(abstract) Spacecraft Doppler Tracking with the Deep Space Network in the Search for Gravitational Waves

Science.gov (United States)

Asmar, Sami; Renzetti, Nicholas

1994-01-01

The Deep Space Network generates accurate radio science data observables for investigators who use radio links between spacecraft and the Earth to examine small changes in the phase and/or amplitude of the signal to study a wide variety of structures and phenomena in space. Several such studies are directed at aspects of the theory of general relativity such as gravitational redshift and gravitational waves. A gravitational wave is a propagating, polarized gravitational field, a ripple in the curvature of space-time. In Einstein's theory of general relativity, the waves are propagating solutions of the Einstein field equations. Their amplitudes are dimensionless strain amplitudes that change the fractional difference in distance between test masses and the rates at which separated clocks keep time. Predicted by all relativistic theories of gravity, they are extremely weak (the ratio of gravitational forces to electrical forces is about 10(sup -40)) and are generated at detectable levels only by astrophysical sources - very massive sources under violent dynamical conditions. The waves have never been detected but searches in the low-frequency band using Doppler tracking of many spacecraft have been conducted and others are being planned. Upper limits have been placed on the gravitational wave strength with the best sensitivities to date are for periodic waves being 7 x 10(sup -15).

Dips spacecraft integration issues

International Nuclear Information System (INIS)

Determan, W.R.; Harty, R.B.

1988-01-01

The Department of Energy, in cooperation with the Department of Defense, has recently initiated the dynamic isotope power system (DIPS) demonstration program. DIPS is designed to provide 1 to 10 kW of electrical power for future military spacecraft. One of the near-term missions considered as a potential application for DIPS was the boost surveillance and tracking system (BSTS). A brief review and summary of the reasons behind a selection of DIPS for BSTS-type missions is presented. Many of these are directly related to spacecraft integration issues; these issues will be reviewed in the areas of system safety, operations, survivability, reliability, and autonomy

An Orbit Propagation Software for Mars Orbiting Spacecraft

Directory of Open Access Journals (Sweden)

Young-Joo Song

2004-12-01

Full Text Available An orbit propagation software for the Mars orbiting spacecraft has been developed and verified in preparations for the future Korean Mars missions. Dynamic model for Mars orbiting spacecraft has been studied, and Mars centered coordinate systems are utilized to express spacecraft state vectors. Coordinate corrections to the Mars centered coordinate system have been made to adjust the effects caused by Mars precession and nutation. After spacecraft enters Sphere of Influence (SOI of the Mars, the spacecraft experiences various perturbation effects as it approaches to Mars. Every possible perturbation effect is considered during integrations of spacecraft state vectors. The Mars50c gravity field model and the Mars-GRAM 2001 model are used to compute perturbation effects due to Mars gravity field and Mars atmospheric drag, respectively. To compute exact locations of other planets, JPL's DE405 ephemerides are used. Phobos and Deimos's ephemeris are computed using analytical method because their informations are not released with DE405. Mars Global Surveyor's mapping orbital data are used to verify the developed propagator performances. After one Martian day propagation (12 orbital periods, the results show about maximum ±5 meter errors, in every position state components(radial, cross-track and along-track, when compared to these from the Astrogator propagation in the Satellite Tool Kit. This result shows high reliability of the developed software which can be used to design near Mars missions for Korea, in future.

Feedback attitude sliding mode regulation control of spacecraft using arm motion

Science.gov (United States)

Shi, Ye; Liang, Bin; Xu, Dong; Wang, Xueqian; Xu, Wenfu

2013-09-01

The problem of spacecraft attitude regulation based on the reaction of arm motion has attracted extensive attentions from both engineering and academic fields. Most of the solutions of the manipulator’s motion tracking problem just achieve asymptotical stabilization performance, so that these controllers cannot realize precise attitude regulation because of the existence of non-holonomic constraints. Thus, sliding mode control algorithms are adopted to stabilize the tracking error with zero transient process. Due to the switching effects of the variable structure controller, once the tracking error reaches the designed hyper-plane, it will be restricted to this plane permanently even with the existence of external disturbances. Thus, precise attitude regulation can be achieved. Furthermore, taking the non-zero initial tracking errors and chattering phenomenon into consideration, saturation functions are used to replace sign functions to smooth the control torques. The relations between the upper bounds of tracking errors and the controller parameters are derived to reveal physical characteristic of the controller. Mathematical models of free-floating space manipulator are established and simulations are conducted in the end. The results show that the spacecraft’s attitude can be regulated to the position as desired by using the proposed algorithm, the steady state error is 0.000 2 rad. In addition, the joint tracking trajectory is smooth, the joint tracking errors converges to zero quickly with a satisfactory continuous joint control input. The proposed research provides a feasible solution for spacecraft attitude regulation by using arm motion, and improves the precision of the spacecraft attitude regulation.

Gravity and Macro-Model Tuning for the Geosat Follow-on Spacecraft

Science.gov (United States)

Lemoine, Frank G.; Rowlands, David D.; Marr, Gregory C.; Zelensky, Nikita P.; Luthcke, Scott B.; Cox, Christopher M.

1999-01-01

The US Navy's GEOSAT Follow-On (GFO) spacecraft was launched on February 10, 1998 and the primary objective of the mission was to map the oceans using a radar altimeter. The spacecraft tracking complement consisted of GPS receivers, a laser retroreflector and Doppler beacons. Since the GPS receivers have not yet returned reliable data, the only means of providing high-quality precise orbits has been though satellite laser ranging (SLR). The spacecraft has been tracked by the international satellite laser ranging network since April 22, 1998, and an average of 7.4 passes per day have been obtained from US and participating foreign stations. Since the predicted radial orbit error due to the gravity field is two to three cm, the largest contributor to the high SLR residuals (7-10 cm RMS for five day arcs) is the mismodelling of the non-conservative forces, not withstanding the development of a three-dimensional eight-panel model and an analytical attitude model for the GFO spacecraft. The SLR residuals show a clear correlation with beta-prime (solar elevation) angle, peaking in mid-August 1998 when the beta-prime angle reached -80 to -90 degrees. In this paper we discuss the tuning of the non-conservative force model, for GFO and report the subsequent addition of the GFO tracking data to the Earth gravity model solutions.

Noncoherent Doppler tracking: first flight results

Science.gov (United States)

DeBoy, Christopher C.; Robert Jensen, J.; Asher, Mark S.

2005-01-01

Noncoherent Doppler tracking has been devised as a means to achieve highly accurate, two-way Doppler measurements with a simple, transceiver-based communications system. This technique has been flown as an experiment on the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) spacecraft, (launched 7 December 2001), as the operational technique for Doppler tracking on CONTOUR, and is baselined on several future deep space missions at JHU/APL. This paper reports on initial results from a series of successful tests of this technique between the TIMED spacecraft and NASA ground stations in the Deep Space Network. It also examines the advantages that noncoherent Doppler tracking and a transceiver-based system may offer to small satellite systems, including reduced cost, mass, and power.

Ground Simulation of an Autonomous Satellite Rendezvous and Tracking System Using Dual Robotic Systems

Science.gov (United States)

Trube, Matthew J.; Hyslop, Andrew M.; Carignan, Craig R.; Easley, Joseph W.

2012-01-01

A hardware-in-the-loop ground system was developed for simulating a robotic servicer spacecraft tracking a target satellite at short range. A relative navigation sensor package "Argon" is mounted on the end-effector of a Fanuc 430 manipulator, which functions as the base platform of the robotic spacecraft servicer. Machine vision algorithms estimate the pose of the target spacecraft, mounted on a Rotopod R-2000 platform, relay the solution to a simulation of the servicer spacecraft running in "Freespace", which performs guidance, navigation and control functions, integrates dynamics, and issues motion commands to a Fanuc platform controller so that it tracks the simulated servicer spacecraft. Results will be reviewed for several satellite motion scenarios at different ranges. Key words: robotics, satellite, servicing, guidance, navigation, tracking, control, docking.

The spacecraft encounters of Comet Halley

Science.gov (United States)

Asoka Mendis, D.; Tsurutani, Bruce T.

1986-01-01

The characteristics of the Comet Halley spacecraft 'fleet' (VEGA 1 and VEGA 2, Giotto, Suisei, and Sakigake) are presented. The major aims of these missions were (1) to discover and characterize the nucleus, (2) to characterize the atmosphere and ionosphere, (3) to characterize the dust, and (4) to characterize the nature of the large-scale comet-solar wind interaction. While the VEGA and Giotto missions were designed to study all four areas, Suisei addressed the second and fourth. Sakigake was designed to study the solar wind conditions upstream of the comet. It is noted that NASA's Deep Space Network played an important role in spacecraft tracking.

Attitude Fusion Techniques for Spacecraft

DEFF Research Database (Denmark)

Bjarnø, Jonas Bækby

Spacecraft platform instability constitutes one of the most significant limiting factors in hyperacuity pointing and tracking applications, yet the demand for accurate, timely and reliable attitude information is ever increasing. The PhD research project described within this dissertation has...... served to investigate the solution space for augmenting the DTU μASC stellar reference sensor with a miniature Inertial Reference Unit (IRU), thereby obtaining improved bandwidth, accuracy and overall operational robustness of the fused instrument. Present day attitude determination requirements are met...... of the instrument, and affecting operations during agile and complex spacecraft attitude maneuvers. As such, there exists a theoretical foundation for augmenting the high frequency performance of the μASC instrument, by harnessing the complementary nature of optical stellar reference and inertial sensor technology...

Using neuromorphic optical sensors for spacecraft absolute and relative navigation

Science.gov (United States)

Shake, Christopher M.

We develop a novel attitude determination system (ADS) for use on nano spacecraft using neuromorphic optical sensors. The ADS intends to support nano-satellite operations by providing low-cost, low-mass, low-volume, low-power, and redundant attitude determination capabilities with quick and straightforward onboard programmability for real time spacecraft operations. The ADS is experimentally validated with commercial-off-the-shelf optical devices that perform sensing and image processing on the same circuit board and are biologically inspired by insects' vision systems, which measure optical flow while navigating in the environment. The firmware on the devices is modified to both perform the additional biologically inspired task of tracking objects and communicate with a PC/104 form-factor embedded computer running Real Time Application Interface Linux used on a spacecraft simulator. Algorithms are developed for operations using optical flow, point tracking, and hybrid modes with the sensors, and the performance of the system in all three modes is assessed using a spacecraft simulator in the Advanced Autonomous Multiple Spacecraft (ADAMUS) laboratory at Rensselaer. An existing relative state determination method is identified to be combined with the novel ADS to create a self-contained navigation system for nano spacecraft. The performance of the method is assessed in simulation and found not to match the results from its authors using only conditions and equations already published. An improved target inertia tensor method is proposed as an update to the existing relative state method, but found not to perform as expected, but is presented for others to build upon.

Schema for Spacecraft-Command Dictionary

Science.gov (United States)

Laubach, Sharon; Garcia, Celina; Maxwell, Scott; Wright, Jesse

2008-01-01

An Extensible Markup Language (XML) schema was developed as a means of defining and describing a structure for capturing spacecraft command- definition and tracking information in a single location in a form readable by both engineers and software used to generate software for flight and ground systems. A structure defined within this schema is then used as the basis for creating an XML file that contains command definitions.

26th Conference of Spacecraft TT&C Technology in China

CERN Document Server

Qian, Weiping

2013-01-01

Proceedings of the 26th Conference of Spacecraft TT&C Technology in China collects selected papers from the 26th Conference of Spacecraft TT&C Technology in China held in Nanjing on October 16-19, 2012. The book features state-of-the-art studies on spacecraft TT&C in China with the theme of “Shared and Flexible TT&C Systems”. The selected works can help  promote development of spacecraft TT&C technology towards interconnectivity, resource sharing, flexibility and high efficiency. Researchers and engineers in the field of aerospace engineering and communication engineering can benefit from the book. Rongjun Shen is the Academician of Chinese Academy of Engineering; Weiping Qian is the Director General of Beijing Institute of Tracking and Telecommunications Technology.

Superimposed disturbance in the ionosphere triggered by spacecraft launches in China

OpenAIRE

L. M. He; L. X. Wu; L. X. Wu; S. J. Liu; S. N. Liu

2015-01-01

Using GPS dual-frequency observations collected by continuously operating GPS tracking stations in China, superimposed disturbances caused by the integrated action of spacecraft's physical effect and chemical effect on ionosphere during the launches of the spacecrafts Tiangong-1 and Shenzhou-8 in China were firstly determined. The results show that the superimposed disturbance was composed of remarkable ionospheric waves and significant ionospheric depletion emerged after bo...

Experiments study on attitude coupling control method for flexible spacecraft

Science.gov (United States)

Wang, Jie; Li, Dongxu

2018-06-01

High pointing accuracy and stabilization are significant for spacecrafts to carry out Earth observing, laser communication and space exploration missions. However, when a spacecraft undergoes large angle maneuver, the excited elastic oscillation of flexible appendages, for instance, solar wing and onboard antenna, would downgrade the performance of the spacecraft platform. This paper proposes a coupling control method, which synthesizes the adaptive sliding mode controller and the positive position feedback (PPF) controller, to control the attitude and suppress the elastic vibration simultaneously. Because of its prominent performance for attitude tracking and stabilization, the proposed method is capable of slewing the flexible spacecraft with a large angle. Also, the method is robust to parametric uncertainties of the spacecraft model. Numerical simulations are carried out with a hub-plate system which undergoes a single-axis attitude maneuver. An attitude control testbed for the flexible spacecraft is established and experiments are conducted to validate the coupling control method. Both numerical and experimental results demonstrate that the method discussed above can effectively decrease the stabilization time and improve the attitude accuracy of the flexible spacecraft.

Spacecraft Tests of General Relativity

Science.gov (United States)

Anderson, John D.

1997-01-01

Current spacecraft tests of general relativity depend on coherent radio tracking referred to atomic frequency standards at the ground stations. This paper addresses the possibility of improved tests using essentially the current system, but with the added possibility of a space-borne atomic clock. Outside of the obvious measurement of the gravitational frequency shift of the spacecraft clock, a successor to the suborbital flight of a Scout D rocket in 1976 (GP-A Project), other metric tests would benefit most directly by a possible improved sensitivity for the reduced coherent data. For purposes of illustration, two possible missions are discussed. The first is a highly eccentric Earth orbiter, and the second a solar-conjunction experiment to measure the Shapiro time delay using coherent Doppler data instead of the conventional ranging modulation.

Spacecraft 3D Augmented Reality Mobile App

Science.gov (United States)

Hussey, Kevin J.; Doronila, Paul R.; Kumanchik, Brian E.; Chan, Evan G.; Ellison, Douglas J.; Boeck, Andrea; Moore, Justin M.

2013-01-01

The Spacecraft 3D application allows users to learn about and interact with iconic NASA missions in a new and immersive way using common mobile devices. Using Augmented Reality (AR) techniques to project 3D renditions of the mission spacecraft into real-world surroundings, users can interact with and learn about Curiosity, GRAIL, Cassini, and Voyager. Additional updates on future missions, animations, and information will be ongoing. Using a printed AR Target and camera on a mobile device, users can get up close with these robotic explorers, see how some move, and learn about these engineering feats, which are used to expand knowledge and understanding about space. The software receives input from the mobile device's camera to recognize the presence of an AR marker in the camera's field of view. It then displays a 3D rendition of the selected spacecraft in the user's physical surroundings, on the mobile device's screen, while it tracks the device's movement in relation to the physical position of the spacecraft's 3D image on the AR marker.

Innovative Technique for Noise Reduction in Spacecraft Doppler Tracking for Planetary Interior Studies

Science.gov (United States)

Notaro, V.; Armstrong, J. W.; Asmar, S.; Di Ruscio, A.; Iess, L.; Mariani, M., Jr.

2017-12-01

Precise measurements of spacecraft range rate, enabled by two-way microwave links, are used in radio science experiments for planetary geodesy including the determination of planetary gravitational fields for the purpose of modeling the interior structure. The final accuracies in the estimated gravity harmonic coefficients depend almost linearly on the Doppler noise in the link. We ran simulations to evaluate the accuracy improvement attainable in the estimation of the gravity harmonic coefficients of Venus (with a representative orbiter) and Mercury (with the BepiColombo spacecraft), using our proposed innovative noise-cancellation technique. We showed how the use of an additional, smaller and stiffer, receiving-only antenna could reduce the leading noise sources in a Ka-band two-way link such as tropospheric and antenna mechanical noises. This is achieved through a suitable linear combination (LC) of Doppler observables collected at the two antennas at different times. In our simulations, we considered a two-way link either from NASA's DSS 25 antenna in California or from ESA's DSA-3 antenna in Malargüe (Argentina). Moreover, we selected the 12-m Atacama Pathfinder EXperiment (APEX) in Chile as the three-way antenna and developed its tropospheric noise model using available atmospheric data and mechanical stability specifications. For an 8-hour Venus orbiter tracking pass in Chajnantor's winter/night conditions, the accuracy of the simulated LC Doppler observable at 10-s integration time is 6 mm/s, to be compared to 23 mm/s for the two-way link. For BepiColombo, we obtained 16.5 mm/s and 35 mm/s, respectively for the LC and two-way links. The benefits are even larger at longer time scales. Numerical simulations indicate that such noise reduction would provide significant improvements in the determination of Venus's and Mercury's gravity field coefficients. If implemented, this noise-reducing technique will be valuable for planetary geodesy missions, where the

Special Semaphore Scheme for UHF Spacecraft Communications

Science.gov (United States)

Butman, Stanley; Satorius, Edgar; Ilott, Peter

2006-01-01

A semaphore scheme has been devised to satisfy a requirement to enable ultrahigh- frequency (UHF) radio communication between a spacecraft descending from orbit to a landing on Mars and a spacecraft, in orbit about Mars, that relays communications between Earth and the lander spacecraft. There are also two subsidiary requirements: (1) to use UHF transceivers, built and qualified for operation aboard the spacecraft that operate with residual-carrier binary phase-shift-keying (BPSK) modulation at a selectable data rate of 8, 32, 128, or 256 kb/s; and (2) to enable low-rate signaling even when received signals become so weak as to prevent communication at the minimum BPSK rate of 8 kHz. The scheme involves exploitation of Manchester encoding, which is used in conjunction with residual-carrier modulation to aid the carrier-tracking loop. By choosing various sequences of 1s, 0s, or 1s alternating with 0s to be fed to the residual-carrier modulator, one would cause the modulator to generate sidebands at a fundamental frequency of 4 or 8 kHz and harmonics thereof. These sidebands would constitute the desired semaphores. In reception, the semaphores would be detected by a software demodulator.

Orbit Determination of Spacecraft in Earth-Moon L1 and L2 Libration Point Orbits

Science.gov (United States)

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

2011-01-01

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

Spacecraft TT&C and information transmission theory and technologies

CERN Document Server

Liu, Jiaxing

2015-01-01

Spacecraft TT&C and Information Transmission Theory and Technologies introduces the basic theory of spacecraft TT&C (telemetry, track and command) and information transmission. Combining TT&C and information transmission, the book presents several technologies for continuous wave radar including measurements for range, range rate and angle, analog and digital information transmissions, telecommand, telemetry, remote sensing and spread spectrum TT&C. For special problems occurred in the channels for TT&C and information transmission, the book represents radio propagation features and its impact on orbit measurement accuracy, and the effects caused by rain attenuation, atmospheric attenuation and multi-path effect, and polarization composition technology. This book can benefit researchers and engineers in the field of spacecraft TT&C and communication systems. Liu Jiaxing is a professor at The 10th Institute of China Electronics Technology Group Corporation.

Standardization and Economics of Nuclear Spacecraft, Final Report, Phase I, Sense Study

Energy Technology Data Exchange (ETDEWEB)

1973-03-01

Feasibility and cost benefits of nuclear-powered standardized spacecraft are investigated. The study indicates that two shuttle-launched nuclear-powered spacecraft should be able to serve the majority of unmanned NASA missions anticipated for the 1980's. The standard spacecraft include structure, thermal control, power, attitude control, some propulsion capability and tracking, telemetry, and command subsystems. One spacecraft design, powered by the radioisotope thermoelectric generator, can serve missions requiring up to 450 watts. The other spacecraft design, powered by similar nuclear heat sources in a Brayton-cycle generator, can serve missions requiring up to 21000 watts. Design concepts and trade-offs are discussed. The conceptual designs selected are presented and successfully tested against a variety of missions. The thermal design is such that both spacecraft are capable of operating in any earth orbit and any orientation without modification. Three-axis stabilization is included. Several spacecraft can be stacked in the shuttle payload compartment for multi-mission launches. A reactor-powered thermoelectric generator system, operating at an electric power level of 5000 watts, is briefly studied for applicability to two test missions of divers requirements. A cost analysis indicates that use of the two standardized spacecraft offers sizable savings in comparison with specially designed solar-powered spacecraft. There is a duplicate copy.

Gravitational-wave bursts from the nuclei of distant galaxies and quasars: proposal for detection using Doppler tracking of interplanetary spacecraft

International Nuclear Information System (INIS)

Thorne, K.S.; Braginsky, V.B.

1976-01-01

It is likely that supermassive black holes (Mapprox. =10 6 to 10 10 M/sub sun/) exist in the nuclei of many quasars and galaxies. The collapse which forms these holes and subsequent collisions between them should produce strong, broad-band bursts of gravitational waves: for a source of mass M at the Hubble distance of approx.10 10 light-years, the dimensionless amplitude would be h approx. 2 x 10 -17 x (M/10 6 M/sub sun/), and the duration of the burst would be tauapprox. (90 s) x (M/10 6 M/sub sun/). Such bursts might arrive at Earth as often as 50 times per year: or as rarely as once each 300 years. The detection of such bursts may be possible within the next few years using dual-frequency Doppler tracking of interplanetary spacecraft

Use of Faraday-rotation data from beacon satellites to determine ionospheric corrections for interplanetary spacecraft navigation

Science.gov (United States)

Royden, H. N.; Green, D. W.; Walson, G. R.

1981-01-01

Faraday-rotation data from the linearly polarized 137-MHz beacons of the ATS-1, SIRIO, and Kiku-2 geosynchronous satellites are used to determine the ionospheric corrections to the range and Doppler data for interplanetary spacecraft navigation. The JPL operates the Deep Space Network of tracking stations for NASA; these stations monitor Faraday rotation with dual orthogonal, linearly polarized antennas, Teledyne polarization tracking receivers, analog-to-digital converter/scanners, and other support equipment. Computer software examines the Faraday data, resolves the pi ambiguities, constructs a continuous Faraday-rotation profile and converts the profile to columnar zenith total electron content at the ionospheric reference point; a second program computes the line-of-sight ionospheric correction for each pass of the spacecraft over each tracking complex. Line-of-sight ionospheric electron content using mapped Faraday-rotation data is compared with that using dispersive Doppler data from the Voyager spacecraft; a difference of about 0.4 meters, or 5 x 10 to the 16th electrons/sq m is obtained. The technique of determining the electron content of interplanetary plasma by subtraction of the ionospheric contribution is demonstrated on the plasma torus surrounding the orbit of Io.

Effect of External Disturbing Gravity Field on Spacecraft Guidance and Surveying Line Layout for Marine Gravity Survey

Directory of Open Access Journals (Sweden)

HUANG Motao

2016-11-01

Full Text Available Centred on the support requirement of flying track control for a long range spacecraft, a detail research is made on the computation of external disturbing gravity field, the survey accuracy of gravity anomaly on the earth' surface and the program of surveying line layout for marine gravity survey. Firstly, the solution expression of navigation error for a long range spacecraft is analyzed and modified, and the influence of the earth's gravity field on flying track of spacecraft is evaluated. Then with a given limited quota of biased error of spacecraft drop point, the accuracy requirement for calculating the external disturbing gravity field is discussed and researched. Secondly, the data truncation error and the propagated data error are studied and estimated, and the quotas of survey resolution and computation accuracy for gravity anomaly on the earth' surface are determined. Finally, based on the above quotas, a corresponding program of surveying line layout for marine gravity survey is proposed. A numerical test has been made to prove the reasonableness and validity of the suggested program.

Singular formalism and admissible control of spacecraft with rotating flexible solar array

Directory of Open Access Journals (Sweden)

Lu Dongning

2014-02-01

Full Text Available This paper is concerned with the attitude control of a three-axis-stabilized spacecraft which consists of a central rigid body and a flexible sun-tracking solar array driven by a solar array drive assembly. Based on the linearization of the dynamics of the spacecraft and the modal identities about the flexible and rigid coupling matrices, the spacecraft attitude dynamics is reduced to a formally singular system with periodically varying parameters, which is quite different from a spacecraft with fixed appendages. In the framework of the singular control theory, the regularity and impulse-freeness of the singular system is analyzed and then admissible attitude controllers are designed by Lyapunov’s method. To improve the robustness against system uncertainties, an H∞ optimal control is designed by optimizing the H∞ norm of the system transfer function matrix. Comparative numerical experiments are performed to verify the theoretical results.

Comprehension of Spacecraft Telemetry Using Hierarchical Specifications of Behavior

Science.gov (United States)

Havelund, Klaus; Joshi, Rajeev

2014-01-01

A key challenge in operating remote spacecraft is that ground operators must rely on the limited visibility available through spacecraft telemetry in order to assess spacecraft health and operational status. We describe a tool for processing spacecraft telemetry that allows ground operators to impose structure on received telemetry in order to achieve a better comprehension of system state. A key element of our approach is the design of a domain-specific language that allows operators to express models of expected system behavior using partial specifications. The language allows behavior specifications with data fields, similar to other recent runtime verification systems. What is notable about our approach is the ability to develop hierarchical specifications of behavior. The language is implemented as an internal DSL in the Scala programming language that synthesizes rules from patterns of specification behavior. The rules are automatically applied to received telemetry and the inferred behaviors are available to ground operators using a visualization interface that makes it easier to understand and track spacecraft state. We describe initial results from applying our tool to telemetry received from the Curiosity rover currently roving the surface of Mars, where the visualizations are being used to trend subsystem behaviors, in order to identify potential problems before they happen. However, the technology is completely general and can be applied to any system that generates telemetry such as event logs.

Gravity Probe-B (GP-B) Mission and Tracking, Telemetry and Control Subsystem Overview

Science.gov (United States)

Kennedy, Paul; Bell, Joseph L. (Technical Monitor)

2001-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) in Huntsville, Alabama will launch the Gravity Probe B (GP-B) space experiment in the Fall of 2002. The GP-B spacecraft was developed to prove Einstein's theory of General Relativity. This paper will provide an overview of the GPB mission and will discuss the design, and test of the spacecraft Tracking, Telemetry and Control (TT&C) subsystem which incorporates NASA's latest generation standard transponder for use with the NASA Tracking and Data Relay Satellite System (TDRSS).

(abstract) ARGOS: a System to Monitor Ulysses Nutation and Thruster Firings from Variations of the Spacecraft Radio Signal

Science.gov (United States)

McElrath, T. P.; Cangahuala, L. A.; Miller, K. J.; Stravert, L. R.; Garcia-Perez, Raul

1995-01-01

Ulysses is a spin-stabilized spacecraft that experienced significant nutation after its launch in October 1990. This was due to the Sun-spacecraft-Earth geometry, and a study of the phenomenon predicted that the nutation would again be a problem during 1994-95. The difficulty of obtaining nutation estimates in real time from the spacecraft telemetry forced the ESA/NASA Ulysses Team to explore alternative information sources. The work performed by the ESA Operations Team provided a model for a system that uses the radio signal strength measurements to monitor the spacecraft dynamics. These measurements (referred to as AGC) are provided once per second by the tracking stations of the DSN. The system was named ARGOS (Attitude Reckoning from Ground Observable Signals) after the ever-vigilant, hundred-eyed giant of Greek Mythology. The ARGOS design also included Doppler processing, because Doppler shifts indicate thruster firings commanded by the active nutation control carried out onboard the spacecraft. While there is some visibility into thruster activity from telemetry, careful processing of the high-sample-rate Doppler data provides an accurate means of detecting the presence and time of thruster firings. DSN Doppler measurements are available at a ten-per-second rate in the same tracking data block as the AGC data.

A solar cycle of spacecraft anomalies due to internal charging

Directory of Open Access Journals (Sweden)

G. L. Wrenn

2002-07-01

Full Text Available It is important to appreciate how the morphology of internal charging of spacecraft systems, due to penetrating electrons, differs from that of the more common surface charging, due to electrons with lower energy. A specific and recurrent anomaly on a geostationary communication satellite has been tracked for ten years so that solar cycle and seasonal dependencies can be clearly established. Concurrent measurements of sunspot number, solar wind speed and 2-day >2 MeV electron fluence are presented to highlight pertinent space weather relationships, and the importance of understanding the complex particle interaction processes involved.Key words. Magnetospheric physics (energetic particles; trapped; solar wind – magnetosphere interactions – space plasma physics (spacecraft sheaths, wakes, charging

Systematic Examination of Stardust Bulbous Track Wall Materials

Science.gov (United States)

Nakamura-Messenger, K.; Clemett, S. J.; Nguyen, A. N.; Berger, E. L.; Keller, L. P.; Messenger, S.

2013-01-01

Analyses of Comet Wild-2 samples returned by NASA's Stardust spacecraft have focused primarily on terminal particles (TPs) or well-preserved fine-grained materials along the track walls [1,2]. However much of the collected material was melted and mixed intimately with the aerogel by the hypervelocity impact [3,4]. We are performing systematic examinations of entire Stardust tracks to establish the mineralogy and origins of all comet Wild 2 components [7,8]. This report focuses on coordinated analyses of indigenous crystalline and amorphous/melt cometary materials along the aerogel track walls, their interaction with aerogel during collection and comparisons with their TPs.

Role of TDRSS in tracking and data acquisition

Science.gov (United States)

Spearing, R. E.

1980-01-01

The integration and operation of the Tracking Data Relay Satellite System (TDRSS) into the NASA Communications Network (NASCOM) equipment and services is described. The system concept employs spacecraft in geosynchronous orbit, operating as communications front-ends, and a single ground terminal, which provides primary tracking and data acquisition services for earth-orbiting user satellites and for the Space Shuttle. The TDRSS system is further characterized by real-time throughput of user data and a high degree of automation.

A solar cycle of spacecraft anomalies due to internal charging

Directory of Open Access Journals (Sweden)

G. L. Wrenn

Full Text Available It is important to appreciate how the morphology of internal charging of spacecraft systems, due to penetrating electrons, differs from that of the more common surface charging, due to electrons with lower energy. A specific and recurrent anomaly on a geostationary communication satellite has been tracked for ten years so that solar cycle and seasonal dependencies can be clearly established. Concurrent measurements of sunspot number, solar wind speed and 2-day >2 MeV electron fluence are presented to highlight pertinent space weather relationships, and the importance of understanding the complex particle interaction processes involved.

Key words. Magnetospheric physics (energetic particles; trapped; solar wind – magnetosphere interactions – space plasma physics (spacecraft sheaths, wakes, charging

The Global Precipitation Measurement (GPM) Spacecraft Power System Design and Orbital Performance

Science.gov (United States)

Dakermanji, George; Burns, Michael; Lee, Leonine; Lyons, John; Kim, David; Spitzer, Thomas; Kercheval, Bradford

2016-01-01

The Global Precipitation Measurement (GPM) spacecraft was jointly developed by National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA). It is a Low Earth Orbit (LEO) spacecraft launched on February 27, 2014. The spacecraft is in a circular 400 Km altitude, 65 degrees inclination nadir pointing orbit with a three year basic mission life. The solar array consists of two sun tracking wings with cable wraps. The panels are populated with triple junction cells of nominal 29.5% efficiency. One axis is canted by 52 degrees to provide power to the spacecraft at high beta angles. The power system is a Direct Energy Transfer (DET) system designed to support 1950 Watts orbit average power. The batteries use SONY 18650HC cells and consist of three 8s x 84p batteries operated in parallel as a single battery. The paper describes the power system design details, its performance to date and the lithium ion battery model that was developed for use in the energy balance analysis and is being used to predict the on-orbit health of the battery.

FMT (Flight Software Memory Tracker) For Cassini Spacecraft-Software Engineering Using JAVA

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Kan, Edwin P.; Uffelman, Hal; Wax, Allan H.

1997-01-01

The software engineering design of the Flight Software Memory Tracker (FMT) Tool is discussed in this paper. FMT is a ground analysis software set, consisting of utilities and procedures, designed to track the flight software, i.e., images of memory load and updatable parameters of the computers on-board Cassini spacecraft. FMT is implemented in Java.

Spacecraft Line-of-Sight Stabilization Using LWIR Earth Signature

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Quadrelli, Marco B.; Piazzolla, Sabino

2012-01-01

The objective of this study is to investigate the potential of using the bright and near-uniform Earth infrared (or wavelength infrared, LWIR) signature as a stable reference for accurate (micro-rad or less) inertial pointing and tracking on-board an space vehicle, including the determination of the fundamental limits of applicability of the proposed method for space missions. We demonstrate sub-micro radian level pointing accuracy under a representative set of disturbances experienced by the spacecraft in orbit.

Spacecraft radiator systems

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Anderson, Grant A. (Inventor)

2012-01-01

A spacecraft radiator system designed to provide structural support to the spacecraft. Structural support is provided by the geometric "crescent" form of the panels of the spacecraft radiator. This integration of radiator and structural support provides spacecraft with a semi-monocoque design.

Neural network based satellite tracking for deep space applications

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Amoozegar, F.; Ruggier, C.

2003-01-01

The objective of this paper is to provide a survey of neural network trends as applied to the tracking of spacecrafts in deep space at Ka-band under various weather conditions and examine the trade-off between tracing accuracy and communication link performance.

Analysis of an Interplanetary Coronal Mass Ejection by a Spacecraft Radio Signal: A Case Study

Science.gov (United States)

Molera Calvés, G.; Kallio, E.; Cimo, G.; Quick, J.; Duev, D. A.; Bocanegra Bahamón, T.; Nickola, M.; Kharinov, M. A.; Mikhailov, A. G.

2017-11-01

Tracking radio communication signals from planetary spacecraft with ground-based telescopes offers the possibility to study the electron density and the interplanetary scintillation of the solar wind. Observations of the telemetry link of planetary spacecraft have been conducted regularly with ground antennae from the European Very Long Baseline Interferometry Network, aiming to study the propagation of radio signals in the solar wind at different solar elongations and distances from the Sun. We have analyzed the Mars Express spacecraft radio signal phase fluctuations while, based on a 3-D heliosphere plasma simulation, an interplanetary coronal mass ejection (ICME) crossed the radio path during one of our observations on 6 April 2015. Our measurements showed that the phase scintillation indices increased by a factor of 4 during the passage of the ICME. The method presented here confirms that the phase scintillation technique based on spacecraft signals provides information of the properties and propagation of the ICMEs in the heliosphere.

Laboratory Spacecraft Data Processing and Instrument Autonomy: AOSAT as Testbed

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Lightholder, Jack; Asphaug, Erik; Thangavelautham, Jekan

2015-11-01

Recent advances in small spacecraft allow for their use as orbiting microgravity laboratories (e.g. Asphaug and Thangavelautham LPSC 2014) that will produce substantial amounts of data. Power, bandwidth and processing constraints impose limitations on the number of operations which can be performed on this data as well as the data volume the spacecraft can downlink. We show that instrument autonomy and machine learning techniques can intelligently conduct data reduction and downlink queueing to meet data storage and downlink limitations. As small spacecraft laboratory capabilities increase, we must find techniques to increase instrument autonomy and spacecraft scientific decision making. The Asteroid Origins Satellite (AOSAT) CubeSat centrifuge will act as a testbed for further proving these techniques. Lightweight algorithms, such as connected components analysis, centroid tracking, K-means clustering, edge detection, convex hull analysis and intelligent cropping routines can be coupled with the tradition packet compression routines to reduce data transfer per image as well as provide a first order filtering of what data is most relevant to downlink. This intelligent queueing provides timelier downlink of scientifically relevant data while reducing the amount of irrelevant downlinked data. Resulting algorithms allow for scientists to throttle the amount of data downlinked based on initial experimental results. The data downlink pipeline, prioritized for scientific relevance based on incorporated scientific objectives, can continue from the spacecraft until the data is no longer fruitful. Coupled with data compression and cropping strategies at the data packet level, bandwidth reductions exceeding 40% can be achieved while still downlinking data deemed to be most relevant in a double blind study between scientist and algorithm. Applications of this technology allow for the incorporation of instrumentation which produces significant data volumes on small spacecraft

Quaternion-based adaptive output feedback attitude control of spacecraft using Chebyshev neural networks.

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Zou, An-Min; Dev Kumar, Krishna; Hou, Zeng-Guang

2010-09-01

This paper investigates the problem of output feedback attitude control of an uncertain spacecraft. Two robust adaptive output feedback controllers based on Chebyshev neural networks (CNN) termed adaptive neural networks (NN) controller-I and adaptive NN controller-II are proposed for the attitude tracking control of spacecraft. The four-parameter representations (quaternion) are employed to describe the spacecraft attitude for global representation without singularities. The nonlinear reduced-order observer is used to estimate the derivative of the spacecraft output, and the CNN is introduced to further improve the control performance through approximating the spacecraft attitude motion. The implementation of the basis functions of the CNN used in the proposed controllers depends only on the desired signals, and the smooth robust compensator using the hyperbolic tangent function is employed to counteract the CNN approximation errors and external disturbances. The adaptive NN controller-II can efficiently avoid the over-estimation problem (i.e., the bound of the CNNs output is much larger than that of the approximated unknown function, and hence, the control input may be very large) existing in the adaptive NN controller-I. Both adaptive output feedback controllers using CNN can guarantee that all signals in the resulting closed-loop system are uniformly ultimately bounded. For performance comparisons, the standard adaptive controller using the linear parameterization of spacecraft attitude motion is also developed. Simulation studies are presented to show the advantages of the proposed CNN-based output feedback approach over the standard adaptive output feedback approach.

Dynamic sensor tasking and IMM EKF estimation for tracking impulsively maneuvering satellites

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Lace, Arthur A.

In order to efficiently maintain space situational awareness, care must be taken to optimally allocate expensive observation resources. In most situations the available sensors capable of tracking spacecraft have their time split between many different monitoring responsibilities. Tracking maneuvering spacecraft can be especially difficult as the schedule of maneuvers may not be known and will often throw off previous orbital models. Effectively solving this tasking problem is an ongoing focus of research in the area of space situational awareness. Most methods of automated tasking do not make use of interacting multiple model extended Kalman filter techniques to better track satellites during maneuvers. This paper proposes a modification to a Fisher information gain and estimated state covariance based sensor tasking method to take maneuver probability and multiple model dynamics into account. By incorporating the probabilistic maneuvering model, sensor tasking can be improved during satellite maneuvers using constrained resources. The proposed methods are verified through the use of numerical simulations with multiple maneuvering satellites and both orbital and ground-based sensors.

Relativistic effects of spacecraft with circumnavigating observer

Science.gov (United States)

Shanklin, Nathaniel; West, Joseph

A variation of the recently introduced Trolley Paradox, itself is a variation of the Ehrenfest Paradox is presented. In the Trolley Paradox, a ``stationary'' set of observers tracking a wheel rolling with a constant velocity find that the wheel travels further than its rest length circumference during one revolution of the wheel, despite the fact that the Lorentz contracted circumference is less than its rest value. In the variation presented, a rectangular spacecraft with onboard observers moves with constant velocity and is circumnavigated by several small ``sloops'' forming teams of inertial observers. This whole precession moves relative to a set of ``stationary'' Earth observers. Two cases are presented, one in which the sloops are evenly spaced according to the spacecraft observers, and one in which the sloops are evenly spaced according to the Earth observes. These two cases, combined with the rectangular geometry and an emphasis on what is seen by, and what is measured by, each set of observers is very helpful in sorting out the apparent contradictions. To aid in the visualizations stationary representations in excel along with animation in Visual Python and Unity are presented. The analysis presented is suitable for undergraduate physics majors.

Spacecraft Charging and the Microwave Anisotropy Probe Spacecraft

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Timothy, VanSant J.; Neergaard, Linda F.

1998-01-01

The Microwave Anisotropy Probe (MAP), a MIDEX mission built in partnership between Princeton University and the NASA Goddard Space Flight Center (GSFC), will study the cosmic microwave background. It will be inserted into a highly elliptical earth orbit for several weeks and then use a lunar gravity assist to orbit around the second Lagrangian point (L2), 1.5 million kilometers, anti-sunward from the earth. The charging environment for the phasing loops and at L2 was evaluated. There is a limited set of data for L2; the GEOTAIL spacecraft measured relatively low spacecraft potentials (approx. 50 V maximum) near L2. The main area of concern for charging on the MAP spacecraft is the well-established threat posed by the "geosynchronous region" between 6-10 Re. The launch in the autumn of 2000 will coincide with the falling of the solar maximum, a period when the likelihood of a substorm is higher than usual. The likelihood of a substorm at that time has been roughly estimated to be on the order of 20% for a typical MAP mission profile. Because of the possibility of spacecraft charging, a requirement for conductive spacecraft surfaces was established early in the program. Subsequent NASCAP/GEO analyses for the MAP spacecraft demonstrated that a significant portion of the sunlit surface (solar cell cover glass and sunshade) could have nonconductive surfaces without significantly raising differential charging. The need for conductive materials on surfaces continually in eclipse has also been reinforced by NASCAP analyses.

Navigating the MESSENGER Spacecraft through End of Mission

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Bryan, C. G.; Williams, B. G.; Williams, K. E.; Taylor, A. H.; Carranza, E.; Page, B. R.; Stanbridge, D. R.; Mazarico, E.; Neumann, G. A.; O'Shaughnessy, D. J.; McAdams, J. V.; Calloway, A. B.

2015-12-01

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited the planet Mercury from March 2011 until the end of April 2015, when it impacted the planetary surface after propellant reserves used to maintain the orbit were depleted. This highly successful mission was led by the principal investigator, Sean C. Solomon, of Columbia University. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) designed and assembled the spacecraft and served as the home for spacecraft operations. Spacecraft navigation for the entirety of the mission was provided by the Space Navigation and Flight Dynamics Practice (SNAFD) of KinetX Aerospace. Orbit determination (OD) solutions were generated through processing of radiometric tracking data provided by NASA's Deep Space Network (DSN) using the MIRAGE suite of orbital analysis tools. The MESSENGER orbit was highly eccentric, with periapsis at a high northern latitude and periapsis altitude in the range 200-500 km for most of the orbital mission phase. In a low-altitude "hover campaign" during the final two months of the mission, periapsis altitudes were maintained within a narrow range between about 35 km and 5 km. Navigating a spacecraft so near a planetary surface presented special challenges. Tasks required to meet those challenges included the modeling and estimation of Mercury's gravity field and of solar and planetary radiation pressure, and the design of frequent orbit-correction maneuvers. Superior solar conjunction also presented observational modeling issues. One key to the overall success of the low-altitude hover campaign was a strategy to utilize data from an onboard laser altimeter as a cross-check on the navigation team's reconstructed and predicted estimates of periapsis altitude. Data obtained from the Mercury Laser Altimeter (MLA) on a daily basis provided near-real-time feedback that proved invaluable in evaluating alternative orbit estimation strategies, and

Superimposed disturbance in the ionosphere triggered by spacecraft launches in China

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He, L. M.; Wu, L. X.; Liu, S. J.; Liu, S. N.

2015-11-01

Using GPS dual-frequency observations collected by continuously operating GPS tracking stations in China, superimposed disturbances caused by the integrated action of spacecraft's physical effect and chemical effect on ionosphere during the launches of the spacecrafts Tiangong-1 and Shenzhou-8 in China were firstly determined. The results show that the superimposed disturbance was composed of remarkable ionospheric waves and significant ionospheric depletion emerged after both launches. Meanwhile, we found for the first time that the ionospheric waves were made up of two periods of wave by wavelet analysis. The first period of ∼ 4 min shows one event in the near stations and two sub-events in the few far stations. The second period of ∼ 9 min shows only one event in all the observed stations. Finally, the time characteristics for ionospheric waves and depletions were examined.

Superimposed disturbance in the ionosphere triggered by spacecraft launches in China

Directory of Open Access Journals (Sweden)

L. M. He

2015-11-01

Full Text Available Using GPS dual-frequency observations collected by continuously operating GPS tracking stations in China, superimposed disturbances caused by the integrated action of spacecraft's physical effect and chemical effect on ionosphere during the launches of the spacecrafts Tiangong-1 and Shenzhou-8 in China were firstly determined. The results show that the superimposed disturbance was composed of remarkable ionospheric waves and significant ionospheric depletion emerged after both launches. Meanwhile, we found for the first time that the ionospheric waves were made up of two periods of wave by wavelet analysis. The first period of ∼ 4 min shows one event in the near stations and two sub-events in the few far stations. The second period of ∼ 9 min shows only one event in all the observed stations. Finally, the time characteristics for ionospheric waves and depletions were examined.

Spacecraft Charge Monitor

Science.gov (United States)

Goembel, L.

2003-12-01

We are currently developing a flight prototype Spacecraft Charge Monitor (SCM) with support from NASA's Small Business Innovation Research (SBIR) program. The device will use a recently proposed high energy-resolution electron spectroscopic technique to determine spacecraft floating potential. The inspiration for the technique came from data collected by the Atmosphere Explorer (AE) satellites in the 1970s. The data available from the AE satellites indicate that the SCM may be able to determine spacecraft floating potential to within 0.1 V under certain conditions. Such accurate measurement of spacecraft charge could be used to correct biases in space plasma measurements. The device may also be able to measure spacecraft floating potential in the solar wind and in orbit around other planets.

METRIC: A Dedicated Earth-Orbiting Spacecraft for Investigating Gravitational Physics and the Space Environment

Directory of Open Access Journals (Sweden)

Roberto Peron

2017-07-01

Full Text Available 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 accelerometer.

Miniaturized star tracker for micro spacecraft with high angular rate

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Li, Jianhua; Li, Zhifeng; Niu, Zhenhong; Liu, Jiaqi

2017-10-01

There is a clear need for miniaturized, lightweight, accurate and inexpensive star tracker for spacecraft with large anglar rate. To face these new constraints, the Beijing Institute of Space Long March Vehicle has designed, built and flown a low cost miniaturized star tracker that provides autonomous ("Lost in Space") inertial attitude determination, 2 Hz 3-axis star tracking, and digital imaging with embedded compression. Detector with high sensitivity is adopted to meet the dynamic and miniature requirement. A Sun and Moon avoiding method based on the calculation of Sun and Moon's vector by astronomical theory is proposed. The produced prototype weight 0.84kg, and can be used for a spacecraft with 6°/s anglar rate. The average angle measure error is less than 43 arc second. The ground verification and application of the star tracker during the pick-up flight test showed that the capability of the product meet the requirement.

Robust Tracking Control for Rendezvous in Near-Circular Orbits

Directory of Open Access Journals (Sweden)

Neng Wan

2013-01-01

Full Text Available This paper investigates a robust guaranteed cost tracking control problem for thrust-limited spacecraft rendezvous in near-circular orbits. Relative motion model is established based on the two-body problem with noncircularity of the target orbit described as a parameter uncertainty. A guaranteed cost tracking controller with input saturation is designed via a linear matrix inequality (LMI method, and sufficient conditions for the existence of the robust tracking controller are derived, which is more concise and less conservative compared with the previous works. Numerical examples are provided for both time-invariant and time-variant reference signals to illustrate the effectiveness of the proposed control scheme when applied to the terminal rendezvous and other astronautic missions with scheduled states signal.

Adaptive nonlinear robust relative pose control of spacecraft autonomous rendezvous and proximity operations.

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Sun, Liang; Huo, Wei; Jiao, Zongxia

2017-03-01

This paper studies relative pose control for a rigid spacecraft with parametric uncertainties approaching to an unknown tumbling target in disturbed space environment. State feedback controllers for relative translation and relative rotation are designed in an adaptive nonlinear robust control framework. The element-wise and norm-wise adaptive laws are utilized to compensate the parametric uncertainties of chaser and target spacecraft, respectively. External disturbances acting on two spacecraft are treated as a lumped and bounded perturbation input for system. To achieve the prescribed disturbance attenuation performance index, feedback gains of controllers are designed by solving linear matrix inequality problems so that lumped disturbance attenuation with respect to the controlled output is ensured in the L 2 -gain sense. Moreover, in the absence of lumped disturbance input, asymptotical convergence of relative pose are proved by using the Lyapunov method. Numerical simulations are performed to show that position tracking and attitude synchronization are accomplished in spite of the presence of couplings and uncertainties. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Calibration of the KA Band Tracking of the Bepi-Colombo Spacecraft (more Experiment)

Science.gov (United States)

Barriot, J.; Serafini, J.; Sichoix, L.

2013-12-01

The radiosciences Bepi-Colombo MORE experiment will use X/X, X/Ka and Ka/Ka band radio links to make accurate measurements of the spacecraft range and range rate. Tropospheric zenith wet delays range from 1.5 cm to 10 cm, with high variability (less than 1000 s) and will impair these accurate measurements. Conditions vary from summer (worse) to winter (better), from day (worse) to night (better). These wet delays cannot be estimated from ground weather measurements and alternative calibration methods should be used in order to cope with the MORE requirements (no more than 3 mm at 1000 s). Due to the Mercury orbit, MORE measurements will be performed by daylight and more frequently in summer than in winter (from Northern hemisphere). Two systems have been considered to calibrate this wet delay: Water Vapor Radiometers (WVRs) and GPS receivers. The Jet Propulsion Laboratory has developed a new class of WVRs reaching a 5 percent accuracy for the wet delay calibration (0.75 mm to 5 mm), but these WVRs are expensive to build and operate. GPS receivers are also routinely used for the calibration of data from NASA Deep Space probes, but several studies have shown that GPS receivers can give good calibration (through wet delay mapping functions) for long time variations, but are not accurate enough for short time variations (100 to 1000 s), and that WVRs must be used to efficiently calibrate the wet troposphere delays over such time spans. We think that such a calibration could be done by assimilating data from all the GNSS constellations (GPS, GLONASS, Galileo, Beidou and IRNSS) that will be available at the time of the Bepi-Colombo arrival at Mercury (2021), provided that the underlying physics of the turbulent atmosphere and evapotranspiration processes are properly taken into account at such time scales. This implies to do a tomographic image of the troposphere overlying each Deep Space tracking station at time scales of less than 1000 s. For this purpose, we have

SeaTrack: Ground station orbit prediction and planning software for sea-viewing satellites

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Lambert, Kenneth S.; Gregg, Watson W.; Hoisington, Charles M.; Patt, Frederick S.

1993-01-01

An orbit prediction software package (Sea Track) was designed to assist High Resolution Picture Transmission (HRPT) stations in the acquisition of direct broadcast data from sea-viewing spacecraft. Such spacecraft will be common in the near future, with the launch of the Sea viewing Wide Field-of-view Sensor (SeaWiFS) in 1994, along with the continued Advanced Very High Resolution Radiometer (AVHRR) series on NOAA platforms. The Brouwer-Lyddane model was chosen for orbit prediction because it meets the needs of HRPT tracking accuracies, provided orbital elements can be obtained frequently (up to within 1 week). Sea Track requires elements from the U.S. Space Command (NORAD Two-Line Elements) for the satellite's initial position. Updated Two-Line Elements are routinely available from many electronic sources (some are listed in the Appendix). Sea Track is a menu-driven program that allows users to alter input and output formats. The propagation period is entered by a start date and end date with times in either Greenwich Mean Time (GMT) or local time. Antenna pointing information is provided in tabular form and includes azimuth/elevation pointing angles, sub-satellite longitude/latitude, acquisition of signal (AOS), loss of signal (LOS), pass orbit number, and other pertinent pointing information. One version of Sea Track (non-graphical) allows operation under DOS (for IBM-compatible personal computers) and UNIX (for Sun and Silicon Graphics workstations). A second, graphical, version displays orbit tracks, and azimuth-elevation for IBM-compatible PC's, but requires a VGA card and Microsoft FORTRAN.

GPS-based tracking system for TOPEX orbit determination

Science.gov (United States)

Melbourne, W. G.

1984-01-01

A tracking system concept is discussed that is based on the utilization of the constellation of Navstar satellites in the Global Positioning System (GPS). The concept involves simultaneous and continuous metric tracking of the signals from all visible Navstar satellites by approximately six globally distributed ground terminals and by the TOPEX spacecraft at 1300-km altitude. Error studies indicate that this system could be capable of obtaining decimeter position accuracies and, most importantly, around 5 cm in the radial component which is key to exploiting the full accuracy potential of the altimetric measurements for ocean topography. Topics covered include: background of the GPS, the precision mode for utilization of the system, past JPL research for using the GPS in precision applications, the present tracking system concept for high accuracy satellite positioning, and results from a proof-of-concept demonstration.

Probing the earth's gravity field by means of satellite-to-satellite tracking

Science.gov (United States)

Vonbun, F. O.

1977-01-01

Two satellite-to-satellite tracking (sst) tests are described in detail: (1) the ATS-6/Geos-3 and (2) the ATS-6/Apollo-Soyuz experiment. The main purpose of these two experiments was to track via ATS-6 the Geos-3, as well as the Apollo-Soyuz and to use these tracking data to determine both of the orbits at the same time, each of the orbits alone, and to test the two sst links to study local gravity anomalies. A second purpose was to test communications, command and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground.

Tracking and Data Relay Satellite System /TDRSS/ telecommunication services

Science.gov (United States)

Deerkoski, L. F.

1975-01-01

The TDRSS and tracking services define the telecommunication performance of the TDRSS between the RF interface with user spacecraft and the data interface with NASCOM at the ground terminal. Attention is given to system constraints, forward link services, multiple-access signal design parameters, S-band single access signal design parameters, multiple-access return link services, and single-access return link services.

