WorldWideScience

Sample records for candidate spacecraft electronics

  1. Compendium of Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA

    Science.gov (United States)

    Cochran, Donna J.; Boutte, Alvin J.; Chen, Dakai; Pellish, Jonathan A.; Ladbury, Raymond L.; Casey, Megan C.; Campola, Michael J.; Wilcox, Edward P.; Obryan, Martha V.; LaBel, Kenneth A.; Lauenstein, Jean-Marie; Batchlor, David A.; Oldham, Timothy R.

    2012-01-01

    Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear, and hybrid devices.

  2. Compendium of Single Event Effects, Total Ionizing Dose, and Displacement Damage for Candidate Spacecraft Electronics for NASA

    Science.gov (United States)

    LaBel, Kenneth A.; OBryan, Martha V.; Chen, Dakai; Campola, Michael J.; Casey, Megan C.; Pellish, Jonathan A.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Ladbury, Raymond L.; Berg, Melanie D.; Gigliuto, Robert A.; Boutte, Alvin J.; Cochran, Donna J.; Buchner, Stephen P.; Violette, Daniel P.

    2014-01-01

    We present results and analysis investigating the effects of radiation on a variety of candidate spacecraft electronics to proton and heavy ion induced single event effects (SEE), proton-induced displacement damage (DD), and total ionizing dose (TID). Introduction: This paper is a summary of test results.NASA spacecraft are subjected to a harsh space environment that includes exposure to various types of ionizing radiation. The performance of electronic devices in a space radiation environment is often limited by its susceptibility to single event effects (SEE), total ionizing dose (TID), and displacement damage (DD). Ground-based testing is used to evaluate candidate spacecraft electronics to determine risk to spaceflight applications. Interpreting the results of radiation testing of complex devices is quite difficult. Given the rapidly changing nature of technology, radiation test data are most often application-specific and adequate understanding of the test conditions is critical. Studies discussed herein were undertaken to establish the application-specific sensitivities of candidate spacecraft and emerging electronic devices to single-event upset (SEU), single-event latchup (SEL), single-event gate rupture (SEGR), single-event burnout (SEB), single-event transient (SET), TID, enhanced low dose rate sensitivity (ELDRS), and DD effects.

  3. 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.

  4. Cluster PEACE observations of electrons of spacecraft origin

    Directory of Open Access Journals (Sweden)

    S. Szita

    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

  5. Charge Dissipating Transparent Conformal Coatings for Spacecraft Electronics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The space environment poses significant challenges to spacecraft electronics in the form of electrostatic discharge (ESD) as a result of exposure to highly charged...

  6. Maintainability design criteria for packaging of spacecraft replaceable electronic equipment.

    Science.gov (United States)

    Kappler, J. R.; Folsom, A. B.

    1972-01-01

    Maintainability must be designed into long-duration spacecraft and equipment to provide the required high probability of mission success with the least cost and weight. The ability to perform repairs quickly and easily in a space environment can be achieved by imposing specific maintainability design criteria on spacecraft equipment design and installation. A study was funded to investigate and define design criteria for electronic equipment that would permit rapid removal and replacement in a space environment. The results of the study are discussed together with subsequent simulated zero-g demonstration tests of a mockup with new concepts for packaging.

  7. Application of particle damper on electronic packages for spacecraft

    Science.gov (United States)

    Veeramuthuvel, P.; Shankar, K.; Sairajan, K. K.

    2016-10-01

    Particle damping is an effective method of passive vibration control, which is of recent research interest. This paper presents a novel application of particle damper on an electronic package of a spacecraft, tested at ISRO Satellite Centre. The effectiveness of particle damper on the random vibration response of electronic package for spacecraft application exposed to random vibration environments experienced during the launch is studied. The use of particle damper under shock environments are also demonstrated. Optimal particle damper parameters were used based on the design guidelines derived from previous publications of the authors. The comparison of particle damper effectiveness under random vibration loads with respect to the shape of the particle damper capsule and packing ratio are also examined.

  8. Anisotropies of Solar Energetic Electron Events Observed By Multiple Spacecraft

    Science.gov (United States)

    Dresing, N.; Gomez-Herrero, R.; Klassen, A.; Heber, B.; Malandraki, O.; Droege, W.; Kartavykh, Y.

    2014-12-01

    We combine energetic electron observations by the two STEREO spacecraft with ACE measurements at the Earth's longitude to investigate events with wide longitudinal spreads. We scanned the whole STEREO dataset up to mid-2013 and collected 21 of such events. To be counted as a wide-spread event, a minimum longitudinal separation angle of 80 degrees is requested between the source active region at the Sun and the magnetic footpoint of one spacecraft observing the event. Special attention is paid to anisotropies to distinguish different source and transport mechanisms leading to the unexpectedly wide particle spreads. One favorable mechanism is efficient perpendicular transport in the interplanetary medium leading to vanishing anisotropies for larger separation angles. Another scenario is a large particle spread which is performed close to the Sun either due to a coronal shock or due to coronal transport. In this case, the observations at 1 AU during the early phase of the events are expected to show significant anisotropies due to the wide injection range at the Sun and particle focusing during the outwards propagation. For both of the above scenarios we find events in our sample, which suit the expected observations and even further events, which suggest a more complex scenario.

  9. Variations in Cathodoluminescent Intensity of Spacecraft Materials Exposed to Energetic Electron Bombardment

    OpenAIRE

    Dekany, Justin; Christensen, Justin; Dennison, JR; Evans, Amberly; Wilson, Greg; Schneider, Todd; Bowers, Charles W.; Meloy, Robert H.

    2015-01-01

    Various highly insulating materials used in spacecraft construction can exhibit glow (electron-induced luminescence or cathodoluminescence) when exposed to the space plasma environment. Measurements of the absolute and relative cathodoluminescent intensity per incident electron flux of spacecraft materials are essential to predict and mitigate consequences for optical detection and for stray light contamination in space-based observatories. They also provide important information about the ...

  10. Materials Characterization at Utah State University: Facilities and Knowledge-base of Electronic Properties of Materials Applicable to Spacecraft Charging

    Science.gov (United States)

    Dennison, J. R.; Thomson, C. D.; Kite, J.; Zavyalov, V.; Corbridge, Jodie

    2004-01-01

    In an effort to improve the reliability and versatility of spacecraft charging models designed to assist spacecraft designers in accommodating and mitigating the harmful effects of charging on spacecraft, the NASA Space Environments and Effects (SEE) Program has funded development of facilities at Utah State University for the measurement of the electronic properties of both conducting and insulating spacecraft materials. We present here an overview of our instrumentation and capabilities, which are particularly well suited to study electron emission as related to spacecraft charging. These measurements include electron-induced secondary and backscattered yields, spectra, and angular resolved measurements as a function of incident energy, species and angle, plus investigations of ion-induced electron yields, photoelectron yields, sample charging and dielectric breakdown. Extensive surface science characterization capabilities are also available to fully characterize the samples in situ. Our measurements for a wide array of conducting and insulating spacecraft materials have been incorporated into the SEE Charge Collector Knowledge-base as a Database of Electronic Properties of Materials Applicable to Spacecraft Charging. This Database provides an extensive compilation of electronic properties, together with parameterization of these properties in a format that can be easily used with existing spacecraft charging engineering tools and with next generation plasma, charging, and radiation models. Tabulated properties in the Database include: electron-induced secondary electron yield, backscattered yield and emitted electron spectra; He, Ar and Xe ion-induced electron yields and emitted electron spectra; photoyield and solar emittance spectra; and materials characterization including reflectivity, dielectric constant, resistivity, arcing, optical microscopy images, scanning electron micrographs, scanning tunneling microscopy images, and Auger electron spectra. Further

  11. Spacecraft observations and analytic theory of crescent-shaped electron distributions in asymmetric magnetic reconnection

    CERN Document Server

    Egedal, J; Daughton, W; Wetherton, B; Cassak, P A; Chen, L -J; Lavraud, B; Trobert, R B; Dorelli, J; Gershman, D J; Avanov, L A

    2016-01-01

    Supported by a kinetic simulation, we derive an exclusion energy parameter $\\cal{E}_X$ providing a lower kinetic energy bound for an electron to cross from one inflow region to the other during magnetic reconnection. As by a Maxwell Demon, only high energy electrons are permitted to cross the inner reconnection region, setting the electron distribution function observed along the low density side separatrix during asymmetric reconnection. The analytic model accounts for the two distinct flavors of crescent-shaped electron distributions observed by spacecraft in a thin boundary layer along the low density separatrix.

  12. Development and qualification of materials and processes for radiation shielding of Galileo spacecraft electronic components

    International Nuclear Information System (INIS)

    Several materials and processing methods were evaluated for use on the JPL Galileo spacecraft in the area of radiation shielding for electronics. Development and qualification activities involving an aluminum structural laminate are described. These activities included requirements assessment, design tradeoffs, materials selection, adhesive bonding development, mechanical properties measurements, thermal stability assessment, and nondestructive evaluation. This paper presents evaluation of three adhesives for bonding tantalum to aluminum. The concept of combining a thin sheet of tantalum with two outer aluminum face sheets using adhesive bonding was developed successfully. This radiation shield laminate also provides a structural shear plate for mounting electronic assemblies

  13. Possible detection of low energy ions and electrons from planet Mercury by the Helios spacecraft

    International Nuclear Information System (INIS)

    Over the years 1974-1980 there have been several occasions when the Helios' spacecraft have been in the vicinity of the planet Mercury and were connected by interplanetary magnetic field lines to its magnetosphere. We report on one incidence when statistically significant increases (2-5 sigma level) in the proton (E > 80 keV) and electron (E > 60 keV) fluxes are observed coming from the planet and are directed towards the sun. These particles presumably originated from substorm activities in the Hermean magnetosphere or are released from the radiation belts. Solar wind particles accelerated and reflected at the bow shock of Mercury can be excluded

  14. Feasibility Study of Two Candidate Reaction Wheel/thruster Hybrid Control Architecture Designs for the Cassini Spacecraft

    Science.gov (United States)

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

    2012-01-01

    As the first spacecraft to achieve orbit at Saturn in 2004, Cassini has collected science data throughout its four-year prime mission (2004-08), and has since been approved for a first and second extended mission through 2017. Cassini carries a set of three "fixed" reaction wheels and a backup reaction wheel (reaction wheel #4) is mounted on top of an articulable platform. If necessary, this platform could be articulated to orient the backup reaction wheel with the degraded wheel. The reaction wheels are used primarily for attitude control when precise and stable pointing of a science instrument such as the narrow angle camera is required. In 2001-02, reaction wheel #3 exhibited signs of bearing cage instability. As a result, reaction wheel #4 was articulated to align with reaction wheel #3. Beginning in July 2003, Cassini was controlled using wheel #1, #2, and #4. From their first use in the spring of 2000 until today, reaction wheels #1 and #2 have accumulated more than3.5 billions revolutions each. As such, in spite of very carefully management of the wheel spin rates by the mission operation team, there are some observed increases in the drag torque of the wheels' bearings. Hence, the mission operations team must prepare for the contingency scenario in which the reaction wheel #1 (in addition to wheel #3) had degraded. In this hypothetical fault scenario, the two remaining reaction wheels (#2 and #4) will not be able to provide precise and stable three-axis control of the spacecraft. In this study, we evaluate the feasibility of controlling Cassini using the two remaining reaction wheels and four thrusters to meet the science pointing requirements for two key science operational modes: the Optical Remote Sensing and Downlink, Fields, Particles, & Waves operation modes. The performance (e.g., pointing control error, pointing stability, hydrazine consumption rate, etc.) of the hybrid controllers in both operations scenarios will be compared with those achieved

  15. Unexpected spatial intensity distributions and onset timing of solar electron events observed by closely spaced STEREO spacecraft

    Science.gov (United States)

    Klassen, A.; Dresing, N.; Gómez-Herrero, R.; Heber, B.; Müller-Mellin, R.

    2016-09-01

    We present multi-spacecraft observations of four solar electron events using measurements from the Solar Electron Proton Telescope (SEPT) and the Electron Proton Helium INstrument (EPHIN) on board the STEREO and SOHO spacecraft, respectively, occurring between 11 October 2013 and 1 August 2014, during the approaching superior conjunction period of the two STEREO spacecraft. At this time the longitudinal separation angle between STEREO-A (STA) and STEREO-B (STB) was less than 72°. The parent particle sources (flares) of the four investigated events were situated close to, in between, or to the west of the STEREO's magnetic footpoints. The STEREO measurements revealed a strong difference in electron peak intensities (factor ≤12) showing unexpected intensity distributions at 1 AU, although the two spacecraft had nominally nearly the same angular magnetic footpoint separation from the flaring active region (AR) or their magnetic footpoints were both situated eastwards from the parent particle source. Furthermore, the events detected by the two STEREO imply a strongly unexpected onset timing with respect to each other: the spacecraft magnetically best connected to the flare detected a later arrival of electrons than the other one. This leads us to suggest the concept of a rippled peak intensity distribution at 1 AU formed by narrow peaks (fingers) superposed on a quasi-uniform Gaussian distribution. Additionally, two of the four investigated solar energetic particle (SEP) events show a so-called circumsolar distribution and their characteristics make it plausible to suggest a two-component particle injection scenario forming an unusual, non-uniform intensity distribution at 1 AU.

  16. Study of mass loss of spacecraft polymeric thermal control coatings under electron and proton radiations

    Science.gov (United States)

    Khasanshin, Rashid; Novikov, Lev; Galygin, Alexander

    Polymeric composites have a number of properties that give a possibility to apply them as spacecraft external coatings. In space environment, however, such materials become one of the main sources of volatile products that form the outer spacecraft atmosphere and are able to con-dense on contamination-sensitive surfaces of onboard equipment. Thermal control coatings oc-cupy a considerable part of a satellite surface and are mostly subjected to ionizing radiations ac-companying by outgassing. The main stages of the process are the following: formation of vola-tile radiolysis products, diffusion of the products to free material surface, and desorption. Radia-tion-induced destruction and outgassing of material increase its permeability and accelerate mi-gration processes in it. Experimental data of effect of radiation on mass loss of polymeric composites used as thermal control coatings was analyzed and interpreted in the work. As a particular case, it was shown that mass loss of a polymeric composite irradiated by protons is greater than by electrons if energies and flux densities of the particles are the same. It can be explained that volatile products, in the first case, generate within a thin near-surface layer of material which permeability increases together with the absorbed dose, and quickly escape in vacuum. In the second case, a bulk of volatile products emerges far enough from the free surface of material which permeability increases slower as compared with proton radiation. Therefore, migration time of volatile products to the free surface grows and quantity of chemical reactions which they are involved in increases. To analyze and interpret experimental data, a mathematical model describing mass loss of polymeric composites subject to its growth of permeability under radiation is proposed. Based upon analysis of experiments and numerical simulation results, thresholds of fluen-cies and flux densities of electron and proton were determined. Exceeding these

  17. Modification of spacecraft charging and the near-plasma environment caused by the interaction of an artificial electron beam with the earth's upper atmosphere

    DEFF Research Database (Denmark)

    Neubert, Torsten; Banks, P. M.; Gilchrist, B.E.;

    1991-01-01

    V, it is shown that secondary electrons supply a significant contribution to the return current to the spacecraft and thereby reduce the spacecraft potential. Our numerical results are in good agreement with observations from the CHARGE-2 sounding rocket experiment.A more detailed study of the BAI as it relates...

  18. Multi-spacecraft Observations and Transport Modeling of Energetic Electrons for a Series of Solar Particle Events in August 2010

    Science.gov (United States)

    Dröge, W.; Kartavykh, Y. Y.; Dresing, N.; Klassen, A.

    2016-08-01

    During 2010 August a series of solar particle events was observed by the two STEREO spacecraft as well as near-Earth spacecraft. The events, occurring on August 7, 14, and 18, originated from active regions 11093 and 11099. We combine in situ and remote-sensing observations with predictions from our model of three-dimensional anisotropic particle propagation in order to investigate the physical processes that caused the large angular spreads of energetic electrons during these events. In particular, we address the effects of the lateral transport of the electrons in the solar corona that is due to diffusion perpendicular to the average magnetic field in the interplanetary medium. We also study the influence of two coronal mass ejections and associated shock waves on the electron propagation, and a possible time variation of the transport conditions during the above period. For the August 18 event we also utilize electron observations from the MESSENGER spacecraft at a distance of 0.31 au from the Sun for an attempt to separate between radial and longitudinal dependencies in the transport process. Our modelings show that the parallel and perpendicular diffusion mean free paths of electrons can vary significantly not only as a function of the radial distance, but also of the heliospheric longitude. Normalized to a distance of 1 au, we derive values of λ ∥ in the range of 0.15–0.6 au, and values of λ ⊥ in the range of 0.005–0.01 au. We discuss how our results relate to various theoretical models for perpendicular diffusion, and whether there might be a functional relationship between the perpendicular and the parallel mean free path.

  19. Characterization nanoparticles-based vaccines and vaccine candidates: a Transmission Electron Microscopy study

    Directory of Open Access Journals (Sweden)

    I. Menéndez I

    2016-05-01

    Full Text Available Transmission Electron Microscopy (TEM is a valuable tool for the biotech industry. This paper summarizes some of the contributions of MET in the characterization of the recombinant antigens are part of vaccines or vaccine candidates obtained in the CIGB. It mentions the use of complementary techniques MET (Negative staining, and immunoelectron that enhance visualization and ultrastructural characterization of the recombinant proteins obtained by Genetic Engineering.

  20. Surface states and bulk electronic structure in the candidate type-II Weyl semimetal WTe2

    OpenAIRE

    Bruno, F. Y.; Tamai, A.; Wu, Q. S.; Cucchi, I.; Barreteau, C.; A. de la Torre; Walker, S. McKeown; Riccò, S; Wang, Z.; Kim, T K; Hoesch, M.; Shi, M. (Mimi); Plumb, N. C.; Giannini, E; Soluyanov, A. A.

    2016-01-01

    We report angle-resolved photoemission experiments identifying an arc-like surface state connecting the bulk electron and hole pockets of the candidate type-II Weyl semimetal WTe2. This surface state can be isolated clearly on one of two distinct surface terminations observed experimentally, which we associate with the in-equivalent top and bottom surfaces of the non-centrosymmetric crystal structure. We further use the identification of the two different surfaces to clarify the number of bul...

  1. Search for new candidates for the neutrino-oriented mass determination by electron-capture

    CERN Multimedia

    Herfurth, F; Boehm, C; Blaum, K; Beck, D

    2008-01-01

    This proposal is part of an extended program dedicated to the neutrino-mass determination in the electron-capture sector, which aims at ultra-precise mass measurements by Penning traps in combination with cryogenic micro-calorimetry for atomic de-excitation measurements. Here, precise mass measurements with ISOLTRAP are proposed for the orbital electron-capture nuclides $^{194}$Hg and $^{202}$Pb, as well as their daughters, with the goal to determine accurately their Q-values. These values are expected to be the smallest ones among a great variety of known electron-capture precursors. Therefore, these nuclides are strong candidates for an improved electron-neutrino mass determination. We ask for 8 shifts of on-line beam at ISOLDE for mass measurements of $^{194}$Hg, $^{194}$ Au, $^{202}$Pb, and $^{202}$Tl at ISOLTRAP.

  2. The electronic switching spherical array antenna for the Earth Radiation Budget Spacecraft

    Science.gov (United States)

    Kudrna, K.; Hockensmith, R. P.

    1983-01-01

    The ESSA is a microprocessor-controlled antenna for low orbiting spacecraft for telemetry and command relay through the Tracking and Data Relay Satellite System (TDRSS). The array is a hemispherical shape covered with disk radiating elements. A group of radiating elements are continuously selected by the microprocessor controller to form a beam in the direction of a TDRS. A radial switching power divider uses PIN diodes to select the desired radiating elements. The antenna gain is a function of the size of the hemispherical dome. A 30-inch diameter dome is presently being built for the Earth Radiation Budget Spacecraft (ERBS). Gain of this antenna over a hemisphere is 14 dBi and polarization is lefthand circular. There are 145 radiating elements with 12 being used at one time to form a beam. The ESSA subsystem weights 74 pounds and power consumption is 20 watts. RF power handling capability is 30 watts. The S-Band radiating elements have a 10 percent bandwidth that allows simultaneous transmission and reception.

  3. Observations of electron gyroharmonic waves and the structure of the Io torus. [jupiter 1 spacecraft radio astronomy experiment

    Science.gov (United States)

    Birmingham, T. J.; Alexander, J. K.; Desch, M. D.; Hubbard, R. F.; Pedersen, B. M.

    1980-01-01

    Narrow-banded emissions were observed by the Planetary Radio Astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near the upper hybrid resonant frequency, (fuhr) but the distribution of the other observed emissions varies in a systematic way with position in the torus. A refined model of the electron density variation, based on identification of the fuhr line, is included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot losscone electrons. The positioning of the observed auxiliary harmonics with respect to fuhr is shown to be an indicator of the cold to hot temperature ratio. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner and outer portions of the torus.

  4. Increased electric sail thrust through removal of trapped shielding electrons by orbit chaotisation due to spacecraft body

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2009-08-01

    Full Text Available An electric solar wind sail is a recently introduced propellantless space propulsion method whose technical development has also started. The electric sail consists of a set of long, thin, centrifugally stretched and conducting tethers which are charged positively and kept in a high positive potential of order 20 kV by an onboard electron gun. The positively charged tethers deflect solar wind protons, thus tapping momentum from the solar wind stream and producing thrust. The amount of obtained propulsive thrust depends on how many electrons are trapped by the potential structures of the tethers, because the trapped electrons tend to shield the charged tether and reduce its effect on the solar wind. Here we present physical arguments and test particle calculations indicating that in a realistic three-dimensional electric sail spacecraft there exist a natural mechanism which tends to remove the trapped electrons by chaotising their orbits and causing them to eventually collide with the conducting tethers. We present calculations which indicate that if these mechanisms were able to remove trapped electrons nearly completely, the electric sail performance could be about five times higher than previously estimated, about 500 nN/m, corresponding to 1 N thrust for a baseline construction with 2000 km total tether length.

  5. Relativistic electron gas: A candidate for nature's left-handed materials

    Science.gov (United States)

    de Carvalho, C. A. A.

    2016-05-01

    The electric permittivities and magnetic permeabilities for a relativistic electron gas are calculated from quantum electrodynamics at finite temperature and density as functions of temperature, chemical potential, frequency, and wave vector. The polarization and the magnetization depend linearly on both electric and magnetic fields, and are the sum of a zero-temperature and zero-density vacuum part with a temperature- and chemical-potential-dependent medium part. Analytic calculations lead to generalized expressions that depend on three scalar functions. In the nonrelativistic limit, results reproduce the Lindhard formula. In the relativistic case, and in the long wavelength limit, we obtain the following: (i) for ω =0 , generalized susceptibilities that reduce to known nonrelativistic limits; (ii) for ω ≠0 , Drude-type responses at zero temperature. The latter implies that both the electric permittivity ɛ and the magnetic permeability μ may be simultaneously negative, a behavior characteristic of metamaterials. This unambiguously indicates that the relativistic electron gas is one of nature's candidates for the realization of a negative index of refraction system. Moreover, Maxwell's equations in the medium yield the dispersion relation and the index of refraction of the electron gas. Present results should be relevant for plasma physics, astrophysical observations, synchrotrons, and other environments with fast-moving electrons.

  6. Implosion lessons from national security, high reliability spacecraft, electronics, and the forces which changed them

    CERN Document Server

    Temple, L Parker

    2012-01-01

    Implosion is a focused study of the history and uses of high-reliability, solid-state electronics, military standards, and space systems that support our national security and defense. This book is unique in combining the interdependent evolution of and interrelationships among military standards, solid-state electronics, and very high-reliability space systems. Starting with a brief description of the physics that enabled the development of the first transistor, Implosion covers the need for standardizing military electronics, which began during World War II and continu

  7. Optical and Scanning Electron Microscopy of the Materials International Space Station Experiment (MISSE) Spacecraft Silicone Experiment

    Science.gov (United States)

    Hung, Ching-cheh; de Groh, Kim K.; Banks, Bruce A.

    2012-01-01

    Under a microscope, atomic oxygen (AO) exposed silicone surfaces are crazed and seen as "islands" separated by numerous crack lines, much analogous to mud-tile cracks. This research characterized and compared the degree of AO degradation of silicones by analyzing optical microscope images of samples exposed to low Earth orbit (LEO) AO as part of the Spacecraft Silicone Experiment. The Spacecraft Silicone Experiment consisted of eight DC 93-500 silicone samples exposed to eight different AO fluence levels (ranged from 1.46 to 8.43 10(exp 21) atoms/sq cm) during two different Materials International Space Station Experiment (MISSE) missions. Image analysis software was used to analyze images taken using a digital camera. To describe the morphological degradation of each AO exposed flight sample, three different parameters were selected and estimated: (1) average area of islands was determined and found to be in the 1000 to 3100 sq mm range; (2) total length of crack lines per unit area of the sample surface were determined and found to be in the range of 27 to 59 mm of crack length per sq mm of sample surface; and (3) the fraction of sample surface area that is occupied by crack lines was determined and found to be in the 25 to 56 percent range. In addition, average crack width can be estimated from crack length and crack area measurements and was calculated to be about 10 mm. Among the parameters studied, the fraction of sample surface area that is occupied by crack lines is believed to be most useful in characterizing the degree of silicone conversion to silicates by AO because its value steadily increases with increasing fluence over the entire fluence range. A series of SEM images from the eight samples exposed to different AO fluences suggest a complex sequence of surface stress due to surface shrinkage and crack formation, followed by re-distribution of stress and shrinking rate on the sample surface. Energy dispersive spectra (EDS) indicated that upon AO

  8. Automated determination of electron density from electric field measurements on the Van Allen Probes spacecraft

    Science.gov (United States)

    Zhelavskaya, Irina; Kurth, William; Spasojevic, Maria; Shprits, Yuri

    2016-07-01

    We present the Neural-network-based Upper-hybrid Resonance Determination (NURD) algorithm for automatic inference of the electron number density from plasma wave measurements made onboard NASA's Van Allen Probes mission. A feedforward neural network is developed to determine the upper hybrid resonance frequency, f_{uhr}, from electric field measurements, which is then used to calculate the electron number density. In previous missions, the plasma resonance bands were manually identified, and there have been few attempts to do robust, routine automated detections. We describe the design and implementation of the algorithm and perform an initial analysis of the resulting electron number density distribution obtained by applying NURD to 2.5 years of data collected with the EMFISIS instrumentation suite of the Van Allen Probes mission. Densities obtained by NURD are compared to those obtained by another recently developed automated technique and also to an existing empirical plasmasphere and trough density model.

  9. Electron Beam Freeform Fabrication: A Fabrication Process that Revolutionizes Aircraft Structural Designs and Spacecraft Supportability

    Science.gov (United States)

    Taminger, Karen M.

    2008-01-01

    The technological inception and challenges, as well as current applications of the electron beam freeform fabrication (EBF3) process are outlined. The process was motivated by the need for a new metals technology that would be cost-effective, enable the production of new alloys and that would could be used for efficient, lightweight structures. EBF3 is a rapid metal fabrication, layer-additive process that uses no molds or tools and which yields properties equivalent to wrought. The benefits of EBF3 include it near-net shape which minimizes scrap and reduces part count; efficiency in design which allows for lighter weight and enhanced performance; and, its "green" manufacturing process which yields minimal waste products. EBF3 also has a high tensile strength, while a structural test comparison found that EBF3 panels performed 5% lower than machined panels. Technical challenges in the EBF3 process include a need for process control monitoring and an improvement in localized heat response. Currently, the EBF3 process can be used to add details onto forgings and to construct and form complex shapes. However, it has potential uses in a variety of industries including aerospace, automotive, sporting goods and medical implant devices. The novel structural design capabilities of EBF3 have the ability to yield curved stiffeners which may be optimized for performance, low weight, low noise and damage tolerance applications. EBF3 has also demonstrated its usefulness in 0-gravity environments for supportability in space applications.

  10. Spacecraft sterilization.

    Science.gov (United States)

    Kalfayan, S. H.

    1972-01-01

    Spacecraft sterilization is a vital factor in projects for the successful biological exploration of other planets. The microorganisms of major concern are the fungi and bacteria. Sterilization procedures are oriented toward the destruction of bacterial spores. Gaseous sterilants are examined, giving attention to formaldehyde, beta-propiolactone, ethylene oxide, and the chemistry of the bactericidal action of sterilants. Radiation has been seriously considered as another method for spacecraft sterilization. Dry heat sterilization is discussed together with the effects of ethylene oxide decontamination and dry heat sterilization on materials.

  11. Electronic Portfolios in Teacher Education: A Case Study of Early Childhood Teacher Candidates

    Science.gov (United States)

    Ntuli, Esther; Keengwe, Jared; Kyei-Blankson, Lydia

    2009-01-01

    The use of electronic portfolios is increasingly becoming popular in teacher education programs. The electronic portfolio allows learners to express their work and take ownership over their own ability to plan and assess and reflect upon their learning during a specific period of time. While many teacher education programs have adopted electronic…

  12. Analysis of Surface Charging for a Candidate Solar Sail Mission Using Nascap-2k

    Science.gov (United States)

    Parker, Linda Neergaard; Minow, Joseph I.; Davis, Victoria; Mandell, Myron; Gardner, Barbara

    2005-01-01

    The characterization of the electromagnetic interaction for a solar sail in the solar wind environment and identification of viable charging mitigation strategies are critical solar sail mission design task. Spacecraft charging has important implications both for science applications and for lifetime and reliability issues of sail propulsion systems. To that end, surface charging calculations of a candidate 150-meter-class solar sail spacecraft for the 0.5 AU solar polar and 1.0 AU L1 solar wind environments are performed. A model of the spacecraft with candidate materials having appropriate electrical properties is constructed using Object Toolkit. The spacecraft charging analysis is performed using Nascap-2k, the NASA/AFRL sponsored spacecraft charging analysis tool. Nominal and atypical solar wind environments appropriate for the 0.5 AU and 1.0 AU missions are used to establish current collection of solar wind ions and electrons. Finally, a geostationary orbit environment case is included to demonstrate a bounding example of extreme (negative) charging of a solar sail spacecraft. Results from the charging analyses demonstrate that minimal differential potentials (and resulting threat of electrostatic discharge) occur when the spacecraft is constructed entirely of conducting materials, as anticipated from standard guidelines for mitigation of spacecraft charging issues. Examples with dielectric materials exposed to the space environment exhibit differential potentials ranging from a few volts to extreme potentials in the kilovolt range.

  13. 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).

  14. Bulk and surface electron transport in topological insulator candidate YbB{sub 6-δ}

    Energy Technology Data Exchange (ETDEWEB)

    Glushkov, Vladimir V.; Demishev, Sergey V.; Sluchanko, Nikolay E. [Prokhorov General Physics Institute of RAS, Vavilov str. 38, 119991, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Institutskii per. 9, 141700, Dolgoprudny, Moscow Region (Russian Federation); Bozhko, Alexey D.; Bogach, Alexey V.; Semeno, Alexey V.; Voronov, Valeriy V. [Prokhorov General Physics Institute of RAS, Vavilov str. 38, 119991, Moscow (Russian Federation); Dukhnenko, Anatoliy V.; Filipov, Volodimir B.; Shitsevalova, Natalya Yu. [Frantsevich Institute for Problems of Materials Science NAS, Krzhyzhanovsky str. 3, 03680, Kiev (Ukraine); Kondrin, Mikhail V. [Vereshchagin Institute of High Pressure Physics of RAS, 142190, Troitsk, Moscow (Russian Federation); Kuznetsov, Alexey V.; Sannikov, Ilia I. [National Research Nuclear University ' ' MEPhI' ' , Kashirskoe Shosse 31, 115409, Moscow (Russian Federation)

    2016-04-15

    We report the study of transport and magnetic properties of the YbB{sub 6-δ}single crystals grown by inductive zone melting. A strong disparity in the low temperature resistivity, Seebeck and Hall coefficients is established for the samples with the different level of boron deficiency. The effective parameters of the charge transport in YbB{sub 6-δ} are shown to depend on the concentration of intrinsic defects, which is estimated to range from 0.09% to 0.6%. The pronounced variation of Hall mobility μ{sub H} found for bulk holes is induced by the decrease of transport relaxation time from τ ∼ 7.7 fs for YbB{sub 5.994} to τ ∼ 2.2 fs for YbB{sub 5.96}. An extra contribution to conductivity from electrons with μ{sub H}∼ -1000 cm{sup 2} V{sup -1} s{sup -1} and the very low concentration n /n{sub Yb}∼ 10{sup -6} discovered below 20 K for all the single crystals under investigation is suggested to arise from the surface electron states appeared in the inversion layer due to the band bending. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. 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 (electronics, advanced manufacturing for lightweight structures, and innovative propulsion are making it possible to fly much more capable micro spacecraft for planetary exploration. While micro spacecraft, such as CubeSats, offer significant cost reductions with added capability from advancing technologies, the technical challenges for deep space missions are very different than for missions conducted in low Earth orbit. Micro spacecraft must be able to sustain a broad range of planetary environments (i.e., radiations, temperatures, limited power generation) and offer long-range telecommunication performance on a par with science needs. Other capabilities needed for planetary missions, such as fine 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.

  16. The relativistic electron plasma: a candidate for nature's left-handed material

    CERN Document Server

    de Carvalho, C A A

    2015-01-01

    The electric permittivities and magnetic permeabilities for a relativistic electron gas are calculated from quantum electrodynamics at finite temperature and density as functions of temperature, chemical potential, frequency, and wavevector. The polarization and the magnetization depend linearly on both electric and magnetic fields, and are the sum of a zero-temperature and zero-density vacuum part with a temperature- and chemical potential-dependent medium part. Analytic calculations lead to generalized expressions that depend on three scalar functions. In the nonrelativistic limit, results reproduce the Lindhard formula. In the relativistic case, and in the long wavelength limit, we obtain: i) for $\\omega=0$, generalized susceptibilities that reduce to known nonrelativistic limits; ii) for $\\omega \

  17. Component-Level Electronic-Assembly Repair (CLEAR) Spacecraft Circuit Diagnostics by Analog and Complex Signature Analysis

    Science.gov (United States)

    Oeftering, Richard C.; Wade, Raymond P.; Izadnegahdar, Alain

    2011-01-01

    The Component-Level Electronic-Assembly Repair (CLEAR) project at the NASA Glenn Research Center is aimed at developing technologies that will enable space-flight crews to perform in situ component-level repair of electronics on Moon and Mars outposts, where there is no existing infrastructure for logistics spares. These technologies must provide effective repair capabilities yet meet the payload and operational constraints of space facilities. Effective repair depends on a diagnostic capability that is versatile but easy to use by crew members that have limited training in electronics. CLEAR studied two techniques that involve extensive precharacterization of "known good" circuits to produce graphical signatures that provide an easy-to-use comparison method to quickly identify faulty components. Analog Signature Analysis (ASA) allows relatively rapid diagnostics of complex electronics by technicians with limited experience. Because of frequency limits and the growing dependence on broadband technologies, ASA must be augmented with other capabilities. To meet this challenge while preserving ease of use, CLEAR proposed an alternative called Complex Signature Analysis (CSA). Tests of ASA and CSA were used to compare capabilities and to determine if the techniques provided an overlapping or complementary capability. The results showed that the methods are complementary.

