models. Vehicle size and shape can be driven by entry flight path angle and speed, thermal protection system performance, terminal velocity limitations, payload mass and density, among other design parameters. The objectives of the VST testing were to define usable subsonic center of gravity limits, and aerodynamic parameters for 6-degree-of-freedom (6-DOF) simulations, for a range of MMEEV designs. The range of MMEEVs tested was from 1.8m down to 1.2m diameter. A backshell extender provided the ability to test a design with a much larger payload for the 1.2m MMEEV.

  9. Ocean Surface Topography Mission (OSTM) /Jason-3: Orbital Information, 2015- (NODC Accession 0122598) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Jason-3 is the fourth mission in U.S.-European series of satellite missions that measure the height of the ocean surface. Scheduled to launch in 2015, the mission...

  10. Impacts of Earth rotation parameters on GNSS ultra-rapid orbit prediction: Derivation and real-time correction (United States)

    Wang, Qianxin; Hu, Chao; Xu, Tianhe; Chang, Guobin; Hernández Moraleda, Alberto


    Analysis centers (ACs) for global navigation satellite systems (GNSSs) cannot accurately obtain real-time Earth rotation parameters (ERPs). Thus, the prediction of ultra-rapid orbits in the international terrestrial reference system (ITRS) has to utilize the predicted ERPs issued by the International Earth Rotation and Reference Systems Service (IERS) or the International GNSS Service (IGS). In this study, the accuracy of ERPs predicted by IERS and IGS is analyzed. The error of the ERPs predicted for one day can reach 0.15 mas and 0.053 ms in polar motion and UT1-UTC direction, respectively. Then, the impact of ERP errors on ultra-rapid orbit prediction by GNSS is studied. The methods for orbit integration and frame transformation in orbit prediction with introduced ERP errors dominate the accuracy of the predicted orbit. Experimental results show that the transformation from the geocentric celestial references system (GCRS) to ITRS exerts the strongest effect on the accuracy of the predicted ultra-rapid orbit. To obtain the most accurate predicted ultra-rapid orbit, a corresponding real-time orbit correction method is developed. First, orbits without ERP-related errors are predicted on the basis of ITRS observed part of ultra-rapid orbit for use as reference. Then, the corresponding predicted orbit is transformed from GCRS to ITRS to adjust for the predicted ERPs. Finally, the corrected ERPs with error slopes are re-introduced to correct the predicted orbit in ITRS. To validate the proposed method, three experimental schemes are designed: function extrapolation, simulation experiments, and experiments with predicted ultra-rapid orbits and international GNSS Monitoring and Assessment System (iGMAS) products. Experimental results show that using the proposed correction method with IERS products considerably improved the accuracy of ultra-rapid orbit prediction (except the geosynchronous BeiDou orbits). The accuracy of orbit prediction is enhanced by at least 50

  11. Design and Applications of Solar Sail Periodic Orbits in the Non-Autonomous Earth-Moon System

    NARCIS (Netherlands)

    Heiligers, M.J.; Macdonald, Malcolm; Parker, Jeffrey S.; Turner, J.D.; Wawrzyniak, G.G.; Cerven, W.T.; Majji, M.


    Solar sailing has great potential for a range of high-energy and long duration mis-sions in the Sun-Earth system. This paper extends this potential to the non-autonomous Earth-Moon system through the use of a differential correction scheme, and by selecting suitable in-plane and out-of-plane sail

  12. Near Earth Asteroid Rendezvous (NEAR) Revised Eros Orbit Phase Trajectory Design (United States)

    Helfrich, J; Miller, J. K.; Antreasian, P. G.; Carranza, E.; Williams, B. G.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.


    Trajectory design of the orbit phase of the NEAR mission involves a new process that departs significantly from those procedures used in previous missions. In most cases, a precise spacecraft ephemeris is designed well in advance of arrival at the target body. For NEAR, the uncertainty in the dynamic environment around Eros does not allow the luxury of a precise spacecraft trajectory to be defined in advance. The principal cause of this uncertainty is the limited knowledge oi' the gravity field a,-id rotational state of Eros. As a result, the concept for the NEAR trajectory design is to define a number of rules for satisfying spacecraft, mission, and science constraints, and then apply these rules to various assumptions for the model of Eros. Nominal, high, and low Eros mass models are used for testing the trajectory design strategy and to bracket the ranges of parameter variations that are expected upon arrival at the asteroid. The final design is completed after arrival at Eros and determination of the actual gravity field and rotational state. As a result of the unplanned termination of the deep space rendezvous maneuver on December 20, 1998, the NEAR spacecraft passed within 3830 km of Eros on December 23, 1998. This flyby provided a brief glimpse of Eros, and allowed for a more accurate model of the rotational parameters and gravity field uncertainty. Furthermore, after the termination of the deep space rendezvous burn, contact with the spacecraft was lost and the NEAR spacecraft lost attitude control. During the subsequent gyrations of the spacecraft, hydrazine thruster firings were used to regain attitude control. This unplanned thruster activity used Much of the fuel margin allocated for the orbit phase. Consequently, minimizing fuel consumption is now even more important.

  13. The ESA earth observation polar platform programme (United States)

    Rast, M.; Readings, C. J.


    The overall scenario of ESA earth observation polar platform program is reviewed with particular attention given to instruments currently being considered for flight on the first European polar platforms. The major objectives of the mission include monitoring the earth's environment on various scales; management and monitoring of the earth's resources; improvement of the service provided to the worldwide operational meteorological community, investigation of the structure and dynamics of the earth's crust and interior. The program encompasses four main elements: an ERS-1 follow-on mission (ERS-2), a solid earth gravity mission (Aristoteles), a Meteosat Second Generation, and a series of polar orbit earth observation missions.

  14. Evolutionary algorithms to optimize low-thrust trajectory design in spacecraft orbital precession mission


    Shirazi A.; Ceberio J.; Lozano J.A.


    In space environment, perturbations make the spacecraft lose its predefined orbit in space. One of these undesirable changes is the in-plane rotation of space orbit, denominated as orbital precession. To overcome this problem, one option is to correct the orbit direction by employing low-thrust trajectories. However, in addition to the orbital perturbation acting on the spacecraft, a number of parameters related to the spacecraft and its propulsion system must be optimized. This article lays ...

  15. OSIRIS-REx A NASA Mission to a Near Earth Asteroid!...and Other Recent Happenings in the Solar System (United States)

    Moreau, Michael C.


    The OSIRIS-REx Mission launches in 2016 Arrives at Asteroid Bennu-2018 Returns a sample to Earth -2023 The mission, OSIRIS-REx, will visit an asteroid and return a sample from the early Solar System to help us understand how our Solar System formed.

  16. A super-Earth orbiting the nearby M dwarf GJ 536 (United States)

    Suárez Mascareño, A.; González Hernández, J. I.; Rebolo, R.; Astudillo-Defru, N.; Bonfils, X.; Bouchy, F.; Delfosse, X.; Forveille, T.; Lovis, C.; Mayor, M.; Murgas, F.; Pepe, F.; Santos, N. C.; Udry, S.; Wünsche, A.; Velasco, S.


    We report the discovery of a super-Earth orbiting the star GJ 536 based on the analysis of the radial-velocity time series from the HARPS and HARPS-N spectrographs. GJ 536 b is a planet with a minimum mass Msini of 5.36 ± 0.69 M⊕; it has an orbital period of 8.7076 ± 0.0025 d at a distance of 0.066610(13) AU, and an orbit that is consistent with circular. The host star is the moderately quiet M1 V star GJ 536, located at 10 pc from the Sun. We find the presence of a second signal at 43 d that we relate to stellar rotation after analysing the time series of Ca II H&K and Hα spectroscopic indicators and photometric data from the ASAS archive. We find no evidence linking the short period signal to any activity proxy. We also tentatively derived a stellar magnetic cycle of less than 3 yr. The data used in this paper (Table A.1) are only available at the CDS via anonymous ftp to ( or via

  17. ARMA Prediction of SBAS Ephemeris and Clock Corrections for Low Earth Orbiting Satellites

    Directory of Open Access Journals (Sweden)

    Jeongrae Kim


    Full Text Available For low earth orbit (LEO satellite GPS receivers, space-based augmentation system (SBAS ephemeris/clock corrections can be applied to improve positioning accuracy in real time. The SBAS correction is only available within its service area, and the prediction of the SBAS corrections during the outage period can extend the coverage area. Two time series forecasting models, autoregressive moving average (ARMA and autoregressive (AR, are proposed to predict the corrections outside the service area. A simulated GPS satellite visibility condition is applied to the WAAS correction data, and the prediction accuracy degradation, along with the time, is investigated. Prediction results using the SBAS rate of change information are compared, and the ARMA method yields a better accuracy than the rate method. The error reductions of the ephemeris and clock by the ARMA method over the rate method are 37.8% and 38.5%, respectively. The AR method shows a slightly better orbit accuracy than the rate method, but its clock accuracy is even worse than the rate method. If the SBAS correction is sufficiently accurate comparing with the required ephemeris accuracy of a real-time navigation filter, then the predicted SBAS correction may improve orbit determination accuracy.

  18. Coupled thermo-orbital evolution of tidally-evolved Earth-like planets (United States)

    Behounkova, Marie; Walterova, Michaela; Cadek, Ondrej; Tobie, Gabriel; Choblet, Gael


    Progress in detection techniques of exoplanets inspired increasing number of studies focused on their internal dynamics and evolution. The detection methods tend to favor the discovery of short-period exoplanets, that are predicted to get rapidly tidally locked. During the locking process planets despin and a significant amount of tidal heating may contribute to the thermal budget of the planet. Moreover, tidally locked exoplanets exhibit large surface temperature contrasts between sub-stellar and anti-stellar sides due to uneven insolation which influence the convection pattern and cooling of the planet. Here, we will present the evolution of tidally locked Earth-like exoplanets using numerical tool Antigone (Behounkova et al., 2010, 2011) coupling long-term internal evolution, tidal dissipation (taking into account Maxwell or Andrade rheology) and uneven insolation pattern. For constant orbital parameters, we will focus on numerical simulation of the heat transfer in exoEarths for various rheological properties of planet and various values of spin-orbit resonance, semi-major axis, eccentricity and luminosity of star. In the case of effective heat transfer, our results suggest that the melting is mainly observed within the upper part of the mantle for tidal heating lower than 100TW . For tidal heating higher than 100TW, the melt is produced also within the deep part of the mantle and degree-2 convection is enhanced due to tidal heating pattern. For large tidal heating (larger than 1000TW), global melting is observed and temperature field is homogenized due to global melting, the heat transfer is mainly due to melt extraction and advection is suppressed. We will further present first results of coupled orbital-internal evolution of planets without companion using numerical model of orbital evolution with realistic (Maxwell or Andrade) rheology (Walterova et al., in prep). We will concentrate on the capture into the spin-orbit resonance. Special attention will be

  19. Design and "As Flown" Radiation Environments for Materials in Low Earth Orbit (United States)

    Minow, Joseph; McWilliams, Brett; Altstatt, Richard; Koontz, Steven


    A conservative design approach was adopted by the International Space Station Program for specifying total ionizing radiation dose requirements for use in selecting and qualifying materials for construction of the International Space Station. The total ionizing dose design environment included in SSP 30512 Space Station Ionizing Radiation Design Environment is based on trapped proton and electron fluence derived from the solar maximum versions of the AE-8 and AP-8 models, respectively, specified for a circular orbit at 500 km altitude and 51.7 degree inclination. Since launch, the range of altitudes utilized for Space Station operations vary from a minimum of approximately 330 km to a maximum of approximately 405 km with a mean operational altitude less than 400 km. The design environment, therefore, overestimates the radiation environment because the particle flux in the South Atlantic Anomaly is the primary contributor to radiation dose in low Earth orbit and flux within the Anomaly is altitude dependent. In addition, a 2X multiplier is often applied to the design environment to cover effects from the contributions of galactic cosmic rays, solar energetic particle events, geomagnetic storms, and uncertainties in the trapped radiation models which are not explicitly included in the design environment. Application of this environment may give radiation dose overestimates on the order of 1OX to 30X for materials exposed to the space environment, suggesting that materials originally qualified for ten year exposures on orbit may be used for longer periods without replacement. In this paper we evaluate the "as flown" radiation environments derived from historical records of the ISS flight trajectory since launch and compare the results with the SSP 30512 design environment to document the magnitude of the radiation dose overestimate provided by the design environment. "As flown" environments are obtained from application of the AE-8/AP-8 trapped particle models along

  20. Orbits

    CERN Document Server

    Xu, Guochang


    This is the first book of the satellite era which describes orbit theory with analytical solutions of the second order with respect to all possible disturbances. Based on such theory, the algorithms of orbits determination are completely revolutionized.

  1. What next in mission? From the end of the earth to Jerusalem

    Directory of Open Access Journals (Sweden)

    M Masango


    Full Text Available This article sketches the impact of technology and globalisation on culture, and the results appear to be devastating. An appeal is made to churches to encourage missionary endeavours that reach out to the world. The challenge that African Churches face is, how they will take mission work, from the ends of the earth back to Jerusalem (Missionary Churches. A plea is made to pay respect to the creation of God, and to restore broken relationships. �Let thy Kingdom come�, is the final prayer.

  2. Human factors analysis of workstation design: Earth Radiation Budget Satellite Mission Operations Room (United States)

    Stewart, L. J.; Murphy, E. D.; Mitchell, C. M.


    A human factors analysis addressed three related yet distinct issues within the area of workstation design for the Earth Radiation Budget Satellite (ERBS) mission operation room (MOR). The first issue, physical layout of the MOR, received the most intensive effort. It involved the positioning of clusters of equipment within the physical dimensions of the ERBS MOR. The second issue for analysis was comprised of several environmental concerns, such as lighting, furniture, and heating and ventilation systems. The third issue was component arrangement, involving the physical arrangement of individual components within clusters of consoles, e.g., a communications panel.