Acquisition, tracking, and pointing IV; Proceedings of the Meeting, Orlando, FL, Apr. 19, 20, 1990

Science.gov (United States)

Gowrinathan, Sankaran

1990-09-01

Various papers on acquisition, tracking, and pointing are presented. Individual topics addressed include: backlash control techniques in geared servo mechanics; optical fiber and photodetector array for robotic seam tracking; star trackers for spacecraft applications; Starfire optical range tracking system for the 1.5 m telescope; real-time video image centroid tracker; optical alignment with a beamwalk system; line-of-sight stabilization requirements for target tracking system; image quality with narrow beam illumination in an active tracking system; IR sensor data fusion for target detection, identification, and tracking; target location and pointing algorithm for a three-axis stabilized line scanner. Also discussed are: adaptive control system techniques applied to inertial stabilization systems; supervisory control of electrooptic tracking and pointing; position loop compensation for flex-pivot-mounted gimbal stabilization systems; advanced testing methods for acquisition, tracking, and pointing; development of kinmatics for gimballed mirror systems.

Orbit-attitude coupled motion around small bodies: Sun-synchronous orbits with Sun-tracking attitude motion

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Kikuchi, Shota; Howell, Kathleen C.; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

2017-11-01

The motion of a spacecraft in proximity to a small body is significantly perturbed due to its irregular gravity field and solar radiation pressure. In such a strongly perturbed environment, the coupling effect of the orbital and attitude motions exerts a large influence that cannot be neglected. However, natural orbit-attitude coupled dynamics around small bodies that are stationary in both orbital and attitude motions have yet to be observed. The present study therefore investigates natural coupled motion that involves both a Sun-synchronous orbit and Sun-tracking attitude motion. This orbit-attitude coupled motion enables a spacecraft to maintain its orbital geometry and attitude state with respect to the Sun without requiring active control. Therefore, the proposed method can reduce the use of an orbit and attitude control system. This paper first presents analytical conditions to achieve Sun-synchronous orbits and Sun-tracking attitude motion. These analytical solutions are then numerically propagated based on non-linear coupled orbit-attitude equations of motion. Consequently, the possibility of implementing Sun-synchronous orbits with Sun-tracking attitude motion is demonstrated.

Using the Global Positioning System for Earth Orbiter and Deep Space Tracking

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Lichten, Stephen M.

1994-01-01

The Global Positioning System (GPS) can play a major role in supporting orbit and trajectory determination for spacecraft in a wide range of applications, including low-Earth, high-Earth, and even deep space (interplanetary) tracking. This paper summarizes recent results demonstrating these unique and far-ranging applications of GPS.

Consensus seeking, formation keeping, and trajectory tracking in multiple vehicle cooperative control

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Ren, Wei

Cooperative control problems for multiple vehicle systems can be categorized as either formation control problems with applications to mobile robots, unmanned air vehicles, autonomous underwater vehicles, satellites, aircraft, spacecraft, and automated highway systems, or non-formation control problems such as task assignment, cooperative transport, cooperative role assignment, air traffic control, cooperative timing, and cooperative search. The cooperative control of multiple vehicle systems poses significant theoretical and practical challenges. For cooperative control strategies to be successful, numerous issues must be addressed. We consider three important and correlated issues: consensus seeking, formation keeping, and trajectory tracking. For consensus seeking, we investigate algorithms and protocols so that a team of vehicles can reach consensus on the values of the coordination data in the presence of imperfect sensors, communication dropout, sparse communication topologies, and noisy and unreliable communication links. The main contribution of this dissertation in this area is that we show necessary and/or sufficient conditions for consensus seeking with limited, unidirectional, and unreliable information exchange under fixed and switching interaction topologies (through either communication or sensing). For formation keeping, we apply a so-called "virtual structure" approach to spacecraft formation flying and multi-vehicle formation maneuvers. As a result, single vehicle path planning and trajectory generation techniques can be employed for the virtual structure while trajectory tracking strategies can be employed for each vehicle. The main contribution of this dissertation in this area is that we propose a decentralized architecture for multiple spacecraft formation flying in deep space with formation feedback introduced. This architecture ensures the necessary precision in the presence of actuator saturation, internal and external disturbances, and

Magnetic Launch Assist Experimental Track

Science.gov (United States)

1999-01-01

In this photograph, a futuristic spacecraft model sits atop a carrier on the Magnetic Launch Assist System, formerly known as the Magnetic Levitation (MagLev) System, experimental track at the Marshall Space Flight Center (MSFC). Engineers at MSFC have developed and tested Magnetic Launch Assist technologies that would use magnetic fields to levitate and accelerate a vehicle along a track at very high speeds. Similar to high-speed trains and roller coasters that use high-strength magnets to lift and propel a vehicle a couple of inches above a guideway, a Magnetic Launch Assist system would electromagnetically drive a space vehicle along the track. A full-scale, operational track would be about 1.5-miles long and capable of accelerating a vehicle to 600 mph in 9.5 seconds. This track is an advanced linear induction motor. Induction motors are common in fans, power drills, and sewing machines. Instead of spinning in a circular motion to turn a shaft or gears, a linear induction motor produces thrust in a straight line. Mounted on concrete pedestals, the track is 100-feet long, about 2-feet wide, and about 1.5-feet high. The major advantages of launch assist for NASA launch vehicles is that it reduces the weight of the take-off, the landing gear, the wing size, and less propellant resulting in significant cost savings. The US Navy and the British MOD (Ministry of Defense) are planning to use magnetic launch assist for their next generation aircraft carriers as the aircraft launch system. The US Army is considering using this technology for launching target drones for anti-aircraft training.

The trajectory prediction of spacecraft by grey method

International Nuclear Information System (INIS)

Wang, Qiyue; Wang, Zhongyu; Zhang, Zili; Wang, Yanqing; Zhou, Weihu

2016-01-01

The real-time and high-precision trajectory prediction of a moving object is a core technology in the field of aerospace engineering. The real-time monitoring and tracking technology are also significant guarantees of aerospace equipment. A dynamic trajectory prediction method called grey dynamic filter (GDF) which combines the dynamic measurement theory and grey system theory is proposed. GDF can use coordinates of the current period to extrapolate coordinates of the following period. At meantime, GDF can also keep the instantaneity of measured coordinates by the metabolism model. In this paper the optimal model length of GDF is firstly selected to improve the prediction accuracy. Then the simulation for uniformly accelerated motion and variably accelerated motion is conducted. The simulation results indicate that the mean composite position error of GDF prediction is one-fifth to that of Kalman filter (KF). By using a spacecraft landing experiment, the prediction accuracy of GDF is compared with the KF method and the primitive grey method (GM). The results show that the motion trajectory of spacecraft predicted by GDF is much closer to actual trajectory than the other two methods. The mean composite position error calculated by GDF is one-eighth to KF and one-fifth to GM respectively. (paper)

Optimal Electrical Energy Slewing for Reaction Wheel Spacecraft

Science.gov (United States)

Marsh, Harleigh Christian

method is adopted in this dissertation to transform the nonsmooth minimum electrical energy problem into an equivalent smooth formulation, which then allows standard techniques in optimal control to solve and analyze the problem. Through numerically solving families of optimal control problems, the relationship between electrical energy and transfer time is identified and explored for both off-and on-eigenaxis maneuvering, under minimum dissipative losses as well as under minimum electrical energy. A trade space between on-and off-eigenaxis maneuvering is identified, from which is shown that agile near time optimal maneuvers exist within the energy budget associated with conventional eigenaxis maneuvering. Moreover, even for conventional eigenaxis maneuvering, energy requirements can be dramatically reduced by maneuvering off-eigenaxis. These results address one of the fundamental assumptions in the field of optimal path design verses conventional maneuver design. Two practical flight situations are addressed in this dissertation in regards to reducing energy and power: The case when the attitude of the spacecraft is predetermined, and the case where reaction wheels can not be directly controlled. For the setting where the attitude of spacecraft is on a predefined trajectory, it is demonstrated that reduced energy maneuvers are only attainable though the application of null-motions, which requires control of the reaction wheels. A computationally light formulation is developed minimizing the dissipative losses through the application of null motions. In the situation where the reaction wheels can not be directly controlled, it is demonstrated that energy consumption, dissipative losses, and peak-power loads, of the reaction-wheel array can each be reduced substantially by controlling the input to the attitude control system through attitude steering. It is demonstrated that the open loop trajectories correctly predict the closed loop response when tracked by an attitude

Maneuver Planning for Conjunction Risk Mitigation with Ground-track Control Requirements

Science.gov (United States)

McKinley, David

2008-01-01

The planning of conjunction Risk Mitigation Maneuvers (RMM) in the presence of ground-track control requirements is analyzed. Past RMM planning efforts on the Aqua, Aura, and Terra spacecraft have demonstrated that only small maneuvers are available when ground-track control requirements are maintained. Assuming small maneuvers, analytical expressions for the effect of a given maneuver on conjunction geometry are derived. The analytical expressions are used to generate a large trade space for initial RMM design. This trade space represents a significant improvement in initial maneuver planning over existing methods that employ high fidelity maneuver models and propagation.

Feasibility of infrared Earth tracking for deep-space optical communications.

Science.gov (United States)

Chen, Yijiang; Hemmati, Hamid; Ortiz, Gerry G

2012-01-01

Infrared (IR) Earth thermal tracking is a viable option for optical communications to distant planet and outer-planetary missions. However, blurring due to finite receiver aperture size distorts IR Earth images in the presence of Earth's nonuniform thermal emission and limits its applicability. We demonstrate a deconvolution algorithm that can overcome this limitation and reduce the error from blurring to a negligible level. The algorithm is applied successfully to Earth thermal images taken by the Mars Odyssey spacecraft. With the solution to this critical issue, IR Earth tracking is established as a viable means for distant planet and outer-planetary optical communications. © 2012 Optical Society of America

GSFC network operations with Tracking and Data Relay Satellites

Science.gov (United States)

Spearing, R.; Perreten, D. E.

The Tracking and Data Relay Satellite System (TDRSS) Network (TN) has been developed to provide services to all NASA User spacecraft in near-earth orbits. Three inter-relating entities will provide these services. The TN has been transformed from a network continuously changing to meet User specific requirements to a network which is flexible to meet future needs without significant changes in operational concepts. Attention is given to the evolution of the TN network, the TN capabilities-space segment, forward link services, tracking services, return link services, the three basic capabilities, single access services, multiple access services, simulation services, the White Sands Ground Terminal, the NASA communications network, and the network control center.

Three-dimensional modeling, estimation, and fault diagnosis of spacecraft air contaminants.

Science.gov (United States)

Narayan, A P; Ramirez, W F

1998-01-01

A description is given of the design and implementation of a method to track the presence of air contaminants aboard a spacecraft using an accurate physical model and of a procedure that would raise alarms when certain tolerance levels are exceeded. Because our objective is to monitor the contaminants in real time, we make use of a state estimation procedure that filters measurements from a sensor system and arrives at an optimal estimate of the state of the system. The model essentially consists of a convection-diffusion equation in three dimensions, solved implicitly using the principle of operator splitting, and uses a flowfield obtained by the solution of the Navier-Stokes equations for the cabin geometry, assuming steady-state conditions. A novel implicit Kalman filter has been used for fault detection, a procedure that is an efficient way to track the state of the system and that uses the sparse nature of the state transition matrices.

Application of Space Environmental Observations to Spacecraft Pre-Launch Engineering and Spacecraft Operations

Science.gov (United States)

Barth, Janet L.; Xapsos, Michael

2008-01-01

This presentation focuses on the effects of the space environment on spacecraft systems and applying this knowledge to spacecraft pre-launch engineering and operations. Particle radiation, neutral gas particles, ultraviolet and x-rays, as well as micrometeoroids and orbital debris in the space environment have various effects on spacecraft systems, including degradation of microelectronic and optical components, physical damage, orbital decay, biasing of instrument readings, and system shutdowns. Space climate and weather must be considered during the mission life cycle (mission concept, mission planning, systems design, and launch and operations) to minimize and manage risk to both the spacecraft and its systems. A space environment model for use in the mission life cycle is presented.

Benefits of Spacecraft Level Vibration Testing

Science.gov (United States)

Gordon, Scott; Kern, Dennis L.

2015-01-01

NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

Small Spacecraft for Planetary Science

Science.gov (United States)

Baker, John; Castillo-Rogez, Julie; Bousquet, Pierre-W.; Vane, Gregg; Komarek, Tomas; Klesh, Andrew

2016-07-01

As planetary science continues to explore new and remote regions of the Solar system with comprehensive and more sophisticated payloads, small spacecraft offer the possibility for focused and more affordable science investigations. These small spacecraft or micro spacecraft (attitude control and determination, capable computer and data handling, and navigation are being met by technologies currently under development to be flown on CubeSats within the next five years. This paper will discuss how micro spacecraft offer an attractive alternative to accomplish specific science and technology goals and what relevant technologies are needed for these these types of spacecraft. Acknowledgements: Part of this work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to NASA. Government sponsorship acknowledged.

A computer graphics pilot project - Spacecraft mission support with an interactive graphics workstation

Science.gov (United States)

Hagedorn, John; Ehrner, Marie-Jacqueline; Reese, Jodi; Chang, Kan; Tseng, Irene

1986-01-01

The NASA Computer Graphics Pilot Project was undertaken to enhance the quality control, productivity and efficiency of mission support operations at the Goddard Operations Support Computing Facility. The Project evolved into a set of demonstration programs for graphics intensive simulated control room operations, particularly in connection with the complex space missions that began in the 1980s. Complex mission mean more data. Graphic displays are a means to reduce the probabilities of operator errors. Workstations were selected with 1024 x 768 pixel color displays controlled by a custom VLSI chip coupled to an MC68010 chip running UNIX within a shell that permits operations through the medium of mouse-accessed pulldown window menus. The distributed workstations run off a host NAS 8040 computer. Applications of the system for tracking spacecraft orbits and monitoring Shuttle payload handling illustrate the system capabilities, noting the built-in capabilities of shifting the point of view and rotating and zooming in on three-dimensional views of spacecraft.

Computer simulation of spacecraft/environment interaction

International Nuclear Information System (INIS)

Krupnikov, K.K.; Makletsov, A.A.; Mileev, V.N.; Novikov, L.S.; Sinolits, V.V.

1999-01-01

This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language

Computer simulation of spacecraft/environment interaction

CERN Document Server

Krupnikov, K K; Mileev, V N; Novikov, L S; Sinolits, V V

1999-01-01

This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.

Monitoring on board spacecraft by means of passive detectors

International Nuclear Information System (INIS)

Ambrozova, I.; Brabcova, K.; Spurny, F.; Shurshakov, V. A.; Kartsev, I. S.; Tolochek, R. V.

2011-01-01

To estimate the radiation risk of astronauts during space missions, it is necessary to measure dose characteristics in various compartments of the spacecraft; this knowledge can be further used for estimating the health hazard in planned missions. This contribution presents results obtained during several missions on board the International Space Station (ISS) during 2005-09. A combination of thermoluminescent and plastic nuclear track detectors was used to measure the absorbed dose and dose equivalent. These passive detectors have several advantages, especially small dimensions, which enabled their placement at various locations in different compartments inside the ISS or inside the phantom. Variation of dosimetric quantities with the phase of the solar cycle and the position inside the ISS is discussed. (authors)

Sampled-Data Control of Spacecraft Rendezvous with Discontinuous Lyapunov Approach

Directory of Open Access Journals (Sweden)

Zhuoshi Li

2013-01-01

Full Text Available This paper investigates the sampled-data stabilization problem of spacecraft relative positional holding with improved Lyapunov function approach. The classical Clohessy-Wiltshire equation is adopted to describe the relative dynamic model. The relative position holding problem is converted into an output tracking control problem using sampling signals. A time-dependent discontinuous Lyapunov functionals approach is developed, which will lead to essentially less conservative results for the stability analysis and controller design of the corresponding closed-loop system. Sufficient conditions for the exponential stability analysis and the existence of the proposed controller are provided, respectively. Finally, a simulation result is established to illustrate the effectiveness of the proposed control scheme.

Lightweight Battery Charge Regulator Used to Track Solar Array Peak Power

Science.gov (United States)

Soeder, James F.; Button, Robert M.

1999-01-01

A battery charge regulator based on the series-connected boost regulator (SCBR) technology has been developed for high-voltage spacecraft applications. The SCBR regulates the solar array power during insolation to prevent battery overcharge or undercharge conditions. It can also be used to provide regulated battery output voltage to spacecraft loads if necessary. This technology uses industry-standard dc-dc converters and a unique interconnection to provide size, weight, efficiency, fault tolerance, and modularity benefits over existing systems. The high-voltage SCBR shown in the photograph has demonstrated power densities of over 1000 watts per kilogram (W/kg). Using four 150-W dc-dc converter modules, it can process 2500 W of power at 120 Vdc with a minimum input voltage of 90 Vdc. Efficiency of the SCBR was 94 to 98 percent over the entire operational range. Internally, the unit is made of two separate SCBR s, each with its own analog control circuitry, to demonstrate the modularity of the technology. The analog controllers regulate the output current and incorporate the output voltage limit with active current sharing between the two units. They also include voltage and current telemetry, on/off control, and baseplate temperature sensors. For peak power tracking, the SCBR was connected to a LabView-based data acquisition system for telemetry and control. A digital control algorithm for tracking the peak power point of a solar array was developed using the principle of matching the source impedance with the load impedance for maximum energy transfer. The algorithm was successfully demonstrated in a simulated spacecraft electrical system at the Boeing PhantomWorks High Voltage Test Facility in Seattle, Washington. The system consists of a 42-string, high-voltage solar array simulator, a 77-cell, 80-ampere-hour (A-hr) nickel-hydrogen battery, and a constant power-load module. The SCBR and the LabView control algorithm successfully tracked the solar array peak

Four-spacecraft determination of magnetopause orientation, motion and thickness: comparison with results from single-spacecraft methods

Directory of Open Access Journals (Sweden)

S. E. Haaland

2004-04-01

Full Text Available In this paper, we use Cluster data from one magnetopause event on 5 July 2001 to compare predictions from various methods for determination of the velocity, orientation, and thickness of the magnetopause current layer. We employ established as well as new multi-spacecraft techniques, in which time differences between the crossings by the four spacecraft, along with the duration of each crossing, are used to calculate magnetopause speed, normal vector, and width. The timing is based on data from either the Cluster Magnetic Field Experiment (FGM or the Electric Field Experiment (EFW instruments. The multi-spacecraft results are compared with those derived from various single-spacecraft techniques, including minimum-variance analysis of the magnetic field and deHoffmann-Teller, as well as Minimum-Faraday-Residue analysis of plasma velocities and magnetic fields measured during the crossings. In order to improve the overall consistency between multi- and single-spacecraft results, we have also explored the use of hybrid techniques, in which timing information from the four spacecraft is combined with certain limited results from single-spacecraft methods, the remaining results being left for consistency checks. The results show good agreement between magnetopause orientations derived from appropriately chosen single-spacecraft techniques and those obtained from multi-spacecraft timing. The agreement between magnetopause speeds derived from single- and multi-spacecraft methods is quantitatively somewhat less good but it is evident that the speed can change substantially from one crossing to the next within an event. The magnetopause thickness varied substantially from one crossing to the next, within an event. It ranged from 5 to 10 ion gyroradii. The density profile was sharper than the magnetic profile: most of the density change occured in the earthward half of the magnetopause.

Key words. Magnetospheric physics (magnetopause, cusp and

Spacecraft Attitude Determination

DEFF Research Database (Denmark)

Bak, Thomas

This thesis describes the development of an attitude determination system for spacecraft based only on magnetic field measurements. The need for such system is motivated by the increased demands for inexpensive, lightweight solutions for small spacecraft. These spacecraft demands full attitude...... determination based on simple, reliable sensors. Meeting these objectives with a single vector magnetometer is difficult and requires temporal fusion of data in order to avoid local observability problems. In order to guaranteed globally nonsingular solutions, quaternions are generally the preferred attitude...... is a detailed study of the influence of approximations in the modeling of the system. The quantitative effects of errors in the process and noise statistics are discussed in detail. The third contribution is the introduction of these methods to the attitude determination on-board the Ørsted satellite...

Charging in the environment of large spacecraft

International Nuclear Information System (INIS)

Lai, S.T.

1993-01-01

This paper discusses some potential problems of spacecraft charging as a result of interactions between a large spacecraft, such as the Space Station, and its environment. Induced electric field, due to VXB effect, may be important for large spacecraft at low earth orbits. Differential charging, due to different properties of surface materials, may be significant when the spacecraft is partly in sunshine and partly in shadow. Triple-root potential jump condition may occur because of differential charging. Sudden onset of severe differential charging may occur when an electron or ion beam is emitted from the spacecraft. The beam may partially return to the ''hot spots'' on the spacecraft. Wake effects, due to blocking of ambient ion trajectories, may result in an undesirable negative potential region in the vicinity of a large spacecraft. Outgassing and exhaust may form a significant spacecraft induced environment; ionization may occur. Spacecraft charging and discharging may affect the electronic components on board

Results from active spacecraft potential control on the Geotail spacecraft

International Nuclear Information System (INIS)

Schmidt, R.; Arends, H.; Pedersen, A.

1995-01-01

A low and actively controlled electrostatic potential on the outer surfaces of a scientific spacecraft is very important for accurate measurements of cold plasma electrons and ions and the DC to low-frequency electric field. The Japanese/NASA Geotail spacecraft carriers as part of its scientific payload a novel ion emitter for active control of the electrostatic potential on the surface of the spacecraft. The aim of the ion emitter is to reduce the positive surface potential which is normally encountered in the outer magnetosphere when the spacecraft is sunlit. Ion emission clamps the surface potential to near the ambient plasma potential. Without emission control, Geotail has encountered plasma conditions in the lobes of the magnetotail which resulted in surface potentials of up to about +70 V. The ion emitter proves to be able to discharge the outer surfaces of the spacecraft and is capable of keeping the surface potential stable at about +2 V. This potential is measured with respect to one of the electric field probes which are current biased and thus kept at a potential slightly above the ambient plasma potential. The instrument uses the liquid metal field ion emission principle to emit indium ions. The ion beam energy is about 6 keV and the typical total emission current amounts to about 15 μA. Neither variations in the ambient plasma conditions nor operation of two electron emitters on Geotail produce significant variations of the controlled surface potential as long as the resulting electron emission currents remain much smaller than the ion emission current. Typical results of the active potential control are shown, demonstrating the surface potential reduction and its stability over time. 25 refs., 5 figs

Track-etched detectors for the dosimetry of the radiation of cosmic origin

International Nuclear Information System (INIS)

Spurny, F.; Turek, K.

2004-01-01

Cosmic rays contribute to the exposure on the Earth's surface as well as in its surroundings. At the surface and/or at aviation altitudes, there are mostly secondary particles created through the cosmic rays interaction in the atmosphere, which contribute to this type of exposure. Onboard a spacecraft, the exposure comes mostly from primary cosmic rays. Track-etched detectors (TED) are able to characterise both these types of exposure. The contribution of neutrons, of cosmic origin, on the Earth's surface was studied at altitudes from few hundreds to 3000 m using TED in a moderator sphere. The results obtained are compared with other data on this type of natural radiation background. The results of studies performed onboard aircraft and/or spacecraft are presented afterwards. We used TED-based neutron dosemeter, as well as a spectrometer of linear energy transfer based on a chemically etched TED. The results of studies performed onboard aircraft, as well as spacecraft, are presented and discussed, including an attempt to estimate a neutron component onboard the spacecraft. It was found that they correlate with the results of other independent investigations. (authors)

Fractionated Spacecraft Architectures Seeding Study

National Research Council Canada - National Science Library

Mathieu, Charlotte; Weigel, Annalisa

2006-01-01

.... Models were developed from a customer-centric perspective to assess different fractionated spacecraft architectures relative to traditional spacecraft architectures using multi-attribute analysis...

Internet Technology on Spacecraft

Science.gov (United States)

Rash, James; Parise, Ron; Hogie, Keith; Criscuolo, Ed; Langston, Jim; Powers, Edward I. (Technical Monitor)

2000-01-01

The Operating Missions as Nodes on the Internet (OMNI) project has shown that Internet technology works in space missions through a demonstration using the UoSAT-12 spacecraft. An Internet Protocol (IP) stack was installed on the orbiting UoSAT-12 spacecraft and tests were run to demonstrate Internet connectivity and measure performance. This also forms the basis for demonstrating subsequent scenarios. This approach provides capabilities heretofore either too expensive or simply not feasible such as reconfiguration on orbit. The OMNI project recognized the need to reduce the risk perceived by mission managers and did this with a multi-phase strategy. In the initial phase, the concepts were implemented in a prototype system that includes space similar components communicating over the TDRS (space network) and the terrestrial Internet. The demonstration system includes a simulated spacecraft with sample instruments. Over 25 demonstrations have been given to mission and project managers, National Aeronautics and Space Administration (NASA), Department of Defense (DoD), contractor technologists and other decisions makers, This initial phase reached a high point with an OMNI demonstration given from a booth at the Johnson Space Center (JSC) Inspection Day 99 exhibition. The proof to mission managers is provided during this second phase with year 2000 accomplishments: testing the use of Internet technologies onboard an actual spacecraft. This was done with a series of tests performed using the UoSAT-12 spacecraft. This spacecraft was reconfigured on orbit at very low cost. The total period between concept and the first tests was only 6 months! On board software was modified to add an IP stack to support basic IP communications. Also added was support for ping, traceroute and network timing protocol (NTP) tests. These tests show that basic Internet functionality can be used onboard spacecraft. The performance of data was measured to show no degradation from current

Spacecraft momentum control systems

CERN Document Server

Leve, Frederick A; Peck, Mason A

2015-01-01

The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented ...

A simulation of the Four-way lunar Lander-Orbiter tracking mode for the Chang'E-5 mission

Science.gov (United States)

Li, Fei; Ye, Mao; Yan, Jianguo; Hao, Weifeng; Barriot, Jean-Pierre

2016-06-01

The Chang'E-5 mission is the third phase of the Chinese Lunar Exploration Program and will collect and return lunar samples. After sampling, the Orbiter and the ascent vehicle will rendezvous and dock, and both spacecraft will require high precision orbit navigation. In this paper, we present a novel tracking mode-Four-way lunar Lander-Orbiter tracking that possibly can be employed during the Chang'E-5 mission. The mathematical formulas for the Four-way lunar Lander-Orbiter tracking mode are given and implemented in our newly-designed lunar spacecraft orbit determination and gravity field recovery software, the LUnar Gravity REcovery and Analysis Software/System (LUGREAS). The simulated observables permit analysis of the potential contribution Four-way lunar Lander-Orbiter tracking could make to precision orbit determination for the Orbiter. Our results show that the Four-way lunar Lander-Orbiter Range Rate has better geometric constraint on the orbit, and is more sensitive than the traditional two-way range rate that only tracks data between the Earth station and lunar Orbiter. After combining the Four-way lunar Lander-Orbiter Range Rate data with the traditional two-way range rate data and considering the Lander position error and lunar gravity field error, the accuracy of precision orbit determination for the Orbiter in the simulation was improved significantly, with the biggest improvement being one order of magnitude, and the Lander position could be constrained to sub-meter level. This new tracking mode could provide a reference for the Chang'E-5 mission and have enormous potential for the positioning of future lunar farside Lander due to its relay characteristic.

Chemical Pollution from Combustion of Modern Spacecraft Materials

Science.gov (United States)

Mudgett, Paul D.

2013-01-01

Fire is one of the most critical contingencies in spacecraft and any closed environment including submarines. Currently, NASA uses particle based technology to detect fires and hand-held combustion product monitors to track the clean-up and restoration of habitable cabin environment after the fire is extinguished. In the future, chemical detection could augment particle detection to eliminate frequent nuisance false alarms triggered by dust. In the interest of understanding combustion from both particulate and chemical generation, NASA Centers have been collaborating on combustion studies at White Sands Test Facility using modern spacecraft materials as fuels, and both old and new technology to measure the chemical and particulate products of combustion. The tests attempted to study smoldering pyrolysis at relatively low temperatures without ignition to flaming conditions. This paper will summarize the results of two 1-week long tests undertaken in 2012, focusing on the chemical products of combustion. The results confirm the key chemical products are carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen fluoride (HF) and hydrogen chloride (HCl), whose concentrations depend on the particular material and test conditions. For example, modern aerospace wire insulation produces significant concentration of HF, which persists in the test chamber longer than anticipated. These compounds are the analytical targets identified for the development of new tunable diode laser based hand-held monitors, to replace the aging electrochemical sensor based devices currently in use on the International Space Station.

Texture segmentation of non-cooperative spacecrafts images based on wavelet and fractal dimension

Science.gov (United States)

Wu, Kanzhi; Yue, Xiaokui

2011-06-01

With the increase of on-orbit manipulations and space conflictions, missions such as tracking and capturing the target spacecrafts are aroused. Unlike cooperative spacecrafts, fixing beacons or any other marks on the targets is impossible. Due to the unknown shape and geometry features of non-cooperative spacecraft, in order to localize the target and obtain the latitude, we need to segment the target image and recognize the target from the background. The data and errors during the following procedures such as feature extraction and matching can also be reduced. Multi-resolution analysis of wavelet theory reflects human beings' recognition towards images from low resolution to high resolution. In addition, spacecraft is the only man-made object in the image compared to the natural background and the differences will be certainly observed between the fractal dimensions of target and background. Combined wavelet transform and fractal dimension, in this paper, we proposed a new segmentation algorithm for the images which contains complicated background such as the universe and planet surfaces. At first, Daubechies wavelet basis is applied to decompose the image in both x axis and y axis, thus obtain four sub-images. Then, calculate the fractal dimensions in four sub-images using different methods; after analyzed the results of fractal dimensions in sub-images, we choose Differential Box Counting in low resolution image as the principle to segment the texture which has the greatest divergences between different sub-images. This paper also presents the results of experiments by using the algorithm above. It is demonstrated that an accurate texture segmentation result can be obtained using the proposed technique.

Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants

Science.gov (United States)

Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

1998-01-01

Control of air contaminants is a crucial factor in the safety considerations of crewed space flight. Indoor air quality needs to be closely monitored during long range missions such as a Mars mission, and also on large complex space structures such as the International Space Station. This work mainly pertains to the detection and simulation of air contaminants in the space station, though much of the work is easily extended to buildings, and issues of ventilation systems. Here we propose a method with which to track the presence of contaminants using an accurate physical model, and also develop a robust procedure that would raise alarms when certain tolerance levels are exceeded. A part of this research concerns the modeling of air flow inside a spacecraft, and the consequent dispersal pattern of contaminants. Our objective is to also monitor the contaminants on-line, so we develop a state estimation procedure that makes use of the measurements from a sensor system and determines an optimal estimate of the contamination in the system as a function of time and space. The real-time optimal estimates in turn are used to detect faults in the system and also offer diagnoses as to their sources. This work is concerned with the monitoring of air contaminants aboard future generation spacecraft and seeks to satisfy NASA's requirements as outlined in their Strategic Plan document (Technology Development Requirements, 1996).

Cluster PEACE observations of electrons of spacecraft origin

Directory of Open Access Journals (Sweden)

S. Szita

2001-09-01

Full Text Available The two PEACE (Plasma Electron And Current Experiment sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4 solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various environments encountered by the Cluster constellation, including a lunar eclipse interval where the spacecraft potential was reduced but remained positive, and periods of ASPOC (Active Spacecraft POtential Control operation which reduced the spacecraft potential. We demonstrate how the spacecraft potential may be found from a gradient change in the PEACE low energy spectrum, and show how the observed spacecraft electrons are confined by the spacecraft potential. We identify an intense component of the spacecraft electrons with energies equivalent to the spacecraft potential, the arrival direction of which is seen to change when ASPOC is switched on. Another spacecraft electron component, observed in the sunward direction, is reduced in the eclipse but unaffected by ASPOC, and we believe this component is produced in the analyser by solar UV. We find that PEACE anodes with a look direction along the spacecraft surfaces are more susceptible to spacecraft electron contamination than those which look perpendicular to the surface, which justifies the decision to mount PEACE with its field-of-view radially outward rather than tangentially.Key words. Magnetosheric physics (general or miscellaneous Space plasma physics (spacecraft sheaths, wakes, charging

Mechanical Design of Spacecraft

Science.gov (United States)

1962-01-01

In the spring of 1962, engineers from the Engineering Mechanics Division of the Jet Propulsion Laboratory gave a series of lectures on spacecraft design at the Engineering Design seminars conducted at the California Institute of Technology. Several of these lectures were subsequently given at Stanford University as part of the Space Technology seminar series sponsored by the Department of Aeronautics and Astronautics. Presented here are notes taken from these lectures. The lectures were conceived with the intent of providing the audience with a glimpse of the activities of a few mechanical engineers who are involved in designing, building, and testing spacecraft. Engineering courses generally consist of heavily idealized problems in order to allow the more efficient teaching of mathematical technique. Students, therefore, receive a somewhat limited exposure to actual engineering problems, which are typified by more unknowns than equations. For this reason it was considered valuable to demonstrate some of the problems faced by spacecraft designers, the processes used to arrive at solutions, and the interactions between the engineer and the remainder of the organization in which he is constrained to operate. These lecture notes are not so much a compilation of sophisticated techniques of analysis as they are a collection of examples of spacecraft hardware and associated problems. They will be of interest not so much to the experienced spacecraft designer as to those who wonder what part the mechanical engineer plays in an effort such as the exploration of space.

Pose Self-Measurement of Noncooperative Spacecraft Based on Solar Panel Triangle Structure

Directory of Open Access Journals (Sweden)

Jingzhou Song

2015-01-01

Full Text Available Aiming at the recognition and location of noncooperative spacecraft, this paper presents a monocular vision pose measurement method based on solar triangle structure. First of all, an autonomous recognition algorithm of feature structure based on sliding window Hough transformation (SWHT and inscribed circle of a triangle is proposed, and the image coordinates of feature points on the triangle can be obtained relying on this algorithm, combined with the P4P algorithm and the structure of spacecraft, calculating the relative pose of target expressed by rotation and translation matrix. The whole algorithm can be loaded into the prewritten onboard program, which will get the autocomplete feature structure extraction and relative pose measurement without human intervention, and this method does not need to mount any markers on the target. Then compare the measured values with the accurate value of the laser tracker, so that a conclusion can be drawn that the maximum position error is lower than 5% and the rotation error is lower than 4%, which meets the requirements of noncooperative spacecraft’s pose measurement for observations, tracking, and docking in the final rendezvous phase.

Small Orbital Stereo Tracking Camera Technology Development

Science.gov (United States)

Gagliano, L.; Bryan, T.; MacLeod, T.

On-Orbit Small Debris Tracking and Characterization is a technical gap in the current National Space Situational Awareness necessary to safeguard orbital assets and crew. This poses a major risk of MOD damage to ISS and Exploration vehicles. In 2015 this technology was added to NASAs Office of Chief Technologist roadmap. For missions flying in or assembled in or staging from LEO, the physical threat to vehicle and crew is needed in order to properly design the proper level of MOD impact shielding and proper mission design restrictions. Need to verify debris flux and size population versus ground RADAR tracking. Use of ISS for In-Situ Orbital Debris Tracking development provides attitude, power, data and orbital access without a dedicated spacecraft or restricted operations on-board a host vehicle as a secondary payload. Sensor Applicable to in-situ measuring orbital debris in flux and population in other orbits or on other vehicles. Could enhance safety on and around ISS. Some technologies extensible to monitoring of extraterrestrial debris as well To help accomplish this, new technologies must be developed quickly. The Small Orbital Stereo Tracking Camera is one such up and coming technology. It consists of flying a pair of intensified megapixel telephoto cameras to evaluate Orbital Debris (OD) monitoring in proximity of International Space Station. It will demonstrate on-orbit optical tracking (in situ) of various sized objects versus ground RADAR tracking and small OD models. The cameras are based on Flight Proven Advanced Video Guidance Sensor pixel to spot algorithms (Orbital Express) and military targeting cameras. And by using twin cameras we can provide Stereo images for ranging & mission redundancy. When pointed into the orbital velocity vector (RAM), objects approaching or near the stereo camera set can be differentiated from the stars moving upward in background.

CONTRIBUTION OF DIFFERENT PARTICLES MEASURED WITH TRACK ETCHED DETECTORS ONBOARD ISS.

Science.gov (United States)

Ambrožová, I; Davídková, M; Brabcová, K Pachnerová; Tolochek, R V; Shurshakov, V A

2017-09-29

Cosmic radiation consists of primary high-energy galactic and solar particles. When passing through spacecraft walls and astronauts' bodies, the spectrum becomes even more complex due to generating of secondary particles through fragmentation and nuclear interactions. Total radiation exposure is contributed by both these components. With an advantage, space research uses track etched detectors from the group of passive detectors visualizing the tracks of particles, in this case by etching. The detectors can discriminate between various components of cosmic radiation. A method is introduced for the separation of the different types of particles according to their range using track etched detectors. The method is demonstrated using detectors placed in Russian segment of the International Space Station in 2009. It is shown that the primary high-energy heavy ions with long range contribute up to 56% of the absorbed dose and up to 50% to the dose equivalent. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Determination of the System Mass and the Individual Masses of Pluto and Charon from New Horizons Radio Tracking

Science.gov (United States)

Hahn, M.; Paetzold, M.; Andert, T.; Bird, M. K.; Tyler, G. L.; Hinson, D. P.; Linscott, I.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Olkin, C.

2016-12-01

One objective of the New Horizons Radio Science Experiment REX is the direct determination of the system mass and the individual masses of Pluto and Charon. About four weeks of two-way radio tracking centered around the closest approach of New Horizons to the Pluto system were processed. Major problems during the processing were the changes in spacecraft attitude by thrusters which applied extra Δv to the spacecraft motion masking partially the continuously perturbed motion caused by the attracting forces of the Pluto system members. The times of the spacecraft thruster activity are known but the applied Δv magnitude needed to be specifically adjusted. No two-way tracking was available during the flyby day on 14th July but slots of the REX one-way uplink observations cover the most important time near closest approach, these are for example the Pluto and Charon Earth occultation entries and exits. The REX data during the flyby day allowed to extract the individual masses of Pluto and Charon from the system mass at high precision. The relative errors of the mass determinations are below 0.02% and 0.2%, respectively. The masses of the 4 small satellites in the Pluto system could not be resolved.

Deployable Brake for Spacecraft

Science.gov (United States)

Rausch, J. R.; Maloney, J. W.

1987-01-01

Aerodynamic shield that could be opened and closed proposed. Report presents concepts for deployable aerodynamic brake. Brake used by spacecraft returning from high orbit to low orbit around Earth. Spacecraft makes grazing passes through atmosphere to slow down by drag of brake. Brake flexible shield made of woven metal or ceramic withstanding high temperatures created by air friction. Stored until needed, then deployed by set of struts.

Ulysses spacecraft control and monitoring system

Science.gov (United States)

Hamer, P. A.; Snowden, P. J.

1991-01-01

The baseline Ulysses spacecraft control and monitoring system (SCMS) concepts and the converted SCMS, residing on a DEC/VAX 8350 hardware, are considered. The main functions of the system include monitoring and displaying spacecraft telemetry, preparing spacecraft commands, producing hard copies of experimental data, and archiving spacecraft telemetry. The SCMS system comprises over 20 subsystems ranging from low-level utility routines to the major monitoring and control software. These in total consist of approximately 55,000 lines of FORTRAN source code and 100 VMS command files. The SCMS major software facilities are described, including database files, telemetry processing, telecommanding, archiving of data, and display of telemetry.

Contemporary state of spacecraft/environment interaction research

CERN Document Server

Novikov, L S

1999-01-01

Various space environment effects on spacecraft materials and equipment, and the reverse effects of spacecrafts and rockets on space environment are considered. The necessity of permanent updating and perfection of our knowledge on spacecraft/environment interaction processes is noted. Requirements imposed on models of space environment in theoretical and experimental researches of various aspects of the spacecraft/environment interaction problem are formulated. In this field, main problems which need to be solved today and in the nearest future are specified. The conclusion is made that the joint analysis of both aspects of spacecraft/environment interaction problem promotes the most effective solution of the problem.

Spacecraft Jitter Attenuation Using Embedded Piezoelectric Actuators

Science.gov (United States)

Belvin, W. Keith

1995-01-01

Remote sensing from spacecraft requires precise pointing of measurement devices in order to achieve adequate spatial resolution. Unfortunately, various spacecraft disturbances induce vibrational jitter in the remote sensing instruments. The NASA Langley Research Center has performed analysis, simulations, and ground tests to identify the more promising technologies for minimizing spacecraft pointing jitter. These studies have shown that the use of smart materials to reduce spacecraft jitter is an excellent match between a maturing technology and an operational need. This paper describes the use of embedding piezoelectric actuators for vibration control and payload isolation. In addition, recent advances in modeling, simulation, and testing of spacecraft pointing jitter are discussed.

Gravity Probe B spacecraft description

International Nuclear Information System (INIS)

Bennett, Norman R; Burns, Kevin; Katz, Russell; Kirschenbaum, Jon; Mason, Gary; Shehata, Shawky

2015-01-01

The Gravity Probe B spacecraft, developed, integrated, and tested by Lockheed Missiles and Space Company and later Lockheed Martin Corporation, consisted of structures, mechanisms, command and data handling, attitude and translation control, electrical power, thermal control, flight software, and communications. When integrated with the payload elements, the integrated system became the space vehicle. Key requirements shaping the design of the spacecraft were: (1) the tight mission timeline (17 months, 9 days of on-orbit operation), (2) precise attitude and translational control, (3) thermal protection of science hardware, (4) minimizing aerodynamic, magnetic, and eddy current effects, and (5) the need to provide a robust, low risk spacecraft. The spacecraft met all mission requirements, as demonstrated by dewar lifetime meeting specification, positive power and thermal margins, precision attitude control and drag-free performance, reliable communications, and the collection of more than 97% of the available science data. (paper)

Estimating Torque Imparted on Spacecraft Using Telemetry

Science.gov (United States)

Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

2013-01-01

There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

Attitude coordination for spacecraft formation with multiple communication delays

Directory of Open Access Journals (Sweden)

Guo Yaohua

2015-04-01

Full Text Available Communication delays are inherently present in information exchange between spacecraft and have an effect on the control performance of spacecraft formation. In this work, attitude coordination control of spacecraft formation is addressed, which is in the presence of multiple communication delays between spacecraft. Virtual system-based approach is utilized in case that a constant reference attitude is available to only a part of the spacecraft. The feedback from the virtual systems to the spacecraft formation is introduced to maintain the formation. Using backstepping control method, input torque of each spacecraft is designed such that the attitude of each spacecraft converges asymptotically to the states of its corresponding virtual system. Furthermore, the backstepping technique and the Lyapunov–Krasovskii method contribute to the control law design when the reference attitude is time-varying and can be obtained by each spacecraft. Finally, effectiveness of the proposed methodology is illustrated by the numerical simulations of a spacecraft formation.

Large-Scale Spacecraft Fire Safety Tests

Science.gov (United States)

Urban, David; Ruff, Gary A.; Ferkul, Paul V.; Olson, Sandra; Fernandez-Pello, A. Carlos; T'ien, James S.; Torero, Jose L.; Cowlard, Adam J.; Rouvreau, Sebastien; Minster, Olivier;

SHARP - Automated monitoring of spacecraft health and status

Science.gov (United States)

Atkinson, David J.; James, Mark L.; Martin, R. G.

1990-01-01

Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

SHARP: Automated monitoring of spacecraft health and status

Science.gov (United States)

Atkinson, David J.; James, Mark L.; Martin, R. Gaius

1991-01-01

Briefly discussed here are the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory (JPL). Some of the difficulties associated with the existing technology used in mission operations are highlighted. A new automated system based on artificial intelligence technology is described which seeks to overcome many of these limitations. The system, called the Spacecraft Health Automated Reasoning Prototype (SHARP), is designed to automate health and status analysis for multi-mission spacecraft and ground data systems operations. The system has proved to be effective for detecting and analyzing potential spacecraft and ground systems problems by performing real-time analysis of spacecraft and ground data systems engineering telemetry. Telecommunications link analysis of the Voyager 2 spacecraft was the initial focus for evaluation of the system in real-time operations during the Voyager spacecraft encounter with Neptune in August 1989.

Dual Use of Image Based Tracking Techniques: Laser Eye Surgery and Low Vision Prosthesis

Science.gov (United States)

Juday, Richard D.; Barton, R. Shane

1994-01-01

With a concentration on Fourier optics pattern recognition, we have developed several methods of tracking objects in dynamic imagery to automate certain space applications such as orbital rendezvous and spacecraft capture, or planetary landing. We are developing two of these techniques for Earth applications in real-time medical image processing. The first is warping of a video image, developed to evoke shift invariance to scale and rotation in correlation pattern recognition. The technology is being applied to compensation for certain field defects in low vision humans. The second is using the optical joint Fourier transform to track the translation of unmodeled scenes. Developed as an image fixation tool to assist in calculating shape from motion, it is being applied to tracking motions of the eyeball quickly enough to keep a laser photocoagulation spot fixed on the retina, thus avoiding collateral damage.

Spacecraft Charging: Hazard Causes, Hazard Effects, Hazard Controls

Science.gov (United States)

Koontz, Steve.

2018-01-01

Spacecraft flight environments are characterized both by a wide range of space plasma conditions and by ionizing radiation (IR), solar ultraviolet and X-rays, magnetic fields, micrometeoroids, orbital debris, and other environmental factors, all of which can affect spacecraft performance. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of spacecraft charging and charging effects that can be applied to solving practical spacecraft and spacesuit engineering design, verification, and operations problems, with an emphasis on spacecraft operations in low-Earth orbit, Earth's magnetosphere, and cis-Lunar space.

A localized swarm of low-resource CubeSat-class spacecraft for auroral ionospheric science

Science.gov (United States)

Clayton, R.; Lynch, K. A.; Gayetsky, L.; Guinther, J.; Slagle, A.; Currey, S.

2012-12-01

In interesting and dynamic auroral ionospheric plasmas, single-point in situ measurements are insufficient. Changes in measurements recorded from a single probe can be ascribed to either changes in position or to changes over time, and gradient scales can only be inferred. A localized array of sensors deployed as a low-resource swarm from a main deployer, can address these issues. We consider two aspects of designing such a swarm: (a) maintaining the localization in a low-cost manner, and (b) creating an extremely low-resource spacecraft by taking advantage of commercially available technologies. For a few-week low-altitude mission, STK (SatelliteToolKit) studies show that with proper deployment, an array of CubeSat-class spacecraft near 350 km altitude can regroup once per orbit to within a few 10s of km. Kepler's laws and Hill's equations allow us to put constraints on the capability of the deployer needed, in order to deploy the array with a minimal component of the ejection velocity along the orbital track. In order to keep the cost of each spacecraft low, we are exploring commercially available technologies such as Arduino controllers and video-game sensors. The Arduino on each payload will take in information from the sensors on the payload, and will send the information to a DNT-900MHz local area communications system. We show an example experiment measuring river flows on the Connecticut river, and discuss the design of our payload swarm.

Automating Trend Analysis for Spacecraft Constellations

Science.gov (United States)

Davis, George; Cooter, Miranda; Updike, Clark; Carey, Everett; Mackey, Jennifer; Rykowski, Timothy; Powers, Edward I. (Technical Monitor)

2001-01-01

Spacecraft trend analysis is a vital mission operations function performed by satellite controllers and engineers, who perform detailed analyses of engineering telemetry data to diagnose subsystem faults and to detect trends that may potentially lead to degraded subsystem performance or failure in the future. It is this latter function that is of greatest importance, for careful trending can often predict or detect events that may lead to a spacecraft's entry into safe-hold. Early prediction and detection of such events could result in the avoidance of, or rapid return to service from, spacecraft safing, which not only results in reduced recovery costs but also in a higher overall level of service for the satellite system. Contemporary spacecraft trending activities are manually intensive and are primarily performed diagnostically after a fault occurs, rather than proactively to predict its occurrence. They also tend to rely on information systems and software that are oudated when compared to current technologies. When coupled with the fact that flight operations teams often have limited resources, proactive trending opportunities are limited, and detailed trend analysis is often reserved for critical responses to safe holds or other on-orbit events such as maneuvers. While the contemporary trend analysis approach has sufficed for current single-spacecraft operations, it will be unfeasible for NASA's planned and proposed space science constellations. Missions such as the Dynamics, Reconnection and Configuration Observatory (DRACO), for example, are planning to launch as many as 100 'nanospacecraft' to form a homogenous constellation. A simple extrapolation of resources and manpower based on single-spacecraft operations suggests that trending for such a large spacecraft fleet will be unmanageable, unwieldy, and cost-prohibitive. It is therefore imperative that an approach to automating the spacecraft trend analysis function be studied, developed, and applied to

Radiation Effects on Spacecraft Structural Materials

International Nuclear Information System (INIS)

Wang, Jy-An J.; Ellis, Ronald J.; Hunter, Hamilton T.; Singleterry, Robert C. Jr.

2002-01-01

Research is being conducted to develop an integrated technology for the prediction of aging behavior for space structural materials during service. This research will utilize state-of-the-art radiation experimental apparatus and analysis, updated codes and databases, and integrated mechanical and radiation testing techniques to investigate the suitability of numerous current and potential spacecraft structural materials. Also included are the effects on structural materials in surface modules and planetary landing craft, with or without fission power supplies. Spacecraft structural materials would also be in hostile radiation environments on the surface of the moon and planets without appreciable atmospheres and moons around planets with large intense magnetic and radiation fields (such as the Jovian moons). The effects of extreme temperature cycles in such locations compounds the effects of radiation on structural materials. This paper describes the integrated methodology in detail and shows that it will provide a significant technological advance for designing advanced spacecraft. This methodology will also allow for the development of advanced spacecraft materials through the understanding of the underlying mechanisms of material degradation in the space radiation environment. Thus, this technology holds a promise for revolutionary advances in material damage prediction and protection of space structural components as, for example, in the development of guidelines for managing surveillance programs regarding the integrity of spacecraft components, and the safety of the aging spacecraft. (authors)

Prospects for Measuring Planetary Spin and Frame-Dragging in Spacecraft Timing Signals

Energy Technology Data Exchange (ETDEWEB)

Schärer, Andreas; Bondarescu, Ruxandra [Department of Physics, University of Zurich, Zurich (Switzerland); Saha, Prasenjit [Department of Physics, University of Zurich, Zurich (Switzerland); Institute for Computational Science, University of Zurich, Zurich (Switzerland); Angélil, Raymond [Institute for Computational Science, University of Zurich, Zurich (Switzerland); Helled, Ravit [Institute for Computational Science, University of Zurich, Zurich (Switzerland); Department of Geosciences, Tel Aviv University, Tel Aviv (Israel); Jetzer, Philippe, E-mail: andreas.schaerer@physik.uzh.ch [Department of Physics, University of Zurich, Zurich (Switzerland)

2017-09-05

Satellite tracking involves sending electromagnetic signals to Earth. Both the orbit of the spacecraft and the electromagnetic signals themselves are affected by the curvature of spacetime. The arrival time of the pulses is compared to the ticks of local clocks to reconstruct the orbital path of the satellite to high accuracy, and implicitly measure general relativistic effects. In particular, Schwarzschild space curvature (static) and frame-dragging (stationary) due to the planet's spin affect the satellite's orbit. The dominant relativistic effect on the path of the signal photons is Shapiro delays due to static space curvature. We compute these effects for some current and proposed space missions, using a Hamiltonian formulation in four dimensions. For highly eccentric orbits, such as in the Juno mission and in the Cassini Grand Finale, the relativistic effects have a kick-like nature, which could be advantageous for detecting them if their signatures are properly modeled as functions of time. Frame-dragging appears, in principle, measurable by Juno and Cassini, though not by Galileo 5 and 6. Practical measurement would require disentangling frame-dragging from the Newtonian “foreground” such as the gravitational quadrupole which has an impact on both the spacecraft's orbit and the signal propagation. The foreground problem remains to be solved.

Vibration and Acoustic Testing for Mars Micromission Spacecraft

Science.gov (United States)

Kern, Dennis L.; Scharton, Terry D.

1999-01-01

The objective of the Mars Micromission program being managed by the Jet Propulsion Laboratory (JPL) for NASA is to develop a common spacecraft that can carry telecommunications equipment and a variety of science payloads for exploration of Mars. The spacecraft will be capable of carrying robot landers and rovers, cameras, probes, balloons, gliders or aircraft, and telecommunications equipment to Mars at much lower cost than recent NASA Mars missions. The lightweight spacecraft (about 220 Kg mass) will be launched in a cooperative venture with CNES as a TWIN auxiliary payload on the Ariane 5 launch vehicle. Two or more Mars Micromission launches are planned for each Mars launch opportunity, which occur every 26 months. The Mars launch window for the first mission is November 1, 2002 through April 2003, which is planned to be a Mars airplane technology demonstration mission to coincide with the 100 year anniversary of the Kittyhawk flight. Several subsequent launches will create a telecommunications network orbiting Mars, which will provide for continuous communication with lenders and rovers on the Martian surface. Dedicated science payload flights to Mars are slated to start in 2005. This new cheaper and faster approach to Mars exploration calls for innovative approaches to the qualification of the Mars Micromission spacecraft for the Ariane 5 launch vibration and acoustic environments. JPL has in recent years implemented new approaches to spacecraft testing that may be effectively applied to the Mars Micromission. These include 1) force limited vibration testing, 2) combined loads, vibration and modal testing, and 3) direct acoustic testing. JPL has performed nearly 200 force limited vibration tests in the past 9 years; several of the tests were on spacecraft and large instruments, including the Cassini and Deep Space One spacecraft. Force limiting, which measures and limits the spacecraft base reaction force using triaxial force gages sandwiched between the

Foot Pedals for Spacecraft Manual Control

Science.gov (United States)

Love, Stanley G.; Morin, Lee M.; McCabe, Mary

2010-01-01

Fifty years ago, NASA decided that the cockpit controls in spacecraft should be like the ones in airplanes. But controls based on the stick and rudder may not be best way to manually control a vehicle in space. A different method is based on submersible vehicles controlled with foot pedals. A new pilot can learn the sub's control scheme in minutes and drive it hands-free. We are building a pair of foot pedals for spacecraft control, and will test them in a spacecraft flight simulator.