  18. Xenia Spacecraft Study Addendum: Spacecraft Cost Estimate

    Science.gov (United States)

    Hill, Spencer; Hopkins, Randall

    2009-01-01

    This slide presentation reviews the Xenia spacecraft cost estimates as an addendum for the Xenia Spacecraft study. The NASA/Air Force Cost model (NAFCPOM) was used to derive the cost estimates that are expressed in 2009 dollars.

  19. Pointing compensation system for spacecraft instruments

    Science.gov (United States)

    Plescia, Carl T. (Inventor); Gamble, Donald W. (Inventor)

    1987-01-01

    A closed loop system reduces pointing errors in one or more spacecraft instruments. Associated with each instrument is a electronics package (3) for commanding motion in that instrument and a pointing control system (5) for imparting motion in that instrument in response to a command (4) from the commanding package (3). Spacecraft motion compensation logic (25) compensates for instrument pointing errors caused by instrument-motion-induced spacecraft motion. Any finite number of instruments can be so compensated, by providing each pointing control system (5) and each commanding package (3), for the instruments desired to be compensated, with a link to the spacecraft motion compensation logic (25). The spacecraft motion compensation logic (25) is an electronic manifestation of the algebraic negative of a model of the dynamics of motion of the spacecraft. An example of a suitable model, and computer-simulated results, are presented.

  20. Computer simulation of spacecraft/environment interaction.

    Science.gov (United States)

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

    1999-10-01

    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.

  1. 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.

  2. 航天器综合电子系统通用测试系统设计%Universal test system design for the spacecraft electronic system

    Institute of Scientific and Technical Information of China (English)

    李姗; 骆培; 安军社

    2014-01-01

    This paper proposes a scalable, reconfigurable, general test system design oriented the spacecraft electronic system. The design employs open flexible test system design method. Common test interfaces are integrated into classified modules with FPGA as control core, which ensures the reconfigurability of hardware. Software utilizes modularized pattern. Application program interacts with the operating system through transfer layer which ensures reusability of software. All modules can be combined into three local testing machine models using the PC/104 PLUS and Ethernet. The optical fiber transmission technology is employed to combine all the local testing machine models into a distributed testing system. This system is compatible, universal, and secure. Vacuum tank test and multi-device joint test show that the system is competent for all kinds of electronic system testing in different scenarios.%提出了一种接口丰富、可重构扩展的模块化通用测试系统方案。引入开放式柔性测试系统设计方法,基础测试模块使用FPGA作为控制核心,以保证系统硬件柔性化;系统软件采用分层模块化方法设计,通过转换层统一操作系统的接口,以保证系统软件柔性化。并应用PC/104 PLUS与以太网两种总线技术,将测试模块灵活组合成3种本地测试节点模型。本地测试设备以节点的形式通过光纤网络接入测试系统,实现分布式测试系统网络,增强系统兼容性与应用范围,同时保证数据传输安全。真空罐测试和多设备联合测试实验表明该系统有能力适应不同型号任务、不同阶段、不同测试场景的综合电子系统测试工作。

  3. Simulating spacecraft systems

    CERN Document Server

    Eickhoff, Jens

    2009-01-01

    This book on the application of functional system simulation in spacecraft development covers the entire process from spacecraft design to final verification. It offers the latest research in all relevant topics and includes numerous examples.

  4. The ISO Spacecraft

    Science.gov (United States)

    Ximenez de Ferrin, S.

    1995-11-01

    ESA's Infrared Space Observatory (ISO) consists of two modules: the Payload module, which includes the telescope and the scientific instruments, and the Service Module, which houses the instruments electronics, the hydrazine propellant tank and all other classical spacecraft subsystems. To ensure that the telescope is kept near absolute zero and thus is the least disturbed by the effects of the infrared emissions from other elements of the system, the telescope is enclosed in a helium-cooled cryostat. The cryostat in turn is shaded by a Sun-shield to protect it from the heat of the direct Sun. The shield has a covering of solar cells that provide the electrical power needed for the mission.

  5. Internet Access to Spacecraft

    OpenAIRE

    Rash, James; Parise, Ron; Hogie, Keith; Criscuolo, Ed; Langston, Jim; Jackson, Chris; Price, Harold

    2000-01-01

    The Operating Missions as Nodes on the Internet (OMNI) project at NASA's Goddard Space flight Center (GSFC), is demonstrating the use of standard Internet protocols for spacecraft communication systems. This year, demonstrations of Internet access to a flying spacecraft have been performed with the UoSAT-12 spacecraft owned and operated by Surrey Satellite Technology Ltd. (SSTL). Previously, demonstrations were performed using a ground satellite simulator and NASA's Tracking and Data Relay Sa...

  6. 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...

  7. Spacecraft camera image registration

    Science.gov (United States)

    Kamel, Ahmed A. (Inventor); Graul, Donald W. (Inventor); Chan, Fred N. T. (Inventor); Gamble, Donald W. (Inventor)

    1987-01-01

    A system for achieving spacecraft camera (1, 2) image registration comprises a portion external to the spacecraft and an image motion compensation system (IMCS) portion onboard the spacecraft. Within the IMCS, a computer (38) calculates an image registration compensation signal (60) which is sent to the scan control loops (84, 88, 94, 98) of the onboard cameras (1, 2). At the location external to the spacecraft, the long-term orbital and attitude perturbations on the spacecraft are modeled. Coefficients (K, A) from this model are periodically sent to the onboard computer (38) by means of a command unit (39). The coefficients (K, A) take into account observations of stars and landmarks made by the spacecraft cameras (1, 2) themselves. The computer (38) takes as inputs the updated coefficients (K, A) plus synchronization information indicating the mirror position (AZ, EL) of each of the spacecraft cameras (1, 2), operating mode, and starting and stopping status of the scan lines generated by these cameras (1, 2), and generates in response thereto the image registration compensation signal (60). The sources of periodic thermal errors on the spacecraft are discussed. The system is checked by calculating measurement residuals, the difference between the landmark and star locations predicted at the external location and the landmark and star locations as measured by the spacecraft cameras (1, 2).

  8. 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.

  9. Higgs boson candidate event from 2012 data (8 TeV) recorded by the CMS experiment: ZZ to four electrons

    CERN Multimedia

    2016-01-01

    Event recorded with the CMS detector in 2012 at a proton-proton centre of mass energy of 8 TeV. The event shows characteristics expected from the decay of the SM Higgs boson to a pair of Z bosons, both of which subsequently decay to a pair of electrons. The event could also be due to known standard model background processes.

  10. Research on Spacecraft Illumination

    Directory of Open Access Journals (Sweden)

    Bo Cai

    2011-07-01

    Full Text Available Illumination analysis of spacecraft is very important. This paper firstly introduces the importance of spacecraft illumination analysis in aerospace fields and points out that illumination conditions will influence the design of shape of spacecraft body and the installation of spacecraft equipments. Then, it discusses two methods for analyzing spacecraft solar-panel shadow and illumination conditions: ray tracing illumination algorithm and polyhedral mesh contour edge projection algorithm and compares their efficiency and feasibility. Shadow area and solar area are computed of every cell on solar panels. We designed solar panel single-axis rotation experiment to validate the proposed algorithm. The experimental results show that contour edge projection algorithm has fine accuracy and costs less time. For detailed illumination information, we apply a practical segment clipping algorithm after some comparisons.

  11. Printed Spacecraft Separation System

    Energy Technology Data Exchange (ETDEWEB)

    Holmans, Walter [Planetary Systems Corporation, Silver Springs, MD (United States); Dehoff, Ryan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    In this project Planetary Systems Corporation proposed utilizing additive manufacturing (3D printing) to manufacture a titanium spacecraft separation system for commercial and US government customers to realize a 90% reduction in the cost and energy. These savings were demonstrated via “printing-in” many of the parts and sub-assemblies into one part, thus greatly reducing the labor associated with design, procurement, assembly and calibration of mechanisms. Planetary Systems Corporation redesigned several of the components of the separation system based on additive manufacturing principles including geometric flexibility and the ability to fabricate complex designs, ability to combine multiple parts of an assembly into a single component, and the ability to optimize design for specific mechanical property targets. Shock absorption was specifically targeted and requirements were established to attenuate damage to the Lightband system from shock of initiation. Planetary Systems Corporation redesigned components based on these requirements and sent the designs to Oak Ridge National Laboratory to be printed. ORNL printed the parts using the Arcam electron beam melting technology based on the desire for the parts to be fabricated from Ti-6Al-4V based on the weight and mechanical performance of the material. A second set of components was fabricated from stainless steel material on the Renishaw laser powder bed technology due to the improved geometric accuracy, surface finish, and wear resistance of the material. Planetary Systems Corporation evaluated these components and determined that 3D printing is potentially a viable method for achieving significant cost and savings metrics.

  12. Spacecraft dielectric material properties and spacecraft charging

    Science.gov (United States)

    Frederickson, A. R.; Wall, J. A.; Cotts, D. B.; Bouquet, F. L.

    1986-01-01

    The physics of spacecraft charging is reviewed, and criteria for selecting and testing semiinsulating polymers (SIPs) to avoid charging are discussed and illustrated. Chapters are devoted to the required properties of dielectric materials, the charging process, discharge-pulse phenomena, design for minimum pulse size, design to prevent pulses, conduction in polymers, evaluation of SIPs that might prevent spacecraft charging, and the general response of dielectrics to space radiation. SIPs characterized include polyimides, fluorocarbons, thermoplastic polyesters, poly(alkanes), vinyl polymers and acrylates, polymers containing phthalocyanine, polyacene quinones, coordination polymers containing metal ions, conjugated-backbone polymers, and 'metallic' conducting polymers. Tables summarizing the results of SIP radiation tests (such as those performed for the NASA Galileo Project) are included.

  13. Spectrum of allergenic pollen in Karachi and their characterization using conventional and electron microscopy: Potential candidates for allergy vaccines

    International Nuclear Information System (INIS)

    Objective: To study the distribution of naturally growing plants with possible allergenic potential and study their pollen morphology in Karachi, Pakistan. Methodology: We performed field surveys of naturally growing plants with possible allergenic potential and studied their pollen morphology using conventional (light) as well as scanning electron microscopy. Results: About 80 allergenic pollen producing species were identified which are distributed in 45 genera and 9 angiospermic families. Grasses belonging to Graminae are most abundant followed by plants from family Fabaceae (Leguminosae). Highly allergenic weeds were also found widely growing in the city areas belonging to Amaranthaceae/Chenopodiaceae family. Conclusion: Our study provides an updated information about the allergenic plants growing in Karachi city. All desensitization efforts should be designed in accordance to the available information regarding the prevalent allergens in the environment so that appropriate therapy can be given to the affected population. (author)

  14. 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...

  15. Spacecraft Power Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project will develop the Spacecraft Power Monitor (SPM) which will use non-intrusive electrical monitoring (NEMO). NEMO transforms the power...

  16. 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 ...

  17. Spacecraft transformer and inductor design

    Science.gov (United States)

    Mclyman, W. T.

    1977-01-01

    The conversion process in spacecraft power electronics requires the use of magnetic components which frequently are the heaviest and bulkiest items in the conversion circuit. This handbook pertains to magnetic material selection, transformer and inductor design tradeoffs, transformer design, iron core dc inductor design, toroidal power core inductor design, window utilization factors, regulation, and temperature rise. Relationships are given which simplify and standardize the design of transformers and the analysis of the circuits in which they are used. The interactions of the various design parameters are also presented in simplified form so that tradeoffs and optimizations may easily be made.

  18. Orbital spacecraft resupply technology

    Science.gov (United States)

    Eberhardt, R. N.; Tracey, T. R.; Bailey, W. J.

    1986-01-01

    The resupplying of orbital spacecraft using the Space Shuttle, Orbital Maneuvering Vehicle, Orbital Transfer Vehicle or a depot supply at a Space Station is studied. The governing factor in fluid resupply designs is the system size with respect to fluid resupply quantities. Spacecraft propellant management for tankage via diaphragm or surface tension configurations is examined. The capabilities, operation, and application of adiabatic ullage compression, ullage exchange, vent/fill/repressurize, and drain/vent/no-vent fill/repressurize, which are proposed transfer methods for spacecraft utilizing tankage configurations, are described. Selection of the appropriate resupply method is dependent on the spacecraft design features. Hydrazine adiabatic compression/detonation, liquid-free vapor venting to prevent freezing, and a method for no-vent liquid filling are analyzed. Various procedures for accurate measurements of propellant mass in low gravity are evaluated; a system of flowmeters with a PVT system was selected as the pressurant solubility and quantity gaging technique. Monopropellant and bipropellant orbital spacecraft consumable resupply system tanks which resupply 3000 lb of hydrazine and 7000 lb of MMH/NTO to spacecraft on orbit are presented.

  19. Ingot niobium as candidate electrode material for Jefferson Lab 200 kV inverted electron photogun

    Energy Technology Data Exchange (ETDEWEB)

    BastaniNejad, Mahzad, E-mail: Mahzad@jlab.org [Christopher Newport University, Newport News VA (United States); Suleiman, Riad, E-mail: suleiman@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

    2015-12-04

    This contribution describes the field emission characterization of niobium electrodes using a DC high voltage field emission test apparatus. A total of six electrodes were evaluated: two large-grain, two single-crystal, and two fine-grain that were chemically polished using a buffered-chemical acid solution. Field emission from niobium electrodes could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode is biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (<10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18.7 MV/m. Motivated by these results, an inverted electron photogun operated at Jefferson Lab injector test facility was equipped with a large-grain niobium cathode electrode and it has been successfully conditioned to 225 kV without field emission. This photogun was used to study strained superlattice GaAs and K{sub 2}CsSb photocathodes at high beam currents.

  20. Ingot niobium as candidate electrode material for Jefferson Lab 200 kV inverted electron photogun

    International Nuclear Information System (INIS)

    This contribution describes the field emission characterization of niobium electrodes using a DC high voltage field emission test apparatus. A total of six electrodes were evaluated: two large-grain, two single-crystal, and two fine-grain that were chemically polished using a buffered-chemical acid solution. Field emission from niobium electrodes could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode is biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (<10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18.7 MV/m. Motivated by these results, an inverted electron photogun operated at Jefferson Lab injector test facility was equipped with a large-grain niobium cathode electrode and it has been successfully conditioned to 225 kV without field emission. This photogun was used to study strained superlattice GaAs and K2CsSb photocathodes at high beam currents

  1. Low-Temperature Spacecraft: Challenges/Opportunities

    Science.gov (United States)

    Dickman, J. E.; Patterson, R. L.; Overton, E.; Hammoud, A. N.; Gerber, S. S.

    2001-01-01

    Imagine sending a spacecraft into deep space that operates at the ambient temperature of its environment rather than hundreds of degrees Kelvin warmer. The average temperature of a spacecraft warmed only by the sun drops from 279 K near the Earth's orbit to 90 K near the orbit of Saturn, and to 44 K near Pluto's orbit. At present, deep space probes struggle to maintain an operating temperature near 300 K for the onboard electronics. To warm the electronics without consuming vast amounts of electrical energy, radioisotope heater units (RHUs) are used in vast numbers. Unfortunately, since RHU are always 'on', an active thermal management system is required to reject the excess heat. A spacecraft designed to operate at cryogenic temperatures and shielded from the sun by a large communication dish or solar cell array could be less complex, lighter, and cheaper than current deep space probes. Before a complete low-temperature spacecraft becomes a reality, there are several challenges to be met. Reliable cryogenic power electronics is one of the major challenges. The Low-Temperature Power Electronics Research Group at NASA Glenn Research Center (GRC) has demonstrated the ability of some commercial off the shelf power electronic components to operate at temperatures approaching that of liquid nitrogen (77 K). Below 77 K, there exists an opportunity for the development of reliable semiconductor power switching technologies other than bulk silicon CMOS. This paper will report on the results of NASA GRC's Low-Temperature Power Electronics Program and discuss the challenges to (opportunities for) the creation of a low-temperature spacecraft.

  2. Electron pitch angle variations recorded at the high magnetic latitude boundary layer by the NUADU instrument on the TC-2 spacecraft

    Directory of Open Access Journals (Sweden)

    L. Lu

    2005-11-01

    Full Text Available The NUADU (NeUtral Atom Detector Unit experiment aboard TC-2 recorded, with high temporal and spatial resolution, 4π solid angle images of electrons (~50-125 keV spiraling around geomagnetic field lines at high northern magnetic latitudes (L>10, during its in-orbit commissioning phase (September 2004. The ambient magnetic field, as well as electrons in other energy ranges, were simultaneously measured by the TC-2 magnetometer (FGM, the plasma electron and current experiment (PEACE, the low energy ion detector (LEID and the high energy electron detector (HEED. The NUADU data showed that up-flowing electron beams could form "ring-like" and "dumbbell-type" pitch angle distributions (PADs in the region sampled. Changes in these pitch angle distributions due to transient magnetic variations are suggested to have been associated with electron acceleration along the geomagnetic field lines. A nested magnetic bottle configuration that formed due to the propagation towards the Earth of a magnetic pulse, is proposed to have been associated with this process.

  3. Heat capacity mapping radiometer for AEM spacecraft

    Science.gov (United States)

    Sonnek, G. E.

    1977-01-01

    The operation, maintenance, and integration of the applications explorer mission heat capacity mapping radiometer is illustrated in block diagrams and detail schematics of circuit functions. Data format and logic timing diagrams are included along with radiometric and electronic calibration data. Mechanical and electrical configuration is presented to provide interface details for integration of the HCMR instrument to AEM spacecraft.

  4. 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.

  5. Spacecraft Radiation Analysis

    Science.gov (United States)

    Harris, D. W.

    1972-01-01

    The radiation interface in spacecrafts using radioisotope thermoelectric generators is studied. A Monte Carlo analysis of the radiation field that includes scattered radiation effects, produced neutron and gamma photon isoflux contours as functions of distance from the RTG center line. It is shown that the photon flux is significantly depressed in the RTG axial direction because of selfshielding. Total flux values are determined by converting the uncollided flux values into an equivalent RTG surface source and then performing a Monte Carlo analysis for each specific dose point. Energy distributions of the particle spectra completely define the radiation interface for a spacecraft model.

  6. Intelligent spacecraft module

    Science.gov (United States)

    Oungrinis, Konstantinos-Alketas; Liapi, Marianthi; Kelesidi, Anna; Gargalis, Leonidas; Telo, Marinela; Ntzoufras, Sotiris; Paschidi, Mariana

    2014-12-01

    The paper presents the development of an on-going research project that focuses on a human-centered design approach to habitable spacecraft modules. It focuses on the technical requirements and proposes approaches on how to achieve a spatial arrangement of the interior that addresses sufficiently the functional, physiological and psychosocial needs of the people living and working in such confined spaces that entail long-term environmental threats to human health and performance. Since the research perspective examines the issue from a qualitative point of view, it is based on establishing specific relationships between the built environment and its users, targeting people's bodily and psychological comfort as a measure toward a successful mission. This research has two basic branches, one examining the context of the system's operation and behavior and the other in the direction of identifying, experimenting and formulating the environment that successfully performs according to the desired context. The latter aspect is researched upon the construction of a scaled-model on which we run series of tests to identify the materiality, the geometry and the electronic infrastructure required. Guided by the principles of sensponsive architecture, the ISM research project explores the application of the necessary spatial arrangement and behavior for a user-centered, functional interior where the appropriate intelligent systems are based upon the existing mechanical and chemical support ones featured on space today, and especially on the ISS. The problem is set according to the characteristics presented at the Mars500 project, regarding the living quarters of six crew-members, along with their hygiene, leisure and eating areas. Transformable design techniques introduce spatial economy, adjustable zoning and increased efficiency within the interior, securing at the same time precise spatial orientation and character at any given time. The sensponsive configuration is

  7. Single reusable spacecraft

    Data.gov (United States)

    National Aeronautics and Space Administration — Design of a my single person reusable spacecraft. It can carry one person and it has to be dropped from an aircraft at an altitude of 40,000 - 45,000 feet. Can be...

  8. A Self-Regulating Freezable Heat Exchanger for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A spacecraft thermal control system must keep the cabin (both air and its structure if manned) and electronic equipment within a narrow temperature range even...

  9. Nanocomposites in Multifuntional Structures for Spacecraft Platforms

    Science.gov (United States)

    Marcos, J.; Mendizabal, M.; Elizetxea, C.; Florez, S.; Atxaga, G.; Del Olmo, E.

    2012-07-01

    The integration of functionalities as electrical, thermal, power or radiation shielding inside carrier electronic boxes, solar panels or platform structures allows reducing weight, volume, and harness for spacecraft. The multifunctional structures represent an advanced design approach for space components and subsystems. The development of such multifunctional structures aims the re-engineering traditional metallic structures by composites in space, which request to provide specific solutions for thermal conductivity, EMI-EMC, radiation shielding and integration. The use of nanomaterials as CNF and nano-adds to reinforce composite structures allows obtaining local solutions for improving electrical conductivity, thermal conductivity and radiation shielding. The paper summarises the results obtained in of three investigations conducted by Tecnalia based on carbon nanofillers for improving electro-thermal characteristics of spacecraft platform, electronic substrates and electronics boxes respectively.

  10. SPASIM: A Spacecraft Simulator

    Science.gov (United States)

    Liceaga, Carlos A.

    1997-01-01

    The SPAcecraft SIMulator (SPASIM) simulates the functions and resources of a spacecraft to quickly perform conceptual design (Phase A) trade-off and sensitivity analyses and uncover any operational bottlenecks during any part of the mission. Failure modes and operational contingencies can be evaluated allowing operational planning (what-if scenarios) and optimization for a range of mission scenarios. The payloads and subsystems are simulated, using a hierarchy of graphical models, in terms of how their functions affect resources such as propellant, power, and data. Any of the inputs and outputs of the payloads and subsystems can be plotted during the simulation or stored in a file so they can be used by other programs. Most trade-off analyses, including those that compare current versus advanced technology, can be performed by changing values in the parameter menus. However, when a component is replaced by one with a different functional architecture, its graphical model can also be modified or replaced by drawing from a component library. SPASIM has been validated using several spacecraft designs that were at least at the Critical Design Review level. The user and programmer guide, including figures, is available on line as a hypertext document. This is an easy-to-use and expandable tool which is based on MATLAB(R) and SIMULINK(R). It runs on Silicon Graphics Inc. workstations and personal computers with Windows 95(TM) or NT(TM).

  11. Topology Control Algorithms for Spacecraft Formation Flying Networks Under Connectivity and Time-Delay Constraints Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SSCI is proposing to develop a set of topology control algorithms for a formation flying spacecraft that can be used to design and evaluate candidate formation...

  12. Using a Genetic Algorithm to Design Nuclear Electric Spacecraft

    Science.gov (United States)

    Pannell, William P.

    2003-01-01

    The basic approach to to design nuclear electric spacecraft is to generate a group of candidate designs, see how "fit" the design are, and carry best design forward to the next generation. Some designs eliminated, some randomly modified and carried forward.

  13. Five kepler target stars that show multiple transiting exoplanet candidates

    DEFF Research Database (Denmark)

    Steffen..[], Jason H.; Batalha, N. M.; Broucki, W J.;

    2010-01-01

    We present and discuss five candidate exoplanetary systems identified with the Kepler spacecraft. These five systems show transits from multiple exoplanet candidates. Should these objects prove to be planetary in nature, then these five systems open new opportunities for the field of exoplanets...

  14. Spacecraft Electrostatic Radiation Shielding

    Science.gov (United States)

    2008-01-01

    This project analyzed the feasibility of placing an electrostatic field around a spacecraft to provide a shield against radiation. The concept was originally proposed in the 1960s and tested on a spacecraft by the Soviet Union in the 1970s. Such tests and analyses showed that this concept is not only feasible but operational. The problem though is that most of this work was aimed at protection from 10- to 100-MeV radiation. We now appreciate that the real problem is 1- to 2-GeV radiation. So, the question is one of scaling, in both energy and size. Can electrostatic shielding be made to work at these high energy levels and can it protect an entire vehicle? After significant analysis and consideration, an electrostatic shield configuration was proposed. The selected architecture was a torus, charged to a high negative voltage, surrounding the vehicle, and a set of positively charged spheres. Van de Graaff generators were proposed as the mechanism to move charge from the vehicle to the torus to generate the fields necessary to protect the spacecraft. This design minimized complexity, residual charge, and structural forces and resolved several concerns raised during the internal critical review. But, it still is not clear if such a system is costeffective or feasible, even though several studies have indicated usefulness for radiation protection at energies lower than that of the galactic cosmic rays. Constructing such a system will require power supplies that can generate voltages 10 times that of the state of the art. Of more concern is the difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge. Yet, if these concerns can be resolved, such a scheme may provide significant radiation shielding to future vehicles, without the excessive weight or complexity of other active shielding techniques.

  15. Furlable spacecraft antenna development

    Science.gov (United States)

    Oliver, R. E.; Wilson, A. H.

    1972-01-01

    The development of large furlable spacecraft antennas using conical main reflectors is described. Two basic antenna configurations which utilize conical main reflectors have been conceived and are under development. In the conical-Gregorian configuration each ray experiences two reflections in traveling from the feed center to the aperture plane. In the Quadreflex (four reflection) configuration, each ray experiences four reflections, one at each of two subreflector surfaces and two at the main conical reflector surface. The RF gain measurements obtained from 6-ft and 30-in. models of the conical-Gregorian and Quadreflex concepts respectively were sufficiently encouraging to warrant further development of the concepts.

  16. Robust multivariable controller design for flexible spacecraft

    Science.gov (United States)

    Joshi, Suresh M.; Armstrong, Ernest S.

    1986-01-01

    Large, flexible spacecraft are typically characterized by a large number of significant elastic modes with very small inherent damping, low, closely spaced natural frequencies, and the lack of accurate knowledge of the structural parameters. Summarized here is some recent research on the design of robust controllers for such spacecraft, which will maintain stability, and possible performance, despite these problems. Two types of controllers are considered, the first being the linear-quadratic-Gaussian-(LQG)-type. The second type utilizes output feedback using collocated sensors and actuators. The problem of designing robust LQG-type controllers using the frequency domain loop transfer recovery (LTR) method is considered, and the method is applied to a large antenna model. Analytical results regarding the regions of stability for LQG-type controllers in the presence of actuator nonlinearities are also presented. The results obtained for the large antenna indicate that the LQG/LTR method is a promising approach for control system design for flexible spacecraft. For the second type of controllers (collocated controllers), it is proved that the stability is maintained in the presence of certain commonly encountered nonlinearities and first-order actuator dynamics. These results indicate that collocated controllers are good candidates for robust control in situations where model errors are large.

  17. Spacecraft Charging Sensitivity to Material Properties

    Science.gov (United States)

    Minow, Joseph I.; Edwards, David L.

    2015-01-01

    Evaluating spacecraft charging behavior of a vehicle in the space environment requires knowledge of the material properties relevant to the charging process. Implementing surface and internal charging models requires a user to specify a number of material electrical properties including electrical resistivity parameters (dark and radiation induced), dielectric constant, secondary electron yields, photoemission yields, and breakdown strength in order to correctly evaluate the electric discharge threat posed by the increasing electric fields generated by the accumulating charge density. In addition, bulk material mass density and/or chemical composition must be known in order to analyze radiation shielding properties when evaluating internal charging. We will first describe the physics of spacecraft charging and show how uncertainties in material properties propagate through spacecraft charging algorithms to impact the results obtained from charging models. We then provide examples using spacecraft charging codes to demonstrate their sensitivity to material properties. The goal of this presentation is to emphasize the importance in having good information on relevant material properties in order to best characterize on orbit charging threats.

  18. CAS Experiments Onboard Spacecraft Successful

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ The descent module of China's Shenzhou 3 spacecraft returned to Earth on April 1, 2002, one week after the spacecraft was launched at the Jiuquan Satellite Launching Center in Gansu Province. It was the third test flight of a prototype spacecraft expected to carry taikonauts (stemming from the Chinese words for outer space) into space in the near future since the first launch of the Shenzhou (Divine Vessel) series on November 20,1999.

  19. Small Spacecraft Activities at JPL

    OpenAIRE

    Jones, Ross

    1991-01-01

    This paper presents a brief technical description of some of the small spacecraft concepts prepared by JPL for various sponsors. Some of JPL's work in microspacecraft is presented. The paper contains brief technical descriptions of the following four small spacecraft conceptual designs: 1) Lunar GAS, 2) Polar Mesoscale Explorer, 3) DARPA SHF and 4) Discovery. Since 1986, JPL has studied more than 10 small spacecraft including those to be presented here.

  20. Operationally Responsive Spacecraft Subsystem Project

    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...

  1. 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 (sustain a broad range of planetary environments (i.e., radiations, temperatures, limited power generation) and offer long-range telecommunication performance on a par with science needs. Other capabilities needed for planetary missions, such as fine 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.

  2. Analyzing Spacecraft Telecommunication Systems

    Science.gov (United States)

    Kordon, Mark; Hanks, David; Gladden, Roy; Wood, Eric

    2004-01-01

    Multi-Mission Telecom Analysis Tool (MMTAT) is a C-language computer program for analyzing proposed spacecraft telecommunication systems. MMTAT utilizes parameterized input and computational models that can be run on standard desktop computers to perform fast and accurate analyses of telecommunication links. MMTAT is easy to use and can easily be integrated with other software applications and run as part of almost any computational simulation. It is distributed as either a stand-alone application program with a graphical user interface or a linkable library with a well-defined set of application programming interface (API) calls. As a stand-alone program, MMTAT provides both textual and graphical output. The graphs make it possible to understand, quickly and easily, how telecommunication performance varies with variations in input parameters. A delimited text file that can be read by any spreadsheet program is generated at the end of each run. The API in the linkable-library form of MMTAT enables the user to control simulation software and to change parameters during a simulation run. Results can be retrieved either at the end of a run or by use of a function call at any time step.

  3. Combined space environment on spacecraft engineering materials

    Science.gov (United States)

    Workman, Gary L.; Smith, Guy A.; Kosten, Susan

    1993-01-01

    Spacecraft structures and surface materials exposed to the space environment for extended periods, up to thirty years, have increased potential for damage from long term exposure to the combined space environment including solar ultraviolet radiation, electrons, and protons and orbiting space debris. The space environment in which the Space Station Freedom and other space platforms will orbit is truly a hostile environment. For example, the currently estimated integral fluence for electrons above 1 Mev at 2000 nautical miles is above 2 x 10(exp 10) electrons/cm(sup 2)/day and the proton integral fluence is above 1 x 10(exp 9) protons/cm(sup 2)/day. At the 200 - 400 nautical miles, which is more representative of the altitude which will provide the environment for the Space Station, each of these fluences will be proportionately less; however, the data indicates that the radiation environment will obviously have an effect on structural materials exposed to the environment for long durations. The effects of ultraviolet radiation, particularly in the vacuum ultraviolet (less than 200 nm wavelength) is more difficult to characterize at this time. Very little data is available in the literature which can be used for determining the life cycle of a material placed in space for extended durations of time. In order to obtain critical data for planning and designing of spacecraft systems, use of a small vacuum system at the Environmental Effects Facility at MSFC, which can be used for these purposes was used. A special effort was made to build up this capability during the course of this research effort and perform a variety of experiments on materials proposed for the Space Station. A description of the apparatus and the procedure devised to process potential spacecraft materials is included.

  4. Spacecraft Cabin Particulate Monitor Project

    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...

  5. Advanced Spacecraft Thermal Modeling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For spacecraft developers who spend millions to billions of dollars per unit and require 3 to 7 years to deploy, the LoadPath reduced-order (RO) modeling thermal...

  6. Spacecraft Cabin Particulate Monitor Project

    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...

  7. Gravity Probe B spacecraft description

    Science.gov (United States)

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

    2015-11-01

    The Gravity Probe B spacecraft, developed, integrated, and tested by Lockheed Missiles & 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.

  8. Interplanetary spacecraft navigation using pulsars

    OpenAIRE

    Deng, X. P.; Hobbs, G.; You, X. P.; M. T. Li; Keith, M. J.; Shannon, R. M.; Coles, W.; Manchester, R. N.; J.H. Zheng; Yu, X. Z.; Gao, D.; Wu, X; Chen, D.

    2013-01-01

    We demonstrate how observations of pulsars can be used to help navigate a spacecraft travelling in the solar system. We make use of archival observations of millisecond pulsars from the Parkes radio telescope in order to demonstrate the effectiveness of the method and highlight issues, such as pulsar spin irregularities, which need to be accounted for. We show that observations of four millisecond pulsars every seven days using a realistic X-ray telescope on the spacecraft throughout a journe...

  9. Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems

    CERN Document Server

    Lissauer, Jack J; Fabrycky, Daniel C; Batalha, Natalie M; Borucki, William J; Bryson, Stephen T; Caldwell, Douglas A; Dunham, Edward W; Ford, Eric B; Fortney, Jonathan J; Gautier, Thomas N; Holman, Matthew J; Jenkins, Jon M; Koch, David G; Latham, David W; Marcy, Geoffrey W; Morehead, Robert; Rowe, Jason; Quintana, Elisa V; Sasselov, Dimitar; Shporer, Avi; Steffen, Jason H

    2011-01-01

    Borucki et al. 2011 (ApJ, submitted) report on characteristics of over 1200 candidate transiting planets orbiting nearly 1000 Kepler spacecraft target stars detected in the first four months of spacecraft data. Included among these targets are 115 targets with two transiting planet candidates, 45 targets with three, 8 with four, and one each with five and six sets of transit signatures. We characterize herein the dynamical properties of these candidate multi-planet systems. We find that virtually all systems are stable, as tested by numerical integration assuming a mass-radius relationship. The distribution of observed period ratios is also clustered just outside resonances, particularly the 2:1 resonance. Neither of these characteristics would emerge if the systems were significantly contaminated with false positives, and these combined with other considerations strongly suggest that the majority of these multi-candidate systems are true planetary systems. Using the observed multiplicity frequencies (e.g., t...

  10. Structural stability at high pressure, electronic, and magnetic properties of BaFZnAs: A new candidate of host material of diluted magnetic semiconductors

    Science.gov (United States)

    Bi-Juan, Chen; Zheng, Deng; Xian-Cheng, Wang; Shao-Min, Feng; Zhen, Yuan; Si-Jia, Zhang; Qing-Qing, Liu; Chang-Qing, Jin

    2016-07-01

    The layered semiconductor BaFZnAs with the tetragonal ZrCuSiAs-type structure has been successfully synthesized. Both the in-situ high-pressure synchrotron x-ray diffraction and the high-pressure Raman scattering measurements demonstrate that the structure of BaFZnAs is stable under pressure up to 17.5 GPa at room temperature. The resistivity and the magnetic susceptibility data show that BaFZnAs is a non-magnetic semiconductor. BaFZnAs is recommended as a candidate of the host material of diluted magnetic semiconductor. Project supported by the National Natural Science Foundation of China and Project of Ministry of Science and Technology of China.