  3. Multi-Mission Earth Entry Vehicle: Aerodynamic and Aerothermal Analysis of Trajectory Environments (United States)

    Trumble, Kerry; Dyakonov, Artem; Fuller, John


    Multi-mission Earth Entry Vehicle (MMEEV) is designed to deliver small payloads from space to Earth's surface by flying an uncontrolled ballistic entry, which ends with ground impact. The included range of entry velocities is from 10 to 16 km/s. The range of ballistic coefficients is from 41.94 to 128.74 kg/m2, which insures a low subsonic terminal velocity on the order of 50 m/sec. The range of entry flight path angles, considered in this analysis is from -5 to -25 degrees. The assessment and parametric characterization of aeroheating and aerodynamic performance of the capsule during entry is the subject of this paper.

  4. Development status of the EarthCARE Mission and its atmospheric Lidar (United States)

    Hélière, A.; Wallace, K.; Pereira Do Carmo, J.; Lefebvre, A.; Eisinger, M.; Wehr, T.


    The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop as part of ESA's Living Planet Programme, the third Earth Explorer Core Mission, EarthCARE, with the fundamental objective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earth's atmosphere. EarthCARE payload consists of two active and two passive instruments: an ATmospheric LIDar (ATLID), a Cloud Profiling Radar (CPR), a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer (BBR). The four instruments data are processed individually and in a synergetic manner to produce a large range of products, which include vertical profiles of aerosols, liquid water and ice, observations of cloud distribution and vertical motion within clouds, and will allow the retrieval of profiles of atmospheric radiative heating and cooling. Operating in the UV range at 355 nm, ATLID provides atmospheric echoes with a vertical resolution up to 100 m from ground to an altitude of 40 km. Thanks to a high spectral resolution filtering, the lidar is able to separate the relative contribution of aerosol (Mie) and molecular (Rayleigh) scattering, which gives access to aerosol optical depth. Co-polarised and cross-polarised components of the Mie scattering contribution are also separated and measured on dedicated channels. This paper gives an overview of the mission science objective, the satellite configuration with its four instruments and details more specifically the implementation and development status of the Atmospheric Lidar. Manufacturing status and first equipment qualification test results, in particular for what concerns the laser transmitter development are presented.

  5. Near Earth Asteroid Scout: NASA's Solar Sail Mission to a NEA (United States)

    Johnson, Les; Castillo-Rogez, Julie; Dervan, Jared


    NASA is developing a solar sail propulsion system for use on the Near Earth Asteroid (NEA) Scout reconnaissance mission and laying the groundwork for their use in future deep space science and exploration missions. Solar sails use sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like sail made of a lightweight, highly reflective material. This continuous photon pressure provides propellant-less thrust, allowing for very high delta V maneuvers on long-duration, deep space exploration. Since reflected light produces thrust, solar sails require no onboard propellant. The Near Earth Asteroid (NEA) Scout mission, funded by NASA’s Advanced Exploration Systems Program and managed by NASA MSFC, will use the sail as primary propulsion allowing it to survey and image Asteroid 1991VG and, potentially, other NEA’s of interest for possible future human exploration. The NEA Scout spacecraft is housed in a 6U CubeSat-form factor and utilizes an 86 square meter solar sail for a total mass less than 14 kilograms. The mission is in partnership with the Jet Propulsion Laboratory with support from Langley Research Center and science participants from various institutions. NEA Scout will be launched on the maiden flight of the Space Launch System in 2019. The solar sail for NEA Scout will be based on the technology developed and flown by the NASA NanoSail-D and flown on The Planetary Society’s Lightsail-A. Four approximately-7-meter stainless steel booms wrapped on two spools (two overlapping booms per spool) will be motor driven and pull the sail from its stowed volume. The sail material is an aluminized polyimide approximately 2.5 microns thick. As the technology matures, solar sails will increasingly be used to enable science and exploration missions that are currently impossible or prohibitively expensive using traditional chemical and electric propulsion systems. This paper will summarize the status of the NEA Scout mission and solar

  6. Electro-Optical Payloads and CubeSat Missions for Earth and Space Science (United States)

    Swenson, C.; Marchant, A.


    Small, low-power electro-optical scientific payloads are required if small satellites and CubeSats are to become significant enablers of new science. Although these are just one class of scientific instrumentation they have often played a key role in many scientific discoveries. The most significant advances in Earth and space science, over the next decade are most likely to derive from new observational techniques. The connection between advances in scientific understanding and technology has historically been demonstrated across many disciplines and time. In this paper we present a review of three such sensors and the associated CubeSat missions and scientific investigation enabled. Each mission involves a relatively recently developed small electro-optical sensor which is tightly integrated with the small satellite bus in to a "Science Craft". The first is the NSF funded OPAL mission which makes use of a high-sensitivity, hyper-spectral limb imager to observe the daytime O2 A-band (near 762nm) emission. These observations allow the temperature of the lower thermosphere to be determined and address questions on the energy budget and response of the thermosphere to geomagnetic storms. The second is the MeNISCuS mission Methane Nadir Imaging Spatial-heterodyne CubeSat Spectrometer which is a demonstration of the volume holographic grating (VHG) spatial heterodyne spectrometer developed under a NASA-sponsored STTR contract. Methane (CH4) is the second most important greenhouse gas and although burning methane produces less CO2 than oil or coal, methane's global warming potential is about ~30 times higher. As a result, if methane leak rates are greater than 3-5%, the warming potential will outweigh the benefit of reduced CO2. The sources of such leaks can be discovered using missions like MeNISCuS. The third instrument and mission is SEDI a CubeSat scaled Fabry-Perot spectrometer focused on a narrow band around the OI(630) red line for observing winds in the

  7. Evolution of Satellite Imagers and Sounders for Low Earth Orbit and Technology Directions at NASA (United States)

    Pagano, Thomas S.; McClain, Charles R.


    Imagers and Sounders for Low Earth Orbit (LEO) provide fundamental global daily observations of the Earth System for scientists, researchers, and operational weather agencies. The imager provides the nominal 1-2 km spatial resolution images with global coverage in multiple spectral bands for a wide range of uses including ocean color, vegetation indices, aerosol, snow and cloud properties, and sea surface temperature. The sounder provides vertical profiles of atmospheric temperature, water vapor cloud properties, and trace gases including ozone, carbon monoxide, methane and carbon dioxide. Performance capabilities of these systems has evolved with the optical and sensing technologies of the decade. Individual detectors were incorporated on some of the first imagers and sounders that evolved to linear array technology in the '80's. Signal-to-noise constraints limited these systems to either broad spectral resolution as in the case of the imager, or low spatial resolution as in the case of the sounder. Today's area 2-dimensional large format array technology enables high spatial and high spectral resolution to be incorporated into a single instrument. This places new constraints on the design of these systems and enables new capabilities for scientists to examine the complex processes governing the Earth System.

  8. NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids (United States)

    Nuth, Joseph A.


    Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the

  9. Analytic model for the long-term evolution of circular Earth satellite orbits including lunar node regression (United States)

    Zhu, Ting-Lei; Zhao, Chang-Yin; Zhang, Ming-Jiang


    This paper aims to obtain an analytic approximation to the evolution of circular orbits governed by the Earth's J2 and the luni-solar gravitational perturbations. Assuming that the lunar orbital plane coincides with the ecliptic plane, Allan and Cook (Proc. R. Soc. A, Math. Phys. Eng. Sci. 280(1380):97, 1964) derived an analytic solution to the orbital plane evolution of circular orbits. Using their result as an intermediate solution, we establish an approximate analytic model with lunar orbital inclination and its node regression be taken into account. Finally, an approximate analytic expression is derived, which is accurate compared to the numerical results except for the resonant cases when the period of the reference orbit approximately equals the integer multiples (especially 1 or 2 times) of lunar node regression period.

  10. Preliminary error budget analysis of the coronagraphic instrument metis for the solar orbiter ESA mission (United States)

    Da Deppo, Vania; Poletto, Luca; Crescenzio, Giuseppe; Fineschi, Silvano; Antonucci, Ester; Naletto, Giampiero


    METIS, the Multi Element Telescope for Imaging and Spectroscopy, is the solar coronagraph foreseen for the ESA Solar Orbiter mission. METIS is conceived to image the solar corona from a near-Sun orbit in three different spectral bands: in the HeII EUV narrow band at 30.4 nm, in the HI UV narrow band at 121.6 nm, and in the polarized visible light band (590 - 650 nm). It also incorporates the capability of multi-slit spectroscopy of the corona in the UV/EUV range at different heliocentric heights. METIS is an externally occulted coronagraph which adopts an "inverted occulted" configuration. The Inverted external occulter (IEO) is a small circular aperture at the METIS entrance; the Sun-disk light is rejected by a spherical mirror M0 through the same aperture, while the coronal light is collected by two annular mirrors M1-M2 realizing a Gregorian telescope. To allocate the spectroscopic part, one portion of the M2 is covered by a grating (i.e. approximately 1/8 of the solar corona will not be imaged). This paper presents the error budget analysis for this new concept coronagraph configuration, which incorporates 3 different sub-channels: UV and EUV imaging sub-channel, in which the UV and EUV light paths have in common the detector and all of the optical elements but a filter, the polarimetric visible light sub-channel which, after the telescope optics, has a dedicated relay optics and a polarizing unit, and the spectroscopic sub-channel, which shares the filters and the detector with the UV-EUV imaging one, but includes a grating instead of the secondary mirror. The tolerance analysis of such an instrument is quite complex: in fact not only the optical performance for the 3 sub-channels has to be maintained simultaneously, but also the positions of M0 and of the occulters (IEO, internal occulter and Lyot stop), which guarantee the optimal disk light suppression, have to be taken into account as tolerancing parameters. In the aim of assuring the scientific

  11. Orbiter/carrier separation for the ALT free flight no. 1 reference trajectories. Mission planning, mission analysis and software formulation (United States)

    Glenn, G. M.


    Details of the generation of the separation trajectories are discussed. The analysis culminated in definition of separation trajectories between physical separation and orbiter/carrier vortex clearance. Specifications, assumptions and analytical approach used to generate the separation trajectories are presented. Results of the analytical approach are evaluated. Conclusions and recommendations are summarized. Supporting references are listed.

  12. Reducing the Risk and Improving Mission Success for NASA's Human Mission to a Near-Earth Asteroid: How Many Robotic Surveyors? (United States)

    Smith, Jeffrey H.; Lincoln, William P.; Weisbin, Charles R.


    NASA's recent attention and interest in sending a human mission to land on a Near-Earth asteroid raises the question of need for a robotic surveyor. This paper describes a Bayesian approach for comparing the productivity and cost-risk tradeoffs of sending (versus not sending) one or more robotic surveyor missions prior to a human mission to land on an asteroid. The probability of finding an asteroid suitable for landing was derived from an analysis of more than 1200 asteroids in order to define a quantitative estimate of suitability. The low cost of the surveyors relative to the human mission underlined the multi-surveyor strategy as relatively inexpensive insurance against the risks of encountering an unsuitable asteroid for landing on arrival by a human mission.

  13. Impact Foam Testing for Multi-Mission Earth Entry Vehicle Applications (United States)

    Glaab, Louis J.; Agrawal, Paul; Hawbaker, James


    Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes and retro-rockets, instead using built-in impact attenuators to absorb energy remaining at impact to meet landing loads requirements. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs and develop the trade space. Testing was conducted to characterize the material properties of several candidate impact foam attenuators to enhance M-SAPE analysis. In the current effort, two different Rohacell foams were tested to determine their thermal conductivity in support of MMEEV design applications. These applications include thermal insulation during atmospheric entry, impact attenuation, and post-impact thermal insulation in support of thermal soak analysis. Results indicate that for these closed-cell foams, the effect of impact is limited on thermal conductivity due to the venting of the virgin material gas and subsequent ambient air replacement. Results also indicate that the effect of foam temperature is significant compared to data suggested by manufacturer's specifications.

  14. Uniform Foam Crush Testing for Multi-Mission Earth Entry Vehicle Impact Attenuation (United States)

    Patterson, Byron W.; Glaab, Louis J.


    Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes and retro-rockets, instead using built-in impact attenuators to absorb energy remaining at impact to meet landing loads requirements. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs and develop the trade space. Testing was conducted to characterize the material properties of several candidate impact foam attenuators to enhance M-SAPE analysis. In the current effort, four different Rohacell foams are tested at three different, uniform, strain rates (approximately 0.17, approximately 100, approximately 13,600%/s). The primary data analysis method uses a global data smoothing technique in the frequency domain to remove noise and system natural frequencies. The results from the data indicate that the filter and smoothing technique are successful in identifying the foam crush event and removing aberrations. The effect of strain rate increases with increasing foam density. The 71-WF-HT foam may support Mars Sample Return requirements. Several recommendations to improve the drop tower test technique are identified.

  15. Stellar orbits in the Galaxy and mass extinctions on the Earth: a connection? (United States)

    Porto de Mello, G. F.; Dias, W. S.; Lepine, J.; Lorenzo-Oliveira, D.; Kazu, R. S.