Spacecraft Thermal Management

Science.gov (United States)

Hurlbert, Kathryn Miller

2009-01-01

In the 21st century, the National Aeronautics and Space Administration (NASA), the Russian Federal Space Agency, the National Space Agency of Ukraine, the China National Space Administration, and many other organizations representing spacefaring nations shall continue or newly implement robust space programs. Additionally, business corporations are pursuing commercialization of space for enabling space tourism and capital business ventures. Future space missions are likely to include orbiting satellites, orbiting platforms, space stations, interplanetary vehicles, planetary surface missions, and planetary research probes. Many of these missions will include humans to conduct research for scientific and terrestrial benefits and for space tourism, and this century will therefore establish a permanent human presence beyond Earth s confines. Other missions will not include humans, but will be autonomous (e.g., satellites, robotic exploration), and will also serve to support the goals of exploring space and providing benefits to Earth s populace. This section focuses on thermal management systems for human space exploration, although the guiding principles can be applied to unmanned space vehicles as well. All spacecraft require a thermal management system to maintain a tolerable thermal environment for the spacecraft crew and/or equipment. The requirements for human rating and the specified controlled temperature range (approximately 275 K - 310 K) for crewed spacecraft are unique, and key design criteria stem from overall vehicle and operational/programatic considerations. These criteria include high reliability, low mass, minimal power requirements, low development and operational costs, and high confidence for mission success and safety. This section describes the four major subsystems for crewed spacecraft thermal management systems, and design considerations for each. Additionally, some examples of specialized or advanced thermal system technologies are presented

Cellular track model of biological damage to mammalian cell cultures from galactic cosmic rays

International Nuclear Information System (INIS)

Cucinotta, F.A.; Katz, R.; Wilson, J.W.; Townsend, L.W.; Nealy, J.E.; Shinn, J.L.

1991-02-01

The assessment of biological damage from the galactic cosmic rays (GCR) is a current interest for exploratory class space missions where the highly ionizing, high-energy, high-charge ions (HZE) particles are the major concern. The relative biological effectiveness (RBE) values determined by ground-based experiments with HZE particles are well described by a parametric track theory of cell inactivation. Using the track model and a deterministic GCR transport code, the biological damage to mammalian cell cultures is considered for 1 year in free space at solar minimum for typical spacecraft shielding. Included are the effects of projectile and target fragmentation. The RBE values for the GCR spectrum which are fluence-dependent in the track model are found to be more severe than the quality factors identified by the International Commission on Radiological Protection publication 26 and seem to obey a simple scaling law with the duration period in free space

Cellular track model of biological damage to mammalian cell cultures from galactic cosmic rays

Science.gov (United States)

Cucinotta, Francis A.; Katz, Robert; Wilson, John W.; Townsend, Lawrence W.; Nealy, John E.; Shinn, Judy L.

1991-01-01

The assessment of biological damage from the galactic cosmic rays (GCR) is a current interest for exploratory class space missions where the highly ionizing, high-energy, high-charge ions (HZE) particles are the major concern. The relative biological effectiveness (RBE) values determined by ground-based experiments with HZE particles are well described by a parametric track theory of cell inactivation. Using the track model and a deterministic GCR transport code, the biological damage to mammalian cell cultures is considered for 1 year in free space at solar minimum for typical spacecraft shielding. Included are the effects of projectile and target fragmentation. The RBE values for the GCR spectrum which are fluence-dependent in the track model are found to be more severe than the quality factors identified by the International Commission on Radiological Protection publication 26 and seem to obey a simple scaling law with the duration period in free space.

On the spacecraft attitude stabilization in the orbital frame

Directory of Open Access Journals (Sweden)

Antipov Kirill A.

2012-01-01

Full Text Available The paper deals with spacecraft in the circular near-Earth orbit. The spacecraft interacts with geomagnetic field by the moments of Lorentz and magnetic forces. The octupole approximation of the Earth’s magnetic field is accepted. The spacecraft electromagnetic parameters, namely the electrostatic charge moment of the first order and the eigen magnetic moment are the controlled quasiperiodic functions. The control algorithms for the spacecraft electromagnetic parameters, which allows to stabilize the spacecraft attitude position in the orbital frame are obtained. The stability of the spacecraft stabilized orientation is proved both analytically and by PC computations.

False star detection and isolation during star tracking based on improved chi-square tests.

Science.gov (United States)

Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Yang, Yanqiang; Su, Guohua

2017-08-01

The star sensor is a precise attitude measurement device for a spacecraft. Star tracking is the main and key working mode for a star sensor. However, during star tracking, false stars become an inevitable interference for star sensor applications, which may result in declined measurement accuracy. A false star detection and isolation algorithm in star tracking based on improved chi-square tests is proposed in this paper. Two estimations are established based on a Kalman filter and a priori information, respectively. The false star detection is operated through adopting the global state chi-square test in a Kalman filter. The false star isolation is achieved using a local state chi-square test. Semi-physical experiments under different trajectories with various false stars are designed for verification. Experiment results show that various false stars can be detected and isolated from navigation stars during star tracking, and the attitude measurement accuracy is hardly influenced by false stars. The proposed algorithm is proved to have an excellent performance in terms of speed, stability, and robustness.

Standardizing the information architecture for spacecraft operations

Science.gov (United States)

Easton, C. R.

1994-01-01

This paper presents an information architecture developed for the Space Station Freedom as a model from which to derive an information architecture standard for advanced spacecraft. The information architecture provides a way of making information available across a program, and among programs, assuming that the information will be in a variety of local formats, structures and representations. It provides a format that can be expanded to define all of the physical and logical elements that make up a program, add definitions as required, and import definitions from prior programs to a new program. It allows a spacecraft and its control center to work in different representations and formats, with the potential for supporting existing spacecraft from new control centers. It supports a common view of data and control of all spacecraft, regardless of their own internal view of their data and control characteristics, and of their communications standards, protocols and formats. This information architecture is central to standardizing spacecraft operations, in that it provides a basis for information transfer and translation, such that diverse spacecraft can be monitored and controlled in a common way.

Probing the earth's gravity field using Satellite-to-Satellite Tracking (SST)

Science.gov (United States)

Vonbun, F. O.

1976-01-01

Satellite-to-Satellite (SST) tests, namely: (a) the ATS-6/GEOS-3 and (b) the ATS-6/Apollo-Soyuz experiment and some of the results obtained are described. The main purpose of these two experiments was first to track via ATS-6 the GEOS-3 as well as the Apollo-Soyuz and to use these tracking data to determine (a) both orbits, that is, ATS-6, GEOS-3 and/or the Apollo-Soyuz orbits at the same time; (b) each of these orbits alone; and (c) test the ATS-6/GEOS-3 and/or Apollo-Soyuz SST link to study local gravity anomalies; and, second, to test communications, command, and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground. The Apollo-Soyuz Geodynamics Experiment is discussed in some detail.

Nonlinear Slewing Spacecraft Control Based on Exergy, Power Flow, and Static and Dynamic Stability

Science.gov (United States)

Robinett, Rush D.; Wilson, David G.

2009-10-01

This paper presents a new nonlinear control methodology for slewing spacecraft, which provides both necessary and sufficient conditions for stability by identifying the stability boundaries, rigid body modes, and limit cycles. Conservative Hamiltonian system concepts, which are equivalent to static stability of airplanes, are used to find and deal with the static stability boundaries: rigid body modes. The application of exergy and entropy thermodynamic concepts to the work-rate principle provides a natural partitioning through the second law of thermodynamics of power flows into exergy generator, dissipator, and storage for Hamiltonian systems that is employed to find the dynamic stability boundaries: limit cycles. This partitioning process enables the control system designer to directly evaluate and enhance the stability and performance of the system by balancing the power flowing into versus the power dissipated within the system subject to the Hamiltonian surface (power storage). Relationships are developed between exergy, power flow, static and dynamic stability, and Lyapunov analysis. The methodology is demonstrated with two illustrative examples: (1) a nonlinear oscillator with sinusoidal damping and (2) a multi-input-multi-output three-axis slewing spacecraft that employs proportional-integral-derivative tracking control with numerical simulation results.

Guidance and control of swarms of spacecraft

Science.gov (United States)

Morgan, Daniel James

There has been considerable interest in formation flying spacecraft due to their potential to perform certain tasks at a cheaper cost than monolithic spacecraft. Formation flying enables the use of smaller, cheaper spacecraft that distribute the risk of the mission. Recently, the ideas of formation flying have been extended to spacecraft swarms made up of hundreds to thousands of 100-gram-class spacecraft known as femtosatellites. The large number of spacecraft and limited capabilities of each individual spacecraft present a significant challenge in guidance, navigation, and control. This dissertation deals with the guidance and control algorithms required to enable the flight of spacecraft swarms. The algorithms developed in this dissertation are focused on achieving two main goals: swarm keeping and swarm reconfiguration. The objectives of swarm keeping are to maintain bounded relative distances between spacecraft, prevent collisions between spacecraft, and minimize the propellant used by each spacecraft. Swarm reconfiguration requires the transfer of the swarm to a specific shape. Like with swarm keeping, minimizing the propellant used and preventing collisions are the main objectives. Additionally, the algorithms required for swarm keeping and swarm reconfiguration should be decentralized with respect to communication and computation so that they can be implemented on femtosats, which have limited hardware capabilities. The algorithms developed in this dissertation are concerned with swarms located in low Earth orbit. In these orbits, Earth oblateness and atmospheric drag have a significant effect on the relative motion of the swarm. The complicated dynamic environment of low Earth orbits further complicates the swarm-keeping and swarm-reconfiguration problems. To better develop and test these algorithms, a nonlinear, relative dynamic model with J2 and drag perturbations is developed. This model is used throughout this dissertation to validate the algorithms

Passive Plasma Contact Mechanisms for Small-Scale Spacecraft

Science.gov (United States)

McTernan, Jesse K.

Small-scale spacecraft represent a paradigm shift in how entities such as academia, industry, engineering firms, and the scientific community operate in space. However, although the paradigm shift produces unique opportunities to build satellites in unique ways for novel missions, there are also significant challenges that must be addressed. This research addresses two of the challenges associated with small-scale spacecraft: 1) the miniaturization of spacecraft and associated instrumentation and 2) the need to transport charge across the spacecraft-environment boundary. As spacecraft decrease in size, constraints on the size, weight, and power of on-board instrumentation increase--potentially limiting the instrument's functionality or ability to integrate with the spacecraft. These constraints drive research into mechanisms or techniques that use little or no power and efficiently utilize existing resources. One limited resource on small-scale spacecraft is outer surface area, which is often covered with solar panels to meet tight power budgets. This same surface area could also be needed for passive neutralization of spacecraft charging. This research explores the use of a transparent, conductive layer on the solar cell coverglass that is electrically connected to spacecraft ground potential. This dual-purpose material facilitates the use of outer surfaces for both energy harvesting of solar photons as well as passive ion collection. Mission capabilities such as in-situ plasma measurements that were previously infeasible on small-scale platforms become feasible with the use of indium tin oxide-coated solar panel coverglass. We developed test facilities that simulate the space environment in low Earth orbit to test the dual-purpose material and the various application of this approach. Particularly, this research is in support of two upcoming missions: OSIRIS-3U, by Penn State's Student Space Programs Lab, and MiTEE, by the University of Michigan. The purpose of

A Comprehensive Characterization of Microorganisms and Allergens in Spacecraft Environment

Science.gov (United States)

Castro, V.A.; Ott, C.M.; Garcia, V.M.; John, J.; Buttner, M.P.; Cruz, P.; Pierson, D.L.

2009-01-01

The determination of risk from infectious disease during long-duration missions is composed of several factors including the concentration and the characteristics of the infectious agent. Thus, a thorough knowledge of the microorganisms aboard spacecraft is essential in mitigating infectious disease risk to the crew. While stringent steps are taken to minimize the transfer of potential pathogens to spacecraft, several medically significant organisms have been isolated from both the Mir and International Space Station (ISS). Historically, the method for isolation and identification of microorganisms from spacecraft environmental samples depended upon their growth on culture media. Unfortunately, only a fraction of the organisms may grow on a culture medium, potentially omitting those microorganisms whose nutritional and physical requirements for growth are not met. Thus, several pathogens may not have been detected, such as Legionella pneumophila, the etiological agent of Legionnaire s disease. We hypothesize that environmental analysis using non-culture-based technologies will reveal microorganisms, allergens, and microbial toxins not previously reported in spacecraft, allowing for a more complete health assessment. The development of techniques for this flight experiment, operationally named SWAB, has already provided advances in NASA laboratory processes and beneficial information toward human health risk assessment. The translation of 16S ribosomal DNA sequencing for the identification of bacteria from the SWAB experiment to nominal operations has increased bacterial speciation of environmental isolates from previous flights three fold compared to previous conventional methodology. The incorporation of molecular-based DNA fingerprinting using repetitive sequence-based polymerase chain reaction (rep-PCR) into the capabilities of the laboratory has provided a methodology to track microorganisms between crewmembers and their environment. Both 16S ribosomal DNA

Spacecraft command and control using expert systems

Science.gov (United States)

Norcross, Scott; Grieser, William H.

1994-01-01

This paper describes a product called the Intelligent Mission Toolkit (IMT), which was created to meet the changing demands of the spacecraft command and control market. IMT is a command and control system built upon an expert system. Its primary functions are to send commands to the spacecraft and process telemetry data received from the spacecraft. It also controls the ground equipment used to support the system, such as encryption gear, and telemetry front-end equipment. Add-on modules allow IMT to control antennas and antenna interface equipment. The design philosophy for IMT is to utilize available commercial products wherever possible. IMT utilizes Gensym's G2 Real-time Expert System as the core of the system. G2 is responsible for overall system control, spacecraft commanding control, and spacecraft telemetry analysis and display. Other commercial products incorporated into IMT include the SYBASE relational database management system and Loral Test and Integration Systems' System 500 for telemetry front-end processing.

Artist concept of Galileo spacecraft

Science.gov (United States)

1988-01-01

Galileo spacecraft is illustrated in artist concept. Gallileo, named for the Italian astronomer, physicist and mathematician who is credited with construction of the first complete, practical telescope in 1620, will make detailed studies of Jupiter. A cooperative program with the Federal Republic of Germany the Galileo mission will amplify information acquired by two Voyager spacecraft in their brief flybys. Galileo is a two-element system that includes a Jupiter-orbiting observatory and an entry probe. Jet Propulsion Laboratory (JPL) is Galileo project manager and builder of the main spacecraft. Ames Research Center (ARC) has responsibility for the entry probe, which was built by Hughes Aircraft Company and General Electric. Galileo will be deployed from the payload bay (PLB) of Atlantis, Orbiter Vehicle (OV) 104, during mission STS-34.

Addressing EO-1 Spacecraft Pulsed Plasma Thruster EMI Concerns

Science.gov (United States)

Zakrzwski, C. M.; Davis, Mitch; Sarmiento, Charles; Bauer, Frank H. (Technical Monitor)

2001-01-01

The Pulsed Plasma Thruster (PPT) Experiment on the Earth Observing One (EO-1) spacecraft has been designed to demonstrate the capability of a new generation PPT to perform spacecraft attitude control. Results from PPT unit level radiated electromagnetic interference (EMI) tests led to concerns about potential interference problems with other spacecraft subsystems. Initial plans to address these concerns included firing the PPT at the spacecraft level both in atmosphere, with special ground support equipment. and in vacuum. During the spacecraft level tests, additional concerns where raised about potential harm to the Advanced Land Imager (ALI). The inadequacy of standard radiated emission test protocol to address pulsed electromagnetic discharges and the lack of resources required to perform compatibility tests between the PPT and an ALI test unit led to changes in the spacecraft level validation plan. An EMI shield box for the PPT was constructed and validated for spacecraft level ambient testing. Spacecraft level vacuum tests of the PPT were deleted. Implementation of the shield box allowed for successful spacecraft level testing of the PPT while eliminating any risk to the ALI. The ALI demonstration will precede the PPT demonstration to eliminate any possible risk of damage of ALI from PPT operation.

How Spacecraft Fly Spaceflight Without Formulae

CERN Document Server

Swinerd, Graham

2009-01-01

About half a century ago a small satellite, Sputnik 1, was launched. The satellite did very little other than to transmit a radio signal to announce its presence in orbit. However, this humble beginning heralded the dawn of the Space Age. Today literally thousands of robotic spacecraft have been launched, many of which have flown to far-flung regions of the Solar System carrying with them the human spirit of scientific discovery and exploration. Numerous other satellites have been launched in orbit around the Earth providing services that support our technological society on the ground. How Spacecraft Fly: Spaceflight Without Formulae by Graham Swinerd focuses on how these spacecraft work. The book opens with a historical perspective of how we have come to understand our Solar System and the Universe. It then progresses through orbital flight, rocket science, the hostile environment within which spacecraft operate, and how they are designed. The concluding chapters give a glimpse of what the 21st century may ...

Optimal Autonomous Spacecraft Resiliency Maneuvers Using Metaheuristics

Science.gov (United States)

2014-09-15

This work was accepted for published by the American Institute of Aeronautics and Astronautics (AIAA) Journal of Spacecraft and Rockets in July 2014...publication in the AIAA Journal of Spacecraft and Rockets . Chapter 5 introduces an impulsive maneuvering strategy to deliver a spacecraft to its final...upon arrival r2 and v2 , respectively. The variable T2 determines the time of flight needed to make the maneuver, and the variable θ2 determines the

Integrating standard operating procedures with spacecraft automation, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Spacecraft automation has the potential to assist crew members and spacecraft operators in managing spacecraft systems during extended space missions. Automation can...

Quick Spacecraft Thermal Analysis Tool, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — For spacecraft design and development teams concerned with cost and schedule, the Quick Spacecraft Thermal Analysis Tool (QuickSTAT) is an innovative software suite...

Revamping Spacecraft Operational Intelligence

Science.gov (United States)

Hwang, Victor

2012-01-01

The EPOXI flight mission has been testing a new commercial system, Splunk, which employs data mining techniques to organize and present spacecraft telemetry data in a high-level manner. By abstracting away data-source specific details, Splunk unifies arbitrary data formats into one uniform system. This not only reduces the time and effort for retrieving relevant data, but it also increases operational visibility by allowing a spacecraft team to correlate data across many different sources. Splunk's scalable architecture coupled with its graphing modules also provide a solid toolset for generating data visualizations and building real-time applications such as browser-based telemetry displays.

Design feasibility via ascent optimality for next-generation spacecraft

Science.gov (United States)

Miele, A.; Mancuso, S.

This paper deals with the optimization of the ascent trajectories for single-stage-sub-orbit (SSSO), single-stage-to-orbit (SSTO), and two-stage-to-orbit (TSTO) rocket-powered spacecraft. The maximum payload weight problem is studied for different values of the engine specific impulse and spacecraft structural factor. The main conclusions are that: feasibility of SSSO spacecraft is guaranteed for all the parameter combinations considered; feasibility of SSTO spacecraft depends strongly on the parameter combination chosen; not only feasibility of TSTO spacecraft is guaranteed for all the parameter combinations considered, but the TSTO payload is several times the SSTO payload. Improvements in engine specific impulse and spacecraft structural factor are desirable and crucial for SSTO feasibility; indeed, aerodynamic improvements do not yield significant improvements in payload. For SSSO, SSTO, and TSTO spacecraft, simple engineering approximations are developed connecting the maximum payload weight to the engine specific impulse and spacecraft structural factor. With reference to the specific impulse/structural factor domain, these engineering approximations lead to the construction of zero-payload lines separating the feasibility region (positive payload) from the unfeasibility region (negative payload).

Research-Based Monitoring, Prediction, and Analysis Tools of the Spacecraft Charging Environment for Spacecraft Users

Science.gov (United States)

Zheng, Yihua; Kuznetsova, Maria M.; Pulkkinen, Antti A.; Maddox, Marlo M.; Mays, Mona Leila

2015-01-01

The Space Weather Research Center (http://swrc. gsfc.nasa.gov) at NASA Goddard, part of the Community Coordinated Modeling Center (http://ccmc.gsfc.nasa.gov), is committed to providing research-based forecasts and notifications to address NASA's space weather needs, in addition to its critical role in space weather education. It provides a host of services including spacecraft anomaly resolution, historical impact analysis, real-time monitoring and forecasting, tailored space weather alerts and products, and weekly summaries and reports. In this paper, we focus on how (near) real-time data (both in space and on ground), in combination with modeling capabilities and an innovative dissemination system called the integrated Space Weather Analysis system (http://iswa.gsfc.nasa.gov), enable monitoring, analyzing, and predicting the spacecraft charging environment for spacecraft users. Relevant tools and resources are discussed.

Industry perspectives on Plug-& -Play Spacecraft Avionics

Science.gov (United States)

Franck, R.; Graven, P.; Liptak, L.

This paper describes the methodologies and findings from an industry survey of awareness and utility of Spacecraft Plug-& -Play Avionics (SPA). The survey was conducted via interviews, in-person and teleconference, with spacecraft prime contractors and suppliers. It focuses primarily on AFRL's SPA technology development activities but also explores the broader applicability and utility of Plug-& -Play (PnP) architectures for spacecraft. Interviews include large and small suppliers as well as large and small spacecraft prime contractors. Through these “ product marketing” interviews, awareness and attitudes can be assessed, key technical and market barriers can be identified, and opportunities for improvement can be uncovered. Although this effort focuses on a high-level assessment, similar processes can be used to develop business cases and economic models which may be necessary to support investment decisions.

Multiple spacecraft observations of interplanetary shocks: four spacecraft determination of shock normals

International Nuclear Information System (INIS)

Russell, C.T.; Mellott, M.M.; Smith, E.J.; King, J.H.

1983-01-01

ISEE 1,2,3 IMP8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for furture techniques. When the angle between upstream and downstream magnetic field is greater than 20, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, we recommend using overdetermined shock normal solutions whenever possible, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints

Low cost spacecraft computers: Oxymoron or future trend?

Science.gov (United States)

Manning, Robert M.

1993-01-01

Over the last few decades, application of current terrestrial computer technology in embedded spacecraft control systems has been expensive and wrought with many technical challenges. These challenges have centered on overcoming the extreme environmental constraints (protons, neutrons, gamma radiation, cosmic rays, temperature, vibration, etc.) that often preclude direct use of commercial off-the-shelf computer technology. Reliability, fault tolerance and power have also greatly constrained the selection of spacecraft control system computers. More recently, new constraints are being felt, cost and mass in particular, that have again narrowed the degrees of freedom spacecraft designers once enjoyed. This paper discusses these challenges, how they were previously overcome, how future trends in commercial computer technology will simplify (or hinder) selection of computer technology for spacecraft control applications, and what spacecraft electronic system designers can do now to circumvent them.

Spacecraft design project: Low Earth orbit communications satellite

Science.gov (United States)

Moroney, Dave; Lashbrook, Dave; Mckibben, Barry; Gardener, Nigel; Rivers, Thane; Nottingham, Greg; Golden, Bill; Barfield, Bill; Bruening, Joe; Wood, Dave

1991-01-01

This is the final product of the spacecraft design project completed to fulfill the academic requirements of the Spacecraft Design and Integration 2 course (AE-4871) taught at the U.S. Naval Postgraduate School. The Spacecraft Design and Integration 2 course is intended to provide students detailed design experience in selection and design of both satellite system and subsystem components, and their location and integration into a final spacecraft configuration. The design team pursued a design to support a Low Earth Orbiting (LEO) communications system (GLOBALSTAR) currently under development by the Loral Cellular Systems Corporation. Each of the 14 team members was assigned both primary and secondary duties in program management or system design. Hardware selection, spacecraft component design, analysis, and integration were accomplished within the constraints imposed by the 11 week academic schedule and the available design facilities.

Developing Sustainable Spacecraft Water Management Systems

Science.gov (United States)

Thomas, Evan A.; Klaus, David M.

2009-01-01

It is well recognized that water handling systems used in a spacecraft are prone to failure caused by biofouling and mineral scaling, which can clog mechanical systems and degrade the performance of capillary-based technologies. Long duration spaceflight applications, such as extended stays at a Lunar Outpost or during a Mars transit mission, will increasingly benefit from hardware that is generally more robust and operationally sustainable overtime. This paper presents potential design and testing considerations for improving the reliability of water handling technologies for exploration spacecraft. Our application of interest is to devise a spacecraft wastewater management system wherein fouling can be accommodated by design attributes of the management hardware, rather than implementing some means of preventing its occurrence.

Relativistic Spacecraft Propelled by Directed Energy

Science.gov (United States)

Kulkarni, Neeraj; Lubin, Philip; Zhang, Qicheng

2018-04-01

Achieving relativistic flight to enable extrasolar exploration is one of the dreams of humanity and the long-term goal of our NASA Starlight program. We derive a relativistic solution for the motion of a spacecraft propelled by radiation pressure from a directed energy (DE) system. Depending on the system parameters, low-mass spacecraft can achieve relativistic speeds, thus enabling interstellar exploration. The diffraction of the DE system plays an important role and limits the maximum speed of the spacecraft. We consider “photon recycling” as a possible method to achieving higher speeds. We also discuss recent claims that our previous work on this topic is incorrect and show that these claims arise from an improper treatment of causality.

Time Frequency Analysis of Spacecraft Propellant Tank Spinning Slosh

Science.gov (United States)

Green, Steven T.; Burkey, Russell C.; Sudermann, James

2010-01-01

Many spacecraft are designed to spin about an axis along the flight path as a means of stabilizing the attitude of the spacecraft via gyroscopic stiffness. Because of the assembly requirements of the spacecraft and the launch vehicle, these spacecraft often spin about an axis corresponding to a minor moment of inertia. In such a case, any perturbation of the spin axis will cause sloshing motions in the liquid propellant tanks that will eventually dissipate enough kinetic energy to cause the spin axis nutation (wobble) to grow further. This spinning slosh and resultant nutation growth is a primary design problem of spinning spacecraft and one that is not easily solved by analysis or simulation only. Testing remains the surest way to address spacecraft nutation growth. This paper describes a test method and data analysis technique that reveal the resonant frequency and damping behavior of liquid motions in a spinning tank. Slosh resonant frequency and damping characteristics are necessary inputs to any accurate numerical dynamic simulation of the spacecraft.

REQUIREMENTS FOR IMAGE QUALITY OF EMERGENCY SPACECRAFTS

Directory of Open Access Journals (Sweden)

A. I. Altukhov

2015-05-01

Full Text Available The paper deals with the method for formation of quality requirements to the images of emergency spacecrafts. The images are obtained by means of remote sensing of near-earth space orbital deployment in the visible range. of electromagnetic radiation. The method is based on a joint taking into account conditions of space survey, characteristics of surveillance equipment, main design features of the observed spacecrafts and orbital inspection tasks. Method. Quality score is the predicted linear resolution image that gives the possibility to create a complete view of pictorial properties of the space image obtained by electro-optical system from the observing satellite. Formulation of requirements to the numerical value of this indicator is proposed to perform based on the properties of remote sensing system, forming images in the conditions of outer space, and the properties of the observed emergency spacecraft: dimensions, platform construction of the satellite, on-board equipment placement. For method implementation the authors have developed a predictive model of requirements to a linear resolution for images of emergency spacecrafts, making it possible to select the intervals of space shooting and get the satellite images required for quality interpretation. Main results. To verify the proposed model functionality we have carried out calculations of the numerical values for the linear resolution of the image, ensuring the successful task of determining the gross structural damage of the spacecrafts and identifying changes in their spatial orientation. As input data were used with dimensions and geometric primitives corresponding to the shape of deemed inspected spacecrafts: Resurs-P", "Canopus-B", "Electro-L". Numerical values of the linear resolution images have been obtained, ensuring the successful task solution for determining the gross structural damage of spacecrafts.

Robust Spacecraft Component Detection in Point Clouds

Directory of Open Access Journals (Sweden)

Quanmao Wei

2018-03-01

Full Text Available Automatic component detection of spacecraft can assist in on-orbit operation and space situational awareness. Spacecraft are generally composed of solar panels and cuboidal or cylindrical modules. These components can be simply represented by geometric primitives like plane, cuboid and cylinder. Based on this prior, we propose a robust automatic detection scheme to automatically detect such basic components of spacecraft in three-dimensional (3D point clouds. In the proposed scheme, cylinders are first detected in the iteration of the energy-based geometric model fitting and cylinder parameter estimation. Then, planes are detected by Hough transform and further described as bounded patches with their minimum bounding rectangles. Finally, the cuboids are detected with pair-wise geometry relations from the detected patches. After successive detection of cylinders, planar patches and cuboids, a mid-level geometry representation of the spacecraft can be delivered. We tested the proposed component detection scheme on spacecraft 3D point clouds synthesized by computer-aided design (CAD models and those recovered by image-based reconstruction, respectively. Experimental results illustrate that the proposed scheme can detect the basic geometric components effectively and has fine robustness against noise and point distribution density.

Robust Spacecraft Component Detection in Point Clouds.

Science.gov (United States)

Wei, Quanmao; Jiang, Zhiguo; Zhang, Haopeng

2018-03-21

Automatic component detection of spacecraft can assist in on-orbit operation and space situational awareness. Spacecraft are generally composed of solar panels and cuboidal or cylindrical modules. These components can be simply represented by geometric primitives like plane, cuboid and cylinder. Based on this prior, we propose a robust automatic detection scheme to automatically detect such basic components of spacecraft in three-dimensional (3D) point clouds. In the proposed scheme, cylinders are first detected in the iteration of the energy-based geometric model fitting and cylinder parameter estimation. Then, planes are detected by Hough transform and further described as bounded patches with their minimum bounding rectangles. Finally, the cuboids are detected with pair-wise geometry relations from the detected patches. After successive detection of cylinders, planar patches and cuboids, a mid-level geometry representation of the spacecraft can be delivered. We tested the proposed component detection scheme on spacecraft 3D point clouds synthesized by computer-aided design (CAD) models and those recovered by image-based reconstruction, respectively. Experimental results illustrate that the proposed scheme can detect the basic geometric components effectively and has fine robustness against noise and point distribution density.

Analysis of Solar Wind Precipitation on Mars Using MAVEN/SWIA Observations of Spacecraft-Scattered Ions

Science.gov (United States)

Lue, C.; Halekas, J. S.

2017-12-01

Particle sensors on the MAVEN spacecraft (SWIA, SWEA, STATIC) observe precipitating solar wind ions during MAVEN's periapsis passes in the Martian atmosphere (at 120-250 km altitude). The signature is observed as positive and negative particles at the solar wind energy, traveling away from the Sun. The observations can be explained by the solar wind penetrating the Martian magnetic barrier in the form of energetic neutral atoms (ENAs) due to charge-exchange with the Martian hydrogen corona, and then being reionized in positive or negative form upon impact with the atmosphere (1). These findings have elucidated solar wind precipitation dynamics at Mars, and can also be used to monitor the solar wind even when MAVEN is at periapsis (2). In the present study, we focus on a SWIA instrument background signal that has been interpreted as spacecraft/instrument-scattered ions (2). We aim to model and subtract the scattered ion signal from the observations including those of reionized solar wind. We also aim to use the scattered ion signal to track hydrogen ENAs impacting the spacecraft above the reionization altitude. We characterize the energy spectrum and directional scattering function for solar wind scattering off the SWIA aperture structure, the radome and the spacecraft body. We find a broad scattered-ion energy spectrum up to the solar wind energy, displaying increased energy loss and reduced flux with increasing scattering angle, allowing correlations with the solar wind direction, energy, and flux. We develop models that can be used to predict the scattered signal based on the direct solar wind observations or to infer the solar wind properties based on the observed scattered signal. We then investigate deviations to the models when the spacecraft is in the Martian atmosphere and evaluate the plausibility of that these are caused by ENAs. We also perform SIMION modeling of the scattering process and the resulting signal detection by SWIA, to study the results from

Nuclear-powered Hysat spacecraft: comparative design study

International Nuclear Information System (INIS)

Raab, B.

1975-08-01

The study shows that the all-nuclear spacecraft can have a substantial weight advantage over a hybrid (nuclear/solar) or all-solar spacecraft, owing to a further reduction in power requirement, and to the elimination of such equipment as the sensor gimbal and rotating joint assemblies. Because the need for a sun-oriented section is eliminated, the all-nuclear spacecraft can be designed as a monolithic structure, with the sensor and other payload firmly secured in a fixed position on the structure. This enhances attitude stability while minimizing structural weight and eliminating the need for flexible fluid lines. Sensor motion can be produced, varied, and controlled within the limits specified by the study contractors by moving the entire spacecraft in the prescribed pattern. A simple attitude control system using available hardware suffices to meet all requirements

Automated constraint checking of spacecraft command sequences

Science.gov (United States)

Horvath, Joan C.; Alkalaj, Leon J.; Schneider, Karl M.; Spitale, Joseph M.; Le, Dang

1995-01-01

Robotic spacecraft are controlled by onboard sets of commands called "sequences." Determining that sequences will have the desired effect on the spacecraft can be expensive in terms of both labor and computer coding time, with different particular costs for different types of spacecraft. Specification languages and appropriate user interface to the languages can be used to make the most effective use of engineering validation time. This paper describes one specification and verification environment ("SAVE") designed for validating that command sequences have not violated any flight rules. This SAVE system was subsequently adapted for flight use on the TOPEX/Poseidon spacecraft. The relationship of this work to rule-based artificial intelligence and to other specification techniques is discussed, as well as the issues that arise in the transfer of technology from a research prototype to a full flight system.

Advanced Solar-propelled Cargo Spacecraft for Mars Missions

Science.gov (United States)

Auziasdeturenne, Jacqueline; Beall, Mark; Burianek, Joseph; Cinniger, Anna; Dunmire, Barbrina; Haberman, Eric; Iwamoto, James; Johnson, Stephen; Mccracken, Shawn; Miller, Melanie

1989-01-01

Three concepts for an unmanned, solar powered, cargo spacecraft for Mars support missions were investigated. These spacecraft are designed to carry a 50,000 kg payload from a low Earth orbit to a low Mars orbit. Each design uses a distinctly different propulsion system: A Solar Radiation Absorption (SRA) system, a Solar-Pumped Laser (SPL) system and a solar powered magnetoplasmadynamic (MPD) arc system. The SRA directly converts solar energy to thermal energy in the propellant through a novel process. In the SPL system, a pair of solar-pumped, multi-megawatt, CO2 lasers in sunsynchronous Earth orbit converts solar energy to laser energy. The MPD system used indium phosphide solar cells to convert sunlight to electricity, which powers the propulsion system. Various orbital transfer options are examined for these concepts. In the SRA system, the mother ship transfers the payload into a very high Earth orbit and a small auxiliary propulsion system boosts the payload into a Hohmann transfer to Mars. The SPL spacecraft and the SPL powered spacecraft return to Earth for subsequent missions. The MPD propelled spacecraft, however, remains at Mars as an orbiting space station. A patched conic approximation was used to determine a heliocentric interplanetary transfer orbit for the MPD propelled spacecraft. All three solar-powered spacecraft use an aerobrake procedure to place the payload into a low Mars parking orbit. The payload delivery times range from 160 days to 873 days (2.39 years).

Modeling the fundamental characteristics and processes of the spacecraft functioning

Science.gov (United States)

Bazhenov, V. I.; Osin, M. I.; Zakharov, Y. V.

1986-01-01

The fundamental aspects of modeling of spacecraft characteristics by using computing means are considered. Particular attention is devoted to the design studies, the description of physical appearance of the spacecraft, and simulated modeling of spacecraft systems. The fundamental questions of organizing the on-the-ground spacecraft testing and the methods of mathematical modeling were presented.

Spacecraft Dynamics Should be Considered in Kalman Filter Attitude Estimation

Science.gov (United States)

Yang, Yaguang; Zhou, Zhiqiang

2016-01-01

Kalman filter based spacecraft attitude estimation has been used in some high-profile missions and has been widely discussed in literature. While some models in spacecraft attitude estimation include spacecraft dynamics, most do not. To our best knowledge, there is no comparison on which model is a better choice. In this paper, we discuss the reasons why spacecraft dynamics should be considered in the Kalman filter based spacecraft attitude estimation problem. We also propose a reduced quaternion spacecraft dynamics model which admits additive noise. Geometry of the reduced quaternion model and the additive noise are discussed. This treatment is more elegant in mathematics and easier in computation. We use some simulation example to verify our claims.

Spacecraft Multiple Array Communication System Performance Analysis

Science.gov (United States)

Hwu, Shian U.; Desilva, Kanishka; Sham, Catherine C.

2010-01-01

The Communication Systems Simulation Laboratory (CSSL) at the NASA Johnson Space Center is tasked to perform spacecraft and ground network communication system simulations, design validation, and performance verification. The CSSL has developed simulation tools that model spacecraft communication systems and the space and ground environment in which the tools operate. In this paper, a spacecraft communication system with multiple arrays is simulated. Multiple array combined technique is used to increase the radio frequency coverage and data rate performance. The technique is to achieve phase coherence among the phased arrays to combine the signals at the targeting receiver constructively. There are many technical challenges in spacecraft integration with a high transmit power communication system. The array combining technique can improve the communication system data rate and coverage performances without increasing the system transmit power requirements. Example simulation results indicate significant performance improvement can be achieved with phase coherence implementation.

Spacecraft Spin Test Facility

Data.gov (United States)

Federal Laboratory Consortium — FUNCTION: Provides the capability to correct unbalances of spacecraft by using dynamic measurement techniques and static/coupled measurements to provide products of...

Spacecraft Swarm Coordination and Planning Tool, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Fractionated spacecraft architectures to distribute mission performance from a single, monolithic satellite across large number of smaller spacecraft, for missions...

Attitude Estimation in Fractionated Spacecraft Cluster Systems

Science.gov (United States)

Hadaegh, Fred Y.; Blackmore, James C.

2011-01-01

An attitude estimation was examined in fractioned free-flying spacecraft. Instead of a single, monolithic spacecraft, a fractionated free-flying spacecraft uses multiple spacecraft modules. These modules are connected only through wireless communication links and, potentially, wireless power links. The key advantage of this concept is the ability to respond to uncertainty. For example, if a single spacecraft module in the cluster fails, a new one can be launched at a lower cost and risk than would be incurred with onorbit servicing or replacement of the monolithic spacecraft. In order to create such a system, however, it is essential to know what the navigation capabilities of the fractionated system are as a function of the capabilities of the individual modules, and to have an algorithm that can perform estimation of the attitudes and relative positions of the modules with fractionated sensing capabilities. Looking specifically at fractionated attitude estimation with startrackers and optical relative attitude sensors, a set of mathematical tools has been developed that specify the set of sensors necessary to ensure that the attitude of the entire cluster ( cluster attitude ) can be observed. Also developed was a navigation filter that can estimate the cluster attitude if these conditions are satisfied. Each module in the cluster may have either a startracker, a relative attitude sensor, or both. An extended Kalman filter can be used to estimate the attitude of all modules. A range of estimation performances can be achieved depending on the sensors used and the topology of the sensing network.

Attitude and Configuration Control of Flexible Multi-Body Spacecraft

Science.gov (United States)

Cho, Sung-Ki; Cochran, John E., Jr.

2002-06-01

Multi-body spacecraft attitude and configuration control formulations based on the use of collaborative control theory are considered. The control formulations are based on two-player, nonzero-sum, differential game theory applied using a Nash strategy. It is desired that the control laws allow different components of the multi-body system to perform different tasks. For example, it may be desired that one body points toward a fixed star while another body in the system slews to track another satellite. Although similar to the linear quadratic regulator formulation, the collaborative control formulation contains a number of additional design parameters because the problem is formulated as two control problems coupled together. The use of the freedom of the partitioning of the total problem into two coupled control problems and the selection of the elements of the cross-coupling matrices are specific problems addressed in this paper. Examples are used to show that significant improvement in performance, as measured by realistic criteria, of collaborative control over conventional linear quadratic regulator control can be achieved by using proposed design guidelines.

Attitude and Configuration Control of Flexible Multi-Body Spacecraft

Directory of Open Access Journals (Sweden)

Sungki Cho

2002-06-01

Full Text Available Multi-body spacecraft attitude and configuration control formulations based on the use of collaborative control theory are considered. The control formulations are based on two-player, nonzero-sum, differential game theory applied using a Nash strategy. It is desired that the control laws allow different components of the multi-body system to perform different tasks. For example, it may be desired that one body points toward a fixed star while another body in the system slews to track another satellite. Although similar to the linear quadratic regulator formulation, the collaborative control formulation contains a number of additional design parameters because the problem is formulated as two control problems coupled together. The use of the freedom of the partitioning of the total problem into two coupled control problems and the selection of the elements of the cross-coupling matrices are specific problems addressed in this paper. Examples are used to show that significant improvement in performance, as measured by realistic criteria, of collaborative control over conventional linear quadratic regulator control can be achieved by using proposed design guidelines.

Maximum-likelihood-based extended-source spatial acquisition and tracking for planetary optical communications

Science.gov (United States)

Tsou, Haiping; Yan, Tsun-Yee

1999-04-01

This paper describes an extended-source spatial acquisition and tracking scheme for planetary optical communications. This scheme uses the Sun-lit Earth image as the beacon signal, which can be computed according to the current Sun-Earth-Probe angle from a pre-stored Earth image or a received snapshot taken by other Earth-orbiting satellite. Onboard the spacecraft, the reference image is correlated in the transform domain with the received image obtained from a detector array, which is assumed to have each of its pixels corrupted by an independent additive white Gaussian noise. The coordinate of the ground station is acquired and tracked, respectively, by an open-loop acquisition algorithm and a closed-loop tracking algorithm derived from the maximum likelihood criterion. As shown in the paper, the optimal spatial acquisition requires solving two nonlinear equations, or iteratively solving their linearized variants, to estimate the coordinate when translation in the relative positions of onboard and ground transceivers is considered. Similar assumption of linearization leads to the closed-loop spatial tracking algorithm in which the loop feedback signals can be derived from the weighted transform-domain correlation. Numerical results using a sample Sun-lit Earth image demonstrate that sub-pixel resolutions can be achieved by this scheme in a high disturbance environment.

Mesh Network Architecture for Enabling Inter-Spacecraft Communication

Science.gov (United States)

Becker, Christopher; Merrill, Garrick

2017-01-01

To enable communication between spacecraft operating in a formation or small constellation, a mesh network architecture was developed and tested using a time division multiple access (TDMA) communication scheme. The network is designed to allow for the exchange of telemetry and other data between spacecraft to enable collaboration between small spacecraft. The system uses a peer-to-peer topology with no central router, so that it does not have a single point of failure. The mesh network is dynamically configurable to allow for addition and subtraction of new spacecraft into the communication network. Flight testing was performed using an unmanned aerial system (UAS) formation acting as a spacecraft analogue and providing a stressing environment to prove mesh network performance. The mesh network was primarily devised to provide low latency, high frequency communication but is flexible and can also be configured to provide higher bandwidth for applications desiring high data throughput. The network includes a relay functionality that extends the maximum range between spacecraft in the network by relaying data from node to node. The mesh network control is implemented completely in software making it hardware agnostic, thereby allowing it to function with a wide variety of existing radios and computing platforms..

Airborne particulate matter in spacecraft

Science.gov (United States)

1988-01-01

Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization.

Fifty-one years of Los Alamos Spacecraft

Energy Technology Data Exchange (ETDEWEB)

Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-09-04

From 1963 to 2014, the Los Alamos National Laboratory was involved in at least 233 spacecraft. There are probably only one or two institutions in the world that have been involved in so many spacecraft. Los Alamos space exploration started with the Vela satellites for nuclear test detection, but soon expanded to ionospheric research (mostly barium releases), radioisotope thermoelectric generators, solar physics, solar wind, magnetospheres, astrophysics, national security, planetary physics, earth resources, radio propagation in the ionosphere, and cubesats. Here, we present a list of the spacecraft, their purpose, and their launch dates for use during RocketFest

Ka-band Technologies for Small Spacecraft Communications via Relays and Direct Data Downlink

Science.gov (United States)

Budinger, James M.; Niederhaus, Charles; Reinhart, Richard; Downey, Joe; Roberts, Anthony

2016-01-01

As the scientific capabilities and number of small spacecraft missions in the near Earth region increase, standard yet configurable user spacecraft terminals operating in Ka-band are needed to lower mission cost and risk and enable significantly higher data return than current UHF or S-band terminals. These compact Ka-band terminals are intended to operate with both the current and next generation of Ka-band relay satellites and via direct data communications with near Earth tracking terminals. This presentation provides an overview of emerging NASA-sponsored and commercially provided technologies in software defined radios (SDRs), transceivers, and electronically steered antennas that will enable data rates from hundreds of kbps to over 1 Gbps and operate in multiple frequency bands (such as S- and X-bands) and expand the use of NASA's common Ka-bands frequencies: 22.55-23.15 GHz for forward data or uplink; and 25.5-27.0 GHz for return data or downlink. Reductions in mass, power and volume come from integration of multiple radio functions, operations in Ka-band, high efficiency amplifiers and receivers, and compact, flat and vibration free electronically steered narrow beam antennas for up to + 60 degrees field of regard. The software defined near Earth space transceiver (SD-NEST) described in the presentation is intended to be compliant with NASA's space telecommunications radio system (STRS) standard for communications waveforms and hardware interoperability.

Training for spacecraft technical analysts

Science.gov (United States)

Ayres, Thomas J.; Bryant, Larry

1989-01-01

Deep space missions such as Voyager rely upon a large team of expert analysts who monitor activity in the various engineering subsystems of the spacecraft and plan operations. Senior teammembers generally come from the spacecraft designers, and new analysts receive on-the-job training. Neither of these methods will suffice for the creation of a new team in the middle of a mission, which may be the situation during the Magellan mission. New approaches are recommended, including electronic documentation, explicit cognitive modeling, and coached practice with archived data.

Low power arcjet system spacecraft impacts

Science.gov (United States)

Pencil, Eric J.; Sarmiento, Charles J.; Lichtin, D. A.; Palchefsky, J. W.; Bogorad, A. L.

1993-01-01

Potential plume contamination of spacecraft surfaces was investigated by positioning spacecraft material samples relative to an arcjet thruster. Samples in the simulated solar array region were exposed to the cold gas arcjet plume for 40 hrs to address concerns about contamination by backstreaming diffusion pump oil. Except for one sample, no significant changes were measured in absorptance and emittance within experimental error. Concerns about surface property degradation due to electrostatic discharges led to the investigation of the discharge phenomenon of charged samples during arcjet ignition. Short duration exposure of charged samples demonstrated that potential differences are consistently and completely eliminated within the first second of exposure to a weakly ionized plume. The spark discharge mechanism was not the discharge phenomenon. The results suggest that the arcjet could act as a charge control device on spacecraft.

Multi-spacecraft observations of solar hard X-ray bursts

International Nuclear Information System (INIS)

Kane, S.R.

1981-01-01

The role of multi-spacecraft observations in solar flare research is examined from the point of view of solar hard X-ray bursts and their implications with respect to models of the impulsive phase. Multi-spacecraft measurements provide a stereoscopic view of the flare region, and hence represent the only direct method of measuring directivity of X-rays. In absence of hard X-ray imaging instruments with high spatial and temporal resolution, multi-spacecraft measurements provide the only means of determining the radial (vertical) structure of the hard X-ray source. This potential of the multi-spacecraft observations is illustrated with an analysis of the presently available observations of solar hard X-ray bursts made simultaneously by two or more of the following spacecraft: International Sun Earth Explorer-3 (ISEE-3), Pioneer Venus Orbiter (PVO), Helios-B and High Energy Astrophysical Observatory-A (HEAO-A). In particular, some conclusions have been drawn about the spatial structure and directivity of 50-100 keV X-rays from impulsive flares. Desirable features of future multi-spacecraft missions are briefly discussed followed by a short description of the hard X-ray experiment on the International Solar Polar Mission which has been planned specifically for multi-spacecraft observations of the Sun. (orig.)

Multiple spacecraft observations of interplanetary shocks Four spacecraft determination of shock normals

Science.gov (United States)

Russell, C. T.; Mellott, M. M.; Smith, E. J.; King, J. H.

1983-01-01

ISEE 1, 2, 3, IMP 8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for future investigations these data allow the evaluation of the accuracy of several shock normal determination techniques. When the angle between upstream and downstream magnetic field is greater than 20 deg, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, the use of overdetermined shock normal solutions, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints, is recommended whenever possible.

Standardized spacecraft: a methodology for decision making. AMS report No. 1199

International Nuclear Information System (INIS)

Greenberg, J.S.; Nichols, R.A.

1974-01-01

As the space program matures, more and more attention is being focused on ways to reduce the costs of performing space missions. Standardization has been suggested as a way of providing cost reductions. The question of standardization at the system level, in particular, the question of the desirability of spacecraft standardization for geocentric space missions is addressed. The spacecraft is considered to be a bus upon which mission oriented equipment, the payload, is mounted. Three basic questions are considered: (1) is spacecraft standardization economically desirable; (2) if spacecraft standardization is economically desirable, what standardized spacecraft configuration or mix of configurations and technologies should be developed; and (3) if standardized spacecraft are to be developed, what power levels should they be designed for. A methodology which has been developed and which is necessary to follow if the above questions are to be answered and informed decisions made relative to spacecraft standardization is described. To illustrate the decision making problems and the need for the developed methodology and the data requirements, typical standardized spacecraft have been considered. Both standardized solar and nuclear-powered spacecraft and mission specialized spacecraft have been conceptualized and performance and cost estimates have been made. These estimates are not considered to be of sufficient accuracy to allow decisions regarding spacecraft mix and power levels to be made at this time. The estimates are deemed of sufficient accuracy so as to demonstrate the desirability of spacecraft standardization and the methodology (as well as the need for the methodology) which is necessary to decide upon the best mix of standardized spacecraft and their design power levels. (U.S.)

Spacecraft Material Outgassing Data

Data.gov (United States)

National Aeronautics and Space Administration — This compilation of outgassing data of materials intended for spacecraft use were obtained at the Goddard Space Flight Center (GSFC), utilizing equipment developed...

High-Performance Fire Detector for Spacecraft, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The danger from fire aboard spacecraft is immediate with only moments for detection and suppression. Spacecraft are unique high-value systems where the cost of...

Gravity and Nonconservative Force Model Tuning for the GEOSAT Follow-On Spacecraft

Science.gov (United States)

Lemoine, Frank G.; Zelensky, Nikita P.; Rowlands, David D.; Luthcke, Scott B.; Chinn, Douglas S.; Marr, Gregory C.; Smith, David E. (Technical Monitor)

2000-01-01

The US Navy's GEOSAT Follow-On spacecraft was launched on February 10, 1998 and the primary objective of the mission was to map the oceans using a radar altimeter. Three radar altimeter calibration campaigns have been conducted in 1999 and 2000. The spacecraft is tracked by satellite laser ranging (SLR) and Doppler beacons and a limited amount of data have been obtained from the Global Positioning Receiver (GPS) on board the satellite. Even with EGM96, the predicted radial orbit error due to gravity field mismodelling (to 70x70) remains high at 2.61 cm (compared to 0.88 cm for TOPEX). We report on the preliminary gravity model tuning for GFO using SLR, and altimeter crossover data. Preliminary solutions using SLR and GFO/GFO crossover data from CalVal campaigns I and II in June-August 1999, and January-February 2000 have reduced the predicted radial orbit error to 1.9 cm and further reduction will be possible when additional data are added to the solutions. The gravity model tuning has improved principally the low order m-daily terms and has reduced significantly the geographically correlated error present in this satellite orbit. In addition to gravity field mismodelling, the largest contributor to the orbit error is the non-conservative force mismodelling. We report on further nonconservative force model tuning results using available data from over one cycle in beta prime.

Electromagnetic Forces on a Relativistic Spacecraft in the Interstellar Medium

Energy Technology Data Exchange (ETDEWEB)

Hoang, Thiem [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of); Loeb, Abraham, E-mail: thiemhoang@kasi.re.kr, E-mail: aloeb@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States)

2017-10-10

A relativistic spacecraft of the type envisioned by the Breakthrough Starshot initiative will inevitably become charged through collisions with interstellar particles and UV photons. Interstellar magnetic fields would therefore deflect the trajectory of the spacecraft. We calculate the expected deflection for typical interstellar conditions. We also find that the charge distribution of the spacecraft is asymmetric, producing an electric dipole moment. The interaction between the moving electric dipole and the interstellar magnetic field is found to produce a large torque, which can result in fast oscillation of the spacecraft around the axis perpendicular to the direction of motion, with a period of ∼0.5 hr. We then study the spacecraft rotation arising from impulsive torques by dust bombardment. Finally, we discuss the effect of the spacecraft rotation and suggest several methods to mitigate it.

Autonomous Spacecraft Communication Interface for Load Planning

Science.gov (United States)

Dever, Timothy P.; May, Ryan D.; Morris, Paul H.