  11. Limit on the Two-Photon Production of the Glueball Candidate fJ(2220) at the Cornell Electron Storage Ring

    International Nuclear Information System (INIS)

    We use the CLEO detector at the Cornell e+e- storage ring, CESR, to search for the two-photon production of the glueball candidate fJ(2220) in its decay to KsKs . We present a restrictive upper limit on the product of the two-photon partial width and the KsKs branching fraction, (ΓγγBKsKs)fJ(2220) . We use this limit to calculate a lower limit on the stickiness, which is a measure of the two-gluon coupling relative to the two-photon coupling. This limit on stickiness indicates that the fJ(2220) has substantial glueball content. copyright 1997 The American Physical Society

  12. The Space Environment Monitors of Shenzhou Manned Spacecrafts

    Institute of Scientific and Technical Information of China (English)

    XU Ying; WANG Chunqin; YE Haihua; JING Guiru; ZHU Guangwu; WANG Shijin; QIN Guotai; LIANG Jinbao; SUN Yueqiang; HUANG Xiuying; YANG Xiaochao; WANG Yue

    2004-01-01

    For the purpose of ensuring normal operations of Shenzhou (SZ) series of manned spacecrafts and cosmonauts' safety, Space Environment Monitors (SEM)are mounted on board SZ-2, 3, 4, 5. SEMs aim to detect the high energy particles, the low energy particles, charging potential, atmospheric desity and composition. Detection of SEMs enable us to understand better the space environment in the manned spacecraft's orbit, and to provide a good space environment services for the spacecraft and cosmonauts. In addition, by using the data from SEMs, we have achieved some scientific accomplishments, such as the energy spectra of precipitating electrons, the abnormal variety of atmospheric density and composition during geomagnetic disturbances, the electron angle distribution in the low orbit and so on.

  13. Solar wind plasma interaction with solar probe plus spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Guillemant, S. [Univ. Paul Sabatier de Toulouse et CNRS, Toulouse (FR). IRAP (Inst. der Recherche en Astrophysique et Planetologie); ONERA (Office National d' Etudes et Recherches Aerospatiales), Toulouse (France); Genot, V.; Louarn, P. [Univ. Paul Sabatier de Toulouse et CNRS, Toulouse (FR). IRAP (Inst. der Recherche en Astrophysique et Planetologie); Mateo-Velez, J.C. [ONERA (Office National d' Etudes et Recherches Aerospatiales), Toulouse (France); Ergun, R. [Colorado Univ., Boulder, CO (United States). Lab. for Atmospheric and Space Physics

    2012-07-01

    3-D PIC (Particle In Cell) simulations of spacecraft-plasma interactions in the solar wind context of the Solar Probe Plus mission are presented. The SPIS software is used to simulate a simplified probe in the near-Sun environment (at a distance of 0.044AU or 9.5 R{sub S} from the Sun surface).We begin this study with a cross comparison of SPIS with another PIC code, aiming at providing the static potential structure surrounding a spacecraft in a high photoelectron environment. This paper presents then a sensitivity study using generic SPIS capabilities, investigating the role of some physical phenomena and numerical models. It confirms that in the near- sun environment, the Solar Probe Plus spacecraft would rather be negatively charged, despite the high yield of photoemission. This negative potential is explained through the dense sheath of photoelectrons and secondary electrons both emitted with low energies (2-3 eV). Due to this low energy of emission, these particles are not ejected at an infinite distance of the spacecraft and would rather surround it. As involved densities of photoelectrons can reach 10{sup 6} cm{sup -3} (compared to ambient ions and electrons densities of about 7 x 10{sup 3} cm{sup -3}), those populations affect the surrounding plasma potential generating potential barriers for low energy electrons, leading to high recollection. This charging could interfere with the low energy (up to a few tens of eV) plasma sensors and particle detectors, by biasing the particle distribution functions measured by the instruments. Moreover, if the spacecraft charges to large negative potentials, the problem will be more severe as low energy electrons will not be seen at all. The importance of the modelling requirements in terms of precise prediction of spacecraft potential is also discussed. (orig.)

  14. Flight Experiments on the Effects of Contamination on Electron Emission of Materials

    OpenAIRE

    Dennison, JR; Hodges, Joshua L.; Duce, Jeff; Evans, Amberly

    2009-01-01

    We report on a study of the effects of prolonged exposure to the space environment and of chargeenhanced contamination on the electron emission and resistivity of spacecraft materials. The State of Utah Space Environment & Contamination Study (SUSpECS) was deployed on the International Space Station (ISS) in March 2008 onboard the MISSE-6 payload during STS-123. The Materials International Space Station Experiment (MISSE-6) program is designed to characterize the performance of candidate new ...

  15. Low Energy Electron Gun Power Control Unit

    OpenAIRE

    Fish, Chad

    1998-01-01

    Orbiting spacecraft are subject to surface charging induced by plasma currents. The reaction of spacecraft materials to electron and ion bombardments is a major factor in spacecraft surface charging. A key bombardment process known to induce severe spacecraft surface charging is secondary electron emission. NASA funds the Surface Science Group in the Physics Department at Utah State University to research and document different secondary electron emission material characteristics. The Surface...

  16. CMS Higgs Search in 2011 and 2012 data: candidate ZZ event (8 TeV) with two electrons and two muons

    CERN Multimedia

    McCauley, T

    2012-01-01

    Event recorded with the CMS detector in 2012 at a proton-proton centre of mass energy of 8 TeV. The event shows characteristics expected from the decay of the SM Higgs boson to a pair of Z bosons, one of which subsequently decays to a pair of electrons (green lines and green towers) and the other Z decays to a pair of muons (red lines). The event could also be due to known standard model background processes.

  17. Electromagnetic braking for Mars spacecraft

    Science.gov (United States)

    Holt, A. C.

    1986-01-01

    Aerobraking concepts are being studied to improve performance and cost effectiveness of propulsion systems for Mars landers and Mars interplanetary spacecraft. Access to megawatt power levels (nuclear power coupled to high-storage inductive or capacitive devices) on a manned Mars interplanetary spacecraft may make feasible electromagnetic braking and lift modulation techniques which were previously impractical. Using pulsed microwave and magnetic field technology, potential plasmadynamic braking and hydromagnetic lift modulation techniques have been identified. Entry corridor modulation to reduce loads and heating, to reduce vertical descent rates, and to expand horizontal and lateral landing ranges are possible benefits. In-depth studies are needed to identify specific design concepts for feasibility assessments. Standing wave/plasma sheath interaction techniques appear to be promising. The techniques may require some tailoring of spacecraft external structures and materials. In addition, rapid response guidance and control systems may require the use of structurally embedded sensors coupled to expert systems or to artificial intelligence systems.

  18. Autonomous Spacecraft Navigation With Pulsars

    CERN Document Server

    Becker, Werner; Jessner, Axel

    2013-01-01

    An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board a spacecraft with predicted pulse arrivals at a reference location, the spacecraft position can be determined autonomously and with high accuracy everywhere in the solar system and beyond. The unique properties of pulsars make clear already today that such a navigation system will have its application in future astronautics. In this paper we describe the basic principle of spacecraft navigation using pulsars and report on the current development status of this novel technology.

  19. Meteoroid Impacts on Spacecraft

    Science.gov (United States)

    Foschini, Luigi

    In the space age, information about the near-Earth environment is becoming more and more important, because of the potential danger to human exploration and use of space. In recent years there have been a number of in situ space experiments, such as LDEF and EURECA, that have demonstrated the threaths to satellites, space station, and astronauts from high-kinetic-energy impacts of meteoroids and space debris. Post-flight analyses of data from these satellites have revealed that, the catastrophic impact to be a rare event; however, the main danger comes from the impact-generated plasma, which can produce several types of electromagnetic interferences that can disturb or even destroy on-board electronics.

  20. What's the Kepler Spacecraft Been Up To?

    Science.gov (United States)

    Kohler, Susanna

    2016-03-01

    Remember back in May 2013 when the second of Keplers reaction wheels failed, rendering it unable to control its precision pointing? As a result of a clever backup plan by intrepid scientists, Kepler is still going strong! This January, a paper was published describing some of the results from the first year of the extended Kepler mission, known as K2.K2: A Second ChanceHistograms of the K2 planet candidate sample (solid yellow) compared with planet candidates from the first four months of Kepler observations (blue diagonal lines). The histograms compare planet radius, orbital period, and brightness. [Vanderburg et al. 2016]After an incredibly successful five years discovering transiting exoplanets, the failure of two of Keplers reaction wheels (which allow it to maintain its orientation) looked like it would shut down the mission. Luckily, the scientific community came up with the ingenious plan of stabilizing the telescope using the radiation pressure exerted by the Sun. Though this solution limits Kepler to observing within the ecliptic plane, it has provided a new life lease for the project.Despite the significantly worsened pointing precision in the K2 mission, new analysis techniques have been developed that decouple the motion of the spacecraft from its observations, resulting in an observational precision for K2 thats within 35% of the original precision achieved by Kepler.Using these techniques, a team of scientists led by Andrew Vanderburg (HarvardSmithsonian Center for Astrophysics) analyzed the publicly released data from the first year of the K2 mission. In a new study, they describe the results from the 59,174 targets that Kepler has observed in that time.Planetary CandidatesVanderburg and collaborators report that K2 has detected 234 planetary candidates around 208 stars in its first year. These candidates span a range of sizes from gas-giant to smaller than the Earth, and have orbital periods that range from hours to more than a month. The list

  1. Interplanetary spacecraft navigation using pulsars

    CERN Document Server

    Deng, X P; You, X P; Li, M T; Keith, M J; Shannon, R M; Coles, W; Manchester, R N; Zheng, J H; Yu, X Z; Gao, D; Wu, X; Chen, D

    2013-01-01

    We demonstrate how observations of pulsars can be used to help navigate a spacecraft travelling in the solar system. We make use of archival observations of millisecond pulsars from the Parkes radio telescope in order to demonstrate the effectiveness of the method and highlight issues, such as pulsar spin irregularities, which need to be accounted for. We show that observations of four millisecond pulsars every seven days using a realistic X-ray telescope on the spacecraft throughout a journey from Earth to Mars can lead to position determinations better than approx. 20km and velocity measurements with a precision of approx. 0.1m/s.

  2. Polyurethane Membranes Modified with Isopropyl Myristate as a Potential Candidate for Encapsulating Electronic Implants: A Study of Biocompatibility and Water Permeability

    Directory of Open Access Journals (Sweden)

    Deepen Paul

    2010-07-01

    Full Text Available Medical polyurethanes have shown good bio-stability and mechanical properties and have been used as coating for implantable medical devices. However, despite their excellent properties, they are relatively permeable to liquid water and water vapour which is a drawback for electronic implant encapsulation. In this study polyether polyurethanes with different soft segment molecular weights were modified by incorporating isopropyl myristate (IPM, as a hydrophobic modifying agent, and the effect of IPM on water resistant and biocompatibility of membranes were investigated. IPM changed the surface properties of the polyurethane film and reduced its surface energy. Polyurethane films were found to be stable with IPM concentrations of 1–5 wt% based upon their chemistry; however it leached out in BSA at higher concentrations. Though, low concentrations of IPM reduced both liquid water and water vapour permeability; at higher IPM content liquid permeability did not improved significantly. In general, the polyurethane materials showed much lower water permeability compared with currently used silicone packaging material for electronic implants. In addition, cytotoxicity assessment of IPM containing polyurethanes showed no evidence of cytotoxcity up to 5 wt% IPM.

  3. Multi-Spacecraft Observations of the Auroral Acceleration Region

    OpenAIRE

    Sadeghi, Soheil

    2012-01-01

    The two major agents for producing aurora are generally believed to be the quasi-static parallel electric fields, accelerating electrons in the auroral acceleration region (AAR), and Alfvén waves. The Cluster spacecraft quartet has made multi-spacecraft measurements in the AAR possible for the first time. Four event studies are included and discussed in this thesis, using Cluster data inside and at the top of the AAR, to address various open issues regarding the nature of the quasistatic elec...

  4. Future trends in spacecraft design and qualification

    Science.gov (United States)

    Venneri, Samuel L.; Hanks, Brantley R.; Pinson, Larry D.

    1986-01-01

    Material and structures issues that must be resolved in order to develop the technology data base needed to design and qualify the next generation of large flexible spacecraft are discussed. This invoves the development of new ground test and analysis methods and the conduct of appropriate instrumented in-space flight experiments for final verification. A review of present understanding of material behavior in the space environment and identification of future needs is presented. The dynamic verification and subsequent qualification of a spacecraft structure currently rely heavily on ground-based tests, coupled with the verified analysis model. Future space structures, such as large antennas, Space Station and other large platforms, will be of sizes difficult to test using current ground test methods. In addition to size, other complex factors, such as low natural frequencies, lightweight construction and many structural joints, will also contribute significant problems to the test and qualification process in an Earth-gravity environment. These large spacecraft will also require new technology for controlling the configuration and dynamic deformations of the structures. Future trend in large flexible structures will also involve long-life design missions (10 to 20 years). In low earth orbit (LEO), materials will be subjected to repeated thermal cycles, ultraviolet radiation, atomic oxygen and vacuum. For high orbits such as geo-synchronous earth orbit (GEO), the materials will also be subjected to large doses of high energy electrons and protons. Understanding degradation and material stability over long-mission time periods will confront the designer with many issues that are unresolved today.

  5. Spacecraft Maximum Allowable Concentrations for Airborne Contaminants

    Science.gov (United States)

    James, John T.

    2008-01-01

    The enclosed table lists official spacecraft maximum allowable concentrations (SMACs), which are guideline values set by the NASA/JSC Toxicology Group in cooperation with the National Research Council Committee on Toxicology (NRCCOT). These values should not be used for situations other than human space flight without careful consideration of the criteria used to set each value. The SMACs take into account a number of unique factors such as the effect of space-flight stress on human physiology, the uniform good health of the astronauts, and the absence of pregnant or very young individuals. Documentation of the values is given in a 5 volume series of books entitled "Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants" published by the National Academy Press, Washington, D.C. These books can be viewed electronically at http://books.nap.edu/openbook.php?record_id=9786&page=3. Short-term (1 and 24 hour) SMACs are set to manage accidental releases aboard a spacecraft and permit risk of minor, reversible effects such as mild mucosal irritation. In contrast, the long-term SMACs are set to fully protect healthy crewmembers from adverse effects resulting from continuous exposure to specific air pollutants for up to 1000 days. Crewmembers with allergies or unusual sensitivity to trace pollutants may not be afforded complete protection, even when long-term SMACs are not exceeded. Crewmember exposures involve a mixture of contaminants, each at a specific concentration (C(sub n)). These contaminants could interact to elicit symptoms of toxicity even though individual contaminants do not exceed their respective SMACs. The air quality is considered acceptable when the toxicity index (T(sub grp)) for each toxicological group of compounds is less than 1, where T(sub grp), is calculated as follows: T(sub grp) = C(sub 1)/SMAC(sub 1) + C(sub 2/SMAC(sub 2) + ...+C(sub n)/SMAC(sub n).

  6. Propulsion Challenges for Small Spacecraft: 2005

    Institute of Scientific and Technical Information of China (English)

    Vadim Zakirov; LI Luming

    2006-01-01

    Small (<100 kg) spacecrafts are being developed in many countries but their propulsion systems still have many challenges. Although there is demand for small spacecraft propulsion, the number of missions at present is small due to several commercial and technical reasons. Poor performance of existing small spacecraft propulsion systems is one of the main reasons for the small number of missions. Several reasons are given for the poor performance of existing small spacecraft propulsion. Suggested improvements focus on small spacecraft and propulsion hardware mass optimization rather than on specific impulse enhancement. Propellantless propulsion systems are also recommended for small spacecraft interplanetary missions.

  7. Optimal Reorientation Of Spacecraft Orbit

    Directory of Open Access Journals (Sweden)

    Chelnokov Yuriy Nikolaevich

    2014-06-01

    Full Text Available The problem of optimal reorientation of the spacecraft orbit is considered. For solving the problem we used quaternion equations of motion written in rotating coordinate system. The use of quaternion variables makes this consideration more efficient. The problem of optimal control is solved on the basis of the maximum principle. An example of numerical solution of the problem is given.

  8. Software Architecture for Autonomous Spacecraft

    Science.gov (United States)

    Shih, Jimmy S.

    1997-01-01

    The thesis objective is to design an autonomous spacecraft architecture to perform both deliberative and reactive behaviors. The Autonomous Small Planet In-Situ Reaction to Events (ASPIRE) project uses the architecture to integrate several autonomous technologies for a comet orbiter mission.

  9. Performance of candidate SEPS solar cells as a function of low temperature and low intensity exposure and 1 MeV electron irradiation

    Science.gov (United States)

    Whitaker, A. F.; Little, S. A.; Rives, C. J.; Wagner, P. E.

    1981-01-01

    The behavior of 144 high-performance shallow-junction silicon solar cells under conditions of low temperature and intensity was examined. The cells represented nine combinations of thickness, base resistivity, front surface texture, and rear surface treatment. At least 16 cells of each type were individually tested both as active elements under light levels between 0.04 and 1.0 solar constant and in the dark as passive rectifiers under external forward bias. One cell type was also irradiated with 1 MeV electrons up to 2.7 x 10 to the 15th e/sq cm. The inferior cells demonstrated high ohmic and/or non-ohmic shunting. No series resistance or Schottky barrier effects were observed. Fluences beyond 10 to the 13th e/sq cm lowered cell current, probably by increasing volume recombination.

  10. Performance of candidate SEPS solar cells as a function of low temperature and low intensity exposure and 1 MeV electron irradiation

    Science.gov (United States)

    Whitaker, A. F.; Little, S. A.; Rives, C. J.; Wagner, P. E.

    1981-04-01

    The behavior of 144 high-performance shallow-junction silicon solar cells under conditions of low temperature and intensity was examined. The cells represented nine combinations of thickness, base resistivity, front surface texture, and rear surface treatment. At least 16 cells of each type were individually tested both as active elements under light levels between 0.04 and 1.0 solar constant and in the dark as passive rectifiers under external forward bias. One cell type was also irradiated with 1 MeV electrons up to 2.7 x 10 to the 15th e/sq cm. The inferior cells demonstrated high ohmic and/or non-ohmic shunting. No series resistance or Schottky barrier effects were observed. Fluences beyond 10 to the 13th e/sq cm lowered cell current, probably by increasing volume recombination.

  11. 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.

  12. Processing Images of Craters for Spacecraft Navigation

    Science.gov (United States)

    Cheng, Yang; Johnson, Andrew E.; Matthies, Larry H.

    2009-01-01

    A crater-detection algorithm has been conceived to enable automation of what, heretofore, have been manual processes for utilizing images of craters on a celestial body as landmarks for navigating a spacecraft flying near or landing on that body. The images are acquired by an electronic camera aboard the spacecraft, then digitized, then processed by the algorithm, which consists mainly of the following steps: 1. Edges in an image detected and placed in a database. 2. Crater rim edges are selected from the edge database. 3. Edges that belong to the same crater are grouped together. 4. An ellipse is fitted to each group of crater edges. 5. Ellipses are refined directly in the image domain to reduce errors introduced in the detection of edges and fitting of ellipses. 6. The quality of each detected crater is evaluated. It is planned to utilize this algorithm as the basis of a computer program for automated, real-time, onboard processing of crater-image data. Experimental studies have led to the conclusion that this algorithm is capable of a detection rate >93 percent, a false-alarm rate <5 percent, a geometric error <0.5 pixel, and a position error <0.3 pixel.

  13. Modeling of DC spacecraft power systems

    Science.gov (United States)

    Berry, F. C.

    1995-07-01

    Future spacecraft power systems must be capable of supplying power to various loads. This delivery of power may necessitate the use of high-voltage, high-power dc distribution systems to transmit power from the source to the loads. Using state-of-the-art power conditioning electronics such as dc-dc converters, complex series and parallel configurations may be required at the interface between the source and the distribution system and between the loads and the distribution system. This research will use state-variables to model and simulate a dc spacecraft power system. Each component of the dc power system will be treated as a multiport network, and a state model will be written with the port voltages as the inputs. The state model of a component will be solved independently from the other components using its state transition matrix. A state-space averaging method is developed first in general for any dc-dc switching converter, and then demonstrated in detail for the particular case of the boost power stage. General equations for both steady-state (dc) and dynamic effects (ac) are obtained, from which important transfer functions are derived and applied to a special case of the boost power stage.

  14. Multi-spacecraft Observations of the Martian Plasma Interaction

    Science.gov (United States)

    Brain, David; Luhmann, J.; Halekas, J.; Frahm, R.; Winningham, J.; Barabash, S.

    2006-09-01

    Two spacecraft with complementary instrumentation and orbits are currently making in situ measurements of the Martian plasma environment. Mars Global Surveyor (MGS) measures electrons and magnetic field from a 400 km circular mapping orbit with fixed local time. Mars Express (MEX) measures ions, electrons, and neutral particles from a precessing elliptical orbit. Each spacecraft's dataset has obvious strengths and shortcomings. Exploration of these two datasets in tandem provides an opportunity to increase our overall understanding of the Martian solar wind interaction and atmospheric escape. Close passes of spacecraft (conjunctions) are one particularly powerful means of increasing the utility of measurements, as evidenced by the Cluster mission. At Mars, conjunctions might be used to obtain more complete simultaneous and/or co-located plasma measurements, which can be used to study a variety of phenomena ranging from the motion and 3D shape of plasma boundaries to particle acceleration near crustal magnetic fields. We have identified 40 conjunctions (instances with spacecraft separation pass was 40 km. Conjunctions occur at mid-latitudes (when the surface-projected orbit tracks of the two spacecraft nearly overlap), and at the poles. We will present comparisons of MGS Magnetometer and Electron Reflectometer (MAG/ER) and MEX Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) data for these events, including intercomparison of MGS and MEX electron data, the addition of MGS magnetic field and MES ion data, and the inclusion of solar wind proxy information to establish context. Finally, we will present the results of a search for other useful configurations of MGS and MEX, including times when they are on the same flux tube, times when they pass through the same region of space separated by a delay, and times when they are on opposite sides of plasma boundaries.

  15. Fermi arc electronic structure and Chern numbers in the type-II Weyl semimetal candidate MoxW1 -xTe2

    Science.gov (United States)

    Belopolski, Ilya; Xu, Su-Yang; Ishida, Yukiaki; Pan, Xingchen; Yu, Peng; Sanchez, Daniel S.; Zheng, Hao; Neupane, Madhab; Alidoust, Nasser; Chang, Guoqing; Chang, Tay-Rong; Wu, Yun; Bian, Guang; Huang, Shin-Ming; Lee, Chi-Cheng; Mou, Daixiang; Huang, Lunan; Song, You; Wang, Baigeng; Wang, Guanghou; Yeh, Yao-Wen; Yao, Nan; Rault, Julien E.; Le Fèvre, Patrick; Bertran, François; Jeng, Horng-Tay; Kondo, Takeshi; Kaminski, Adam; Lin, Hsin; Liu, Zheng; Song, Fengqi; Shin, Shik; Hasan, M. Zahid

    2016-08-01

    It has recently been proposed that electronic band structures in crystals can give rise to a previously overlooked type of Weyl fermion, which violates Lorentz invariance and, consequently, is forbidden in particle physics. It was further predicted that MoxW1 -xTe2 may realize such a type-II Weyl fermion. Here, we first show theoretically that it is crucial to access the band structure above the Fermi level ɛF to show a Weyl semimetal in MoxW1 -xTe2 . Then, we study MoxW1 -xTe2 by pump-probe ARPES and we directly access the band structure >0.2 eV above ɛF in experiment. By comparing our results with ab initio calculations, we conclude that we directly observe the surface state containing the topological Fermi arc. We propose that a future study of MoxW1 -xTe2 by pump-probe ARPES may directly pinpoint the Fermi arc. Our work sets the stage for the experimental discovery of the first type-II Weyl semimetal in MoxW1 -xTe2 .

  16. Service Oriented Spacecraft Modeling Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The I-Logix team proposes development of the Service Oriented Spacecraft Modeling Environment (SOSME) to allow faster and more effective spacecraft system design...

  17. Quick Spacecraft Thermal Analysis Tool Project

    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...

  18. 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

  19. Attitude Fusion Techniques for Spacecraft

    DEFF Research Database (Denmark)

    Bjarnø, Jonas Bækby

    . With both sensor types providing measurements of the spacecraft attitude in space, harnessing the extreme accuracy of the μASC throughout the low frequency range and the inherent fidelity of miniature accelerometers in the high frequency domain allows the combined instrument to provide unsurpassed accuracy...... due to the extreme performance that must be ascertained on all fronts whilst harnessing only a minimum of resources. Considering the physical limitations imposed by the μASC instrument as well as the next generation of smaller and more agile satellites, the main design drivers of the IRU......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...

  20. Multi-spacecraft observations of the 2010 Jan 17 SEP event

    Science.gov (United States)

    Dresing, N.; Gómez-Herrero, R.; Klassen, A.; Heber, B.; Kartavykh, Y.; Droege, W.

    2010-12-01

    During the rising phase of solar cycle 24 several solar energetic particle (SEP) events have been observed by three well separated viewpoints provided by the STEREO and SOHO spacecraft. The longitudinal separation of > 130 degrees of the two STEREO spacecraft in Jan 2010 offers a unique possibility to investigate the angular distribution of SEPs at 1 AU. In this work we present multi-spacecraft observations of the Jan 17, 2010 SEP event, whose associated flare and EIT wave were only seen at the southern East limb by STEREO B and remained behind the limb for STEREO A and SOHO. Energetic electron increases were measured by the Solar Electron Proton Telescopes (SEPT) onboard both STEREO spacecraft and the Electron Proton Helium Instrument (EPHIN) on SOHO. The longitudinal separation between the active region and the nominal magnetic footpoint of the spacecraft varies between 108 degeees for STEREO B and 170 degrees for SOHO.The associated radio type III burst was observed at 3:56 UT on day 17, 2010. The electron onset time at all three spacecraft was delayed by more than one hour. Although the electrons started to rise 20 minutes later at STEREO A than at STEREO B, the intensity was a factor of about 7 higher at STEREO A. We tentatively suggest that an EIT wave observed by STEREO B , which was heading towards the magnetic footpoint of STEREO B, plays a crucial role for the electron release.

  1. Energy Storage Flywheels on Spacecraft

    Science.gov (United States)

    Bartlett, Robert O.; Brown, Gary; Levinthal, Joel; Brodeur, Stephen (Technical Monitor)

    2002-01-01

    With advances in carbon composite material, magnetic bearings, microprocessors, and high-speed power switching devices, work has begun on a space qualifiable Energy Momentum Wheel (EMW). An EMW is a device that can be used on a satellite to store energy, like a chemical battery, and manage angular momentum, like a reaction wheel. These combined functions are achieved by the simultaneous and balanced operation of two or more energy storage flywheels. An energy storage flywheel typically consists of a carbon composite rotor driven by a brushless DC motor/generator. Each rotor has a relatively large angular moment of inertia and is suspended on magnetic bearings to minimize energy loss. The use of flywheel batteries on spacecraft will increase system efficiencies (mass and power), while reducing design-production time and life-cycle cost. This paper will present a discussion of flywheel battery design considerations and a simulation of spacecraft system performance utilizing four flywheel batteries to combine energy storage and momentum management for a typical LEO satellite. A proposed set of control laws and an engineering animation will also be presented. Once flight qualified and demonstrated, space flywheel batteries may alter the architecture of most medium and high-powered spacecraft.

  2. Cross-field gradients: general concept, importance of multi-spacecraft measurements and study at 1 AU of the source intensity gradient for E > 30 keV solar event electrons

    Directory of Open Access Journals (Sweden)

    P. A. Chaizy

    Full Text Available Three main physical processes (and associated properties are currently used to describe the flux and anisotropy time profiles of solar energetic par- ticle events, called SEP profiles. They are (1 the particle scattering (due to magnetic waves, (2 the particle focusing (due to the decrease of the amplitude of the interplanetary magnetic field (IMF with the radial distance to the Sun and (3 the finite injection profile at the source. If their features change from one field line to another, i.e. if there is a cross IMF gradient (CFG, then the shape of the SEP profiles will depend, at onset time, on the relative position of the spacecraft to the IMF and might vary significantly on small distance scale (e.g. 106 km. One type of CFG is studied here. It is called intensity CFG and considers variations, at the solar surface, only of the intensity of the event. It is shown here that drops of about two orders of magnitude over distances of ~104 km at the Sun (1° of angular distance can influence dramatically the SEP profiles at 1 AU. This CFG can lead to either an under or overestimation of both the parallel mean free path and of the injection parameters by factor up to, at least, ~2-3 and 18, respectively. Multi-spacecraft analysis can be used to identify CFG. Three basic requirements are proposed to identify, from the observation, the type of the CFG being measured.

    Key words: Solar physics, astrophysics, and astronomy (energetic particles; flares and mass ejections - Space plasma physics (transport processes

  3. Electrons

    International Nuclear Information System (INIS)

    Fast electrons are used to produce isotopes for studying the cooper metabolism: Cu-64 in a cyclotron and Cu-67 in a linear accelerator. Localized electrons are responsible for the chemical and physiological characteristics of the trace elements. Studied are I, Cu, Co, Zn, Mo, Mn, Fe, Se, Mg. The Cu/Mo and Cu/Zn interactions are investigated. The levels of molybdenum, sulfate and zinc in the food are analysed. The role of the electrons in free radicals is discussed. The protection action of peroxidases and super oxidases against electron dangerous effect on normal physiology is also considered. Calculation of radiation damage and radiation protection is made. (author)

  4. Spacecraft

    Science.gov (United States)

    Clark, John F.; Haggerty, James J.; Woodburn, John H.

    1961-01-01

    In this twentieth century, we are privileged to witness the first steps toward realization of an age-old dream: the exploration of space. Already, in the first few years of the Space Age, man has been able to penetrate the layer of atmosphere which surrounds his planet and to venture briefly into space. Scores of man-made objects have been thrust into space, some of them to roam the solar system forever. Behind each space mission are years of patient research, thousands of man-hours of labor, and large sums of money. Because the sums involved are so enormous, the question is frequently asked, "Is it worth it?" Many people want to know what return this huge investment will bring to mankind. The return on the investment is knowledge. The accumulation of knowledge over the centuries has made possible our advanced way of life. As we unlock more and more of the secrets of the universe through space exploration, we add new volumes to the encyclopedia of man's knowledge. This will be applied to the benefit of mankind. For the practical-minded, there are concrete benefits to our way of life. Although we are still in the Stone Age of space exploration, a number of immediate applications of space technology are already apparent. For instance, imagine the benefits of an absolutely perfect system of predicting the weather. Or, going a step further, even changing the weather. And wouldn't it be fascinating to watch the next Olympic games, telecast from Tokyo, on your TV set? These are just a few of the practical benefits made possible by space technology.

  5. Active spacecraft potential control for Cluster – implementation and first results

    Directory of Open Access Journals (Sweden)

    K. Torkar

    Full Text Available Electrostatic charging of a spacecraft modifies the distribution of electrons and ions before the particles enter the sensors mounted on the spacecraft body. The floating potential of magnetospheric satellites in sunlight very often reaches several tens of volts, making measurements of the cold (several eV component of the ambient ions impossible. The plasma electron data become contaminated by large fluxes of photoelectrons attracted back into the sensors. The Cluster spacecraft are equipped with emitters of the liquid metal ion source type, producing indium ions at 5 to 9 keV energy at currents of some tens of microampere. This current shifts the equilibrium potential of the spacecraft to moderately positive values. The design and principles of the operation of the instrument for active spacecraft potential control (ASPOC are presented in detail. Experience with spacecraft potential control from the commissioning phase and the first two months of the operational phase are now available. The instrument is operated with constant ion current for most of the time, but tests have been carried out with varying currents and a "feedback" mode with the instrument EFW, which measures the spacecraft potential . That has been reduced to values according to expectations. In addition, the low energy electron measurements show substantially reduced fluxes of photoelectrons as expected. The flux decrease in photoelectrons returning to the spacecraft, however, occurs at the expense of an enlarged sheath around the spacecraft which causes problems for boom-mounted probes.

    Key words. Space plasma physics (spacecraft sheaths, wakes, charging; Instruments and techniques; Active perturbation experiments

  6. Maneuver analysis for spinning thrusting spacecraft and spinning tethered spacecraft

    Science.gov (United States)

    Martin, Kaela M.

    During axial thrusting of a spin-stabilized spacecraft undergoing orbital injections or control maneuvers, misalignments and center-of-mass offset create undesired body-fixed torques. The effects of the body-fixed torques, which in turn cause velocity pointing errors, can be reduced by ramping up (and then ramping down) the thruster. The first topic discussed in this thesis derives closed-form solutions for the angular velocity, Euler angles, inertial velocity, and inertial displacement solutions with nonzero initial conditions. Using the closed-form solutions, the effect of variations in the spin-axis moment of inertia and spin-rate on the spacecraft velocity pointing error are shown. The analytical solutions closely match numerical simulations. The next topic considers various ramp-up profiles (including parabolic, cosine, logarithmic, exponential, and cubic) to heuristically find a suboptimal solution to reduce the velocity pointing error. Some of the considered cosine, logarithmic, exponential, parabolic, and cubic profiles drive the velocity pointing error to nearly zero and hence qualify as effective solutions. The third topic examines a large tethered spacecraft that produces artificial gravity with the propulsion system on one end of the tether. Instead of thrusting through the center of mass, the offset thrust occurs at an angle to the tether which is held in the desired direction by changing the spin rate to compensate for decreasing propellant mass. The dynamics and control laws of the system are derived for constant, time-varying, planar, and non-planar thrust as well as spin-up maneuvers. The final topic discusses how the Bodewadt solution of a self-excited rigid body is unable to accurately predict the motion compared to a numerical integration of the equations of motion.

  7. CASE via MS: Ranking Structure Candidates by Mass Spectra

    OpenAIRE

    Kerber, Adalbert; Meringer, Markus; Rücker, Christoph

    2006-01-01

    Two important tasks in computer-aided structure elucidation (CASE) are the generation of candidate structures from a given molecular formula, and the ranking of structure candidates according to compatibility with an experimental spectrum. Candidate ranking with respect to electron impact mass spectra is based on virtual fragmentation of a candidate structure and comparison of the fragments’ isotope distributions against the spectrum of the unknown compound, whence a structure–spectrum compat...

  8. Advanced antennas for SAR spacecraft

    Science.gov (United States)

    Gail, William B.

    1993-01-01

    Single and multi-frequency antenna concepts were developed to evaluate the feasibility of building large aperture polarimetric synthetic aperture radar (SAR) systems to be launched in low cost vehicles such as the Delta 2. The antennas are 18.9 m long by 2.6 m wide (L-band) and achieve single polarization imaging to an incidence angle of 55 degrees and dual/quad imaging to 42 degrees. When combined with strawman spacecraft designs, both concepts meet the mass and volume constraints imposed by a Delta 2 launch.

  9. Teaching "Candide": A Debate.

    Science.gov (United States)

    Braun, Theodore E. D.; And Others

    1988-01-01

    Two different approaches to teaching Voltaire's "Candide", one deriving meaning from the textual fabric or "inside" of the story and the other focusing on the author's "external" intent in writing the story, are presented and compared. (MSE)

  10. Two spacecraft measurements of the Martian plasma environment

    Science.gov (United States)

    Brain, David; Luhmann, Janet G.; Barabash, Stas; Fedorov, A.; Winningham, D. L.; Acuna, Mario; Frahm, Rudy

    For a period of nearly three years from early 2004 through late 2006, two spacecraft made complementary in situ measurements of the Martian plasma environment. The Mars Global Surveyor magnetometer and electron reflectometer (MGS MAG/ER) measured magnetic fields and suprathermal electrons from an orbit fixed in local time and altitude. The Mars Express Analyzer of Space Plasma and Energetic Atoms (MEX ASPERA-3) measured and still measures ions and suprathermal electrons from a precessing elliptical orbit. MGS lacked an ion instrument, and MEX lacks a magnetometer. Study of the two sets of measurements together provides an opportunity to better understand the complete Martian plasma environment spatially and temporally. We will discuss several advantageous configurations of MEX and MGS, and present examples of each. 'Close conjunctions' are defined as periods when the spacecraft passed very close to each other, within an ion gyroradius or inertial length, allowing examination of more complete particle and field measurements in a given region. 'Delay conjunctions' are defined as instances when the two spacecraft passed through the same region of space separated by a time delay, allowing examination of the evolution of electron distributions in a given region. 'Flux tube conjunctions' are defined as instances when it was likely that the two spacecraft occupied the same flux tube some distance apart, allowing study of the spatial evolution of plasma as it moves along a flux tube. We will also present examples of other fortuitous configurations of MEX and MGS, such as times when they were on opposite sides of a given plasma boundary.