    The orbits of the stars in the disk of the Galaxy, and their passages through the Galactic spiral arms, are a rarely mentioned factor of biosphere stability which might be important for long-term planetary climate evolution, with a possible bearing on mass extinctions. The Sun lies very near the co-rotation radius, where stars revolve around the Galaxy in the same period as the density wave perturbations of the spiral arms (Dias & Lepine 2005). Conventional wisdom generally considers that this status makes for few passages through the spiral arms. Controversy still surrounds whether time spent inside or around spiral arms is dangerous to biospheres and conducive to mass extinctions (Bailer-Jones 2009). Possible threats include giant molecular clouds disturbing the Oort comet cloud and provoking heavy bombardment (Clube & Napier 1982); a higher exposure to cosmic rays near star forming regions triggering increased cloudiness in Earth's atmosphere and ice ages (Gies & Helsel 2005); and the destruction of Earth's ozone layer posed by supernova explosions (Gehrels et al 2003). We present detailed calculations of the history of spiral arm passages for all 212 solartype stars nearer than 20 parsecs, including the total time spent inside the spiral arms in the last 500 million years, when the spiral arm position can be traced with good accuracy. There is a very large diversity of stellar orbits amongst solar neighborhood solar-type stars, and the time fraction spent inside spiral arms can vary from a few percent to nearly half the time. The Sun, despite its proximity to the galactic co-rotation radius, has exceptionally low eccentricity and a low vertical velocity component, and therefore spends 40% of its lifetime crossing the spiral arms, more than nearly all nearby stars. We discuss the possible implications of this fact to the long-term habitability of the Earth, and possible correlations of the Sun's passage through the spiral arms with the five great mass

  16. Contamination Examples and Lessons from Low Earth Orbit Experiments and Operational Hardware (United States)

    Pippin, Gary; Finckenor, Miria M.


    Flight experiments flown on the Space Shuttle, the International Space Station, Mir, Skylab, and free flyers such as the Long Duration Exposure Facility, the European Retrievable Carrier, and the EFFU, provide multiple opportunities for the investigation of molecular contamination effects. Retrieved hardware from the Solar Maximum Mission satellite, Mir, and the Hubble Space Telescope has also provided the means gaining insight into contamination processes. Images from the above mentioned hardware show contamination effects due to materials processing, hardware storage, pre-flight cleaning, as well as on-orbit events such as outgassing, mechanical failure of hardware in close proximity, impacts from man-made debris, and changes due to natural environment factors.. Contamination effects include significant changes to thermal and electrical properties of thermal control surfaces, optics, and power systems. Data from several flights has been used to develop a rudimentary estimate of asymptotic values for absorptance changes due to long-term solar exposure (4000-6000 Equivalent Sun Hours) of silicone-based molecular contamination deposits of varying thickness. Recommendations and suggestions for processing changes and constraints based on the on-orbit observed results will be presented.

  17. Evaluation of thermal control coatings for use on solar dynamic radiators in low earth orbit (United States)

    Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.


    Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

  18. Sheath effects observed on a 10 meter high voltage panel in simulated low earth orbit plasma (United States)

    Mccox, J. E.; Konradi, A.


    A large (1m x 10m) flat surface of conductive material was biased to high voltage (+ or - 3000 V) to simulate the behavior of a large solar array in low earth orbit. The model array was operated in a plasma environment of 1,000 to 1,000,000/cu cm, with sufficient free space around it for the resulting plasma sheaths to develop unimpeded for 5-10 meters into the surrounding plasma. Measurements of the resulting sheath thickness were obtained. The observed thickness varied approximately as V to the 3/4 power and N to the 1/2 power. This effect appears to limit total current leakage from the test array until sheath dimensions exceed about 1 meter. Total leakage current was also measured with the array.

  19. Temporal Evolution of the Plasma Sheath Surrounding Solar Cells in Low Earth Orbit (United States)

    Willis, Emily M.; Pour, Maria Z. A.


    High voltage solar array interactions with the space environment can have a significant impact on array performance and spacecraft charging. Over the past 10 years, data from the International Space Station has allowed for detailed observations of these interactions over long periods of time. Some of the surprising observations have been floating potential transients, which were not expected and are not reproduced by existing models. In order to understand the underlying processes producing these transients, the temporal evolution of the plasma sheath surrounding the solar cells in low Earth orbit is being investigated. This study includes lumped element modeling and particle-in-cell simulation methods. This presentation will focus on recent results from the on-going investigations.

  20. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system (United States)

    Carter, P.; Beach, M. A.


    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  1. Orbital


    Yourshaw, Matthew Stephen


    Orbital is a virtual reality gaming experience designed to explore the use of traditional narrative structure to enhance immersion in virtual reality. The story structure of Orbital was developed based on the developmental steps of 'The Hero's Journey,' a narrative pattern identified by Joseph Campbell. Using this standard narrative pattern, Orbital is capable of immersing the player quickly and completely for the entirety of play time. MFA

  2. Viscoelastic characterization of thin-film polymers exposed to low Earth orbit (United States)

    Letton, Alan; Farrow, Allan; Strganac, Thomas


    The materials made available through the Long Duration Exposure Facility (LDEF) satellite provide a set of specimens that can be well characterized and have a known exposure history with reference to atomic oxygen and ultraviolet radiation exposure. Mechanical characteristics measured from control samples and exposed samples provide a data base for predicting the behavior of polymers in low earth orbit. Samples of 1.0 mil thick low density polyethylene were exposed to the low earth orbit environment for a period of six years. These materials were not directly exposed to ram atomic oxygen and offer a unique opportunity for measuring the effect of atomic oxygen and UV radiation on mechanical properties with little concern to the effect of erosion. The viscoelastic characteristics of these materials were measured and compared to the viscoelastic characteristics of control samples. To aid in differentiating the effects of changes in crystallinity resulting from thermal cycling, from the effects of changes in chemical structure resulting from atomic oxygen/UV attack to the polymer, a second set of control specimens, annealed to increase crystallinity, were measured as well. The resulting characterization of these materials will offer insight into the impact of atomic oxygen/UV on the mechanical properties of polymeric materials. The viscoelastic properties measured for the control, annealed, and exposed specimens were the storage and loss modulus as a function of frequency and temperature. From these datum is calculated the viscoelastic master curve derived using the principle of time/temperature superposition. Using the master curve, the relaxation modulus is calculated using the method of Ninomiya and Ferry. The viscoelastic master curve and the stress relaxation modulus provide a direct measure of the changes in the chemical or morphological structure. In addition, the effect of these changes on long-term and short-term mechanical properties is known directly. It

  3. ISA - An Accelerometer to Detect the Disturbing Accelerations Acting on the Mercury Planetary Orbiter of the BepiColombo ESA Cornerstone Mission to Mercury: on Ground Calibration (United States)

    Iafolla, V.; Lucchesi, D. M.; Nozzoli, S.; Santoli, F.; Fois, M.; Persichini, M.


    To reach the ambitious goals of the Radio Science Experiment of the BepiColombo space mission to Mercury, among which the planet structure and rotation and test Einstein's theory of General Relativity (GR) to an unprecedented accuracy, an accelerometer has been selected to fly on-board the MPO (Mercury Planetary Orbiter), the main spacecraft of the two to be placed around the innermost planet of our solar system around 2017. The key role of the on-board accelerometer is to remove from the list of unknowns the non-gravitational accelerations that disturbs the pure gravitational orbit of the MPO spacecraft in the strong radiation environment of Mercury. In this way the ``corrected'' orbit of the MPO may be regarded as a geodesic in the field of Mercury. Then, thanks to the very precise tracking from Earth, the possibility to study Mercury's center-of-mass around the Sun and estimate several parameters related to the planet structure and verify the theory of GR. The selected accelerometer named ISA (Italian Spring Accelerometer) is an high sensitive instrument with an intrinsic noise of 10-10 g⊕ / Hz (with g⊕ ≅ 9.8 m / s2) in the frequency band 3 . 10-5 -10-1 Hz. ISA is a three axis accelerometer with a characteristic configuration, in order to minimize the disturbing accelerations due to the gravity-gradients and the apparent forces on the Nadir pointing MPO spacecraft. Because of the complex and strong radiation environment of Mercury, the modelling of the non-gravitational acceleration is quite difficult, while, with the use of ISA accelerometer we are able to gain a factor 100 in accuracy. In this brief paper we will focus on the characteristics of the ISA accelerometer, on its positioning on-board the MPO and in particularly to the techniques for on ground calibration, avoiding the effects of the Earth gravity.

  4. Analysis of Static Spacecraft Floating Potential at Low Earth Orbit (LEO) (United States)

    Herr, Joel L.; Hwang, K. S.; Wu, S. T.


    Spacecraft floating potential is the charge on the external surfaces of orbiting spacecraft relative to the space. Charging is caused by unequal negative and positive currents to spacecraft surfaces. The charging process continues until the accelerated particles can be collected rapidly enough to balance the currents at which point the spacecraft has reached its equilibrium or floating potential. In low inclination. Low Earth Orbit (LEO), the collection of positive ion and negative electrons. in a particular direction. are typically not equal. The level of charging required for equilibrium to be established is influenced by the characteristics of the ambient plasma environment. by the spacecraft motion, and by the geometry of the spacecraft. Using the kinetic theory, a statistical approach for studying the interaction is developed. The approach used to study the spacecraft floating potential depends on which phenomena are being applied. and on the properties of the plasma. especially the density and temperature. The results from kinetic theory derivation are applied to determine the charging level and the electric potential distribution at an infinite flat plate perpendicular to a streaming plasma using finite-difference scheme.

  5. Traverses for lunar rovers and sample return teleoperated from Earth or cislunar orbit (United States)

    Kamps, Oscar; Foing, Bernard H.; Flahaut, Jessica


    Most interesting sites for exploration are near the poles of the Moon where water and other ices and volatiles could be stable in the permanent shaded regions. Several instruments on multiple orbiters have indicated the presence of hydrogen or hydration but the relation with the illumination conditions are not as clear. Which other variables are involved to trap water near the poles is not known. This ignorance makes it of high interest to do in-situ research on the Moon. ESA, NASA and other agencies are studying a teleoperated mission from cislunar orbit with Orion (eg. HERACLES international lunar exploration architecture) with the possibility of long rover traverses, and human assisted sample return. This mission concept was used for this study on a rover traverse. This study focuses on both the North as South Pole. The site selection for a traverse was based on the temperature map from Diviner. Regions of interests were made as primary selection and cover areas where the maximum temperature is lower than the sublimation temperature of CO2. Data from neutron spectrometer from the Prospector, and crater epoch according to the USGS were used to make a selection of regions of interest. These selected sites where studied on their accessibility for a rover, based on the slope map made from the LOLA elevation model. A landing site was selected based on assumptions that it should be at least one kilometre in diameter and have a slope lower than 5 degrees. The temperature difference (Tmax-Tmin from the Diviner measurements) was used select a scientifically interesting site between the landing site and destination inside a PSR. It was thought that a site with a temperature difference larger than 150K is interesting to study volatile migration processes. Eventually for the traverse planning a tool in ArcGIS was used which calculates the easiest from one location to another where the slope is used as limiting factor. We give the example study of rover traverse planning


    Energy Technology Data Exchange (ETDEWEB)

    Brown, Robert A., E-mail: [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)


    We use N{sub t} , the number of exoplanets observed in time t, as a science metric to study direct-search missions like Terrestrial Planet Finder. In our model, N has 27 parameters, divided into three categories: 2 astronomical, 7 instrumental, and 18 science-operational. For various ''27-vectors'' of those parameters chosen to explore parameter space, we compute design reference missions to estimate N{sub t} . Our treatment includes the recovery of completeness c after a search observation, for revisits, solar and antisolar avoidance, observational overhead, and follow-on spectroscopy. Our baseline 27-vector has aperture D = 16 m, inner working angle IWA = 0.039'', mission time t = 0-5 yr, occurrence probability for Earth-like exoplanets η = 0.2, and typical values for the remaining 23 parameters. For the baseline case, a typical five-year design reference mission has an input catalog of ∼4700 stars with nonzero completeness, ∼1300 unique stars observed in ∼2600 observations, of which ∼1300 are revisits, and it produces N {sub 1} ∼ 50 exoplanets after one year and N {sub 5} ∼ 130 after five years. We explore offsets from the baseline for 10 parameters. We find that N depends strongly on IWA and only weakly on D. It also depends only weakly on zodiacal light for Z < 50 zodis, end-to-end efficiency for h > 0.2, and scattered starlight for ζ < 10{sup –10}. We find that observational overheads, completeness recovery and revisits, solar and antisolar avoidance, and follow-on spectroscopy are all important factors in estimating N.

  7. The ESA-JAXA EarthCARE clouds, aerosol and radiation explorer mission: overview and development status (United States)

    Lajas, Dulce; Eisinger, M.; Wehr, T.; Koopman, Robert; Lefebvre, A.


    The EarthCARE, Earth Clouds, Aerosol and Radiation Explorer, is a joint European-Japanese mission (ESA/JAXA/NICT) which has been defined with the objective of improving the understanding of cloud-aerosol-radiation interactions so as to include them correctly and reliably in climate and numerical weather prediction models. The EarthCARE Mission has been approved for implementation as ESA's third Earth Explorer Core Mission. It is currently in its Detailed Design Phase (phase C/D) with a launch scheduled for 2018 [1]. This paper presents the EarthCARE programmatic status, the current instrument design and mission performance. The mission end-to-end simulator (E3SIM) and data processing up to level 2 (geophysical products) and related science activities will be discussed. The E3SIM supports end-to-end simulations from a scene definition to synergistic level 2 products. Level 2 retrieval algorithms can be tested in the full chain (provision of input data, algorithm performance tests by comparison of outputs with known inputs) by using a single framework with well-defined interfaces helping to harmonise algorithm developments.

  8. Understanding the Sun-Earth Libration Point Orbit Formation Flying Challenges For WFIRST and Starshade (United States)

    Webster, Cassandra M.; Folta, David C.


    In order to fly an occulter in formation with a telescope at the Sun-Earth L2 (SEL2) Libration Point, one must have a detailed understanding of the dy-namics that govern the restricted three body system. For initial purposes, a linear approximation is satisfactory, but operations will require a high-fidelity modeling tool along with strategic targeting methods in order to be successful. This paper focuses on the challenging dynamics of the transfer trajectories to achieve the relative positioning of two spacecraft to fly in formation at SEL2, in our case, the Wide-Field Infrared Survey Telescope (WFIRST) and a proposed Starshade. By modeling the formation transfers using a high fidelity tool, an accurate V approximation can be made to as-sist with the development of the subsystem design required for a WFIRST and Starshade formation flight mission.