2014-01-01

Ground-based controllers can remain in continuous communication with spacecraft in low Earth orbit (LEO) with near-instantaneous communication speeds. This permits near real-time control of all of the core spacecraft systems by ground personnel. However, as NASA missions move beyond LEO, light-time communication delay issues, such as time lag and low bandwidth, will prohibit this type of operation. As missions become more distant, autonomous control of manned spacecraft will be required. The focus of this paper is the power subsystem. For present missions, controllers on the ground develop a complete schedule of power usage for all spacecraft components. This paper presents work currently underway at NASA to develop an architecture for an autonomous spacecraft, and focuses on the development of communication between the Mission Manager and the Autonomous Power Controller. These two systems must work together in order to plan future load use and respond to unanticipated plan deviations. Using a nominal spacecraft architecture and prototype versions of these two key components, a number of simulations are run under a variety of operational conditions, enabling development of content and format of the messages necessary to achieve the desired goals. The goals include negotiation of a load schedule that meets the global requirements (contained in the Mission Manager) and local power system requirements (contained in the Autonomous Power Controller), and communication of off-plan disturbances that arise while executing a negotiated plan. The message content is developed in two steps: first, a set of rapid-prototyping "paper" simulations are preformed; then the resultant optimized messages are codified for computer communication for use in automated testing.

Spacecraft Fire Safety Demonstration

Data.gov (United States)

National Aeronautics and Space Administration — The objective of the Spacecraft Fire Safety Demonstration project is to develop and conduct large-scale fire safety experiments on an International Space Station...

A generalized modal shock spectra method for spacecraft loads analysis. [internal loads in a spacecraft structure subjected to a dynamic launch environment

Science.gov (United States)

Trubert, M.; Salama, M.

1979-01-01

Unlike an earlier shock spectra approach, generalization permits an accurate elastic interaction between the spacecraft and launch vehicle to obtain accurate bounds on the spacecraft response and structural loads. In addition, the modal response from a previous launch vehicle transient analysis with or without a dummy spacecraft - is exploited to define a modal impulse as a simple idealization of the actual forcing function. The idealized modal forcing function is then used to derive explicit expressions for an estimate of the bound on the spacecraft structural response and forces. Greater accuracy is achieved with the present method over the earlier shock spectra, while saving much computational effort over the transient analysis.

Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

Science.gov (United States)

DeSimpelaere, Edward

2011-01-01

The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

Iodine Plasma (Electric Propulsion) Interaction with Spacecraft Materials

Science.gov (United States)

2016-12-28

Teflon (AGT5, Ag-FEP) Thermal control surface (radiator) Spacecraft Exposure Soda-lime glass (74% SiO2 , 13% Na2O, 8% CaO, 4% MgO, 1% other oxide... Glass Solar panel cover Spacecraft Exposure Buna-N (acrylonitrile butadiene rubber) Seals Iodine Feed System Carbon fiber composite (epoxy resin...Fe Propellant isolator Spacecraft Exposure Lanthanum Hexaboride, LaB6 Cathode emitter Inside Cathode Yes MACOR (46% SiO2 , 17% MgO, 16% Al2O3, 10

Development of a hardware-in-the-loop testbed to demonstrate multiple spacecraft operations in proximity

Science.gov (United States)

Eun, Youngho; Park, Sang-Young; Kim, Geuk-Nam

2018-06-01

This paper presents a new state-of-the-art ground-based hardware-in-the-loop test facility, which was developed to verify and demonstrate autonomous guidance, navigation, and control algorithms for space proximity operations and formation flying maneuvers. The test facility consists of two complete spaceflight simulators, an aluminum-based operational arena, and a set of infrared motion tracking cameras; thus, the testbed is capable of representing space activities under circumstances prevailing on the ground. The spaceflight simulators have a maximum of five-degree-of-freedom in a quasi-momentum-free environment, which is produced by a set of linear/hemispherical air-bearings and a horizontally leveled operational arena. The tracking system measures the real-time three-dimensional position and attitude to provide state variables to the agents. The design of the testbed is illustrated in detail for every element throughout the paper. The practical hardware characteristics of the active/passive measurement units and internal actuators are identified in detail from various perspectives. These experimental results support the successful development of the entire facility and enable us to implement and verify the spacecraft proximity operation strategy in the near future.

Time maintenance system for the BMDO MSX spacecraft

Science.gov (United States)

Hermes, Martin J.

1994-01-01

The Johns Hopkins University Applied Physics Laboratory (APL) is responsible for designing and implementing a clock maintenance system for the Ballistic Missile Defense Organizations (BMDO) Midcourse Space Experiment (MSX) spacecraft. The MSX spacecraft has an on-board clock that will be used to control execution of time-dependent commands and to time tag all science and housekeeping data received from the spacecraft. MSX mission objectives have dictated that this spacecraft time, UTC(MSX), maintain a required accuracy with respect to UTC(USNO) of +/- 10 ms with a +/- 1 ms desired accuracy. APL's atomic time standards and the downlinked spacecraft time were used to develop a time maintenance system that will estimate the current MSX clock time offset during an APL pass and make estimates of the clock's drift and aging using the offset estimates from many passes. Using this information, the clock's accuracy will be maintained by uplinking periodic clock correction commands. The resulting time maintenance system is a combination of offset measurement, command/telemetry, and mission planning hardware and computing assets. All assets provide necessary inputs for deciding when corrections to the MSX spacecraft clock must be made to maintain its required accuracy without inhibiting other mission objectives. The MSX time maintenance system is described as a whole and the clock offset measurement subsystem, a unique combination of precision time maintenance and measurement hardware controlled by a Macintosh computer, is detailed. Simulations show that the system estimates the MSX clock offset to less than+/- 33 microseconds.

LDEF materials results for spacecraft applications: Executive summary

Science.gov (United States)

Whitaker, A. F.; Dooling, D.

1995-03-01

To address the challenges of space environmental effects, NASA designed the Long Duration Exposure Facility (LDEF) for an 18-month mission to expose thousands of samples of candidate materials that might be used on a space station or other orbital spacecraft. LDEF was launched in April 1984 and was to have been returned to Earth in 1985. Changes in mission schedules postponed retrieval until January 1990, after 69 months in orbit. Analyses of the samples recovered from LDEF have provided spacecraft designers and managers with the most extensive data base on space materials phenomena. Many LDEF samples were greatly changed by extended space exposure. Among even the most radially altered samples, NASA and its science teams are finding a wealth of surprising conclusions and tantalizing clues about the effects of space on materials. Many were discussed at the first two LDEF results conferences and subsequent professional papers. The LDEF Materials Results for Spacecraft Applications Conference was convened in Huntsville to discuss implications for spacecraft design. Already, paint and thermal blanket selections for space station and other spacecraft have been affected by LDEF data. This volume synopsizes those results.

3D Display of Spacecraft Dynamics Using Real Telemetry

Directory of Open Access Journals (Sweden)

Sanguk Lee

2002-12-01

Full Text Available 3D display of spacecraft motion by using telemetry data received from satellite in real-time is described. Telemetry data are converted to the appropriate form for 3-D display by the real-time preprocessor. Stored playback telemetry data also can be processed for the display. 3D display of spacecraft motion by using real telemetry data provides intuitive comprehension of spacecraft dynamics.

Numerical Analysis of Magnetic Sail Spacecraft

International Nuclear Information System (INIS)

Sasaki, Daisuke; Yamakawa, Hiroshi; Usui, Hideyuki; Funaki, Ikkoh; Kojima, Hirotsugu

2008-01-01

To capture the kinetic energy of the solar wind by creating a large magnetosphere around the spacecraft, magneto-plasma sail injects a plasma jet into a strong magnetic field produced by an electromagnet onboard the spacecraft. The aim of this paper is to investigate the effect of the IMF (interplanetary magnetic field) on the magnetosphere of magneto-plasma sail. First, using an axi-symmetric two-dimensional MHD code, we numerically confirm the magnetic field inflation, and the formation of a magnetosphere by the interaction between the solar wind and the magnetic field. The expansion of an artificial magnetosphere by the plasma injection is then simulated, and we show that the magnetosphere is formed by the interaction between the solar wind and the magnetic field expanded by the plasma jet from the spacecraft. This simulation indicates the size of the artificial magnetosphere becomes smaller when applying the IMF.

Quick spacecraft charging primer

International Nuclear Information System (INIS)

Larsen, Brian Arthur

2014-01-01

This is a presentation in PDF format which is a quick spacecraft charging primer, meant to be used for program training. It goes into detail about charging physics, RBSP examples, and how to identify charging.

Research on intelligent power distribution system for spacecraft

Science.gov (United States)

Xia, Xiaodong; Wu, Jianju

2017-10-01

The power distribution system (PDS) mainly realizes the power distribution and management of the electrical load of the whole spacecraft, which is directly related to the success or failure of the mission, and hence is an important part of the spacecraft. In order to improve the reliability and intelligent degree of the PDS, and considering the function and composition of spacecraft power distribution system, this paper systematically expounds the design principle and method of the intelligent power distribution system based on SSPC, and provides the analysis and verification of the test data additionally.

Power requirements for commercial communications spacecraft

Science.gov (United States)

Billerbeck, W. J.

1985-01-01

Historical data on commercial spacecraft power systems are presented and their power requirements to the growth of satellite communications channel usage are related. Some approaches for estimating future power requirements of this class of spacecraft through the year 2000 are proposed. The key technology drivers in satellite power systems are addressed. Several technological trends in such systems are described, focusing on the most useful areas for research and development of major subsystems, including solar arrays, energy storage, and power electronics equipment.

Modeling SMAP Spacecraft Attitude Control Estimation Error Using Signal Generation Model

Science.gov (United States)

Rizvi, Farheen

2016-01-01

Two ground simulation software are used to model the SMAP spacecraft dynamics. The CAST software uses a higher fidelity model than the ADAMS software. The ADAMS software models the spacecraft plant, controller and actuator models, and assumes a perfect sensor and estimator model. In this simulation study, the spacecraft dynamics results from the ADAMS software are used as CAST software is unavailable. The main source of spacecraft dynamics error in the higher fidelity CAST software is due to the estimation error. A signal generation model is developed to capture the effect of this estimation error in the overall spacecraft dynamics. Then, this signal generation model is included in the ADAMS software spacecraft dynamics estimate such that the results are similar to CAST. This signal generation model has similar characteristics mean, variance and power spectral density as the true CAST estimation error. In this way, ADAMS software can still be used while capturing the higher fidelity spacecraft dynamics modeling from CAST software.

A Sampling Based Approach to Spacecraft Autonomous Maneuvering with Safety Specifications

Science.gov (United States)

Starek, Joseph A.; Barbee, Brent W.; Pavone, Marco

2015-01-01

This paper presents a methods for safe spacecraft autonomous maneuvering that leverages robotic motion-planning techniques to spacecraft control. Specifically the scenario we consider is an in-plan rendezvous of a chaser spacecraft in proximity to a target spacecraft at the origin of the Clohessy Wiltshire Hill frame. The trajectory for the chaser spacecraft is generated in a receding horizon fashion by executing a sampling based robotic motion planning algorithm name Fast Marching Trees (FMT) which efficiently grows a tree of trajectories over a set of probabillistically drawn samples in the state space. To enforce safety the tree is only grown over actively safe samples for which there exists a one-burn collision avoidance maneuver that circularizes the spacecraft orbit along a collision-free coasting arc and that can be executed under potential thrusters failures. The overall approach establishes a provably correct framework for the systematic encoding of safety specifications into the spacecraft trajectory generations process and appears amenable to real time implementation on orbit. Simulation results are presented for a two-fault tolerant spacecraft during autonomous approach to a single client in Low Earth Orbit.

Software for Engineering Simulations of a Spacecraft

Science.gov (United States)

Shireman, Kirk; McSwain, Gene; McCormick, Bernell; Fardelos, Panayiotis

2005-01-01

Spacecraft Engineering Simulation II (SES II) is a C-language computer program for simulating diverse aspects of operation of a spacecraft characterized by either three or six degrees of freedom. A functional model in SES can include a trajectory flight plan; a submodel of a flight computer running navigational and flight-control software; and submodels of the environment, the dynamics of the spacecraft, and sensor inputs and outputs. SES II features a modular, object-oriented programming style. SES II supports event-based simulations, which, in turn, create an easily adaptable simulation environment in which many different types of trajectories can be simulated by use of the same software. The simulation output consists largely of flight data. SES II can be used to perform optimization and Monte Carlo dispersion simulations. It can also be used to perform simulations for multiple spacecraft. In addition to its generic simulation capabilities, SES offers special capabilities for space-shuttle simulations: for this purpose, it incorporates submodels of the space-shuttle dynamics and a C-language version of the guidance, navigation, and control components of the space-shuttle flight software.

Environmentally-induced discharge transient coupling to spacecraft

Science.gov (United States)

Viswanathan, R.; Barbay, G.; Stevens, N. J.

1985-01-01

The Hughes SCREENS (Space Craft Response to Environments of Space) technique was applied to generic spin and 3-axis stabilized spacecraft models. It involved the NASCAP modeling for surface charging and lumped element modeling for transients coupling into a spacecraft. A differential voltage between antenna and spun shelf of approx. 400 V and current of 12 A resulted from discharge at antenna for the spinner and approx. 3 kv and 0.3 A from a discharge at solar panels for the 3-axis stabilized Spacecraft. A typical interface circuit response was analyzed to show that the transients would couple into the Spacecraft System through ground points, which are most vulnerable. A compilation and review was performed on 15 years of available data from electron and ion current collection phenomena. Empirical models were developed to match data and compared with flight data of Pix-1 and Pix-2 mission. It was found that large space power systems would float negative and discharge if operated at or above 300 V. Several recommendations are given to improve the models and to apply them to large space systems.

Effect of track etch rate on geometric track characteristics for polymeric track detectors

International Nuclear Information System (INIS)

Abdel-Naby, A.A.; El-Akkad, F.A.

2001-01-01

Analysis of the variable track etch rate on geometric track characteristic for polymeric track detectors has been applied to the case of LR-155 II SSNTD. Spectrometric characteristics of low energy alpha particles response by the polymeric detector have been obtained. The track etching kinematics theory of development of minor diameter of the etched tracks has been applied. The calculations show that, for this type of detector, the energy dependence of the minor track diameter d is linear for small-etched removal layer h. The energy resolution gets better for higher etched removal layer

Automated target recognition and tracking using an optical pattern recognition neural network

Science.gov (United States)

Chao, Tien-Hsin

1991-01-01

The on-going development of an automatic target recognition and tracking system at the Jet Propulsion Laboratory is presented. This system is an optical pattern recognition neural network (OPRNN) that is an integration of an innovative optical parallel processor and a feature extraction based neural net training algorithm. The parallel optical processor provides high speed and vast parallelism as well as full shift invariance. The neural network algorithm enables simultaneous discrimination of multiple noisy targets in spite of their scales, rotations, perspectives, and various deformations. This fully developed OPRNN system can be effectively utilized for the automated spacecraft recognition and tracking that will lead to success in the Automated Rendezvous and Capture (AR&C) of the unmanned Cargo Transfer Vehicle (CTV). One of the most powerful optical parallel processors for automatic target recognition is the multichannel correlator. With the inherent advantages of parallel processing capability and shift invariance, multiple objects can be simultaneously recognized and tracked using this multichannel correlator. This target tracking capability can be greatly enhanced by utilizing a powerful feature extraction based neural network training algorithm such as the neocognitron. The OPRNN, currently under investigation at JPL, is constructed with an optical multichannel correlator where holographic filters have been prepared using the neocognitron training algorithm. The computation speed of the neocognitron-type OPRNN is up to 10(exp 14) analog connections/sec that enabling the OPRNN to outperform its state-of-the-art electronics counterpart by at least two orders of magnitude.

High Accuracy Ground-based near-Earth-asteroid Astrometry using Synthetic Tracking

Science.gov (United States)

Zhai, Chengxing; Shao, Michael; Saini, Navtej; Sandhu, Jagmit; Werne, Thomas; Choi, Philip; Ely, Todd A.; Jacobs, Chirstopher S.; Lazio, Joseph; Martin-Mur, Tomas J.; Owen, William M.; Preston, Robert; Turyshev, Slava; Michell, Adam; Nazli, Kutay; Cui, Isaac; Monchama, Rachel

2018-01-01

Accurate astrometry is crucial for determining the orbits of near-Earth-asteroids (NEAs). Further, the future of deep space high data rate communications is likely to be optical communications, such as the Deep Space Optical Communications package that is part of the baseline payload for the planned Psyche Discovery mission to the Psyche asteroid. We have recently upgraded our instrument on the Pomona College 1 m telescope, at JPL's Table Mountain Facility, for conducting synthetic tracking by taking many short exposure images. These images can be then combined in post-processing to track both asteroid and reference stars to yield accurate astrometry. Utilizing the precision of the current and future Gaia data releases, the JPL-Pomona College effort is now demonstrating precision astrometry on NEAs, which is likely to be of considerable value for cataloging NEAs. Further, treating NEAs as proxies of future spacecraft that carry optical communication lasers, our results serve as a measure of the astrometric accuracy that could be achieved for future plane-of-sky optical navigation.

Testing of an End-Point Control Unit Designed to Enable Precision Control of Manipulator-Coupled Spacecraft

Science.gov (United States)

Montgomery, Raymond C.; Ghosh, Dave; Tobbe, Patrick A.; Weathers, John M.; Manouchehri, Davoud; Lindsay, Thomas S.

1994-01-01

This paper presents an end-point control concept designed to enable precision telerobotic control of manipulator-coupled spacecraft. The concept employs a hardware unit (end-point control unit EPCU) that is positioned between the end-effector of the Space Shuttle Remote Manipulator System and the payload. Features of the unit are active compliance (control of the displacement between the end-effector and the payload), to allow precision control of payload motions, and inertial load relief, to prevent the transmission of loads between the end-effector and the payload. This paper presents the concept and studies the active compliance feature using a simulation and hardware. Results of the simulation show the effectiveness of the EPCU in smoothing the motion of the payload. Results are presented from initial, limited tests of a laboratory hardware unit on a robotic arm testbed at the l Space Flight Center. Tracking performance of the arm in a constant speed automated retraction and extension maneuver of a heavy payload with and without the unit active is compared for the design speed and higher speeds. Simultaneous load reduction and tracking performance are demonstrated using the EPCU.

Application of the NASCAP Spacecraft Simulation Tool to Investigate Electrodynamic Tether Current Collection in LEO

Science.gov (United States)

Adams, Mitzi; HabashKrause, Linda

2012-01-01

Recent interest in using electrodynamic tethers (EDTs) for orbital maneuvering in Low Earth Orbit (LEO) has prompted the development of the Marshall ElectroDynamic Tether Orbit Propagator (MEDTOP) model. The model is comprised of several modules which address various aspects of EDT propulsion, including calculation of state vectors using a standard orbit propagator (e.g., J2), an atmospheric drag model, realistic ionospheric and magnetic field models, space weather effects, and tether librations. The natural electromotive force (EMF) attained during a radially-aligned conductive tether results in electrons flowing down the tether and accumulating on the lower-altitude spacecraft. The energy that drives this EMF is sourced from the orbital energy of the system; thus, EDTs are often proposed as de-orbiting systems. However, when the current is reversed using satellite charged particle sources, then propulsion is possible. One of the most difficult challenges of the modeling effort is to ascertain the equivalent circuit between the spacecraft and the ionospheric plasma. The present study investigates the use of the NASA Charging Analyzer Program (NASCAP) to calculate currents to and from the tethered satellites and the ionospheric plasma. NASCAP is a sophisticated set of computational tools to model the surface charging of three-dimensional (3D) spacecraft surfaces in a time-varying space environment. The model's surface is tessellated into a collection of facets, and NASCAP calculates currents and potentials for each one. Additionally, NASCAP provides for the construction of one or more nested grids to calculate space potential and time-varying electric fields. This provides for the capability to track individual particles orbits, to model charged particle wakes, and to incorporate external charged particle sources. With this study, we have developed a model of calculating currents incident onto an electrodynamic tethered satellite system, and first results are shown

Telemetry Timing Analysis for Image Reconstruction of Kompsat Spacecraft

Directory of Open Access Journals (Sweden)

Jin-Ho Lee

2000-06-01

Full Text Available The KOMPSAT (KOrea Multi-Purpose SATellite has two optical imaging instruments called EOC (Electro-Optical Camera and OSMI (Ocean Scanning Multispectral Imager. The image data of these instruments are transmitted to ground station and restored correctly after post-processing with the telemetry data transferred from KOMPSAT spacecraft. The major timing information of the KOMPSAT is OBT (On-Board Time which is formatted by the on-board computer of the spacecraft, based on 1Hz sync. pulse coming from the GPS receiver involved. The OBT is transmitted to ground station with the house-keeping telemetry data of the spacecraft while it is distributed to the instruments via 1553B data bus for synchronization during imaging and formatting. The timing information contained in the spacecraft telemetry data would have direct relation to the image data of the instruments, which should be well explained to get a more accurate image. This paper addresses the timing analysis of the KOMPSAT spacecraft and instruments, including the gyro data timing analysis for the correct restoration of the EOC and OSMI image data at ground station.

RFP to work on formation flying capabilities for spacecrafts for the GRACE project

DEFF Research Database (Denmark)

Riis, Troels; Thuesen, Gøsta; Kilsgaard, Søren

1999-01-01

The National Aeronautics and Space Agency of USA, NASA, are working on formation flying capabilities for spacecrafts, GRACE Project. IAU and JPL are developing the inter spacecraft attitude link to be used on the two spacecrafts.......The National Aeronautics and Space Agency of USA, NASA, are working on formation flying capabilities for spacecrafts, GRACE Project. IAU and JPL are developing the inter spacecraft attitude link to be used on the two spacecrafts....

Characterization of dust aggregates in the vicinity of the Rosetta spacecraft

Science.gov (United States)

Güttler, C.; Hasselmann, P. H.; Li, Y.; Fulle, M.; Tubiana, C.; Kovacs, G.; Agarwal, J.; Sierks, H.; Fornasier, S.; Hofmann, M.; Gutiérrez Marqués, P.; Ott, T.; Drolshagen, E.; Bertini, I.; Osiris Team

2017-09-01

In a Rosetta/OSIRIS imaging activity in June 2015, we have observed the dynamic motion of particles close to the spacecraft. Due to the focal setting of the OSIRIS Wide Angle Camera (WAC), these particles were blurred, which can be used to measure their distances to the spacecraft. We detected 108 dust aggregates over a 130 minutes long sequence, and find that their sizes are around a millimetre and their distances cluster between 2 m and 40 m from the spacecraft. Their number densities are about a factor 10 higher than expected for the overall coma and highly fluctuating. Their velocities are small compared to the spacecraft orbital motion and directed away from the spacecraft, towards the comet. From this we conclude that they have interacted with the spacecraft and assess three possible scenarios. We prefer a scenario where centimeter-sized aggregates collide with the spacecraft and we would observe the fragments. Ablation of a dust layer on the spacecraft's z panel when rotated towards the sun is a reasonable alternative. We could also measure an acceleration for a subset of 18 aggregates, which is directed away from the sun and can be explain by a rocket effect, which requires a minimum ice fraction in the order of 0.1%

Spacecraft charging: incoming and outgoing electrons

CERN Document Server

Lai, Shu T.

2013-04-22

This paper presents an overview of the roles played by incoming and outgoing electrons in spacecraft surface and stresses the importance of surface conditions for spacecraft charging. The balance between the incoming electron current from the ambient plasma and the outgoing currents of secondary electrons, backscattered electrons, and photoelectrons from the surfaces determines the surface potential. Since surface conditions significantly affect the outgoing currents, the critical temperature and the surface potential are also significantly affected. As a corollary, high level differential charging of adjacent surfaces with very different surface conditions is a space hazard.

Robust Parametric Control of Spacecraft Rendezvous

Directory of Open Access Journals (Sweden)

Dake Gu

2014-01-01

Full Text Available This paper proposes a method to design the robust parametric control for autonomous rendezvous of spacecrafts with the inertial information with uncertainty. We consider model uncertainty of traditional C-W equation to formulate the dynamic model of the relative motion. Based on eigenstructure assignment and model reference theory, a concise control law for spacecraft rendezvous is proposed which could be fixed through solving an optimization problem. The cost function considers the stabilization of the system and other performances. Simulation results illustrate the robustness and effectiveness of the proposed control.

Worldwide Spacecraft Crew Hatch History

Science.gov (United States)

Johnson, Gary

2009-01-01

The JSC Flight Safety Office has developed this compilation of historical information on spacecraft crew hatches to assist the Safety Tech Authority in the evaluation and analysis of worldwide spacecraft crew hatch design and performance. The document is prepared by SAIC s Gary Johnson, former NASA JSC S&MA Associate Director for Technical. Mr. Johnson s previous experience brings expert knowledge to assess the relevancy of data presented. He has experience with six (6) of the NASA spacecraft programs that are covered in this document: Apollo; Skylab; Apollo Soyuz Test Project (ASTP), Space Shuttle, ISS and the Shuttle/Mir Program. Mr. Johnson is also intimately familiar with the JSC Design and Procedures Standard, JPR 8080.5, having been one of its original developers. The observations and findings are presented first by country and organized within each country section by program in chronological order of emergence. A host of reference sources used to augment the personal observations and comments of the author are named within the text and/or listed in the reference section of this document. Careful attention to the selection and inclusion of photos, drawings and diagrams is used to give visual association and clarity to the topic areas examined.

A user's guide to the Flexible Spacecraft Dynamics and Control Program

Science.gov (United States)

Fedor, J. V.

1984-01-01

A guide to the use of the Flexible Spacecraft Dynamics Program (FSD) is presented covering input requirements, control words, orbit generation, spacecraft description and simulation options, and output definition. The program can be used in dynamics and control analysis as well as in orbit support of deployment and control of spacecraft. The program is applicable to inertially oriented spinning, Earth oriented or gravity gradient stabilized spacecraft. Internal and external environmental effects can be simulated.

Formation of disintegration particles in spacecraft recorders

International Nuclear Information System (INIS)

Kurnosova, L.V.; Fradkin, M.I.; Razorenov, L.A.

1986-01-01

Experiments performed on the spacecraft Salyut 1, Kosmos 410, and Kosmos 443 enable us to record the disintegration products of particles which are formed in the material of the detectors on board the spacecraft. The observations were made by means of a delayed coincidence method. We have detected a meson component and also a component which is apparently associated with the generation of radioactive isotopes in the detectors

Preliminary thermal design of the COLD-SAT spacecraft

Science.gov (United States)

Arif, Hugh

1991-01-01

The COLD-SAT free-flying spacecraft was to perform experiments with LH2 in the cryogenic fluid management technologies of storage, supply and transfer in reduced gravity. The Phase A preliminary design of the Thermal Control Subsystem (TCS) for the spacecraft exterior and interior surfaces and components of the bus subsystems is described. The TCS was composed of passive elements which were augmented with heaters. Trade studies to minimize the parasitic heat leakage into the cryogen storage tanks are described. Selection procedure for the thermally optimum on-orbit spacecraft attitude was defined. TRASYS-2 and SINDA'85 verification analysis was performed on the design and the results are presented.

Spacecraft charging and related effects during Halley encounter

International Nuclear Information System (INIS)

Young, D.T.

1983-01-01

Hypervelocity (69 km/s) impact of cometary material with surfaces of the GIOTTO spacecraft will induce a number of spurious and possibly harmful phenomena. The most serious of these is likely to be spacecraft charging that results from impact-produced plasma distributions surrounding GIOTTO. The ESA Plasma Environment Working Group, whose studies are the basis for this report, finds that charging may become significant within approx. 10 5 km of the nucleus where potentials of approx. = +20 V are to be expected. In addition to spacecraft charging, impact produced plasma may interfere with in situ plasma measurements, particularly those of ion plasma analyzers and mass spectrometers

The first collection of spacecraft-associated microorganisms: a public source for extremotolerant microorganisms from spacecraft assembly clean rooms.

Science.gov (United States)

Moissl-Eichinger, Christine; Rettberg, Petra; Pukall, Rüdiger

2012-11-01

For several reasons, spacecraft are constructed in so-called clean rooms. Particles could affect the function of spacecraft instruments, and for missions under planetary protection limitations, the biological contamination has to be restricted as much as possible. The proper maintenance of clean rooms includes, for instance, constant control of humidity and temperature, air filtering, and cleaning (disinfection) of the surfaces. The combination of these conditions creates an artificial, extreme biotope for microbial survival specialists: spore formers, autotrophs, multi-resistant, facultative, or even strictly anaerobic microorganisms have been detected in clean room habitats. Based on a diversity study of European and South-American spacecraft assembly clean rooms, the European Space Agency (ESA) has initialized and funded the creation of a public library of microbial isolates. Isolates from three different European clean rooms, as well as from the final assembly and launch facility in Kourou (French Guiana), have been phylogenetically analyzed and were lyophilized for long-term storage at the German Culture Collection facilities in Brunswick, Germany (Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen). The isolates were obtained by either following the standard protocol for the determination of bioburden on, and around, spacecraft or the use of alternative cultivation strategies. Currently, the database contains 298 bacterial strains. Fifty-nine strains are Gram-negative microorganisms, belonging to the α-, β- and γ-Proteobacteria. Representatives of the Gram-positive phyla Actinobacteria, Bacteroidetes/Chlorobi, and Firmicutes were subjected to the collection. Ninety-four isolates (21 different species) of the genus Bacillus were included in the ESA collection. This public collection of extremotolerant microbes, which are adapted to a complicated artificial biotope, provides a wonderful source for industry and research focused on

A novel adaptive sun tracker for spacecraft solar panel based on hybrid unsymmetric composite laminates

Science.gov (United States)

Wu, Zhangming; Li, Hao

2017-11-01

This paper proposes a novel adaptive sun tracker which is constructed by hybrid unsymmetric composite laminates. The adaptive sun tracker could be applied on spacecraft solar panels to increase their energy efficiency through decreasing the inclined angle between the sunlight and the solar panel normal. The sun tracker possesses a large rotation freedom and its rotation angle depends on the laminate temperature, which is affected by the light condition in the orbit. Both analytical model and finite element model (FEM) are developed for the sun tracker to predict its rotation angle in different light conditions. In this work, the light condition of the geosynchronous orbit on winter solstice is considered in the numerical prediction of the temperatures of the hybrid laminates. The final inclined angle between the sunlight and the solar panel normal during a solar day is computed using the finite element model. Parametric study of the adaptive sun tracker is conducted to improve its capacity and effectiveness of sun tracking. The improved adaptive sun tracker is lightweight and has a state-of-the-art design. In addition, the adaptive sun tracker does not consume any power of the solar panel, since it has no electrical driving devices. The proposed adaptive sun tracker provides a potential alternative to replace the traditional sophisticated electrical driving mechanisms for spacecraft solar panels.

Latent tracks in polymeric etched track detectors

International Nuclear Information System (INIS)

Yamauchi, Tomoya

2013-01-01

Track registration properties in polymeric track detectors, including Poly(allyl diglycol carbonate), Bispenol A polycarbonate, Poly(ethylen terephtarate), and Polyimide, have been investigated by means of Fourie transform Infararede FT-IR spectrometry. Chemical criterion on the track formation threshold has been proposes, in stead of the conventional physical track registration models. (author)

Quality of Slab Track Construction - Track Alignment Design and Track Geometry

Science.gov (United States)

Šestáková, Janka

2015-05-01

The slab track superstructure design (without ballast) is a perspective construction especially for building tunnels and bridges in the modernized sections of railway tracks in Slovakia. Monitoring of the structure described in this article is focused on the transition areas between standard structure with ballast and slab track construction.

Injection of an electron beam into a plasma and spacecraft charging

International Nuclear Information System (INIS)

Okuda, H.; Kan, J.R.

1987-01-01

Injection of a nonrelativistic electron beam into a fully ionized plasma from a spacecraft including the effect of charging has been studied using a one-dimensional particle simulation model. It is found that the spacecraft charging remains negligible and the beam can propagate into a plasma, if the beam density is much smaller than the ambient density. When the injection current is increased by increasing the beam density, significant spacecraft charging takes place and the reflection of beam electrons back to the spacecraft reduces the beam current significantly. On the other hand, if the injection current is increased by increasing the beam energy, spacecraft charging remains negligible and a beam current much larger than the thermal return current can be injected. It is shown that the electric field caused by the beam--plasma instability accelerates the ambient electrons toward the spacecraft thereby enhancing the return current

Enabling Advanced Automation in Spacecraft Operations with the Spacecraft Emergency Response System

Science.gov (United States)

Breed, Julie; Fox, Jeffrey A.; Powers, Edward I. (Technical Monitor)

2001-01-01

True autonomy is the Holy Grail of spacecraft mission operations. The goal of launching a satellite and letting it manage itself throughout its useful life is a worthy one. With true autonomy, the cost of mission operations would be reduced to a negligible amount. Under full autonomy, any problems (no matter the severity or type) that may arise with the spacecraft would be handled without any human intervention via some combination of smart sensors, on-board intelligence, and/or smart automated ground system. Until the day that complete autonomy is practical and affordable to deploy, incremental steps of deploying ever-increasing levels of automation (computerization of once manual tasks) on the ground and on the spacecraft are gradually decreasing the cost of mission operations. For example, NASA's Goddard Space Flight Center (NASA-GSFC) has been flying spacecraft with low cost operations for several years. NASA-GSFC's SMEX (Small Explorer) and MIDEX (Middle Explorer) missions have effectively deployed significant amounts of automation to enable the missions to fly predominately in 'light-out' mode. Under light-out operations the ground system is run without human intervention. Various tools perform many of the tasks previously performed by the human operators. One of the major issues in reducing human staff in favor of automation is the perceived increased in risk of losing data, or even losing a spacecraft, because of anomalous conditions that may occur when there is no one in the control center. When things go wrong, missions deploying advanced automation need to be sure that anomalous conditions are detected and that key personal are notified in a timely manner so that on-call team members can react to those conditions. To ensure the health and safety of its lights-out missions, NASA-GSFC's Advanced Automation and Autonomy branch (Code 588) developed the Spacecraft Emergency Response System (SERS). The SERS is a Web-based collaborative environment that enables

Probing interferometric parallax with interplanetary spacecraft

Science.gov (United States)

Rodeghiero, G.; Gini, F.; Marchili, N.; Jain, P.; Ralston, J. P.; Dallacasa, D.; Naletto, G.; Possenti, A.; Barbieri, C.; Franceschini, A.; Zampieri, L.

2017-07-01

We describe an experimental scenario for testing a novel method to measure distance and proper motion of astronomical sources. The method is based on multi-epoch observations of amplitude or intensity correlations between separate receiving systems. This technique is called Interferometric Parallax, and efficiently exploits phase information that has traditionally been overlooked. The test case we discuss combines amplitude correlations of signals from deep space interplanetary spacecraft with those from distant galactic and extragalactic radio sources with the goal of estimating the interplanetary spacecraft distance. Interferometric parallax relies on the detection of wavefront curvature effects in signals collected by pairs of separate receiving systems. The method shows promising potentialities over current techniques when the target is unresolved from the background reference sources. Developments in this field might lead to the construction of an independent, geometrical cosmic distance ladder using a dedicated project and future generation instruments. We present a conceptual overview supported by numerical estimates of its performances applied to a spacecraft orbiting the Solar System. Simulations support the feasibility of measurements with a simple and time-saving observational scheme using current facilities.

On-orbit supervisor for controlling spacecraft

Science.gov (United States)

Vandervoort, Richard J.

1992-07-01

Spacecraft systems of the 1990's and beyond will be substantially more complex than their predecessors. They will have demanding performance requirements and will be expected to operate more autonomously. This underscores the need for innovative approaches to Fault Detection, Isolation and Recovery (FDIR). A hierarchical expert system is presented that provides on-orbit supervision using intelligent FDIR techniques. Each expert system in the hierarchy supervises the operation of a local set of spacecraft functions. Spacecraft operational goals flow top down while responses flow bottom up. The expert system supervisors have a fairly high degree of autonomy. Bureaucratic responsibilities are minimized to conserve bandwidth and maximize response time. Data for FDIR can be acquired local to an expert and from other experts. By using a blackboard architecture for each supervisor, the system provides a great degree of flexibility in implementing the problem solvers for each problem domain. In addition, it provides for a clear separation between facts and knowledge, leading to an efficient system capable of real time response.

Microbiological sampling of spacecraft cabling, antennas, solar panels and thermal blankets

Science.gov (United States)

Koukol, R. C.

1973-01-01

Sampling procedures and techniques described resulted from various flight project microbiological monitoring programs of unmanned planetary spacecraft. Concurrent with development of these procedures, compatibility evaluations were effected with the cognizant spacecraft subsystem engineers to assure that degradation factors would not be induced during the monitoring program. Of significance were those areas of the spacecraft configuration for which special handling precautions and/or nonstandard sample gathering techniques were evolved. These spacecraft component areas were: cabling, high gain antenna, solar panels, and thermal blankets. The compilation of these techniques provides a historical reference for both the qualification and quantification of sampling parameters as applied to the Mariner Spacecraft of the late 1960's and early 1970's.

Cooper-Harper Experience Report for Spacecraft Handling Qualities Applications

Science.gov (United States)

Bailey, Randall E.; Jackson, E. Bruce; Bilimoria, Karl D.; Mueller, Eric R.; Frost, Chad R.; Alderete, Thomas S.

2009-01-01

A synopsis of experience from the fixed-wing and rotary-wing aircraft communities in handling qualities development and the use of the Cooper-Harper pilot rating scale is presented as background for spacecraft handling qualities research, development, test, and evaluation (RDT&E). In addition, handling qualities experiences and lessons-learned from previous United States (US) spacecraft developments are reviewed. This report is intended to provide a central location for references, best practices, and lessons-learned to guide current and future spacecraft handling qualities RDT&E.

Overview of SDCM - The Spacecraft Design and Cost Model

Science.gov (United States)

Ferebee, Melvin J.; Farmer, Jeffery T.; Andersen, Gregory C.; Flamm, Jeffery D.; Badi, Deborah M.

1988-01-01

The Spacecraft Design and Cost Model (SDCM) is a computer-aided design and analysis tool for synthesizing spacecraft configurations, integrating their subsystems, and generating information concerning on-orbit servicing and costs. SDCM uses a bottom-up method in which the cost and performance parameters for subsystem components are first calculated; the model then sums the contributions from individual components in order to obtain an estimate of sizes and costs for each candidate configuration within a selected spacecraft system. An optimum spacraft configuration can then be selected.

Historical Mass, Power, Schedule, and Cost Growth for NASA Spacecraft

Science.gov (United States)

Hayhurst, Marc R.; Bitten, Robert E.; Shinn, Stephen A.; Judnick, Daniel C.; Hallgrimson, Ingrid E.; Youngs, Megan A.

2016-01-01

Although spacecraft developers have been moving towards standardized product lines as the aerospace industry has matured, NASA's continual need to push the cutting edge of science to accomplish unique, challenging missions can still lead to spacecraft resource growth over time. This paper assesses historical mass, power, cost, and schedule growth for multiple NASA spacecraft from the last twenty years and compares to industry reserve guidelines to understand where the guidelines may fall short. Growth is assessed from project start to launch, from the time of the preliminary design review (PDR) to launch and from the time of the critical design review (CDR) to launch. Data is also assessed not just at the spacecraft bus level, but also at the subsystem level wherever possible, to help obtain further insight into possible drivers of growth. Potential recommendations to minimize spacecraft mass, power, cost, and schedule growth for future missions are also discussed.

Iterative Repair Planning for Spacecraft Operations Using the Aspen System

Science.gov (United States)

Rabideau, G.; Knight, R.; Chien, S.; Fukunaga, A.; Govindjee, A.

2000-01-01

This paper describes the Automated Scheduling and Planning Environment (ASPEN). ASPEN encodes complex spacecraft knowledge of operability constraints, flight rules, spacecraft hardware, science experiments and operations procedures to allow for automated generation of low level spacecraft sequences. Using a technique called iterative repair, ASPEN classifies constraint violations (i.e., conflicts) and attempts to repair each by performing a planning or scheduling operation. It must reason about which conflict to resolve first and what repair method to try for the given conflict. ASPEN is currently being utilized in the development of automated planner/scheduler systems for several spacecraft, including the UFO-1 naval communications satellite and the Citizen Explorer (CX1) satellite, as well as for planetary rover operations and antenna ground systems automation. This paper focuses on the algorithm and search strategies employed by ASPEN to resolve spacecraft operations constraints, as well as the data structures for representing these constraints.

A Quantized State Approach to On-line Simulation for Spacecraft Autonomy

DEFF Research Database (Denmark)

Alminde, Lars; Stoustrup, Jakob; Bendtsen, Jan Dimon

2006-01-01

Future space applications will require an increased level of operational autonomy. This calls for declarative methods for spacecraft state estimation and control, so that the spacecraft engineer can focus on modeling the spacecraft rather than implementing all details of the on-line system. Celeb...

A Reconfigurable Testbed Environment for Spacecraft Autonomy

Science.gov (United States)

Biesiadecki, Jeffrey; Jain, Abhinandan

1996-01-01

A key goal of NASA's New Millennium Program is the development of technology for increased spacecraft on-board autonomy. Achievement of this objective requires the development of a new class of ground-based automony testbeds that can enable the low-cost and rapid design, test, and integration of the spacecraft autonomy software. This paper describes the development of an Autonomy Testbed Environment (ATBE) for the NMP Deep Space I comet/asteroid rendezvous mission.

Spacecraft Hybrid (Mixed-Actuator) Attitude Control Experiences on NASA Science Missions

Science.gov (United States)

Dennehy, Cornelius J.

2014-01-01

There is a heightened interest within NASA for the design, development, and flight implementation of mixed-actuator hybrid attitude control systems for science spacecraft that have less than three functional reaction wheel actuators. This interest is driven by a number of recent reaction wheel failures on aging, but what could be still scientifically productive, NASA spacecraft if a successful hybrid attitude control mode can be implemented. Over the years, hybrid (mixed-actuator) control has been employed for contingency attitude control purposes on several NASA science mission spacecraft. This paper provides a historical perspective of NASA's previous engineering work on spacecraft mixed-actuator hybrid control approaches. An update of the current situation will also be provided emphasizing why NASA is now so interested in hybrid control. The results of the NASA Spacecraft Hybrid Attitude Control Workshop, held in April of 2013, will be highlighted. In particular, the lessons learned captured from that workshop will be shared in this paper. An update on the most recent experiences with hybrid control on the Kepler spacecraft will also be provided. This paper will close with some future considerations for hybrid spacecraft control.

The high energy multicharged particle exposure of the microbial ecology evaluation device on board the Apollo 16 spacecraft

Science.gov (United States)

Benton, E. V.; Henke, R. P.

1973-01-01

The high energy multicharged cosmic-ray-particle exposure of the Microbial Ecology Evaluation Device package on board the Apollo 16 spacecraft was monitored using cellulose nitrate, Lexan polycarbonate, nuclear emulsion, and silver chloride crystal nuclear-track detectors. The results of the analysis of these detectors include the measured particle fluences, the linear energy transfer spectra, and the integral atomic number spectrum of stopping particle density. The linear energy transfer spectrum is used to compute the fractional cell loss in human kidney (T1) cells caused by heavy particles. Because the Microbial Ecology Evaluation Device was better shielded, the high-energy multicharged particle exposure was less than that measured on the crew passive dosimeters.

Deep Space Networking Experiments on the EPOXI Spacecraft

Science.gov (United States)

Jones, Ross M.

2011-01-01

NASA's Space Communications & Navigation Program within the Space Operations Directorate is operating a program to develop and deploy Disruption Tolerant Networking [DTN] technology for a wide variety of mission types by the end of 2011. DTN is an enabling element of the Interplanetary Internet where terrestrial networking protocols are generally unsuitable because they rely on timely and continuous end-to-end delivery of data and acknowledgments. In fall of 2008 and 2009 and 2011 the Jet Propulsion Laboratory installed and tested essential elements of DTN technology on the Deep Impact spacecraft. These experiments, called Deep Impact Network Experiment (DINET 1) were performed in close cooperation with the EPOXI project which has responsibility for the spacecraft. The DINET 1 software was installed on the backup software partition on the backup flight computer for DINET 1. For DINET 1, the spacecraft was at a distance of about 15 million miles (24 million kilometers) from Earth. During DINET 1 300 images were transmitted from the JPL nodes to the spacecraft. Then, they were automatically forwarded from the spacecraft back to the JPL nodes, exercising DTN's bundle origination, transmission, acquisition, dynamic route computation, congestion control, prioritization, custody transfer, and automatic retransmission procedures, both on the spacecraft and on the ground, over a period of 27 days. The first DINET 1 experiment successfully validated many of the essential elements of the DTN protocols. DINET 2 demonstrated: 1) additional DTN functionality, 2) automated certain tasks which were manually implemented in DINET 1 and 3) installed the ION SW on nodes outside of JPL. DINET 3 plans to: 1) upgrade the LTP convergence-layer adapter to conform to the international LTP CL specification, 2) add convergence-layer "stewardship" procedures and 3) add the BSP security elements [PIB & PCB]. This paper describes the planning and execution of the flight experiment and the

A Shaftless Magnetically Levitated Multifunctional Spacecraft Flywheel Storage System

Science.gov (United States)

Stevens, Ken; Thornton, Richard; Clark, Tracy; Beaman, Bob G.; Dennehy, Neil; Day, John H. (Technical Monitor)

2002-01-01

Presently many types of spacecraft use a Spacecraft Attitude Control System (ACS) with momentum wheels for steering and electrochemical batteries to provide electrical power for the eclipse period of the spacecraft orbit. Future spacecraft will use Flywheels for combined use in ACS and Energy Storage. This can be done by using multiple wheels and varying the differential speed for ACS and varying the average speed for energy storage and recovery. Technology in these areas has improved since the 1990s so it is now feasible for flywheel systems to emerge from the laboratory for spacecraft use. This paper describes a new flywheel system that can be used for both ACS and energy storage. Some of the possible advantages of a flywheel system are: lower total mass and volume, higher efficiency, less thermal impact, improved satellite integration schedule and complexity, simplified satellite orbital operations, longer life with lower risk, less pointing jitter, and greater capability for high-rate slews. In short, they have the potential to enable new types of missions and provide lower cost. Two basic types of flywheel configurations are the Flywheel Energy Storage System (FESS) and the Integrated Power and Attitude Control System (IPACS).

Distributed Autonomous Control of Multiple Spacecraft During Close Proximity Operations

National Research Council Canada - National Science Library

McCamish, Shawn B

2007-01-01

This research contributes to multiple spacecraft control by developing an autonomous distributed control algorithm for close proximity operations of multiple spacecraft systems, including rendezvous...

Spacecraft Environmental Interactions Technology, 1983

Science.gov (United States)

1985-01-01

State of the art of environment interactions dealing with low-Earth-orbit plasmas; high-voltage systems; spacecraft charging; materials effects; and direction of future programs are contained in over 50 papers.

Spacecraft operations

CERN Document Server

Sellmaier, Florian; Schmidhuber, Michael

2015-01-01

The book describes the basic concepts of spaceflight operations, for both, human and unmanned missions. The basic subsystems of a space vehicle are explained in dedicated chapters, the relationship of spacecraft design and the very unique space environment are laid out. Flight dynamics are taught as well as ground segment requirements. Mission operations are divided into preparation including management aspects, execution and planning. Deep space missions and space robotic operations are included as special cases. The book is based on a course held at the German Space Operation Center (GSOC).

Event-triggered attitude control of spacecraft

Science.gov (United States)

Wu, Baolin; Shen, Qiang; Cao, Xibin

2018-02-01

The problem of spacecraft attitude stabilization control system with limited communication and external disturbances is investigated based on an event-triggered control scheme. In the proposed scheme, information of attitude and control torque only need to be transmitted at some discrete triggered times when a defined measurement error exceeds a state-dependent threshold. The proposed control scheme not only guarantees that spacecraft attitude control errors converge toward a small invariant set containing the origin, but also ensures that there is no accumulation of triggering instants. The performance of the proposed control scheme is demonstrated through numerical simulation.

Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior

Science.gov (United States)

Klem, B.; Swann, D.

2011-09-01

Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection

Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Facility Closing Report

Science.gov (United States)

Armstrong, J.; Martin, K. W.; Fraser, T.

2015-12-01

The Air Force Research Laboratory (AFRL) Spacecraft Component Thermal Research Group has been devoted to evaluating lifetime performance of space cryocooler technology for over twenty years. Long-life data is essential for confirming design lifetimes for space cryocoolers. Continuous operation in a simulated space environment is the only accepted method to test for degradation. AFRL has provided raw data and detailed evaluations to cryocooler developers for advancing the technology, correcting discovered deficiencies, and improving cryocooler designs. At AFRL, units of varying design and refrigeration cycles were instrumented in state-of-the-art experiment stands to provide spacelike conditions and were equipped with software data acquisition to track critical cryocooler operating parameters. This data allowed an assessment of the technology's ability to meet the desired lifetime and documented any long-term changes in performance. This paper will outline a final report of the various flight cryocoolers tested in our laboratory. The data summarized includes the seven cryocoolers tested during 2014-2015. These seven coolers have a combined total of 433,326 hours (49.5 years) of operation.

Fast-Acquisition/Weak-Signal-Tracking GPS Receiver for HEO

Science.gov (United States)

Wintemitz, Luke; Boegner, Greg; Sirotzky, Steve

2004-01-01

A report discusses the technical background and design of the Navigator Global Positioning System (GPS) receiver -- . a radiation-hardened receiver intended for use aboard spacecraft. Navigator is capable of weak signal acquisition and tracking as well as much faster acquisition of strong or weak signals with no a priori knowledge or external aiding. Weak-signal acquisition and tracking enables GPS use in high Earth orbits (HEO), and fast acquisition allows for the receiver to remain without power until needed in any orbit. Signal acquisition and signal tracking are, respectively, the processes of finding and demodulating a signal. Acquisition is the more computationally difficult process. Previous GPS receivers employ the method of sequentially searching the two-dimensional signal parameter space (code phase and Doppler). Navigator exploits properties of the Fourier transform in a massively parallel search for the GPS signal. This method results in far faster acquisition times [in the lab, 12 GPS satellites have been acquired with no a priori knowledge in a Low-Earth-Orbit (LEO) scenario in less than one second]. Modeling has shown that Navigator will be capable of acquiring signals down to 25 dB-Hz, appropriate for HEO missions. Navigator is built using the radiation-hardened ColdFire microprocessor and housing the most computationally intense functions in dedicated field-programmable gate arrays. The high performance of the algorithm and of the receiver as a whole are made possible by optimizing computational efficiency and carefully weighing tradeoffs among the sampling rate, data format, and data-path bit width.

Precise Relative Positioning of Formation Flying Spacecraft using GPS

NARCIS (Netherlands)

Kroes, R.

2006-01-01

Spacecraft formation flying is considered as a key technology for advanced space missions. Compared to large individual spacecraft, the distribution of sensor systems amongst multiple platforms offers improved flexibility, shorter times to mission, and the prospect of being more cost effective.

Embedded Thermal Control for Spacecraft Subsystems Miniaturization

Science.gov (United States)

Didion, Jeffrey R.

2014-01-01

Optimization of spacecraft size, weight and power (SWaP) resources is an explicit technical priority at Goddard Space Flight Center. Embedded Thermal Control Subsystems are a promising technology with many cross cutting NSAA, DoD and commercial applications: 1.) CubeSatSmallSat spacecraft architecture, 2.) high performance computing, 3.) On-board spacecraft electronics, 4.) Power electronics and RF arrays. The Embedded Thermal Control Subsystem technology development efforts focus on component, board and enclosure level devices that will ultimately include intelligent capabilities. The presentation will discuss electric, capillary and hybrid based hardware research and development efforts at Goddard Space Flight Center. The Embedded Thermal Control Subsystem development program consists of interrelated sub-initiatives, e.g., chip component level thermal control devices, self-sensing thermal management, advanced manufactured structures. This presentation includes technical status and progress on each of these investigations. Future sub-initiatives, technical milestones and program goals will be presented.

Definition of the topological structure of the automatic control system of spacecrafts

International Nuclear Information System (INIS)

KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F.Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Zelenkov, P V; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F.Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Karaseva, M V; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F.Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Tsareva, E A; Tsarev, R Y

2015-01-01

The paper considers the problem of selection the topological structure of the automated control system of spacecrafts. The integer linear model of mathematical programming designed to define the optimal topological structure for spacecraft control is proposed. To solve the determination problem of topological structure of the control system of spacecrafts developed the procedure of the directed search of some structure variants according to the scheme 'Branch and bound'. The example of the automated control system of spacecraft development included the combination of ground control stations, managing the spacecraft of three classes with a geosynchronous orbit with constant orbital periods is presented

A small spacecraft for multipoint measurement of ionospheric plasma

Science.gov (United States)

Roberts, T. M.; Lynch, K. A.; Clayton, R. E.; Weiss, J.; Hampton, D. L.

2017-07-01

Measurement of ionospheric plasma is often performed by a single in situ device or remotely using cameras and radar. This article describes a small, low-resource, deployed spacecraft used as part of a local, multipoint measurement network. A B-field aligned sounding rocket ejects four of these spin-stabilized spacecraft in a cross pattern. In this application, each spacecraft carries two retarding potential analyzers which are used to determine plasma density, flow, and ion temperature. An inertial measurement unit and a light-emitting diode array are used to determine the position and orientation of the devices after deployment. The design of this spacecraft is first described, and then results from a recent test flight are discussed. This flight demonstrated the successful operation of the deployment mechanism and telemetry systems, provided some preliminary plasma measurements in a simple mid-latitude environment, and revealed several design issues.

Spacecraft attitude determination using the earth's magnetic field

Science.gov (United States)

Simpson, David G.

1989-01-01

A method is presented by which the attitude of a low-Earth orbiting spacecraft may be determined using a vector magnetometer, a digital Sun sensor, and a mathematical model of the Earth's magnetic field. The method is currently being implemented for the Solar Maximum Mission spacecraft (as a backup for the failing star trackers) as a way to determine roll gyro drift.