  11. First Spacecraft Orbit of Mercury

    Science.gov (United States)

    Showstack, Randy

    2011-03-01

    After a 7.9-billion-kilometer flight since its launch on 3 August 2004—which included flybys of Earth, Venus, and Mercury—NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered a planned, highly elliptical orbit around the closest planet to our Sun on 17 March. Engineers in the mission operations center at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) in Laurel, Md., which manages the mission for NASA, received radiometric signals indicating a successful orbit insertion at 9:10 P.M. local time. "Tonight we will have orbited the fifth planet in the solar system. This is a major accomplishment," Ed Weiler, NASA assistant administrator for the Science Mission Directorate, said at a 17 March public forum at JHU/APL, noting that spacecraft have previously entered orbit around several other planets. "You only go into orbit for the first time around Mercury once in human history, and that is what was accomplished tonight."

  12. 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.

  13. Analysis of surface charging for a candidate solar sail mission using Nascap-2k

    OpenAIRE

    Parker, L. F. Neergaard; Minow, J. I.; Davis, V. A.; Mandell, M. J.; Gardner, B M

    2005-01-01

    The characterization of the electromagnetic interaction for a solar sail in the solar wind environment and identification of viable charging mitigation strategies are critical solar sail mission design tasks. Spacecraft charging has important implications both for science applications and for lifetime and reliability issues of sail propulsion systems. To that end, surface charging calculations of a candidate 150-meter-class solar sail spacecraft for the 0.5 AU solar polar and 1.0 AU L1 solar ...

  14. A spacecraft for the Earth observing system

    Science.gov (United States)

    Taylor, Raynor L.; Bordi, Francesco

    1995-04-01

    The space segment of NASA's Earth observing system (EOS) includes three series of intermediate-sized spacecraft, plus two smaller spacecraft. The EOS-AM spacecraft is the first of the intermediate-sized spacecraft. EOS-AM accommodates sensors that measure cloud and aerosol radiative properties, and that provide data to study the water and energy cycles. Scheduled for launch in the late 1990s, the EOS-AM spacecraft is designed for a 5-year mission. The spacecraft will be launched from the Western Space and Missile Center (California) into a polar, Sun-synchronous, low-Earth orbit with a 16-day repeat cycle. In its flight configuration, the spacecraft is almost 20 ft long (including instruments mounted at the fore end of the spacecraft) and 6 ft wide (in its widest dimension), has a mass of about 13,000 Ibs and uses about 3000 W of electrical power. The spacecraft is compatible with the Atlas IIAS launch vehicle. EOS-AM has on-board storage for at least two orbits of science data. These data will be transmitted to the ground via the tracking and data relay satellite system (using data structures and protocols in compliance with the recommendations of the Consultative Committee for Space Data Systems). A direct downlink system to support distributed users will also be available.

  15. Formation Flying Spacecraft Concept for Heliophysics Applications

    Science.gov (United States)

    Novo-Gradac, Anne-Marie; Davila, Joseph; Yang, Guangning; Lu, Wei; Shah, Neerav; Li, Steven X.

    2016-05-01

    A number of space-based heliophysics instruments would benefit from formation flying spacecraft. An occulter or a focusing optic such as a photon sieve could be mounted on a separate spacecraft rather than at the end of a boom. This would enable science measurements to be made on smaller, less expensive spacecraft. To accomplish this goal, the relative position of the spacecraft must be monitored and controlled to high precision. We describe two separate optical sensing systems that monitor relative position of the spacecraft to the level required for a photon sieve mission concept wherein the photon sieve is mounted on one spacecraft while the imaging detector is mounted on another. The first system employs a novel time of flight measurement of a laser beam that includes imbedded optical data packets. The contents of the returning data packet can be compared to the departing data packet to provide an extremely high resolution distance measurement. Employing three such systems allows measurement of pitch and yaw in addition to longitudinal separation. The second optical system monitors lateral motion. A mildy divergent laser beam is transmitted from one spacecraft to a sensor array on the second spacecraft. Monitoring the position of the brightest portion of the beam on the sensor array provides a direct measurement of lateral relative motion. Employing at least two such systems enables monitoring roll of the spacecraft as well as centration. We will also discuss low force thruster systems required for high precision station keeping.

  16. Electronics Modernization Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Current electronic packaging designs used in our most recent spacecraft are comprised of technologies from the 1980’s and 1990’s. The current approach...

  17. MarcoPolo-R: Mission and Spacecraft Design

    Science.gov (United States)

    Peacocke, L.; Kemble, S.; Chapuy, M.; Scheer, H.

    2013-09-01

    The MarcoPolo-R mission is a candidate for the European Space Agency's medium-class Cosmic Vision programme, with the aim to obtain a 100 g sample of asteroid surface material and return it safely to the Earth. Astrium is one of two industrial contractors currently studying the mission to Phase A level, and the team has been working on the mission and spacecraft design since January 2012. Asteroids are some of the most primitive bodies in our solar system and are key to understanding the formation of the Earth, Sun and other planetary bodies. A returned sample would allow extensive analyses in the large laboratory-sized instruments here on Earth that are not possible with in-situ instruments. This analysis would also increase our understanding of the composition and structure of asteroids, and aid in plans for asteroid deflection techniques. In addition, the mission would be a valuable precursor for missions such as Mars Sample Return, demonstrating a high speed Earth re-entry and hard landing of an entry capsule. Following extensive mission analysis of both the baseline asteroid target 1996 FG3 and alternatives, a particularly favourable trajectory was found to the asteroid 2008 EV5 resulting in a mission duration of 4.5 to 6 years. In October 2012, the MarcoPolo-R baseline target was changed to 2008 EV5 due to its extremely primitive nature, which may pre-date the Sun. This change has a number of advantages: reduced DeltaV requirements, an orbit with a more benign thermal environment, reduced communications distances, and a reduced complexity propulsion system - all of which simplify the spacecraft design significantly. The single spacecraft would launch between 2022 and 2024 on a Soyuz-Fregat launch vehicle from Kourou. Solar electric propulsion is necessary for the outward and return transfers due to the DeltaV requirements, to minimise propellant mass. Once rendezvous with the asteroid is achieved, an observation campaign will begin to characterise the

  18. PASS spacecraft antenna technology assessment

    Science.gov (United States)

    Freeland, R. E.

    1990-09-01

    The purpose was to generate estimates of mechanical performance for the classes of spacecraft antenna under construction for application to the Personal Access Satellite System (PASS). These performance data are needed for the support of trade studies involving antenna system development. The classes of antenna considered included: (1) rigid non-deployable antenna structures; (2) mechanical deployable antenna concepts; (3) inflatable deployable antenna concepts; and (4) mesh deployable antenna concepts. The estimates of mechanical performance are presented in terms of structural weight and cost as a function of the reflector size. Estimates of aperture surface precision are presented for a few discrete antenna sizes. The range of reflector size is 1 to 4 meters for non-deployable structures and 2 to 8 meters for deployable structures. The range of reflector surface precision is lambda/30 to lambda/50 for 20 and 30 GHz, respectively.

  19. Operator Performance Evaluation of Fault Management Interfaces for Next-Generation Spacecraft

    Science.gov (United States)

    Hayashi, Miwa; Ravinder, Ujwala; Beutter, Brent; McCann, Robert S.; Spirkovska, Lilly; Renema, Fritz

    2008-01-01

    In the cockpit of the NASA's next generation of spacecraft, most of vehicle commanding will be carried out via electronic interfaces instead of hard cockpit switches. Checklists will be also displayed and completed on electronic procedure viewers rather than from paper. Transitioning to electronic cockpit interfaces opens up opportunities for more automated assistance, including automated root-cause diagnosis capability. The paper reports an empirical study evaluating two potential concepts for fault management interfaces incorporating two different levels of automation. The operator performance benefits produced by automation were assessed. Also, some design recommendations for spacecraft fault management interfaces are discussed.

  20. 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

  1. Wet oxidation of a spacecraft model waste

    Science.gov (United States)

    Johnson, C. C.; Wydeven, T.

    1985-01-01

    Wet oxidation was used to oxidize a spacecraft model waste under different oxidation conditions. The variables studied were pressure, temperature, duration of oxidation, and the use of one homogeneous and three heterogeneous catalysts. Emphasis is placed on the final oxidation state of carbon and nitrogen since these are the two major components of the spacecraft model waste and two important plant nutrients.

  2. Embedded Spacecraft Thermal Control Using Ultrasonic Consolidation

    OpenAIRE

    Clements, Jared W.

    2009-01-01

    Research has been completed in order to rapidly manufacture spacecraft thermal control technologies embedded in spacecraft structural panels using ultrasonic consolidation. This rapid manufacturing process enables custom thermal control designs in the time frame necessary for responsive space. Successfully embedded components include temperature sensors, heaters, wire harnessing, pre-manufactured heat pipes, and custom integral heat pipes. High conductivity inserts and custom integral pulsat...

  3. Primary and Presidential Candidates

    DEFF Research Database (Denmark)

    Goddard, Joseph

    2012-01-01

    This article looks at primary and presidential candidates in 2008 and 2012. Evidence suggests that voters are less influenced by candidates’ color, gender, or religious observation than previously. Conversely, markers of difference remain salient in the imaginations of pollsters and journalists...

  4. Materials and processes for spacecraft and high reliability applications

    CERN Document Server

    D Dunn, Barrie

    2016-01-01

    The objective of this book is to assist scientists and engineers select the ideal material or manufacturing process for particular applications; these could cover a wide range of fields, from light-weight structures to electronic hardware. The book will help in problem solving as it also presents more than 100 case studies and failure investigations from the space sector that can, by analogy, be applied to other industries. Difficult-to-find material data is included for reference. The sciences of metallic (primarily) and organic materials presented throughout the book demonstrate how they can be applied as an integral part of spacecraft product assurance schemes, which involve quality, material and processes evaluations, and the selection of mechanical and component parts. In this successor edition, which has been revised and updated, engineering problems associated with critical spacecraft hardware and the space environment are highlighted by over 500 illustrations including micrographs and fractographs. Sp...

  5. Synthesis and Validation of Vision Based Spacecraft Navigation

    DEFF Research Database (Denmark)

    Massaro, Alessandro Salvatore

    to verify algorithms for asteroid detection, installed on the Juno spacecraft on its way to Jupiter. Another important outcome of the R&D effort of this project has been the integration of a calibration and validation facility for the vision based sensors developed at DTU Space. The author's work has...... at the NASA Ames Research Center's Intelligent Robotics Group (ARCIRG) resulted in the successful implementation of an infrastructure-free global localization algorithm for surface robotic navigation. The algorithm is now integrated with other rover navigation routines developed by IRG. Finally, collaboration......This dissertation targets spacecraft navigation by means of vision based sensors. The goal is to achieve autonomous, robust and ecient navigation through a multidisciplinary research and development effort, covering the fields of computer vision, electronics, optics and mechanics. The attention...

  6. The heterogeneous anti-radiation shield for spacecraft*

    Science.gov (United States)

    Telegin, S. V.; Draganyuk, O. N.

    2016-04-01

    The paper deals with modeling of elemental composition and properties of heterogeneous layers in multilayered shields to protect spacecraft onboard equipment from radiation emitted by the natural Earth’s radiation belt. This radiation causes malfunctioning of semiconductor elements in electronic equipment and may result in a failure of the spacecraft as a whole. We consider four different shield designs and compare them to the most conventional radiation-protective material for spacecraft - aluminum. Out of light and heavy chemical elements we chose the materials with high reaction cross sections and low density. The mass attenuation coefficient of boron- containing compounds is 20% higher than that of aluminum. Heterogeneous shields consist of three layers: a glass cloth, borated material, and nickel. With a protective shield containing heavy metal the output bremsstrahlung can be reduced. The amount of gamma rays that succeed to penetrate the shield is 4 times less compared to aluminum. The shields under study have the thicknesses of 5.95 and 6.2 mm. A comparative analysis of homogeneous and multilayered protective coatings of the same chemical composition has been performed. A heterogeneous protective shield has been found to be advantageous in weight and shielding properties over its homogeneous counterparts and aluminum. The dose characteristics and transmittance were calculated by the Monte Carlo method. The results of our study lead us to conclude that a three-layer boron carbide shield provides the most effective protection from radiation. This shield ensures twice as low absorbed dose and 4 times less the number of penetrated gamma-ray photons compared to its aluminum analogue. Moreover, a heterogeneous shield will have a weight 10% lighter than aluminum, with the same attenuation coefficient of the electron flux. Such heterogeneous shields can be used to protect spacecraft launched to geostationary orbit. Furthermore, a protective boron-containing and

  7. TTEthernet for Integrated Spacecraft Networks

    Science.gov (United States)

    Loveless, Andrew

    2015-01-01

    Aerospace projects have traditionally employed federated avionics architectures, in which each computer system is designed to perform one specific function (e.g. navigation). There are obvious downsides to this approach, including excessive weight (from so much computing hardware), and inefficient processor utilization (since modern processors are capable of performing multiple tasks). There has therefore been a push for integrated modular avionics (IMA), in which common computing platforms can be leveraged for different purposes. This consolidation of multiple vehicle functions to shared computing platforms can significantly reduce spacecraft cost, weight, and design complexity. However, the application of IMA principles introduces significant challenges, as the data network must accommodate traffic of mixed criticality and performance levels - potentially all related to the same shared computer hardware. Because individual network technologies are rarely so competent, the development of truly integrated network architectures often proves unreasonable. Several different types of networks are utilized - each suited to support a specific vehicle function. Critical functions are typically driven by precise timing loops, requiring networks with strict guarantees regarding message latency (i.e. determinism) and fault-tolerance. Alternatively, non-critical systems generally employ data networks prioritizing flexibility and high performance over reliable operation. Switched Ethernet has seen widespread success filling this role in terrestrial applications. Its high speed, flexibility, and the availability of inexpensive commercial off-the-shelf (COTS) components make it desirable for inclusion in spacecraft platforms. Basic Ethernet configurations have been incorporated into several preexisting aerospace projects, including both the Space Shuttle and International Space Station (ISS). However, classical switched Ethernet cannot provide the high level of network

  8. The role of volume charging of dielectrics in the occurrence of electrostatic discharges on spacecraft

    Science.gov (United States)

    Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

    2016-07-01

    Most recent works consider the occurrence of electrostatic discharges (ESD) on the surface of the spacecraft due to spacecraft charging as a consequence of its surface interaction with the surrounding space plasma and solar radiation [1]. At the same time, low-orbit spacecraft are simultaneously exposed to the hot magnetospheric plasma with the typical energies of the particles ~ 0.1 - 50 keV and to the particles of the Earth radiation belts (ERB) with a typical energy in the range of 0.1-10 MeV. Electrons of ERB with these energies penetrate into spacecraft dielectrics on the order of a few millimeters in depth and create an embedded charge with their own electric field. It has been shown in a number of papers that exactly a volume charge of the electrons of ERB can be the cause of ESD on spacecraft [2,3]. In this work we present the results of calculation of the dose rate and, correspondingly, the radiation conductivity in a typical spacecraft dielectrics, arising under the action of the hot magnetospheric plasma and electrons of ERB. Using software packages based on Monte Carlo methods and on the solution of equations of charge transport in spacecraft dielectrics, it is shown that in a number of areas of the Earth's magnetosphere the ESD can occur under the action of the ERB electrons. The results of present work can provide a basis for creation of the standard, characterizing the emergence of ESR on spacecraft due to volume charging of dielectrics and describing the methods of laboratory tests of spacecraft dielectrics. L.S. Novikov, A.A. Makletsov, and V.V. Sinolits, Comparison of Coulomb-2, NASCAP-2K, MUSCAT and SPIS codes for geosynchronous spacecraft charging, Advances in Space Research, 2016, V. 57, Is. 2, pp. 671-680. Wrenn G.L., Smith R.J.K. The ESD Threat to GEO Satellites: Empirical Models for Observed Effects Due to Both Surface and Internal Charging. Proc. ESA Symp. "Environment Modelling for Space-based Applications", ESTEC Noordwijk, The

  9. Developing Techniques for Spacecraft Noise Removal in Preparation for Solar Probe Plus

    Science.gov (United States)

    Bowen, T. A.; Bale, S. D.

    2015-12-01

    Many satellite magnetometers easily observe non-environmental fields generated by spacecraft electronics and mechanisms. The dominant sources of spacecraft noise differ between various missions. Accordingly, a variety of techniques are employed in removing such noise from science-level magnetic field data. We present several example sources of spacecraft noise, including reaction wheels and instrument power supplies, as well as the accompanying observational signatures present in the magnetic field data. Several potential algorithms are proposed to remove this contaminant noise. These algorithms demonstrate the effect of spacecraft noise on interpreting high precision magnetic field measurements. These noise sources and algorithms are highly relevant to future missions such as Solar Probe Plus and Solar Orbiter.

  10. 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.

  11. Embedded spacecraft thermal control using ultrasonic consolidation

    Science.gov (United States)

    Clements, Jared W.

    Research has been completed in order to rapidly manufacture spacecraft thermal control technologies embedded in spacecraft structural panels using ultrasonic consolidation. This rapid manufacturing process enables custom thermal control designs in the time frame necessary for responsive space. Successfully embedded components include temperature sensors, heaters, wire harnessing, pre-manufactured heat pipes, and custom integral heat pipes. High conductivity inserts and custom integral pulsating heat pipes were unsuccessfully attempted. This research shows the viability of rapid manufacturing of spacecraft structures with embedded thermal control using ultrasonic consolidation.

  12. 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.

  13. Interstellar dust. Evidence for interstellar origin of seven dust particles collected by the Stardust spacecraft.

    Science.gov (United States)

    Westphal, Andrew J; Stroud, Rhonda M; Bechtel, Hans A; Brenker, Frank E; Butterworth, Anna L; Flynn, George J; Frank, David R; Gainsforth, Zack; Hillier, Jon K; Postberg, Frank; Simionovici, Alexandre S; Sterken, Veerle J; Nittler, Larry R; Allen, Carlton; Anderson, David; Ansari, Asna; Bajt, Saša; Bastien, Ron K; Bassim, Nabil; Bridges, John; Brownlee, Donald E; Burchell, Mark; Burghammer, Manfred; Changela, Hitesh; Cloetens, Peter; Davis, Andrew M; Doll, Ryan; Floss, Christine; Grün, Eberhard; Heck, Philipp R; Hoppe, Peter; Hudson, Bruce; Huth, Joachim; Kearsley, Anton; King, Ashley J; Lai, Barry; Leitner, Jan; Lemelle, Laurence; Leonard, Ariel; Leroux, Hugues; Lettieri, Robert; Marchant, William; Ogliore, Ryan; Ong, Wei Jia; Price, Mark C; Sandford, Scott A; Sans Tresseras, Juan-Angel; Schmitz, Sylvia; Schoonjans, Tom; Schreiber, Kate; Silversmit, Geert; Solé, Vicente A; Srama, Ralf; Stadermann, Frank; Stephan, Thomas; Stodolna, Julien; Sutton, Stephen; Trieloff, Mario; Tsou, Peter; Tyliszczak, Tolek; Vekemans, Bart; Vincze, Laszlo; Von Korff, Joshua; Wordsworth, Naomi; Zevin, Daniel; Zolensky, Michael E

    2014-08-15

    Seven particles captured by the Stardust Interstellar Dust Collector and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream. More than 50 spacecraft debris particles were also identified. The interstellar dust candidates are readily distinguished from debris impacts on the basis of elemental composition and/or impact trajectory. The seven candidate interstellar particles are diverse in elemental composition, crystal structure, and size. The presence of crystalline grains and multiple iron-bearing phases, including sulfide, in some particles indicates that individual interstellar particles diverge from any one representative model of interstellar dust inferred from astronomical observations and theory.

  14. Reconfigurable modular computer networks for spacecraft on-board processing

    Science.gov (United States)

    Rennels, D. A.

    1978-01-01

    The core electronics subsystems on unmanned spacecraft, which have been sent over the last 20 years to investigate the moon, Mars, Venus, and Mercury, have progressed through an evolution from simple fixed controllers and analog computers in the 1960's to general-purpose digital computers in current designs. This evolution is now moving in the direction of distributed computer networks. Current Voyager spacecraft already use three on-board computers. One is used to store commands and provide overall spacecraft management. Another is used for instrument control and telemetry collection, and the third computer is used for attitude control and scientific instrument pointing. An examination of the control logic in the instruments shows that, for many, it is cost-effective to replace the sequencing logic with a microcomputer. The Unified Data System architecture considered consists of a set of standard microcomputers connected by several redundant buses. A typical self-checking computer module will contain 23 RAMs, two microprocessors, one memory interface, three bus interfaces, and one core building block.

  15. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

  16. Mirage Fire Sensor for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft fires create exception risks to crew members. There is usually no place to escape. Even small amounts of hardware damage can compromise a mission. The...

  17. Passive Wireless Sensors for Spacecraft Applications Project

    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...

  18. High Efficiency Synchronous Rectification in Spacecraft

    Science.gov (United States)

    Krauhamer, S.; Das, R.; Vorperian, V.; White, J.; Bennett, J.; Rogers, D.

    1993-01-01

    This paper examines the implementaion of MOSFETs as synchronous rectifiers which results in a substantial improvement in power processing efficency and therefore may result in significant reduction of spacecraft mass and volum for the same payload.

  19. Fermi FT2 Spacecraft Pointing Files

    Data.gov (United States)

    National Aeronautics and Space Administration — This utility permits you to download the most current version of the spacecraft (FT2) file predicting the LAT's pointing for a given mission week. The FT2 file is a...

  20. Spacecraft Magnetic Cleanliness Prediction and Control

    Science.gov (United States)

    Weikert, S.; Mehlem, K.; Wiegand, A.

    2012-05-01

    The paper describes a sophisticated and realistic control and prediction method for the magnetic cleanliness of spacecraft, covering all phases of a project till the final system test. From the first establishment of the so-called magnetic moment allocation list the necessary boom length can be determined. The list is then continuously updated by real unit test results with the goal to ensure that the magnetic cleanliness budget is not exceeded at a given probability level. A complete example is described. The synthetic spacecraft modeling which predicts only quite late the final magnetic state of the spacecraft is also described. Finally, the most important cleanliness verification, the spacecraft system test, is described shortly with an example. The emphasis of the paper is put on the magnetic dipole moment allocation method.

  1. Global 4-D trajectory optimization for spacecraft

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Global 4-D trajectory(x,y,z,t)is optimized for a spacecraft,which is launched from the Earth to fly around the Sun,just as star-drift of 1437 asteroids in the solar system.The spacecraft trajectory is controlled by low thrust.The performance index of optimal trajectory is to maximize the rendezvous times with the intermediate asteroids,and also maximize the final mass.This paper provides a combined algorithm of global 4-D trajectory optimization.The algorithm is composed of dynamic programming and two-point-boundary algorithm based on optimal control theory.The best 4-D trajectory is obtained:the spacecraft flies passing 55 asteroids,and rendezvous with(following or passing again)asteroids for 454 days,and finally rendezvous with the asteroid 2005SN25 on the day 60521(MJD),the final mass of the spacecraft is 836.53 kg.

  2. A Sustainable Spacecraft Component Database Solution Project

    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...

  3. Odor Control in Spacecraft Waste Management Project

    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...

  4. Applications of Multifunctional Structures to Small Spacecraft

    OpenAIRE

    DiPalma, John; Preble, Jeff; Schoenoff, Mike; Motoyama, Stephen; Guerrero, James; Burks, Capt. Russell

    2004-01-01

    A process for the design and fabrication of multifunctional structures has been developed to increase the utility and efficiency of spacecraft. The process addresses the unique requirements associated with small spacecraft and other highly integrated systems. By integrating items such as electrical conductors for signals and power, thermal control elements, and materials for radiation and EMI shielding, these multifunctional structures offer benefits in terms of mass savings, reduced parts co...

  5. Lunar Scout Two spacecraft gravity experiment

    Science.gov (United States)

    Cheng, Andrew F.

    1993-01-01

    Measurement of the gravity field of the Moon has a high science priority because of its implications for the internal structure and thermal history of the Moon, and it has a high priority for future exploration activities because of the influence of lunar gravity on spacecraft navigation and orbit maintenance. The current state of knowledge in the lunar gravity field (and the uncertainty in the knowledge) is based primarily on data accumulated from the Lunar Orbiter and Apollo programs. Data are sparse and emphasize the equatorial band (+/- 30 deg) on the near side of the Moon. There are no tracking data on the far side and only the Lunar Orbiter 5 provides a small amount of high inclination data. A host of gravity models developed from different combinations of tracking data have large discrepancies in their predictions of spacecraft motion and orbit lifetimes. There are also large disagreements in the Mercator projections of the gravity acceleration from each model, especially on the far side, where the contours tend to have no obvious relationship with the local topography. The science and engineering requirements for global gravity field mapping will be satisfied with continuous radio metric tracking of Lunar Scout 1 in a low polar orbit using the Deep Space Network and Lunar Scout 2 in a high elliptical orbit. The gravity field of the Moon will be mapped during the Scout Program using a two spacecraft concept. In the two spacecraft concept, one spacecraft is placed in a high altitude eccentric orbit while the second spacecraft is in a low altitude polar orbit. The gravity experiment requires a radio frequency that will permit two-way Doppler tracking between the spacecraft and the Deep Space Network (DSN). Both spacecraft carry NASA standard transponder systems for data transmission to Earth as well as for tracking and orbit determination. Data sufficient to produce a gravity field map could be acquired within one month with this system.

  6. Heat pipes for spacecraft temperature control: Their usefulness and limitations

    Science.gov (United States)

    Ollendorf, S.; Stipandic, E.

    1972-01-01

    Heat pipes are used in spacecraft to equalize the temperature of structures and maintain temperature control of electronic components. Information is provided for a designer on: (1) a typical mounting technique, (2) choices available in wick geometries and fluids, (3) tests involved in flight-qualifying the design, and (4) heat pipe limitations. An evaluation of several heat pipe designs showed that the behavior of heat pipes at room temperature does not necessarily correlate with the classic equations used to predict their performance. They are sensitive to such parameters as temperature, fluid inventory, orientation, and noncondensable gases.

  7. 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.

  8. 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.

  9. ARIEL: an ESA M4 mission candidate

    Science.gov (United States)

    Puig, L.; Pilbratt, G. L.; Heske, A.; Escudero Sanz, I.; Crouzet, P.-E.

    2016-07-01

    The Atmospheric Remote sensing Infrared Exoplanet Large survey (ARIEL) mission is an M-class mission candidate within the science program Cosmic Vision of the European Space Agency (ESA). It was selected in June 2015 as one of three candidates to enter an assessment phase (phase 0/A). This process involves the definition of science and mission requirements as well as a preliminary model payload, and an internal Concurrent Design Facility (CDF) study providing the input to parallel industrial studies (in progress since 2016). After this process, the three candidates will be reviewed and in mid-2017 one of them will be selected as the M4 mission for launch in 2026. ARIEL is a survey-type mission dedicated to the characterisation of exoplanetary atmospheres. Using the differential technique of transit spectroscopy, ARIEL will obtain transmission and/or emission spectra of the atmospheres of a large and diverse sample of known exoplanets (~500) covering a wide range of masses, densities, equilibrium temperatures, orbital properties and host-star characteristics. This will include hot Jupiters to warm Super-Earths, orbiting M5 to F0 stars. This paper describes critical requirements, and reports on the results of the Concurrent Design Facility (CDF) study that was conducted in June / July 2015, providing a description of the resulting spacecraft design. It will employ a 0.7 m x 1.1 m off-axis three mirror telescope, feeding four photometric channels in the VNIR range (0.5-1.95 μm) and an IR spectrometer covering 1.95-7.8 μm.

  10. Shape, thermal and surface properties determination of a candidate spacecraft target asteroid (175706) 1996 FG3

    Science.gov (United States)

    Yu, LiangLiang; Ji, Jianghui; Wang, Su

    2014-04-01

    In this paper, a 3D convex shape model of (175706) 1996 FG3, which consists of 2040 triangle facets and 1022 vertices, is derived from the known light curves. The best-fitting orientation of the asteroid's spin axis is determined to be λ = 237.27° and β = -83.8° considering the observation uncertainties, and its rotation period is ˜3.5935 h. Using the derived shape model, we adopt the so-called advanced thermophysical model (ATPM) to fit three published sets of mid-infrared observations of 1996 FG3, so as to evaluate its surface properties. Assuming the primary and the secondary bear identical shape, albedo, thermal inertia and surface roughness, the best-fitting parameters are obtained from the observations. The geometric albedo and effective diameter of the asteroid are reckoned to be pv = 0.045 ± 0.002, D_eff=1.69^{+0.05}_{-0.02} km. The diameters of the primary and secondary are determined to be D1=1.63^{+0.04}_{-0.03} km and D2=0.45^{+0.04}_{-0.03} km, respectively. The surface thermal inertia Γ is derived to be a low value of 80 ± 40 Jm-2 s-0.5 K-1 with a roughness fraction fR of 0.8^{+0.2}_{-0.4}. This indicates that the primary possibly has a regolith layer on its surface, which is likely to be covered by a mixture of dust, fragmentary rocky debris and sand. The minimum regolith depth is estimated to be 5-20 mm from the simulations of subsurface temperature distribution, indicating that 1996 FG3 could be a very suitable target for a sample return mission.

  11. 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; Toth, Balazs; Legros, Guillaume; Eigenbrod, Christian; Smirnov, Nickolay; Fujita, Osamu; Jomaas, Grunde

    2014-01-01

    An international collaborative program is underway to address open issues in spacecraft fire safety. Because of limited access to long-term low-gravity conditions and the small volume generally allotted for these experiments, there have been relatively few experiments that directly study spacecraft fire safety under low-gravity conditions. Furthermore, none of these experiments have studied sample sizes and environment conditions typical of those expected in a spacecraft fire. The major constraint has been the size of the sample, with prior experiments limited to samples of the order of 10 cm in length and width or smaller. This lack of experimental data forces spacecraft designers to base their designs and safety precautions on 1-g understanding of flame spread, fire detection, and suppression. However, low-gravity combustion research has demonstrated substantial differences in flame behavior in low-gravity. This, combined with the differences caused by the confined spacecraft environment, necessitates practical scale spacecraft fire safety research to mitigate risks for future space missions. To address this issue, a large-scale spacecraft fire experiment is under development by NASA and an international team of investigators. This poster presents the objectives, status, and concept of this collaborative international project (Saffire). The project plan is to conduct fire safety experiments on three sequential flights of an unmanned ISS re-supply spacecraft (the Orbital Cygnus vehicle) after they have completed their delivery of cargo to the ISS and have begun their return journeys to earth. On two flights (Saffire-1 and Saffire-3), the experiment will consist of a flame spread test involving a meter-scale sample ignited in the pressurized volume of the spacecraft and allowed to burn to completion while measurements are made. On one of the flights (Saffire-2), 9 smaller (5 x 30 cm) samples will be tested to evaluate NASAs material flammability screening tests

  12. An LDEF follow-on spacecraft concept

    Science.gov (United States)

    Keller, Vernon; Breazeale, Larry; Perkinson, Don; Kinard, William H.

    1995-02-01

    The successful flight, retrieval, and analyses of the Long Duration Exposure Facility (LDEF) experiments demonstrated the value of long duration space exposure for a broad spectrum of science and engineering investigations. The original LDEF was an excellent gravity gradient spacecraft, but because of its 9 m length and 9,700 kg mass it was difficult to manifest on the Shuttle, for either launch or retrieval, in conjunction with other payloads. This paper discusses an LDEF follow-on spacecraft concept whose short stowed length (approximately 3 m) greatly improves Shuttle manifesting opportunities while still providing very large surface area exposure for experiments. Deployable 'wings' on each end of the short, 'cylindrical' main body of this new spacecraft provide the means for gravity gradient stabilization while greatly increasing the spacecraft surface area. The center section of the spacecraft is oriented with the end faces of the twelve sided, 4.2 m diameter 'cylinder' perpendicular to the velocity vector thus providing large areas for experiments in both the ram and anti-ram directions as well as additional exposure area around the periphery of the cylinder. When deployed and properly oriented with the Shuttle's Remote Manipulator System (RMS), both wings of the spacecraft are oriented edge on to the direction of motion and lie in the plane which contains the local gravity vector. The relatively thin wings readily accommodate dual side exposure of glass plate stacks for cosmic ray detection. Flat surfaces mounted normal to and on the periphery of the wings provide additional areas in both the ram and anti-ram directions for cosmic dust, micrometeoroid, and orbital debris collection free of contamination from 'splatter' off secondary surfaces. The baseline concept provides enhancements not available on the original LDEF such as solar array generated electrical power and data telemetry. Status of the efforts to promote support for and ultimately space flight

  13. 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.

  14. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

  15. Spacecraft Design Program at the Naval Postgraduate School

    OpenAIRE

    Agrawal, B.N.

    2005-01-01

    This paper presents a review of the spacecraft design program at the Naval Postgraduate School. This program is part of the space systems engineering curriculum. In this curriculum, the students take at least one course for each spacecraft subsystem. The spacecraft design is a three course design sequence. The first course is on spacecraft design tools. The students become familiar with the spacecraft design tools that are used in the final design course. The tools include...

  16. Simulator for Testing Spacecraft Separation Devices

    Science.gov (United States)

    Johnston, Nick; Gaines, Joe; Bryan, Tom

    2006-01-01

    A report describes the main features of a system for testing pyrotechnic and mechanical devices used to separate spacecraft and modules of spacecraft during flight. The system includes a spacecraft simulator [also denoted a large mobility base (LMB)] equipped with air thrusters, sensors, and data-acquisition equipment. The spacecraft simulator floats on air bearings over an epoxy-covered concrete floor. This free-flotation arrangement enables simulation of motion in outer space in three degrees of freedom: translation along two orthogonal horizontal axes and rotation about a vertical axis. The system also includes a static stand. In one application, the system was used to test a bolt-retraction system (BRS) intended for separation of the lifting-body and deorbit-propulsion stages of the X- 38 spacecraft. The LMB was connected via the BRS to the static stand, then pyrotechnic devices that actuate the BRS were fired. The separation distance and acceleration were measured. The report cites a document, not yet published at the time of reporting the information for this article, that is said to present additional detailed information.

  17. Study of the space environmental effects on spacecraft engineering materials

    Science.gov (United States)

    Obrien, Susan K.; Workman, Gary L.; Smith, Guy A.