  9. Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation. (United States)

    Djordjevic, Ivan B


    In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM.

  10. Anaphylaxis, Intra-Abdominal Infections, Skin Lacerations, and Behavioral Emergencies: A Literature Review of Austere Analogs for a near Earth Asteroid Mission (United States)

    Chough, Natacha G.; Watkins, Sharmi; Menon, Anil S.


    As space exploration is directed towards destinations beyond low-Earth orbit, the consequent new set of medical risks will drive requirements for new capabilities and more resources to ensure crew health. The Space Medicine Exploration Medical Conditions List (SMEMCL), developed by the Exploration Medical Capability element of the Human Research Program, addresses the risk of "unacceptable health and mission outcomes due to limitations of in-flight medical capabilities". It itemizes 85 evidence-based clinical requirements for eight different mission profiles and identifies conditions warranting further research and technology development. Each condition is given a clinical priority for each mission profile. Four conditions -- intra-abdominal infections, skin lacerations, anaphylaxis, and behavioral emergencies -- were selected as a starting point for analysis. A systematic literature review was performed to understand how these conditions are treated in austere, limited-resource, space-analog environments (i.e., high-altitude and mountain environments, submarines, military deployments, Antarctica, isolated wilderness environments, in-flight environments, and remote, resource-poor, rural environments). These environments serve as analogs to spaceflight because of their shared characteristics (limited medical resources, delay in communication, confined living quarters, difficulty with resupply, variable time to evacuation). Treatment of these four medical conditions in austere environments provides insight into medical equipment and training requirements for exploration-class missions.

  11. The EnMAP Spaceborne Imaging Spectroscopy Mission for Earth Observation

    Directory of Open Access Journals (Sweden)

    Luis Guanter


    Full Text Available Imaging spectroscopy, also known as hyperspectral remote sensing, is based on the characterization of Earth surface materials and processes through spectrally-resolved measurements of the light interacting with matter. The potential of imaging spectroscopy for Earth remote sensing has been demonstrated since the 1980s. However, most of the developments and applications in imaging spectroscopy have largely relied on airborne spectrometers, as the amount and quality of space-based imaging spectroscopy data remain relatively low to date. The upcoming Environmental Mapping and Analysis Program (EnMAP German imaging spectroscopy mission is intended to fill this gap. An overview of the main characteristics and current status of the mission is provided in this contribution. The core payload of EnMAP consists of a dual-spectrometer instrument measuring in the optical spectral range between 420 and 2450 nm with a spectral sampling distance varying between 5 and 12 nm and a reference signal-to-noise ratio of 400:1 in the visible and near-infrared and 180:1 in the shortwave-infrared parts of the spectrum. EnMAP images will cover a 30 km-wide area in the across-track direction with a ground sampling distance of 30 m. An across-track tilted observation capability will enable a target revisit time of up to four days at the Equator and better at high latitudes. EnMAP will contribute to the development and exploitation of spaceborne imaging spectroscopy applications by making high-quality data freely available to scientific users worldwide.

  12. A Plasma Aerocapture and Entry System for Manned Missions and Planetary Deep Space Orbiters Project (United States)

    National Aeronautics and Space Administration — The Plasma Magnetoshell is based on demonstrated experimental results and the successful implementation would dramatically decrease mission risk, launch cost, mass,...

  13. Detection, identification, and classification of mosquito larval habitats using remote sensing scanners in earth-orbiting satellites* (United States)

    Hayes, Richard O.; Maxwell, Eugene L.; Mitchell, Carl J.; Woodzick, Thomas L.


    A method of identifying mosquito larval habitats associated with fresh-water plant communities, wetlands, and other aquatic locations at Lewis and Clark Lake in the states of Nebraska and South Dakota, USA, using remote sensing imagery obtained by multispectral scanners aboard earth-orbiting satellites (Landsat 1 and 2) is described. The advantages and limitations of this method are discussed. PMID:2861917

  14. Van Allen Probes Mission Space Academy: Educating middle school students about Earth's mysterious radiation belts (United States)

    Butler, L.; Turney, D.; Matiella Novak, A.; Smith, D.; Simon, M.


    How's the weather in space? Why on Earth did NASA send two satellites above Earth to study radiation belts and space weather? To learn the answer to questions about NASA's Van Allen Probes mission, 450 students and their teachers from Maryland middle schools attended Space Academy events highlighting the Van Allen Probes mission. Sponsored by the Applied Physics Laboratory (APL) and Discovery Education, the events are held at the APL campus in Laurel, MD. Space Academies take students and teachers on behind-the-scenes exploration of how spacecraft are built, what they are designed to study, and introduces them to the many professionals that work together to create some of NASA's most exciting projects. Moderated by a public relations representative in the format of an official NASA press conference, the daylong event includes a student press conference with students as reporters and mission experts as panelists. Lunch with mission team members gives students a chance to ask more questions. After lunch, students don souvenir clean room suits, enjoy interactive science demonstrations, and tour APL facilities where the Van Allen Probes were built and tested before launch. Students may even have an opportunity to peek inside a clean room to view spacecraft being assembled. Prior to the event, teachers are provided with classroom activities, lesson plans, and videos developed by APL and Discovery Education to help prepare students for the featured mission. The activities are aligned to National Science Education Standards and appropriate for use in the classroom. Following their visit, student journalists are encouraged to write a short article about their field trip; selections are posted on the Space Academy web site. Designed to engage, inspire, and influence attitudes about space science and STEM careers, Space Academies provide an opportunity to attract underserved populations and emphasize that space science is for everyone. Exposing students to a diverse group of

  15. Bimodal Nuclear Thermal Rocket Sizing and Trade Matrix for Lunar, Near Earth Asteroid and Mars Missions (United States)

    McCurdy, David R.; Krivanek, Thomas M.; Roche, Joseph M.; Zinolabedini, Reza


    The concept of a human rated transport vehicle for various near earth missions is evaluated using a liquid hydrogen fueled Bimodal Nuclear Thermal Propulsion (BNTP) approach. In an effort to determine the preliminary sizing and optimal propulsion system configuration, as well as the key operating design points, an initial investigation into the main system level parameters was conducted. This assessment considered not only the performance variables but also the more subjective reliability, operability, and maintainability attributes. The SIZER preliminary sizing tool was used to facilitate rapid modeling of the trade studies, which included tank materials, propulsive versus an aero-capture trajectory, use of artificial gravity, reactor chamber operating pressure and temperature, fuel element scaling, engine thrust rating, engine thrust augmentation by adding oxygen to the flow in the nozzle for supersonic combustion, and the baseline turbopump configuration to address mission redundancy and safety requirements. A high level system perspective was maintained to avoid focusing solely on individual component optimization at the expense of system level performance, operability, and development cost.

  16. Human Missions to Mars Orbit, Phobos, and Mars Surface Using 100-kWe-Class Solar Electric Propulsion (United States)

    Price, Humphrey W.; Woolley, Ryan C.; Strange, Nathan J.; Baker, John D.


    Solar electric propulsion (SEP) tugs in the 100-kWe range, may be utilized to preposition cargo in the Mars system to enable more affordable human missions to Phobos and to the surface of Mars. The SEP tug, a high heritage follow-on to the 50-kWe SEP spacecraft proposed for the Asteroid Redirect Robotic Mission (ARRM), would have the same structure, tankage, electric propulsion components, and avionics as the ARRM version, But with double the number of solar arrays, Hall thrusters, and power processor units (PPUs) and would be accommodated within the same launch envelope defined for ARRM. As a feasibility study, a 950-day human mission to Phobos using a conjunction class trajectory, such as the 2033 opportunity, was developed using two 100-kWe SEP vehicles to preposition a habitat at Phobos and propulsion stages in high Mars orbit (HMO). An architecture concept for a crewed Mars surface lander mission was also developed as a reference to build on the Phobos mission architecture, adding a lander element that could be delivered using chemical propulsion and aerocapture.

  17. Shuttle Imaging Radar-C mission operations - Technology test bed for Earth Observing System synthetic aperture radar (United States)

    Trimble, J. P.; Collins, C. E.


    The mission operations for the Space Radar Lab (SRL), particularly in the areas of real-time replanning and science activity coordination, are presented. The two main components of SRL are the Shuttle Imaging Radar-C and the X-Band Synthetic Aperture Radar. The Earth Observing System SAR will be a multispectral, multipolarization radar satellite that will provide information over an entire decade, permitting scientists to monitor large-scale changes in the earth's environment over a long period of time.

  18. Atmosphere Kits: Hands-On Learning Activities with a Foundation in NASA Earth Science Missions. (United States)

    Teige, V.; McCrea, S.; Damadeo, K.; Taylor, J.; Lewis, P. M., Jr.; Chambers, L. H.


    The Science Directorate (SD) at NASA Langley Research Center provides many opportunities to involve students, faculty, researchers, and the citizen science community in real world science. The SD Education Team collaborates with the education community to bring authentic Earth science practices and real-world data into the classroom, provide the public with unique NASA experiences, engaging activities, and advanced technology, and provide products developed and reviewed by science and education experts. Our goals include inspiring the next generation of Science, Technology, Engineering and Mathematics (STEM) professionals and improving STEM literacy by providing innovative participation pathways for educators, students, and the public. The SD Education Team has developed Atmosphere activity kits featuring cloud and aerosol learning activities with a foundation in NASA Earth Science Missions, the Next Generation Science Standards, and The GLOBE Program's Elementary Storybooks. Through cloud kit activities, students will learn how to make estimates from observations and how to categorize and classify specific cloud properties, including cloud height, cloud cover, and basic cloud types. The purpose of the aerosol kit is to introduce students to aerosols and how they can affect the colors we see in the sky. Students will engage in active observation and reporting, explore properties of light, and model the effects of changing amounts/sizes or aerosols on sky color and visibility. Learning activity extensions include participation in ground data collection of environmental conditions and comparison and analysis to related NASA data sets, including but not limited to CERES, CALIPSO, CloudSat, and SAGE III on ISS. This presentation will provide an overview of multiple K-6 NASA Earth Science hands-on activities and free resources will be available.

  19. SWOT: The Surface Water and Ocean Topography Mission. Wide- Swath Altimetric Elevation on Earth (United States)

    Fu, Lee-Lueng (Editor); Alsdorf, Douglas (Editor); Morrow, Rosemary; Rodriguez, Ernesto; Mognard, Nelly


    The elevation of the surface of the ocean and freshwater bodies on land holds key information on many important processes of the Earth System. The elevation of the ocean surface, called ocean surface topography, has been measured by conventional nadirlooking radar altimeter for the past two decades. The data collected have been used for the study of large-scale circulation and sea level change. However, the spatial resolution of the observations has limited the study to scales larger than about 200 km, leaving the smaller scales containing substantial kinetic energy of ocean circulation that is responsible for the flux of heat, dissolved gas and nutrients between the upper and the deep ocean. This flux is important to the understanding of the ocean's role in regulatingfuture climate change.The elevation of the water bodies on land is a key parameter required for the computation of storage and discharge of freshwater in rivers, lakes, and wetlands. Globally, the spatial and temporal variability of water storage and discharge is poorly known due to the lack of well-sampled observations. In situ networks measuring river flows are declining worldwide due to economic and political reasons. Conventional altimeter observations suffers from the complexity of multiple peaks caused by the reflections from water, vegetation canopy and rough topography, resulting in much less valid data over land than over the ocean. Another major limitation is the large inter track distance preventing good coverage of rivers and other water bodies.This document provides descriptions of a new measurement technique using radar interferometry to obtain wide-swath measurement of water elevation at high resolution over both the ocean and land. Making this type of measurement, which addresses the shortcomings of conventional altimetry in both oceanographic and hydrologic applications, is the objective of a mission concept called Surface Water and Ocean Topography (SWOT), which was recommended by

  20. Orbital maneuvers and space rendezvous (United States)

    Butikov, Eugene I.


    Several possibilities of launching a space vehicle from the orbital station are considered and compared. Orbital maneuvers discussed in the paper can be useful in designing a trajectory for a specific space mission. The relative motion of orbiting bodies is investigated on examples of spacecraft rendezvous with the space station that stays in a circular orbit around the Earth. An elementary approach is illustrated by an accompanying simulation computer program and supported by a mathematical treatment based on fundamental laws of physics and conservation laws. Material is appropriate for engineers and other personnel involved in space exploration, undergraduate and graduate students studying classical physics and orbital mechanics.

  1. The Characterization of Non-Gravitational Perturbations That Act on Near-Earth Asteroid Orbits (United States)

    Margot, Jean-Luc; Greenberg, Adam H.; Verma, Ashok K.; Taylor, Patrick A.


    The Yarkovsky effect is a thermal process acting upon the orbits of small celestial bodies which can cause these orbits to slowly expand or contract with time. The effect is subtle -- typical drift rates lie near 1e-4 au/My for a ~1 km diameter object -- and is thus generally difficult to measure. However, objects with long observation intervals, as well as objects with radar detections, serve as excellent candidates for the observation of this effect.We analyzed both optical and radar astrometry for all numbered Near-Earth Asteroids (NEAs), as well as several un-numbered NEAs. In order to quantify the likelihood of Yarkovsky detections, we developed a metric based on the quality of Yarkovsky fits as compared to that of gravity-only fits. Based on the metric results, we report 167 objects with measured Yarkovsky drifts.Our Yarkovsky sample is the largest published set of such detections, and presents an opportunity to examine the physical properties of these NEAs and the Yarkovsky effect in a statistical manner. In particular, we confirm the Yarkovsky effect's theoretical size dependence of 1/D, where D is diameter. We also examine the efficiency with which this effect converts absorbed light into orbital drift. Using our set of 167 objects, we find typical efficiences of around 5%. This efficiency can be used to place bounds on spin and thermal properties. We report the ratio of positive to negative drift rates and interpret this ratio in terms of prograde/retrograde rotators and main belt escape mechanisms. The observed ratio has a probability of 1 in 9 million of occurring by chance, which confirms the presence of a non-gravitational influence. We examine how the presence of radar data affect the strength and precision of our detections. We find that, on average, the precision of radar+optical detections improves by a factor of approximately 1.6 for each additional apparition with ranging data compared to that of optical-only solutions.