Multiple spacecraft Michelson stellar interferometer

Science.gov (United States)

Stachnik, R. V.; Arnold, D.; Melroy, P.; Mccormack, E. F.; Gezari, D. Y.

1984-01-01

Results of an orbital analysis and performance assessment of SAMSI (Spacecraft Array for Michelson Spatial Interferometry) are presented. The device considered includes two one-meter telescopes in orbits which are identical except for slightly different inclinations; the telescopes achieve separations as large as 10 km and relay starlight to a central station which has a one-meter optical delay line in one interferometer arm. It is shown that a 1000-km altitude, zero mean inclination orbit affords natural scanning of the 10-km baseline with departures from optical pathlength equality which are well within the corrective capacity of the optical delay line. Electric propulsion is completely adequate to provide the required spacecraft motions, principally those needed for repointing. Resolution of 0.00001 arcsec and magnitude limits of 15 to 20 are achievable.

Effect of cross-correlation on track-to-track fusion

Science.gov (United States)

Saha, Rajat K.

1994-07-01

Since the advent of target tracking systems employing a diverse mixture of sensors, there has been increasing recognition by air defense system planners and other military system analysts of the need to integrate these tracks so that a clear air picture can be obtained in a command center. A popular methodology to achieve this goal is to perform track-to-track fusion, which performs track-to-track association as well as kinematic state vector fusion. This paper seeks to answer analytically the extent of improvement achievable by means of kinetic state vector fusion when the tracks are obtained from dissimilar sensors (e.g., Radar/ESM/IRST/IFF). It is well known that evaluation of the performance of state vector fusion algorithms at steady state must take into account the effects of cross-correlation between eligible tracks introduced by the input noise which, unfortunately, is often neglected because of added computational complexity. In this paper, an expression for the steady-state cross-covariance matrix for a 2D state vector track-to-track fusion is obtained. This matrix is shown to be a function of the parameters of the Kalman filters associated with the candidate tracks being fused. Conditions for positive definiteness of the cross-covariance matrix have been derived and the effect of positive definiteness on performance of track-to-track fusion is also discussed.

NucliTrack: an integrated nuclei tracking application.

Science.gov (United States)

Cooper, Sam; Barr, Alexis R; Glen, Robert; Bakal, Chris

2017-10-15

Live imaging studies give unparalleled insight into dynamic single cell behaviours and fate decisions. However, the challenge of reliably tracking single cells over long periods of time limits both the throughput and ease with which such studies can be performed. Here, we present NucliTrack, a cross platform solution for automatically segmenting, tracking and extracting features from fluorescently labelled nuclei. NucliTrack performs similarly to other state-of-the-art cell tracking algorithms, but NucliTrack's interactive, graphical interface makes it significantly more user friendly. NucliTrack is available as a free, cross platform application and open source Python package. Installation details and documentation are at: http://nuclitrack.readthedocs.io/en/latest/ A video guide can be viewed online: https://www.youtube.com/watch?v=J6e0D9F-qSU Source code is available through Github: https://github.com/samocooper/nuclitrack. A Matlab toolbox is also available at: https://uk.mathworks.com/matlabcentral/fileexchange/61479-samocooper-nuclitrack-matlab. sam@socooper.com. Supplementary data are available at Bioinformatics online. © The Author(s) 2017. Published by Oxford University Press.

A geometric model of a V-slit Sun sensor correcting for spacecraft wobble

Science.gov (United States)

Mcmartin, W. P.; Gambhir, S. S.

1994-01-01

A V-Slit sun sensor is body-mounted on a spin-stabilized spacecraft. During injection from a parking or transfer orbit to some final orbit, the spacecraft may not be dynamically balanced. This may result in wobble about the spacecraft spin axis as the spin axis may not be aligned with the spacecraft's axis of symmetry. While the widely used models in Spacecraft Attitude Determination and Control, edited by Wertz, correct for separation, elevation, and azimuthal mounting biases, spacecraft wobble is not taken into consideration. A geometric approach is used to develop a method for measurement of the sun angle which corrects for the magnitude and phase of spacecraft wobble. The algorithm was implemented using a set of standard mathematical routines for spherical geometry on a unit sphere.

Tracking and data system support for the Mariner Mars 1971 mission. Volume 3: Orbit insertion through end of primary mission

Science.gov (United States)

Barnum, P. W.; Renzetti, N. A.; Textor, G. P.; Kelly, L. B.

1973-01-01

The Tracking and Data System (TDS) Support for the Mariner Mars 1971 Mission final report contains the deep space tracking and data acquisition activities in support of orbital operations. During this period a major NASA objective was accomplished: completion of the 180th revolution and 90th day of data gathering with the spacecraft about the planet Mars. Included are presentations of the TDS flight support pass chronology data for each of the Deep Space Stations used, and performance evaluation for the Deep Space Network Telemetry, Tracking, Command, and Monitor Systems. With the loss of Mariner 8 at launch, Mariner 9 assumed the mission plan of Mariner 8, which included the TV mapping cycles and a 12-hr orbital period. The mission plan was modified as a result of a severe dust storm on the surface of Mars, which delayed the start of the TV mapping cycles. Thus, the end of primary mission date was extended to complete the TV mapping cycles.

SpaceX's Dragon America's next generation spacecraft

CERN Document Server

Seedhouse, Erik

2016-01-01

This book describes Dragon V2, a futuristic vehicle that not only provides a means for NASA to transport its astronauts to the orbiting outpost but also advances SpaceX’s core objective of reusability. A direct descendant of Dragon, Dragon V2 can be retrieved, refurbished and re-launched. It is a spacecraft with the potential to completely revolutionize the economics of an industry where equipment costing hundreds of millions of dollars is routinely discarded after a single use. It was presented by SpaceX CEO Elon Musk in May 2014 as the spaceship that will carry NASA astronauts to the International Space Station as soon as 2016 SpaceX’s Dragon – America’s Next Generation Spacecraft describes the extraordinary feats of engineering and human achievement that have placed this revolutionary spacecraft at the forefront of the launch industry and positioned it as the precursor for ultimately transporting humans to Mars. It describes the design and development of Dragon, provides mission highlights of the f...

Quality of Slab Track Construction – Track Alignment Design and Track Geometry

Directory of Open Access Journals (Sweden)

Šestáková Janka

2015-05-01

Full Text Available The slab track superstructure design (without ballast is a perspective construction especially for building tunnels and bridges in the modernized sections of railway tracks in Slovakia. Monitoring of the structure described in this article is focused on the transition areas between standard structure with ballast and slab track construction.

Autonomous spacecraft landing through human pre-attentive vision

International Nuclear Information System (INIS)

Schiavone, Giuseppina; Izzo, Dario; Simões, Luís F; De Croon, Guido C H E

2012-01-01

In this work, we exploit a computational model of human pre-attentive vision to guide the descent of a spacecraft on extraterrestrial bodies. Providing the spacecraft with high degrees of autonomy is a challenge for future space missions. Up to present, major effort in this research field has been concentrated in hazard avoidance algorithms and landmark detection, often by reference to a priori maps, ranked by scientists according to specific scientific criteria. Here, we present a bio-inspired approach based on the human ability to quickly select intrinsically salient targets in the visual scene; this ability is fundamental for fast decision-making processes in unpredictable and unknown circumstances. The proposed system integrates a simple model of the spacecraft and optimality principles which guarantee minimum fuel consumption during the landing procedure; detected salient sites are used for retargeting the spacecraft trajectory, under safety and reachability conditions. We compare the decisions taken by the proposed algorithm with that of a number of human subjects tested under the same conditions. Our results show how the developed algorithm is indistinguishable from the human subjects with respect to areas, occurrence and timing of the retargeting. (paper)

Coordinated Analyses of Diverse Components in Whole Stardust Cometary Tracks

Science.gov (United States)

Nakamura-Messenger, K.; Keller, L. P.; Messenger, S. R.; Clemett, S. J.; Nguyen, L. N.; Frank, D.

2011-12-01

Analyses of samples returned from Comet 81P/Wild-2 by the Stardust spacecraft have resulted in a number of surprising findings that show the origins of comets are more complex than previously suspected. However, these samples pose new experimental challenges because they are diverse and suffered fragmentation, thermal alteration, and fine scale mixing with aerogel. Questions remain about the nature of Wild-2 materials, such as the abundances of organic matter, crystalline materials, and presolar grains. To overcome these challenges, we have developed new sample preparation and analytical techniques tailored for entire aerogel tracks [Nakamura-Messenger et al. 2011]. We have successfully ultramicrotomed entire "carrot" and "bulbous" type tracks along their axis while preserving their original shapes. This innovation allowed us to examine the distribution of fragments along the track from the entrance hole all the way to the terminal particle (TP). We will present results of our coordinated analysis of the "carrot" type aerogel tracks #112 and #148, and the "bulbous" type aerogel tracks #113, #147 and #168 from the nanometer to the millimeter scale. Scanning TEM (STEM) was used for elemental and detailed mineralogy characterization, NanoSIMS was used for isotopic analyses, and ultrafast two-step laser mass spectrometry (ultra L2MS) was used to investigate the nature and distribution of organic phases. The isotopic measurements were performed following detailed TEM characterization for coordinated mineralogy. This approach also enabled spatially resolving the target sample from fine-scale mixtures of compressed aerogel and melt. Eight of the TPs of track #113 are dominated by coarse-grained enstatite (En90) that is largely orthoenstatite with minor, isolated clinoenstatite lamellae. One TP contains minor forsterite (Fo88) and small inclusions of diopside with % levels of Al, Cr and Fe. Two of the TPs contain angular regions of fine-grained nepheline surrounded by

Spacecraft on-orbit deployment anomalies - What can be done?

Science.gov (United States)

Freeman, Michael T.

1993-04-01

Modern communications satellites rely heavily upon deployable appendage (i.e. solar arrays, communications antennas, etc.) to perform vital functions that enable the spacecraft to effectively conduct mission objectives. Communications and telemetry antennas provide the radiofrequency link between the spacecraft and the earth ground station, permitting data to be transmitted and received from the satellite. Solar arrays serve as the principle source of electrical energy to the satellite, and recharge internal batteries during operation. However, since satellites cannot carry backup systems, if a solar array fails to deploy, the mission is lost. This article examines the subject of on-orbit anomalies related to the deployment of spacecraft appendage, and possible causes of such failures. Topics discussed shall include mechanical launch loading, on-orbit thermal and solar concerns, reliability of spacecraft pyrotechnics, and practical limitations of ground-based deployment testing. Of particular significance, the article will feature an in-depth look at the lessons learned from the successful recovery of the Telesat Canada Anik-E2 satellite in 1991.

Correlation of ICME Magnetic Fields at Radially Aligned Spacecraft

Science.gov (United States)

Good, S. W.; Forsyth, R. J.; Eastwood, J. P.; Möstl, C.

2018-03-01

The magnetic field structures of two interplanetary coronal mass ejections (ICMEs), each observed by a pair of spacecraft close to radial alignment, have been analysed. The ICMEs were observed in situ by MESSENGER and STEREO-B in November 2010 and November 2011, while the spacecraft were separated by more than 0.6 AU in heliocentric distance, less than 4° in heliographic longitude, and less than 7° in heliographic latitude. Both ICMEs took approximately two days to travel between the spacecraft. The ICME magnetic field profiles observed at MESSENGER have been mapped to the heliocentric distance of STEREO-B and compared directly to the profiles observed by STEREO-B. Figures that result from this mapping allow for easy qualitative assessment of similarity in the profiles. Macroscale features in the profiles that varied on timescales of one hour, and which corresponded to the underlying flux rope structure of the ICMEs, were well correlated in the solar east-west and north-south directed components, with Pearson's correlation coefficients of approximately 0.85 and 0.95, respectively; microscale features with timescales of one minute were uncorrelated. Overall correlation values in the profiles of one ICME were increased when an apparent change in the flux rope axis direction between the observing spacecraft was taken into account. The high degree of similarity seen in the magnetic field profiles may be interpreted in two ways. If the spacecraft sampled the same region of each ICME ( i.e. if the spacecraft angular separations are neglected), the similarity indicates that there was little evolution in the underlying structure of the sampled region during propagation. Alternatively, if the spacecraft observed different, nearby regions within the ICMEs, it indicates that there was spatial homogeneity across those different regions. The field structure similarity observed in these ICMEs points to the value of placing in situ space weather monitors well upstream of the

Rockets and spacecraft: Sine qua non of space science

Science.gov (United States)

1980-01-01

The evolution of the national launch vehicle stable is presented along with lists of launch vehicles used in NASA programs. A partial list of spacecraft used throughout the world is also given. Scientific spacecraft costs are presented along with an historial overview of project development and funding in NASA.

Multiple spacecraft configuration designs for coordinated flight missions

Science.gov (United States)

Fumenti, Federico; Theil, Stephan

2018-06-01

Coordinated flight allows the replacement of a single monolithic spacecraft with multiple smaller ones, based on the principle of distributed systems. According to the mission objectives and to ensure a safe relative motion, constraints on the relative distances need to be satisfied. Initially, differential perturbations are limited by proper orbit design. Then, the induced differential drifts can be properly handled through corrective maneuvers. In this work, several designs are surveyed, defining the initial configuration of a group of spacecraft while counteracting the differential perturbations. For each of the investigated designs, focus is placed upon the number of deployable spacecraft and on the possibility to ensure safe relative motion through station keeping of the initial configuration, with particular attention to the required Δ V budget and the constraints violations.

Operationally Responsive Spacecraft Subsystem, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Saber Astronautics proposes spacecraft subsystem control software which can autonomously reconfigure avionics for best performance during various mission conditions....

Conceptual definition of Automated Power Systems Management. [for planetary spacecraft

Science.gov (United States)

Imamura, M. S.; Skelly, L.; Weiner, H.

1977-01-01

Automated Power Systems Management (APSM) is defined as the capability of a spacecraft power system to automatically perform monitoring, computational, command, and control functions without ground intervention. Power systems for future planetary spacecraft must have this capability because they must perform up to 10 years, and accommodate real-time changes in mission execution autonomously. Specific APSM functions include fault detection, isolation, and correction; system performance and load profile prediction; power system optimization; system checkout; and data storage and transmission control. This paper describes the basic method of implementing these specific functions. The APSM hardware includes a central power system computer and a processor dedicated to each major power system subassembly along with digital interface circuitry. The major payoffs anticipated are in enhancement of spacecraft reliability and life and reduction of overall spacecraft program cost.

Ad hoc laser networks component technology for modular spacecraft

Science.gov (United States)

Huang, Xiujun; Shi, Dele; Shen, Jingshi

2017-10-01

Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

Comprehensive Fault Tolerance and Science-Optimal Attitude Planning for Spacecraft Applications

Science.gov (United States)

Nasir, Ali

Spacecraft operate in a harsh environment, are costly to launch, and experience unavoidable communication delay and bandwidth constraints. These factors motivate the need for effective onboard mission and fault management. This dissertation presents an integrated framework to optimize science goal achievement while identifying and managing encountered faults. Goal-related tasks are defined by pointing the spacecraft instrumentation toward distant targets of scientific interest. The relative value of science data collection is traded with risk of failures to determine an optimal policy for mission execution. Our major innovation in fault detection and reconfiguration is to incorporate fault information obtained from two types of spacecraft models: one based on the dynamics of the spacecraft and the second based on the internal composition of the spacecraft. For fault reconfiguration, we consider possible changes in both dynamics-based control law configuration and the composition-based switching configuration. We formulate our problem as a stochastic sequential decision problem or Markov Decision Process (MDP). To avoid the computational complexity involved in a fully-integrated MDP, we decompose our problem into multiple MDPs. These MDPs include planning MDPs for different fault scenarios, a fault detection MDP based on a logic-based model of spacecraft component and system functionality, an MDP for resolving conflicts between fault information from the logic-based model and the dynamics-based spacecraft models" and the reconfiguration MDP that generates a policy optimized over the relative importance of the mission objectives versus spacecraft safety. Approximate Dynamic Programming (ADP) methods for the decomposition of the planning and fault detection MDPs are applied. To show the performance of the MDP-based frameworks and ADP methods, a suite of spacecraft attitude planning case studies are described. These case studies are used to analyze the content and

DOD Recovery personnel and NASA technicians inspect Friendship 7 spacecraft

Science.gov (United States)

1964-01-01

Department of Defense Recovery personnel and spacecraft technicians from NASA adn McDonnell Aircraft Corp., inspect Astronaut John Glenn's Mercury spacecraft, Friendship 7, following its return to Cape Canaveral after recovery in the Atlantic Ocean.

A Study of Learning Curve Impact on Three Identical Small Spacecraft

Science.gov (United States)

Chen, Guangming; McLennan, Douglas D.

2003-01-01

With an eye to the future strategic needs of NASA, the New Millennium Program is funding the Space Technology 5 (ST-5) project to address the future needs in the area of small satellites in constellation missions. The ST-5 project, being developed at Goddard Space Flight Center, involves the development and simultaneous launch of three small, 20-kilogram-class spacecraft. ST-5 is only a test drive and future NASA science missions may call for fleets of spacecraft containing tens of smart and capable satellites in an intelligent constellation. The objective of ST-5 project is to develop three such pioneering small spacecraft for flight validation of several critical new technologies. The ST-5 project team at Goddard Space Flight Center has completed the spacecraft design, is now building and testing the three flight units. The launch readiness date (LRD) is in December 2005. A critical part of ST-5 mission is to prove that it is possible to build these small but capable spacecraft with recurring cost low enough to make future NASA s multi- spacecraft constellation missions viable from a cost standpoint.

Nanoscale measurements of proton tracks using fluorescent nuclear track detectors

Energy Technology Data Exchange (ETDEWEB)

Sawakuchi, Gabriel O., E-mail: gsawakuchi@mdanderson.org; Sahoo, Narayan [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas 77030 (United States); Ferreira, Felisberto A. [Department of Nuclear Physics, University of Sao Paulo, SP 05508-090 (Brazil); McFadden, Conor H. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Hallacy, Timothy M. [Biophysics Program, Harvard University, Cambridge, Massachusetts 02138 (United States); Granville, Dal A. [Department of Medical Physics, The Ottawa Hospital Cancer Centre, Ottawa, Ontario K1H 8L6 (Canada); Akselrod, Mark S. [Crystal Growth Division, Landauer, Inc., Stillwater, Oklahoma 74074 (United States)

2016-05-15

Purpose: The authors describe a method in which fluorescence nuclear track detectors (FNTDs), novel track detectors with nanoscale spatial resolution, are used to determine the linear energy transfer (LET) of individual proton tracks from proton therapy beams by allowing visualization and 3D reconstruction of such tracks. Methods: FNTDs were exposed to proton therapy beams with nominal energies ranging from 100 to 250 MeV. Proton track images were then recorded by confocal microscopy of the FNTDs. Proton tracks in the FNTD images were fit by using a Gaussian function to extract fluorescence amplitudes. Histograms of fluorescence amplitudes were then compared with LET spectra. Results: The authors successfully used FNTDs to register individual proton tracks from high-energy proton therapy beams, allowing reconstruction of 3D images of proton tracks along with delta rays. The track amplitudes from FNTDs could be used to parameterize LET spectra, allowing the LET of individual proton tracks from therapeutic proton beams to be determined. Conclusions: FNTDs can be used to directly visualize proton tracks and their delta rays at the nanoscale level. Because the track intensities in the FNTDs correlate with LET, they could be used further to measure LET of individual proton tracks. This method may be useful for measuring nanoscale radiation quantities and for measuring the LET of individual proton tracks in radiation biology experiments.

The Stardust spacecraft arrives at KSC

Science.gov (United States)

1998-01-01

After arrival at the Shuttle Landing Facility in the early morning hours, the crated Stardust spacecraft waits to be unloaded from the aircraft. Built by Lockheed Martin Astronautics near Denver, Colo., for the Jet Propulsion Laboratory (JPL) NASA, the spacecraft Stardust will use a unique medium called aerogel to capture comet particles flying off the nucleus of comet Wild 2 in January 2004, plus collect interstellar dust for later analysis. Stardust will be launched aboard a Boeing Delta 7426 rocket from Complex 17, Cape Canaveral Air Station, targeted for Feb. 6, 1999. The collected samples will return to Earth in a re- entry capsule to be jettisoned from Stardust as it swings by in January 2006.

Improved techniques for predicting spacecraft power

International Nuclear Information System (INIS)

Chmielewski, A.B.

1987-01-01

Radioisotope Thermoelectric Generators (RTGs) are going to supply power for the NASA Galileo and Ulysses spacecraft now scheduled to be launched in 1989 and 1990. The duration of the Galileo mission is expected to be over 8 years. This brings the total RTG lifetime to 13 years. In 13 years, the RTG power drops more than 20 percent leaving a very small power margin over what is consumed by the spacecraft. Thus it is very important to accurately predict the RTG performance and be able to assess the magnitude of errors involved. The paper lists all the error sources involved in the RTG power predictions and describes a statistical method for calculating the tolerance

Large Scale Experiments on Spacecraft Fire Safety

Science.gov (United States)

Urban, David; Ruff, Gary A.; Minster, Olivier; Fernandez-Pello, A. Carlos; Tien, James S.; Torero, Jose L.; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu;

Propulsion Trade Studies for Spacecraft Swarm Mission Design

Science.gov (United States)

Dono, Andres; Plice, Laura; Mueting, Joel; Conn, Tracie; Ho, Michael

2018-01-01

Spacecraft swarms constitute a challenge from an orbital mechanics standpoint. Traditional mission design involves the application of methodical processes where predefined maneuvers for an individual spacecraft are planned in advance. This approach does not scale to spacecraft swarms consisting of many satellites orbiting in close proximity; non-deterministic maneuvers cannot be preplanned due to the large number of units and the uncertainties associated with their differential deployment and orbital motion. For autonomous small sat swarms in LEO, we investigate two approaches for controlling the relative motion of a swarm. The first method involves modified miniature phasing maneuvers, where maneuvers are prescribed that cancel the differential delta V of each CubeSat's deployment vector. The second method relies on artificial potential functions (APFs) to contain the spacecraft within a volumetric boundary and avoid collisions. Performance results and required delta V budgets are summarized, indicating that each method has advantages and drawbacks for particular applications. The mini phasing maneuvers are more predictable and sustainable. The APF approach provides a more responsive and distributed performance, but at considerable propellant cost. After considering current state of the art CubeSat propulsion systems, we conclude that the first approach is feasible, but the modified APF method of requires too much control authority to be enabled by current propulsion systems.

Video-Game-Like Engine for Depicting Spacecraft Trajectories

Science.gov (United States)

Upchurch, Paul R.

2009-01-01

GoView is a video-game-like software engine, written in the C and C++ computing languages, that enables real-time, three-dimensional (3D)-appearing visual representation of spacecraft and trajectories (1) from any perspective; (2) at any spatial scale from spacecraft to Solar-system dimensions; (3) in user-selectable time scales; (4) in the past, present, and/or future; (5) with varying speeds; and (6) forward or backward in time. GoView constructs an interactive 3D world by use of spacecraft-mission data from pre-existing engineering software tools. GoView can also be used to produce distributable application programs for depicting NASA orbital missions on personal computers running the Windows XP, Mac OsX, and Linux operating systems. GoView enables seamless rendering of Cartesian coordinate spaces with programmable graphics hardware, whereas prior programs for depicting spacecraft trajectories variously require non-Cartesian coordinates and/or are not compatible with programmable hardware. GoView incorporates an algorithm for nonlinear interpolation between arbitrary reference frames, whereas the prior programs are restricted to special classes of inertial and non-inertial reference frames. Finally, whereas the prior programs present complex user interfaces requiring hours of training, the GoView interface provides guidance, enabling use without any training.

Attitude Dynamics and Tracking Control of Spacecraft in the Presence of Gravity Oblateness Perturbations

Directory of Open Access Journals (Sweden)

Achim IONITA

2016-03-01

Full Text Available The orbital docking represents a problem of great importance in aerospace engineering. The paper aims to perform an analysis of docking maneuvers between a chaser vehicle and a target vehicle in permanent LEO (low earth orbit. The work begins with a study of the attitude dynamics modeling intended to define the strategy that facilitates the chaser movement toward a docking part of the target. An LQR (linear quadratic regulator approach presents an optimal control design that provides linearized closed-loop error dynamics for tracking a desired quaternion. The control law formulation is combined with the control architecture based on SDRE (State Dependent Riccati equation technique for rotational maneuvers, including the Earth oblateness perturbation. The chaser body-fixed frame must coincide with the target body-fixed frame at the docking moment. Then the implementation of the control architecture based on LQR technique using the computational tool MATLAB is carried out. In simulation of the docking strategy V-R bar operations are analyzed and the minimum accelerations needs the control of chaser vehicle. The simulation analysis of those maneuvers considered for a chaser vehicle and a target vehicle in LEO orbit is validated in a case study.

Equations of Motion of Free-Floating Spacecraft-Manipulator Systems: An Engineer's Tutorial

Directory of Open Access Journals (Sweden)

Markus Wilde

2018-04-01

Full Text Available The paper provides a step-by-step tutorial on the Generalized Jacobian Matrix (GJM approach for modeling and simulation of spacecraft-manipulator systems. The General Jacobian Matrix approach describes the motion of the end-effector of an underactuated manipulator system solely by the manipulator joint rotations, with the attitude and position of the base-spacecraft resulting from the manipulator motion. The coupling of the manipulator motion with the base-spacecraft are thus expressed in a generalized inertia matrix and a GJM. The focus of the paper lies on the complete analytic derivation of the generalized equations of motion of a free-floating spacecraft-manipulator system. This includes symbolic analytic expressions for all inertia property matrices of the system, including their time derivatives and joint-angle derivatives, as well as an expression for the generalized Jacobian of a generic point on any link of the spacecraft-manipulator system. The kinematics structure of the spacecraft-manipulator system is described both in terms of direction-cosine matrices and unit quaternions. An additional important contribution of this paper is to propose a new and more detailed definition for the modes of maneuvering of a spacecraft-manipulator. In particular, the two commonly used categories free-flying and free-floating are expanded by the introduction of five categories, namely floating, rotation-floating, rotation-flying, translation-flying, and flying. A fully-symbolic and a partially-symbolic option for the implementation of a numerical simulation model based on the proposed analytic approach are introduced and exemplary simulation results for a planar four-link spacecraft-manipulator system and a spatial six-link spacecraft manipulator system are presented.

Tracking errors in a prototype real-time tumour tracking system

International Nuclear Information System (INIS)

Sharp, Gregory C; Jiang, Steve B; Shimizu, Shinichi; Shirato, Hiroki

2004-01-01

In motion-compensated radiation therapy, radio-opaque markers can be implanted in or near a tumour and tracked in real-time using fluoroscopic imaging. Tracking these implanted markers gives highly accurate position information, except when tracking fails due to poor or ambiguous imaging conditions. This study investigates methods for automatic detection of tracking errors, and assesses the frequency and impact of tracking errors on treatments using the prototype real-time tumour tracking system. We investigated four indicators for automatic detection of tracking errors, and found that the distance between corresponding rays was most effective. We also found that tracking errors cause a loss of gating efficiency of between 7.6 and 10.2%. The incidence of treatment beam delivery during tracking errors was estimated at between 0.8% and 1.25%

Spacecraft Charging Modeling -- Nascap-2k 2014 Annual Report

Science.gov (United States)

2014-09-19

appears to work similarly in Internet Explorer, FireFox , and Opera, but fails in Safari and Chrome. Note that the SEE Spacecraft Charging Handbook is... Characteristics of Spacecraft Charging in Low Earth Orbit, J Geophys Res. 11 7, doi: 10.1029/20 11JA016875, 2012. 2 M. Cho, K. Saito, T. Hamanaga, Data

Guidance, navigation, and control subsystem for the EOS-AM spacecraft

Science.gov (United States)

Linder, David M.; Tolek, Joseph T.; Lombardo, John

1992-01-01

This paper presents the preliminary design of the Guidance, Navigation, and Control (GN&C) subsystem for the EOS-AM spacecraft and specifically focuses on the GN&C Normal Mode design. First, a brief description of the EOS-AM science mission, instruments, and system-level spacecraft design is provided. Next, an overview of the GN&C subsystem functional and performance requirements, hardware, and operating modes is presented. Then, the GN&C Normal Mode attitude determination, attitude control, and navigation systems are detailed. Finally, descriptions of the spacecraft's overall jitter performance and Safe Mode are provided.

Problems associated with the investigation of the natural environment from manned spacecraft

Energy Technology Data Exchange (ETDEWEB)

Vinogradov, B V [Akademiia Nauk SSSR, Institut Okeanologii, Leningrad, USSR; Sevastianov, V I

1980-01-01

Recent Soviet research dealing with the remote sensing of the earth's surface from manned spacecraft is reviewed. Particular attention is given to visual observations, spectrophotometry, and monospectral and multispectral photography performed from the Soyuz and Salyut spacecraft. The use of spacecraft images in agriculture is emphasized economic factors are discussed.

Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

OpenAIRE

Li, Dong-Xu; Liu, Wang; Hao, Dong

2017-01-01

Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections b...

Spacecraft early design validation using formal methods

International Nuclear Information System (INIS)

Bozzano, Marco; Cimatti, Alessandro; Katoen, Joost-Pieter; Katsaros, Panagiotis; Mokos, Konstantinos; Nguyen, Viet Yen; Noll, Thomas; Postma, Bart; Roveri, Marco

2014-01-01

The size and complexity of software in spacecraft is increasing exponentially, and this trend complicates its validation within the context of the overall spacecraft system. Current validation methods are labor-intensive as they rely on manual analysis, review and inspection. For future space missions, we developed – with challenging requirements from the European space industry – a novel modeling language and toolset for a (semi-)automated validation approach. Our modeling language is a dialect of AADL and enables engineers to express the system, the software, and their reliability aspects. The COMPASS toolset utilizes state-of-the-art model checking techniques, both qualitative and probabilistic, for the analysis of requirements related to functional correctness, safety, dependability and performance. Several pilot projects have been performed by industry, with two of them having focused on the system-level of a satellite platform in development. Our efforts resulted in a significant advancement of validating spacecraft designs from several perspectives, using a single integrated system model. The associated technology readiness level increased from level 1 (basic concepts and ideas) to early level 4 (laboratory-tested)

Comparison of media for detection of fungi on spacecraft

Science.gov (United States)

Herring, C. M.; Brandsberg, J. W.; Oxborrow, G. S.; Puleo, J. R.

1974-01-01

Five media, including Trypticase soy agar (TSA; BBL) pour plates, spread plates of TSA, Mycophil agar with chloromycetin, Mycophil agar with chloromycetin and Actidione, and cornmeal agar with chloromycetin were quantitatively and qualitatively compared for the detection of fungi on spacecraft. Cornmeal agar with chloromycetin yielded the highest number of fungal colonies, although not always significantly higher than Mycophil agar with chloromycetin or TSA spread plates. Cornmeal agar with chloromycetin also gave the best qualitative representation of fungi on the spacecraft, recovering 68% of the genera found from all media. This medium yielded 10 times the number of fungal colonies and 3 times the number of genera found on TSA pour plates as currently used for spacecraft assay.

The Size of Mars' Fluid Core From Mars k2 Love Number Obtained From Analysis of MGS Doppler Tracking.

Science.gov (United States)

Yoder, C. F.; Konopliv, A. S.; Yuan, D. N.; Standish, E. M.; Folkner, W. M.

2002-12-01

The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from analysis of MGS radio tracking. The observed k2 =0.164+-0.016 is large enough to rule out a solid iron core. The inferred core radius Rc (1600kmspacecraft orbit inclination related to the sun-synchronous spacecraft orbit and which is seen only in the m=2 tide. In order to minimize the effect of along-track changes on a solution for k22, the drag model solves for a daily coefficient and thus effectively minimizes the influence of the along-track residual signature on this solution parameter. The k21 and k22 coefficients primarily affect the orbit node (k21 has an annual variation) where it is strongly mixed with seasonal changes in Mars' even zonal gravity harmonics (J2, J4). The odd gravity harmonics (J3, J5) are detected through seasonal changes in orbit eccentricity where the influences of tides are weak. The observed J3, J5 amplitudes are consistent with estimates of ice cap mass only if the cap thickness increases with latitude and the south cap is significantly larger than the north cap.

Thrusting maneuver control of a small spacecraft via only gimbaled-thruster scheme

Science.gov (United States)

Kabganian, Mansour; Kouhi, Hamed; Shahravi, Morteza; Fani Saberi, Farhad

2018-05-01

The thrust vector control (TVC) scheme is a powerful method in spacecraft attitude control. Since the control of a small spacecraft is being studied here, a solid rocket motor (SRM) should be used instead of a liquid propellant motor. Among the TVC methods, gimbaled-TVC as an efficient method is employed in this paper. The spacecraft structure is composed of a body and a gimbaled-SRM where common attitude control systems such as reaction control system (RCS) and spin-stabilization are not presented. A nonlinear two-body model is considered for the characterization of the gimbaled-thruster spacecraft where, the only control input is provided by a gimbal actuator. The attitude of the spacecraft is affected by a large exogenous disturbance torque which is generated by a thrust vector misalignment from the center of mass (C.M). A linear control law is designed to stabilize the spacecraft attitude while rejecting the mentioned disturbance torque. A semi-analytical formulation of the region of attraction (RoA) is developed to ensure the local stability and fast convergence of the nonlinear closed-loop system. Simulation results of the 3D maneuvers are included to show the applicability of this method for use in a small spacecraft.

The purpose for GEO spacecraft deep charging and electrostatic discharging (ESD) experiment

International Nuclear Information System (INIS)

Yang Chuibai; Wang Shijin; Liang Jinbao

2005-01-01

This paper introduces the purpose for GEO spacecraft deep charging and electrostatic discharging (ESD) experiment. A method of experiment for the spacecraft deep charging and ESD aboard is proposed. Spacecraft deep charging and ESD event, frequency, energy and the level of pulse in wires due to EMP coupling into are measured. (authors)

Positioning Reduction of Deep Space Probes Based on VLBI Tracking

Science.gov (United States)

Qiao, S. B.

2011-11-01

In the background of the Chinese Lunar Exploration Project and the Yinghuo Project, through theoretical analysis, algorithm study, software development, data simulation, real data processing and so on, the positioning reductions of the European lunar satellite Smart-1 and Mars Express (MEX) satellite, as well as the Chinese Chang'e-1 (CE-1) and Chang'e-2 (CE-2) satellites are accomplished by using VLBI and USB tracking data in this dissertation. The progress is made in various aspects including the development of theoretical model, the construction of observation equation, the analysis of the condition of normal equation, the selection and determination of the constraint, the analysis of data simulation, the detection of outliers in observations, the maintenance of the stability of the solution of parameters, the development of the practical software system, the processing of the real tracking data and so on. The details of the research progress in this dissertation are written as follows: (1) The algorithm is analyzed concerning the positioning reduction of the deep spacecraft based on VLBI tracking data. Through data simulation, it is analyzed for the effects of the bias in predicted orbit, the white noises and systematic errors in VLBI delays, and USB ranges on the positioning reduction of spacecraft. Results show that it is preferable to suppress the dispersion of positioning data points by applying the constraint of geocentric distance of spacecraft when there are only VLBI tracking data. The positioning solution is a biased estimate via observations of three VLBI stations. For the case of four tracking stations, the uncertainty of the constraint should be in accordance with the bias in the predicted orbit. White noises in delays and ranges mainly result in dispersion of the sequence of positioning data points. If there is the systematic error of observations, the systematic offset of the positioning results is caused, and there are trend jumps in the shape of

Parameter Estimation of Spacecraft Fuel Slosh Model

Science.gov (United States)

Gangadharan, Sathya; Sudermann, James; Marlowe, Andrea; Njengam Charles

2004-01-01

Fuel slosh in the upper stages of a spinning spacecraft during launch has been a long standing concern for the success of a space mission. Energy loss through the movement of the liquid fuel in the fuel tank affects the gyroscopic stability of the spacecraft and leads to nutation (wobble) which can cause devastating control issues. The rate at which nutation develops (defined by Nutation Time Constant (NTC can be tedious to calculate and largely inaccurate if done during the early stages of spacecraft design. Pure analytical means of predicting the influence of onboard liquids have generally failed. A strong need exists to identify and model the conditions of resonance between nutation motion and liquid modes and to understand the general characteristics of the liquid motion that causes the problem in spinning spacecraft. A 3-D computerized model of the fuel slosh that accounts for any resonant modes found in the experimental testing will allow for increased accuracy in the overall modeling process. Development of a more accurate model of the fuel slosh currently lies in a more generalized 3-D computerized model incorporating masses, springs and dampers. Parameters describing the model include the inertia tensor of the fuel, spring constants, and damper coefficients. Refinement and understanding the effects of these parameters allow for a more accurate simulation of fuel slosh. The current research will focus on developing models of different complexity and estimating the model parameters that will ultimately provide a more realistic prediction of Nutation Time Constant obtained through simulation.

Large angle tracking and high discriminating tracking in nuclear emulsion

International Nuclear Information System (INIS)

Matsuo, Tomokazu; Shibuya, Hiroshi; Ogawa, Satoru; Fukuda, Tsutomu; Mikado, Shoji

2015-01-01

Nuclear emulsion is a high resolution and re-analyzable detector. Conventional “Track Selector” which have angle acceptance |tan θ|<0.6 are widely used to find tracks in emulsion. We made a new track selector “Fine Track Selector” (FTS) which has large angle acceptance and high discriminating ability. The FTS reduces fake tracks using new algorithms, navigation etc. FTS also keeps finding efficiency of tracks around 90% in an angle range of |tan θ| < 3.5. FTS was applied to the τ candidate in OPERA and no additional tracks found. FTS will be useful to our new J-PARC emulsion experiment.

Relativity time-delay experiments utilizing 'Mariner' spacecraft

Science.gov (United States)

Esposito, P. B.; Anderson, J. D.

1974-01-01

Relativity predicts that the transit time of a signal propagated from the earth to a spacecraft and retransmitted back to earth ought to exhibit an additional, variable time delay. The present work describes some of the analytical techniques employed in experiments using Mariner spacecraft designed to test the accuracy of this prediction. Two types of data are analyzed in these relativity experiments; these include phase-coherent, two-way Doppler shift and round-trip, transit-time measurements. Results of Mariner 6 and 7 relativistic time-delay experiments are in agreement with Einstein's theory of general relativity with an uncertainty of 3%.

Testing programs for the Multimission Modular Spacecraft

Science.gov (United States)

Greenwell, T. J.

1978-01-01

The Multimission Modular Spacecraft (MMS) provides a standard spacecraft bus to a user for a variety of space missions ranging from near-earth to synchronous orbits. The present paper describes the philosophy behind the MMS module test program and discusses the implementation of the test program. It is concluded that the MMS module test program provides an effective and comprehensive customer buy-off at the subsystem contractor's plant, is an optimum approach for checkout of the subsystems prior to use for on-orbit servicing in the Shuttle Cargo Bay, and is a cost-effective technique for environmental testing.

Guidance and Control of Position and Attitude for Rendezvous and Dock/Berthing with a Noncooperative/Target Spacecraft

Directory of Open Access Journals (Sweden)

Gilberto Arantes

2014-01-01

Full Text Available Noncooperative target spacecrafts are those assets in orbit that cannot convey any information about their states (position, attitude, and velocities or facilitate rendezvous and docking/berthing (RVD/B process. Designing a guidance, navigation, and control (GNC module for the chaser in a RVD/B mission with noncooperative target should be inevitably solved for on-orbit servicing technologies. The proximity operations and the guidance for achieving rendezvous problems are addressed in this paper. The out-of-plane maneuvers of proximity operations are explored with distinct subphases, including a chaser far approach in the target’s orbit to the first hold point and a closer approach to the final berthing location. Accordingly, guidance solutions are chosen for each subphase from the standard Hill based Closhessy-Willtshire (CW solution, elliptical fly-around, and Glideslope algorithms. The control is based on a linear quadratic regulator approach (LQR. At the final berthing location, attitude tracker based on a proportional derivative (PD form is tested to synchronize the chaser and target attitudes. The paper analyzes the performance of both controllers in terms of the tracking ability and the robustness. Finally, it prescribes any restrictions that may be imposed on the guidance during any subphase which can help to improve the controllers tracking ability.

SHARP: A multi-mission AI system for spacecraft telemetry monitoring and diagnosis

Science.gov (United States)

Lawson, Denise L.; James, Mark L.

1989-01-01

The Spacecraft Health Automated Reasoning Prototype (SHARP) is a system designed to demonstrate automated health and status analysis for multi-mission spacecraft and ground data systems operations. Telecommunications link analysis of the Voyager II spacecraft is the initial focus for the SHARP system demonstration which will occur during Voyager's encounter with the planet Neptune in August, 1989, in parallel with real-time Voyager operations. The SHARP system combines conventional computer science methodologies with artificial intelligence techniques to produce an effective method for detecting and analyzing potential spacecraft and ground systems problems. The system performs real-time analysis of spacecraft and other related telemetry, and is also capable of examining data in historical context. A brief introduction is given to the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory. The current method of operation for monitoring the Voyager Telecommunications subsystem is described, and the difficulties associated with the existing technology are highlighted. The approach taken in the SHARP system to overcome the current limitations is also described, as well as both the conventional and artificial intelligence solutions developed in SHARP.

Influence of tracks densities in solid state nuclear track detectors

International Nuclear Information System (INIS)

Guedes O, S.; Hadler N.; Lunes, P.; Saenz T, C.

1996-01-01

When Solid State Nuclear Track Detectors (SSNTD) is employed to measure nuclear tracks produced mainly by fission fragments and alpha particles, it is considered that the tracks observation work is performed under an efficiency, ε 0 , which is independent of the track density (number of tracks/area unit). There are not published results or experimental data supporting such an assumption. In this work the dependence of ε 0 with track density is studied basing on experimental data. To perform this, pieces of CR-39 cut from a sole 'mother sheet' were coupled to thin uranium films for different exposition times and the resulting ratios between track density and exposition time were compared. Our results indicate that ε 0 is constant for track densities between 10 3 and 10 5 cm -2 . At our etching conditions track overlapping makes impossible the counting for densities around 1.7 x 10 5 cm -2 . For track densities less than 10 3 cm -2 , ε 0 , was not observed to be constant. (authors). 4 refs., 2 figs

Protecting Spacecraft Fragments from Exposure to Small Debris

OpenAIRE

V. V. Zelentsov

2015-01-01

Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable ...

Short rendezvous missions for advanced Russian human spacecraft

Science.gov (United States)

Murtazin, Rafail F.; Budylov, Sergey G.

2010-10-01

The two-day stay of crew in a limited inhabited volume of the Soyuz-TMA spacecraft till docking to ISS is one of the most stressful parts of space flight. In this paper a number of possible ways to reduce the duration of the free flight phase are considered. The duration is defined by phasing strategy that is necessary for reduction of the phase angle between the chaser and target spacecraft. Some short phasing strategies could be developed. The use of such strategies creates more comfortable flight conditions for crew thanks to short duration and additionally it allows saving spacecraft's life support resources. The transition from the methods of direct spacecraft rendezvous using one orbit phasing (first flights of " Vostok" and " Soyuz" vehicles) to the currently used methods of two-day rendezvous mission can be observed in the history of Soviet manned space program. For an advanced Russian human rated spacecraft the short phasing strategy is recommended, which can be considered as a combination between the direct and two-day rendezvous missions. The following state of the art technologies are assumed available: onboard accurate navigation; onboard computations of phasing maneuvers; launch vehicle with high accuracy injection orbit, etc. Some operational requirements and constraints for the strategies are briefly discussed. In order to provide acceptable phase angles for possible launch dates the experience of the ISS altitude profile control can be used. As examples of the short phasing strategies, the following rendezvous missions are considered: direct ascent, short mission with the phasing during 3-7 orbits depending on the launch date (nominal or backup). For each option statistical modeling of the rendezvous mission is fulfilled, as well as an admissible phase angle range, accuracy of target state vector and addition fuel consumption coming out of emergency is defined. In this paper an estimation of pros and cons of all options is conducted.

Computational Model for Spacecraft/Habitat Volume

Data.gov (United States)

National Aeronautics and Space Administration — Please note that funding to Dr. Simon Hsiang, a critical co-investigator for the development of the Spacecraft Optimization Layout and Volume (SOLV) model, was...

Spacecraft Cabin Particulate Monitor, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to design, build and test an optical extinction monitor for the detection of spacecraft cabin particulates. This monitor will be sensitive to particle...

The relationship between fission track length and track density in apatite

International Nuclear Information System (INIS)

Laslett, G.M.; Gleadow, A.J.W.; Duddy, I.R.

1984-01-01

Fission track dating is based upon an age equation derived from a random line segment model for fission tracks. This equation contains the implicit assumption of a proportional relationship between the true mean length of fission tracks and their track density in an isotropic medium. Previous experimental investigation of this relationship for both spontaneous and induced tracks in apatite during progressive annealment model in an obvious fashion. Corrected equations relating track length and density for apatite, an anisotropic mineral, show that the proportionality in this case is between track density and a length factor which is a generalization of the mean track length combining the actual length and crystallographic orientation of the track. This relationship has been experimentally confirmed for induced tracks in Durango apatite, taking into account bias in sampling of the track lengths, and the effect of the bulk etching velocity. (author)

Thermal elastic shock and its effect on TOPEX spacecraft attitude control

Science.gov (United States)

Zimbelman, Darrell F.

1991-01-01

Thermal elastic shock (TES) is a twice per orbit impulsive disturbance torque experienced by low-Earth orbiting spacecraft. The fundamental equations used to model the TES disturbance torque for typical spacecraft appendages (e.g., solar arrays and antenna booms) are derived in detail. In particular, the attitude-pointing performance of the TOPEX spacecraft, when subjected to the TES disturbance, is analyzed using a three-axis nonlinear time-domain simulation. Results indicate that the TOPEX spacecraft could exceed its roll-axis attitude-control requirement during penumbral transitions, and remain in violation for approximately 150 sec each orbit until the umbra collapses. A localized active-control system is proposed as a solution to minimize and/or eliminate the degrading effects of the TES disturbance.

Symplectic Tracking of Multi-Isotopic Heavy-Ion Beams in SixTrack

CERN Document Server

Hermes, Pascal; De Maria, Riccardo

2016-01-01

The software SixTrack provides symplectic proton tracking over a large number of turns. The code is used for the tracking of beam halo particles and the simulation of their interaction with the collimators to study the efficiency of the LHC collimation system. Tracking simulations for heavy-ion beams require taking into account the mass to charge ratio of each particle because heavy ions can be subject to fragmentation at their passage through the collimators. In this paper we present the derivation of a Hamiltonian for multi-isotopic heavy-ion beams and symplectic tracking maps derived from it. The resulting tracking maps were implemented in the tracking software SixTrack. With this modification, SixTrack can be used to natively track heavy-ion beams of multiple isotopes through a magnetic accelerator lattice.

Spacecraft Cabin Particulate Monitor, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — We have built and tested an optical extinction monitor for the detection of spacecraft cabin particulates. This sensor sensitive to particle sizes ranging from a few...

Experimental Validation of Pulse Phase Tracking for X-Ray Pulsar Based

Science.gov (United States)

Anderson, Kevin

2012-01-01

Pulsars are a form of variable celestial source that have shown to be usable as aids for autonomous, deep space navigation. Particularly those sources emitting in the X-ray band are ideal for navigation due to smaller detector sizes. In this paper X-ray photons arriving from a pulsar are modeled as a non-homogeneous Poisson process. The method of pulse phase tracking is then investigated as a technique to measure the radial distance traveled by a spacecraft over an observation interval. A maximum-likelihood phase estimator (MLE) is used for the case where the observed frequency signal is constant. For the varying signal frequency case, an algorithm is used in which the observation window is broken up into smaller blocks over which an MLE is used. The outputs of this phase estimation process were then looped through a digital phase-locked loop (DPLL) in order to reduce the errors and produce estimates of the doppler frequency. These phase tracking algorithms were tested both in a computer simulation environment and using the NASA Goddard Space flight Center X-ray Navigation Laboratory Testbed (GXLT). This provided an experimental validation with photons being emitted by a modulated X-ray source and detected by a silicon-drift detector. Models of the Crab pulsar and the pulsar B1821-24 were used in order to generate test scenarios. Three different simulated detector trajectories were used to be tracked by the phase tracking algorithm: a stationary case, one with constant velocity, and one with constant acceleration. All three were performed in one-dimension along the line of sight to the pulsar. The first two had a constant signal frequency and the third had a time varying frequency. All of the constant frequency cases were processed using the MLE, and it was shown that they tracked the initial phase within 0.15% for the simulations and 2.5% in the experiments, based on an average of ten runs. The MLE-DPLL cascade version of the phase tracking algorithm was used in

PolarTrack: Optical Outside-In Device Tracking that Exploits Display Polarization

DEFF Research Database (Denmark)

Rädle, Roman; Jetter, Hans-Christian; Fischer, Jonathan

2018-01-01

PolarTrack is a novel camera-based approach to detecting and tracking mobile devices inside the capture volume. In PolarTrack, a polarization filter continuously rotates in front of an off-the-shelf color camera, which causes the displays of observed devices to periodically blink in the camera feed....... The periodic blinking results from the physical characteristics of current displays, which shine polarized light either through an LC overlay to produce images or through a polarizer to reduce light reflections on OLED displays. PolarTrack runs a simple detection algorithm on the camera feed to segment...... displays and track their locations and orientations, which makes PolarTrack particularly suitable as a tracking system for cross-device interaction with mobile devices. Our evaluation of PolarTrack's tracking quality and comparison with state-of-the-art camera-based multi-device tracking showed a better...

High Accuracy Tracking of Space-Borne Non-Cooperative Targets

DEFF Research Database (Denmark)

Pedersen, David Arge Klevang

for the spacecraft to navigate safely and autonomously towards the target. These methods are applied on three distinct study cases, which are based on the platform of the microASC instrument. In relation to the Mars2020 rover, a structured light system is used to navigate the PIXL instrument towards the Martian...... surface, whose objective is to seek evidence of ancient life in the form of chemical biosignatures. The structured light is a subsystem of the PIXL instrument consisting of two active lasers and an imager. The structured light makes use of active triangulation to support a safe approach towards...... team and processing of the captured data was recognized with two Group Achievement Awards from the National Aeronautics and Space Administration. With today's advancement in autonomy, the focus is set on in-flight tracking of a non-cooperative artificial satellite with the end goal of capturing...

On increasing the spectral efficiency and transmissivity in the data transmission channel on the spacecraft-ground tracking station line

Science.gov (United States)

Andrianov, M. N.; Kostenko, V. I.; Likhachev, S. F.

2018-01-01

The algorithms for achieving a practical increase in the rate of data transmission on the space-craft-ground tracking station line has been considered. This increase is achieved by applying spectral-effective modulation techniques, the technology of orthogonal frequency compression of signals using millimeterrange radio waves. The advantages and disadvantages of each of three algorithms have been revealed. A significant advantage of data transmission in the millimeter range has been indicated.

Laboratory investigation of antenna signals from dust impacts on spacecraft

Science.gov (United States)

Sternovsky, Zoltan; Collette, Andrew; Malaspina, David M.; Thayer, Frederick

2016-04-01

Electric field and plasma wave instruments act as dust detectors picking up voltage pulses induced by impacts of particulates on the spacecraft body. These signals enable the characterization of cosmic dust environments even with missions without dedicated dust instruments. For example, the Voyager 1 and 2 spacecraft performed the first detection of dust particles near Uranus, Neptune, and in the outer solar system [Gurnett et al., 1987, 1991, 1997]. The two STEREO spacecraft observed distinct signals at high rate that were interpreted as nano-sized particles originating from near the Sun and accelerated to high velocities by the solar wind [MeyerVernet et al, 2009a, Zaslavsky et al., 2012]. The MAVEN spacecraft is using the antennas onboard to characterize the dust environment of Mars [Andersson et al., 2014] and Solar Probe Plus will do the same in the inner heliosphere. The challenge, however, is the correct interpretation of the impact signals and calculating the mass of the dust particles. The uncertainties result from the incomplete understanding of the signal pickup mechanisms, and the variation of the signal amplitude with impact location, the ambient plasma environment, and impact speed. A comprehensive laboratory study of impact generated antenna signals has been performed recently using the IMPACT dust accelerator facility operated at the University of Colorado. Dust particles of micron and submicron sizes with velocities of tens of km/s are generated using a 3 MV electrostatic analyzer. A scaled down model spacecraft is exposed to the dust impacts and one or more antennas, connected to sensitive electronics, are used to detect the impact signals. The measurements showed that there are three clearly distinct signal pickup mechanisms due to spacecraft charging, antenna charging and antenna pickup sensing space charge from the expanding plasma cloud. All mechanisms vary with the spacecraft and antenna bias voltages and, furthermore, the latter two

Fan tomography of the tropospheric water vapor for the calibration of the Ka band tracking of the Bepi-Colombo spacecraft (MORE experiment).