    1995-01-01

    The issue of the effects of the space environment on spacecraft needs to be understood for the long term exposure of structures in space. In order to better understand the effect of these hostile phenomena on spacecraft, several types of studies are worth performing in order to simulate at some level the effect of the environment. For example the effect of protons and electrons impacting structural materials are easily simulated through experiments using the Van de Graff and Pelletron accelerators currently housed at MSFC. Proton fluxes with energies of 700 KeV - 2.5 MeV can be generated and used to impinge on sample targets to determine the effects of the particles. Also the Environmental Effects Facility at MSFC has the capability to generate electron beams with energies from 700 KeV to 2.5 MeV. These facilities will be used in this research to simulate space environmental effects from energetic particles. Ultraviolet radiation, particularly less than 400 nm wavelength, is less well characterized at this time. The Environmental Effects Facility has a vacuum system dedicated to studying the effects of ultraviolet radiation on specific surface materials. This particular system was assembled in a previous study in order to perform a variety of experiments on materials proposed for the Space Station. That system has continued to function as planned and has been used in carrying out portions of the proposed study.

  18. 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

  19. 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.

  20. Printable Spacecraft: Flexible Electronic Platforms for NASA Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Atmospheric confetti. Inchworm crawlers. Blankets of ground penetrating radar. These are some of the unique mission concepts which are enabled by a printable...

  1. The MSAT spacecraft of Telesat Mobile Inc.

    Science.gov (United States)

    Bertenyi, E.

    The MSAT spacecraft of the Canadian mobile satellite operator, Telesat Mobile Inc. (TMI) is described. When launched in 1994, the large geostationary MSAT spacecraft which is currently under construction by Hughes Aircraft Co. and Spar Aerospace Ltd. will enable TMI to provide mobile and transportable communications services to its customers even in the most remote parts of the North American continent. The main elements of TMI's mobile satellite system (described in a companion paper) are the space segment and the ground segment. TMI's space segment will employ one of two nearly identical satellites, one of which will be owned and operated by TMI, the other by the U.S. mobile satellite operator, American Mobile Satellite Corporation (AMSC). The two companies are participating in a joint spacecraft procurement in order to reduce the nonrecurring costs and to ensure system compatibility between the two systems; and they have also agreed to provide in-orbit backup to each other in the event of a catastrophic satellite failure. The program status, performance requirements, main parameters, and configuration of the MSAT spacecraft are reviewed. The major features of the communications subsystem are discussed in some detail, and a brief summary is presented of the spacecraft service module. Key technology items include the L-band RF power amplifier, which must operate with a high DC to RF power efficiency and generate low intermodulation when loaded with multi-carrier signals; and the large diameter deployable L-band antenna. The development status and expected performance of these spacecraft components is examined.

  2. 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.

  3. 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

  4. Large Scale Experiments on Spacecraft Fire Safety

    DEFF Research Database (Denmark)

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

    2012-01-01

    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......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...

  5. A Reconfigurable Communications System for Small Spacecraft

    Science.gov (United States)

    Chu, Pong P.; Kifle, Muli

    2004-01-01

    Two trends of NASA missions are the use of multiple small spacecraft and the development of an integrated space network. To achieve these goals, a robust and agile communications system is needed. Advancements in field programmable gate array (FPGA) technology have made it possible to incorporate major communication and network functionalities in FPGA chips; thus this technology has great potential as the basis for a reconfigurable communications system. This report discusses the requirements of future space communications, reviews relevant issues, and proposes a methodology to design and construct a reconfigurable communications system for small scientific spacecraft.

  6. DELPHI: Higgs candidate

    CERN Multimedia

    2001-01-01

    This track is an example of real data collected from the DELPHI detector on the Large Electron-Positron (LEP) collider at CERN, which ran between 1989 and 2000. Its topology is compatible with what is expected from the associated production of a Z boson and Higgs boson of mass 113 GeV that each decay into two jets. A different pairing of the jets could lead to an interpretation compatible with the production of two Z bosons.

  7. Science Benefits of Onboard Spacecraft Navigation

    Science.gov (United States)

    Cangahuala, Al; Bhaskaran, Shyam; Owen, Bill

    2012-01-01

    Primitive bodies (asteroids and comets), which have remained relatively unaltered since their formation, are important targets for scientific missions that seek to understand the evolution of the solar system. Often the first step is to fly by these bodies with robotic spacecraft. The key to maximizing data returns from these flybys is to determine the spacecraft trajectory relative to the target body-in short, navigate the spacecraft- with sufficient accuracy so that the target is guaranteed to be in the instruments' field of view. The most powerful navigation data in these scenarios are images taken by the spacecraft of the target against a known star field (onboard astrometry). Traditionally, the relative trajectory of the spacecraft must be estimated hours to days in advance using images collected by the spacecraft. This is because of (1)!the long round-trip light times between the spacecraft and the Earth and (2)!the time needed to downlink and process navigation data on the ground, make decisions based on the result, and build and uplink instrument pointing sequences from the results. The light time and processing time compromise navigation accuracy considerably, because there is not enough time to use more accurate data collected closer to the target-such data are more accurate because the angular capability of the onboard astrometry is essentially constant as the distance to the target decreases, resulting in better "plane-of- sky" knowledge of the target. Excellent examples of these timing limitations are high-speed comet encounters. Comets are difficult to observe up close; their orbits often limit scientists to brief, rapid flybys, and their coma further restricts viewers from seeing the nucleus in any detail, unless they can view the nucleus at close range. Comet nuclei details are typically discernable for much shorter durations than the roundtrip light time to Earth, so robotic spacecraft must be able to perform onboard navigation. This onboard

  8. Pyroshock Environments Characterized for Spacecraft Missions

    Science.gov (United States)

    Hughes, William O.; McNelis, Anne M.

    1999-01-01

    Pyrotechnic shock, or pyroshock, is the transient response of a structure to loading induced by the ignition of pyrotechnic (explosive or propellant activated) devices. These devices are typically used to separate structural systems (e.g., separate a spacecraft from a launch vehicle) and deploy appendages (e.g., solar panels). Pyroshocks are characterized by high peak acceleration, high-frequency content, and short duration. Because of their high acceleration and high-frequency, pyroshocks can cause spaceflight hardware to fail. Verifying by test that spaceflight hardware can withstand the anticipated shock environment is considered essential to mission success. The Earth Observing System (EOS) AM-1 spacecraft for NASA's Mission to Planet Earth is scheduled to be launched on an Atlas IIAS vehicle in 1999, and the NASA Lewis Research Center is the launch vehicle integrator for this NASA Goddard Space Flight Center spacecraft. The EOS spacecraft was subjected to numerous ground shock tests to verify that its scientific instruments and avionics components will withstand the shock-induced vibration produced when the spacecraft separates from the launch vehicle. Shock test data from these tests represent the third largest available pyroshock database in the United States. Future spacecraft missions will directly benefit from the knowledge gained from these tests. The payload separation system used for EOS is a new system that operates by firing six separation nuts. This system was tested to verify its functional operation and to characterize the resulting shock levels. The launch vehicle contractor (Lockheed Martin Astronautics) and spacecraft contractor (Lockheed Martin Missiles & Space) completed 16 separation test firings. This resulted in an unusually large amount of pyroshock data. Typically, only one or two pyroshock test firings are performed for a spacecraft mission. Because of the size of this separation system shock database, engineers were able to perform

  9. Simultaneous Observation of Plasma Waves Detected by the Van Allen Probes Spacecraft During Close Spacecraft Separations

    Science.gov (United States)

    Hospodarsky, George; Santolik, Ondrej; Averkamp, Terrance; Bounds, Scott; Kurth, William; Kletzing, Craig; Wygant, John; Bonnell, John

    2014-05-01

    The twin Van Allen Probe spacecraft launched in August 2012 includes the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) Wave instrument that simultaneously measures three orthogonal components of the wave magnetic field and, with the support of the Electric Fields and Waves (EFW) instrument sensors, three components of the wave electric field at two locations in Earth's magnetosphere. Measuring all six wave components simultaneously allows the wave propagation parameters, such as the wave normal angle and Poynting vector, of the plasma wave emissions to be obtained. The orbit of the spacecraft are designed such that they "lap" each other roughly every 69 days, allowing observations over a range of spacecraft separations, with the closest separations on the order of 100 km. Simultaneous measurements at a range of distances between the two spacecraft provide an opportunity to investigate the scale, size and propagation characteristics of a number of plasma wave emissions associated with the Van Allen radiation belts, including whistler mode chorus. We examine these characteristics of the emissions detected by both spacecraft during separation distance of < 1000 km. Very similar small scale chorus wave packets were detected by both spacecraft when separation distances were the smallest. The similarities and differences detected by both spacecraft and their relation to separation distances will be discussed.

  10. Modular, Fault-Tolerant Electronics Supporting Space Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AeroAstro's innovative design approach for implementing reconfigurable electronics frees the spacecraft designer to concentrate on the mission at hand with...

  11. Detection of meteoroid hypervelocity impacts on the Cluster spacecraft

    Science.gov (United States)

    Vaverka, Jakub; Mann, Ingrid; Kero, Johan; De Spiegeleer, Alexandre; Hamrin, Maria; Norberg, Carol; Pitkanen, Timo; Pellinen-Wannberg, Asta

    2016-07-01

    There are several methods to measure the cosmic dust entering the Earth's atmosphere such as space-born dust detectors, meteor and HPLA radars, and optical imaging. One complementary method could be to use electric field instruments initially designed to measure electric waves. A plasma cloud generated by a hypervelocity dust impact on a spacecraft body can be detected by the electric field instruments commonly operated on the spacecraft. Since Earth-orbiting missions are generally not equipped with conventional dust detectors, the electric field instruments offer an alternative method to measure the Earth's dust environment. We present the first detection of dust impacts on one of the Earth-orbiting Cluster satellites recorded by the Wide-Band Data (WBD) instrument. We describe the concept of dust impact detection focused on specifics of the Cluster spacecraft and the WBD instrument and their influence on dust impact detection. The detected pulses are compared with theoretical shape based on the model of the recollection of plasma clouds electrons. The estimation of the size and the velocity of the impinging dust grains from the amplitude of the Cluster voltage pulses shown that such impacts can be generated by grains of radius of r = 0.1 μm impacting with the velocity v ˜100 km/s or by grains of radius r = 1 μm impacting with the velocity v ˜10 km/s. We discuss the sensitivity of this method for dust grain detection showing that grains of radius r = 0.01 μm can be detected when impacting with velocity v ˜300 km/s and grains of radius r = 10 μm with velocity v ˜1 km/s if the WBD instrument operates in the high gain level (75 dB).

  12. ALEPH: Higgs candidate

    CERN Multimedia

    Photolab

    2000-01-01

    This track is an example of real data collected from the ALEPH detector on the Large Electron-Positron (LEP) collider at CERN, which ran between 1989 and 2000. Four jets of hadrons can be seen in the detector that could have resulted from the associated production and decay of a Z0 and a Higgs boson into quark-antiquark pairs, which appear in the detector as jets of hadrons. However, other processes can produce similiar tracks so this is not conclusive evidence for the Higgs.

  13. 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.

  14. 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.

  15. 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...

  16. Reengineering the JPL Spacecraft Design Process

    Science.gov (United States)

    Briggs, C.

    1995-01-01

    This presentation describes the factors that have emerged in the evolved process of reengineering the unmanned spacecraft design process at the Jet Propulsion Laboratory in Pasadena, California. Topics discussed include: New facilities, new design factors, new system-level tools, complex performance objectives, changing behaviors, design integration, leadership styles, and optimization.

  17. 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.

  18. Fault Tolerant Techniques for Spacecraft Data Recorders

    OpenAIRE

    Anderson, Scott

    1990-01-01

    This paper presents the techniques for improving system reliability which SEAKR Engineering employs in the design of their spacecraft solid state data recorders. Briefly, these techniques include Hamming code error correction, periodic memory scrubbing, latch-up protection, excessive capacity, redundant power supplies/control/bus circuits, microcode protection, and shielding.

  19. 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 ...

  20. Gamma radiation survey of the LDEF spacecraft

    Science.gov (United States)

    Phillips, G. W.; King, S. E.; August, R. A.; Ritter, J. C.; Cutchin, J. H.; Haskins, P. S.; Mckisson, J. E.; Ely, D. W.; Weisenberger, A. G.; Piercey, R. B.

    1992-01-01

    The retrieval of the Long Duration Exposure Facility spacecraft in January 1990 after nearly six years in orbit offered a unique opportunity to study the long term buildup of induced radioactivity in the variety of materials on board. We conducted the first complete gamma-ray survey of a large spacecraft on LDEF shortly after its return to earth. A surprising observation was the Be-7 activity which was seen primarily on the leading edge of the satellite, implying that it was picked up by LDEF in orbit. This is the first known evidence for accretion of a radioactive isotope onto an orbiting spacecraft. Other isotopes observed during the survey, the strongest being Na-22, are all attributed to activation of spacecraft components. Be-7 is a spallation product of cosmic rays on nitrogen and oxygen in the upper atmosphere. However, the observed density is much greater than expected due to cosmic-ray production in situ. This implies transport of Be-7 from much lower altitudes up to the LDEF orbit.

  1. A Self-Tuning Kalman Filter for Autonomous Spacecraft Navigation

    Science.gov (United States)

    Truong, Son H.

    1998-01-01

    Most navigation systems currently operated by NASA are ground-based, and require extensive support to produce accurate results. Recently developed systems that use Kalman Filter and Global Positioning System (GPS) data for orbit determination greatly reduce dependency on ground support, and have potential to provide significant economies for NASA spacecraft navigation. Current techniques of Kalman filtering, however, still rely on manual tuning from analysts, and cannot help in optimizing autonomy without compromising accuracy and performance. This paper presents an approach to produce a high accuracy autonomous navigation system fully integrated with the flight system. The resulting system performs real-time state estimation by using an Extended Kalman Filter (EKF) implemented with high-fidelity state dynamics model, as does the GPS Enhanced Orbit Determination Experiment (GEODE) system developed by the NASA Goddard Space Flight Center. Augmented to the EKF is a sophisticated neural-fuzzy system, which combines the explicit knowledge representation of fuzzy logic with the learning power of neural networks. The fuzzy-neural system performs most of the self-tuning capability and helps the navigation system recover from estimation errors. The core requirement is a method of state estimation that handles uncertainties robustly, capable of identifying estimation problems, flexible enough to make decisions and adjustments to recover from these problems, and compact enough to run on flight hardware. The resulting system can be extended to support geosynchronous spacecraft and high-eccentricity orbits. Mathematical methodology, systems and operations concepts, and implementation of a system prototype are presented in this paper. Results from the use of the prototype to evaluate optimal control algorithms implemented are discussed. Test data and major control issues (e.g., how to define specific roles for fuzzy logic to support the self-learning capability) are also

  2. Adsorption processes in spacecraft environmental control and life support systems.

    Science.gov (United States)

    DallBauman, L A; Finn, J E

    1999-01-01

    The environmental control and life support system on a spacecraft maintains a safe and comfortable environment in which the crew can live and work by supplying oxygen and water and by removing carbon dioxide, water vapor, and trace contaminants from cabin air. Although open-loop systems have been used successfully in the past for short-duration missions, the economics of current and future long-duration missions in space will make nearly complete recycling of air and water imperative. A variety of operations will be necessary to achieve the goal of nearly complete recycling. These include separation and reduction of carbon dioxide, removal of trace gas-phase contaminants, recovery and purification of humidity condensate, purification and polishing of wastewater streams, and others. Several of these can be performed totally or in part by adsorption processes. These processes are good candidates to perform separations and purifications in space due to their gravity independence, high reliability, relative high energy efficiency, design flexibility, technological maturity, and regenerative nature. For these reasons, adsorption has historically played a key role in life support on U.S. and Russian piloted spacecraft. Among the life support applications that can be achieved through use of adsorption technology are removal of trace contaminants and carbon dioxide from cabin air and recovery of potable water from waste streams. In each of these cases adsorption technology has been selected for use onboard the International Space Station. The requirements, science, and hardware for these applications are discussed. Human space exploration may eventually lead to construction of planetary habitats. These habitats may provide additional opportunities for use of adsorption processes, such as control of greenhouse gas composition, and may have different resources available to them, such as gases present in the planetary atmosphere. Separation and purification processes based on

  3. Understanding compressible turbulence in the solar wind with multipoint density measurements derived from spacecraft potential

    Science.gov (United States)

    Roberts, Owen

    2016-04-01

    Measurements of spacecraft potential can often be used to derive the electron number density with higher time resolution than is typically available with plasma instruments. On board the Cluster spacecraft the potential is measured with the Electric Fields and Waves instrument (EFW) which consists of four booms in the spin plane of the spacecraft. Consequently the potential measurement is affected by spin and wake effects. This makes the study of frequencies larger than the spin frequency challenging. To overcome these caveats a statistical model of the potential is obtained as a function of the angle the spacecraft is facing. When this variation is known it can be removed from the potential data, resulting in a much more accurate determination of the electron density and a cleaner power spectrum. Spikes at harmonics of the spin frequency can be removed without the need to use a notch filter on the time series. The treated data can then be used as an input to the k-filtering technique, which has previously been applied to the incompressible components of the magnetic field. This allows determination of the three dimensional power distribution in wave space as well as the wavevectors and plasma frame frequencies. Results for the compressible component (using electron density and magnitude of the magnetic field as inputs) and the incompressible component (three components of the magnetic field) will be compared.

  4. Electoral Systems and Candidate Selection

    NARCIS (Netherlands)

    Hazan, Reuven Y.; Voerman, Gerrit

    2006-01-01

    Electoral systems at the national level and candidate selection methods at the party level are connected, maybe not causally but they do influence each other. More precisely, the electoral system constrains and conditions the parties' menu of choices concerning candidate selection. Moreover, in ligh

  5. The PocketSpacecraft.com Integrated eXploration Environment (PIXE)

    Science.gov (United States)

    Johnson, Michael

    2015-04-01

    The PocketSpacecraft.com Integrated eXploration Environment (PIXE) is an integrated generic spacecraft design, simulation, manufacturing, and operations system for the low cost mass exploration of space by amateur and professional Principle Investigators (PIs). PIs use an online tool to design Thin-Film Spacecraft/Lander/Rovers (TF-SLRs) using a library of predefined spacecraft and mission components to specify TF-SLRs in quantities ranging from one to thousands per mission, each with a typical mass cost per TF-SLR. TF-SLR designs and missions are verified by simulation, automatically manufactured using a hybrid printed electronics process, and integrated for launch into 0.5-3U Interplanetary CubeSat motherships capable of being qualified to COSPAR Planetary Protection Category IVa or better. The Interplanetary CubeSat is launched on a standard CubeSat rideshare to an orbit suitable for deploying the TF-SLRs, and acts as a communications relay until its end of life. Data is received on earth using adapted radio telescopes and CCSDS compliant ground stations, and forwarded to a central data warehouse for download by the PI. Individual elements of the concept have been demonstrated on earth and in orbit during 2013 and 2014. A full proof of concept mission 'Pocket Spacecraft: Mission to the Moon' has been traditionally and crowd funded and is being prepared for flight with the goal of achieving low lunar orbit in 2016.

  6. High-Performance Fire Detector for Spacecraft Project

    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...

  7. Lunar Module 5 mated with Spacecraft Lunar Module Adapter (SLA)

    Science.gov (United States)

    1969-01-01

    Interior view of the Kennedy Space Center's (KSC) Manned Spacecraft Operations Building showing Lunar Module 5 mated to its Spacecraft Lunar Module Adapter (SLA). LM-5 is scheduled to be flown on the Apollo 11 lunar landing mission.

  8. Spacecraft Formation Orbit Estimation Using WLPS-Based Localization

    Directory of Open Access Journals (Sweden)

    Shu Ting Goh

    2011-01-01

    Full Text Available This paper studies the implementation of a novel wireless local positioning system (WLPS for spacecraft formation flying to maintain high-performance spacecraft relative and absolute position estimation. A WLPS equipped with antenna arrays allows each spacecraft to measure the relative range and coordinate angle(s of other spacecraft located in its coverage area. The dynamic base station and the transponder of WLPS enable spacecraft to localize each other in the formation. Because the signal travels roundtrip in WLPS, and due to the high spacecraft velocities, the signal transmission time delay reduces the localization performance. This work studies spacecraft formation positions estimation performance assuming that only WLPS is available onboard. The feasibility of estimating the spacecraft absolute position using only one-dimensional antenna array is also investigated. The effect of including GPS measurements in addition to WLPS is studied and compared to a GPS standalone system.

  9. NASA STD-4005: The LEO Spacecraft Charging Design Standard

    Science.gov (United States)

    Ferguson, Dale C.

    2006-01-01

    Power systems with voltages higher than about 55 volts may charge in Low Earth Orbit (LEO) enough to cause destructive arcing. The NASA STD-4005 LEO Spacecraft Charging Design Standard will help spacecraft designers prevent arcing and other deleterious effects on LEO spacecraft. The Appendices, an Information Handbook based on the popular LEO Spacecraft Charging Design Guidelines by Ferguson and Hillard, serve as a useful explanation and accompaniment to the Standard.

  10. Wireless Intra-Spacecraft Communication: The Benefits and the Challenges

    Science.gov (United States)

    Zheng, Will H.; Armstrong, John T.

    2010-01-01

    In this paper we present a systematic study of how intra-spacecraft wireless communication can be adopted to various subsystems of the spacecraft including C&DH (Command & Data Handling), Telecom, Power, Propulsion, and Payloads, and the interconnects between them. We discuss the advantages of intra-spacecraft wireless communication and the disadvantages and challenges and a proposal to address them.

  11. Modeling of an AC Power System for High Power Spacecraft

    Science.gov (United States)

    Stankovic, A. V.; Birchenough, A. G.; Kenny, B.; Kimnach, G.

    2004-02-01

    This paper presents an analysis and simulation of an AC power system for a high power spacecraft that primarily supplies rectified loads. Two different configurations consisting of a three-phase PM synchronous generator and an associated power electronics converter are compared and analyzed. The first configuration consists of a three-phase PM synchronous generator and a three-phase diode bridge supplying a DC load. The second configuration consists of a three-phase PM synchronous generator and a three-phase PWM rectifier supplying the DC load. The modeling equations for both systems are derived. The comparisons between the two different configurations are summarized in a table in terms of efficiency, harmonic content and DC voltage ripple. The simulation results obtained by using SIMULINK are presented.

  12. Fundamentals of spacecraft attitude determination and control

    CERN Document Server

    Markley, F Landis

    2014-01-01

    This book explores topics that are central to the field of spacecraft attitude determination and control. The authors provide rigorous theoretical derivations of significant algorithms accompanied by a generous amount of qualitative discussions of the subject matter. The book documents the development of the important concepts and methods in a manner accessible to practicing engineers, graduate-level engineering students and applied mathematicians. It includes detailed examples from actual mission designs to help ease the transition from theory to practice, and also provides prototype algorithms that are readily available on the author’s website. Subject matter includes both theoretical derivations and practical implementation of spacecraft attitude determination and control systems. It provides detailed derivations for attitude kinematics and dynamics, and provides detailed description of the most widely used attitude parameterization, the quaternion. This title also provides a thorough treatise of attitu...

  13. FORTE spacecraft vibration mitigation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. The Anomalous Acceleration of the Pioneer Spacecrafts

    CERN Document Server

    de Diego, Jose A

    2008-01-01

    Radiometric data from the Pioneer 10 and 11 spacecrafts have revealed an unexplained constant acceleration of a_A = (8.74 +/- 1.33) x 10^(-10) m s^(-2) towards the Sun, also known as the Pioneer anomaly. Different groups have analyzed the Pioneer data and have got the same results, which rules out computer programming and handling errors. Attempts to explain this phenomenon arguing intrinsic causes on-board the spacecrafts failed or have lead to inconclusive results. Therefore, the Pioneer anomalous acceleration has motivated the interest of researchers to find out explanations that could bring insight upon the forces acting in the outer Solar Systems or a hint to discover new natural laws.

  15. 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.

  16. Microgravity Flammability Experiments for Spacecraft Fire Safety

    DEFF Research Database (Denmark)

    Legros, Guillaume; Minster, Olivier; Tóth, Balazs;

    2012-01-01

    -supply vehicle like the ATV or Orbital’s Cygnus, a series of supporting experiments are being planned and conducted by the team members. In order to answer the appropriate scientific and engineering problems relevant for spacecraft fire safety, a canonical scenario that can improve the understanding of flame...... spread, and thus also the modeling thereof, in realistic conditions is described. Some of the parameters governing the flame spread are also identified and their scaling against the dimensions of the test specimen is briefly questioned. Then several of the current and scheduled efforts are presented...... in terms of their relevance for the flame spread problem. Further, it is explained how the results can be combined to enhance the understanding of fire spread in the real scale configuration and thus improve the fire safety onboard spacecrafts. The results and particularly the ones from the large scale...

  17. Spacecraft Will Communicate "on the Fly"

    Science.gov (United States)

    Laufenberg, Lawrence

    2003-01-01

    As NASA probes deeper into space, the distance between sensor and scientist increases, as does the time delay. NASA needs to close that gap, while integrating more spacecraft types and missions-from near-Earth orbit to deep space. To speed and integrate communications from space missions to scientists on Earth and back again. NASA needs a comprehensive, high-performance communications network. To this end, the CICT Programs Space Communications (SC) Project is providing technologies for building the Space Internet which will consist of large backbone network, mid-size access networks linked to the backbones, and smaller, ad-hoc network linked to the access network. A key component will be mobile, wireless networks for spacecraft flying in different configurations.

  18. Gravity Gradient Tensor Eigendecomposition for Spacecraft Positioning

    CERN Document Server

    Chen, Pei; Han, Chao

    2016-01-01

    In this Note, a new approach to spacecraft positioning based on GGT inversion is presented. The gravity gradient tensor is initially measured in the gradiometer reference frame (GRF) and then transformed to the Earth-Centered Earth-Fixed (ECEF) frame via attitude information as well as Earth rotation parameters. Matrix Eigen-Decomposition is introduced to directly translate GGT into position based on the fact that the eigenvalues and eigenvectors of GGT are simplespecific functions of spherical coordinates of the observation position. without the need of an initial position. Unlike the strategy of inertial navigation aiding, no prediction or first guess of the spacecraft position is needed. The method makes use of the J2 gravity model, and is suitable for space navigation where higher frequency terrain contributions to the GGT signals can be neglected.

  19. Kalman filtering for spacecraft attitude estimation

    Science.gov (United States)

    Lefferts, E. J.; Markley, F. L.; Shuster, M. D.

    1982-01-01

    Several schemes in current use for sequential estimation of spacecraft attitude using Kalman filters are examined. These differ according to their treatment of the attitude error, namely: using the complete four-component quaternion; using a truncated quaternion in which one of the components has been eliminated; or using a quaternion referred to approximate body-fixed axes. These schemes are examined for the case of a spacecraft carrying line-of-sight attitude sensors and three-axis gyros whose measurements are corrupted by noise on both the drift rate and the drift-rate ramp. The analysis of the covariance is carried out in detail. The historical development of Kalman filtering of attitude is reviewed.

  20. Galileo spacecraft power management and distribution system

    International Nuclear Information System (INIS)

    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

  1. Artificial Intelligence and Spacecraft Power Systems

    Science.gov (United States)

    Dugel-Whitehead, Norma R.

    1997-01-01

    This talk will present the work which has been done at NASA Marshall Space Flight Center involving the use of Artificial Intelligence to control the power system in a spacecraft. The presentation will include a brief history of power system automation, and some basic definitions of the types of artificial intelligence which have been investigated at MSFC for power system automation. A video tape of one of our autonomous power systems using co-operating expert systems, and advanced hardware will be presented.

  2. Space Robotics: What is a Robotic Spacecraft?

    OpenAIRE

    Alex Ellery

    2004-01-01

    In this first of three short papers, I introduce some of the basic concepts of space engineering with an emphasis on some specific challenging areas of research that are peculiar to the application of robotics to space development and exploration. The style of these short papers is pedagogical and this paper stresses the unique constraints that space application imposes. This first paper is thus a general introduction to the nature of spacecraft engineering and its application to robotic spac...

  3. Wheel speed management control system for spacecraft

    Science.gov (United States)

    Goodzeit, Neil E. (Inventor); Linder, David M. (Inventor)

    1991-01-01

    A spacecraft attitude control system uses at least four reaction wheels. In order to minimize reaction wheel speed and therefore power, a wheel speed management system is provided. The management system monitors the wheel speeds and generates a wheel speed error vector. The error vector is integrated, and the error vector and its integral are combined to form a correction vector. The correction vector is summed with the attitude control torque command signals for driving the reaction wheels.

  4. Nonlinear Robust Control for Spacecraft Attitude

    Directory of Open Access Journals (Sweden)

    Wang Lina

    2013-07-01

    Full Text Available Nonlinear robust control of the spacecraft attitude with the existence of external disturbances is considered. A robust attitude controller is designed based on the passivity approach the quaternion representation, which introduces the suppression vector of external disturbance into the control law and does not need angular velocity measurement. Stability conditions of the robust attitude controller are given. And the numerical simulation results show the effectiveness of the attitude controller.

  5. Building the Small Spacecraft Technology Pipeline

    OpenAIRE

    Reuther, Dr. James

    2011-01-01

    Biography - Dr. Reuther currently serves as the Acting Director for Crosscutting Capability Demonstrations in the Office of Chief Technologist of the National Aeronautics and Space Administration (NASA) Headquarters. Previously, Dr. Reuther served as the Lead of the Test and Verification (T&V) Office for the Orion spacecraft development. After graduating from the University of California Davis with a Bachelors, Masters, and Ph.D. in mechanical and aeronautical engineering, Dr. Reuther perform...

  6. Spacecraft Dynamic Characteristics While Deploying Flexible Beams

    Institute of Scientific and Technical Information of China (English)

    程绪铎; 李俊峰; 樊勇; 王照林

    2002-01-01

    The attitude dynamic equations of a spacecraft while deploying two flexible beams and the beam equations were developed from momentum theory. The dynamic equations were solved numerically using the Runge-Kutta method to calculate the vibration amplitudes of the flexible beams and the attitude angular velocity. The results show that the vibration amplitudes increase as the beam length increases or as the initial attitude angular velocity increases. The results also show that the vibration amplitudes decrease as the deployment velocity increases.

  7. 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.

  8. JBoss Middleware for Spacecraft Trajectory Operations

    Science.gov (United States)

    Stensrud, Kjell; Srinivasan, Ravi; Hamm, Dustin

    2008-01-01

    This viewgraph presentation reviews the use of middleware for spacecraft trajectory planning. It reviews the following areas and questions: 1. Project Background - What is the environment where we are considering Open Source Middleware? 2. System Architecture - What technologies and design did we apply? 3. Testing overview - What are the quality scenarios and test points? 4. Project Conclusion - What did we learn about Open Source Middleware?

  9. Additive Manufacturing: Ensuring Quality for Spacecraft Applications

    Science.gov (United States)

    Swanson, Theodore; Stephenson, Timothy

    2014-01-01

    Reliable manufacturing requires that material properties and fabrication processes be well defined in order to insure that the manufactured parts meet specified requirements. While this issue is now relatively straightforward for traditional processes such as subtractive manufacturing and injection molding, this capability is still evolving for AM products. Hence, one of the principal challenges within AM is in qualifying and verifying source material properties and process control. This issue is particularly critical for applications in harsh environments and demanding applications, such as spacecraft.

  10. THE FUTURE OF SPACECRAFT NUCLEAR PROPULSION

    OpenAIRE

    Jansen, Frank

    2014-01-01

    This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

  11. The Future of Spacecraft Nuclear Propulsion

    Science.gov (United States)

    Jansen, F.

    2014-06-01

    This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

  12. Monte Carlo random walk simulation of electron transport in confined porous TiO2 as a promising candidate for photo-electrode of nano-crystalline solar cells

    International Nuclear Information System (INIS)

    Monte Carlo continuous time random walk simulation is used to study the effects of confinement on electron transport, in porous TiO2. In this work, we have introduced a columnar structure instead of the thick layer of porous TiO2 used as anode in conventional dye solar cells. Our simulation results show that electron diffusion coefficient in the proposed columnar structure is significantly higher than the diffusion coefficient in the conventional structure. It is shown that electron diffusion in the columnar structure depends both on the cross section area of the columns and the porosity of the structure. Also, we demonstrate that such enhanced electron diffusion can be realized in the columnar photo-electrodes with a cross sectional area of ∼1 μm2 and porosity of 55%, by a simple and low cost fabrication process. Our results open up a promising approach to achieve solar cells with higher efficiencies by engineering the photo-electrode structure

  13. Time Delay Interferometry with Moving Spacecraft Arrays

    CERN Document Server

    Tinto, M; Armstrong, J W; Tinto, Massimo; Estabrook, Frank B.; Armstrong, adn J.W.

    2004-01-01

    Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-travel-times will necessarily be unequal, time-varying, and (due to aberration) have different time delays on up- and down-links. Reduction of data from moving interferometric laser arrays in solar orbit will in fact encounter non-symmetric up- and downlink light time differences that are about 100 times larger than has previously been recognized. The time-delay interferometry (TDI) technique uses knowledge of these delays to cancel the otherwise dominant laser phase noise and yields a variety of data combinations sensitive to gravitational waves. Under the assumption that the (different) up- and downlink time delays are constant, we derive the TDI expressions for those combinations that rely only on four inter-spacecraft phase measurements. We then turn to the general problem that encompasses time-dependence of the light...

  14. Spacecraft early design validation using formal methods

    International Nuclear Information System (INIS)

    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)

  15. A Functional Simulator of Spacecraft Resources

    Science.gov (United States)

    Liceaga, Carlos A.; Troutman, Patrick A.

    1997-01-01

    The SPAcecraft SIMulator (SPASIM) simulates the functions and resources of a spacecraft to quickly perform Phase A trade-off analyses and uncover any operational bottlenecks during any part of the mission. Failure modes and operational contingencies can be evaluated allowing optimization for a range of mission scenarios. The payloads and subsystems are simulated, using a hierarchy of graphical models, in terms of how their functions affect resources such as propellant, power, and data. Any of the inputs and outputs of the payloads and subsystems can be plotted during the simulation. Most trade-off analyses, including those that compare current versus advanced technology, can be performed by changing values in the parameter menus. However, when a component is replaced by one with a different functional architecture, its graphical model can also be modified or replaced by drawing from a component library. SPASIM has been validated using several spacecraft designs which were at least at the Critical Design Review level. The user and programmer guide, including figures, is available on line as a hyper text document. This is an easy-to-use and expand tool which is based on MATLAB and SIMULINK. It runs on SGI workstations and PCs under Windows 95 or NT.

  16. Ontological Modeling for Integrated Spacecraft Analysis

    Science.gov (United States)

    Wicks, Erica

    2011-01-01

    Current spacecraft work as a cooperative group of a number of subsystems. Each of these requiresmodeling software for development, testing, and prediction. It is the goal of my team to create anoverarching software architecture called the Integrated Spacecraft Analysis (ISCA) to aid in deploying the discrete subsystems' models. Such a plan has been attempted in the past, and has failed due to the excessive scope of the project. Our goal in this version of ISCA is to use new resources to reduce the scope of the project, including using ontological models to help link the internal interfaces of subsystems' models with the ISCA architecture.I have created an ontology of functions specific to the modeling system of the navigation system of a spacecraft. The resulting ontology not only links, at an architectural level, language specificinstantiations of the modeling system's code, but also is web-viewable and can act as a documentation standard. This ontology is proof of the concept that ontological modeling can aid in the integration necessary for ISCA to work, and can act as the prototype for future ISCA ontologies.