  2. 800 x 800 charge-coupled device /CCD/ camera for the Galileo Jupiter Orbiter mission (United States)

    Clary, M. C.; Klaasen, K. P.; Snyder, L. M.; Wang, P. K.


    During January 1982 the NASA space transportation system will launch a Galileo spacecraft composed of an orbiting bus and an atmospheric entry probe to arrive at the planet Jupiter in July 1985. A prime element of the orbiter's scientific instrument payload will be a new generation slow-scan planetary imaging system based on a newly developed 800 x 800 charge-coupled device (CCD) image sensor. Following Jupiter orbit insertion, the single, narrow-angle, CCD camera, designated the Solid State Imaging (SSI) Subsystem, will operate for 20 months as the orbiter makes repeated encounters with Jupiter and its Galilean Satellites. During this period the SSI will acquire 40,000 images of Jupiter's atmosphere and the surfaces of the Galilean Satellites. This paper describes the SSI, its operational modes, and science objectives.

  3. Ocean Surface Topography Mission (OSTM) /Jason-2: Orbital Information (NODC Accession 0044985) (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains the descriptions for the OSTM/Jason-2 orbital information, which is served through the NOAA/NESDIS Comprehensive Large Array-data Stewardship...

  4. Framework for Processing Citizens Science Data for Applications to NASA Earth Science Missions (United States)

    Teng, William; Albayrak, Arif


    Citizen science (or crowdsourcing) has drawn much high-level recent and ongoing interest and support. It is poised to be applied, beyond the by-now fairly familiar use of, e.g., Twitter for natural hazards monitoring, to science research, such as augmenting the validation of NASA earth science mission data. This interest and support is seen in the 2014 National Plan for Civil Earth Observations, the 2015 White House forum on citizen science and crowdsourcing, the ongoing Senate Bill 2013 (Crowdsourcing and Citizen Science Act of 2015), the recent (August 2016) Open Geospatial Consortium (OGC) call for public participation in its newly-established Citizen Science Domain Working Group, and NASA's initiation of a new Citizen Science for Earth Systems Program (along with its first citizen science-focused solicitation for proposals). Over the past several years, we have been exploring the feasibility of extracting from the Twitter data stream useful information for application to NASA precipitation research, with both "passive" and "active" participation by the twitterers. The Twitter database, which recently passed its tenth anniversary, is potentially a rich source of real-time and historical global information for science applications. The time-varying set of "precipitation" tweets can be thought of as an organic network of rain gauges, potentially providing a widespread view of precipitation occurrence. The validation of satellite precipitation estimates is challenging, because many regions lack data or access to data, especially outside of the U.S. and in remote and developing areas. Mining the Twitter stream could augment these validation programs and, potentially, help tune existing algorithms. Our ongoing work, though exploratory, has resulted in key components for processing and managing tweets, including the capabilities to filter the Twitter stream in real time, to extract location information, to filter for exact phrases, and to plot tweet distributions. The

  5. The Cost of Jointness: Insights from Environmental Monitoring Systems in Low-Earth Orbit

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, Morgan Maeve [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    This report summarizes the results of doctoral research that explored the cost impact of acquiring complex government systems jointly. The report begins by reviewing recent evidence that suggests that joint programs experience greater cost growth than non-joint programs. It continues by proposing an alternative approach for studying cost growth on government acquisition programs and demonstrates the utility of this approach by applying it to study the cost of jointness on three past programs that developed environmental monitoring systems for low-Earth orbit. Ultimately, the report concludes that joint programs' costs grow when the collaborating government agencies take action to retain or regain their autonomy. The report provides detailed qualitative and quantitative data in support of this conclusion and generalizes its findings to other joint programs that were not explicitly studied here. Finally, it concludes by presenting a quantitative model that assesses the cost impacts of jointness and by demonstrating how government agencies can more effectively architect joint programs in the future.

  6. Near-Earth asteroid satellite spins under spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Naidu, Shantanu P.; Margot, Jean-Luc [Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095 (United States)


    We develop a fourth-order numerical integrator to simulate the coupled spin and orbital motions of two rigid bodies having arbitrary mass distributions under the influence of their mutual gravitational potential. We simulate the dynamics of components in well-characterized binary and triple near-Earth asteroid systems and use surface of section plots to map the possible spin configurations of the satellites. For asynchronous satellites, the analysis reveals large regions of phase space where the spin state of the satellite is chaotic. For synchronous satellites, we show that libration amplitudes can reach detectable values even for moderately elongated shapes. The presence of chaotic regions in the phase space has important consequences for the evolution of binary asteroids. It may substantially increase spin synchronization timescales, explain the observed fraction of asychronous binaries, delay BYORP-type evolution, and extend the lifetime of binaries. The variations in spin rate due to large librations also affect the analysis and interpretation of light curve and radar observations.

  7. Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (United States)

    Bank, Bruce A.; de Groh, Kim K.; Backus, Jane A.


    A predictive tool was developed to estimate the low Earth orbit (LEO) atomic oxygen erosion yield of polymers based on the results of the Polymer Erosion and Contamination Experiment (PEACE) Polymers experiment flown as part of the Materials International Space Station Experiment 2 (MISSE 2). The MISSE 2 PEACE experiment accurately measured the erosion yield of a wide variety of polymers and pyrolytic graphite. The 40 different materials tested were selected specifically to represent a variety of polymers used in space as well as a wide variety of polymer chemical structures. The resulting erosion yield data was used to develop a predictive tool which utilizes chemical structure and physical properties of polymers that can be measured in ground laboratory testing to predict the in-space atomic oxygen erosion yield of a polymer. The properties include chemical structure, bonding information, density and ash content. The resulting predictive tool has a correlation coefficient of 0.914 when compared with actual MISSE 2 space data for 38 polymers and pyrolytic graphite. The intent of the predictive tool is to be able to make estimates of atomic oxygen erosion yields for new polymers without requiring expensive and time consumptive in-space testing.

  8. The detection of ultra-relativistic electrons in low Earth orbit (United States)

    Katsiyannis, Athanassios C.; Dominique, Marie; Pierrard, Viviane; Rosson, Graciela Lopez; Keyser, Johan De; Berghmans, David; Kruglanski, Michel; Dammasch, Ingolf E.; Donder, Erwin De


    Aims: To better understand the radiation environment in low Earth orbit (LEO), the analysis of in-situ observations of a variety of particles, at different atmospheric heights, and in a wide range of energies, is needed. Methods: We present an analysis of energetic particles, indirectly detected by the large yield radiometer (LYRA) instrument on board ESA's project for on-board autonomy 2 (PROBA2) satellite as background signal. Combining energetic particle telescope (EPT) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV. Results: The observed events are strongly correlated to geo-magnetic activity and appear even during modest disturbances. They are also well confined geographically within the L = 4-6 McIlwain zone, which makes it possible to identify their source. Conclusions: Although highly energetic particles are commonly perturbing data acquisition of space instruments, we show in this work that ultra-relativistic electrons with energies in the range of 2-8 MeV are detected only at high latitudes, while not present in the South Atlantic Anomaly region.

  9. Evaluation of Aerodynamic Drag and Torque for External Tanks in Low Earth Orbit. (United States)

    Stone, William C; Witzgall, Christoph


    A numerical procedure is described in which the aerodynamic drag and torque in low Earth orbit are calculated for a prototype Space Shuttle external tank and its components, the "LO2" and "LH2" tanks, carrying liquid oxygen and hydrogen, respectively, for any given angle of attack. Calculations assume the hypersonic limit of free molecular flow theory. Each shell of revolution is assumed to be described by a series of parametric equations for their respective contours. It is discretized into circular cross sections perpendicular to the axis of revolution, which yield a series of ellipses when projected according to the given angle of attack. The drag profile, that is, the projection of the entire shell is approximated by the convex envelope of those ellipses. The area of the drag profile, that is, the drag area, and its center of area moment, that is, the drag center, are then calculated and permit determination of the drag vector and the eccentricity vector from the center of gravity of the shell to the drag center. The aerodynamic torque is obtained as the cross product of those vectors. The tanks are assumed to be either evacuated or pressurized with a uniform internal gas distribution: dynamic shifting of the tank center of mass due to residual propellant sloshing is not considered.

  10. Simulation of major space particles toward selected materials in a near-equatorial low earth orbit (United States)

    Suparta, Wayan; Zulkeple, Siti Katrina


    A low earth orbit near the equator (LEO-NEqO) is exposed to the highest energies from galactic cosmic rays (GCR) and from trapped protons with a wide range of energies. Moreover, GCR fluxes were seen to be the highest in 2009 to 2010 when communication belonging to the RazakSAT-1 satellite was believed to have been lost. Hence, this study aimed to determine the influence of the space environment toward the operation of LEO-NEqO satellites by investigating the behavior of major space particles toward satellite materials. The space environment was referred to GCR protons and trapped protons. Their fluxes were obtained from the Space Environment Information System (SPENVIS) and their tracks were simulated through three materials using a simulation program called Geometry and Tracking (Geant4). The materials included aluminum (Al), gallium arsenide (GaAs) and silicon (Si). Then the total ionizing dose (TID) and non-ionizing dose (NIEL) were calculated for a three-year period. Simulations showed that GCR traveled at longer tracks and produced more secondary radiation than trapped protons. Al turned out to receive the lowest total dose, while GaAs showed to be susceptible toward GCR than Si. However, trapped protons contributed the most in spacecraft doses where Si received the highest doses. Finally, the comparison between two Geant4 programs revealed the estimated doses differed at <18%.

  11. Radiation Protection Effectiveness of Polymeric Based Shielding Materials at Low Earth Orbit (United States)

    Badavi, Francis F.; Stewart-Sloan, Charlotte R.; Wilson, John W.; Adams, Daniel O.


    Correlations of limited ionizing radiation measurements onboard the Space Transportation System (STS; shuttle) and the International Space Station (ISS) with numerical simulations of charged particle transport through spacecraft structure have indicated that usage of hydrogen rich polymeric materials improves the radiation shielding performance of space structures as compared to the traditionally used aluminum alloys. We discuss herein the radiation shielding correlations between measurements on board STS-81 (Atlantis, 1997) using four polyethylene (PE) spheres of varying radii, and STS-89 (Endeavour, 1998) using aluminum alloy spheres; with numerical simulations of charged particle transport using the Langley Research Center (LaRC)-developed High charge (Z) and Energy TRaNsport (HZETRN) algorithm. In the simulations, the Galactic Cosmic Ray (GCR) component of the ionizing radiation environment at Low Earth Orbit (LEO) covering ions in the 1albedo neutron environment resulting from interaction of GCR ions with upper atmosphere is modeled through extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. With the validity of numerical simulations through correlation with PE and aluminum spheres measurements established, we further present results from the expansion of the simulations through the selection of high hydrogen content commercially available polymeric constituents such as PE foam core and Spectra fiber(Registered TradeMark) composite face sheet to assess their radiation shield properties as compared to generic PE.

  12. Filament wound metal lined propellant tanks for future Earth-to-orbit transports (United States)

    Macconochie, Ian O.; Davis, Robert B.; Freeman, William T., Jr.


    For future Earth-to-orbit transport vehicles, reusability and lighter weights are sought for the main propellant tanks. To achieve this, a filament wound tank with a metal liner and an intermediate layer of foam-filled honeycomb is proposed. A hydrogen tank is used as an example. To accommodate mismatches in the expansion of liner and overwrap a design is proposed wherin the liner is configured so that the extension of the liner under pressure matches the expected contraction of the same liner due to the presence of a cryogen. In operation, the liner is pressurized at a rate such that the pressure strain matches the contraction due to decrease in temperature. As an alternate approach, compressive pre-stress is placed in the liner such that it will not separate from the overwrap. A finite element program is used to show stresses in the liner and overwrap for various tank pressures for the pre-stressed liner concept. A fracture mechanics analysis is made of the liners to determine tank life. The tank concept shown has a similar weight to the Shuttle external hydrogen tank, but the filament wound tank is expected to be reusable. Integration of the propellant tanks into a future transport vehicle is discussed.

  13. The viscoelastic characterization of polymer materials exposed to the low-Earth orbit environment (United States)

    Strganac, Thomas; Letton, Alan


    Recent accomplishments in our research efforts have included the successful measurement of the thermal mechanical properties of polymer materials exposed to the low-earth orbit environment. In particular, viscoelastic properties were recorded using the Rheometrics Solids Analyzer (RSA 2). Dynamic moduli (E', the storage component of the elastic modulus, and E'', the loss component of the elastic modulus) were recorded over three decades of frequency (0.1 to 100 rad/sec) for temperatures ranging from -150 to 150 C. Although this temperature range extends beyond the typical use range of the materials, measurements in this region are necessary in the development of complete viscoelastic constitutive models. The experimental results were used to provide the stress relaxation and creep compliance performance characteristics through viscoelastic correspondence principles. Our results quantify the differences between exposed and control polymer specimens. The characterization is specifically designed to elucidate a constitutive model that accurately predicts the change in behavior of these materials due to exposure. The constitutive model for viscoelastic behavior reflects the level of strain, the rate of strain, and the history of strain as well as the thermal history of the material.