Science.gov (United States)

Barriot, Jean-Pierre; Serafini, Jonathan; Sichoix, Lydie

2012-07-01

The radiosciences Bepi-Colombo MORE experiment will use X/X, X/Ka and Ka/Ka band radio links to make accurate measurements of the spacecraft range and range rate. Tropospheric zenith wet delays range from 1.5 cm to 10 cm, with high variability (less than 1000 s) and will impair these accurate measurements. Conditions vary from summer (worse) to winter (better), from day (worse) to night (better). These wet delays cannot be estimated from ground weather measurements and alternative calibration methods should be used in order to cope with the MORE requirements (no more than 3 mm at 1000 s). Due to the Mercury orbit, MORE measurements will be performed by daylight and more frequently in summer than in winter (from Northern hemisphere). Two systems have been considered to calibrate this wet delay: Water Vapour Radiometers (WVRs) and GPS receivers. The Jet Propulsion Laboratory has developed a new class of WVRs reaching a 5 percent accuracy for the wet delay calibration (0.75 mm to 5 mm), but these WVRs are expensive to build and operate. GPS receivers are also routinely used for the calibration of data from NASA Deep Space probes, but several studies have shown that GPS receivers can give good calibration (through wet delay mapping functions) for long time variations, but are not accurate enough for short time variations (100 to 1000 s), and that WVRs must be used to efficiently calibrate the wet troposphere delays over such time spans. We think that such a calibration could be done by assimilating data from all the GNSS constellations (GPS, GLONASS, Galileo, Beidou and IRNSS) that will be available at the time of the Bepi-Colombo arrival at Mercury (2021), provided that the underlying physics of the turbulent atmosphere and evapotranspiration processes are properly taken into account at such time scales. This implies to do a tomographic image of the troposphere overlying each Deep Space tracking station at time scales of less than 1000 s. For this purpose, we have

On TTEthernet for Integrated Fault-Tolerant Spacecraft Networks

Science.gov (United States)

Loveless, Andrew

2015-01-01

There has recently been a push for adopting integrated modular avionics (IMA) principles in designing spacecraft architectures. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and de- sign complexity. Ethernet technology is attractive for inclusion in more integrated avionic systems due to its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components. Furthermore, Ethernet can be augmented with a variety of quality of service (QoS) enhancements that enable its use for transmitting critical data. TTEthernet introduces a decentralized clock synchronization paradigm enabling the use of time-triggered Ethernet messaging appropriate for hard real-time applications. TTEthernet can also provide two forms of event-driven communication, therefore accommodating the full spectrum of traffic criticality levels required in IMA architectures. This paper explores the application of TTEthernet technology to future IMA spacecraft architectures as part of the Avionics and Software (A&S) project chartered by NASA's Advanced Exploration Systems (AES) program.

SSTI- Lewis Spacecraft Nickel-Hydrogen Battery

Science.gov (United States)

Tobias, R. F.

1997-01-01

Topics considered include: NASA-Small Spacecraft Technology Initiative (SSTI) objectives, SSTI-Lewis overview, battery requirement, two cells Common Pressure Vessel (CPV) design summary, CPV electric performance, battery design summary, battery functional description, battery performance.

Evolution of NASA's Near-Earth Tracking and Data Relay Satellite System (TDRSS)

Science.gov (United States)

Flaherty, Roger; Stocklin, Frank; Weinberg, Aaron

2006-01-01

NASA's Tracking and Data Relay Satellite System (TDRSS) is now in its 23rd year of operations and its spacecraft fleet includes three second-generation spacecraft launched since the year 2000; a figure illustrates the first generation TDRSS spacecraft. During this time frame the TDRSS has provided communications relay support to a broad range of missions, with emphasis on low-earth-orbiting (LEO) spacecraft that include unmanned science spacecraft (e.g., Hubble Space Telescope), and human spaceflight (Space Shuttle and Space Station). Furthermore, the TDRSS has consistently demonstrated its uniqueness and adaptability in several ways. First, its S- and K-band services, combined with its multi-band/steerable single-access (SA) antennas and ground-based configuration flexibility, have permitted the mission set to expand to unique users such as scientific balloons and launch vehicles. Second, the bent-pipe nature of the system has enabled the introduction of new/improved services via technology insertion and upgrades at each of the ground terminals; a specific example here is the Demand Access Service (DAS), which, for example, is currently providing science-alert support to NASA science missions Third, the bent-pipe nature of the system, combined with the flexible ground-terminal signal processing architecture has permitted the demonstration/vaIidation of new techniques/services/technologies via a real satellite channel; over the past 10+ years these have, for example, included demonstrations/evaluations of emerging modulation/coding techniques. Given NASA's emerging Exploration plans, with missions beginning later this decade and expanding for decades to come, NASA is currently planning the development of a seamless, NASA-wide architecture that must accommodate missions from near-earth to deep space. Near-earth elements include Ground-Network (GN) and Near-Earth Relay (NER) components and both must efficiently and seamlessly support missions that encompass: earth

Particle-in-Cell Simulation Study on the Floating Potential of Spacecraft in the Low Earth Orbit

International Nuclear Information System (INIS)

Tang Daotan; Yang Shengsheng; Zheng Kuohai; Qin Xiaogang; Li Detian; Liu Qing; Zhao Chengxuan; Du Shanshan

2015-01-01

In order to further understand the characteristics of the floating potential of low earth orbit spacecraft, the effects of the electron current collection area, background electron temperature, photocurrent emission, spacecraft wake, and the shape of spacecraft on spacecraft floating potential were studied here by particle-in-cell simulation in the low earth orbit. The simulation results show that the electron current collection area and background electron temperature impact on the floating potential by changing the electron current collection of spacecraft. By increasing the electron current collection area or background electron temperature, the spacecraft will float at a lower electric potential with respect to the surrounding plasma. However, the spacecraft wake affects the floating potential by increasing the ion current collected by spacecraft. The emission of the photocurrent from the spacecraft surface, which compensates for the electrons collected from background plasma, causes the floating potential to increase. The shape of the spacecraft is also an important factor influencing the floating potential. (paper)

Assessment of the Use of Nanofluids in Spacecraft Active Thermal Control Systems

Science.gov (United States)

Ungar, Eugene K.; Erickson, Lisa R.

2011-01-01

The addition of metallic nanoparticles to a base heat transfer fluid can dramatically increase its thermal conductivity. These nanofluids have been shown to have advantages in some heat transport systems. Their enhanced properties can allow lower system volumetric flow rates and can reduce the required pumping power. Nanofluids have been suggested for use as working fluids for spacecraft Active Thermal Control Systems (ATCSs). However, there are no studies showing the end-to-end effect of nanofluids on the design and performance of spacecraft ATCSs. In the present work, a parametric study is performed to assess the use of nanofluids in a spacecraft ATCSs. The design parameters of the current Orion capsule and the tabulated thermophysical properties of nanofluids are used to assess the possible benefits of nanofluids and how their incorporation affects the overall design of a spacecraft ATCS. The study shows that the unique system and component-level design parameters of spacecraft ATCSs render them best suited for pure working fluids. The addition of nanoparticles to typical spacecraft thermal control working fluids actually results in an increase in the system mass and required pumping power.

Spacecraft Fire Safety Research at NASA Glenn Research Center

Science.gov (United States)

Meyer, Marit

2016-01-01

Appropriate design of fire detection systems requires knowledge of both the expected fire signature and the background aerosol levels. Terrestrial fire detection systems have been developed based on extensive study of terrestrial fires. Unfortunately there is no corresponding data set for spacecraft fires and consequently the fire detectors in current spacecraft were developed based upon terrestrial designs. In low gravity, buoyant flow is negligible which causes particles to concentrate at the smoke source, increasing their residence time, and increasing the transport time to smoke detectors. Microgravity fires have significantly different structure than those in 1-g which can change the formation history of the smoke particles. Finally the materials used in spacecraft are different from typical terrestrial environments where smoke properties have been evaluated. It is critically important to detect a fire in its early phase before a flame is established, given the fixed volume of air on any spacecraft. Consequently, the primary target for spacecraft fire detection is pyrolysis products rather than soot. Experimental investigations have been performed at three different NASA facilities which characterize smoke aerosols from overheating common spacecraft materials. The earliest effort consists of aerosol measurements in low gravity, called the Smoke Aerosol Measurement Experiment (SAME), and subsequent ground-based testing of SAME smoke in 55-gallon drums with an aerosol reference instrument. Another set of experiments were performed at NASAs Johnson Space Center White Sands Test Facility (WSTF), with additional fuels and an alternate smoke production method. Measurements of these smoke products include mass and number concentration, and a thermal precipitator was designed for this investigation to capture particles for microscopic analysis. The final experiments presented are from NASAs Gases and Aerosols from Smoldering Polymers (GASP) Laboratory, with selected

Small Spacecraft Constellation Concept for Mars Atmospheric Radio Occultations

Science.gov (United States)

Asmar, S. W.; Mannucci, A. J.; Ao, C. O.; Kobayashi, M. M.; Lazio, J.; Marinan, A.; Massone, G.; McCandless, S. E.; Preston, R. A.; Seubert, J.; Williamson, W.

2017-12-01

First demonstrated in 1965 when Mariner IV flew by Mars and determined the salient features of its atmosphere, radio occultation experiments have been carried out on numerous planetary missions with great discoveries. These experiments utilize the now classic configuration of a signal from a single planetary spacecraft to Earth receiving stations, where the science data are acquired. The Earth science community advanced the technique to utilizing a constellation of spacecraft with the radio occultation links between the spacecraft, enabled by the infrastructure of the Global Positioning System. With the advent of small and less costly spacecraft, such as planetary CubeSats and other variations, such as the anticipated innovative Mars Cube One mission, crosslinks among small spacecraft can be used to study other planets in the near future. Advantages of this type of experiment include significantly greater geographical coverage, which could reach global coverage over a few weeks with a small number of spacecraft. Repeatability of the global coverage can lead to examining temperature-pressure profiles and ionospheric electron density profiles, on daily, seasonal, annual, or other time scales of interest. The higher signal-to-noise ratio for inter-satellite links, compared to a link to Earth, decreases the design demands on the instrumentation (smaller antennas and transmitters, etc.). After an actual Mars crosslink demonstration, this concept has been in development using Mars as a possible target. Scientific objectives, delivery methods, operational scenarios and end-to-end configuration have been documented. Science objectives include determining the state and variability of the lower Martian atmosphere, which has been an identified as a high priority objective by the Mars Exploration Program Analysis Group, particularly as it relates to entry, descent, and landing and ascent for future crewed and robotic missions. This paper will present the latest research on the

Space environment studies for the SZ-4 spacecraft

International Nuclear Information System (INIS)

Ye Zonghai

2004-01-01

The space environment, especially the solar-terrestrial space environment, has close bearings on mankind's astronautical activities. An overview is presented of the space environment and safeguard services on the 'SZ' series of spacecraft, with special reference to the SZ-4 spacecraft. These include monitoring of the space environment on SZ-4, studies on its distribution, variation and effects on astronautical performance, as well as space environment forecasts for safe launching, normal operation and safe return of SZ-4. Current progress both in China and overseas is covered

A Comparison of Learning Technologies for Teaching Spacecraft Software Development

Science.gov (United States)

Straub, Jeremy

2014-01-01

The development of software for spacecraft represents a particular challenge and is, in many ways, a worst case scenario from a design perspective. Spacecraft software must be "bulletproof" and operate for extended periods of time without user intervention. If the software fails, it cannot be manually serviced. Software failure may…

Apollo Spacecraft 012 Command/Service Module being moved to Operations bldg

Science.gov (United States)

1967-01-01

Transfer of Apollo Spacecraft 012 Command/Service Module for mating to the Saturn Lunar Module Adapter No. 05 in the Manned Spacecraft Operations bldg. S/C 012 will be flown on the Apollo/Saturn 204 mission.

Proposed gravity-gradient dynamics experiments in lunar orbit using the RAE-B spacecraft

Science.gov (United States)

Blanchard, D. L.; Walden, H.

1973-01-01

A series of seven gravity-gradient dynamics experiments is proposed utilizing the Radio Astronomy Explorer (RAE-B) spacecraft in lunar orbit. It is believed that none of the experiments will impair the spacecraft structure or adversely affect the continuation of the scientific mission of the satellite. The first experiment is designed to investigate the spacecraft dynamical behavior in the absence of libration damper action and inertia. It requires stable gravity-gradient capture of the spacecraft in lunar orbit with small amplitude attitude librations as a prerequisite. Four subsequent experiments involve partial retraction, ultimately followed by full redeployment, of one or two of the 230-meter booms forming the lunar-directed Vee-antenna. These boom length change operations will induce moderate amplitude angular librations of the spacecraft.

Track reconstruction at the ILC: the ILD tracking software

International Nuclear Information System (INIS)

Gaede, Frank; Aplin, Steven; Rosemann, Christoph; Voutsinas, Georgios; Glattauer, Robin

2014-01-01

One of the key requirements for Higgs physics at the International Linear Collider ILC is excellent track reconstruction with very good momentum and impact parameter resolution. ILD is one of the two detector concepts at the ILC. Its central tracking system comprises of an outer Si-tracker, a highly granular TPC, an intermediate silicon tracker and a pixel vertex detector, and it is complemented by silicon tracking disks in the forward direction. Large hit densities from beam induced coherent electron-positron pairs at the ILC pose an additional challenge to the pattern recognition algorithms. We present the recently developed new ILD tracking software, the pattern recognition algorithms that are using clustering techniques, Cellular Automatons and Kalman filter based track extrapolation. The performance of the ILD tracking system is evaluated using a detailed simulation including dead material, gaps and imperfections.

Darwinian Spacecraft: Soft Computing Strategies Breeding Better, Faster Cheaper

Science.gov (United States)

Noever, David A.; Baskaran, Subbiah

1999-01-01

Computers can create infinite lists of combinations to try to solve a particular problem, a process called "soft-computing." This process uses statistical comparables, neural networks, genetic algorithms, fuzzy variables in uncertain environments, and flexible machine learning to create a system which will allow spacecraft to increase robustness, and metric evaluation. These concepts will allow for the development of a spacecraft which will allow missions to be performed at lower costs.

Triple-root jump in spacecraft potential due to electron beam emission or impact

International Nuclear Information System (INIS)

Lai, S.T.

1992-01-01

Triple-root jump in spacecraft potential is well understood in the double Maxwellian model of the natural space environment. In this paper, however, the author points out that triple-root jumps in spacecraft potential may also occur during photoemission or electron beam emission from a spacecraft. Impact of an incoming electron beam on a spacecraft may also cause triple-root jumps provided that the beam, ambient plasma, and surface parameters satisfy certain inequality conditions. The parametric conditions under which such beam induced triple-root jumps may occur are presented

Astronaut L. Gordon Cooper is assisted into his spacecraft for tests

Science.gov (United States)

1963-01-01

NASA and McDonnell Aircraft Corp. spacecraft technicians assist Astronaut L. Gordon Cooper into his spacecraft prior to undergoing tests in the altitude chamber. These tests are used to determine the operating characteristcs of the overall environmental control system.

Ascent performance feasibility for next-generation spacecraft

Science.gov (United States)

Mancuso, Salvatore Massimo

This thesis deals with the optimization of the ascent trajectories for single-stage suborbital (SSSO), single-stage-to-orbit (SSTO), and two-stage-to-orbit (TSTO) rocket-powered spacecraft. The maximum payload weight problem has been solved using the sequential gradient-restoration algorithm. For the TSTO case, some modifications to the original version of the algorithm have been necessary in order to deal with discontinuities due to staging and the fact that the functional being minimized depends on interface conditions. The optimization problem is studied for different values of the initial thrust-to-weight ratio in the range 1.3 to 1.6, engine specific impulse in the range 400 to 500 sec, and spacecraft structural factor in the range 0.08 to 0.12. For the TSTO configuration, two subproblems are studied: uniform structural factor between stages and nonuniform structural factor between stages. Due to the regular behavior of the results obtained, engineering approximations have been developed which connect the maximum payload weight to the engine specific impulse and spacecraft structural factor; in turn, this leads to useful design considerations. Also, performance sensitivity to the scale of the aerodynamic drag is studied, and it is shown that its effect on payload weight is relatively small, even for drag changes approaching ± 50%. The main conclusions are that: the design of a SSSO configuration appears to be feasible; the design of a SSTO configuration might be comfortably feasible, marginally feasible, or unfeasible, depending on the parameter values assumed; the design of a TSTO configuration is not only feasible, but its payload appears to be considerably larger than that of a SSTO configuration. Improvements in engine specific impulse and spacecraft structural factor are desirable and crucial for SSTO feasibility; indeed, it appears that aerodynamic improvements do not yield significant improvements in payload weight.

Spacecraft control center automation using the generic inferential executor (GENIE)

Science.gov (United States)

Hartley, Jonathan; Luczak, Ed; Stump, Doug

1996-01-01

The increasing requirement to dramatically reduce the cost of mission operations led to increased emphasis on automation technology. The expert system technology used at the Goddard Space Flight Center (MD) is currently being applied to the automation of spacecraft control center activities. The generic inferential executor (GENIE) is a tool which allows pass automation applications to be constructed. The pass script templates constructed encode the tasks necessary to mimic flight operations team interactions with the spacecraft during a pass. These templates can be configured with data specific to a particular pass. Animated graphical displays illustrate the progress during the pass. The first GENIE application automates passes of the solar, anomalous and magnetospheric particle explorer (SAMPEX) spacecraft.

SHARP: A multi-mission artificial intelligence system for spacecraft telemetry monitoring and diagnosis

Science.gov (United States)

Lawson, Denise L.; James, Mark L.

1989-01-01

The Spacecraft Health Automated Reasoning Prototype (SHARP) is a system designed to demonstrate automated health and status analysis for multi-mission spacecraft and ground data systems operations. Telecommunications link analysis of the Voyager 2 spacecraft is the initial focus for the SHARP system demonstration which will occur during Voyager's encounter with the planet Neptune in August, 1989, in parallel with real time Voyager operations. The SHARP system combines conventional computer science methodologies with artificial intelligence techniques to produce an effective method for detecting and analyzing potential spacecraft and ground systems problems. The system performs real time analysis of spacecraft and other related telemetry, and is also capable of examining data in historical context. A brief introduction is given to the spacecraft and ground systems monitoring process at the Jet Propulsion Laboratory. The current method of operation for monitoring the Voyager Telecommunications subsystem is described, and the difficulties associated with the existing technology are highlighted. The approach taken in the SHARP system to overcome the current limitations is also described, as well as both the conventional and artificial intelligence solutions developed in SHARP.

Data combinations accounting for LISA spacecraft motion

International Nuclear Information System (INIS)

Shaddock, Daniel A.; Tinto, Massimo; Estabrook, Frank B.; Armstrong, J.W.

2003-01-01

The laser interferometer space antenna is an array of three spacecraft in an approximately equilateral triangle configuration which will be used as a low-frequency gravitational wave detector. We present here new generalizations of the Michelson- and Sagnac-type time-delay interferometry data combinations. These combinations cancel laser phase noise in the presence of different up and down propagation delays in each arm of the array, and slowly varying systematic motion of the spacecraft. The gravitational wave sensitivities of these generalized combinations are the same as previously computed for the stationary cases, although the combinations are now more complicated. We introduce a diagrammatic representation to illustrate that these combinations are actually synthesized equal-arm interferometers

Study of the Spacecraft Potential Under Active Control and Plasma Density Estimates During the MMS Commissioning Phase

Science.gov (United States)

Andriopoulou, M.; Nakamura, R.; Torkar, K.; Baumjohann, W.; Torbert, R. B.; Lindqvist, P.-A.; Khotyaintsev, Y. V.; Dorelli, John Charles; Burch, J. L.; Russell, C. T.

2016-01-01

Each spacecraft of the recently launched magnetospheric multiscale MMS mission is equipped with Active Spacecraft Potential Control (ASPOC) Instruments, which control the spacecraft potential in order to reduce spacecraft charging effects. ASPOC typically reduces the spacecraft potential to a few volts. On several occasions during the commissioning phase of the mission, the ASPOC instruments were operating only on one spacecraft at a time. Taking advantage of such intervals, we derive photoelectron curves and also perform reconstructions of the uncontrolled spacecraft potential for the spacecraft with active control and estimate the electron plasma density during those periods. We also establish the criteria under which our methods can be applied.

Global Precipitation Measurement (GPM) Spacecraft Lithium Ion Battery Micro-Cycling Investigation

Science.gov (United States)

Dakermanji, George; Lee, Leonine; Spitzer, Thomas

2016-01-01

The Global Precipitation Measurement (GPM) spacecraft was jointly developed by NASA and JAXA. It is a Low Earth Orbit (LEO) spacecraft launched on February 27, 2014. The power system is a Direct Energy Transfer (DET) system designed to support 1950 watts orbit average power. The batteries use SONY 18650HC cells and consist of three 8s by 84p batteries operated in parallel as a single battery. During instrument integration with the spacecraft, large current transients were observed in the battery. Investigation into the matter traced the cause to the Dual-Frequency Precipitation Radar (DPR) phased array radar which generates cyclical high rate current transients on the spacecraft power bus. The power system electronics interaction with these transients resulted in the current transients in the battery. An accelerated test program was developed to bound the effect, and to assess the impact to the mission.

Toward autonomous spacecraft

Science.gov (United States)

Fogel, L. J.; Calabrese, P. G.; Walsh, M. J.; Owens, A. J.

1982-01-01

Ways in which autonomous behavior of spacecraft can be extended to treat situations wherein a closed loop control by a human may not be appropriate or even possible are explored. Predictive models that minimize mean least squared error and arbitrary cost functions are discussed. A methodology for extracting cyclic components for an arbitrary environment with respect to usual and arbitrary criteria is developed. An approach to prediction and control based on evolutionary programming is outlined. A computer program capable of predicting time series is presented. A design of a control system for a robotic dense with partially unknown physical properties is presented.

Results of Large-Scale Spacecraft Flammability Tests

Science.gov (United States)

Ferkul, Paul; Olson, Sandra; Urban, David L.; Ruff, Gary A.; Easton, John; T'ien, James S.; Liao, Ta-Ting T.; Fernandez-Pello, A. Carlos; Torero, Jose L.; Eigenbrand, Christian;

Optimal Weighting of Multi-Spacecraft Data to Estimate Gradients of Physical Fields

Science.gov (United States)

Chanteur, G. M.; Le Contel, O.; Sahraoui, F.; Retino, A.; Mirioni, L.

2016-12-01

Multi-spacecraft missions like the ESA mission CLUSTER and the NASA mission MMS are essential to improve our understanding of physical processes in space plasmas. Several methods were designed in the 90's during the preparation phase of the CLUSTER mission to estimate gradients of physical fields from simultaneous multi-points measurements [1, 2]. Both CLUSTER and MMS involve four spacecraft with identical full scientific payloads including various sensors of electromagnetic fields and different type of particle detectors. In the standard methods described in [1, 2], which are presently in use, data from the four spacecraft have identical weights and the estimated gradients are most reliable when the tetrahedron formed by the four spacecraft is regular. There are three types of errors affecting the estimated gradients (see chapter 14 in [1]) : i) truncature errors are due to local non-linearity of spatial variations, ii) physical errors are due to instruments, and iii) geometrical errors are due to uncertainties on the positions of the spacecraft. An assessment of truncature errors for a given observation requires a theoretical model of the measured field. Instrumental errors can easily be taken into account for a given geometry of the cluster but are usually less than the geometrical errors which diverge quite fast when the tetrahedron flattens, a circumstance occurring twice per orbit of the cluster. Hence reliable gradients can be estimated only on part of the orbit. Reciprocal vectors of the tetrahedron were presented in chapter 4 of [1], they have the advantage over other methods to treat the four spacecraft symmetrically and to allow a theoretical analysis of the errors (see chapters 4 of [1] and 4 of [2]). We will present Generalized Reciprocal Vectors for weighted data and an optimization procedure to improve the reliability of the estimated gradients when the tetrahedron is not regular. A brief example using CLUSTER or MMS data will be given. This approach

High Speed Solution of Spacecraft Trajectory Problems Using Taylor Series Integration

Science.gov (United States)

Scott, James R.; Martini, Michael C.

2008-01-01

Taylor series integration is implemented in a spacecraft trajectory analysis code-the Spacecraft N-body Analysis Program (SNAP) - and compared with the code s existing eighth-order Runge-Kutta Fehlberg time integration scheme. Nine trajectory problems, including near Earth, lunar, Mars and Europa missions, are analyzed. Head-to-head comparison at five different error tolerances shows that, on average, Taylor series is faster than Runge-Kutta Fehlberg by a factor of 15.8. Results further show that Taylor series has superior convergence properties. Taylor series integration proves that it can provide rapid, highly accurate solutions to spacecraft trajectory problems.

Effort to recover SOHO spacecraft continue as investigation board focuses on most likely causes

Science.gov (United States)

1998-07-01

Meanwhile, the ESA/NASA investigation board concentrates its inquiry on three errors that appear to have led to the interruption of communications with SOHO on June 25. Officials remain hopeful that, based on ESA's successful recovery of the Olympus spacecraft after four weeks under similar conditions in 1991, recovery of SOHO may be possible. The SOHO Mission Interruption Joint ESA/NASA Investigation Board has determined that the first two errors were contained in preprogrammed command sequences executed on ground system computers, while the last error was a decision to send a command to the spacecraft in response to unexpected telemetry readings. The spacecraft is controlled by the Flight Operations Team, based at NASA's Goddard Space Flight Center, Greenbelt, MD. The first error was in a preprogrammed command sequence that lacked a command to enable an on-board software function designed to activate a gyro needed for control in Emergency Sun Reacquisition (ESR) mode. ESR mode is entered by the spacecraft in the event of anomalies. The second error, which was in a different preprogrammed command sequence, resulted in incorrect readings from one of the spacecraft's three gyroscopes, which in turn triggered an ESR. At the current stage of the investigation, the board believes that the two anomalous command sequences, in combination with a decision to send a command to SOHO to turn off a gyro in response to unexpected telemetry values, caused the spacecraft to enter a series of ESRs, and ultimately led to the loss of control. The efforts of the investigation board are now directed at identifying the circumstances that led to the errors, and at developing a recovery plan should efforts to regain contact with the spacecraft succeed. ESA and NASA engineers believe the spacecraft is currently spinning with its solar panels nearly edge-on towards the Sun, and thus not generating any power. Since the spacecraft is spinning around a fixed axis, as the spacecraft progresses

Passive radiative cooling of a HTS coil for attitude orbit control in micro-spacecraft

Science.gov (United States)

Inamori, Takaya; Ozaki, Naoya; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

2015-02-01

This paper proposes a novel radiative cooling system for a high temperature superconducting (HTS) coil for an attitude orbit control system in nano- and micro-spacecraft missions. These days, nano-spacecraft (1-10 kg) and micro-spacecraft (10-100 kg) provide space access to a broader range of spacecraft developers and attract interest as space development applications. In planetary and high earth orbits, most previous standard-size spacecraft used thrusters for their attitude and orbit control, which are not available for nano- and micro-spacecraft missions because of the strict power consumption, space, and weight constraints. This paper considers orbit and attitude control methods that use a superconducting coil, which interacts with on-orbit space plasmas and creates a propulsion force. Because these spacecraft cannot use an active cooling system for the superconducting coil because of their mass and power consumption constraints, this paper proposes the utilization of a passive radiative cooling system, in which the superconducting coil is thermally connected to the 3 K cosmic background radiation of deep space, insulated from the heat generation using magnetic holders, and shielded from the sun. With this proposed cooling system, the HTS coil is cooled to 60 K in interplanetary orbits. Because the system does not use refrigerators for its cooling system, the spacecraft can achieve an HTS coil with low power consumption, small mass, and low cost.

Dynamics and control of Lorentz-augmented spacecraft relative motion

CERN Document Server

Yan, Ye; Yang, Yueneng

2017-01-01

This book develops a dynamical model of the orbital motion of Lorentz spacecraft in both unperturbed and J2-perturbed environments. It explicitly discusses three kinds of typical space missions involving relative orbital control: spacecraft hovering, rendezvous, and formation flying. Subsequently, it puts forward designs for both open-loop and closed-loop control schemes propelled or augmented by the geomagnetic Lorentz force. These control schemes are entirely novel and represent a significantly departure from previous approaches.

Modeling and Simulation of Satellite Subsystems for End-to-End Spacecraft Modeling

National Research Council Canada - National Science Library

Schum, William K; Doolittle, Christina M; Boyarko, George A

2006-01-01

During the past ten years, the Air Force Research Laboratory (AFRL) has been simultaneously developing high-fidelity spacecraft payload models as well as a robust distributed simulation environment for modeling spacecraft subsystems...

Heat pipe applications for future Air Force spacecraft

International Nuclear Information System (INIS)

Mahefkey, T.; Barthelemy, R.R.

1980-01-01

This paper summarizes the envisioned, future usage of high and low temperature heat pipes in advanced Air Force spacecraft. Thermal control requirements for a variety of communications, surveillance, and space defense missions are forecast. Thermal design constraints implied by survivability to potential weapons effects are outlined. Applications of heat pipes to meet potential low and high power spacecraft mission requirements and envisioned design constraints are suggested. A brief summary of past Air Force sponsored heat pipe development efforts is presented and directions for future development outlined, including those applicable to advanced photovoltaic and nuclear power subsystem applications of heat pipes

Multi-kilowatt modularized spacecraft power processing system development

International Nuclear Information System (INIS)

Andrews, R.E.; Hayden, J.H.; Hedges, R.T.; Rehmann, D.W.

1975-07-01

A review of existing information pertaining to spacecraft power processing systems and equipment was accomplished with a view towards applicability to the modularization of multi-kilowatt power processors. Power requirements for future spacecraft were determined from the NASA mission model-shuttle systems payload data study which provided the limits for modular power equipment capabilities. Three power processing systems were compared to evaluation criteria to select the system best suited for modularity. The shunt regulated direct energy transfer system was selected by this analysis for a conceptual design effort which produced equipment specifications, schematics, envelope drawings, and power module configurations

In-Flight spacecraft magnetic field monitoring using scalar/vector gradiometry

DEFF Research Database (Denmark)

Primdahl, Fritz; Risbo, Torben; Merayo, José M.G.

2006-01-01

Earth magnetic field mapping from planetary orbiting satellites requires a spacecraft magnetic field environment control program combined with the deployment of the magnetic sensors on a boom in order to reduce the measurement error caused by the local spacecraft field. Magnetic mapping missions...... (Magsat, Oersted, CHAMP, SAC-C MMP and the planned ESA Swarm project) carry a vector magnetometer and an absolute scalar magnetometer for in-flight calibration of the vector magnetometer scale values and for monitoring of the inter-axes angles and offsets over time intervals from months to years...... sensors onboard the Oersted satellite. For Oersted, a large difference between the pre-flight determined spacecraft magnetic field and the in-flight estimate exists causing some concern about the general applicability of the dual sensors technique....

Spacecraft electrical power subsystem: Failure behavior, reliability, and multi-state failure analyses

International Nuclear Information System (INIS)

Kim, So Young; Castet, Jean-Francois; Saleh, Joseph H.

2012-01-01

This article investigates the degradation and failure behavior of spacecraft electrical power subsystem (EPS) on orbit. First, this work provides updated statistical reliability and multi-state failure analyses of spacecraft EPS and its different constituents, namely the batteries, the power distribution, and the solar arrays. The EPS is shown to suffer from infant mortality and to be a major driver of spacecraft unreliability. Over 25% of all spacecraft failures are the result of EPS failures. As a result, satellite manufacturers may wish to pursue targeted improvement to this subsystem, either through better testing or burn-in procedures, better design or parts selection, or additional redundancy. Second, this work investigates potential differences in the EPS degradation and failure behavior for spacecraft in low earth orbits (LEO) and geosynchronous orbits (GEO). This analysis was motivated by the recognition that the power/load cycles and the space environment are significantly different in LEO and GEO, and as such, they may result in different failure behavior for the EPS in these two types of orbits. The results indicate, and quantify the extent to which, the EPS fails differently in LEO and GEO, both in terms of frequency and severity of failure events. A casual summary of the findings can be stated as follows: the EPS fails less frequently but harder (with fatal consequences to the spacecraft) in LEO than in GEO.

FORTE spacecraft vibration mitigation. Final report

International Nuclear Information System (INIS)

Maly, J.R.

1996-02-01

This report documents work that was performed by CSA Engineering, Inc., for Los Alamos National Laboratory (LANL), to reduce vibrations of the FORTE spacecraft by retrofitting damped structural components into the spacecraft structure. The technical objective of the work was reduction of response at the location of payload components when the structure is subjected to the dynamic loading associated with launch and proto-qualification testing. FORTE is a small satellite that will be placed in orbit in 1996. The structure weighs approximately 425 lb, and is roughly 80 inches high and 40 inches in diameter. It was developed and built by LANL in conjunction with Sandia National Laboratories Albuquerque for the United States Department of Energy. The FORTE primary structure was fabricated primarily with graphite epoxy, using aluminum honeycomb core material for equipment decks and solar panel substrates. Equipment decks were bonded and bolted through aluminum mounting blocks to adjoining structure

Final results of the Resonance spacecraft calibration effort

Science.gov (United States)

Sampl, Manfred; Macher, Wolfgang; Gruber, Christian; Oswald, Thomas; Rucker, Helmut O.

2010-05-01

We report our dedicated analyses of electrical field sensors onboard the Resonance spacecraft with a focus on the high-frequency electric antennas. The aim of the Resonance mission is to investigate wave-particle interactions and plasma dynamics in the inner magnetosphere of the Earth, with a focus on phenomena occurring along the same field line and within the same flux tube of the Earth's magnetic field. Four spacecraft will be launched, in the middle of the next decade, to perform these observations and measurements. Amongst a variety of instruments and probes several low- and high-frequency electric sensors will be carried which can be used for simultaneous remote sensing and in-situ measurements. The high-frequency electric sensors consist of cylindrical antennas mounted on four booms extruded from the central body of the spacecraft. In addition, the boom rods themselves are used together with the these sensors for mutual impedance measurements. Due to the parasitic effects of the conducting spacecraft body the electrical antenna representations (effective length vector, capacitances) do not coincide with their physical representations. The analysis of the reception properties of these antennas is presented, along with a contribution to the understanding of their impairment by other objects; in particular the influence of large magnetic loop sensors is studied. In order to analyse the antenna system, we applied experimental and numerical methods. The experimental method, called rheometry, is essentially an electrolytic tank measurement, where a scaled-down spacecraft model is immersed into an electrolytic medium (water) with corresponding measurements of voltages at the antennas. The numerical method consists of a numerical solution of the underlying field equations by means of computer programs, which are based on wire-grid and patch-grid models. The experimental and numerical results show that parasitic effects of the antenna-spacecraft assembly alter the

Flight Plasma Diagnostics for High-Power, Solar-Electric Deep-Space Spacecraft

Science.gov (United States)

Johnson, Lee; De Soria-Santacruz Pich, Maria; Conroy, David; Lobbia, Robert; Huang, Wensheng; Choi, Maria; Sekerak, Michael J.

2018-01-01

NASA's Asteroid Redirect Robotic Mission (ARRM) project plans included a set of plasma and space environment instruments, the Plasma Diagnostic Package (PDP), to fulfill ARRM requirements for technology extensibility to future missions. The PDP objectives were divided into the classes of 1) Plasma thruster dynamics, 2) Solar array-specific environmental effects, 3) Plasma environmental spacecraft effects, and 4) Energetic particle spacecraft environment. A reference design approach and interface requirements for ARRM's PDP was generated by the PDP team at JPL and GRC. The reference design consisted of redundant single-string avionics located on the ARRM spacecraft bus as well as solar array, driving and processing signals from multiple copies of several types of plasma, effects, and environments sensors distributed over the spacecraft and array. The reference design sensor types were derived in part from sensors previously developed for USAF Research Laboratory (AFRL) plasma effects campaigns such as those aboard TacSat-2 in 2007 and AEHF-2 in 2012.

Particle Morphology and Elemental Composition of Smoke Generated by Overheating Common Spacecraft Materials

Science.gov (United States)

Meyer, Marit E.

2015-01-01

Fire safety in the indoor spacecraft environment is concerned with a unique set of fuels which are designed to not combust. Unlike terrestrial flaming fires, which often can consume an abundance of wood, paper and cloth, spacecraft fires are expected to be generated from overheating electronics consisting of flame resistant materials. Therefore, NASA prioritizes fire characterization research for these fuels undergoing oxidative pyrolysis in order to improve spacecraft fire detector design. A thermal precipitator designed and built for spacecraft fire safety test campaigns at the NASA White Sands Test Facility (WSTF) successfully collected an abundance of smoke particles from oxidative pyrolysis. A thorough microscopic characterization has been performed for ten types of smoke from common spacecraft materials or mixed materials heated at multiple temperatures using the following techniques: SEM, TEM, high resolution TEM, high resolution STEM and EDS. Resulting smoke particle morphologies and elemental compositions have been observed which are consistent with known thermal decomposition mechanisms in the literature and chemical make-up of the spacecraft fuels. Some conclusions about particle formation mechanisms are explored based on images of the microstructure of Teflon smoke particles and tar ball-like particles from Nomex fabric smoke.

A simplified Track Assembler I/O for the Muon Trigger Track Finder

CERN Document Server

Dallavalle, Gaetano-Marco; Genchev, Vladimir; Grandi, Claudio; Neumeister, Norbert; Porth, Paul; Rohringer, Herbert

1998-01-01

One of the architectural concerns in the present design of the Muon Trigger Track Finder ( MTTF) is the large number of inputs to the Track Assembler ( TA). In the TA block, input track segment pairs from many Extrapolation Units ( EU) are associated into tracks. The relative contribution of these inputs to the assembled tracks is studied with simulated track patterns for low and high pt muons over the entire eta, phi acceptance of the CMS barrel. A pruning of the EUs is proposed which does not alter the performance of the Track Finder and minimizes the interconnections between azimuthal wedges.

An Empirical Comparison between Two Recursive Filters for Attitude and Rate Estimation of Spinning Spacecraft

Science.gov (United States)

Harman, Richard R.

2006-01-01

The advantages of inducing a constant spin rate on a spacecraft are well known. A variety of science missions have used this technique as a relatively low cost method for conducting science. Starting in the late 1970s, NASA focused on building spacecraft using 3-axis control as opposed to the single-axis control mentioned above. Considerable effort was expended toward sensor and control system development, as well as the development of ground systems to independently process the data. As a result, spinning spacecraft development and their resulting ground system development stagnated. In the 1990s, shrinking budgets made spinning spacecraft an attractive option for science. The attitude requirements for recent spinning spacecraft are more stringent and the ground systems must be enhanced in order to provide the necessary attitude estimation accuracy. Since spinning spacecraft (SC) typically have no gyroscopes for measuring attitude rate, any new estimator would need to rely on the spacecraft dynamics equations. One estimation technique that utilized the SC dynamics and has been used successfully in 3-axis gyro-less spacecraft ground systems is the pseudo-linear Kalman filter algorithm. Consequently, a pseudo-linear Kalman filter has been developed which directly estimates the spacecraft attitude quaternion and rate for a spinning SC. Recently, a filter using Markley variables was developed specifically for spinning spacecraft. The pseudo-linear Kalman filter has the advantage of being easier to implement but estimates the quaternion which, due to the relatively high spinning rate, changes rapidly for a spinning spacecraft. The Markley variable filter is more complicated to implement but, being based on the SC angular momentum, estimates parameters which vary slowly. This paper presents a comparison of the performance of these two filters. Monte-Carlo simulation runs will be presented which demonstrate the advantages and disadvantages of both filters.

A Real Time Differential GPS Tracking System for NASA Sounding Rockets

Science.gov (United States)

Bull, Barton; Bauer, Frank (Technical Monitor)

2000-01-01

Sounding rockets are suborbital launch vehicles capable of carrying scientific payloads to several hundred miles in altitude. These missions return a variety of scientific data including: chemical makeup and physical processes taking place in the atmosphere, natural radiation surrounding the Earth, data on the Sun, stars, galaxies and many other phenomena. In addition, sounding rockets provide a reasonably economical means of conducting engineering tests for instruments and devices to be used on satellites and other spacecraft prior to their use in these more expensive missions. Typically around thirty of these rockets are launched each year, from established ranges at Wallops Island, Virginia; Poker Flat Research Range, Alaska; White Sands Missile Range, New Mexico and from a number of ranges outside the United States. Many times launches are conducted from temporary launch ranges in remote parts of the world requiring considerable expense to transport and operate tracking radars. In order to support these missions, an inverse differential GPS system has been developed. The flight system consists of a small, inexpensive receiver, a preamplifier and a wrap-around antenna. A rugged, compact, portable ground station extracts GPS data from the raw payload telemetry stream, performs a real time differential solution and graphically displays the rocket's path relative to a predicted trajectory plot. In addition to generating a real time navigation solution, the system has been used for payload recovery, timing, data timetagging, precise tracking of multiple payloads and slaving of optical tracking systems for over the horizon acquisition. This paper discusses, in detail, the flight and ground hardware, as well as data processing and operational aspects of the system, and provides evidence of the system accuracy.

Solar tracking system

Science.gov (United States)

Okandan, Murat; Nielson, Gregory N.

2016-07-12

Solar tracking systems, as well as methods of using such solar tracking systems, are disclosed. More particularly, embodiments of the solar tracking systems include lateral supports horizontally positioned between uprights to support photovoltaic modules. The lateral supports may be raised and lowered along the uprights or translated to cause the photovoltaic modules to track the moving sun.

Development, Demonstration and Validation of the Deep Space Orbit Determination Software Using Lunar Prospector Tracking Data

Directory of Open Access Journals (Sweden)

Eunji Lee

2017-09-01

Full Text Available The deep space orbit determination software (DSODS is a part of a flight dynamic subsystem (FDS for the Korean Pathfinder Lunar Orbiter (KPLO, a lunar exploration mission expected to launch after 2018. The DSODS consists of several sub modules, of which the orbit determination (OD module employs a weighted least squares algorithm for estimating the parameters related to the motion and the tracking system of the spacecraft, and subroutines for performance improvement and detailed analysis of the orbit solution. In this research, DSODS is demonstrated and validated at lunar orbit at an altitude of 100 km using actual Lunar Prospector tracking data. A set of a priori states are generated, and the robustness of DSODS to the a priori error is confirmed by the NASA planetary data system (PDS orbit solutions. Furthermore, the accuracy of the orbit solutions is determined by solution comparison and overlap analysis as about tens of meters. Through these analyses, the ability of the DSODS to provide proper orbit solutions for the KPLO are proved.

Temperature control of the Mariner class spacecraft - A seven mission summary.

Science.gov (United States)

Dumas, L. N.

1973-01-01

Mariner spacecraft have completed five missions of scientific investigation of the planets. Two additional missions are planned. A description of the thermal design of these seven spacecraft is given herein. The factors which have influenced the thermal design include the mission requirements and constraints, the flight environment, certain programmatic considerations and the experience gained as each mission is completed. These factors are reviewed and the impact of each on thermal design and developmental techniques is assessed. It is concluded that the flight success of these spacecraft indicates that adequate temperature control has been obtained, but that improvements in design data, hardware performance and analytical techniques are needed.

Evaluation of ion-sputtered molybdenum disulfide bearings for spacecraft gimbals

Science.gov (United States)

Loewenthal, S. H.; Chou, R. G.; Hopple, G. B.; Wenger, W. L.

1994-07-01

High-density, sputtered molybdenum disulfide films (MoS2) were investigated as lubricants for the next generation of spacecraft gimbal bearings where low torque signatures and long life are required. Low friction in a vacuum environment, virturally no out-gassing, insensitivity to low temperature, and radiation resistance of these lubricant films are valued in such applications. One hundred and twenty five thousand hours of acumulated bearing test time were obtained on 24 pairs of flight-quality bearings ion-sputtered with three types of advanced MoS2 films. Life tests were conducted in a vacuum over a simulated duty cycle for a space payload gimbal. Optimum retainer and ball material composition were investigated. Comparisions were made with test bearings lubricated with liquid space lubricants. Self-lubricating PTFE retainers were required for long life, i.e., greater than 40 million gimbal cycles. Bearings with polyimide retainers, silicon nitride ceramic balls, or steel balls sputtered with MoS2 film suffered early torque failure, irrespective of the type of race-sputtered MoS2 film. Failure generally resulted from excess film or retainer debris deposited in the ball track which tended to jam the bearing. Both grease lubricated and the better MoS2 film lubricated bearings produced long lives, although the torque with liquid lubricants was lower and less irregular.

Guidance and Navigation for Rendezvous and Proximity Operations with a Non-Cooperative Spacecraft at Geosynchronous Orbit

Science.gov (United States)

Barbee, Brent William; Carpenter, J. Russell; Heatwole, Scott; Markley, F. Landis; Moreau, Michael; Naasz, Bo J.; VanEepoel, John

2010-01-01

The feasibility and benefits of various spacecraft servicing concepts are currently being assessed, and all require that the servicer spacecraft perform rendezvous, proximity, and capture operations with the target spacecraft to be serviced. Many high-value spacecraft, which would be logical targets for servicing from an economic point of view, are located in geosynchronous orbit, a regime in which autonomous rendezvous and capture operations are not commonplace. Furthermore, existing GEO spacecraft were not designed to be serviced. Most do not have cooperative relative navigation sensors or docking features, and some servicing applications, such as de-orbiting of a non-functional spacecraft, entail rendezvous and capture with a spacecraft that may be non-functional or un-controlled. Several of these challenges have been explored via the design of a notional mission in which a nonfunctional satellite in geosynchronous orbit is captured by a servicer spacecraft and boosted into super-synchronous orbit for safe disposal. A strategy for autonomous rendezvous, proximity operations, and capture is developed, and the Orbit Determination Toolbox (ODTBX) is used to perform a relative navigation simulation to assess the feasibility of performing the rendezvous using a combination of angles-only and range measurements. Additionally, a method for designing efficient orbital rendezvous sequences for multiple target spacecraft is utilized to examine the capabilities of a servicer spacecraft to service multiple targets during the course of a single mission.

Nonlinearity-induced spacecraft tumbling

International Nuclear Information System (INIS)

Amos, A.K.

1994-01-01

An existing tumbling criterion for the dumbbell satellite in planar librations is reexamined and modified to reflect a recently identified tumbling mode associated with the horizontal attitude orientation. It is shown that for any initial attitude there exists a critical angular rate below which the motion is oscillatory and harmonic and beyond which a continuous tumbling will ensue. If the angular rate is at the critical value the spacecraft drifts towards the horizontal attitude from which a spontaneous periodic tumbling occurs

SSRPT (SSR Pointer Trackeer) for Cassini Mission Operations - A Ground Data Analysis Tool

Science.gov (United States)

Kan, E.

1998-01-01

Tracking the resources of the two redundant Solid State Recorders (SSR) is a necessary routine for Cassini spacecraft mission operations. Instead of relying on a full-fledged spacecraft hardware/software simulator to track and predict the SSR recording and playback pointer positions, a stand-alone SSR Pointer Tracker tool was developed as part of JPL's Multimission Spacecraft Analysis system.

Determination of Realistic Fire Scenarios in Spacecraft

Science.gov (United States)

Dietrich, Daniel L.; Ruff, Gary A.; Urban, David

2013-01-01

This paper expands on previous work that examined how large a fire a crew member could successfully survive and extinguish in the confines of a spacecraft. The hazards to the crew and equipment during an accidental fire include excessive pressure rise resulting in a catastrophic rupture of the vehicle skin, excessive temperatures that burn or incapacitate the crew (due to hyperthermia), carbon dioxide build-up or accumulation of other combustion products (e.g. carbon monoxide). The previous work introduced a simplified model that treated the fire primarily as a source of heat and combustion products and sink for oxygen prescribed (input to the model) based on terrestrial standards. The model further treated the spacecraft as a closed system with no capability to vent to the vacuum of space. The model in the present work extends this analysis to more realistically treat the pressure relief system(s) of the spacecraft, include more combustion products (e.g. HF) in the analysis and attempt to predict the fire spread and limiting fire size (based on knowledge of terrestrial fires and the known characteristics of microgravity fires) rather than prescribe them in the analysis. Including the characteristics of vehicle pressure relief systems has a dramatic mitigating effect by eliminating vehicle overpressure for all but very large fires and reducing average gas-phase temperatures.

Spacecraft-plasma-debris interaction in an ion beam shepherd mission

Science.gov (United States)

Cichocki, Filippo; Merino, Mario; Ahedo, Eduardo

2018-05-01

This paper presents a study of the interaction between a spacecraft, a plasma thruster plume and a free floating object, in the context of an active space debris removal mission based on the ion beam shepherd concept. The analysis is performed with the EP2PLUS hybrid code and includes the evaluation of the transferred force and torque to the target debris, its surface sputtering due to the impinging hypersonic ions, and the equivalent electric circuit of the spacecraft-plasma-debris interaction. The electric potential difference that builds up between the spacecraft and the debris, the ion backscattering and the backsputtering contamination of the shepherd satellite are evaluated for a nominal scenario. A sensitivity analysis is carried out to evaluate quantitatively the effects of electron thermodynamics, ambient plasma, heavy species collisions, and debris position.

Cassini Spacecraft In-Flight Swap to Backup Attitude Control Thrusters

Science.gov (United States)

Bates, David M.

2010-01-01

NASA's Cassini Spacecraft, launched on October 15th, 1997 and arrived at Saturn on June 30th, 2004, is the largest and most ambitious interplanetary spacecraft in history. In order to meet the challenging attitude control and navigation requirements of the orbit profile at Saturn, Cassini is equipped with a monopropellant thruster based Reaction Control System (RCS), a bipropellant Main Engine Assembly (MEA) and a Reaction Wheel Assembly (RWA). In 2008, after 11 years of reliable service, several RCS thrusters began to show signs of end of life degradation, which led the operations team to successfully perform the swap to the backup RCS system, the details and challenges of which are described in this paper. With some modifications, it is hoped that similar techniques and design strategies could be used to benefit other spacecraft.

Spacecraft Attitude Control in Hamiltonian Framework

DEFF Research Database (Denmark)

Wisniewski, Rafal

2000-01-01

The objective of this paper is to give a design scheme for attitude control algorithms of a generic spacecraft. Along with the system model formulated in the Hamilton's canonical form the algorithm uses information about a required potential energy and a dissipative term. The control action...

LP MOON SPACECRAFT ATTITUDE V1.0

Data.gov (United States)

National Aeronautics and Space Administration — The Lunar Prospector attitude data set consists of values for the spacecraft spin rate and spin axis orientation (attitude) as a function of time. These values are...

Modes of uncontrolled rotational motion of the Progress M-29M spacecraft

Science.gov (United States)

Belyaev, M. Yu.; Matveeva, T. V.; Monakhov, M. I.; Rulev, D. N.; Sazonov, V. V.

2018-01-01

We have reconstructed the uncontrolled rotational motion of the Progress M-29M transport cargo spacecraft in the single-axis solar orientation mode (the so-called sunward spin) and in the mode of the gravitational orientation of a rotating satellite. The modes were implemented on April 3-7, 2016 as a part of preparation for experiments with the DAKON convection sensor onboard the Progress spacecraft. The reconstruction was performed by integral statistical techniques using the measurements of the spacecraft's angular velocity and electric current from its solar arrays. The measurement data obtained in a certain time interval have been jointly processed using the least-squares method by integrating the equations of the spacecraft's motion relative to the center of mass. As a result of processing, the initial conditions of motion and parameters of the mathematical model have been estimated. The motion in the sunward spin mode is the rotation of the spacecraft with an angular velocity of 2.2 deg/s about the normal to the plane of solar arrays; the normal is oriented toward the Sun or forms a small angle with this direction. The duration of the mode is several orbit passes. The reconstruction has been performed over time intervals of up to 1 h. As a result, the actual rotational motion of the spacecraft relative to the Earth-Sun direction was obtained. In the gravitational orientation mode, the spacecraft was rotated about its longitudinal axis with an angular velocity of 0.1-0.2 deg/s; the longitudinal axis executed small oscillated relative to the local vertical. The reconstruction of motion relative to the orbital coordinate system was performed in time intervals of up to 7 h using only the angularvelocity measurements. The measurements of the electric current from solar arrays were used for verification.

MIDN: A spacecraft Micro-dosimeter mission

International Nuclear Information System (INIS)

Pisacane, V. L.; Ziegler, J. F.; Nelson, M. E.; Caylor, M.; Flake, D.; Heyen, L.; Youngborg, E.; Rosenfeld, A. B.; Cucinotta, F.; Zaider, M.; Dicello, J. F.

2006-01-01

MIDN (Micro-dosimetry instrument) is a payload on the MidSTAR-I spacecraft (Midshipman Space Technology Applications Research) under development at the United States Naval Academy. MIDN is a solid-state system being designed and constructed to measure Micro-dosimetric spectra to determine radiation quality factors for space environments. Radiation is a critical threat to the health of astronauts and to the success of missions in low-Earth orbit and space exploration. The system will consist of three separate sensors, one external to the spacecraft, one internal and one embedded in polyethylene. Design goals are mass <3 kg and power <2 W. The MidSTAR-I mission in 2006 will provide an opportunity to evaluate a preliminary version of this system. Its low power and mass makes it useful for the International Space Station and manned and unmanned interplanetary missions as a real-time system to assess and alert astronauts to enhanced radiation environments. (authors)

Close-Range Photogrammetry & Next Generation Spacecraft

Science.gov (United States)

Pappa, Richard S.

2002-01-01

NASA is focusing renewed attention on the topic of large, ultra-lightweight space structures, also known as 'gossamer' spacecraft. Nearly all of the details of the giant spacecraft are still to be worked out. But it's already clear that one of the most challenging aspects will be developing techniques to align and control these systems after they are deployed in space. A critical part of this process is creating new ground test methods to measure gossamer structures under stationary, deploying and vibrating conditions for validation of corresponding analytical predictions. In addressing this problem, I considered, first of all, the possibility of simply using conventional displacement or vibration sensor that could provide spatial measurements. Next, I turned my attention to photogrammetry, a method of determining the spatial coordinates of objects using photographs. The success of this research and development has convinced me that photogrammetry is the most suitable method to solve the gossamer measurement problem.