  17. Modelling of spacecraft spin period during eclipse

    Directory of Open Access Journals (Sweden)

    K.-H. Fornaçon

    2011-05-01

    Full Text Available The majority of scientific satellites investigating the Earth magnetosphere are spin stabilized. The attitude information comes usually from a sun sensor and is missing in the umbra; hence, the accurate experimental determination of vector quantities is not possible during eclipses. The spin period of the spacecraft is generally not constant during these times because the moment of inertia changes due to heat dissipation. The temperature dependence of the moment of inertia for each spacecraft has a specific signature determined by its design and distribution of mass. We developed an "eclipse-spin" model for the spacecraft spin period behaviour using magnetic field vector measurements close to the Earth, where the magnetic field is dominated by the dipole field, and in the magnetospheric lobes, where the magnetic field direction is mostly constant. The modelled spin periods give us extraordinarily good results with accumulated phase deviations over one hour of less than 10 degrees. Using the eclipse spin model satellite experiments depending on correct spin phase information can deliver science data even during eclipses. Two applications for THEMIS B, one in the lobe and the other in the lunar wake, are presented.

  18. Heliocentric phasing performance of electric sail spacecraft

    Science.gov (United States)

    Mengali, Giovanni; Quarta, Alessandro A.; Aliasi, Generoso

    2016-10-01

    We investigate the heliocentric in-orbit repositioning problem of a spacecraft propelled by an Electric Solar Wind Sail. Given an initial circular parking orbit, we look for the heliocentric trajectory that minimizes the time required for the spacecraft to change its azimuthal position, along the initial orbit, of a (prescribed) phasing angle. The in-orbit repositioning problem can be solved using either a drift ahead or a drift behind maneuver and, in general, the flight times for the two cases are different for a given value of the phasing angle. However, there exists a critical azimuthal position, whose value is numerically found, which univocally establishes whether a drift ahead or behind trajectory is superior in terms of flight time it requires for the maneuver to be completed. We solve the optimization problem using an indirect approach for different values of both the spacecraft maximum propulsive acceleration and the phasing angle, and the solution is then specialized to a repositioning problem along the Earth's heliocentric orbit. Finally, we use the simulation results to obtain a first order estimate of the minimum flight times for a scientific mission towards triangular Lagrangian points of the Sun-[Earth+Moon] system.

  19. Stability analysis of spacecraft power systems

    Science.gov (United States)

    Halpin, S. M.; Grigsby, L. L.; Sheble, G. B.; Nelms, R. M.

    1990-01-01

    The problems in applying standard electric utility models, analyses, and algorithms to the study of the stability of spacecraft power conditioning and distribution systems are discussed. Both single-phase and three-phase systems are considered. Of particular concern are the load and generator models that are used in terrestrial power system studies, as well as the standard assumptions of load and topological balance that lead to the use of the positive sequence network. The standard assumptions regarding relative speeds of subsystem dynamic responses that are made in the classical transient stability algorithm, which forms the backbone of utility-based studies, are examined. The applicability of these assumptions to a spacecraft power system stability study is discussed in detail. In addition to the classical indirect method, the applicability of Liapunov's direct methods to the stability determination of spacecraft power systems is discussed. It is pointed out that while the proposed method uses a solution process similar to the classical algorithm, the models used for the sources, loads, and networks are, in general, more accurate. Some preliminary results are given for a linear-graph, state-variable-based modeling approach to the study of the stability of space-based power distribution networks.

  20. Multiple main-belt asteroid mission options for a Mariner Mark II spacecraft

    Science.gov (United States)

    Sauer, Carl G., Jr.; Yen, Chen-Wan L.

    1990-01-01

    This paper presents the trajectory options available for a MMII spacecraft mission to asteroids and introduces systematic methods of uncovering attractive mission opportunities. The analysis presented considers multiple synchronous gravity assists of Mars and introduces a terminal resonant or phasing orbit; a concept useful for both increasing the number of asteroid rendezvous targets attainable during a launch opportunity, and also in increasing the number of potential asteroid flybys. Systematic examinations of the requirements for superior asteroidal alignments are made and a comprehensive set of asteroid rendezvous opportunities for the 1998 to 2010 period are presented. Examples of candidate missions involving one or more rendezvous and several flybys are also presented.

  1. Evaluating Fault Management Operations Concepts for Next-Generation Spacecraft: What Eye Movements Tell Us

    Science.gov (United States)

    Hayashi, Miwa; Ravinder, Ujwala; McCann, Robert S.; Beutter, Brent; Spirkovska, Lily

    2009-01-01

    Performance enhancements associated with selected forms of automation were quantified in a recent human-in-the-loop evaluation of two candidate operational concepts for fault management on next-generation spacecraft. The baseline concept, called Elsie, featured a full-suite of "soft" fault management interfaces. However, operators were forced to diagnose malfunctions with minimal assistance from the standalone caution and warning system. The other concept, called Besi, incorporated a more capable C&W system with an automated fault diagnosis capability. Results from analyses of participants' eye movements indicate that the greatest empirical benefit of the automation stemmed from eliminating the need for text processing on cluttered, text-rich displays.

  2. 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.

  3. 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

  4. 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; Cowlard, Adam J.; Rouvreau, Sebastien; Toth, Balazs; Jomaas, Grunde

    2012-01-01

    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 associated 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-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 structure. As a result, the prediction of the behaviour of fires in reduced gravity is at present not validated. To address this gap in knowledge, a collaborative international project, Spacecraft Fire Safety, has been established with its cornerstone being the development of an experiment (Fire Safety 1) to be conducted on an ISS resupply vehicle, such as the Automated Transfer Vehicle (ATV) or Orbital Cygnus after it leaves the ISS and before it enters the atmosphere. A computer modelling effort will complement the experimental effort. Although the experiment will need to meet rigorous safety requirements to ensure the carrier vehicle does not sustain damage, the absence of a crew removes the need for strict containment of combustion products. This will facilitate the possibility of examining fire behaviour on a scale that is relevant to spacecraft fire safety and will provide unique data for fire model validation. This unprecedented opportunity will expand the understanding of the fundamentals of fire behaviour in spacecraft. The experiment is being

  5. CMS Higgs Search in 2011 and 2012 data: candidate ZZ event (8 TeV) with two electrons and two muons: 3D perspective, r-phi and r-z views

    CERN Multimedia

    McCauley, T

    2012-01-01

    Event recorded with the CMS detector in 2012 at a proton-proton centre of mass energy of 8 TeV. The event shows characteristics expected from the decay of the SM Higgs boson to a pair of Z bosons, one of which subsequently decays to a pair of electrons (green lines and green towers) and the other Z decays to a pair of muons (red lines). The event could also be due to known standard model background processes.

  6. Amplitude Variability in gamma Dor and delta Scuti stars observed by the Kepler Spacecraft

    CERN Document Server

    Guzik, Joyce A; Bradley, Paul A; Jackiewicz, Jason

    2016-01-01

    The NASA Kepler spacecraft data revealed a large number of multimode nonradially pulsating gamma Dor and delta Sct variable star candidates. The high precision long time-series photometry makes it possible to study amplitude variations of the frequencies. We summarize recent literature on amplitude and frequency variations in pulsating variables. We are searching for amplitude variability in several dozen faint gamma Doradus or delta Scuti variable-star candidates observed as part of the Kepler Guest Observer program. We apply several methods, including a Matlab-script wavelet analysis developed by J. Jackiewicz, and the wavelet technique of the VSTAR software (http://www.aavso.org/vstar-overview). Here we show results for two stars, KIC 2167444 and KIC 2301163. We discuss the magnitude and timescale of the amplitude variations, and the presence or absence of correlations between amplitude variations for different frequencies of a given star. Amplitude variations may be detectable using Kepler data even for s...

  7. 76 FR 4896 - Call for Candidates

    Science.gov (United States)

    2011-01-27

    ... From the Federal Register Online via the Government Publishing Office FEDERAL ACCOUNTING STANDARDS ADVISORY BOARD Call for Candidates AGENCY: Federal Accounting Standards Advisory Board. ACTION: Notice... Federal Accounting Standards Advisory Board (FASAB) is currently seeking candidates (candidates must...

  8. 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.

  9. Introducing GV : The Spacecraft Geometry Visualizer

    Science.gov (United States)

    Throop, Henry B.; Stern, S. A.; Parker, J. W.; Gladstone, G. R.; Weaver, H. A.

    2009-12-01

    GV (Geometry Visualizer) is a web-based program for planning spacecraft observations. GV is the primary planning tool used by the New Horizons science team to plan the encounter with Pluto. GV creates accurate 3D images and movies showing the position of planets, satellites, and stars as seen from an observer on a spacecraft or other body. NAIF SPICE routines are used throughout for accurate calculations of all geometry. GV includes 3D geometry rendering of all planetary bodies, lon/lat grids, ground tracks, albedo maps, stellar magnitudes, types and positions from HD and Tycho-2 catalogs, and spacecraft FOVs. It generates still images, animations, and geometric data tables. GV is accessed through an easy-to-use and flexible web interface. The web-based interface allows for uniform use from any computer and assures that all users are accessing up-to-date versions of the code and kernel libraries. Compared with existing planning tools, GV is often simpler, faster, lower-cost, and more flexible. GV was developed at SwRI to support the New Horizons mission to Pluto. It has been subsequently expanded to support multiple other missions in flight or under development, including Cassini, Messenger, Rosetta, LRO, and Juno. The system can be used to plan Earth-based observations such as occultations to high precision, and was used by the public to help plan 'Kodak Moment' observations of the Pluto system from New Horizons. Potential users of GV may contact the author for more information. Development of GV has been funded by the New Horizons, Rosetta, and LRO missions.

  10. High Energy Failure Containment for Spacecraft

    Science.gov (United States)

    Pektas, Pete; Baker, Christopher

    2011-01-01

    Objective: The objective of this paper will be to investigate advancements and any commonality between spacecraft debris containment and the improvements being made in ballistic protection. Scope: This paper will focus on cross application of protection devices and methods, and how they relate to protecting humans from failures in spacecraft. The potential gain is to reduce the risk associated with hardware failure, while decreasing the weight and size of energy containment methods currently being used by the government and commercial industry. Method of Approach: This paper will examine testing that has already been accomplished in regards to the failure of high energy rotating hardware and compare it to advancements in ballistic protection. Examples are: DOT research and testing of turbine containment as documented in DOT/FAA/AR-96/110, DOT/FAA/AR-97/82, DOT/FAA/AR-98/22. It will also look at work accomplished by companies such as ApNano and IBD Deisenroth in the development of nano ceramics and nanometric steels. Other forms of energy absorbent materials and composites will also be considered and discussed. New Advances in State of the Art: There have been numerous advances in technology in regards to high energy debris containment and in the similar field of ballistic protection. This paper will discuss methods such as using impregnated or dry Kevlar, ceramic, and nano-technology which have been successfully tested but are yet to be utilized in spacecraft. Reports on tungsten disulfide nanotubes claim that they are 4-5 times stronger than steel and reports vary about the magnitude increase over Kevlar, but it appears to be somewhere in the range of 2-6 times stronger. This technology could also have applications in the protection of pressure vessels, motor housings, and hydraulic component failures.

  11. 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.

  12. Five Kepler Target Stars That Show Multiple Transiting Exoplanet Candidates

    Science.gov (United States)

    Steffen, Jason H.; Batalha, Natalie M.; Borucki, William J.; Buchhave, Lars A.; Caldwell, Douglas A.; Cochran, William D.; Endl, Michael; Fabrycky, Daniel C.; Fressin, François; Ford, Eric B.; Fortney, Jonathan J.; Haas, Michael J.; Holman, Matthew J.; Howell, Steve B.; Isaacson, Howard; Jenkins, Jon M.; Koch, David; Latham, David W.; Lissauer, Jack J.; Moorhead, Althea V.; Morehead, Robert C.; Marcy, Geoffrey; MacQueen, Phillip J.; Quinn, Samuel N.; Ragozzine, Darin; Rowe, Jason F.; Sasselov, Dimitar D.; Seager, Sara; Torres, Guillermo; Welsh, William F.

    2010-12-01

    We present and discuss five candidate exoplanetary systems identified with the Kepler spacecraft. These five systems show transits from multiple exoplanet candidates. Should these objects prove to be planetary in nature, then these five systems open new opportunities for the field of exoplanets and provide new insights into the formation and dynamical evolution of planetary systems. We discuss the methods used to identify multiple transiting objects from the Kepler photometry as well as the false-positive rejection methods that have been applied to these data. One system shows transits from three distinct objects while the remaining four systems show transits from two objects. Three systems have planet candidates that are near mean motion commensurabilities—two near 2:1 and one just outside 5:2. We discuss the implications that multi-transiting systems have on the distribution of orbital inclinations in planetary systems, and hence their dynamical histories, as well as their likely masses and chemical compositions. A Monte Carlo study indicates that, with additional data, most of these systems should exhibit detectable transit timing variations (TTVs) due to gravitational interactions, though none are apparent in these data. We also discuss new challenges that arise in TTV analyses due to the presence of more than two planets in a system.

  13. Five Kepler target stars that show multiple transiting exoplanet candidates

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Jason H.; /Fermilab; Batalha, Natalie M.; /San Jose State U.; Borucki, William J.; /NASA, Ames; Buchhave, Lars A.; /Harvard-Smithsonian Ctr. Astrophys. /Bohr Inst.; Caldwell, Douglas A.; /NASA, Ames /SETI Inst., Mtn. View; Cochran, William D.; /Texas U.; Endl, Michael; /Texas U.; Fabrycky, Daniel C.; /Harvard-Smithsonian Ctr. Astrophys.; Fressin, Francois; /Harvard-Smithsonian Ctr. Astrophys.; Ford, Eric B.; /Florida U.; Fortney, Jonathan J.; /UC, Santa Cruz, Phys. Dept. /NASA, Ames

    2010-06-01

    We present and discuss five candidate exoplanetary systems identified with the Kepler spacecraft. These five systems show transits from multiple exoplanet candidates. Should these objects prove to be planetary in nature, then these five systems open new opportunities for the field of exoplanets and provide new insights into the formation and dynamical evolution of planetary systems. We discuss the methods used to identify multiple transiting objects from the Kepler photometry as well as the false-positive rejection methods that have been applied to these data. One system shows transits from three distinct objects while the remaining four systems show transits from two objects. Three systems have planet candidates that are near mean motion commensurabilities - two near 2:1 and one just outside 5:2. We discuss the implications that multitransiting systems have on the distribution of orbital inclinations in planetary systems, and hence their dynamical histories; as well as their likely masses and chemical compositions. A Monte Carlo study indicates that, with additional data, most of these systems should exhibit detectable transit timing variations (TTV) due to gravitational interactions - though none are apparent in these data. We also discuss new challenges that arise in TTV analyses due to the presence of more than two planets in a system.

  14. MEMS device for spacecraft thermal control applications

    Science.gov (United States)

    Swanson, Theordore D. (Inventor)

    2003-01-01

    A micro-electromechanical device that comprises miniaturized mechanical louvers, referred to as Micro Electro-Mechanical Systems (MEMS) louvers are employed to achieve a thermal control function for spacecraft and instruments. The MEMS louvers are another form of a variable emittance control coating and employ micro-electromechanical technology. In a function similar to traditional, macroscopic thermal louvers, the MEMS louvers of the present invention change the emissivity of a surface. With the MEMS louvers, as with the traditional macroscopic louvers, a mechanical vane or window is opened and closed to allow an alterable radiative view to space.

  15. Metal band drives in spacecraft mechanisms

    Science.gov (United States)

    Maus, Daryl

    1993-05-01

    Transmitting and changing the characteristics of force and stroke is a requirement in nearly all mechanisms. Examples include changing linear to rotary motion, providing a 90 deg change in direction, and amplifying stroke or force. Requirements for size, weight, efficiency and reliability create unique problems in spacecraft mechanisms. Flexible metal band and cam drive systems provide powerful solutions to these problems. Band drives, rack and pinion gears, and bell cranks are compared for effectiveness. Band drive issues are discussed including materials, bend radius, fabrication, attachment and reliability. Numerous mechanisms are shown which illustrate practical applications of band drives.

  16. Status of the JWST sunshield and spacecraft

    Science.gov (United States)

    Arenberg, J.; Flynn, J.; Cohen, A.; Lynch, R.; Cooper, J.

    2016-07-01

    This paper reports on the development, manufacture and integration of the James Webb Space Telescope's sunshield and spacecraft. Both of these JWST elements have completed design and development testing. This paper will review basic architecture and roles of these systems. Also to be presented is the current state of manufacture, assembly integration and test. This paper will conclude with a look at the road ahead for each subsystem prior to integration with the integrated telescope and instrument elements at Northrop Grumman's Space Park facility in late 2017.

  17. Fault Detection and Isolation for Spacecraft

    DEFF Research Database (Denmark)

    Jensen, Hans-Christian Becker; Wisniewski, Rafal

    2002-01-01

    This article realizes nonlinear Fault Detection and Isolation for actuators, given there is no measurement of the states in the actuators. The Fault Detection and Isolation of the actuators is instead based on angular velocity measurement of the spacecraft and knowledge about the dynamics of the...... satellite. The algorithms presented in this paper are based on a geometric approach to achieve nonlinear Fault Detection and Isolation. The proposed algorithms are tested in a simulation study and the pros and cons of the algorithms are discussed....

  18. Loading operations for spacecraft propulsion subsystems

    Science.gov (United States)

    Purohit, G. P.; Nordeng, H. O.; Ellison, J. R.

    1992-07-01

    This paper provides a broad overview of loading operations for pressurized blowdown monopropellant and pressure regulated integral bipropellant propulsion subsystems used in geosynchronous communication satellites. Propellant chemical composition, cleanliness, processing, and handling requirements are addressed. Ground servicing equipment (GSE) and propellant transfer procedures for the various loading configurations are discussed. Effects of helium solubility and helium saturation levels in both GSE carts and propellant tanks are examined. Predicted equilibrium pressures for actual postload tank pressures are compared against extensive loading data on Hughes bipropellant spacecraft. Helium tank pressurization and manifold pressurization practices are described. Propellant loading facility requirements and safety requirements are discussed.

  19. Effects of Spacecraft Landings on the Moon

    Science.gov (United States)

    Metzger, Philip T.; Lane, John E.

    2013-01-01

    The rocket exhaust of spacecraft landing on the Moon causes a number of observable effects that need to be quantified, including: disturbance of the regolith and volatiles at the landing site; damage to surrounding hardware such as the historic Apollo sites through the impingement of high-velocity ejecta; and levitation of dust after engine cutoff through as-yet unconfirmed mechanisms. While often harmful, these effects also beneficially provide insight into lunar geology and physics. Some of the research results from the past 10 years is summarized and reviewed here.

  20. Large Scale Experiments on Spacecraft Fire Safety

    DEFF Research Database (Denmark)

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

    2012-01-01

    to ensure the carrier vehicle does not sustain damage, the absence of a crew removes the need for strict containment of combustion products. This will facilitate the possibility of examin-ing fire behaviour on a scale that is relevant to spacecraft fire safety and will provide unique data for fire model......) to be conducted on an ISS resupply vehicle, such as the Automated Transfer Vehicle (ATV) or Orbital Cygnus after it leaves the ISS and before it enters the atmosphere. A computer modelling effort will complement the experimental effort. Although the experiment will need to meet rigorous safety requirements...

  1. Impulsive orbit control for spacecraft around asteroid

    Institute of Scientific and Technical Information of China (English)

    崔祜涛; 崔平远; 栾恩杰

    2003-01-01

    An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time.Then, the feedback control law based on Gauss' s perturbation equations of motion is given. And the impulse control for targeting from the higher circulation orbit to the specified periapsis is developed. Finally, the numerical simulation is performed and the simulation results show that the presented impulse control law is effective.

  2. Aero-Assisted Spacecraft Missions Using Hypersonic Waverider Aeroshells

    Science.gov (United States)

    Knittel, Jeremy

    This work examines the use of high-lift, low drag vehicles which perform orbital transfers within a planet's atmosphere to reduce propulsive requirements. For the foreseeable future, spacecraft mission design will include the objective of limiting the mass of fuel required. One means of accomplishing this is using aerodynamics as a supplemental force, with what is termed an aero-assist maneuver. Further, the use of a lifting body enables a mission designer to explore candidate trajectory types wholly unavailable to non-lifting analogs. Examples include missions to outer planets by way of an aero-gravity assist, aero-assisted plane change, aero-capture, and steady atmospheric periapsis probing missions. Engineering level models are created in order to simulate both atmospheric and extra-atmospheric space flight. Each mission is parameterized using discrete variables which control multiple areas of design. This work combines the areas of hypersonic aerodynamics, re-entry aerothermodynamics, spacecraft orbital mechanics, and vehicle shape optimization. In particular, emphasis is given to the parametric design of vehicles known as "waveriders" which are inversely designed from known shock flowfields. An entirely novel means of generating a class of waveriders known as "starbodies" is presented. A complete analysis is performed of asymmetric starbody forms and compared to a better understood parameterization, "osculating cone" waveriders. This analysis includes characterization of stability behavior, a critical discipline within hypersonic flight. It is shown that asymmetric starbodies have significant stability improvement with only a 10% reduction in the lift-to-drag ratio. By combining the optimization of both the shape of the vehicle and the trajectory it flies, much is learned about the benefit that can be expected from lifting aero-assist missions. While previous studies have conceptually proven the viability, this work provides thorough quantification of the

  3. Thermal Design, Test and Analysis of PharmaSat, a Small Class D Spacecraft with a Biological Experiment

    Science.gov (United States)

    Diaz-Aguado, Millan F.; VanOutryve, Cassandra; Ghassemiah, Shakib; Beasley, Christopher; Schooley, Aaron

    2009-01-01

    Small spacecraft have been increasing in popularity because of their low cost, short turnaround and relative efficiency. In the past, small spacecraft have been primarily used for technology demonstrations, but advances in technology have made the miniaturization of space science possible [1,2]. PharmaSat is a low cost, small three cube size spacecraft, with a biological experiment on board, built at NASA (National Aeronautics and Space Administration) Ames Research Center. The thermal design of small spacecraft presents challenges as their smaller surface areas translate into power and thermal constraints. The spacecraft is thermally designed to run colder in the Low Earth Orbit space environment, and heated to reach the temperatures required by the science payload. The limited power supply obtained from the solar panels on small surfaces creates a constraint in the power used to heat the payload to required temperatures. The pressurized payload is isolated with low thermally conductance paths from the large ambient temperature changes. The thermal design consists of different optical properties of section surfaces, Multi Layer Insulation (MLI), low thermal conductance materials, flexible heaters and thermal spreaders. The payload temperature is controlled with temperature sensors and flexible heaters. Finite Element Analysis (FEA) and testing were used to aid the thermal design of the spacecraft. Various tests were conducted to verify the thermal design. An infrared imager was used on the electronic boards to find large heat sources and eliminate any possible temperature runaways. The spacecraft was tested in a thermal vacuum chamber to optimize the thermal and power analysis and qualify the thermal design of the spacecraft for the mission.

  4. Multi-spacecraft observations of quasiperiodic emissions

    Science.gov (United States)

    Nemec, Frantisek; Pickett, Jolene S.; Hospodarsky, George; Santolik, Ondrej; Bezdekova, Barbora; Hayosh, Mykhaylo; Parrot, Michel; Kurth, William; Kletzing, Craig

    2016-04-01

    Whistler mode electromagnetic waves observed in the inner magnetosphere at frequencies of a few kilohertz sometimes exhibit a nearly periodic modulation of the wave intensity. The modulation periods may range from several tens of seconds up to a few minutes, and such emissions are usually called quasiperiodic (QP) emissions. The origin of these events is still unclear, but it seems that their generation might be related to compressional ULF magnetic field pulsations which periodically modulate resonance conditions in the source region. From an observational point of view, single-point measurements are quite insufficient, as they do not allow us to distinguish between spatial and temporal variations of the emissions. Multipoint observations of these events are, on the other hand, rather rare. We present several QP wave events observed simultaneously by several different spacecraft (Cluster, Van Allen Probes, THEMIS, DEMETER). We demonstrate that although the quasiperiodic modulation is observed over a huge spatial region, individual spacecraft do not see the QP elements at exactly the same times. Moreover, when an event is observed simultaneously on the dawnside and on the duskside, the modulation period observed on the duskside is about twice larger than the modulation period observed on the dawnside. We present a qualitative explanation of these phenomena.

  5. High temperature thruster technology for spacecraft propulsion

    Science.gov (United States)

    Schneider, Steven J.

    A technology program has been underway since 1985 to develop high temperature oxidation-resistant thrusters for spacecraft applications. The successful development of this technology will provide the basis for the design of higher performance satellite engines with reduced plume contamination. Alternatively, this technology program will provide a material with high thermal margin to operate at conventional temperatures and provide increased life for refuelable or reusable spacecraft. The new chamber material consists of a rhenium substrate coated with iridium for oxidation protection. This material increases the operating temperature of thrusters to 2200°C, a significant increase over the 1400°C of the silicide-coated niobium chambers currently used. Stationkeeping class 22 N engines fabricated from iridium-coated rhenium have demonstrated steady state specific impulses 20 to 25 seconds higher than niobium chambers. Ir-Re apogee class 440 N engines are expected to deliver an additional 10 to 15 seconds. These improved performances are obtained by reducing or eliminating the fuel film cooling requirements in the combustion chamber while operating at the same overall mixture ratio as conventional engines. The program is attempting to envelope flight qualification requirements to reduce the potential risks and costs of flight qualification programs.

  6. 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.

  7. Spacecraft Angular Rates Estimation with Gyrowheel Based on Extended High Gain Observer.

    Science.gov (United States)

    Liu, Xiaokun; Yao, Yu; Ma, Kemao; Zhao, Hui; He, Fenghua

    2016-04-14

    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.

  8. Spacecraft Angular Rates Estimation with Gyrowheel Based on Extended High Gain Observer.

    Science.gov (United States)

    Liu, Xiaokun; Yao, Yu; Ma, Kemao; Zhao, Hui; He, Fenghua

    2016-01-01

    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. PMID:27089347

  9. 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.

  10. Empathy Development in Teacher Candidates

    Science.gov (United States)

    Boyer, Wanda

    2010-01-01

    Using a grounded theory research design, the author examined 180 reflective essays of teacher candidates who participated in a "Learning Process Project," in which they were asked to synthesize and document their discoveries about the learning process over the course of a completely new learning experience as naive learners. This study explored…

  11. Candidate gene prioritization with Endeavour.

    Science.gov (United States)

    Tranchevent, Léon-Charles; Ardeshirdavani, Amin; ElShal, Sarah; Alcaide, Daniel; Aerts, Jan; Auboeuf, Didier; Moreau, Yves

    2016-07-01

    Genomic studies and high-throughput experiments often produce large lists of candidate genes among which only a small fraction are truly relevant to the disease, phenotype or biological process of interest. Gene prioritization tackles this problem by ranking candidate genes by profiling candidates across multiple genomic data sources and integrating this heterogeneous information into a global ranking. We describe an extended version of our gene prioritization method, Endeavour, now available for six species and integrating 75 data sources. The performance (Area Under the Curve) of Endeavour on cross-validation benchmarks using 'gold standard' gene sets varies from 88% (for human phenotypes) to 95% (for worm gene function). In addition, we have also validated our approach using a time-stamped benchmark derived from the Human Phenotype Ontology, which provides a setting close to prospective validation. With this benchmark, using 3854 novel gene-phenotype associations, we observe a performance of 82%. Altogether, our results indicate that this extended version of Endeavour efficiently prioritizes candidate genes. The Endeavour web server is freely available at https://endeavour.esat.kuleuven.be/. PMID:27131783

  12. Candidate Prediction Models and Methods

    DEFF Research Database (Denmark)

    Nielsen, Henrik Aalborg; Nielsen, Torben Skov; Madsen, Henrik;

    2005-01-01

    This document lists candidate prediction models for Work Package 3 (WP3) of the PSO-project called ``Intelligent wind power prediction systems'' (FU4101). The main focus is on the models transforming numerical weather predictions into predictions of power production. The document also outlines the...

  13. Candidate cave entrances on Mars

    Science.gov (United States)

    Cushing, Glen E.

    2012-01-01

    This paper presents newly discovered candidate cave entrances into Martian near-surface lava tubes, volcano-tectonic fracture systems, and pit craters and describes their characteristics and exploration possibilities. These candidates are all collapse features that occur either intermittently along laterally continuous trench-like depressions or in the floors of sheer-walled atypical pit craters. As viewed from orbit, locations of most candidates are visibly consistent with known terrestrial features such as tube-fed lava flows, volcano-tectonic fractures, and pit craters, each of which forms by mechanisms that can produce caves. Although we cannot determine subsurface extents of the Martian features discussed here, some may continue unimpeded for many kilometers if terrestrial examples are indeed analogous. The features presented here were identified in images acquired by the Mars Odyssey's Thermal Emission Imaging System visible-wavelength camera, and by the Mars Reconnaissance Orbiter's Context Camera. Select candidates have since been targeted by the High-Resolution Imaging Science Experiment. Martian caves are promising potential sites for future human habitation and astrobiology investigations; understanding their characteristics is critical for long-term mission planning and for developing the necessary exploration technologies.

  14. Study on Space Debris and Impact Effect on Spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Huang Hai; Jia Guanghui; Dong Yunfeng [School of Astronautics, Beihang University (BUAA), Xueyuan Road No.37, Beijing 100083 (China)

    2007-04-15

    Space debris is increasingly concerned by aerospace engineers and scientists. The evolution of an orbital debris cloud, the collision probability between of debris and a spacecraft, and the damage evaluation of spacecraft when impacted by space debris are studied in this work. A hypervelocity impact model for honeycomb panel is proposed. Under considering secondary debris, the survivability of spacecraft impacted by space debris is finally investigated.

  15. A generalized modal shock spectra method for spacecraft loads analysis

    Science.gov (United States)

    Trubert, M.; Salama, M.

    1979-01-01

    Unlike the traditional shock spectra approach, the generalization presented in this paper permits elastic interaction between the spacecraft and launch vehicle in order 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 in order 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.

  16. Concurrent engineering: Spacecraft and mission operations system design

    Science.gov (United States)

    Landshof, J. A.; Harvey, R. J.; Marshall, M. H.

    1994-01-01

    Despite our awareness of the mission design process, spacecraft historically have been designed and developed by one team and then turned over as a system to the Mission Operations organization to operate on-orbit. By applying concurrent engineering techniques and envisioning operability as an essential characteristic of spacecraft design, tradeoffs can be made in the overall mission design to minimize mission lifetime cost. Lessons learned from previous spacecraft missions will be described, as well as the implementation of concurrent mission operations and spacecraft engineering for the Near Earth Asteroid Rendezvous (NEAR) program.

  17. Planetary spacecraft - SEPS interface design. [Solar Electric Propulsion System

    Science.gov (United States)

    Pless, L. C.

    1980-01-01

    The interactions between a spacecraft which would rendezvous with the comet Tempel II, the stage, and the mission design are summarized along with solar electric propulsion system design issues. Attention is given to data communication, the spacecraft pointing control system, spacecraft power, plasma interactions, the release of a probe to study the comet Halley, and thruster usage. It was concluded that for a planetary mission design using a low-thrust stage, the control of the mission should reside in the payload spacecraft and that the power should be provided by the stage; the NASA standard 28 VDC bus is recommended.

  18. The communications payload of the MSAT spacecraft

    Science.gov (United States)

    Belanger, R.; Moody, H. J.; Hatzigeorgiou, S.; Turgeon, G.; Voulelikas, G.

    To be launched in 1994, the MSAT satellites will provide coverage of Canada, continental United States, Alaska, Hawaii, Puerto Rico and Mexico. The mobile users will be linked to the spacecraft by 6 high gain beams providing over 57 dBW Aggregate Effective Isotropic Radiated Power at L-band. To achieve this, two major technologies are being pushed to new limits. First, the MSAT antennas use very large deployable offset mesh reflectors. These reflectors combined with the fully integrated beam forming network provide the high directivity beams necessary for the L-band coverage. Second, MSAT uses high efficiency SSP As with 35 watts at better than 16 dB noise power ratio. By combining these SSP As in a hybrid matrix amplifier system, nearly 500 watts of RF power is delivered to the L-band antenna. With this amount of power, each MSAT satellite can service up to 400,000 subscribers.

  19. Electrochromic emissivity modulator for spacecraft thermal management

    Energy Technology Data Exchange (ETDEWEB)

    Demiryont, Hulya; Moorehead, David [Eclipse Energy Systems, Inc., 2345 Anvil Street North, St. Petersburg, FL 33710 (United States)

    2009-12-15

    A novel electrochromic device (ECD) working in mid- to long-wave infrared (IR) region is presented, comprising of a solid-state monolithic thin film system for adjusting heat rejection/receiving levels on attached surfaces. The system is an electrically controllable active emissivity modulator. EclipseVED trademark, variable-emissivity ECD, is designed for satellite and spacecraft thermal control, using an active ECD system for long-wave infrared (LWIR) modulation and a passive cold mirror for solar rejection. Emissivity modulation of the system is 0.8 for 7-12 {mu}m region while average solar rejection is 80% in the vis-NIR region. Device properties and initial space test results are also presented. (author)

  20. A Microwave Thruster for Spacecraft Propulsion

    Energy Technology Data Exchange (ETDEWEB)

    Chiravalle, Vincent P [Los Alamos National Laboratory

    2012-07-23

    This presentation describes how a microwave thruster can be used for spacecraft propulsion. A microwave thruster is part of a larger class of electric propulsion devices that have higher specific impulse and lower thrust than conventional chemical rocket engines. Examples of electric propulsion devices are given in this presentation and it is shown how these devices have been used to accomplish two recent space missions. The microwave thruster is then described and it is explained how the thrust and specific impulse of the thruster can be measured. Calculations of the gas temperature and plasma properties in the microwave thruster are discussed. In addition a potential mission for the microwave thruster involving the orbit raising of a space station is explored.

  1. A pulsed cathodic arc spacecraft propulsion system

    Science.gov (United States)

    Neumann, P. R. C.; Bilek, M. M. M.; Tarrant, R. N.; McKenzie, D. R.

    2009-11-01

    We investigate the use of a centre-triggered cathodic arc as a spacecraft propulsion system that uses an inert solid as a source of plasma. The cathodic vacuum arc produces almost fully ionized plasma with a high exhaust velocity (>104 m s-1), giving a specific impulse competitive with other plasma or ion thrusters. A centre trigger design is employed that enables efficient use of cathode material and a high pulse-to-pulse repeatability. We compare three anode geometries, two pulse current profiles and two pulse durations for their effects on impulse generation, energy and cathode material usage efficiency. Impulse measurement is achieved through the use of a free-swinging pendulum target constructed from a polymer material. Measurements show that impulse is accurately controlled by varying cathode current. The cylindrical anode gave the highest energy efficiency. Cathode usage is optimized by choosing a sawtooth current profile. There is no requirement for an exhaust charge neutralization system.