  14. A Mobile Asteroid Surface Scout (MASCOT) on board the Hayabusa 2 Mission to the near Earth asteroid (162173) Ryugu (United States)

    Jaumann, R.; Bibring, J. P.; Glassmeier, K. H.; Grott, M.; Ho, T. M.; Ulamec, S.; Schmitz, N.; Auster, H. U.; Biele, J.; Kuninaka, H.; Okada, T.; Yoshikawa, M.; Watanabe, S.; Spohn, T.; Koncz, A.; Hercik, D.; Michaelis, H.; Fujimoto, M.


    MASCOT is part of JAXA's Hayabusa 2 asteroid sample return mission that has been launched to asteroid (162173) Ryugu (1,2,3) on Dec 3rd, 2014. It is scheduled to arrive at Ryugu in 2018, and return samples to Earth in 2020. The German Aerospace Center (DLR) developed the lander MASCOT with contributions from CNES (France) (2,3). Ryugu has been classified as a Cg-type (4), believed to be a primitive volatile-rich remnant from the early solar system. Its visible geometric albedo is 0.07±0.01with a diameter of 0.87±0.03 km (5). The thermal inertia indicates thick dust with a cm-sized, gravel-dominated surface layer (5,6). Ryugu shows a retrograde rotation with a period of 7.63±0.01h. Spectral observations indicate iron-bearing phyllosilicates (1) on parts of the surface, suggesting compositional heterogeneity. MASCOT will enable to in-situ map the asteroid's geomorphology, the intimate structure, texture and composition of the regolith (dust, soil and rocks), and its thermal, mechanical, and magnetic properties in order to provide ground truth for the orbiter remote measurements, support the selection of sampling sites, and provide context information for the returned samples (2,3). MASCOT comprises a payload of four scientific instruments: camera, radiometer, magnetometer and hyperspectral microscope (2,3). Characterizing the properties of asteroid regolith in-situ will deliver important ground truth for further understanding telescopic and orbital observations as well as samples of asteroids. MASCOT will descend and land on the asteroid and will change its position by hopping (3). (1) Vilas, F., Astro. J. 1101-1105, 2008; (2) Jaumann, R., et al., SSR, DOI 10.1007/s11214-016-0263-2, 2016; (3) Ho, T.-M. et al., SSR, DOI 10.1007/s11214-016-0251-6, 2016; (4) Bus, S.J., Binzel, R.P. Icarus 158, 2002; (5) Hasegawa, T.G., et al., Astron. Soc. Japan 60, 2008; (6) T.G. Müller, T.G., et al., doi 10.1051/0004-6361/201015599, 2011.

  15. Attitude and orbital dynamics modeling for an uncontrolled solar-sail experiment in low-Earth orbit

    NARCIS (Netherlands)

    Pirovano, L.; Seefeldt, P.; Dachwald, B.; Noomen, R.


    Gossamer-1 is the first project of the three-step Gossamer roadmap, the purpose of which is to develop, prove and demonstrate that solar-sail technology is a safe and reliable propulsion technique for long-lasting and high-energy missions. This paper firstly presents the structural analysis

  16. The Asteroid Redirect Mission (ARM) (United States)

    Abell, P. A.; Mazanek, D. D.; Reeves, D. M.; Chodas, P. W.; Gates, M. M.; Johnson, L. N.; Ticker, R. L.


    To achieve its long-term goal of sending humans to Mars, the National Aeronautics and Space Administration (NASA) plans to proceed in a series of incrementally more complex human spaceflight missions. Today, human flight experience extends only to Low-Earth Orbit (LEO), and should problems arise during a mission, the crew can return to Earth in a matter of minutes to hours. The next logical step for human spaceflight is to gain flight experience in the vicinity of the Moon. These cis-lunar missions provide a "proving ground" for the testing of systems and operations while still accommodating an emergency return path to the Earth that would last only several days. Cis-lunar mission experience will be essential for more ambitious human missions beyond the Earth- Moon system, which will require weeks, months, or even years of transit time.

  17. A Low Cost Automatic Detection and Ranging System for Space Surveillance in the Medium Earth Orbit Region and Beyond (United States)

    Danescu, Radu; Ciurte, Anca; Turcu, Vlad


    The space around the Earth is filled with man-made objects, which orbit the planet at altitudes ranging from hundreds to tens of thousands of kilometers. Keeping an eye on all objects in Earth's orbit, useful and not useful, operational or not, is known as Space Surveillance. Due to cost considerations, the space surveillance solutions beyond the Low Earth Orbit region are mainly based on optical instruments. This paper presents a solution for real-time automatic detection and ranging of space objects of altitudes ranging from below the Medium Earth Orbit up to 40,000 km, based on two low cost observation systems built using commercial cameras and marginally professional telescopes, placed 37 km apart, operating as a large baseline stereovision system. The telescopes are pointed towards any visible region of the sky, and the system is able to automatically calibrate the orientation parameters using automatic matching of reference stars from an online catalog, with a very high tolerance for the initial guess of the sky region and camera orientation. The difference between the left and right image of a synchronized stereo pair is used for automatic detection of the satellite pixels, using an original difference computation algorithm that is capable of high sensitivity and a low false positive rate. The use of stereovision provides a strong means of removing false positives, and avoids the need for prior knowledge of the orbits observed, the system being able to detect at the same time all types of objects that fall within the measurement range and are visible on the image. PMID:24521941

  18. Orbital (United States)

    Hanson, Robert M.


    ORBITAL requires the following software, which is available for free download from the Internet: Netscape Navigator, version 4.75 or higher, or Microsoft Internet Explorer, version 5.0 or higher; Chime Plug-in, version compatible with your OS and browser (available from MDL).

  19. Modulation of LISA free-fall orbits due to the Earth-Moon system

    Energy Technology Data Exchange (ETDEWEB)

    Cerdonio, Massimo; Marzari, Francesco [Department of Physics, University of Padova and INFN Padova, via Marzolo 8, I-35131 Padova (Italy); De Marchi, Fabrizio [Department of Physics, University of Trento and INFN Trento, I-38100 Povo (Trento) (Italy); De Pietri, Roberto [Department of Physics, University of Parma and INFN Parma I-43100 Parma (Italy); Jetzer, Philippe [Institute of Theoretical Physics, University of Zuerich, Winterhurerstrasse 190, 8057 Zuerich (Switzerland); Mazzolo, Giulio [Max Planck Institut fuer Gravitationsphysik, Callinstrasse 38, 30167 Hannover (Germany); Ortolan, Antonello [INFN Laboratori Nazionali di Legnaro, Viale dell' Universita 35020 Legnaro (Padova) (Italy); Sereno, Mauro, E-mail: fdemarchi@science.unitn.i [Dipartimento di Fisica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)


    We calculate the effect of the Earth-Moon (EM) system on the free-fall motion of LISA test masses. We show that the periodic gravitational pulling of the EM system induces a resonance with fundamental frequency 1 yr{sup -1} and a series of periodic perturbations with frequencies equal to integer harmonics of the synodic month ({approx_equal} 3.92 x 10{sup -7} Hz). We then evaluate the effects of these perturbations (up to the 6th harmonics) on the relative motions between each test mass couple, finding that they range between 3 mm and 10 pm for the 2nd and 6th harmonic, respectively. If we take the LISA sensitivity curve, as extrapolated down to 10{sup -6} Hz in Bender (2003 Class. Quantum Grav. 20 301-10), we obtain that a few harmonics of the EM system can be detected in the Doppler data collected by the LISA space mission. This suggests that the EM system gravitational near field could provide an additional crosscheck to the calibration of LISA, as extended to such low frequencies.

  20. Participating in Authentic Science with the Aid of Learning Progressions through Mission Earth Workshops (United States)

    Lewis, P. M., Jr.; Taylor, J.; Harte, T.; Czajkowski, K. P.


    "MISSION EARTH: Fusing GLOBE with NASA Assets to Build Systemic Innovation In STEM Education" is one of the new education cooperative agreements funded by the NASA Science Mission Directorate. Students will learn how to conduct "real science" through hands-on data collection using Global Learning and Observations to Benefit the Environment (GLOBE) protocols combined with other NASA science educational materials. This project aims to work with educators spanning the full K-12 range, requiring three grade bands of learning progressions and vertical alignment among materials and resources to best meet classroom needs. From K to 12 students have vastly different abilities to conduct and learn from scientific investigations. Hand-picked NASA assets will provide appropriate exposure across the curriculum and grade bands, and we are developing unique learning progressions that bring together GLOBE protocols for data collection and learning activities, NASA data sets through MY NASA DATA for data comparison, and more. The individual materials are not limited to science, but also include all elements of STEM with literacy components added in where appropriate. This will give the students an opportunity to work on better understanding the world around them in a well-rounded way, and offer cross-subject/classroom exposure to improve student understanding. To ensure that these learning progressions can continue to be used in the classroom in the future, alignment to the Next Generation Science Standards will help frame all of the materials and products. The learning progressions will be living documents that will change based on context. After several iterations, it is our goal to produce learning progressions for grades K-12 that will allow any STEM teacher to pick up and infuse NASA and GLOBE in their classroom at any location and at any time in their school year. This presentation will share results from the first year of development for this project.

  1. Integrated solution for the complete remote sensing process - Earth Observation Mission Control Centre (EOMC2) (United States)

    Czapski, Paweł


    We are going to show the latest achievements of the Remote Sensing Division of the Institute of Aviation in the area of remote sensing, i.e. the project of the integrated solution for the whole remote sensing process ranging from acquiring to providing the end user with required information. Currently, these tasks are partially performed by several centers in Poland, however there is no leader providing an integrated solution. Motivated by this fact, the Earth Observation Mission Control Centre (EOMC2) was established in the Remote Sensing Division of the Institute of Aviation that will provide such a comprehensive approach. Establishing of EOMC2 can be compared with creating Data Center Aerial and Satellite Data Centre (OPOLIS) in the Institute of Geodesy and Cartography in the mid-70s in Poland. OPOLIS was responsible for broadly defined data processing, it was a breakthrough innovation that initiated the use of aerial image analysis in Poland. Operation center is a part of the project that will be created, which in comparison with the competitors will provide better solutions, i.e.: • Centralization of the acquiring, processing, publishing and archiving of data, • Implementing elements of the INSPIRE directive recommendations on spatial data management, • Providing the end-user with information in the near real-time, • Ability of supplying the system with images of various origin (aerial, satellite, e.g. EUMETCast, Sentinel, Landsat) and diversity of telemetry data, data aggregation and using the same algorithms to images obtained from different sources, • System reconfiguration and batch processing of large data sets at any time, • A wide range of potential applications: precision agriculture, environmental protection, crisis management and national security, aerial, small satellite and sounding rocket missions monitoring.

  2. From Science Reserves to Sustainable Multiple Uses beyond Earth orbit: Evaluating Issues on the Path towards Balanced Environmental Management on Planetary Bodies (United States)

    Race, Margaret

    Over the past five decades, our understanding of space beyond Earth orbit has been shaped by a succession of mainly robotic missions whose technologies have enabled scientists to answer diverse science questions about celestial bodies across the solar system. For all that time, exploration has been guided by planetary protection policies and principles promulgated by COSPAR and based on provisions in Article IX of the Outer Space Treaty of 1967. Over time, implementation of the various COSPAR planetary protection policies have sought to avoid harmful forward and backward contamination in order to ensure the integrity of science findings, guide activities on different celestial bodies, and appropriately protect Earth whenever extraterrestrial materials have been returned. The recent increased interest in extending both human missions and commercial activities beyond Earth orbit have prompted discussions in various quarters about the need for updating policies and guidelines to ensure responsible, balanced space exploration and use by all parties, regardless whether activities are undertaken by governmental or non-governmental entities. Already, numerous researchers and workgroups have suggested a range of different ways to manage activities on celestial environments (e.g, wilderness parks, exclusion zones, special regions, claims, national research bases, environmental impact assessments, etc.). While the suggestions are useful in thinking about how to manage future space activities, they are not based on any systematically applied or commonly accepted criteria (scientific or otherwise). In addition, they are borrowed from terrestrial approaches for environmental protection, which may or may not have direct applications to space environments. As noted in a recent COSPAR-PEX workshop (GWU 2012), there are no clear definitions of issues such as harmful contamination, the environment to be protected, or what are considered reasonable activity or impacts for particular

  3. The Mission Accessible Near-Earth Object Survey (MANOS): Project Status (United States)

    Moskovitz, Nicholas; Thirouin, Audrey; Mommert, Michael; Thomas, Cristina A.; Skiff, Brian; Polishook, David; Burt, Brian; Trilling, David E.; DeMeo, Francesca E.; Binzel, Richard P.; Christensen, Eric J.; Willman, Mark; Hinkle, Mary


    The Mission Accessible Near-Earth Object Survey (MANOS) is a physical characterization survey of sub-km, low delta-v, newly discovered near-Earth objects (NEOs). MANOS aims to collect astrometry, lightcurve photometry, and reflectance spectra for a representative sample of these important target of opportunity objects in a rarely observed size range. We employ a diverse set of large aperture (2-8 meter) telescopes and observing modes (queue, remote, classical) to overcome the challenge of observing faint NEOs moving at high non-sidereal rates with short observing windows. We target approximately 10% of newly discovered NEOs every month for follow-up characterization.The first generation MANOS ran from late 2013 to early 2017, using telescopes at Lowell Observatory, NOAO, and the University of Hawaii. This resulted in the collection of data for over 500 targets. These data are continuing to provide new insights into the NEO population as a whole as well as for individual objects of interest. Science highlights include identification of the four fastest rotating minor planets found to date with rotation periods under 20 seconds, constraints on the distribution of NEO morphologies as quantified by de-biased estimates for lightcurve-derived axis ratios, and the compositional distribution of NEOs at sizes under 100 meters.The second generation MANOS will begin in late 2017 and will employ much of the same strategies while continuing to build a comprehensive dataset of NEO physical properties. This will grow the MANOS sample to ~1000 objects and provide the means to better address key questions related to understanding the physical properties of NEOs, their viability as exploration mission targets, and their relationship to Main Belt asteroids and meteorites. This continuation of MANOS will include an increased focus on spectroscopic observations at near-IR wavelengths using a new instrument called NIHTS (the Near-Infrared High-Throughput Spectrograph) at Lowell

  4. Détermination d’une orbite autour de L2 pour la mission CHEOPS


    Simeoni, Matthieu Martin Jean-Andre; Scheinmann, Nathan


    Afin de déterminer l’orbite qu’un satellite d’observation d’exoplanètes devait adopter, il a été nécessaire de considérer les points de Lagrange et plus particulièrement le deuxième de ces points. Dans les pages suivantes, nous localisons les trois premiers de ces points (L1, L2 et L3), expliquons en quoi ils sont importants et démontrons la quasi-stabilité de L1 et L2. Ensuite, nous analysons les différents types d’orbites quasi-périodiques qui existent autour de L2 et construisons une orbit...