Cancellation of differential accelerations for the LISA spacecraft

International Nuclear Information System (INIS)

Bender, Peter L

2006-01-01

The three spacecraft of the Laser Interferometer Space Antenna will form a nearly equilateral triangle with nominal side lengths of 5 million km. However, the arm lengths and the corner angles will vary by very roughly 1% over 5-10 years. Part of this variation is due to the nature of Kepler orbits around the Sun. But Sweetser (2006 Astrodynamics 2005, Advances in the Astronautical Sciences vol 123 (San Diego, CA: Univelt Inc.) pp 693-712) has shown recently that differential secular accelerations due to the Earth for the three spacecraft prevent the minimal variations from being preserved for more than 2 or 3 years. Based on Sweetser's results, it appears possible to cancel out the differential secular acceleration due to the Earth by applying forces to the two proof masses in each spacecraft. The applied acceleration is at most 2.1 x 10 -9 m s -2 . However, the directions of the required accelerations would have substantial components along the sides of the triangle, and thus the amplitudes of the applied forces would have to have very low noise, even at frequencies down to below 0.1 mHz

Vibration Antiresonance Design for a Spacecraft Multifunctional Structure

Directory of Open Access Journals (Sweden)

Dong-Xu Li

2017-01-01

Full Text Available Spacecraft must withstand rigorous mechanical environment experiences such as acceleration, noise, vibration, and shock during the process of launching, satellite-vehicle separation, and so on. In this paper, a new spacecraft multifunctional structure concept designed by us is introduced. The multifunctional structure has the functions of not only load bearing, but also vibration reduction, energy source, thermal control, and so on, and we adopt a series of viscoelastic parts as connections between substructures. Especially in this paper, a vibration antiresonance design method is proposed to realize the vibration reduction. The complex zero-point equations of the vibration system are firstly established, and then the vibration antiresonance design for the system is achieved. For solving the difficulties due to viscoelastic characteristics of the connecting parts, we present the determining formulas to obtain the structural parameters, so that the complex zero-point equations can be satisfied. Numerical simulation and ground experiment demonstrate the correctness and effectiveness of the proposed method. This method can solve the structural vibration control problem under the function constraints of load bearing and energy supplying and will expand the performance of spacecraft functional modules.

Project Overview of the Naval Postgraduate School Spacecraft Architecture and Technology Demonstration Experiment

National Research Council Canada - National Science Library

Reuer, Charles

2001-01-01

The Naval Postgraduate School's current attempt at getting another spacecraft into orbit is focusing on Naval Postgraduate School Spacecraft Architecture and Technology Demonstration Experiment (NPSAT1...

New electromagnetic particle simulation code for the analysis of spacecraft-plasma interactions

International Nuclear Information System (INIS)

Miyake, Yohei; Usui, Hideyuki

2009-01-01

A novel particle simulation code, the electromagnetic spacecraft environment simulator (EMSES), has been developed for the self-consistent analysis of spacecraft-plasma interactions on the full electromagnetic (EM) basis. EMSES includes several boundary treatments carefully coded for both longitudinal and transverse electric fields to satisfy perfect conductive surface conditions. For the longitudinal component, the following are considered: (1) the surface charge accumulation caused by impinging or emitted particles and (2) the surface charge redistribution, such that the surface becomes an equipotential. For item (1), a special treatment has been adopted for the current density calculated around the spacecraft surface, so that the charge accumulation occurs exactly on the surface. As a result, (1) is realized automatically in the updates of the charge density and the electric field through the current density. Item (2) is achieved by applying the capacity matrix method. Meanwhile, the transverse electric field is simply set to zero for components defined inside and tangential to the spacecraft surfaces. This paper also presents the validation of EMSES by performing test simulations for spacecraft charging and peculiar EM wave modes in a plasma sheath.

Design, Simulation, Software Development, and Testing of a Compact Aircraft Tracking Payload for the CanX-7 Nanosatellite Mission

Science.gov (United States)

Bennett, Ian Graham

Automatic Dependent Surveillance-Broadcast (ADS-B) is quickly becoming the new standard for more efficient air traffic control, but as a satellite/ground-based hybrid system it faces limitations on its usefulness over oceans and remote areas. Tracking of aircraft from space presents many challenges that if overcome will greatly increase the safety and efficiency of commercial air travel in these areas. This thesis presents work performed to develop a flight-ready ADS-B receiver payload for the CanX-7 technology demonstration satellite. Work presented includes a simulation of payload performance and coverage area, the design and testing of a single-feed circularly polarized L-band antenna, the design of software to control the payload and manage its data, and verification of the performance of the hardware prior to integration with the satellite and launch. Also included is a short overview of results from the seven-month aircraft tracking campaign conducted with the spacecraft.

A computer program TRACK_P for studying proton tracks in PADC detectors

Directory of Open Access Journals (Sweden)

D. Nikezic

2016-01-01

Full Text Available A computer program for studying proton tracks in solid state nuclear track detectors was developed and described in this paper. The program was written in Fortran 90, with an additional tool for visualizing the track appearance as seen under the optical microscope in the transmission mode, which was written in the Python programming language. Measurable track parameters were determined and displayed in the application window and written in a data file. Three-dimensional representation of tracks was enabled. Examples of calculated tracks were also given in the present paper.

Persistent Aerial Tracking

KAUST Repository

Mueller, Matthias

2016-04-13

In this thesis, we propose a new aerial video dataset and benchmark for low altitude UAV target tracking, as well as, a photo-realistic UAV simulator that can be coupled with tracking methods. Our benchmark provides the rst evaluation of many state of-the-art and popular trackers on 123 new and fully annotated HD video sequences captured from a low-altitude aerial perspective. Among the compared trackers, we determine which ones are the most suitable for UAV tracking both in terms of tracking accuracy and run-time. We also present a simulator that can be used to evaluate tracking algorithms in real-time scenarios before they are deployed on a UAV "in the field", as well as, generate synthetic but photo-realistic tracking datasets with free ground truth annotations to easily extend existing real-world datasets. Both the benchmark and simulator will be made publicly available to the vision community to further research in the area of object tracking from UAVs. Additionally, we propose a persistent, robust and autonomous object tracking system for unmanned aerial vehicles (UAVs) called Persistent Aerial Tracking (PAT). A computer vision and control strategy is applied to a diverse set of moving objects (e.g. humans, animals, cars, boats, etc.) integrating multiple UAVs with a stabilized RGB camera. A novel strategy is employed to successfully track objects over a long period, by \\'handing over the camera\\' from one UAV to another. We integrate the complete system into an off-the-shelf UAV, and obtain promising results showing the robustness of our solution in real-world aerial scenarios.

Space Environments and Spacecraft Effects Organization Concept

Science.gov (United States)

Edwards, David L.; Burns, Howard D.; Miller, Sharon K.; Porter, Ron; Schneider, Todd A.; Spann, James F.; Xapsos, Michael

2012-01-01

The National Aeronautics and Space Administration (NASA) is embarking on a course to expand human presence beyond Low Earth Orbit (LEO) while also expanding its mission to explore the solar system. Destinations such as Near Earth Asteroids (NEA), Mars and its moons, and the outer planets are but a few of the mission targets. Each new destination presents an opportunity to increase our knowledge of the solar system and the unique environments for each mission target. NASA has multiple technical and science discipline areas specializing in specific space environments disciplines that will help serve to enable these missions. To complement these existing discipline areas, a concept is presented focusing on the development of a space environments and spacecraft effects (SENSE) organization. This SENSE organization includes disciplines such as space climate, space weather, natural and induced space environments, effects on spacecraft materials and systems and the transition of research information into application. This space environment and spacecraft effects organization will be composed of Technical Working Groups (TWG). These technical working groups will survey customers and users, generate products, and provide knowledge supporting four functional areas: design environments, engineering effects, operational support, and programmatic support. The four functional areas align with phases in the program mission lifecycle and are briefly described below. Design environments are used primarily in the mission concept and design phases of a program. Engineering effects focuses on the material, component, sub-system and system-level selection and the testing to verify design and operational performance. Operational support provides products based on real time or near real time space weather to mission operators to aid in real time and near-term decision-making. The programmatic support function maintains an interface with the numerous programs within NASA, other federal

Evaluation of Ultrafiltration for Spacecraft Water Reuse

Science.gov (United States)

Pickering, Karen D.; Wiesner, Mark R.

2001-01-01

Ultrafiltration is examined for use as the first stage of a primary treatment process for spacecraft wastewater. It is hypothesized that ultrafiltration can effectively serve as pretreatment for a reverse osmosis system, removing the majority of organic material in a spacecraft wastewater. However, it is believed that the interaction between the membrane material and the surfactant found in the wastewater will have a significant impact on the fouling of the ultrafiltration membrane. In this study, five different ultrafiltration membrane materials are examined for the filtration of wastewater typical of that expected to be produced onboard the International Space Station. Membranes are used in an unstirred batch cell. Flux, organic carbon rejection, and recovery from fouling are measured. The results of this evaluation will be used to select the most promising membranes for further study.

Time-dependent polar distribution of outgassing from a spacecraft

Science.gov (United States)

Scialdone, J. J.

1974-01-01

A technique has been developed to obtain a characterization of the self-generated environment of a spacecraft and its variation with time, angular position, and distance. The density, pressure, outgassing flux, total weight loss, and other important parameters were obtained from data provided by two mass measuring crystal microbalances, mounted back to back, at distance of 1 m from the spacecraft equivalent surface. A major outgassing source existed at an angular position of 300 deg to 340 deg, near the rocket motor, while the weakest source was at the antennas. The strongest source appeared to be caused by a material diffusion process which produced a directional density at 1 m distance of about 1.6 x 10 to the 11th power molecules/cu cm after 1 hr in vacuum and decayed to 1.6 x 10 to the 9th power molecules/cu cm after 200 hr. The total average outgassing flux at the same distance and during the same time span changed from 1.2 x 10 to the minus 7th power to 1.4 x to the minus 10th power g/sq cm/s. These values are three times as large at the spacecraft surface. Total weight loss was 537 g after 10 hr and about 833 g after 200 hr. Self-contamination of the spacecraft was equivalent to that in orbit at about 300-km altitude.

Materials and structures technology insertion into spacecraft systems: Successes and challenges

Science.gov (United States)

Rawal, Suraj

2018-05-01

Over the last 30 years, significant advancements have led to the use of multifunctional materials and structures technologies in spacecraft systems. This includes the integration of adaptive structures, advanced composites, nanotechnology, and additive manufacturing technologies. Development of multifunctional structures has been directly influenced by the implementation of processes and tools for adaptive structures pioneered by Prof. Paolo Santini. Multifunctional materials and structures incorporating non-structural engineering functions such as thermal, electrical, radiation shielding, power, and sensors have been investigated. The result has been an integrated structure that offers reduced mass, packaging volume, and ease of integration for spacecraft systems. Current technology development efforts are being conducted to develop innovative multifunctional materials and structures designs incorporating advanced composites, nanotechnology, and additive manufacturing. However, these efforts offer significant challenges in the qualification and acceptance into spacecraft systems. This paper presents a brief overview of the technology development and successful insertion of advanced material technologies into spacecraft structures. Finally, opportunities and challenges to develop and mature next generation advanced materials and structures are presented.

GEOS-C altimeter attitude bias error correction. [gate-tracking radar

Science.gov (United States)

Marini, J. W.

1974-01-01

A pulse-limited split-gate-tracking radar altimeter was flown on Skylab and will be used aboard GEOS-C. If such an altimeter were to employ a hypothetical isotropic antenna, the altimeter output would be independent of spacecraft orientation. To reduce power requirements the gain of the altimeter antenna proposed is increased to the point where its beamwidth is only a few degrees. The gain of the antenna consequently varies somewhat over the pulse-limited illuminated region of the ocean below the altimeter, and the altimeter output varies with antenna orientation. The error introduced into the altimeter data is modeled empirically, but close agreements with the expected errors was not realized. The attitude error effects expected with the GEOS-C altimeter are modelled using a form suggested by an analytical derivation. The treatment is restricted to the case of a relatively smooth sea, where the height of the ocean waves are small relative to the spatial length (pulse duration times speed of light) of the transmitted pulse.

Stabilization of rotational motion with application to spacecraft attitude control

DEFF Research Database (Denmark)

Wisniewski, Rafal

2000-01-01

for global stabilization of a rotary motion. Along with a model of the system formulated in the Hamilton's canonical from the algorithm uses information about a required potential energy and a dissipation term. The control action is the sum of the gradient of the potential energy and the dissipation force......The objective of this paper is to develop a control scheme for stabilization of a hamiltonian system. The method generalizes the results available in the literature on motion control in the Euclidean space to an arbitrary differrential manifol equipped with a metric. This modification is essencial...... on a Riemannian manifold. The Lyapnov stability theory is adapted and reformulated to fit to the new framework of Riemannian manifolds. Toillustrate the results a spacecraft attitude control problem is considered. Firstly, a global canonical representation for the spacecraft motion is found, then three spacecraft...

Stabilization of rotational motion with application to spacecraft attitude control

DEFF Research Database (Denmark)

Wisniewski, Rafal

2001-01-01

for global stabilization of a rotary motion. Along with a model of the system formulated in the Hamilton's canonical from the algorithm uses information about a required potential energy and a dissipation term. The control action is the sum of the gradient of the potential energy and the dissipation force......The objective of this paper is to develop a control scheme for stabilization of a hamiltonian system. The method generalizes the results available in the literature on motion control in the Euclidean space to an arbitrary differrential manifol equipped with a metric. This modification is essencial...... on a Riemannian manifold. The Lyapnov stability theory is adapted and reformulated to fit to the new framework of Riemannian manifolds. Toillustrate the results a spacecraft attitude control problem is considered. Firstly, a global canonical representation for the spacecraft motion is found, then three spacecraft...

Kalman Filter Track Fits and Track Breakpoint Analysis

CERN Document Server

Astier, Pierre; Cousins, R D; Letessier-Selvon, A A; Popov, B A; Vinogradova, T G; Astier, Pierre; Cardini, Alessandro; Cousins, Robert D.; Letessier-Selvon, Antoine; Popov, Boris A.; Vinogradova, Tatiana

2000-01-01

We give an overview of track fitting using the Kalman filter method in the NOMAD detector at CERN, and emphasize how the wealth of by-product information can be used to analyze track breakpoints (discontinuities in track parameters caused by scattering, decay, etc.). After reviewing how this information has been previously exploited by others, we describe extensions which add power to breakpoint detection and characterization. We show how complete fits to the entire track, with breakpoint parameters added, can be easily obtained from the information from unbroken fits. Tests inspired by the Fisher F-test can then be used to judge breakpoints. Signed quantities (such as change in momentum at the breakpoint) can supplement unsigned quantities such as the various chisquares. We illustrate the method with electrons from real data, and with Monte Carlo simulations of pion decays.

Framework conditions for tracking electricity in Europe. E-TRACK WP2 report

International Nuclear Information System (INIS)

Lise, W.; Boots, M.G.; De Joode, J.; Ten Donkelaar, M.; Timpe, C.; Vrolijk, C.

2006-03-01

The analysis of this report shows that context matters for tracking generation attributes. On the one hand, there are factors that enable the introduction of tracking, like previous experiences with green certificates. Some Member States have already gained experience with tracking generation attributes, which is required to disclose the generation mix to the consumer. On the other hand, there are factors that are making the introduction of tracking generation attributes in Europe more difficult, like the widely varying initiatives among Member States with respect to legislation on GOs and disclosure. Also the market conditions can be of influence. The varying degree of market opening matters, because the usefulness of tracking is lower in a market where a customer cannot switch among suppliers. The amount of electricity traded makes it difficult to link generation to consumption under contract-based tracking, while this is of no concern under certificate-based tracking. One of the ways towards overcoming the aforementioned barriers is harmonisation of schemes for tracking generation attributes

Spacecraft computer technology at Southwest Research Institute

Science.gov (United States)

Shirley, D. J.

1993-01-01

Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-Earth-orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. We describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. Because of their reduced size, weight, and power, these newer designs are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCM's. Long term plans include development of whole-core processors on one or two MCM's.

Investigation of tenuous plasma environment using Active Spacecraft Potential Control (ASPOC) on Magnetospheric Multiscale (MMS) Mission

Science.gov (United States)

Nakamura, Rumi; Jeszenszky, Harald; Torkar, Klaus; Andriopoulou, Maria; Fremuth, Gerhard; Taijmar, Martin; Scharlemann, Carsten; Svenes, Knut; Escoubet, Philippe; Prattes, Gustav; Laky, Gunter; Giner, Franz; Hoelzl, Bernhard

2015-04-01

The NASA's Magnetospheric Multiscale (MMS) Mission is planned to be launched on March 12, 2015. The scientific objectives of the MMS mission are to explore and understand the fundamental plasma physics processes of magnetic reconnection, particle acceleration and turbulence in the Earth's magnetosphere. The region of scientific interest of MMS is in a tenuous plasma environment where the positive spacecraft potential reaches an equilibrium at several tens of Volts. An Active Spacecraft Potential Control (ASPOC) instrument neutralizes the spacecraft potential by releasing positive charge produced by indium ion emitters. ASPOC thereby reduces the potential in order to improve the electric field and low-energy particle measurement. The method has been successfully applied on other spacecraft such as Cluster and Double Star. Two ASPOC units are present on each of the MMS spacecraft. Each unit contains four ion emitters, whereby one emitter per instrument is operated at a time. ASPOC for MMS includes new developments in the design of the emitters and the electronics enabling lower spacecraft potentials, higher reliability, and a more uniform potential structure in the spacecraft's sheath compared to previous missions. Model calculations confirm the findings from previous applications that the plasma measurements will not be affected by the beam's space charge. A perfectly stable spacecraft potential precludes the utilization of the spacecraft as a plasma probe, which is a conventional technique used to estimate ambient plasma density from the spacecraft potential. The small residual variations of the potential controlled by ASPOC, however, still allow to determine ambient plasma density by comparing two closely separated spacecraft and thereby reconstructing the uncontrolled potential variation from the controlled potential. Regular intercalibration of controlled and uncontrolled potentials is expected to increase the reliability of this new method.

Tracks: Nurses and the Tracking Network

Centers for Disease Control (CDC) Podcasts

2012-06-06

This podcast highlights the utility of the National Environmental Public Health Tracking Network for nurses in a variety of work settings. It features commentary from the American Nurses Association and includes stories from a public health nurse in Massachusetts.  Created: 6/6/2012 by National Center for Environmental Health (NCEH)/Division of Environmental Hazards and Health Effects (DEHHE)/Environmental Health Tracking Branch (EHTB).   Date Released: 6/6/2012.

Decontaminate feature for tracking: adaptive tracking via evolutionary feature subset

Science.gov (United States)

Liu, Qiaoyuan; Wang, Yuru; Yin, Minghao; Ren, Jinchang; Li, Ruizhi

2017-11-01

Although various visual tracking algorithms have been proposed in the last 2-3 decades, it remains a challenging problem for effective tracking with fast motion, deformation, occlusion, etc. Under complex tracking conditions, most tracking models are not discriminative and adaptive enough. When the combined feature vectors are inputted to the visual models, this may lead to redundancy causing low efficiency and ambiguity causing poor performance. An effective tracking algorithm is proposed to decontaminate features for each video sequence adaptively, where the visual modeling is treated as an optimization problem from the perspective of evolution. Every feature vector is compared to a biological individual and then decontaminated via classical evolutionary algorithms. With the optimized subsets of features, the "curse of dimensionality" has been avoided while the accuracy of the visual model has been improved. The proposed algorithm has been tested on several publicly available datasets with various tracking challenges and benchmarked with a number of state-of-the-art approaches. The comprehensive experiments have demonstrated the efficacy of the proposed methodology.

Elastic tracking versus neural network tracking for very high multiplicity problems

International Nuclear Information System (INIS)

Harlander, M.; Gyulassy, M.

1991-04-01

A new Elastic Tracking (ET) algorithm is proposed for finding tracks in very high multiplicity and noisy environments. It is based on a dynamical reinterpretation and generalization of the Radon transform and is related to elastic net algorithms for geometrical optimization. ET performs an adaptive nonlinear fit to noisy data with a variable number of tracks. Its numerics is more efficient than that of the traditional Radon or Hough transform method because it avoids binning of phase space and the costly search for valid minima. Spurious local minima are avoided in ET by introducing a time-dependent effective potential. The method is shown to be very robust to noise and measurement error and extends tracking capabilities to much higher track densities than possible via local road finding or even the novel Denby-Peterson neural network tracking algorithms. 12 refs., 2 figs

Ionospheric response to the shock and acoustic waves excited by the launch of the Shenzhou 10 spacecraft

Science.gov (United States)

Ding, Feng; Wan, Weixing; Mao, Tian; Wang, Min; Ning, Baiqi; Zhao, Biqiang; Xiong, Bo

2014-05-01

We used a dense GPS network in China to track the ionospheric response to waves excited by the launch of the rocket that carried Shenzhou 10 spacecraft on 11 June 2013. The long-distance propagation of shock and acoustic waves were observed on both sides of the rocket's trajectory. On the southern side, the wave structures (characterized by a horizontal extension of ~1400 km and initial amplitudes of 0.3 total electron content unit (TECU) and 0.1 TECU for the shock and acoustic waves, respectively), traveled southwestward a distance of ~1500 km at mean velocities of 1011 m s-1 and 709 m s-1, respectively. On the northern side, northward propagating waves were seen to travel a distance of ~600 km with much smaller amplitudes of less than 0.05 TECU. Subsequent waves with amplitudes of less than 0.02 TECU could also be seen. Clear wave structures were found at a distance of ~600-2000 km from launch site.

Spacecraft rendezvous and docking

DEFF Research Database (Denmark)

Jørgensen, John Leif

1999-01-01

The phenomenons and problems encountered when a rendezvous manoeuvre, and possible docking, of two spacecrafts has to be performed, have been the topic for numerous studies, and, details of a variety of scenarios has been analysed. So far, all solutions that has been brought into realization has...... been based entirely on direct human supervision and control. This paper describes a vision-based system and methodology, that autonomously generates accurate guidance information that may assist a human operator in performing the tasks associated with both the rendezvous and docking navigation...

Spacecraft exploration of asteroids

International Nuclear Information System (INIS)

Veverka, J.; Langevin, Y.; Farquhar, R.; Fulchignoni, M.

1989-01-01

After two decades of spacecraft exploration, we still await the first direct investigation of an asteroid. This paper describes how a growing international interest in the solar system's more primitive bodies should remedy this. Plans are under way in Europe for a dedicated asteroid mission (Vesta) which will include multiple flybys with in situ penetrator studies. Possible targets include 4 Vesta, 8 Flora and 46 Hestia; launch its scheduled for 1994 or 1996. In the United States, NASA plans include flybys of asteroids en route to outer solar system targets

Proton induced target fragmentation studies on solid state nuclear track detectors using Carbon radiators

Science.gov (United States)

Szabó, J.; Pálfalvi, J. K.; Strádi, A.; Bilski, P.; Swakoń, J.; Stolarczyk, L.

2018-04-01

One of the limiting factors of an astronaut's career is the dose received from space radiation. High energy protons, being the main components of the complex radiation field present on a spacecraft, give a significant contribution to the dose. To investigate the behavior of solid state nuclear track detectors (SSNTDs) if they are irradiated by such particles, SSNTD stacks containing carbon blocks were exposed to high energy proton beams (70, 100, 150 and 230 MeV) at the Proteus cyclotron, IFJ PAN -Krakow. The incident protons cannot be detected directly; however, tracks of secondary particles, recoils and fragments of the constituent atoms of the detector material and of the carbon radiator are formed. It was found that as the proton energy increases, the number of tracks induced in the PADC material by secondary particles decreases. From the measured geometrical parameters of the tracks the linear energy transfer (LET) spectrum and the dosimetric quantities were determined, applying appropriate calibration. In the LET spectra the LET range of the most important secondary particles could be identified and their abundance showed differences in the spectra if the detectors were short or long etched. The LET spectra obtained on the SSNTDs irradiated by protons were compared to LET spectra of detectors flown on the International Space Station (ISS): they were quite similar, resulting in a quality factor difference of only 5%. Thermoluminescent detectors (TLDs) were applied in each case to measure the dose from primary protons and other lower LET particles present in space. Comparing and analyzing the results of the TLD and SSNTD measurements, it was obtained that proton induced target fragments contributed to the total absorbed dose in 3.2% and to the dose equivalent in 14.2% in this particular space experiment.

Artificial Neural Network Based Mission Planning Mechanism for Spacecraft

Science.gov (United States)

Li, Zhaoyu; Xu, Rui; Cui, Pingyuan; Zhu, Shengying

2018-04-01

The ability to plan and react fast in dynamic space environments is central to intelligent behavior of spacecraft. For space and robotic applications, many planners have been used. But it is difficult to encode the domain knowledge and directly use existing techniques such as heuristic to improve the performance of the application systems. Therefore, regarding planning as an advanced control problem, this paper first proposes an autonomous mission planning and action selection mechanism through a multiple layer perceptron neural network approach to select actions in planning process and improve efficiency. To prove the availability and effectiveness, we use autonomous mission planning problems of the spacecraft, which is a sophisticated system with complex subsystems and constraints as an example. Simulation results have shown that artificial neural networks (ANNs) are usable for planning problems. Compared with the existing planning method in EUROPA, the mechanism using ANNs is more efficient and can guarantee stable performance. Therefore, the mechanism proposed in this paper is more suitable for planning problems of spacecraft that require real time and stability.

Space tribology: its role in spacecraft mechanisms

International Nuclear Information System (INIS)

Roberts, E W

2012-01-01

The subject of tribology encompasses the friction, wear and lubrication of mechanical components such as bearings and gears. Tribological practices are aimed at ensuring that such components operate with high efficiency (low friction) and achieve long lives. On spacecraft mechanisms the route to achieving these goals brings its own unique challenges. This review describes the problems posed by the space environment, the types of tribological component used on spacecraft and the approaches taken to their lubrication. It is shown that in many instances lubrication needs can be met by synthetic oils having exceedingly low volatilities, but that at temperature extremes the only means of reducing friction and wear is by solid lubrication. As the demands placed on space engineering increase, innovatory approaches will be needed to solve future tribological problems. The direction that future developments might take is anticipated and discussed.

Large Scale Experiments on Spacecraft Fire Safety

DEFF Research Database (Denmark)

Urban, David L.; Ruff, Gary A.; Minster, Olivier

2012-01-01

-based microgravity facilities or has been limited to very small fuel samples. Still, the work conducted to date has shown that fire behaviour in low-gravity is very different from that in normal-gravity, with differences observed for flammability limits, ignition delay, flame spread behaviour, flame colour and flame......Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due...... to the complexity, cost and risk associ-ated with operating a long duration fire safety experiment of a relevant size in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. The entire body of low-gravity fire research has either been conducted in short duration ground...

Galileo spacecraft power management and distribution system

International Nuclear Information System (INIS)

Detwiler, R.C.; Smith, R.L.

1990-01-01

It has been twelve years since two Voyager spacecraft began the direct route to the outer planets. In October 1989 a single Galileo spacecraft started the return to Jupiter. Conceived as a simple Voyager look-alike, the Galileo power management and distribution (PMAD) system has undergone many iterations in configuration. Major changes to the PMAD resulted from dual spun slip ring limitations, variations in launch vehicle thrust capabilities, and launch delays. Lack of an adequate launch vehicle for an interplanetary mission of Galileo's size has resulted in an extremely long flight duration. A Venus-Earth-Earth Gravity Assist (VEEGA) tour, vital to attain the required energy, results in a 6 year trip to Jupiter and its moons. This paper provides a description of the Galileo PMAD and documents the design drivers that established the final as-built hardware

Methodology for Developing a Probabilistic Risk Assessment Model of Spacecraft Rendezvous and Dockings

Science.gov (United States)

Farnham, Steven J., II; Garza, Joel, Jr.; Castillo, Theresa M.; Lutomski, Michael

2011-01-01

In 2007 NASA was preparing to send two new visiting vehicles carrying logistics and propellant to the International Space Station (ISS). These new vehicles were the European Space Agency s (ESA) Automated Transfer Vehicle (ATV), the Jules Verne, and the Japanese Aerospace and Explorations Agency s (JAXA) H-II Transfer Vehicle (HTV). The ISS Program wanted to quantify the increased risk to the ISS from these visiting vehicles. At the time, only the Shuttle, the Soyuz, and the Progress vehicles rendezvoused and docked to the ISS. The increased risk to the ISS was from an increase in vehicle traffic, thereby, increasing the potential catastrophic collision during the rendezvous and the docking or berthing of the spacecraft to the ISS. A universal method of evaluating the risk of rendezvous and docking or berthing was created by the ISS s Risk Team to accommodate the increasing number of rendezvous and docking or berthing operations due to the increasing number of different spacecraft, as well as the future arrival of commercial spacecraft. Before the first docking attempt of ESA's ATV and JAXA's HTV to the ISS, a probabilistic risk model was developed to quantitatively calculate the risk of collision of each spacecraft with the ISS. The 5 rendezvous and docking risk models (Soyuz, Progress, Shuttle, ATV, and HTV) have been used to build and refine the modeling methodology for rendezvous and docking of spacecrafts. This risk modeling methodology will be NASA s basis for evaluating the addition of future ISS visiting spacecrafts hazards, including SpaceX s Dragon, Orbital Science s Cygnus, and NASA s own Orion spacecraft. This paper will describe the methodology used for developing a visiting vehicle risk model.

Printable Spacecraft: Flexible Electronic Platforms for NASA Missions. Phase One

Science.gov (United States)

Short, Kendra (Principal Investigator); Van Buren, David (Principal Investigator)

2012-01-01

Atmospheric confetti. Inchworm crawlers. Blankets of ground penetrating radar. These are some of the unique mission concepts which could be enabled by a printable spacecraft. Printed electronics technology offers enormous potential to transform the way NASA builds spacecraft. A printed spacecraft's low mass, volume and cost offer dramatic potential impacts to many missions. Network missions could increase from a few discrete measurements to tens of thousands of platforms improving areal density and system reliability. Printed platforms could be added to any prime mission as a low-cost, minimum resource secondary payload to augment the science return. For a small fraction of the mass and cost of a traditional lander, a Europa flagship mission might carry experimental printed surface platforms. An Enceladus Explorer could carry feather-light printed platforms to release into volcanic plumes to measure composition and impact energies. The ability to print circuits directly onto a variety of surfaces, opens the possibility of multi-functional structures and membranes such as "smart" solar sails and balloons. The inherent flexibility of a printed platform allows for in-situ re-configurability for aerodynamic control or mobility. Engineering telemetry of wheel/soil interactions are possible with a conformal printed sensor tape fit around a rover wheel. Environmental time history within a sample return canister could be recorded with a printed sensor array that fits flush to the interior of the canister. Phase One of the NIAC task entitled "Printable Spacecraft" investigated the viability of printed electronics technologies for creating multi-functional spacecraft platforms. Mission concepts and architectures that could be enhanced or enabled with this technology were explored. This final report captures the results and conclusions of the Phase One study. First, the report presents the approach taken in conducting the study and a mapping of results against the proposed

The SPQR experiment: detecting damage to orbiting spacecraft with ground-based telescopes

Science.gov (United States)

Paolozzi, Antonio; Porfilio, Manfredi; Currie, Douglas G.; Dantowitz, Ronald F.

2007-09-01

The objective of the Specular Point-like Quick Reference (SPQR) experiment was to evaluate the possibility of improving the resolution of ground-based telescopic imaging of manned spacecraft in orbit. The concept was to reduce image distortions due to atmospheric turbulence by evaluating the Point Spread Function (PSF) of a point-like light reference and processing the spacecraft image accordingly. The target spacecraft was the International Space Station (ISS) and the point-like reference was provided by a laser beam emitted by the ground station and reflected back to the telescope by a Cube Corner Reflector (CCR) mounted on an ISS window. The ultimate objective of the experiment was to demonstrate that it is possible to image spacecraft in Low Earth Orbit (LEO) with a resolution of 20 cm, which would have probably been sufficient to detect the damage which caused the Columbia disaster. The experiment was successfully performed from March to May 2005. The paper provides an overview of the SPQR experiment.

Protection of surface assets on Mars from wind blown jettisoned spacecraft components

Science.gov (United States)

Paton, Mark

2017-07-01

Jettisoned Entry, Descent and Landing System (EDLS) hardware from landing spacecraft have been observed by orbiting spacecraft, strewn over the Martian surface. Future Mars missions that land spacecraft close to prelanded assets will have to use a landing architecture that somehow minimises the possibility of impacts from these jettisoned EDLS components. Computer modelling is used here to investigate the influence of wind speed and direction on the distribution of EDLS components on the surface. Typical wind speeds encountered in the Martian Planetary Boundary Layer (PBL) were found to be of sufficient strength to blow items having a low ballistic coefficient, i.e. Hypersonic Inflatable Aerodynamic Decelerators (HIADs) or parachutes, onto prelanded assets even when the lander itself touches down several kilometres away. Employing meteorological measurements and careful characterisation of the Martian PBL, e.g. appropriate wind speed probability density functions, may then benefit future spacecraft landings, increase safety and possibly help reduce the delta v budget for Mars landers that rely on aerodynamic decelerators.

Trajectories for spacecraft encounters with Comet Honda-Mrkos-Pajdusakova in 1996

Science.gov (United States)

Dunham, David W.; Jen, Shao-Chiang; Farquhar, Robert W.

1989-01-01

Early in 1996, the relatively bright short-period Comet Honda-Mrkos-Pajdusakova (HMP) will pass only 0.17 astronomical unit from the earth, providing both an unusually favorable apparition for ground-based observers and an opportunity for a spacecraft to reach Comet HMP on relatively low-energy trajectories. The Japanense Institute of Space and Astronautical Sciences Sakigake spacecraft is expected to fly by Comet HMP on February 3, 1996, after utilizing four earth swingbys to modify its orbit. If the camera on the ESA Giotto spacecraft is inoperable, Giotto may also be sent to Comet HMP. In addition, 1-year earth-return trajectories to Comet HMP are described, along with some that can be extended to encounter Comet Giacobini-Zinner in 1998.

Injection and propagation of a nonrelativistic electron beam and spacecraft charging

International Nuclear Information System (INIS)

Okuda, H.; Berchem, J.

1987-05-01

Two-dimensional numerical simulations have been carried out in order to study the injection and propagation of a nonrelativistic electron beam from a spacecraft into a fully ionized plasma in a magnetic field. Contrary to the earlier results in one-dimension, a high density electron beam whose density is comparable to the ambient density can propagate into a plasma. A strong radial electric field resulting from the net charges in the beam causes the beam electrons to spread radially reducing the beam density. When the injection current exceeds the return current, significant charging of the spacecraft is observed along with the reflection of the injected electrons back to the spacecraft. Recent data on the electron beam injection from the Spacelab 1 (SEPAC) are discussed

Multi-objective optimisation for spacecraft design for demise and survivability

OpenAIRE

Trisolini, Mirko; Colombo, Camilla; Lewis, Hugh

2017-01-01

The paper presents the development of a multi-objective optimisation framework to study the effects that preliminary design choices have on the demisability and the survivability of a spacecraft. Building a spacecraft such that most of it will demise during the re-entry through design-for-demise strategies may lead to design that are more vulnerable to space debris impacts, thus compromising the reliability of the mission. The two models developed to analyse the demisability and the survivabi...

Neural network tracking and extension of positive tracking periods

Science.gov (United States)

Hanan, Jay C.; Chao, Tien-Hsin; Moreels, Pierre

2004-04-01

Feature detectors have been considered for the role of supplying additional information to a neural network tracker. The feature detector focuses on areas of the image with significant information. Basically, if a picture says a thousand words, the feature detectors are looking for the key phrases (keypoints). These keypoints are rotationally invariant and may be matched across frames. Application of these advanced feature detectors to the neural network tracking system at JPL has promising potential. As part of an ongoing program, an advanced feature detector was tested for augmentation of a neural network based tracker. The advance feature detector extended tracking periods in test sequences including aircraft tracking, rover tracking, and simulated Martian landing. Future directions of research are also discussed.

Trajectories of inner and outer heliospheric spacecraft: Predicted through 1999

Science.gov (United States)

Parthasarathy, R.; King, Joseph H.

1991-01-01

Information is presented in tabular and graphical form on the trajectories of the international fleet of spacecraft that will be probing the far reaches of the heliosphere during the 1990s. In particular, the following spacecraft are addressed: Pioneer 10 and 11, Pioneer Venus Orbiter (PVO), Voyager 1 and 2, Galileo, Ulysses, Suisei, Sakigake, Giotto, International Cometary Explorer (ICE), and Interplanetary Monitoring Platform 8 (IMP 8). Yearly resolution listing of position information in inertial space are given for Pioneer and Voyager spacecraft from the times of their launches in the 1970s. One series of plots shows the radial distances, latitudes, and longitudes of the Pioneers and Voyagers. The solar ecliptic inertial coordinate system is used. In this system, the Z axis is normal to the ecliptic plane and the X axis is towards the first point of Aries (from Sun to Earth on the vernal equinox).

Electromagnetic Dissociation and Spacecraft Electronics Damage

Science.gov (United States)

Norbury, John W.

2016-01-01

When protons or heavy ions from galactic cosmic rays (GCR) or solar particle events (SPE) interact with target nuclei in spacecraft, there can be two different types of interactions. The more familiar strong nuclear interaction often dominates and is responsible for nuclear fragmentation in either the GCR or SPE projectile nucleus or the spacecraft target nucleus. (Of course, the proton does not break up, except possibly to produce pions or other hadrons.) The less familiar, second type of interaction is due to the very strong electromagnetic fields that exist when two charged nuclei pass very close to each other. This process is called electromagnetic dissociation (EMD) and primarily results in the emission of neutrons, protons and light ions (isotopes of hydrogen and helium). The cross section for particle production is approximately defined as the number of particles produced in nucleus-nucleus collisions or other types of reactions. (There are various kinematic and other factors which multiply the particle number to arrive at the cross section.) Strong, nuclear interactions usually dominate the nuclear reactions of most interest that occur between GCR and target nuclei. However, for heavy nuclei (near Fe and beyond) at high energy the EMD cross section can be much larger than the strong nuclear interaction cross section. This paper poses a question: Are there projectile or target nuclei combinations in the interaction of GCR or SPE where the EMD reaction cross section plays a dominant role? If the answer is affirmative, then EMD mechanisms should be an integral part of codes that are used to predict damage to spacecraft electronics. The question can become more fine-tuned and one can ask about total reaction cross sections as compared to double differential cross sections. These issues will be addressed in the present paper.

Quaternion Feedback Control for Rigid-body Spacecraft

DEFF Research Database (Denmark)

Jensen, Hans-Christian Becker; Wisniewski, Rafal

2001-01-01

This paper addresses three-axis attitude control for a Danish spacecraft, Roemer. The algorithm proposed is based on an approximation of the exact feedback linearisation for quaternionic attitude representation. The proposed attitude controller is tested in a simulation study. The environmental...

Gravity-gradient dynamics experiments performed in orbit utilizing the Radio Astronomy Explorer (RAE-1) spacecraft

Science.gov (United States)

Walden, H.

1973-01-01

Six dynamic experiments were performed in earth orbit utilizing the RAE spacecraft in order to test the accuracy of the mathematical model of RAE dynamics. The spacecraft consisted of four flexible antenna booms, mounted on a rigid cylindrical spacecraft hub at center, for measuring radio emissions from extraterrestrial sources. Attitude control of the gravity stabilized spacecraft was tested by using damper clamping, single lower leading boom operations, and double lower boom operations. Results and conclusions of the in-orbit dynamic experiments proved the accuracy of the analytic techniques used to model RAE dynamical behavior.

A Research on the Electrical Test Fault Diagnostic and Data Mining of a Manned Spacecraft

Directory of Open Access Journals (Sweden)

Yang Feng

2017-01-01

Full Text Available The paper introduces the modeling method and modeling tool for the fault diagnosis of manned spacecraft, the multi-signal flow graph model of a manned space equipment was established using this method; the framework of the fault detection and diagnosis system of manned spacecraft is proposed, the function of ground system and function of the spacecraft are clearly defined. The structure of the functional module is given separately; finally, the tool builds the fault detection and diagnosis system, the application of fault diagnosis method for manned spacecraft is used for reference.

Toward Accurate On-Ground Attitude Determination for the Gaia Spacecraft

Science.gov (United States)

Samaan, Malak A.

2010-03-01

The work presented in this paper concerns the accurate On-Ground Attitude (OGA) reconstruction for the astrometry spacecraft Gaia in the presence of disturbance and of control torques acting on the spacecraft. The reconstruction of the expected environmental torques which influence the spacecraft dynamics will be also investigated. The telemetry data from the spacecraft will include the on-board real-time attitude, which is of order of several arcsec. This raw attitude is the starting point for the further attitude reconstruction. The OGA will use the inputs from the field coordinates of known stars (attitude stars) and also the field coordinate differences of objects on the Sky Mapper (SM) and Astrometric Field (AF) payload instruments to improve this raw attitude. The on-board attitude determination uses a Kalman Filter (KF) to minimize the attitude errors and produce a more accurate attitude estimation than the pure star tracker measurement. Therefore the first approach for the OGA will be an adapted version of KF. Furthermore, we will design a batch least squares algorithm to investigate how to obtain a more accurate OGA estimation. Finally, a comparison between these different attitude determination techniques in terms of accuracy, robustness, speed and memory required will be evaluated in order to choose the best attitude algorithm for the OGA. The expected resulting accuracy for the OGA determination will be on the order of milli-arcsec.

Hard-real-time resource management for autonomous spacecraft

Science.gov (United States)

Gat, E.

2000-01-01

This paper describes tickets, a computational mechanism for hard-real-time autonomous resource management. Autonomous spacecraftcontrol can be considered abstractly as a computational process whose outputs are spacecraft commands.

Internal Mass Motion for Spacecraft Dynamics and Control

National Research Council Canada - National Science Library

Hall, Christopher D

2008-01-01

We present a detailed description of the application of a noncanonical Hamiltonian formulation to the modeling, analysis, and simulation of the dynamics of gyrostat spacecraft with internal mass motion...

Development of etched nuclear tracks

International Nuclear Information System (INIS)

Somogyi, G.

1980-01-01

The theoretical description of the evolution of etched tracks in solid state nuclear track detectors is considered for different initial conditions, for the cases of constant and varying track etch rates, isotropic and anisotropic bulk etching as well as for thick and thin detectors. It is summarized how one can calculate the main parameters of etch-pit geometry, the track length, the axes of a surface track opening, track profile and track contour. The application of the theory of etch-track evolution is demonstrated with selected practical problems. Attention is paid to certain questions related to the determination of unknown track parameters and calculation of surface track sizes. Finally, the theory is extended to the description of the perforation and etch-hole evolution process in thin detectors, which is of particular interest for track radiography and nuclear filter production. (orig.)

Development of etched nuclear tracks

International Nuclear Information System (INIS)

Somogyi, G.

1979-01-01

The theoretical description of the evolution of etched tracks in solid state nuclear track detectors is considered for different initial conditions, for the cases of constant and varying track etch rates, isotopic and unisotropic bulk etching as well as for thick and thin detectors. It is summarized how the main parameters of etch-pit geometry, the track length, the axes of a surface track opening, the track profile and the track contour can be calculated. The application of the theory of etch-track evolution is demonstrated with selected practical problems. Attention is paid to certain questions related to the determination of unknown track parameters and calculation of surface track sizes. Finally, the theory is extended to the description of the perforation and etch-hole evolution process in thin detectors, which is of particular interest for track radiography and nuclear filter production. (author)

Studies of Fission Fragment Rocket Engine Propelled Spacecraft

Science.gov (United States)

Werka, Robert O.; Clark, Rodney; Sheldon, Rob; Percy, Thomas K.

2014-01-01

The NASA Office of Chief Technologist has funded from FY11 through FY14 successive studies of the physics, design, and spacecraft integration of a Fission Fragment Rocket Engine (FFRE) that directly converts the momentum of fission fragments continuously into spacecraft momentum at a theoretical specific impulse above one million seconds. While others have promised future propulsion advances if only you have the patience, the FFRE requires no waiting, no advances in physics and no advances in manufacturing processes. Such an engine unequivocally can create a new era of space exploration that can change spacecraft operation. The NIAC (NASA Institute for Advanced Concepts) Program Phase 1 study of FY11 first investigated how the revolutionary FFRE technology could be integrated into an advanced spacecraft. The FFRE combines existent technologies of low density fissioning dust trapped electrostatically and high field strength superconducting magnets for beam management. By organizing the nuclear core material to permit sufficient mean free path for escape of the fission fragments and by collimating the beam, this study showed the FFRE could convert nuclear power to thrust directly and efficiently at a delivered specific impulse of 527,000 seconds. The FY13 study showed that, without increasing the reactor power, adding a neutral gas to the fission fragment beam significantly increased the FFRE thrust through in a manner analogous to a jet engine afterburner. This frictional interaction of gas and beam resulted in an engine that continuously produced 1000 pound force of thrust at a delivered impulse of 32,000 seconds, thereby reducing the currently studied DRM 5 round trip mission to Mars from 3 years to 260 days. By decreasing the gas addition, this same engine can be tailored for much lower thrust at much higher impulse to match missions to more distant destinations. These studies created host spacecraft concepts configured for manned round trip journeys. While the

Autonomous spacecraft rendezvous and docking

Science.gov (United States)

Tietz, J. C.; Almand, B. J.

A storyboard display is presented which summarizes work done recently in design and simulation of autonomous video rendezvous and docking systems for spacecraft. This display includes: photographs of the simulation hardware, plots of chase vehicle trajectories from simulations, pictures of the docking aid including image processing interpretations, and drawings of the control system strategy. Viewgraph-style sheets on the display bulletin board summarize the simulation objectives, benefits, special considerations, approach, and results.

Application of dynamic uncertain causality graph in spacecraft fault diagnosis: Logic cycle

Science.gov (United States)

Yao, Quanying; Zhang, Qin; Liu, Peng; Yang, Ping; Zhu, Ma; Wang, Xiaochen

2017-04-01

Intelligent diagnosis system are applied to fault diagnosis in spacecraft. Dynamic Uncertain Causality Graph (DUCG) is a new probability graphic model with many advantages. In the knowledge expression of spacecraft fault diagnosis, feedback among variables is frequently encountered, which may cause directed cyclic graphs (DCGs). Probabilistic graphical models (PGMs) such as bayesian network (BN) have been widely applied in uncertain causality representation and probabilistic reasoning, but BN does not allow DCGs. In this paper, DUGG is applied to fault diagnosis in spacecraft: introducing the inference algorithm for the DUCG to deal with feedback. Now, DUCG has been tested in 16 typical faults with 100% diagnosis accuracy.

Structural Dynamic Analyses And Test Predictions For Spacecraft Structures With Non-Linearities

Science.gov (United States)

Vergniaud, Jean-Baptiste; Soula, Laurent; Newerla, Alfred

2012-07-01

The overall objective of the mechanical development and verification process is to ensure that the spacecraft structure is able to sustain the mechanical environments encountered during launch. In general the spacecraft structures are a-priori assumed to behave linear, i.e. the responses to a static load or dynamic excitation, respectively, will increase or decrease proportionally to the amplitude of the load or excitation induced. However, past experiences have shown that various non-linearities might exist in spacecraft structures and the consequences of their dynamic effects can significantly affect the development and verification process. Current processes are mainly adapted to linear spacecraft structure behaviour. No clear rules exist for dealing with major structure non-linearities. They are handled outside the process by individual analysis and margin policy, and analyses after tests to justify the CLA coverage. Non-linearities can primarily affect the current spacecraft development and verification process on two aspects. Prediction of flights loads by launcher/satellite coupled loads analyses (CLA): only linear satellite models are delivered for performing CLA and no well-established rules exist how to properly linearize a model when non- linearities are present. The potential impact of the linearization on the results of the CLA has not yet been properly analyzed. There are thus difficulties to assess that CLA results will cover actual flight levels. Management of satellite verification tests: the CLA results generated with a linear satellite FEM are assumed flight representative. If the internal non- linearities are present in the tested satellite then there might be difficulties to determine which input level must be passed to cover satellite internal loads. The non-linear behaviour can also disturb the shaker control, putting the satellite at risk by potentially imposing too high levels. This paper presents the results of a test campaign performed in

Sampling strong tracking nonlinear unscented Kalman filter and its application in eye tracking

International Nuclear Information System (INIS)

Zu-Tao, Zhang; Jia-Shu, Zhang

2010-01-01

The unscented Kalman filter is a developed well-known method for nonlinear motion estimation and tracking. However, the standard unscented Kalman filter has the inherent drawbacks, such as numerical instability and much more time spent on calculation in practical applications. In this paper, we present a novel sampling strong tracking nonlinear unscented Kalman filter, aiming to overcome the difficulty in nonlinear eye tracking. In the above proposed filter, the simplified unscented transform sampling strategy with n + 2 sigma points leads to the computational efficiency, and suboptimal fading factor of strong tracking filtering is introduced to improve robustness and accuracy of eye tracking. Compared with the related unscented Kalman filter for eye tracking, the proposed filter has potential advantages in robustness, convergence speed, and tracking accuracy. The final experimental results show the validity of our method for eye tracking under realistic conditions. (classical areas of phenomenology)

Pose estimation and tracking of non-cooperative rocket bodies using Time-of-Flight cameras

Science.gov (United States)

Gómez Martínez, Harvey; Giorgi, Gabriele; Eissfeller, Bernd

2017-10-01

This paper presents a methodology for estimating the position and orientation of a rocket body in orbit - the target - undergoing a roto-translational motion, with respect to a chaser spacecraft, whose task is to match the target dynamics for a safe rendezvous. During the rendezvous maneuver the chaser employs a Time-of-Flight camera that acquires a point cloud of 3D coordinates mapping the sensed target surface. Once the system identifies the target, it initializes the chaser-to-target relative position and orientation. After initialization, a tracking procedure enables the system to sense the evolution of the target's pose between frames. The proposed algorithm is evaluated using simulated point clouds, generated with a CAD model of the Cosmos-3M upper stage and the PMD CamCube 3.0 camera specifications.

Aircraft versus spacecraft for remote monitoring of water quality in U.S. coastal zones

Science.gov (United States)

Darnell, W. L.

1977-01-01

To provide guidance for conducting future water monitoring missions over U.S. coasts, aircraft and spacecraft approaches were defined and quantitatively compared. Sensors, aircraft and spacecraft were selected from current or developmental types for the hardware concepts and monitoring was assumed to begin in 1981-1983. Comparative data are presented on capabilities and costs to monitor both recognized pollution sites and broad shelf areas. For these mission requirements, a large fleet of light aircraft provided better coverage and at lower costs generally than one spacecraft, assuming a single, multi-spectral sensor on each platform. This result could change, however, should additional useful sensors with low cost penalties be found for the spacecraft.

Proposed Modifications to Engineering Design Guidelines Related to Resistivity Measurements and Spacecraft Charging

Science.gov (United States)

Dennison, J. R.; Swaminathan, Prasanna; Jost, Randy; Brunson, Jerilyn; Green, Nelson; Frederickson, A. Robb

2005-01-01

A key parameter in modeling differential spacecraft charging is the resistivity of insulating materials. This determines how charge will accumulate and redistribute across the spacecraft, as well as the time scale for charge transport and dissipation. Existing spacecraft charging guidelines recommend use of tests and imported resistivity data from handbooks that are based principally upon ASTM methods that are more applicable to classical ground conditions and designed for problems associated with power loss through the dielectric, than for how long charge can be stored on an insulator. These data have been found to underestimate charging effects by one to four orders of magnitude for spacecraft charging applications. A review is presented of methods to measure the resistive of highly insulating materials, including the electrometer-resistance method, the electrometer-constant voltage method, the voltage rate-of-change method and the charge storage method. This is based on joint experimental studies conducted at NASA Jet Propulsion Laboratory and Utah State University to investigate the charge storage method and its relation to spacecraft charging. The different methods are found to be appropriate for different resistivity ranges and for different charging circumstances. A simple physics-based model of these methods allows separation of the polarization current and dark current components from long duration measurements of resistivity over day- to month-long time scales. Model parameters are directly related to the magnitude of charge transfer and storage and the rate of charge transport. The model largely explains the observed differences in resistivity found using the different methods and provides a framework for recommendations for the appropriate test method for spacecraft materials with different resistivities and applications. The proposed changes to the existing engineering guidelines are intended to provide design engineers more appropriate methods for

Naturally etched tracks in apatites and the correction of fission track dating

CERN Document Server

Tien, J L

1999-01-01

Naturally etched tracks have been found in apatites from the rapid cooled, high-level Kunon pluton in the Zhangzhou Igneous Complex, SE China. This is manifested by the fact that the apatite fission track (FT) age derived from conventional counting of spontaneous and induced tracks yields a result of 140.6+-6.5 Ma, which is much older than the ages determined using other methods on different minerals from the same rock. When tracks are observed after etching the polished inner sections of the apatite grains, the naturally etched tracks characterized by having hazy boundaries can be distinguished from the normal tracks with sharp boundaries. The age obtained by omitting these fading-resistant hazy tracks, 76.5+-4.0 Ma, indicates the time of the Kunon pluton cooling down to approx 100 deg. C. The corrected peak age (73.8 Ma) is consistent with the other apatite FT peak ages (79.2 to 70.2 Ma) of the nearly contemporaneous plutons in the same igneous complex.

A Sustainable Spacecraft Component Database Solution, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Numerous spacecraft component databases have been developed to support NASA, DoD, and contractor design centers and design tools. Despite the clear utility of...

High-Performance Contaminant Monitor for Spacecraft, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The Vision for Space Exploration demands increasing reliance on real-time trace gas monitors onboard spacecraft. Present grab samples and badges will be inadequate...

A Fault-tolerant RISC Microprocessor for Spacecraft Applications

Science.gov (United States)

Timoc, Constantin; Benz, Harry

1990-01-01

Viewgraphs on a fault-tolerant RISC microprocessor for spacecraft applications are presented. Topics covered include: reduced instruction set computer; fault tolerant registers; fault tolerant ALU; and double rail CMOS logic.