  2. Optimal configuration of dual-spacecraft radio occultation observation for future lunar ionosphere exploration

    Science.gov (United States)

    Kikuchi, Fuyuhiko; Matsumoto, Koji

    2014-05-01

    The lunar ionosphere is one of the remaining mysteries of the Moon. The lunar ionosphere was found by stellar radio occultation observations (Elsmore, 1957) and radio occultation observations of spacecraft, such as Luna 19, Luna 20, and SELENE (Vasilyev et al., 1974; Vyshlov et al., 1976; Imamura et al., 2012). However, the existence of the lunar ionosphere is still debated. The estimated electron densities of several hundreds to 1000 cm-3 are much larger than a theoretical estimate (Daily et al., 1977). Three different theories have been proposed to explain the existence of the lunar ionosphere. One is increase in the density of the neutral particle near the terminator, which is supply source of electrons (Daily et al., 1977). Second is existence of remnant magnetic fields which prevent the solar wind from stripping electrons of the lunar ionosphere (Savich 1976). Third is updraft of charged dust grains which are accompanied by electrons (Stubbs et al., 2011). The cause of the lunar ionosphere remains an open question because the quality and quantity of the present data are inadequate. Principal factor is the terrestrial ionosphere. The amplitude of fluctuation of total electron content (TEC) of the terrestrial ionosphere is similar to or larger than the expected TEC of the lunar ionosphere. The cause of the lunar ionosphere cannot be elucidated without removal of the terrestrial ionosphere. A dual-spacecraft radio occultation technique is one of the effective methods to remove the effect of the terrestrial ionosphere. By observing a target and a reference spacecraft simultaneously, the fluctuation of the terrestrial ionosphere which is common in two propagation paths can be canceled out. The dual-spacecraft technique has been used in the radio occultation experiment on SELENE mission (Ando et al., 2012). Although the enhancement of the electric density caused by the lunar ionosphere was detected, the number of successful observations was severely restricted

  3. New potential AChE inhibitor candidates.

    Science.gov (United States)

    de Paula, A A N; Martins, J B L; dos Santos, M L; Nascente, L de C; Romeiro, L A S; Areas, T F M A; Vieira, K S T; Gambôa, N F; Castro, N G; Gargano, R

    2009-09-01

    We have theoretically studied new potential candidates of acetylcholinesterase (AChE) inhibitors designed from cardanol, a non-isoprenoid phenolic lipid of cashew Anacardium occidentale nut-shell liquid. The electronic structure calculations of fifteen molecule derivatives from cardanol were performed using B3LYP level with 6-31G, 6-31G(d), and 6-311+G(2d,p) basis functions. For this study we used the following groups: methyl, acetyl, N,N-dimethylcarbamoyl, N,N-dimethylamine, N,N-diethylamine, piperidine, pyrrolidine, and N,N-methylbenzylamine. Among the proposed compounds we identified that the structures with substitution by N,N-dimethycarbamoyl, N,N-dimethylamine, and pyrrolidine groups were better correlated to rivastigmine, and represent possible AChE inhibitors against Alzheimer disease. PMID:19446931

  4. Halopentacenes: Promising Candidates for Organic Semiconductors

    Institute of Scientific and Technical Information of China (English)

    DU Gong-He; REN Zhao-Yu; GUO Ping; ZHENG Ji-Ming

    2009-01-01

    We introduce polar substituents such as F, Cl, Br into pentacene to enhance the dissolubility in common organic solvents while retaining the high charge-carrier mobilities of pentacene. Geometric structures, dipole moments,frontier molecule orbits, ionization potentials and electron affinities, as well as reorganization energies of those molecules, and of pentacene for comparison, are successively calculated by density functional theory. The results indicate that halopentacenes have rather small reorganization energies (< 0.2 eV), and when the substituents are in position 2 or positions 2 and 9, they are polarity molecules. Thus we conjecture that they can easily be dissolved in common organic solvents, and are promising candidates for organic semiconductors.

  5. Double Cusp Observed By The Cluster Spacecraft

    Science.gov (United States)

    Escoubet, C. P.; Bosqued, J. M.; Berchem, J.; Anderson, P. C.; Fehringer, M.; Laakso, H.; Reme, H.

    The polar cusp is characterised by a direct entry of solar wind plasma into the magne- tosphere. Depending on the orientation of the interplanetary magnetic field (IMF), Bz positive or negative, the precipitation of the ions in the cusp presents a dispersion in energy directed poleward or equatorward. In addition the polar cusp moves in latitude according to the IMF, from about 75 deg. ILAT for Bz negative to about 82 deg. ILAT for Bz positive. The Cluster spacecraft are crossing the mid-altitude polar cusp, in a "string of pearl" configuration, and are therefore the ideal tool to study the motion and evolution of the cusp on time scale of a few minutes up to 45 min. On 30 August 2001, the four Cluster spacecraft crossed the mid-altitude polar cusp (4-6 Re) around 12.5 H local time with SC4 entering the cusp at 1532 UT, SC2 following 1.5 min later, SC1, 3 min later and finally SC3, 45 min later. SC4 and SC1 observed a typical poleward dispersion associated with Bz negative. SC3 observed first the same disper- sion starting at about 74 deg. ILAT, however at 81 deg. ILAT a second dispersion was observed. The IMF was southward during the dispersion and became slightly positive during the second dispersion. Two hypothesis can be proposed, a fast motion of the cusp poleward during the SC3 crossing or a double injection in the cusp. Preliminary analysis of DMSP satellites, although not exactly in the same sector, indicates that the cusp moved poleward around that time. Cluster observations will be compared with the results from a global MHD simulation model to investigate the geometry of the reconnection between the IMF and the Earth magnetic field.

  6. Generalized Analysis Tools for Multi-Spacecraft Missions

    Science.gov (United States)

    Chanteur, G. M.

    2011-12-01

    Analysis tools for multi-spacecraft missions like CLUSTER or MMS have been designed since the end of the 90's to estimate gradients of fields or to characterize discontinuities crossed by a cluster of spacecraft. Different approaches have been presented and discussed in the book "Analysis Methods for Multi-Spacecraft Data" published as Scientific Report 001 of the International Space Science Institute in Bern, Switzerland (G. Paschmann and P. Daly Eds., 1998). On one hand the approach using methods of least squares has the advantage to apply to any number of spacecraft [1] but is not convenient to perform analytical computation especially when considering the error analysis. On the other hand the barycentric approach is powerful as it provides simple analytical formulas involving the reciprocal vectors of the tetrahedron [2] but appears limited to clusters of four spacecraft. Moreover the barycentric approach allows to derive theoretical formulas for errors affecting the estimators built from the reciprocal vectors [2,3,4]. Following a first generalization of reciprocal vectors proposed by Vogt et al [4] and despite the present lack of projects with more than four spacecraft we present generalized reciprocal vectors for a cluster made of any number of spacecraft : each spacecraft is given a positive or nul weight. The non-coplanarity of at least four spacecraft with strictly positive weights is a necessary and sufficient condition for this analysis to be enabled. Weights given to spacecraft allow to minimize the influence of some spacecraft if its location or the quality of its data are not appropriate, or simply to extract subsets of spacecraft from the cluster. Estimators presented in [2] are generalized within this new frame except for the error analysis which is still under investigation. References [1] Harvey, C. C.: Spatial Gradients and the Volumetric Tensor, in: Analysis Methods for Multi-Spacecraft Data, G. Paschmann and P. Daly (eds.), pp. 307-322, ISSI

  7. IAEA Director General candidates announced

    International Nuclear Information System (INIS)

    Full text: The IAEA today confirms receipt of the nomination of five candidates for Director General of the IAEA. Nominations of the following individuals have been received by the Chairperson of the IAEA Board of Governors, Ms. Taous Feroukhi: Mr. Jean-Pol Poncelet of Belgium; Mr. Yukiya Amano of Japan; Mr. Ernest Petric of Slovenia; Mr. Abdul Samad Minty of South Africa; and Mr. Luis Echavarri of Spain. The five candidates were nominated in line with a process approved by the Board in October 2008. IAEA Director General Mohamed ElBaradei's term of office expires on 30 November 2009. He has served as Director General since 1997 and has stated that he is not available for a fourth term of office. (IAEA)

  8. Enthalpy screen of drug candidates.

    Science.gov (United States)

    Schön, Arne; Freire, Ernesto

    2016-11-15

    The enthalpic and entropic contributions to the binding affinity of drug candidates have been acknowledged to be important determinants of the quality of a drug molecule. These quantities, usually summarized in the thermodynamic signature, provide a rapid assessment of the forces that drive the binding of a ligand. Having access to the thermodynamic signature in the early stages of the drug discovery process will provide critical information towards the selection of the best drug candidates for development. In this paper, the Enthalpy Screen technique is presented. The enthalpy screen allows fast and accurate determination of the binding enthalpy for hundreds of ligands. As such, it appears to be ideally suited to aid in the ranking of the hundreds of hits that are usually identified after standard high throughput screening.

  9. Leishmaniasis: vaccine candidates and perspectives.

    Science.gov (United States)

    Singh, Bhawana; Sundar, Shyam

    2012-06-01

    Leishmania is a protozoan parasite and a causative agent of the various clinical forms of leishmaniasis. High cost, resistance and toxic side effects of traditional drugs entail identification and development of therapeutic alternatives. The sound understanding of parasite biology is key for identifying novel drug targets, that can induce the cell mediated immunity (mainly CD4+ and CD8+ IFN-gamma mediated responses) polarized towards a Th1 response. These aspects are important in designing a new vaccine along with the consideration of the candidates with respect to their ability to raise memory response in order to improve the vaccine performance. This review is an effort to identify molecules according to their homology with the host and their ability to be used as potent vaccine candidates.

  10. Estimation of the Probability of Radiation Failures and Single Particle Upsets of Integrated Microcircuits onboard the Fobos-Grunt Spacecraft

    Science.gov (United States)

    Kuznetsov, N. V.; Popov, V. D.; Khamidullina, N. M.

    2005-05-01

    When designing the radio-electronic equipment for long-term operation in a space environment, one of the most important problems is a correct estimation of radiation stability of its electric and radio components (ERC) against radiation-stimulated doze failures and one-particle effects (upsets). These problems are solved in this paper for the integrated microcircuits (IMC) of various types that are to be installed onboard the Fobos-Grunt spacecraft designed at the Federal State Unitary Enterprise “Lavochkin Research and Production Association.” The launching of this spacecraft is planned for 2009.

  11. Assessment of potential solder candidates for high temperature applications

    DEFF Research Database (Denmark)

    of the package with different solders of different melting temperatures. High Pb containing alloys where the lead levels can be above 85% by weight, is one of the solders currently being used in this technology. Responding to market pressure i.e. need for green electronic products there is now an increasing...... complicates the corrosion problems. Although the cost of corrosion in the electronic sector could not be estimated, it has been suggested that a significant part of all electronic system failures are caused by corrosion. Thus, the determined potential solder candidates were classified based on its property...

  12. Gas flow analysis during thermal vacuum test of a spacecraft. [self contamination of IMP spacecraft

    Science.gov (United States)

    Scialdone, J. J.

    1974-01-01

    The self-contamination of the IMP-H spacecraft, while it was undergoing thermal and solar vacuum tests, has been investigated in conjunction with the outgassing evaluation and detection of molecular flow anomalies occurring in the test chamber. The pressures indicated by two tubulated ionization gauges were used to calculate flow kinetics in the vacuum chamber. The fluxes of emitted molecules and chamber wall reflected molecules were monitored during the entire test. Representative equations and graphs are presented. Test results indicate that from 3 to 9 of every 100 emitted molecules returned to the spacecraft surface; that self-contamination by noncondensable gases was more severe than that by condensable gases; and that outgassing of the spacecraft was approximately 1.18 x 0.01 g/s after 10 hours and 1.18 x 0.001 after 90 hours of vacuum exposure. Testing deficiencies have been identified, and the type and location of instruments required to measure the outgassing, the degree of contamination, and return flow are discussed.

  13. Analytical Investigation of Pumped Fluid Loop Radiators for Orion Spacecraft

    Science.gov (United States)

    Reavis, Gretchen

    2007-01-01

    This viewgraph presentation reviews the history of pumped fluid loop radiators used in Apollo spacecraft, and the problems and challenges for using them in the Orion Spacecraft. Included in this presentation are the issues of Flow stagnation, flow stability, for single panels and multi-panels.

  14. Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

    International Nuclear Information System (INIS)

    Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth's magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft's orientation. We assume that the spacecraft is moving in the Earth's magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole. A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio (α*). Stable orbits are identified for various values of α*. The main parameters for stabilization of the spacecraft are α* and the difference between the components of the moment of inertia for the spacecraft. (research papers)

  15. Drawing of American ASTP crewmen searching for Soviet Soyuz spacecraft

    Science.gov (United States)

    1975-01-01

    The American Apollo Soyuz Test Project (ASTP) crewmen search the skies for the Soviet Soyuz spacecraft in this humorous artwork by Cosmonaut Aleksey A. Leonov. Astronauts Vance D. Brand, Donald K. Slayton and Thomas P. Stafford (left to right) sit astride the Apollo spacecraft and Docking Module ready to lasso Soyuz. Leonov, an accomplished artist, specializes in painting on space subjects.

  16. An application of modern control theory to an elastic spacecraft

    Science.gov (United States)

    Larson, V.; Likins, P. W.

    1976-01-01

    Results are presented to illustrate the application of established procedures of linear, quadratic, Gaussian optimal estimation and control to a spacecraft with dynamically significant elastic appendages. Interpretations are provided in both time domain and frequency domain, and conclusions are drawn for a wide class of problems of flexible spacecraft attitude control.

  17. 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.

  18. Spacecraft Component Adaptive Layout Environment (SCALE): An efficient optimization tool

    Science.gov (United States)

    Fakoor, Mahdi; Ghoreishi, Seyed Mohammad Navid; Sabaghzadeh, Hossein

    2016-11-01

    For finding the optimum layout of spacecraft subsystems, important factors such as the center of gravity, moments of inertia, thermal distribution, natural frequencies, etc. should be taken into account. This large number of effective parameters makes the optimum layout process of spacecraft subsystems complex and time consuming. In this paper, an automatic tool, based on multi-objective optimization methods, is proposed for a three dimensional layout of spacecraft subsystems. In this regard, an efficient Spacecraft Component Adaptive Layout Environment (SCALE) is produced by integration of some modeling, FEM, and optimization software. SCALE automatically provides optimal solutions for a three dimensional layout of spacecraft subsystems with considering important constraints such as center of gravity, moment of inertia, thermal distribution, natural frequencies and structural strength. In order to show the superiority and efficiency of SCALE, layout of a telecommunication spacecraft and a remote sensing spacecraft are performed. The results show that, the objective functions values for obtained layouts by using SCALE are in a much better condition than traditional one i.e. Reference Baseline Solution (RBS) which is proposed by the engineering system team. This indicates the good performance and ability of SCALE for finding the optimal layout of spacecraft subsystems.

  19. A Survey of Research on Service-Spacecraft Orbit Design

    Institute of Scientific and Technical Information of China (English)

    LI Yue; ZHANG Jian-xin; ZHANG Qiang; WEI Xiao-peng

    2013-01-01

    On-orbit service spacecraft orbit problem has been addressed for decades. The research of on-orbit service spacecraft orbit can be roughly divided into orbit design and orbit optimization. The paper mainly focuses on the orbit design problem. We simply summarize of the previous works, and point out the main content of the on-orbit service spacecraft orbit design. We classify current on-orbit service spacecraft orbit design problem into parking-orbit design, maneuvering-orbit design and servicing-orbit design. Then, we give a detail description of the three specific orbits, and put forward our own ideas on the existed achievements. The paper will provide a meaningful reference for the on-orbit service spacecraft orbital design research.

  20. Vibration Control of Flexible Spacecraft Using Adaptive Controller

    Directory of Open Access Journals (Sweden)

    V.I. George

    2012-01-01

    Full Text Available The aim is to develop vibration control of flexible spacecraft by adaptive controller. A case study will be carried out which simulates planar motion of flexible spacecraft as a coupled hybrid dynamics of rigid body motion and the flexible arm vibration. The notch filter and adaptive vibration controller, which updates filter and controller parameters continuously from the sensor measurement, are implemented in the real time control. The least mean square algorithm using the adaptive notch filter is applied to the flexible spacecraft. This study will show that the adaptive vibration controller successfully stabilizes the uncertain and it will accurately control the vibration of flexible spacecraft. The Least mean square  algorithm is applied in flexible spacecraft to attenuate the vibration. The simulation studies are carried out in a Matlab/Simulink environment.

  1. Asteroid Deflection Using a Spacecraft in Restricted Keplerian Motion

    CERN Document Server

    Ketema, Yohannes

    2016-01-01

    A method for asteroid deflection that makes use of a spacecraft moving back and forth on a segment of an appropriate Keplerian orbit about the asteroid is described and evaluated. It is shown that, on average, the spacecraft describing such a trajectory can exert a significantly larger force on the asteroid than e.g. a stationary gravity tractor, thereby reducing the time needed to effect a desired velocity change for the asteroid. Furthermore, the current method does not require canted thrusters on the spacecraft (unlike a stationary gravity tractor), markedly reducing the amount of fuel needed to create a given change in the asteroid velocity. In addition, the method allows for the simultaneous use of several spacecraft, further strengthening the overall tugging effect on the asteroid, and distributing the thrust requirement among the spacecraft.

  2. Studies on black anodic coatings for spacecraft thermal control applications

    Energy Technology Data Exchange (ETDEWEB)

    Uma Rani, R.; Subba Rao, Y.; Sharma, A.K. [ISRO Satellite Centre, Bangalore (India). Thermal Systems Group

    2011-10-15

    An inorganic black colouring process using nickel sulphate and sodium sulphide was investigated on anodized aluminium alloy 6061 to provide a flat absorber black coating for spacecraft thermal control applications. Influence of colouring process parameters (concentration, pH) on the physico-optical properties of black anodic film was investigated. The nature of black anodic film was evaluated by the measurement of film thickness, micro hardness and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy studies confirmed the presence of nickel and sulphur in the black anodic coating. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion resistance of the coating. The environmental tests, namely, humidity, corrosion resistance, thermal cycling and thermo vacuum performance tests were used to evaluate the space worthiness of the coating. Optical properties of the film were measured before and after each environmental test to ascertain its stability in harsh space environment. The black anodic films provide higher thermal emittance ({proportional_to} 0.90) and solar absorptance ({proportional_to} 0.96) and their high stability during the environmental tests indicated their suitability for space and allied applications. (orig.)

  3. Material Properties of Three Candidate Elastomers for Space Seals Applications

    Science.gov (United States)

    Bastrzyk, Marta B.; Daniels, Christopher C.; Oswald, Jay J.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

    2010-01-01

    A next-generation docking system is being developed by the National Aeronautics and Space Administration (NASA) to support Constellation Space Exploration Missions to low Earth orbit (LEO), to the Moon, and to Mars. A number of investigations were carried out to quantify the properties of candidate elastomer materials for use in the main interface seal of the Low Impact Docking System (LIDS). This seal forms the gas pressure seal between two mating spacecraft. Three candidate silicone elastomer compounds were examined: Esterline ELA-SA-401, Parker Hannifin S0383-70, and Parker Hannifin S0899-50. All three materials were characterized as low-outgassing compounds, per ASTM E595, so as to minimize the contamination of optical and solar array systems. Important seal properties such as outgas levels, durometer, tensile strength, elongation to failure, glass transition temperature, permeability, compression set, Yeoh strain energy coefficients, coefficients of friction, coefficients of thermal expansion, thermal conductivity and diffusivity were measured and are reported herein.

  4. Bright low mass eclipsing binary candidates observed by STEREO

    CERN Document Server

    Wraight, K T; White, Glenn J; Norton, A J; Bewsher, D

    2012-01-01

    Observations from the Heliospheric Imagers (HI-1) on both the STEREO spacecraft have been analysed to search for bright low mass eclipsing binaries (EBs) and potential brown dwarf transits and to determine the radii of the companions. A total of 9 EB candidates have been found, ranging in brightness from V=6.59 mag to V=11.3 mag, where the radius of the companion appears to be less than 0.4 Rsol, with a diverse range of host temperatures, from 4074 K to 6925 K. Both components of one candidate, BD-07 3648, appear to be less than 0.4 Rsol and this represents a particularly interesting system for further study. The shapes of the eclipses in some cases are not clear enough to be certain they are total and the corresponding radii found should therefore be considered as lower limits. The EBs reported in this paper have either been newly found by the present analysis, or previously reported to be eclipsing by our earlier STEREO/HI-1 results. One of the new objects has subsequently been confirmed using archival Supe...

  5. Quaternion normalization in spacecraft attitude determination

    Science.gov (United States)

    Deutschmann, J.; Markley, F. L.; Bar-Itzhack, Itzhack Y.

    1993-01-01

    Attitude determination of spacecraft usually utilizes vector measurements such as Sun, center of Earth, star, and magnetic field direction to update the quaternion which determines the spacecraft orientation with respect to some reference coordinates in the three dimensional space. These measurements are usually processed by an extended Kalman filter (EKF) which yields an estimate of the attitude quaternion. Two EKF versions for quaternion estimation were presented in the literature; namely, the multiplicative EKF (MEKF) and the additive EKF (AEKF). In the multiplicative EKF, it is assumed that the error between the correct quaternion and its a-priori estimate is, by itself, a quaternion that represents the rotation necessary to bring the attitude which corresponds to the a-priori estimate of the quaternion into coincidence with the correct attitude. The EKF basically estimates this quotient quaternion and then the updated quaternion estimate is obtained by the product of the a-priori quaternion estimate and the estimate of the difference quaternion. In the additive EKF, it is assumed that the error between the a-priori quaternion estimate and the correct one is an algebraic difference between two four-tuple elements and thus the EKF is set to estimate this difference. The updated quaternion is then computed by adding the estimate of the difference to the a-priori quaternion estimate. If the quaternion estimate converges to the correct quaternion, then, naturally, the quaternion estimate has unity norm. This fact was utilized in the past to obtain superior filter performance by applying normalization to the filter measurement update of the quaternion. It was observed for the AEKF that when the attitude changed very slowly between measurements, normalization merely resulted in a faster convergence; however, when the attitude changed considerably between measurements, without filter tuning or normalization, the quaternion estimate diverged. However, when the

  6. Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data

    Energy Technology Data Exchange (ETDEWEB)

    Batalha, Natalie M.; /San Jose State U.; Rowe, Jason F.; /NASA, Ames; Bryson, Stephen T.; /NASA, Ames; Barclay, Thomas; /NASA, Ames; Burke, Christopher J.; /NASA, Ames; Caldwell, Douglas A.; /NASA, Ames; Christiansen, Jessie L.; /NASA, Ames; Mullally, Fergal; /NASA, Ames; Thompson, Susan E.; /NASA, Ames; Brown, Timothy M.; /Las Cumbres Observ.; Dupree, Andrea K.; /Harvard-Smithsonian Ctr. Astrophys. /UC, Santa Cruz

    2012-02-01

    New transiting planet candidates are identified in sixteen months (May 2009 - September 2010) of data from the Kepler spacecraft. Nearly five thousand periodic transit-like signals are vetted against astrophysical and instrumental false positives yielding 1091 viable new planet candidates, bringing the total count up to over 2,300. Improved vetting metrics are employed, contributing to higher catalog reliability. Most notable is the noise-weighted robust averaging of multiquarter photo-center offsets derived from difference image analysis which identifies likely background eclipsing binaries. Twenty-two months of photometry are used for the purpose of characterizing each of the new candidates. Ephemerides (transit epoch, T{sub 0}, and orbital period, P) are tabulated as well as the products of light curve modeling: reduced radius (R{sub P}/R{sub {star}}), reduced semi-major axis (d/R{sub {star}}), and impact parameter (b). The largest fractional increases are seen for the smallest planet candidates (197% for candidates smaller than 2R{sub {circle_plus}} compared to 52% for candidates larger than 2R{sub {circle_plus}}) and those at longer orbital periods (123% for candidates outside of 50 day orbits versus 85% for candidates inside of 50 day orbits). The gains are larger than expected from increasing the observing window from thirteen months (Quarter 1 - Quarter 5) to sixteen months (Quarter 1 - Quarter 6). This demonstrates the benefit of continued development of pipeline analysis software. The fraction of all host stars with multiple candidates has grown from 17% to 20%, and the paucity of short-period giant planets in multiple systems is still evident. The progression toward smaller planets at longer orbital periods with each new catalog release suggests that Earth-size planets in the Habitable Zone are forthcoming if, indeed, such planets are abundant.

  7. A Low Cost Spacecraft Architecture for Robotic Lunar Exploration Projects

    Science.gov (United States)

    Lemke, Lawrence G.; Gonzales, Andrew A.

    2006-01-01

    A program of frequent, capable, but affordable lunar robotic missions prior to return of humans to the moon can contribute to the Vision for Space Exploration (VSE) NASA is tasked to execute. The Lunar Reconnaissance Orbiter (LRO) and its secondary payload are scheduled to orbit the moon, and impact it, respectively, in 2008. It is expected that the sequence of missions occurring for approximately the decade after 2008 will place an increasing emphasis on soft landed payloads. These missions are requited to explore intrinsic characteristics of the moon, such as hydrogen distribution in the regolith, and levitated dust, to demonstrate the ability to access and process in-situ resources, and to demonstrate functions critical to supporting human presence, such as automated precision navigation and landing. Additional factors governing the design of spacecraft to accomplish this diverse set of objectives are: operating within a relatively modest funding profile, the need tb visit multiple sites (both polar and equatorial) repeatedly, and to use the current generation of launch vehicles. In the US, this implies use of the Evolved Expendable Launch Vehicles, or EELVs, although this design philosophy may be extended to launch vehicles of other nations, as well. Many of these factors are seemingly inconsistent with each other. For example, the cost of a spacecraft usually increases with mass; therefore the desire to fly frequent, modestly priced spacecraft seems to imply small spacecraft (autonomous navigation and soft landing) also usually increases cost. A strategy for spacecraft design that meets these conflicting requirements is presented. Taken together, spacecraft structure and propulsion subsystems constitute the majority of spacecraft mass; saving development and integration cost on these elements is critical to controlling cost. Therefore, a low cost, modular design for spacecraft structure and propulsion subsystems is presented which may be easily scaled up or

  8. 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

  9. A Technology Program that Rescues Spacecraft

    Science.gov (United States)

    Deutsch, Leslie J.; Lesh, J. R.

    2004-03-01

    There has never been a long-duration deep space mission that did not have unexpected problems during operations. JPL's Interplanetary Network Directorate (IND) Technology Program was created to develop new and improved methods of communication, navigation, and operations. A side benefit of the program is that it maintains a cadre of human talent and experimental systems that can be brought to bear on unexpected problems that may occur during mission operations. Solutions fall into four categories: applying new technology during operations to enhance science performance, developing new operational strategies, providing domain experts to help find solutions, and providing special facilities to trouble-shoot problems. These are illustrated here using five specific examples of spacecraft anomalies that have been solved using, at least in part, expertise or facilities from the IND Technology Program: Mariner 10, Voyager, Galileo, SOHO, and Cassini/Huygens. In this era of careful cost management, and emphasis on returns-on-investment, it is important to recognize this crucial additional benefit from such technology program investments.

  10. Kalman Filter for Spinning Spacecraft Attitude Estimation

    Science.gov (United States)

    Markley, F. Landis; Sedlak, Joseph E.

    2008-01-01

    This paper presents a Kalman filter using a seven-component attitude state vector comprising the angular momentum components in an inertial reference frame, the angular momentum components in the body frame, and a rotation angle. The relatively slow variation of these parameters makes this parameterization advantageous for spinning spacecraft attitude estimation. The filter accounts for the constraint that the magnitude of the angular momentum vector is the same in the inertial and body frames by employing a reduced six-component error state. Four variants of the filter, defined by different choices for the reduced error state, are tested against a quaternion-based filter using simulated data for the THEMIS mission. Three of these variants choose three of the components of the error state to be the infinitesimal attitude error angles, facilitating the computation of measurement sensitivity matrices and causing the usual 3x3 attitude covariance matrix to be a submatrix of the 6x6 covariance of the error state. These variants differ in their choice for the other three components of the error state. The variant employing the infinitesimal attitude error angles and the angular momentum components in an inertial reference frame as the error state shows the best combination of robustness and efficiency in the simulations. Attitude estimation results using THEMIS flight data are also presented.

  11. NASA Medical Response to Human Spacecraft Accidents

    Science.gov (United States)

    Patlach, Robert

    2011-01-01

    This slide presentation reviews NASA's role in the response to spacecraft accidents that involve human fatalities or injuries. Particular attention is given to the work of the Mishap Investigation Team (MIT), the first response to the accidents and the interface to the accident investigation board. The MIT does not investigate the accident, but the objective of the MIT is to gather, guard, preserve and document the evidence. The primary medical objectives of the MIT is to receive, analyze, identify, and transport human remains, provide assistance in the recovery effort, and to provide family Casualty Coordinators with latest recovery information. The MIT while it does not determine the cause of the accident, it acts as the fact gathering arm of the Mishap Investigation Board (MIB), which when it is activated may chose to continue to use the MIT as its field investigation resource. The MIT membership and the specific responsibilities and tasks of the flight surgeon is reviewed. The current law establishing the process is also reviewed.

  12. An AFDX Network for Spacecraft Data Handling

    Science.gov (United States)

    Deredempt, Marie-Helene; Kollias, Vangelis; Sun, Zhili; Canamares, Ernest; Ricco, Philippe

    2014-08-01

    In aeronautical domain, ARINC-664 Part 7 specification (AFDX) [4] provides the enabling technology for interfacing equipment in Integrated Modular Avionics (IMA) architectures. The complementary part of AFDX for a complete interoperability - Time and Space Partitioning (ARINC 653) concepts [1]- was already studied as part of space domain ESA roadmap (i.e. IMA4Space project) Standardized IMA based architecture is already considered in aeronautical domain as more flexible, reliable and secure. Integration and validation become simple, using a common set of tools and data base and could be done by part on different means with the same definition (hardware and software test benches, flight control or alarm test benches, simulator and flight test installation). In some area, requirements in terms of data processing are quite similar in space domain and the concept could be applicable to take benefit of the technology itself and of the panel of hardware and software solutions and tools available on the market. The Mission project (Methodology and assessment for the applicability of ARINC-664 (AFDX) in Satellite/Spacecraft on-board communicatION networks), as an FP7 initiative for bringing terrestrial SME research into the space domain started to evaluate the applicability of the standard in space domain.

  13. Dielectric Heaters for Testing Spacecraft Nuclear Reactors

    Science.gov (United States)

    Sims, William Herbert; Bitteker, Leo; Godfroy, Thomas

    2006-01-01

    A document proposes the development of radio-frequency-(RF)-driven dielectric heaters for non-nuclear thermal testing of the cores of nuclear-fission reactors for spacecraft. Like the electrical-resistance heaters used heretofore for such testing, the dielectric heaters would be inserted in the reactors in place of nuclear fuel rods. A typical heater according to the proposal would consist of a rod of lossy dielectric material sized and shaped like a fuel rod and containing an electrically conductive rod along its center line. Exploiting the dielectric loss mechanism that is usually considered a nuisance in other applications, an RF signal, typically at a frequency .50 MHz and an amplitude between 2 and 5 kV, would be applied to the central conductor to heat the dielectric material. The main advantage of the proposal is that the wiring needed for the RF dielectric heating would be simpler and easier to fabricate than is the wiring needed for resistance heating. In some applications, it might be possible to eliminate all heater wiring and, instead, beam the RF heating power into the dielectric rods from external antennas.

  14. Dust impact signals on the wind spacecraft

    Science.gov (United States)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.

    2016-02-01

    We analyze waveforms recorded by the Time Domain Sampler of the WAVES experiment on Wind which are similar to impulsive waveforms observed by the S/WAVES experiment on STEREO. These have been interpreted as dust impacts by Meyer-Vernet et al. and M. L. Kaiser and K. Goetz and extensively analyzed by Zaslavsky et al. The mechanism for coupling the emission to the antennas to produce an electrical signal is still not well understood, however. One suggested mechanism for coupling of the impact to the antenna is that the spacecraft body changes potential with respect to the surrounding plasma but the antennas do not (the body mechanism). Another class of mechanisms, with several forms, is that the charge of the emitted cloud interacts with the antennas. The Wind data show that both are operating. The time domain shapes of the dust pulses are highly variable but we have little understanding of what provides these shapes. One feature of the STEREO data has been interpreted as impacts from high velocity nanoparticles entrained by the solar wind. We have not found evidence for fast nanodust in the Wind data. An appreciable fraction of the impacts observed on Wind is consistent with interstellar dust. The impact rates do not follow a Poisson distribution, expected for random independent events, and this is interpreted as bunching. We have not succeeded in relating this bunching to known meteor showers, and they do not repeat from 1 year to the next. The data suggest bunching by fields in the heliosphere.

  15. Humidity Testing for Human Rated Spacecraft

    Science.gov (United States)

    Johnson, Gary B.

    2009-01-01

    Determination that equipment can operate in and survive exposure to the humidity environments unique to human rated spacecraft presents widely varying challenges. Equipment may need to operate in habitable volumes where the atmosphere contains perspiration, exhalation, and residual moisture. Equipment located outside the pressurized volumes may be exposed to repetitive diurnal cycles that may result in moisture absorption and/or condensation. Equipment may be thermally affected by conduction to coldplate or structure, by forced or ambient air convection (hot/cold or wet/dry), or by radiation to space through windows or hatches. The equipment s on/off state also contributes to the equipment s susceptibility to humidity. Like-equipment is sometimes used in more than one location and under varying operational modes. Due to these challenges, developing a test scenario that bounds all physical, environmental and operational modes for both pressurized and unpressurized volumes requires an integrated assessment to determine the "worst-case combined conditions." Such an assessment was performed for the Constellation program, considering all of the aforementioned variables; and a test profile was developed based on approximately 300 variable combinations. The test profile has been vetted by several subject matter experts and partially validated by testing. Final testing to determine the efficacy of the test profile on actual space hardware is in the planning stages. When validation is completed, the test profile will be formally incorporated into NASA document CxP 30036, "Constellation Environmental Qualification and Acceptance Testing Requirements (CEQATR)."

  16. Spacecraft with gradual acceleration of solar panels

    Science.gov (United States)

    Merhav, Tamir R. (Inventor); Festa, Michael T. (Inventor); Stetson, Jr., John B. (Inventor)

    1996-01-01

    A spacecraft (8) includes a movable appendage such as solar panels (12) operated by a stepping motor (28) driven by pulses (311). In order to reduce vibration andor attitude error, the drive pulses are generated by a clock down-counter (312) with variable count ratio. Predetermined desired clock ratios are stored in selectable memories (314a-d), and the selected ratio (R) is coupled to a comparator (330) together with the current ratio (C). An up-down counter (340) establishes the current count-down ratio by counting toward the desired ratio under the control of the comparator; thus, a step change of solar panel speed never occurs. When a direction change is commanded, a flag signal generator (350) disables the selectable memories, and enables a further store (360), which generates a count ratio representing a very slow solar panel rotational rate, so that the rotational rate always slows to a low value before direction is changed. The principles of the invention are applicable to any movable appendage.

  17. Wide Tuning Capability for Spacecraft Transponders

    Science.gov (United States)

    Lux, James; Mysoor, Narayan; Shah, Biren; Cook, Brian; Smith, Scott

    2007-01-01

    A document presents additional information on the means of implementing a capability for wide tuning of microwave receiver and transmitter frequencies in the development reported in the immediately preceding article, VCO PLL Frequency Synthesizers for Spacecraft Transponders (NPO- 42909). The reference frequency for a PLL-based frequency synthesizer is derived from a numerically controlled oscillator (NCO) implemented in digital logic, such that almost any reference frequency can be derived from a fixed crystal reference oscillator with microhertz precision. The frequency of the NCO is adjusted to track the received signal, then used to create another NCO frequency used to synthesize the transmitted signal coherent with, and at a specified frequency ratio to, the received signal. The frequencies can be changed, even during operation, through suitable digital programming. The NCOs and the related tracking loops and coherent turnaround logic are implemented in a field-programmable gate array (FPGA). The interface between the analog microwave receiver and transmitter circuits and the FPGA includes analog-to-digital and digital-toanalog converters, the sampling rates of which are chosen to minimize spurious signals and otherwise optimize performance. Several mixers and filters are used to properly route various signals.