  5. 78 FR 14920 - Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service Geostationary-Orbit... (United States)


    ... COMMISSION 47 CFR Parts 2 and 25 Earth Stations Aboard Aircraft Communicating With Fixed-Satellite Service... technical and licensing rules for Earth Stations Aboard Aircraft (ESAA), i.e., earth stations on aircraft...-11.2 GHz, 11.45-11.7 GHz, 11.7-12.2 GHz (space-to-Earth or downlink) and 14.0-14.5 GHz (Earth-to...

  6. Optimal Finite-Thrust Trans-earth Injection (TEI) Maneuvers for a Low Lunar Orbit (LLO) Earth Return Mission (United States)


    0.1 0.12 0.14 0.16 Time (hrs) F & d 4 S /d t4 (s ca le d) Thrust (F) d4S/ dt4 Figure 60. Fourth Time Derivative of Switching Function for...F) d4S/ dt4 Figure 61. Fourth Time Derivative of Switching Function for 2-Point Guess Solution 89 0.1 0.2 0.3 0.4 1.7 1.8 1.9 2 2.1x 10 -7 Time

  7. A Novel Double Cluster and Principal Component Analysis-Based Optimization Method for the Orbit Design of Earth Observation Satellites

    Directory of Open Access Journals (Sweden)

    Yunfeng Dong


    Full Text Available The weighted sum and genetic algorithm-based hybrid method (WSGA-based HM, which has been applied to multiobjective orbit optimizations, is negatively influenced by human factors through the artificial choice of the weight coefficients in weighted sum method and the slow convergence of GA. To address these two problems, a cluster and principal component analysis-based optimization method (CPC-based OM is proposed, in which many candidate orbits are gradually randomly generated until the optimal orbit is obtained using a data mining method, that is, cluster analysis based on principal components. Then, the second cluster analysis of the orbital elements is introduced into CPC-based OM to improve the convergence, developing a novel double cluster and principal component analysis-based optimization method (DCPC-based OM. In DCPC-based OM, the cluster analysis based on principal components has the advantage of reducing the human influences, and the cluster analysis based on six orbital elements can reduce the search space to effectively accelerate convergence. The test results from a multiobjective numerical benchmark function and the orbit design results of an Earth observation satellite show that DCPC-based OM converges more efficiently than WSGA-based HM. And DCPC-based OM, to some degree, reduces the influence of human factors presented in WSGA-based HM.

  8. Radiation Protection Effectiveness of Polymeric Based Shielding Materials at Low Earth Orbit (United States)

    Badavi, Francis F.; Stewart-Sloan, Charlotte R.; Wilson, John W.; Adams, Daniel O.


    Correlations of limited ionizing radiation measurements onboard the Space Transportation System (STS; shuttle) and the International Space Station (ISS) with numerical simulations of charged particle transport through spacecraft structure have indicated that usage of hydrogen rich polymeric materials improves the radiation shielding performance of space structures as compared to the traditionally used aluminum alloys. We discuss herein the radiation shielding correlations between measurements on board STS-81 (Atlantis, 1997) using four polyethylene (PE) spheres of varying radii, and STS-89 (Endeavour, 1998) using aluminum alloy spheres; with numerical simulations of charged particle transport using the Langley Research Center (LaRC)-developed High charge (Z) and Energy TRaNsport (HZETRN) algorithm. In the simulations, the Galactic Cosmic Ray (GCR) component of the ionizing radiation environment at Low Earth Orbit (LEO) covering ions in the 1< or equals Z< or equals 28 range is represented by O'Neill's (2004) model. To compute the transmission coefficient for GCR ions at LEO, O'Neill's model is coupled with the angular dependent LaRC cutoff model. The trapped protons/electrons component of LEO environment is represented by a LaRC-developed time dependent procedure which couples the AP8min/AP8max, Deep River Neutron Monitor (DRNM) and F10.7 solar radio frequency measurements. The albedo neutron environment resulting from interaction of GCR ions with upper atmosphere is modeled through extrapolation of the Atmospheric Ionizing Radiation (AIR) measurements. With the validity of numerical simulations through correlation with PE and aluminum spheres measurements established, we further present results from the expansion of the simulations through the selection of high hydrogen content commercially available polymeric constituents such as PE foam core and Spectra fiber(Registered TradeMark) composite face sheet to assess their radiation shield properties as compared to

  9. May 2005 Halo CMEs and Galactic Cosmic Ray Flux Changes at Earth's Orbit (United States)

    Ahluwalia, H. S.; Alania, M. V.; Wawrzynczak, A.; Ygbuhay, R. C.; Fikani, M. M.


    The pressure corrected hourly data from the global network of cosmic ray detectors, measurements of the interplanetary magnetic field (IMF) intensity ( B) at Earth's orbit and its components B x , B y , B z (in the geocentric solar ecliptic coordinates) are used to conduct a comprehensive study of the galactic cosmic ray (GCR) intensity fluctuations caused by the halo coronal mass ejection of 13 May 2005. Distinct differences exist in GCR timelines recorded by neutron monitors (NMs) and multidirectional muon telescopes (MTs), the latter respond to the high rigidity portion of the GCR differential rigidity spectrum. The Forbush decrease (FD) onset in MTs is delayed (˜5 h) with respect to the onset of a geomagnetic storm sudden commencement (SSC) and a large pre-increase is present in MT data before, during, and after the SSC onset, of unknown origin. The rigidity spectrum, for a range of GCR rigidities (≤200 GV), is a power law in rigidity (R) with a negative exponent ( γ=-1.05) at GCR minimum intensity, leading us to infer that the quasi-linear theory of modulation is inconsistent with observations at high rigidities (>1 GV); the results support the force field theory of modulation. At present, we do not have a comprehensive model for the FD explaining quantitatively all the observational features but we present a preliminary model listing physical processes that may contribute to a FD timeline. We explored the connections between different phases of the FD and the power spectra of IMF components but did not find a sustained relationship.

  10. Organ shielding and doses in Low-Earth orbit calculated for spherical and anthropomorphic phantoms (United States)

    Matthiä, Daniel; Berger, Thomas; Reitz, Günther


    Humans in space are exposed to elevated levels of radiation compared to ground. Different sources contribute to the total exposure with galactic cosmic rays being the most important component. The application of numerical and anthropomorphic phantoms in simulations allows the estimation of dose rates from galactic cosmic rays in individual organs and whole body quantities such as the effective dose. The male and female reference phantoms defined by the International Commission on Radiological Protection and the hermaphrodite numerical RANDO phantom are voxel implementations of anthropomorphic phantoms and contain all organs relevant for radiation risk assessment. These anthropomorphic phantoms together with a spherical water phantom were used in this work to translate the mean shielding of organs in the different anthropomorphic voxel phantoms into positions in the spherical phantom. This relation allows using a water sphere as surrogate for the anthropomorphic phantoms in both simulations and measurements. Moreover, using spherical phantoms in the calculation of radiation exposure offers great advantages over anthropomorphic phantoms in terms of computational time. In this work, the mean shielding of organs in the different voxel phantoms exposed to isotropic irradiation is presented as well as the corresponding depth in a water sphere. Dose rates for Low-Earth orbit from galactic cosmic rays during solar minimum conditions were calculated using the different phantoms and are compared to the results for a spherical water phantom in combination with the mean organ shielding. For the spherical water phantom the impact of different aluminium shielding between 1 g/cm2 and 100 g/cm2 was calculated. The dose equivalent rates were used to estimate the effective dose rate.

  11. Cosmic radiation monitoring at low-Earth orbit by means of thermoluminescence and plastic nuclear track detectors

    Czech Academy of Sciences Publication Activity Database

    Ambrožová, Iva; Pachnerová Brabcová, Kateřina; Kubančák, Ján; Šlegl, Jakub; Tolochek, R. V.; Ivanova, O. A.; Shurshakov, V. A.


    Roč. 106, č. 12 (2017), s. 262-266 ISSN 1350-4487 R&D Projects: GA ČR GJ15-16622Y Institutional support: RVO:61389005 Keywords : BION-M1 * cosmic radiation * low earth orbit * passive detector * thermoluminescent detector * plastic nuclear track detector Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.442, year: 2016

  12. Guidance Algorithms for Non-Drifting Trajectory Generation and Control in RendezVous Missions into Elliptical Orbits (United States)

    DiSotto, Emanuele; Bastante, Juan Carlos; Drai, Remi


    Safety requirement represents one of the most critical aspect when defining the operational profile for a RendezVous mission. This requirement specially affects the design of the guidance algorithms that need to be tailored to guarantee what is normally referred to as Passive Trajectory Protection . The basic idea of passive trajectory protection is to design all the trajectory elements in an approach sequence such that if, at any point of the trajectory, thrust control ceases, the resulting free drift motion will remain collision free during a certain amount of time. This paper deals with the design and performances assessment of specific guidance algorithm addressing this issue. Firstly the problem is addressed for circular orbit using the Traveling Ellipse formulation for the relative motion. Secondly a solution for the RendezVous into a generic elliptical orbit is presented. This is based on a reduced transition matrix obtained through a description of the relative motion based on the first order variation of the orbital elements.

  13. Neutron Measurements for Radiation Protection in Low Earth Orbit - History and Future (United States)

    Golightly, M. J.; Se,pmes. E/


    The neutron environment inside spacecraft has been of interest from a scientific and radiation protection perspective since early in the history of manned spaceflight. With 1:.1e exception of a few missions which carried plutonium-fueled radioisotope thermoelectric generators, all of the neutrons inside the spacecraft are secondary radiations resulting from interactions of high-energy charged particles with nuclei in the Earth's atmosphere, spacecraft structural materials, and the astronaut's own bodies. Although of great interest, definitive measurements of the spacecraft neutron field have been difficult due to the wide particle energy range and the limited available volume and power for traditional techniques involving Bonner spheres. A multitude of measurements, however, have been made of the neutron environment inside spacecraft. The majority of measurements were made using passive techniques including metal activation fo ils, fission foils, nuclear photoemulsions, plastic track detectors, and thermoluminescent detectors. Active measurements have utilized proton recoil spectrometers (stilbene), Bonner Spheres eRe proportional counter based), and LiI(Eu)phoswich scintillation detectors. For the International Space Station (ISS), only the plastic track! thermoluminescent detectors are used with any regularity. A monitoring program utilizing a set of active Bonner spheres was carried out in the ISS Lab module from March - December 200l. These measurements provide a very limited look at the crew neutron exposure, both in time coverage and neutron energy coverage. A review of the currently published data from past flights will be made and compared with the more recent results from the ISS. Future measurement efforts using currently available techniques and those in development will be also discussed.

  14. IPv6 and IPsec Tests of a Space-Based Asset, the Cisco Router in Low Earth Orbit (CLEO) (United States)

    Ivancic, William; Stewart, David; Wood, Lloyd; Jackson, Chris; Northam, James; Wilhelm, James


    This report documents the design of network infrastructure to support testing and demonstrating network-centric operations and command and control of space-based assets, using IPv6 and IPsec. These tests were performed using the Cisco router in Low Earth Orbit (CLEO), an experimental payload onboard the United Kingdom--Disaster Monitoring Constellation (UK-DMC) satellite built and operated by Surrey Satellite Technology Ltd (SSTL). On Thursday, 29 March 2007, NASA Glenn Research Center, Cisco Systems and SSTL performed the first configuration and demonstration of IPsec and IPv6 onboard a satellite in low Earth orbit. IPv6 is the next generation of the Internet Protocol (IP), designed to improve on the popular IPv4 that built the Internet, while IPsec is the protocol used to secure communication across IP networks. This demonstration was made possible in part by NASA s Earth Science Technology Office (ESTO) and shows that new commercial technologies such as mobile networking, IPv6 and IPsec can be used for commercial, military and government space applications. This has direct application to NASA s Vision for Space Exploration. The success of CLEO has paved the way for new spacebased Internet technologies, such as the planned Internet Routing In Space (IRIS) payload at geostationary orbit, which will be a U.S. Department of Defense Joint Capability Technology Demonstration. This is a sanitized report for public distribution. All real addressing has been changed to psueco addressing.

  15. A systematic method of generating Galilean satellite-to-satellite transfers for Orbiter/Lander missions (United States)

    Soldner, J. K.; Feingold, H.