Evaluation of spacecraft technology programs (effects on communication satellite business ventures), volume 1

Science.gov (United States)

Greenburg, J. S.; Gaelick, C.; Kaplan, M.; Fishman, J.; Hopkins, C.

1985-01-01

Commercial organizations as well as government agencies invest in spacecraft (S/C) technology programs that are aimed at increasing the performance of communications satellites. The value of these programs must be measured in terms of their impacts on the financial performane of the business ventures that may ultimately utilize the communications satellites. An economic evaluation and planning capability was developed and used to assess the impact of NASA on-orbit propulsion and space power programs on typical fixed satellite service (FSS) and direct broadcast service (DBS) communications satellite business ventures. Typical FSS and DBS spin and three-axis stabilized spacecraft were configured in the absence of NASA technology programs. These spacecraft were reconfigured taking into account the anticipated results of NASA specified on-orbit propulsion and space power programs. In general, the NASA technology programs resulted in spacecraft with increased capability. The developed methodology for assessing the value of spacecraft technology programs in terms of their impact on the financial performance of communication satellite business ventures is described. Results of the assessment of NASA specified on-orbit propulsion and space power technology programs are presented for typical FSS and DBS business ventures.

Simulation of Tomographic Reconstruction of Magnetosphere Plasma Distribution By Multi-spacecraft Systems.

Science.gov (United States)

Kunitsyn, V.; Nesterov, I.; Andreeva, E.; Zelenyi, L.; Veselov, M.; Galperin, Y.; Buchner, J.

A satellite radiotomography method for electron density distributions was recently proposed for closely-space multi-spacecraft group of high-altitude satellites to study the physics of reconnection process. The original idea of the ROY project is to use a constellation of spacecrafts (one main and several sub-satellites) in order to carry out closely-spaced multipoint measurements and 2D tomographic reconstruction of elec- tron density in the space between the main satellite and the subsatellites. The distances between the satellites were chosen to vary from dozens to few hundreds of kilometers. The easiest data interpretation is achieved when the subsatellites are placed along the plasma streamline. Then, whenever a plasma density irregularity moves between the main satellite and the subsatellites it will be scanned in different directions and we can get 2D distribution of plasma using these projections. However in general sub- satellites are not placed exactly along the plasma streamline. The method of plasma velocity determination relative to multi-spacecraft systems is considered. Possibilities of 3D tomographic imaging using multi-spacecraft systems are analyzed. The model- ing has shown that efficient scheme for 3D tomographic imaging would be to place spacecrafts in different planes so that the angle between the planes would make not more then ten degrees. Work is supported by INTAS PROJECT 2000-465.

Laboratory investigations: Low Earth orbit environment chemistry with spacecraft surfaces

Science.gov (United States)

Cross, Jon B.

1990-01-01

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.

Sign tracking, but not goal tracking, is resistant to outcome devaluation

Directory of Open Access Journals (Sweden)

Sara E. Morrison

2015-12-01

Full Text Available During Pavlovian conditioning, a conditioned stimulus (CS may act as a predictor of a reward to be delivered in another location. Individuals vary widely in their propensity to engage with the CS (sign tracking or with the site of eventual reward (goal tracking. It is often assumed that sign tracking involves the association of the CS with the motivational value of the reward, resulting in the CS acquiring incentive value independent of the outcome. However, experimental evidence for this assumption is lacking. In order to test the hypothesis that sign tracking behavior does not rely on a neural representation of the outcome, we employed a reward devaluation procedure. We trained rats on a classic Pavlovian paradigm in which a lever CS was paired with a sucrose reward, then devalued the reward by pairing sucrose with illness in the absence of the CS. We found that sign tracking behavior was enhanced, rather than diminished, following reward devaluation; thus, sign tracking is clearly independent of a representation of the outcome. In contrast, goal tracking behavior was decreased by reward devaluation. Furthermore, when we divided rats into those with high propensity to engage with the lever (sign trackers and low propensity to engage with the lever (goal trackers, we found that nearly all of the effects of devaluation could be attributed to the goal trackers. These results show that sign tracking and goal tracking behavior may be the output of different associative structures in the brain, providing insight into the mechanisms by which reward-associated stimuli – such as drug cues – come to exert control over behavior in some individuals.

Sign Tracking, but Not Goal Tracking, is Resistant to Outcome Devaluation

Science.gov (United States)

Morrison, Sara E.; Bamkole, Michael A.; Nicola, Saleem M.

2015-01-01

During Pavlovian conditioning, a conditioned stimulus (CS) may act as a predictor of a reward to be delivered in another location. Individuals vary widely in their propensity to engage with the CS (sign tracking) or with the site of eventual reward (goal tracking). It is often assumed that sign tracking involves the association of the CS with the motivational value of the reward, resulting in the CS acquiring incentive value independent of the outcome. However, experimental evidence for this assumption is lacking. In order to test the hypothesis that sign tracking behavior does not rely on a neural representation of the outcome, we employed a reward devaluation procedure. We trained rats on a classic Pavlovian paradigm in which a lever CS was paired with a sucrose reward, then devalued the reward by pairing sucrose with illness in the absence of the CS. We found that sign tracking behavior was enhanced, rather than diminished, following reward devaluation; thus, sign tracking is clearly independent of a representation of the outcome. In contrast, goal tracking behavior was decreased by reward devaluation. Furthermore, when we divided rats into those with high propensity to engage with the lever (sign trackers) and low propensity to engage with the lever (goal trackers), we found that nearly all of the effects of devaluation could be attributed to the goal trackers. These results show that sign tracking and goal tracking behavior may be the output of different associative structures in the brain, providing insight into the mechanisms by which reward-associated stimuli—such as drug cues—come to exert control over behavior in some individuals. PMID:26733783

Delamination Assessment Tool for Spacecraft Composite Structures

Science.gov (United States)

Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

2012-07-01

Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

On-orbit assembly of a team of flexible spacecraft using potential field based method

Science.gov (United States)

Chen, Ti; Wen, Hao; Hu, Haiyan; Jin, Dongping

2017-04-01

In this paper, a novel control strategy is developed based on artificial potential field for the on-orbit autonomous assembly of four flexible spacecraft without inter-member collision. Each flexible spacecraft is simplified as a hub-beam model with truncated beam modes in the floating frame of reference and the communication graph among the four spacecraft is assumed to be a ring topology. The four spacecraft are driven to a pre-assembly configuration first and then to the assembly configuration. In order to design the artificial potential field for the first step, each spacecraft is outlined by an ellipse and a virtual leader of circle is introduced. The potential field mainly depends on the attitude error between the flexible spacecraft and its neighbor, the radial Euclidian distance between the ellipse and the circle and the classical Euclidian distance between the centers of the ellipse and the circle. It can be demonstrated that there are no local minima for the potential function and the global minimum is zero. If the function is equal to zero, the solution is not a certain state, but a set. All the states in the set are corresponding to the desired configurations. The Lyapunov analysis guarantees that the four spacecraft asymptotically converge to the target configuration. Moreover, the other potential field is also included to avoid the inter-member collision. In the control design of the second step, only small modification is made for the controller in the first step. Finally, the successful application of the proposed control law to the assembly mission is verified by two case studies.

Properties of Coronal Shocks at the Origin of SEP events Observed by Only One Single Spacecraft

Science.gov (United States)

Lario, D.; Kwon, R.

2017-12-01

The simultaneous observation of solar energetic particle (SEP) events by multiple spacecraft distributed in the interplanetary medium depends not only on the spatial separation among the different spacecraft, but also on the properties of the particle sources and the characteristics of the SEP transport in interplanetary space. Among the SEP events observed by STEREO-A, STEREO-B and/or near-Earth spacecraft during solar cycle 24, we select SEP events observed by a single spacecraft (specifically, the SEP events observed only by near-Earth spacecraft on 2012 April 5, 2011 September 4, and 2013 August 17). We analyze whether the properties of the coronal shock associated with the origin of the events (as seen in extreme-ultraviolet and white-light coronal images) differ from those associated with SEP events observed by two or three spacecraft. For the selected events we find that the associated CMEs are, in general, narrower than those associated with SEP events observed by two or three spacecraft. The confined extension of the parent coronal shock and the absence of magnetic connection between distant spacecraft and the regions of the expanding coronal shock able to efficiently accelerate SEPs seem to be the conditions leading to intense SEP events observed only over narrow regions of interplanetary space by spacecraft magnetically connected to regions close to the parent eruption site. Weak and gradual intensity increases observed in extended regions of space might involve transport processes and/or later connections established with interplanetary shocks. Systematic analyses of a larger number of events are required before drawing firm conclusions.

A novel strong tracking finite-difference extended Kalman filter for nonlinear eye tracking

Institute of Scientific and Technical Information of China (English)

ZHANG ZuTao; ZHANG JiaShu

2009-01-01

Non-Intrusive methods for eye tracking are Important for many applications of vision-based human computer interaction. However, due to the high nonlinearity of eye motion, how to ensure the robust-ness of external interference and accuracy of eye tracking poses the primary obstacle to the integration of eye movements into today's interfaces. In this paper, we present a strong tracking finite-difference extended Kalman filter algorithm, aiming to overcome the difficulty In modeling nonlinear eye tracking. In filtering calculation, strong tracking factor is introduced to modify a priori covariance matrix and im-prove the accuracy of the filter. The filter uses finite-difference method to calculate partial derivatives of nonlinear functions for eye tracking. The latest experimental results show the validity of our method for eye tracking under realistic conditions.

SMART-1: the first spacecraft of the future

Science.gov (United States)

2003-09-01

This is the first of a series of missions designed to test key technologies for future spacecraft —SMART stands for 'Small Missions for Advanced Research and Technology'. In the case of SMART-1, the two main new technologies to be tested are a new 'solar-electric propulsion' system and miniaturised spacecraft and instrumentation. Together, these technologies make up a spacecraft with revolutionary qualities: smaller, lighter, capable of carrying more scientific instruments, greater fuel efficiency. All of which also considerably reduces the cost of the mission. So, the idea behind SMART-1 is to pioneer a futuristic philosophy, the motto of which could be: 'more science for less money'. Even though it is the first of a kind, SMART-1 has been developed in less than four years, and at about a fifth of the cost of a major science mission for ESA: only 110 million euros. That includes the launch, the operations and a dozen scientific experiments. This was achieved partly by using new management methods — such as working with smaller teams both within ESA and in the industry — and partly because of some of the new features inherent in SMART-1, such as the miniaturisation and novel design. Giuseppe Racca, SMART-1 Project Manager, explains: "What has been our trick? First, a short development period in itself means less money. But also, with its small size — which was a requirement of the mission because we are testing miniaturised hardware — the spacecraft is able to 'share' a commercial Ariane flight with two other passengers. Besides, since we were not constrained by any existing design or heritage, we could be more innovative and elegant in our architecture. For example, the new SMART-1 electrical architecture has enabled us to simplify the system tests considerably." SMART-1 could almost be a toy spacecraft — it weighs only 367 kilograms and fits into a cube just one metre across (the solar panel wings extend about 14 metres) — although one able to

Range measurements and track kinetics in Dielectric Nuclear Track Detectors (DNTDs)

Energy Technology Data Exchange (ETDEWEB)

Aframian, A

1981-01-01

Observations of nuclear track development profiles and the kinetics of etched tracks in sensitive dielectric nuclear track detectors indicate three separate phases: the inception phase or the cone phase, the transition phase and the sphere phase. Continued etching of the sphere phase to through-tracks yields accurate range data for particles of different masses and energies and minimum critical angles of registration for each particle. The present results show an energy resolution of 40 keV (fwhm) for 5.48 MeV alpha-particles emitted from Am-241.

Microgravity Flammability Experiments for Spacecraft Fire Safety

DEFF Research Database (Denmark)

Legros, Guillaume; Minster, Olivier; Tóth, Balazs

2012-01-01

As fire behaviour in manned spacecraft still remains poorly understood, an international topical team has been created to design a validation experiment that has an unprecedented large scale for a microgravity flammability experiment. While the validation experiment is being designed for a re-sup...

Odor Control in Spacecraft Waste Management, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Spacecraft and lunar bases generate a variety of wastes containing water, including food wastes, feces, and brines. Disposal of these wastes, as well as recovery of...

Passive Wireless Sensors for Spacecraft Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — New classes of sensors are needed on spacecraft that can be interrogated remotely using RF signals and respond with the sensor's identity as well as the...

The use of twin-screen-based WIMPS in spacecraft control

Science.gov (United States)

Klim, R. D.

1990-10-01

The ergonomic problems of designing a sophisticated Windows Icons Mouse Pop-up (WIMP) based twin screen workstation are outlined. These same problems will be encountered by future spacecraft controllers. The design of a modern, advanced workstation for use on a distributed multicontrol center in a multisatellite control system is outlined. The system uses access control mechanisms to ensure that only authorized personnel can undertake certain operations on the workstation. Rules governing the use of windowing features, screen attributes, icons, keyboard and mouse in spacecraft control are discussed.

Space Weather Magnetometer Set with Automated AC Spacecraft Field Correction for GEO-KOMPSAT-2A

Science.gov (United States)

Auster, U.; Magnes, W.; Delva, M.; Valavanoglou, A.; Leitner, S.; Hillenmaier, O.; Strauch, C.; Brown, P.; Whiteside, B.; Bendyk, M.; Hilgers, A.; Kraft, S.; Luntama, J. P.; Seon, J.

2016-05-01

Monitoring the solar wind conditions, in particular its magnetic field (interplanetary magnetic field) ahead of the Earth is essential in performing accurate and reliable space weather forecasting. The magnetic condition of the spacecraft itself is a key parameter for the successful performance of the magnetometer onboard. In practice a condition with negligible magnetic field of the spacecraft cannot always be fulfilled and magnetic sources on the spacecraft interfere with the natural magnetic field measured by the space magnetometer. The presented "ready-to-use" Service Oriented Spacecraft Magnetometer (SOSMAG) is developed for use on any satellite implemented without magnetic cleanliness programme. It enables detection of the spacecraft field AC variations on a proper time scale suitable to distinguish the magnetic field variations relevant to space weather phenomena, such as sudden increase in the interplanetary field or southward turning. This is achieved through the use of dual fluxgate magnetometers on a short boom (1m) and two additional AMR sensors on the spacecraft body, which monitor potential AC disturbers. The measurements of the latter sensors enable an automated correction of the AC signal contributions from the spacecraft in the final magnetic vector. After successful development and test of the EQM prototype, a flight model (FM) is being built for the Korean satellite Geo-Kompsat 2A, with launch foreseen in 2018.

Critical Spacecraft-to-Earth Communications for Mars Exploration Rover (MER) entry, descent and landing

Science.gov (United States)

Hurd, William J.; Estabrook, Polly; Racho, Caroline S.; Satorius, Edgar H.

2002-01-01

For planetary lander missions, the most challenging phase of the spacecraft to ground communications is during the entry, descent, and landing (EDL). As each 2003 Mars Exploration Rover (MER) enters the Martian atmosphere, it slows dramatically. The extreme acceleration and jerk cause extreme Doppler dynamics on the X-band signal received on Earth. When the vehicle slows sufficiently, the parachute is deployed, causing almost a step in deceleration. After parachute deployment, the lander is lowered beneath the parachute on a bridle. The swinging motion of the lander imparts high Doppler dynamics on the signal and causes the received signal strength to vary widely, due to changing antenna pointing angles. All this time, the vehicle transmits important health and status information that is especially critical if the landing is not successful. Even using the largest Deep Space Network antennas, the weak signal and high dynamics render it impossible to conduct reliable phase coherent communications. Therefore, a specialized form of frequency-shift-keying will be used. This paper describes the EDL scenario, the signal conditions, the methods used to detect and frequency-track the carrier and to detect the data modulation, and the resulting performance estimates.

Adaptive extended-state observer-based fault tolerant attitude control for spacecraft with reaction wheels

Science.gov (United States)

Ran, Dechao; Chen, Xiaoqian; de Ruiter, Anton; Xiao, Bing

2018-04-01

This study presents an adaptive second-order sliding control scheme to solve the attitude fault tolerant control problem of spacecraft subject to system uncertainties, external disturbances and reaction wheel faults. A novel fast terminal sliding mode is preliminarily designed to guarantee that finite-time convergence of the attitude errors can be achieved globally. Based on this novel sliding mode, an adaptive second-order observer is then designed to reconstruct the system uncertainties and the actuator faults. One feature of the proposed observer is that the design of the observer does not necessitate any priori information of the upper bounds of the system uncertainties and the actuator faults. In view of the reconstructed information supplied by the designed observer, a second-order sliding mode controller is developed to accomplish attitude maneuvers with great robustness and precise tracking accuracy. Theoretical stability analysis proves that the designed fault tolerant control scheme can achieve finite-time stability of the closed-loop system, even in the presence of reaction wheel faults and system uncertainties. Numerical simulations are also presented to demonstrate the effectiveness and superiority of the proposed control scheme over existing methodologies.

Large scale tracking algorithms

Energy Technology Data Exchange (ETDEWEB)

Hansen, Ross L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Love, Joshua Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Melgaard, David Kennett [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Karelitz, David B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pitts, Todd Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zollweg, Joshua David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, Dylan Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nandy, Prabal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Whitlow, Gary L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bender, Daniel A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Byrne, Raymond Harry [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-01-01

Low signal-to-noise data processing algorithms for improved detection, tracking, discrimination and situational threat assessment are a key research challenge. As sensor technologies progress, the number of pixels will increase signi cantly. This will result in increased resolution, which could improve object discrimination, but unfortunately, will also result in a significant increase in the number of potential targets to track. Many tracking techniques, like multi-hypothesis trackers, suffer from a combinatorial explosion as the number of potential targets increase. As the resolution increases, the phenomenology applied towards detection algorithms also changes. For low resolution sensors, "blob" tracking is the norm. For higher resolution data, additional information may be employed in the detection and classfication steps. The most challenging scenarios are those where the targets cannot be fully resolved, yet must be tracked and distinguished for neighboring closely spaced objects. Tracking vehicles in an urban environment is an example of such a challenging scenario. This report evaluates several potential tracking algorithms for large-scale tracking in an urban environment.

Dynamics and control of robotic spacecrafts for the transportation of flexible elements

International Nuclear Information System (INIS)

Wen, Hao; Chen, Ti; Yu, Bensong; Jin, Dongping

2016-01-01

The technology of robotic spacecrafts has been identified as one of the most appealing solutions to the on-orbit construction of large space structures in future space missions. As a prerequisite of a successful on-orbit construction, it is needed to use small autonomous spacecrafts for the transportation of flexible elements. To this end, the paper presents an energy-based scheme to control a couple of robotic spacecrafts carrying a flexible slender structure to its desired position. The flexible structure is modelled as a long beam based on the formulation of absolute nodal coordinates to account for the geometrical nonlinearity due to large displacement. Meanwhile, the robotic spacecrafts are actuated on their rigid-body degrees of freedom and modelled as two rigid bodies attached to the flexible beam. The energy-based controller is designed using the technique of energy shaping and damping injection such that translational and rotational maneuvers can be achieved with the suppression of the flexible vibrations of the beam. Finally, numerical case studies are performed to demonstrate the proposed schemes. (paper)

DET/MPS - THE GSFC ENERGY BALANCE PROGRAM, DIRECT ENERGY TRANSFER/MULTIMISSION SPACECRAFT MODULAR POWER SYSTEM (UNIX VERSION)

Science.gov (United States)

Jagielski, J. M.

1994-01-01

The DET/MPS programs model and simulate the Direct Energy Transfer and Multimission Spacecraft Modular Power System in order to aid both in design and in analysis of orbital energy balance. Typically, the DET power system has the solar array directly to the spacecraft bus, and the central building block of MPS is the Standard Power Regulator Unit. DET/MPS allows a minute-by-minute simulation of the power system's performance as it responds to various orbital parameters, focusing its output on solar array output and battery characteristics. While this package is limited in terms of orbital mechanics, it is sufficient to calculate eclipse and solar array data for circular or non-circular orbits. DET/MPS can be adjusted to run one or sequential orbits up to about one week, simulated time. These programs have been used on a variety of Goddard Space Flight Center spacecraft projects. DET/MPS is written in FORTRAN 77 with some VAX-type extensions. Any FORTRAN 77 compiler that includes VAX extensions should be able to compile and run the program with little or no modifications. The compiler must at least support free-form (or tab-delineated) source format and 'do do-while end-do' control structures. DET/MPS is available for three platforms: GSC-13374, for DEC VAX series computers running VMS, is available in DEC VAX Backup format on a 9-track 1600 BPI tape (standard distribution) or TK50 tape cartridge; GSC-13443, for UNIX-based computers, is available on a .25 inch streaming magnetic tape cartridge in UNIX tar format; and GSC-13444, for Macintosh computers running AU/X with either the NKR FORTRAN or AbSoft MacFORTRAN II compilers, is available on a 3.5 inch 800K Macintosh format diskette. Source code and test data are supplied. The UNIX version of DET requires 90K of main memory for execution. DET/MPS was developed in 1990. A/UX and Macintosh are registered trademarks of Apple Computer, Inc. VMS, DEC VAX and TK50 are trademarks of Digital Equipment Corporation. UNIX is a

Application of square-root filtering for spacecraft attitude control

Science.gov (United States)

Sorensen, J. A.; Schmidt, S. F.; Goka, T.

1978-01-01

Suitable digital algorithms are developed and tested for providing on-board precision attitude estimation and pointing control for potential use in the Landsat-D spacecraft. These algorithms provide pointing accuracy of better than 0.01 deg. To obtain necessary precision with efficient software, a six state-variable square-root Kalman filter combines two star tracker measurements to update attitude estimates obtained from processing three gyro outputs. The validity of the estimation and control algorithms are established, and the sensitivity of their performance to various error sources and software parameters are investigated by detailed digital simulation. Spacecraft computer memory, cycle time, and accuracy requirements are estimated.

Quantization-Based Adaptive Actor-Critic Tracking Control With Tracking Error Constraints.

Science.gov (United States)

Fan, Quan-Yong; Yang, Guang-Hong; Ye, Dan

2018-04-01

In this paper, the problem of adaptive actor-critic (AC) tracking control is investigated for a class of continuous-time nonlinear systems with unknown nonlinearities and quantized inputs. Different from the existing results based on reinforcement learning, the tracking error constraints are considered and new critic functions are constructed to improve the performance further. To ensure that the tracking errors keep within the predefined time-varying boundaries, a tracking error transformation technique is used to constitute an augmented error system. Specific critic functions, rather than the long-term cost function, are introduced to supervise the tracking performance and tune the weights of the AC neural networks (NNs). A novel adaptive controller with a special structure is designed to reduce the effect of the NN reconstruction errors, input quantization, and disturbances. Based on the Lyapunov stability theory, the boundedness of the closed-loop signals and the desired tracking performance can be guaranteed. Finally, simulations on two connected inverted pendulums are given to illustrate the effectiveness of the proposed method.

Accelerated life testing of spacecraft subsystems

Science.gov (United States)

Wiksten, D.; Swanson, J.

1972-01-01

The rationale and requirements for conducting accelerated life tests on electronic subsystems of spacecraft are presented. A method for applying data on the reliability and temperature sensitivity of the parts contained in a sybsystem to the selection of accelerated life test parameters is described. Additional considerations affecting the formulation of test requirements are identified, and practical limitations of accelerated aging are described.

Rotational Motion Control of a Spacecraft

DEFF Research Database (Denmark)

Wisniewski, Rafal; Kulczycki, P.

2001-01-01

The paper adopts the energy shaping method to control of rotational motion. A global representation of the rigid body motion is given in the canonical form by a quaternion and its conjugate momenta. A general method for motion control on a cotangent bundle to the 3-sphere is suggested. The design...... algorithm is validated for three-axis spacecraft attitude control...

Rotational motion control of a spacecraft

DEFF Research Database (Denmark)

Wisniewski, Rafal; Kulczycki, P.

2003-01-01

The paper adopts the energy shaping method to control of rotational motion. A global representation of the rigid body motion is given in the canonical form by a quaternion and its conjugate momenta. A general method for motion control on a cotangent bundle to the 3-sphere is suggested. The design...... algorithm is validated for three-axis spacecraft attitude control. Udgivelsesdato: APR...

Small Spacecraft Technology Initiative Education Program

Science.gov (United States)

1995-01-01

A NASA engineer with the Commercial Remote Sensing Program (CRSP) at Stennis Space Center works with students from W.P. Daniels High School in New Albany, Miss., through NASA's Small Spacecraft Technology Initiative Program. CRSP is teaching students to use remote sensing to locate a potential site for a water reservoir to offset a predicted water shortage in the community's future.

Making tracks

Energy Technology Data Exchange (ETDEWEB)

Anon.

1986-10-15

In many modern tracking chambers, the sense wires, rather than being lined up uniformly, are grouped into clusters to facilitate the pattern recognition process. However, with higher energy machines providing collisions richer in secondary particles, event reconstruction becomes more complicated. A Caltech / Illinois / SLAC / Washington group developed an ingenious track finding and fitting approach for the Mark III detector used at the SPEAR electron-positron ring at SLAC (Stanford). This capitalizes on the detector's triggering, which uses programmable logic circuits operating in parallel, each 'knowing' the cell patterns for all tracks passing through a specific portion of the tracker (drift chamber)

Development of an advanced spacecraft tandem mass spectrometer

Science.gov (United States)

Drew, Russell C.

1992-03-01

The purpose of this research was to apply current advanced technology in electronics and materials to the development of a miniaturized Tandem Mass Spectrometer that would have the potential for future development into a package suitable for spacecraft use. The mass spectrometer to be used as a basis for the tandem instrument would be a magnetic sector instrument, of Nier-Johnson configuration, as used on the Viking Mars Lander mission. This instrument configuration would then be matched with a suitable second stage MS to provide the benefits of tandem MS operation for rapid identification of unknown organic compounds. This tandem instrument is configured with a newly designed GC system to aid in separation of complex mixtures prior to MS analysis. A number of important results were achieved in the course of this project. Among them were the development of a miniaturized GC subsystem, with a unique desorber-injector, fully temperature feedback controlled oven with powered cooling for rapid reset to ambient conditions, a unique combination inlet system to the MS that provides for both membrane sampling and direct capillary column sample transfer, a compact and ruggedized alignment configuration for the MS, an improved ion source design for increased sensitivity, and a simple, rugged tandem MS configuration that is particularly adaptable to spacecraft use because of its low power and low vacuum pumping requirements. The potential applications of this research include use in manned spacecraft like the space station as a real-time detection and warning device for the presence of potentially harmful trace contaminants of the spacecraft atmosphere, use as an analytical device for evaluating samples collected on the Moon or a planetary surface, or even use in connection with monitoring potentially hazardous conditions that may exist in terrestrial locations such as launch pads, environmental test chambers or other sensitive areas. Commercial development of the technology

Multisensor Distributed Track Fusion AlgorithmBased on Strong Tracking Filter and Feedback Integration1）

Institute of Scientific and Technical Information of China (English)

YANGGuo-Sheng; WENCheng-Lin; TANMin

2004-01-01

A new multisensor distributed track fusion algorithm is put forward based on combiningthe feedback integration with the strong tracking Kalman filter. Firstly, an effective tracking gateis constructed by taking the intersection of the tracking gates formed before and after feedback.Secondly, on the basis of the constructed effective tracking gate, probabilistic data association andstrong tracking Kalman filter are combined to form the new multisensor distributed track fusionalgorithm. At last, simulation is performed on the original algorithm and the algorithm presented.

Track finding and track reconstruction in the internal forward drift chamber of SAPHIR

International Nuclear Information System (INIS)

Umlauf, G.

1993-03-01

A track finding algorithm has been developed for the inner forward drift chamber of the SAPHIR detector (at ELSA in Bonn) using the Principal Components Analysis as a tool for interpolating track coordinates. The drift chamber consists of twelve planar layers with six different inclinations and is being operated in an inhomogenous magnetic field. The task of track finding is basicly split into a primary stage that defines track candidates without the use of drift-time information and a second stage that serves to verify the track candidate and to resolve the intrinsic left-right ambiguities of the drift chamber signals. Tracks with at most three missing signals can be found. (orig.) [de

Timber tracking

DEFF Research Database (Denmark)

Düdder, Boris; Ross, Omry

2017-01-01

Managing and verifying forest products in a value chain is often reliant on easily manipulated document or digital tracking methods - Chain of Custody Systems. We aim to create a new means of tracking timber by developing a tamper proof digital system based on Blockchain technology. Blockchain...

Digital image transformation and rectification of spacecraft and radar images

Science.gov (United States)

Wu, S. S. C.

1985-01-01

The application of digital processing techniques to spacecraft television pictures and radar images is discussed. The use of digital rectification to produce contour maps from spacecraft pictures is described; images with azimuth and elevation angles are converted into point-perspective frame pictures. The digital correction of the slant angle of radar images to ground scale is examined. The development of orthophoto and stereoscopic shaded relief maps from digital terrain and digital image data is analyzed. Digital image transformations and rectifications are utilized on Viking Orbiter and Lander pictures of Mars.

Effects of Space Weather on Geosynchronous Electromagnetic Spacecraft Perturbations Using Statistical Fluxes

Science.gov (United States)

Hughes, J.; Schaub, H.

2017-12-01

Spacecraft can charge to very negative voltages at GEO due to interactions with the space plasma. This can cause arcing which can damage spacecraft electronics or solar panels. Recently, it has been suggested that spacecraft charging may lead to orbital perturbations which change the orbits of lightweight uncontrolled debris orbits significantly. The motions of High Area to Mass Ratio objects are not well explained with just perturbations from Solar Radiation Pressure (SRP) and earth, moon, and sun gravity. A charged spacecraft will experience a Lorentz force as the spacecraft moves relative to Earth's magnetic field, as well as a Lorentz torque and eddy current torques if the object is rotating. Prior work assuming a constant "worst case" voltage has shown that Lorentz and eddy torques can cause quite large orbital changes by rotating the object to experience more or less SRP. For some objects, including or neglecting these electromagnetic torques can lead to differences of thousands of kilometers after only two orbits. This paper will further investigate the effects of electromagnetic perturbations by using a charging model that uses measured flux distributions to better simulate natural charging. This differs from prior work which used a constant voltage or Maxwellian distributions. This is done to a calm space weather case of Kp = 2 and a stormy case where Kp = 8. Preliminary analysis suggests that electrostatics will still cause large orbital changes even with the more realistic charging model.

A spacecraft's own ambient environment: The role of simulation-based research

Energy Technology Data Exchange (ETDEWEB)

Ketsdever, Andrew D. [University of Colorado Colorado Springs, Department of Mechanical and Aerospace Engineering, Colorado Springs, CO (United States); Gimelshein, Sergey [University of Southern California, Department of Astronautical Engineering, Los Angeles, CA (United States)

2014-12-09

Spacecraft contamination has long been a subject of study in the rarefied gas dynamics community. Professor Mikhail Ivanov coined the term a spacecraft's 'own ambient environment' to describe the effects of natural and satellite driven processes on the conditions encountered by a spacecraft in orbit. Outgassing, thruster firings, and gas and liquid dumps all contribute to the spacecraft's contamination environment. Rarefied gas dynamic modeling techniques, such as Direct Simulation Monte Carlo, are well suited to investigate these spacebased environments. However, many advances were necessary to fully characterize the extent of this problem. A better understanding of modeling flows over large pressure ranges, for example hybrid continuum and rarefied numerical schemes, were required. Two-phase flow modeling under rarefied conditions was necessary. And the ability to model plasma flows for a new era of propulsion systems was also required. Through the work of Professor Ivanov and his team, we now have a better understanding of processes that create a spacecraft's own ambient environment and are able to better characterize these environments. Advances in numerical simulation have also spurred on the development of experimental facilities to study these effects. The relationship between numerical results and experimental advances will be explored in this manuscript.

Spacecraft Dynamic Characterization by Strain Energies Method

Science.gov (United States)

Bretagne, J.-M.; Fragnito, M.; Massier, S.

2002-01-01

In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven

Dependence of yield of nuclear track-biosensors on track radius and analyte concentration

Science.gov (United States)

García-Arellano, H.; Muñoz H., G.; Fink, D.; Vacik, J.; Hnatowicz, V.; Alfonta, L.; Kiv, A.

2018-04-01

In swift heavy ion track-based polymeric biosensor foils with incorporated enzymes one exploits the correlation between the analyte concentration and the sensor current, via the enrichment of charged enzymatic reaction products in the track's confinement. Here we study the influence of the etched track radius on the biosensor's efficiency. These sensors are analyte-specific only if both the track radii and the analyte concentration exceed certain threshold values of ∼15 nm and ∼10-6 M (for glucose sensing), respectively. Below these limits the sensor signal stems un-specifically from any charge carrier. In its proper working regime, the inner track walls are smoothly covered by enzymes and the efficiency is practically radius independent. Theory shows that the measured current should be slightly sub-proportional to the analyte concentration; the measurements roughly reconfirm this. Narrower tracks (∼5-15 nm radius) with reduced enzyme coverage lead to decreasing efficiency. Tiny signals visible when the tracks are etched to effective radii between 0 and ∼5 nm are tentatively ascribed to enzymes bonded to surface-near nano-cracks in the polymer foil, resulting from its degradation due to aging, rather than to the tracks. Precondition for this study was the accurate determination of the etched track radii, which is possible only by a nanofluidic approach. This holds to some extent even for enzyme-covered tracks, though in this case most of the wall charges are compensated by enzyme bonding.

Tracks: A National Environmental Public Health Tracking Network Overview

Centers for Disease Control (CDC) Podcasts

In this podcast, Dr. Mike McGeehin, Director of CDC's Division of Environmental Hazards and Health Effects, provides an overview of the National Environmental Public Health Tracking Network. It highlights the Tracking Network's goal, how it will improve public health, its audience, and much more.

Urbanism on Track : Application of tracking technologies in urbanism

NARCIS (Netherlands)

Van der Hoeven, F.D.; Van Schaick, J.; Van der Spek, S.C.; Smit, M.G.J.

2008-01-01

Tracking technologies such as GPS, mobile phone tracking, video and RFID monitoring are rapidly becoming part of daily life. Technological progress offers huge possibilities for studying human activity patterns in time and space in new ways. Delft University of Technology (TU Delft) held an

A historical overview of the electrical power systems in the US manned and some US unmanned spacecraft

Science.gov (United States)

Maisel, J. E.

1984-01-01

A historical overview of electrical power systems used in the U.S. manned spacecraft and some of the U.S. unmanned spacecraft is presented in this investigation. A time frame of approximately 25 years, the period for 1959 to 1984, is covered in this report. Results indicate that the nominal bus voltage was 28 volts dc in most spacecraft and all other voltage levels were derived from this voltage through such techniques as voltage inversion or rectification, or a combination. Most spacecraft used solar arrays for the main source of power except for those spacecraft that had a relatively short flight duration, or deep spaceprobes that were designed for very long flight duration. Fuel cells were used on Gemini, Apollo, and Space Shuttle (short duration flights) while radioisotope thermoelectric generators were employed on the Pioneer, Jupiter/Saturn, Viking Lander, and Voyager spacecraft (long duration flights). The main dc bus voltage was unregulated on the manned spacecraft with voltage regulation provided at the user loads. A combination of regulated, semiregulated, and unregulated buses were used on the unmanned spacecraft depending on the type of load. For example, scientific instruments were usually connected to regulated buses while fans, relays, etc. were energized from an unregulated bus. Different forms of voltage regulation, such as shunt, buck/boot, and pulse-width modulated regulators, were used. This report includes a comprehensive bibliography on spacecraft electrical power systems for the space programs investigated.

Small Rocket/Spacecraft Technology (SMART) Platform

Science.gov (United States)

Esper, Jaime; Flatley, Thomas P.; Bull, James B.; Buckley, Steven J.

2011-01-01

The NASA Goddard Space Flight Center (GSFC) and the Department of Defense Operationally Responsive Space (ORS) Office are exercising a multi-year collaborative agreement focused on a redefinition of the way space missions are designed and implemented. A much faster, leaner and effective approach to space flight requires the concerted effort of a multi-agency team tasked with developing the building blocks, both programmatically and technologically, to ultimately achieve flights within 7-days from mission call-up. For NASA, rapid mission implementations represent an opportunity to find creative ways for reducing mission life-cycle times with the resulting savings in cost. This in tum enables a class of missions catering to a broader audience of science participants, from universities to private and national laboratory researchers. To that end, the SMART (Small Rocket/Spacecraft Technology) micro-spacecraft prototype demonstrates an advanced avionics system with integrated GPS capability, high-speed plug-and-playable interfaces, legacy interfaces, inertial navigation, a modular reconfigurable structure, tunable thermal technology, and a number of instruments for environmental and optical sensing. Although SMART was first launched inside a sounding rocket, it is designed as a free-flyer.

Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the LADEE Spacecraft

Science.gov (United States)

Genova, A. L.

2014-01-01

This paper presents results from a contingency trajectory analysis performed for the Lunar Atmosphere & Dust Environment Explorer (LADEE) mission in the event of a missed lunar-orbit insertion (LOI) maneuver by the LADEE spacecraft. The effects of varying solar perturbations in the vicinity of the weak stability boundary (WSB) in the Sun-Earth system on the trajectory design are analyzed and discussed. It is shown that geocentric recovery trajectory options existed for the LADEE spacecraft, depending on the spacecraft's recovery time to perform an Earth escape-prevention maneuver after the hypothetical LOI maneuver failure and subsequent path traveled through the Sun-Earth WSB. If Earth-escape occurred, a heliocentric recovery option existed, but with reduced science capacapability for the spacecraft in an eccentric, not circular near-equatorial retrograde lunar orbit.

An insight on advantage of hybrid sun–wind-tracking over sun-tracking PV system

International Nuclear Information System (INIS)

Rahimi, Masoud; Banybayat, Meisam; Tagheie, Yaghoub; Valeh-e-Sheyda, Peyvand

2015-01-01

Graphical abstract: Real photograph of hybrid sun–wind-tracking system. - Highlights: • Novel hybrid sun–wind-tracking system proposed to enhance PV cell performance. • The wind tracker can cool down the PV cell as sun-tracking system work. • The hybrid tracker achieved 7.4% increase in energy gain over the sun tracker. • The overall daily output energy gain was increased by 49.83% by using this system. - Abstract: This paper introduces the design and application of a novel hybrid sun–wind-tracking system. This hybrid system employs cooling effect of wind, besides the advantages of tracking sun for enhancing power output from examined hybrid photovoltaic cell. The principal experiment focuses on comparison between dual-axes sun-tracking and hybrid sun–wind-tracking photovoltaic (PV) panels. The deductions based on the research tests confirm that the overall daily output energy gain was increased by 49.83% compared with that of a fixed system. Moreover, an overall increase of about 7.4% in the output power was found for the hybrid sun–wind-tracking over the two-axis sun tracking system.

Spacecraft fabrication and test MODIL. Final report

Energy Technology Data Exchange (ETDEWEB)

Saito, T.T.

1994-05-01

This report covers the period from October 1992 through the close of the project. FY 92 closed out with the successful briefing to industry and with many potential and important initiatives in the spacecraft arena. Due to the funding uncertainties, we were directed to proceed as if our funding would be approximately the same as FY 92 ($2M), but not to make any major new commitments. However, the MODIL`s FY 93 funding was reduced to $810K and we were directed to concentrate on the cryocooler area. The cryocooler effort completed its demonstration project. The final meetings with the cryocooler fabricators were very encouraging as we witnessed the enthusiastic reception of technology to help them reduce fabrication uncertainties. Support of the USAF Phillips Laboratory cryocooler program was continued including kick-off meetings for the Prototype Spacecraft Cryocooler (PSC). Under Phillips Laboratory support, Gill Cruz visited British Aerospace and Lucas Aerospace in the United Kingdom to assess their manufacturing capabilities. In the Automated Spacecraft & Assembly Project (ASAP), contracts were pursued for the analysis by four Brilliant Eyes prime contractors to provide a proprietary snap shot of their current status of Integrated Product Development. In the materials and structure thrust the final analysis was completed of the samples made under the contract (``Partial Automation of Matched Metal Net Shape Molding of Continuous Fiber Composites``) to SPARTA. The Precision Technologies thrust funded the Jet Propulsion Laboratory to prepare a plan to develop a Computer Aided Alignment capability to significantly reduce the time for alignment and even possibly provide real time and remote alignment capability of systems in flight.

Link Analysis of High Throughput Spacecraft Communication Systems for Future Science Missions

Science.gov (United States)

Simons, Rainee N.

2015-01-01

NASA's plan to launch several spacecrafts into low Earth Orbit (LEO) to support science missions in the next ten years and beyond requires down link throughput on the order of several terabits per day. The ability to handle such a large volume of data far exceeds the capabilities of current systems. This paper proposes two solutions, first, a high data rate link between the LEO spacecraft and ground via relay satellites in geostationary orbit (GEO). Second, a high data rate direct to ground link from LEO. Next, the paper presents results from computer simulations carried out for both types of links taking into consideration spacecraft transmitter frequency, EIRP, and waveform; elevation angle dependent path loss through Earths atmosphere, and ground station receiver GT.

Modeling and Analysis of Realistic Fire Scenarios in Spacecraft

Science.gov (United States)

Brooker, J. E.; Dietrich, D. L.; Gokoglu, S. A.; Urban, D. L.; Ruff, G. A.

2015-01-01

An accidental fire inside a spacecraft is an unlikely, but very real emergency situation that can easily have dire consequences. While much has been learned over the past 25+ years of dedicated research on flame behavior in microgravity, a quantitative understanding of the initiation, spread, detection and extinguishment of a realistic fire aboard a spacecraft is lacking. Virtually all combustion experiments in microgravity have been small-scale, by necessity (hardware limitations in ground-based facilities and safety concerns in space-based facilities). Large-scale, realistic fire experiments are unlikely for the foreseeable future (unlike in terrestrial situations). Therefore, NASA will have to rely on scale modeling, extrapolation of small-scale experiments and detailed numerical modeling to provide the data necessary for vehicle and safety system design. This paper presents the results of parallel efforts to better model the initiation, spread, detection and extinguishment of fires aboard spacecraft. The first is a detailed numerical model using the freely available Fire Dynamics Simulator (FDS). FDS is a CFD code that numerically solves a large eddy simulation form of the Navier-Stokes equations. FDS provides a detailed treatment of the smoke and energy transport from a fire. The simulations provide a wealth of information, but are computationally intensive and not suitable for parametric studies where the detailed treatment of the mass and energy transport are unnecessary. The second path extends a model previously documented at ICES meetings that attempted to predict maximum survivable fires aboard space-craft. This one-dimensional model implies the heat and mass transfer as well as toxic species production from a fire. These simplifications result in a code that is faster and more suitable for parametric studies (having already been used to help in the hatch design of the Multi-Purpose Crew Vehicle, MPCV).

Non-etching nuclear track visualization in polymers: fluorescent and dyed tracks

International Nuclear Information System (INIS)

Somogyi, G.; Toth-Szilagyi, M.; Monnin, M.; Gourcy, J.

1979-01-01

A report is presented on progress in two methods of non-etching nuclear track visualization. The basis for one method is to graft polymer chains in the vicinity of the ion path in a polymer, and then to dye it, making the track visible. The second method is similar, but in this case saturated organic molecules can be used, which prevents subsequent polymerization. The detector is soaked with a solution of a sensitization molecule that can react with a convenient dye and fix it. The sensitization molecules may diffuse into the detector either through the bulk of it or/ and along the region damaged by a charged particle. Depending on the detailed procedure used, the tracks may be seen as 'dyed tracks' with visible-light illumination or as 'fluorescent tracks' with u.v. illumination. Experimental procedures and results are given and discussed. (U.K.)

EnTracked: Energy-Efficient Robust Position Tracking for Mobile Devices

DEFF Research Database (Denmark)

Kjærgaard, Mikkel Baun; Jensen, Jakob Langdal; Godsk, Torben

2009-01-01

conditions and mobility, schedules position updates to both minimize energy consumption and optimize robustness. The realized system tracks pedestrian targets equipped with GPS-enabled devices. The system is configurable to realize different trade-offs between energy consumption and robustness. We provide...... of the mobile device. Furthermore, tracking has to robustly deliver position updates when faced with changing conditions such as delays due to positioning and communication, and changing positioning accuracy. This work proposes EnTracked --- a system that, based on the estimation and prediction of system...... extensive experimental results by profiling how devices consume power, by emulation on collected data and by validation in several real-world deployments. Results from this profiling show how a device consumes power while tracking its position. Results from the emulation indicate that the system can...

The Physics and Technology of Solar Sail Spacecraft.

Science.gov (United States)

Dwivedi, B. N.; McInnes, C. R.

1991-01-01

Various aspects of the solar sail spacecraft such as solar sailing, solar sail design, navigation with solar sails, solar sail mission applications and future prospects for solar sailing are described. Several possible student projects are suggested. (KR)

Combined spacecraft orbit and attitude control through extended Kalman filtering of magnetometer, gyro, and GPS measurements

Directory of Open Access Journals (Sweden)

Tamer Mekky Ahmed Habib

2014-06-01

Full Text Available The main goal of this research is to establish spacecraft orbit and attitude control algorithms based on extended Kalman filter which provides estimates of spacecraft orbital and attitude states. The control and estimation algorithms must be capable of dealing with the spacecraft conditions during the detumbling and attitude acquisition modes of operation. These conditions are characterized by nonlinearities represented by large initial attitude angles, large initial angular velocities, large initial attitude estimation error, and large initial position estimation error. All of the developed estimation and control algorithms are suitable for application to the next Egyptian scientific satellite, EGYPTSAT-2. The parameters of the case-study spacecraft are similar but not identical to the former Egyptian satellite EGYPTSAT-1. This is done because the parameters of EGYPTSAT-2 satellite have not been consolidated yet. The sensors utilized are gyro, magnetometer, and GPS. Gyro and magnetometer are utilized to provide measurements for the estimates of spacecraft attitude state vector where as magnetometer and GPS are utilized to provide measurements for the estimates of spacecraft orbital state vector.

Solid state nuclear track detectors

International Nuclear Information System (INIS)

Medeiros, J.A.; Carvalho, M.L.C.P. de

1992-12-01

Solid state nuclear track detectors (SSNTD) are dielectric materials, crystalline or vitreous, which registers tracks of charged nuclear particles, like alpha particles or fission fragments. Chemical etching of the detectors origin tracks that are visible at the optical microscope: track etching rate is higher along the latent track, where damage due to the charged particle increase the chemical potential, and etching rate giving rise to holes, the etched tracks. Fundamental principles are presented as well as some ideas of main applications. (author)

Model predictive control for spacecraft rendezvous in elliptical orbit

Science.gov (United States)

Li, Peng; Zhu, Zheng H.

2018-05-01

This paper studies the control of spacecraft rendezvous with attitude stable or spinning targets in an elliptical orbit. The linearized Tschauner-Hempel equation is used to describe the motion of spacecraft and the problem is formulated by model predictive control. The control objective is to maximize control accuracy and smoothness simultaneously to avoid unexpected change or overshoot of trajectory for safe rendezvous. It is achieved by minimizing the weighted summations of control errors and increments. The effects of two sets of horizons (control and predictive horizons) in the model predictive control are examined in terms of fuel consumption, rendezvous time and computational effort. The numerical results show the proposed control strategy is effective.

Differences between the CME fronts tracked by an expert, an automated algorithm, and the Solar Stormwatch project

Science.gov (United States)

Barnard, L.; Scott, C. J.; Owens, M.; Lockwood, M.; Crothers, S. R.; Davies, J. A.; Harrison, R. A.

2015-10-01

Observations from the Heliospheric Imager (HI) instruments aboard the twin STEREO spacecraft have enabled the compilation of several catalogues of coronal mass ejections (CMEs), each characterizing the propagation of CMEs through the inner heliosphere. Three such catalogues are the Rutherford Appleton Laboratory (RAL)-HI event list, the Solar Stormwatch CME catalogue, and, presented here, the J-tracker catalogue. Each catalogue uses a different method to characterize the location of CME fronts in the HI images: manual identification by an expert, the statistical reduction of the manual identifications of many citizen scientists, and an automated algorithm. We provide a quantitative comparison of the differences between these catalogues and techniques, using 51 CMEs common to each catalogue. The time-elongation profiles of these CME fronts are compared, as are the estimates of the CME kinematics derived from application of three widely used single-spacecraft-fitting techniques. The J-tracker and RAL-HI profiles are most similar, while the Solar Stormwatch profiles display a small systematic offset. Evidence is presented that these differences arise because the RAL-HI and J-tracker profiles follow the sunward edge of CME density enhancements, while Solar Stormwatch profiles track closer to the antisunward (leading) edge. We demonstrate that the method used to produce the time-elongation profile typically introduces more variability into the kinematic estimates than differences between the various single-spacecraft-fitting techniques. This has implications for the repeatability and robustness of these types of analyses, arguably especially so in the context of space weather forecasting, where it could make the results strongly dependent on the methods used by the forecaster.

Measurement of fission track of uranium particle by solid state nuclear track detector

International Nuclear Information System (INIS)

Son, S. C.; Pyo, H. W.; Ji, K. Y.; Kim, W. H.

2002-01-01

In this study, we discussed results of the measurement of fission tracks for the uranium containing particles by solid state nuclear track detector. Uranium containing silica and uranium oxide particles were prepared by uranium sorption onto silica powder in weak acidic medium and laser ablation on uranium pellet, respectively. Fission tracks for the uranium containing silica and uranium oxide particles were detected on Lexan plastic detector. It was found that the fission track size and shapes depend on the particle size uranium content in particles. Correlation of uranium particle diameter with fission track radius was also discussed

Spacecraft Angular Rates Estimation with Gyrowheel Based on Extended High Gain Observer

Directory of Open Access Journals (Sweden)

Xiaokun Liu

2016-04-01

Full Text Available A gyrowheel (GW is a kind of electronic electric-mechanical servo system, which can be applied to a spacecraft attitude control system (ACS as both an actuator and a sensor simultaneously. In order to solve the problem of two-dimensional spacecraft angular rate sensing as a GW outputting three-dimensional control torque, this paper proposed a method of an extended high gain observer (EHGO with the derived GW mathematical model to implement the spacecraft angular rate estimation when the GW rotor is working at large angles. For this purpose, the GW dynamic equation is firstly derived with the second kind Lagrange method, and the relationship between the measurable and unmeasurable variables is built. Then, the EHGO is designed to estimate and calculate spacecraft angular rates with the GW, and the stability of the designed EHGO is proven by the Lyapunov function. Moreover, considering the engineering application, the effect of measurement noise in the tilt angle sensors on the estimation accuracy of the EHGO is analyzed. Finally, the numerical simulation is performed to illustrate the validity of the method proposed in this paper.

Thermal shock induced dynamics of a spacecraft with a flexible deploying boom

Science.gov (United States)

Shen, Zhenxing; Li, Huijian; Liu, Xiaoning; Hu, Gengkai

2017-12-01

The dynamics in the process of deployment of a flexible extendible boom as a deployable structure on the spacecraft is studied. For determining the thermally induced vibrations of the boom subjected to an incident solar heat flux, an axially moving thermal-dynamic beam element based on the absolute nodal coordinate formulation which is able to precisely describe the large displacement, rotation and deformation of flexible body is presented. For the elastic forces formulation of variable-length beam element, the enhanced continuum mechanics approach is adopted, which can eliminate the Poisson locking effect, and take into account the tension-bending-torsion coupling deformations. The main body of the spacecraft, modeled as a rigid body, is described using the natural coordinates method. In the derived nonlinear thermal-dynamic equations of rigid-flexible multibody system, the mass matrix is time-variant, and a pseudo damping matrix which is without actual energy dissipation, and a heat conduction matrix which is relative to the moving speed and the number of beam element are arisen. Numerical results give the dynamic and thermal responses of the nonrotating and spinning spacecraft, respectively, and show that thermal shock has a significant influence on the dynamics of spacecraft.

Lifetime of a spacecraft around a synchronous system of asteroids using a dipole model

Science.gov (United States)

dos Santos, Leonardo Barbosa Torres; de Almeida Prado, Antonio F. Bertachini; Sanchez, Diogo Merguizo

2017-11-01

Space missions allow us to expand our knowledge about the origin of the solar system. It is believed that asteroids and comets preserve the physical characteristics from the time that the solar system was created. For this reason, there was an increase of missions to asteroids in the past few years. To send spacecraft to asteroids or comets is challenging, since these objects have their own characteristics in several aspects, such as size, shape, physical properties, etc., which are often only discovered after the approach and even after the landing of the spacecraft. These missions must be developed with sufficient flexibility to adjust to these parameters, which are better determined only when the spacecraft reaches the system. Therefore, conducting a dynamic investigation of a spacecraft around a multiple asteroid system offers an extremely rich environment. Extracting accurate information through analytical approaches is quite challenging and requires a significant number of restrictive assumptions. For this reason, a numerical approach to the dynamics of a spacecraft in the vicinity of a binary asteroid system is offered in this paper. In the present work, the equations of the Restricted Synchronous Four-Body Problem (RSFBP) are used to model a binary asteroid system. The main objective of this work is to construct grids of initial conditions, which relates semi-major axis and eccentricity, in order to quantify the lifetime of a spacecraft when released close to the less massive body of the binary system (modeled as a rotating mass dipole). We performed an analysis of the lifetime of the spacecraft considering several mass ratios of a binary system of asteroids and investigating the behavior of a spacecraft in the vicinity of this system. We analyze direct and retrograde orbits. This study investigated orbits that survive for at least 500 orbital periods of the system (which is approximately one year), then not colliding or escaping from the system during this