    A Galilean satellite tour design strategy is presented which minimizes the approach velocities at the target satellites. A technique is developed such that once a Hohmann transfer is established between any two adjacent Galilean satellites, transfer trajectories to the remaining Galilean satellites can be derived in a systematic manner. A relationship between spacecraft orbital period and perijove radius is used to develop an algorithm which produces transfer trajectories by simply accounting for the satellites' angular position. The algorithm is incorporated into a FORTRAN code which demonstrates that a finite number of realizable trajectories exist in the specialized Galilean satellite tours due to resonance phasing. The basic assumption is made that the orbits of all the Galilean satellites are circular and coplanar.

  16. NASA Space Missions to Asteroids: Protecting the Earth from NEO Impacts (United States)

    Morrison, David; Berry, William E. (Technical Monitor)


    There is now a general recognition of the hazard of impacts on Earth by comets and asteroids, but there is yet no consensus concerning international actions that should be taken to protect the planet from such impacts. An essential step in the analysis of the situation involves estimating the relative hazard posed by comets and asteroids of different sizes and orbits. All recent studies agree that the larger impacts pose the greater danger, and that our primary concern from the perspective of total risk should be on impacts that are large enough to cause global ecological catastrophe. These global catastrophes are also of special interest, since they (alone among natural disasters) have the potential to destroy civilization. Studies of the sensitivity of the Earth's environment suggest that the energy threshold energy for causing a global catastrophe is at about 1 million megatons, corresponding to impactor diameters of 1.5 to 2 km. This information leads naturally to a strategy of concentrating on the larger NEOs, say those 1 km or more in diameter. This is the rationale for the Spaceguard Survey, which must be the highest priority in mitigation efforts. The second question concerns the value of developing standing defensive systems that could deflect or destroy an incoming NEO. In the case of the asteroids larger than 1 km in diameter, no such system is needed, since there will be ample time (at least several decades) between the discovery of the threatening object by Spaceguard and the requirement to take action against it. In the case of objects smaller than 1 km diameter, development of defensive systems is not cost-effective; there are many greater dangers to persons and property that are much more urgent. Only in the case of large long-period comets is there a rationale for standing defense systems. The question is also raised whether the risks inherent in developing and maintaining a defense system might be greater than the impact risks it is intended to

  17. High-Performance Data Analysis Tools for Sun-Earth Connection Missions (United States)

    Messmer, Peter


    The data analysis tool of choice for many Sun-Earth Connection missions is the Interactive Data Language (IDL) by ITT VIS. The increasing amount of data produced by these missions and the increasing complexity of image processing algorithms requires access to higher computing power. Parallel computing is a cost-effective way to increase the speed of computation, but algorithms oftentimes have to be modified to take advantage of parallel systems. Enhancing IDL to work on clusters gives scientists access to increased performance in a familiar programming environment. The goal of this project was to enable IDL applications to benefit from both computing clusters as well as graphics processing units (GPUs) for accelerating data analysis tasks. The tool suite developed in this project enables scientists now to solve demanding data analysis problems in IDL that previously required specialized software, and it allows them to be solved orders of magnitude faster than on conventional PCs. The tool suite consists of three components: (1) TaskDL, a software tool that simplifies the creation and management of task farms, collections of tasks that can be processed independently and require only small amounts of data communication; (2) mpiDL, a tool that allows IDL developers to use the Message Passing Interface (MPI) inside IDL for problems that require large amounts of data to be exchanged among multiple processors; and (3) GPULib, a tool that simplifies the use of GPUs as mathematical coprocessors from within IDL. mpiDL is unique in its support for the full MPI standard and its support of a broad range of MPI implementations. GPULib is unique in enabling users to take advantage of an inexpensive piece of hardware, possibly already installed in their computer, and achieve orders of magnitude faster execution time for numerically complex algorithms. TaskDL enables the simple setup and management of task farms on compute clusters. The products developed in this project have the

  18. 78 FR 14952 - Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service Geostationary-Orbit... (United States)


    ... COMMISSION 47 CFR Part 2 Earth Stations Aboard Aircraft Communicating with Fixed-Satellite Service... of Earth Stations Aboard Aircraft (ESAA) in the 14.0-14.5 GHz band from secondary to primary and... stations of the FSS on a primary basis in the 11.7-12.2 GHz band (space-to-Earth), on an unprotected basis...

  19. Solid Earth: Introduction (United States)

    Rummel, R.


    The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.

  20. Group dynamics in a long-term blind endeavor on Earth: An analog for space missions (Lewis & Clark Expedition group dynamic analysis) (United States)

    Allner, M.; Rygalov, V.


    In 1803, President Thomas Jefferson set fourth a military expedition led by Captains M. Lewis and W. Clark (Lewis and Clark Expedition) on an exploration that would become an everlasting part of US national history and pride. Looking back at the events of this exploration, there are many similarities to the experiences future human space explorers will face as we look to colonize the Moon and travel to Mars and beyond (NASA Vision for Space Exploration, 2004): The Lewis and Clark Expedition lasted almost three years and involved a crew of 43 men traveling up the Missouri River to explore the unknown lands and a possible water route to the Pacific Ocean; The Expedition took place far away from customary comfortable environments known to European settlers in the early 18th century; The Expedition involved a remotely confined high-perceived risk environment with high levels of uncertainty providing stresses and every day challenges for the crew; Supplies brought on the mission were limited (mainly a mass/weight issue rather than cost), therefore the discovery and use of environmental resources (In-Situ Resource Utilization approach, including info-resources to mitigate uncertainty) was necessary for crew survival. The environments astronauts will encounter in space and on the Moon and Mars due to high risk and uncertainty will be in many aspects similar to what Lewis and Clark's crew experienced, as environments will be hostile and unforgiving if problems arise and aren't resolved quickly. The analysis provided in this research paper is relevant because the Lewis and Clark Expedition needed to move extensively and with minimal supplies. Polar remote settings, which were analyzed extensively, were different from this expedition due to the fact that these missions did not encompass extensive movement of crew facilities and supplies and were more like space missions orbiting the Earth. Using past space station results of performance on orbit in correlation with a

  1. The First Neptune Analog or Super-Earth with a Neptune-Like Orbit: MOA-2013-BLG-605Lb (United States)

    Sumi, T.; Bennett, D. P.; Udalski, A.; Gould, A.; Poleski, R.; Bond, I. A.; Skowron, J.; Rattenbury, N.; Pogge, R. W.; Bensby, T.


    We present the discovery of the first Neptune analog exoplanet or super-Earth with a Neptune-like orbit, MOA- 2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at 9 approximately 14 times the expected position of the snow line, a(sub snow), which is similar to Neptune's separation of 11 a(sub snow) from the Sun. The planet/host-star mass ratio is q = (3.6 +/- 0.7) × 10(exp -4) and the projected separation normalized by the Einstein radius is s = 2.39 +/- 0.05. There are three degenerate physical solutions and two of these are due to a new type of degeneracy in the microlensing parallax parameters, which we designate "the wide degeneracy." The three models have (i) a Neptune-mass planet with a mass of M(sub p) = 21(+6/-7)(M) orbiting a low-mass M-dwarf with a mass of M(sub h) = 0.19(+0.05/-0.06 (solar mass)), (ii) a mini-Neptune with M(sub p) = 7.9(+1.8/-1.5)(M)) orbiting a brown dwarf host with M(sub h) = 0.068(+0.019/-0.011(solar mass)), and (iii) a super-Earth with M(sub p) = 3.2(+0.5/-0.3(M)) orbiting a low-mass brown dwarf host with M(sub h) = 0.025(+0.005/-0.004)(solar mass)), which is slightly favored. The 3D planet-host separations are 4.6(+4.7/-1.2)au, 2.1(+1.0/-0.2)au, and 0.94(+0.67/-0.02)au, which are 8.9(+10.5/-1.4)m 12(+7/-1), or 14(+11/-1) times larger than a(sub snow) for these models, respectively. Keck adaptive optics observations confirm that the lens is faint. This discovery suggests that low-mass planets with Neptune-like orbits are common. Therefore processes similar to the one that formed Neptune in our own solar system or cold super-Earths may be common in other solar systems.

  2. Human Missions to Near-Earth Asteroids: An Update on NASA's Current Status and Proposed Activities for Small Body Exploration (United States)

    Abell, P. A.; Mazanek, D. D.; Barbee, B. W.; Mink, R. G.; Landis, R. R.; Adamo, D. R.; Johnson, L. N.; Yeomans, D. K.; Reeves, D. M.; Larman, K. T.; hide


    Over the past several years, much attention has been focused on the human exploration of near-Earth asteroids (NEAs). Two independent NASA studies examined the feasibility of sending piloted missions to NEAs, and in 2009, the Augustine Commission identified NEAs as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. More recently the current U.S. presidential administration directed NASA to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010.

  3. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Directory of Open Access Journals (Sweden)

    S. Schweitzer


    Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We

  4. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites (United States)

    Schweitzer, S.; Kirchengast, G.; Proschek, V.


    LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that

  5. Low Earth orbit assessment of proton anisotropy using AP8 and AP9 trapped proton models. (United States)

    Badavi, Francis F; Walker, Steven A; Santos Koos, Lindsey M


    The completion of the International Space Station (ISS) in 2011 has provided the space research community with an ideal evaluation and testing facility for future long duration human activities in space. Ionized and secondary neutral particles radiation measurements inside ISS form the ideal tool for validation of radiation environmental models, nuclear reaction cross sections and transport codes. Studies using thermo-luminescent detectors (TLD), tissue equivalent proportional counter (TPEC), and computer aided design (CAD) models of early ISS configurations confirmed that, as input, computational dosimetry at low Earth orbit (LEO) requires an environmental model with directional (anisotropic) capability to properly describe the exposure of trapped protons within ISS. At LEO, ISS encounters exposure from trapped electrons, protons and geomagnetically attenuated galactic cosmic rays (GCR). For short duration studies at LEO, one can ignore trapped electrons and ever present GCR exposure contributions during quiet times. However, within the trapped proton field, a challenge arises from properly estimating the amount of proton exposure acquired. There exist a number of models to define the intensity of trapped particles. Among the established trapped models are the historic AE8/AP8, dating back to the 1980s and the recently released AE9/AP9/SPM. Since at LEO electrons have minimal exposure contribution to ISS, this work ignores the AE8 and AE9 components of the models and couples a measurement derived anisotropic trapped proton formalism to omnidirectional output from the AP8 and AP9 models, allowing the assessment of the differences between the two proton models. The assessment is done at a target point within the ISS-11A configuration (circa 2003) crew quarter (CQ) of Russian Zvezda service module (SM), during its ascending and descending nodes passes through the south Atlantic anomaly (SAA). The anisotropic formalism incorporates the contributions of proton narrow

  6. Orbital bistatic radar observations of asteroid Vesta by the Dawn mission. (United States)

    Palmer, Elizabeth M; Heggy, Essam; Kofman, Wlodek


    We present orbital bistatic radar observations of a small-body, acquired during occultation by the Dawn spacecraft at asteroid Vesta. The radar forward-scattering properties of different reflection sites are used to assess the textural properties of Vesta's surface at centimeter-to-decimeter scales and are compared to subsurface hydrogen concentrations observed by Dawn's Gamma Ray and Neutron Detector to assess potential volatile occurrence in the surface and shallow subsurface. We observe significant differences in surface radar reflectivity, implying substantial spatial variations in centimeter-to-decimeter-scale surface roughness. Our results suggest that unlike the Moon, Vesta's surface roughness variations cannot be explained by cratering processes only. In particular, the occurrence of heightened hydrogen concentrations within large smoother terrains (over hundreds of square kilometers) suggests that potential ground-ice presence may have contributed to the formation of Vesta's current surface texture. Our observations are consistent with geomorphological evidence of transient water flow from Dawn Framing Camera images.The Dawn spacecraft has provided orbital bistatic radar observations of a small body in the solar system. Here, the authors present results from Vesta suggesting that smooth terrains with heightened hydrogen concentrations indicate that ground-ice presence potentially helped shape Vesta's current surface texture.

  7. Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki (United States)

    Imamura, Takeshi; Ando, Hiroki; Tellmann, Silvia; Pätzold, Martin; Häusler, Bernd; Yamazaki, Atsushi; Sato, Takao M.; Noguchi, Katsuyuki; Futaana, Yoshifumi; Oschlisniok, Janusz; Limaye, Sanjay; Choudhary, R. K.; Murata, Yasuhiro; Takeuchi, Hiroshi; Hirose, Chikako; Ichikawa, Tsutomu; Toda, Tomoaki; Tomiki, Atsushi; Abe, Takumi; Yamamoto, Zen-ichi; Noda, Hirotomo; Iwata, Takahiro; Murakami, Shin-ya; Satoh, Takehiko; Fukuhara, Tetsuya; Ogohara, Kazunori; Sugiyama, Ko-ichiro; Kashimura, Hiroki; Ohtsuki, Shoko; Takagi, Seiko; Yamamoto, Yukio; Hirata, Naru; Hashimoto, George L.; Yamada, Manabu; Suzuki, Makoto; Ishii, Nobuaki; Hayashiyama, Tomoko; Lee, Yeon Joo; Nakamura, Masato


    After the arrival of Akatsuki spacecraft of Japan Aerospace Exploration Agency at Venus in December 2015, the radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles of the Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for the experiment. The quantities to be retrieved are the atmospheric pressure, the temperature, the sulfuric acid vapor mixing ratio, and the electron density. Temperature profiles were successfully obtained down to 38 km altitude and show distinct atmospheric structures depending on the altitude. The overall structure is close to the previous observations, suggesting a remarkable stability of the thermal structure. Local time-dependent features are seen within and above the clouds, which is located around 48-70 km altitude. The H2SO4 vapor density roughly follows the saturation curve at cloud heights, suggesting equilibrium with cloud particles. The ionospheric electron density profiles are also successfully retrieved, showing distinct local time dependence. Akatsuki RS mainly probes the low and middle latitude regions thanks to the near-equatorial orbit in contrast to the previous radio occultation experiments using polar orbiters. Studies based