  18. VCO PLL Frequency Synthesizers for Spacecraft Transponders

    Science.gov (United States)

    Smith, Scott; Mysoor, Narayan; Lux, James; Cook, Brian

    2007-01-01

    Two documents discuss a breadboard version of advanced transponders that, when fully developed, would be installed on future spacecraft to fly in deep space. These transponders will be required to be capable of operation on any deepspace- communications uplink frequency channel between 7,145 and 7,235 MHz, and any downlink frequency channel between 8,400 and 8,500 MHz. The document focuses on the design and operation of frequency synthesizers for the receiver and transmitter. Heretofore, frequency synthesizers in deep-space transponders have been based on dielectric resonator oscillators (DROs), which do not have the wide tuning bandwidth necessary to tune over all channels in the uplink or downlink frequency bands. To satisfy the requirement for tuning bandwidth, the present frequency synthesizers are based on voltage-controlled-oscillator (VCO) phase-locked loops (PLLs) implemented by use of monolithic microwave integrated circuits (MMICs) implemented using inGaP heterojunction bipolar transistor (HBT) technology. MMIC VCO PLL frequency synthesizers similar to the present ones have been used in commercial and military applications but, until now, have exhibited too much phase noise for use in deep-space transponders. The present frequency synthesizers contain advanced MMIC VCOs, which use HBT technology and have lower levels of flicker (1/f) phase noise. When these MMIC VCOs are used with high-speed MMIC frequency dividers, it becomes possible to obtain the required combination of frequency agility and low phase noise.

  19. Applying a cloud computing approach to storage architectures for spacecraft

    Science.gov (United States)

    Baldor, Sue A.; Quiroz, Carlos; Wood, Paul

    As sensor technologies, processor speeds, and memory densities increase, spacecraft command, control, processing, and data storage systems have grown in complexity to take advantage of these improvements and expand the possible missions of spacecraft. Spacecraft systems engineers are increasingly looking for novel ways to address this growth in complexity and mitigate associated risks. Looking to conventional computing, many solutions have been executed to solve both the problem of complexity and heterogeneity in systems. In particular, the cloud-based paradigm provides a solution for distributing applications and storage capabilities across multiple platforms. In this paper, we propose utilizing a cloud-like architecture to provide a scalable mechanism for providing mass storage in spacecraft networks that can be reused on multiple spacecraft systems. By presenting a consistent interface to applications and devices that request data to be stored, complex systems designed by multiple organizations may be more readily integrated. Behind the abstraction, the cloud storage capability would manage wear-leveling, power consumption, and other attributes related to the physical memory devices, critical components in any mass storage solution for spacecraft. Our approach employs SpaceWire networks and SpaceWire-capable devices, although the concept could easily be extended to non-heterogeneous networks consisting of multiple spacecraft and potentially the ground segment.

  20. 11 CFR 100.154 - Candidate debates.

    Science.gov (United States)

    2010-01-01

    ... Expenditures § 100.154 Candidate debates. Funds used to defray costs incurred in staging candidate debates in accordance with the provisions of 11 CFR 110.13 and 114.4(f) are not expenditures. ... 11 Federal Elections 1 2010-01-01 2010-01-01 false Candidate debates. 100.154 Section...

  1. 11 CFR 100.92 - Candidate debates.

    Science.gov (United States)

    2010-01-01

    ... Contributions § 100.92 Candidate debates. Funds provided to defray costs incurred in staging candidate debates in accordance with the provisions of 11 CFR 110.13 and 114.4(f) are not contributions. ... 11 Federal Elections 1 2010-01-01 2010-01-01 false Candidate debates. 100.92 Section...

  2. 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....

  3. Empirical models for spacecraft damage from orbital debris penetration and effects on spacecraft survivability

    Science.gov (United States)

    Williamsen, Joel; Schonberg, William

    1997-01-01

    Semi-empirical models of hole diameter and tip-to-tip crack length for different multi-wall shielding systems currently under development for the International Space Station are presented. These equations were developed using light gas gun test data at impact velocities of 6.5 km/s and inhibited shaped charge test data for an impact velocity of 11.3 km/s. These models are incorporated into a survivability analysis using the manned spacecraft crew survivability computer code to determine whether or not module unzipping or crew incapacitation would occur under a specific set of impact conditions.

  4. Garment selection for cleanrooms and controlled environments for spacecraft

    Science.gov (United States)

    Watts, Ethel J.

    Strict contamination control practices are exercised throughout the lifetime of a spacecraft in order to satisfy the performance requirements of the system. Spacecraft materials are carefully selected to have low outgassing values and particulate deposition. Parts are cleaned, and the vehicle is assembled in cleanrooms and work stations having controlled environments. Specifications are examined which govern the selection of special items of clothing designed to protect spacecraft from contaminants released by personnel and by garments. Special clothing includes coveralls, footwear, and head/face covers. Garments appropriate for both hazardous (meltproof as well as flame resistant), and nonhazardous operations are described.

  5. 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.

  6. 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

  7. Application of DSN spacecraft tracking technology to experimental gravitation

    Science.gov (United States)

    Anderson, J. D.; Estabrook, F. B.

    1978-01-01

    Spacecraft tracking technology of the Deep Space Net (DSN) has been used in the past to measure the general-relativistic increase in round-trip group delay between earth and a spacecraft. As the DSN technology continues to improve, other gravitational experiments will become possible. Two possibilities are discussed in this paper. The first concerns the application of solar-system dynamics to the testing of general relativity. The second involves the detection of VLF gravitational radiation (0.1 to 0.0001 Hz) by means of Doppler tracking of spacecraft.

  8. Thermal and Mechanical Performance of a Carbon/Carbon Composite Spacecraft Radiator

    Science.gov (United States)

    Kuhn, Jonathan; Benner, Steve; Butler, Dan; Silk, Eric

    1999-01-01

    Carbon-carbon composite materials offer greater thermal efficiency, stiffness to weight ratio, tailorability, and dimensional stability than aluminum. These lightweight thermal materials could significantly reduce the overall costs associated with satellite thermal control and weight. However, the high cost and long lead-time for carbon-carbon manufacture have limited their widespread usage. Consequently, an informal partnership between government and industrial personnel called the Carbon-Carbon Spacecraft Radiator Partnership (CSRP) was created to foster carbon-carbon composite use for thermally and structurally demanding space radiator applications. The first CSRP flight opportunity is on the New Millennium Program (NMP) Earth Orbiter-1 (EO-1) spacecraft, scheduled for launch in late 1999. For EO-1, the CSRP designed and fabricated a Carbon-Carbon Radiator (CCR) with carbon-carbon facesheets and aluminum honeycomb core, which will also serve as a structural shear panel. While carbon-carbon is an ideal thermal candidate for spacecraft radiators, in practice there are technical challenges that may compromise performance. In this work, the thermal and mechanical performance of the EO-1 CCR is assessed by analysis and testing. Both then-nal and mechanical analyses were conducted to predict the radiator response to anticipated launch and on-orbit loads. The thermal model developed was based on thermal balance test conditions. The thermal analysis was performed using SINDA version 4.0. Structural finite element modeling and analysis were performed using SDRC/1-DEAS and UAI/NASTRAN, respectively. In addition, the CCR was subjected to flight qualification thermal/vacuum and vibration tests. The panel meets or exceeds the requirements for space flight and demonstrates promise for future satellite missions.

  9. The electrical power subsystem of the Pioneer F/G spacecraft.

    Science.gov (United States)

    Reppucci, G. M.; Jesse, E.

    1971-01-01

    The Pioneer F/G spacecraft is the first to use radioisotope thermoelectric generators (RTG's) for a long duration interplanetary mission. This paper describes the design of the spacecraft power subsystem which meets the unique requirements of such a mission. The primary power source consists of four SNAP 19 RTG's. The 4.2 volt dc outputs of the RTG's are inverted to higher voltage ac by four inverters which are connected in parallel at their outputs. A power control unit (PCU) regulates the ac output of the inverters such that the RTG's are operated at near maximum power voltage throughout the mission. The PCU also contains charge and discharge controls for a silver cadmium battery which supplements the RTG's if load requirements temporarily exceed RTG power output. Battery reliability is enhanced by overcharge and cell reversal protection electronics which are provided for each cell. Multiple, low voltage, regulated dc outputs which supply power to the spacecraft subsystems are provided by a central transformer-rectifier-filter unit (CTRF). The CTRF operates directly from the regulated ac bus.

  10. Spacecraft Environment May Reduce Resistance To Infection

    Science.gov (United States)

    Pierson, Duane L.; Ott, C. Mark; Castro, V. A.; Leal, Melanie; Mehta, Satish K.

    2006-01-01

    Living and working in a spacecraft exposes the crew to a unique environment. This environment includes microgravity, increased radiation, chemical and biological contamination, and a variety of stressors. Disturbances in this balance are often manifested by diminished immunity in astronauts/cosmonauts. Reactivation of Epstein- Barr virus (EBV), cytomegalovirus (CMV), and varicella-zoster virus (VZV) has been used as an indicator of immune status. Reactivation of EBV and VZV were detected and quantified in saliva. CMV was measured in urine. The DNA was extracted using a Qiagen Inc. kit and viral DNA was detected by real time polymerase chain reaction (PCR) based assay with Taqman 7700 (PE Biosystems). Patterns of Epstein-Barr virus (EBV) reactivation in 32 astronauts and 18 healthy age-matched control subjects were characterized by quantifying EBV shedding. Saliva samples were collected before, during, and after 10 space shuttle missions of 5 to 14 d duration. Of 1398 saliva specimens from 32 astronauts, 314 (23%) were positive for EBV DNA. Examination by flight phase showed that 29% of the saliva specimens collected from 28 astronauts before flight were positive for EBV DNA, as were 16% of those collected from 25 astronauts during flight and 16% of those collected after flight from 23 astronauts. The mean number of EBV copies/mL from samples taken during the flights was 417, ten-fold greater (p conditions. Data indicates that space flight is a unique stress environment that may produce stress-induced changes in the host-microbe relationship resulting in increased risk of infection.

  11. LCOGT Network observations of spacecraft target comets

    Science.gov (United States)

    Lister, Tim; Knight, Matthew M.; Snodgrass, Colin; Samarasinha, Nalin H.

    2015-01-01

    Las Cumbres Observatory Global Telescope (LCOGT) network currently has 12 telescopes at 6 locations in the northern and southern hemispheres with expansion plans for more. This network is versatile and can respond rapidly to target of opportunity events and also perform long term monitoring of slowly changing astronomical phenomena.We have been using the LCOGT Network to perform photometric monitoring of comet 67P/Churyumov-Gerasimenko to support the ESA Rosetta comet mission and of C/2013 A1 (Siding Spring) as part of the ground-based observation teams for these important comets. This broadband photometry will allow a vital link between the detailed in-situ measurements made by the spacecraft and the global properties of the coma, at a time when the comet is only visible for short periods from single sites. The science we can extract includes the rotational state of the nucleus, characterization of the nucleus' activity, gas and dust properties in the coma (e.g., outflow velocities), chemical origin of gas species in the coma, and temporal behavior of the coma structure when the comet is close to the sun. Comet Siding Spring is a dynamically new comet on its first approach to the Sun that will pass close to Mars, so we can directly sample the composition of an original unaltered remnant of the protoplanetary disc. We will also be making use of specialized comet filters available at LCOGT's 2-m Faulkes Telescope North (FTN) to obtain a unique data set on comet C/2013 A1 (Siding Spring), as part of a large worldwide campaign. As one of only two robotic telescope equipped with cometary narrowband filters in the Northern hemisphere and having the largest aperture plus a high quality site, FTN can provide critical regular monitoring that cannot be achieved by any other single facility in the campaign.

  12. Candidate worldviews for design theory

    DEFF Research Database (Denmark)

    Galle, Per

    2008-01-01

    Our growing body of design theory risks being infected by more inconsistency than is justifiable by genuine disagreement among design theorists. Taking my cue from C. S. Peirce, who argued that theory inevitably rests on basic metaphysical assumptions that theorists ought to be critically aware of......, I demonstrate how ‘insidious inconsistency’ may infect design theory if we ignore his admonition. As a possible remedy, I propose a method by which the philosophy of design may develop sound metaphysical foundations (‘worldviews’) for design theory – and generate philosophical insights into design...... at the same time. Examples are given of how the first steps of the method may be carried out and a number of candidate worldviews are outlined and briefly discussed. In its own way, each worldview answers certain fundamental questions about the nature of design. These include the ontological question of what...

  13. The Spacecraft Materials Selector: An Artificial Intelligence System for Preliminary Design Trade Studies, Materials Assessments, and Estimates of Environments Present

    Science.gov (United States)

    Pippin, H. G.; Woll, S. L. B.

    2000-01-01

    Institutions need ways to retain valuable information even as experienced individuals leave an organization. Modern electronic systems have enough capacity to retain large quantities of information that can mitigate the loss of experience. Performance information for long-term space applications is relatively scarce and specific information (typically held by a few individuals within a single project) is often rather narrowly distributed. Spacecraft operate under severe conditions and the consequences of hardware and/or system failures, in terms of cost, loss of information, and time required to replace the loss, are extreme. These risk factors place a premium on appropriate choice of materials and components for space applications. An expert system is a very cost-effective method for sharing valuable and scarce information about spacecraft performance. Boeing has an artificial intelligence software package, called the Boeing Expert System Tool (BEST), to construct and operate knowledge bases to selectively recall and distribute information about specific subjects. A specific knowledge base to evaluate the on-orbit performance of selected materials on spacecraft has been developed under contract to the NASA SEE program. The performance capabilities of the Spacecraft Materials Selector (SMS) knowledge base are described. The knowledge base is a backward-chaining, rule-based system. The user answers a sequence of questions, and the expert system provides estimates of optical and mechanical performance of selected materials under specific environmental conditions. The initial operating capability of the system will include data for Kapton, silverized Teflon, selected paints, silicone-based materials, and certain metals. For situations where a mission profile (launch date, orbital parameters, mission duration, spacecraft orientation) is not precisely defined, the knowledge base still attempts to provide qualitative observations about materials performance and likely

  14. A Data Abstraction Architecture for Spacecraft Autonomy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft generate huge amounts of data. A significant challenge for both human operators and autonomous control systems is ensuring that the right data (and...

  15. Aerogel Insulation for the Thermal Protection of Venus Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — One of NASA's primary goals for the next decade is the design, development and launch of a spacecraft aimed at the in-situ exploration of the deep atmosphere and...

  16. A Self-Regulating Freezable Heat Exchanger for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A spacecraft thermal control system must keep the vehicle, avionics and atmosphere (if crewed) within a defined temperature range. Since water is non-toxic and good...

  17. Spacecraft Water Regeneration by Catalytic Wet Air Oxidation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to develop advanced catalysts for a volatile removal assembly used to purify spacecraft water. The innovation of the proposed...

  18. Modeling Vacuum Arcs On Spacecraft Solar Panel Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecraft charging and subsequent vacuum arcing poses a significant threat to satellites in LEO and GEO plasma conditions. Localized arc discharges can cause a...

  19. High Throughput Hall Thruster for Small Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek is developing a high throughput nominal 100-W Hall Effect Thruster. This device is well sized for spacecraft ranging in size from several tens of kilograms to...

  20. Applicability of ISO 16697 Data to Spacecraft Fire Fighting Strategies

    Science.gov (United States)

    Hirsch, David B.; Beeson, Harold D.

    2012-01-01

    Presentation Agenda: (1) Selected variables affecting oxygen consumption during spacecraft fires, (2) General overview of ISO 16697, (3) Estimated amounts of material consumed during combustion in typical ISS enclosures, (4) Discussion on potential applications.

  1. Autonomous Supervisory Engine for Multi-Spacecraft Formation Flying Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of this project is to develop an onboard, autonomous Multi-spacecraft Supervisory Engine (MSE) for formation-flying guidance, navigation and...

  2. Triple3 Redundant Spacecraft Subsystems (T3RSS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Redefine Technologies, along with researchers at the University of Colorado, will use three redundancy methods to decrease the susceptibility of a spacecraft, on a...

  3. Foil Gas Bearing Supported Quiet Fan for Spacecraft Ventilation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Developing a quiet fan for Environmental Control and Life Support systems to enhance the livable environment within the spacecraft has been a challenge. A Foil Gas...

  4. High Throughput Hall Thruster for Small Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek Co. Inc. proposes to develop a high throughput, nominal 100 W Hall Effect Thruster (HET). This HET will be sized for small spacecraft (< 180 kg), including...

  5. A multi-spacecraft formation approach to space debris surveillance

    Science.gov (United States)

    Felicetti, Leonard; Emami, M. Reza

    2016-10-01

    This paper proposes a new mission concept devoted to the identification and tracking of space debris through observations made by multiple spacecraft. Specifically, a formation of spacecraft has been designed taking into account the characteristics and requirements of the utilized optical sensors as well as the constraints imposed by sun illumination and visibility conditions. The debris observations are then shared among the team of spacecraft, and processed onboard of a "hosting leader" to estimate the debris motion by means of Kalman filtering techniques. The primary contribution of this paper resides on the application of a distributed coordination architecture, which provides an autonomous and robust ability to dynamically form spacecraft teams once the target has been detected, and to dynamically build a processing network for the orbit determination of space debris. The team performance, in terms of accuracy, readiness and number of the detected objects, is discussed through numerical simulations.

  6. Indonesian Islands as seen from Gemini 11 spacecraft

    Science.gov (United States)

    1966-01-01

    Indonesian Islands (partial cloud cover): Sumatra, Java, Bali, Borneo, Sumbawa, as photographed from the Gemini 11 spacecraft during its 26th revolution of the earth, at an altitude of 570 nautical miles.

  7. Micro GC's for Contaminant Monitoring in Spacecraft Air Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this proposal is to create new gas chromatographs (GCs) for contaminant monitoring in spacecraft air that do not require any reagents or special...

  8. Autonomous Spacecraft Navigation Based on Pulsar Timing Information

    CERN Document Server

    Bernhardt, Mike Georg; Prinz, Tobias; Breithuth, Ferdinand Maximilian; Walter, Ulrich

    2011-01-01

    We discuss the possibility of an autonomous navigation system for spacecraft that is based on pulsar timing data. Pulsars are rapidly rotating neutron stars that are observable as variable celestial sources of electromagnetic radiation. Their periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the use of GPS satellites for navigation on Earth. By comparing pulse arrival times measured on-board the spacecraft with predicted pulse arrivals at some reference location, the spacecraft position can be determined autonomously with accuracies on the order of 5 kilometres. For a spacecraft at a distance of 10 astronomical units from Earth (e.g., Earth-Saturn), this means an improvement by a factor of 8 compared to conventional methods. Therefore this new technology is an alternative to standard navigation based on radio tracking by ground stations, without the disadvantages of uncertainty in...

  9. Advanced Portable Fine Water Mist Fire Extinguisher for Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fine water mist (FWM) is a promising replacement technology for fire suppression on the next generation of manned spacecraft. It offers advantages in performance,...

  10. Trace Contaminant Monitor for Air in Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A need exists for analyzers that can measure trace contaminants in air on board spacecraft. Toxic gas buildup can endanger the crew particularly during long...

  11. Interactive systems design and synthesis of future spacecraft concepts

    Science.gov (United States)

    Wright, R. L.; Deryder, D. D.; Ferebee, M. J., Jr.

    1984-01-01

    An interactive systems design and synthesis is performed on future spacecraft concepts using the Interactive Design and Evaluation of Advanced spacecraft (IDEAS) computer-aided design and analysis system. The capabilities and advantages of the systems-oriented interactive computer-aided design and analysis system are described. The synthesis of both large antenna and space station concepts, and space station evolutionary growth is demonstrated. The IDEAS program provides the user with both an interactive graphics and an interactive computing capability which consists of over 40 multidisciplinary synthesis and analysis modules. Thus, the user can create, analyze and conduct parametric studies and modify Earth-orbiting spacecraft designs (space stations, large antennas or platforms, and technologically advanced spacecraft) at an interactive terminal with relative ease. The IDEAS approach is useful during the conceptual design phase of advanced space missions when a multiplicity of parameters and concepts must be analyzed and evaluated in a cost-effective and timely manner.

  12. The Impact of Autonomy Technology on Spacecraft Software Architecture

    Science.gov (United States)

    Gamble, E. B., Jr.

    1998-01-01

    Autonomy technology for high-level, closed-loop control of spacecraft offers considerable benefits to space-flight projects. Those benefits can enable whole new classes of missions; however, they are not without cost.

  13. Wireless Data and Power Transfer on Small Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Achieving low-cost space missions implies lowering all phases of mission development, including spacecraft design, assembly, integration and test. The concept of...

  14. Diagnosing Faults in Electrical Power Systems of Spacecraft and Aircraft

    Data.gov (United States)

    National Aeronautics and Space Administration — Electrical power systems play a critical role in spacecraft and aircraft, and they exhibit a rich variety of failure modes. This paper discusses electrical power...

  15. Spacecraft Thermal Control System Not Requiring Power Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The thermal management of spacecraft would be enhanced by dynamic control over surface emissivity in the mid-infrared. In this SBIR program, Triton Systems proposes...

  16. Investigation of Correction Method of the Spacecraft Low Altitude Ranging

    CERN Document Server

    Liu, Jing-Lei; Wu, Shi-Tong; Huang, Wei

    2015-01-01

    gamma ray altitude control system is an important equipment for deep space exploration and sample return mission, its main purpose is a low altitude measurement of the spacecraft based on Compton Effect at the moment when it lands on extraterrestrial celestial or sampling returns to the Earth land, and an ignition altitude correction of the spacecraft retrograde landing rocket at different landing speeds. This paper presents an ignition altitude correction method of the spacecraft at different landing speeds, based on the number of particles gamma ray reflected field gradient graded. Through the establishment of a theoretical model, its algorithm feasibility is proved by a mathematical derivation and verified by an experiment, and also the adaptability of the algorithm under different parameters is described. The method provides a certain value for landing control of the deep space exploration spacecraft landing the planet surface.

  17. Distributed Control Architectures for Precision Spacecraft Formations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LaunchPoint Technologies, Inc. (LaunchPoint) proposes to develop synthesis methods and design architectures for distributed control systems in precision spacecraft...

  18. Influence of Natural Environments in Spacecraft Design, Development, and Operation

    Science.gov (United States)

    Edwards, David L.

    2012-01-01

    The natural environment has a great influence on the ability of spacecraft to perform according to mission design specification. Compatibility with the natural environment is a primary factor in determining the functional lifetime of the spacecraft. The spacecraft being designed and developed today are growing in complexity. In many instances, the increased complexity also increases its sensitivity to environmental effects. Sensitivities to the natural environment can be tempered through appropriate design measures, mitigation strategies, and/or the acceptance of known risk. The design engineer must understand the effects of the natural environment on the spacecraft and its components; while having an in-depth knowledge of mitigation strategies. Too much protection incurs unnecessary expense, and often times excessive mass; while too little protection can easily lead to premature mission loss. This presentation will provide a brief overview of both the natural environment and its effects and provide some insight into mitigation strategies.

  19. Nuclear-powered Hysat spacecraft: comparative design study

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Passive Devices for Advanced Fluid Management aboard Spacecraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Acute challenges are faced by the designers of fluid systems for spacecraft because of the persistently unfamiliar and unforgiving low-g environment. For example,...

  1. Reactor/Brayton power systems for nuclear electric spacecraft

    International Nuclear Information System (INIS)

    Studies are currently underway to assess the technological feasibility of a nuclear-reactor-powered spacecraft propelled by electric thrusters. The purpose of this study was to provide comparative information on a closed cycle gas turbine power conversion system

  2. Novel Metal Organic Framework Synthesis for Spacecraft Oxygen Capture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Busek and University of Utah propose to develop novel metal organic framework (MOF) material to efficiently capture oxygen in spacecraft cabin environment. The...

  3. High-Performance Contaminant Monitor for Spacecraft Project

    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...

  4. Monitoring and forecasting of great radiation hazards for spacecraft and aircrafts by online cosmic ray data

    Directory of Open Access Journals (Sweden)

    L. I. Dorman

    2005-11-01

    Full Text Available We show that an exact forecast of great radiation hazard in space, in the magnetosphere, in the atmosphere and on the ground can be made by using high-energy particles (few GeV/nucleon and higher whose transportation from the Sun is characterized by a much bigger diffusion coefficient than for small and middle energy particles. Therefore, high energy particles come from the Sun much earlier (8-20 min after acceleration and escaping into solar wind than the main part of smaller energy particles (more than 30-60 min later, causing radiation hazard for electronics and personal health, as well as spacecraft and aircrafts. We describe here principles of an automatic set of programs that begin with "FEP-Search", used to determine the beginning of a large FEP event. After a positive signal from "FEP-Search", the following programs start working: "FEP-Research/Spectrum", and then "FEP-Research/Time of Ejection", "FEP-Research /Source" and "FEP-Research/Diffusion", which online determine properties of FEP generation and propagation. On the basis of the obtained information, the next set of programs immediately start to work: "FEP-Forecasting/Spacecrafts", "FEP-Forecasting/Aircrafts", "FEP-Forecasting/Ground", which determine the expected differential and integral fluxes and total fluency for spacecraft on different orbits, aircrafts on different airlines, and on the ground, depending on altitude and cutoff rigidity. If the level of radiation hazard is expected to be dangerous for high level technology or/and personal health, the following programs will be used "FEP-Alert/Spacecrafts", "FEP-Alert/ Aircrafts", "FEP-Alert/Ground".

  5. The Atsa Suborbital Observatory: An Observatory for a Commercial Suborbital Spacecraft

    Science.gov (United States)

    Vilas, F.; Sollitt, L. S.

    2012-12-01

    instruments or user-provided instruments. Rapid turnaround will depend only on flight frequency. Data are stored on-board for retrieval when the spacecraft lands. We provide robust instrumentation that can survive suborbital spaceflight, assessment of the feasibility of the requested observations, rigorous scripting of the telescope operation, integration of the telescope plus instrument in a provider spacecraft, and periodic preventive maintenance for the telescope and instrument suite. XCOR Aerospace's Lynx III spacecraft is the best candidate vehicle to host a suborbital astronomical observatory. Unlike other similar vehicles, the Lynx will operate with only 1 or 2 people onboard (the pilot and an operator), allowing for each mission to be totally dedicated to the observation (no tourists will be bumping about; no other experiments will affect spacecraft pointing). A stable platform, the Lynx can point to an accuracy of ± 0.5o. Fine pointing is done by the telescope system. Best of all, the Lynx has a dorsal pod that opens directly to space. For astronomical observations, the best window is NO window. Currently, we plan to deploy a 20" diameter telescope in the Lynx III dorsal pod. XCOR Aerospace has the goal of eventually maintaining a Lynx flight frequency capability of 4 times/day. As with any observatory, Atsa will be available for observations by the community at large.

  6. Local Vertical/Local Horizontal Attitude Control for Spartan Spacecraft

    OpenAIRE

    Morrissey, James; Olney, David

    1996-01-01

    A Spartan spacecraft attitude control system was reconfigured to provide attitude pointing with respect to a Local Vertical/Local Horizontal reference frame even though the baseline system uses only an initial start attitude, sun sensors, and star tracker/gyros for defining the spacecraft attitude. No earth sensors of any kind are used. Deployed from the orbiter for two days, usually for solar and stellar inertial pointing, Spartan missions use pointing programs that must be written months pr...

  7. Radio Ranging System for Guidance of Approaching Spacecraft

    Science.gov (United States)

    Manikonda, Vikram; vanDoom, Eric

    2008-01-01

    A radio communication and ranging system has been proposed for determining the relative position and orientations of two approaching spacecraft to provide guidance for docking maneuvers. On Earth, the system could be used similarly for guiding approaching aircraft and for automated positioning of large, heavy objects. In principle, the basic idea is to (1) measure distances between radio transceivers on the two spacecraft and (2) compute the relative position and orientations from the measured distances.

  8. Small Spacecraft in Support of the Lunar Exploration Program

    OpenAIRE

    Hine, Butler

    2007-01-01

    This paper analyses the ability of small, low cost spacecraft to deliver scientifically and technically useful payloads to lunar orbit and the lunar surface, in particular precursor mapping, infrastructure and in-situ resource utilization functions, that are necessary prior to human return as part of the US Vision for Space Exploration. It is based upon a technical study of the NASA-Ames Research Center’s Small Spacecraft. Following an overview of the generalized capabilities of small spacecr...

  9. Vibration Control of Flexible Spacecraft Using Adaptive Controller

    OpenAIRE

    George, V. I.; B. Ganesh Kamath; I. Thirunavukkarasu; Ciji Pearl Kurian

    2012-01-01

    The aim is to develop vibration control of flexible spacecraft by adaptive controller. A case study will be carried out which simulates planar motion of flexible spacecraft as a coupled hybrid dynamics of rigid body motion and the flexible arm vibration. The notch filter and adaptive vibration controller, which updates filter and controller parameters continuously from the sensor measurement, are implemented in the real time control. The least mean square algorithm using the adaptive notch fi...

  10. Setpoint Weighted PID Controller for the Electromechanical Actuator in Spacecraft

    OpenAIRE

    R. Sumathi; M Usha

    2014-01-01

    An intelligent control system for the rocket engine during electromechanical stage is designed and scrutinized in this paper. The rocket is the only vehicle that lift-offs the spacecraft in the space. But, the motion of the rocket can be influenced by internal and external disturbances. Furthermore, the rocket is a multi-input and multi-output nonlinear system whose dynamics are unstable and poorly understood. So the orientation of the spacecraft in precise position is so critical. Hence, att...

  11. Spacecraft Collision Probability Estimation for Rendezvous and Proximity Operations

    OpenAIRE

    Phillips, Michael R

    2012-01-01

    The topic of this thesis is on-board estimation of spacecraft collision probability for orbital rendezvous and proximity operations. All of the examples shown in this work assume that the satellite dynamics are described by the Clohessy-Wiltshire equations, and that the spacecraft are spherical. Several collision probability metrics are discussed and compared. Each metric can be placed into one of three categories. The first category provides an estimate of the instantaneous probability of co...

  12. Titan IV - An integrated spacecraft/booster view

    Science.gov (United States)

    Albrecht, Samuel W.

    1992-03-01

    The Titan IV launch vehicle is briefly described focusing on the integration process which starts with spacecraft environmental and mechanical interface requirements definition and progresses through physical mating of the spacecraft and launch vehicle, launch countdown, launch, and orbit insertion. An approach to payload integration is presented where teamwork between the government and contractor organizations provides the framework necessary for the efficient incorporation of mission unique requirements.

  13. Bremsstrahlung x ray spectra of Jupiter and Saturn: Predictions for future planetary spacecraft

    International Nuclear Information System (INIS)

    Calculations of X ray spectra due to bremsstrahlung from precipitating auroral electrons at Jupiter and Saturn are presented. The model assumes that a field-aligned potential drop accelerates a primary beam of electrons into the atmosphere where a population of secondary electrons having a power law energy dependence is generated. The spectrum at Jupiter is normalized to the soft X ray observations of Metzger et al (1983) at the low-energy end and constrained at the high-energy end by UV auroral energy requirements. The spectrum at Saturn is constructed by analogy to the Jovian case allowing for variation of the beam energy, energy flux, and scale size of the Saturnian aurora. The resulting indicate that a significant flux of X rays is emanating from both planets which may serve as a basis for conducting planetary X ray astronomy as part of future spacecraft missions to the planets

  14. The interaction of relativistic spacecrafts with the interstellar medium

    CERN Document Server

    Hoang, Thiem; Burkhart, Blakesley; Loeb, Abraham

    2016-01-01

    The Breakthrough Starshot initiative aims to launch a gram-scale spacecraft to a speed of $v\\sim 0.2$c, capable of reaching the nearest star system, $\\alpha$ Centauri, in about 20 years. However, a critical challenge for the initiative is the damage to the spacecraft by interstellar gas and dust during the journey. In this paper, we quantify the interaction of a relativistic spacecraft with gas and dust in the interstellar medium. For gas bombardment, we find that damage by track formation due to heavy elements is an important effect. We find that gas bombardment can potentially damage the surface of the spacecraft to a depth of $\\sim 0.1$ mm for quartz material after traversing a gas column of $N_{\\rm H}\\sim 2\\times 10^{18}\\rm cm^{-2}$ along the path to $\\alpha$ Centauri, whereas the effect is much weaker for graphite material. The effect of dust bombardment erodes the spacecraft surface and produces numerous craters due to explosive evaporation of surface atoms. For a spacecraft speed $v=0.2c$, we find that...

  15. 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.

  16. Three Generations of Tracking and Data Relay Satellite (TDRS) Spacecraft

    Science.gov (United States)

    Zaleski, Ron

    2016-01-01

    The current Tracking and Data Relay Satellite configuration consists of nine in-orbit satellites (four first generation, three second generation and two third generation satellites) globally distributed in geosynchronous orbit to provide near continuous data relay service to missions like Hubble Space Telescope and the International Space Station. The 1st generation spacecraft were designed by TRW/Northrop Grumman with their launches of the five spacecraft ranging from 1983 through 1995. The 2nd and 3rd generation spacecraft were designed by Boeing with their launches ranging 2000 - 2002 and 2013 - 2017 respectively. TDRS-3 is now 27 years on orbit, continues to be a capable asset for the TDRS constellation. Lack of need for inclination control combined with large fuel reserves and redundancy on critical elements provides spacecraft that operate well past design life, all of which contributes to expanded TDRS constellation support capabilities. All spacecraft generations have issues. Significant issues will be summarized with the focus on the Boeing related problems. Degradations and failures are continually assessed and provide the foundation for yearly updates to spacecraft reliability models, constellation service projections and deorbit plans (in order to meet NASAs mandate of limiting orbital debris). Even when accounting for degradations and failures, the life expectancy for the Boeing delivered 2nd generation TDRS-8, 9 10 TDRS are anticipated to be 25+ years.

  17. Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data

    CERN Document Server

    Batalha, Natalie M; Bryson, Stephen T; Barclay, Thomas; Burke, Christopher J; Caldwell, Douglas A; Christiansen, Jessie L; Mullally, Fergal; Thompson, Susan E; Brown, Timothy M; Dupree, Andrea K; Fabrycky, Daniel C; Ford, Eric B; Fortney, Jonathan J; Gilliland, Ronald L; Isaacson, Howard; Latham, David W; Marcy, Geoffrey W; Quinn, Samuel; Ragozzine, Darin; Shporer, Avi; Borucki, William J; Ciardi, David R; Gautier, Thomas N; Haas, Michael R; Jenkins, Jon M; Koch, David G; Lissauer, Jack J; Rapin, William; Basri, Gibor S; Boss, Alan P; Buchhave, Lars A; Charbonneau, David; Christensen-Dalsgaard, Joergen; Clarke, Bruce D; Cochran, William D; Demory, Brice-Olivier; Devore, Edna; Esquerdo, Gilbert A; Everett, Mark; Fressin, Francois; Geary, John C; Girouard, Forrest R; Gould, Alan; Hall, Jennifer R; Holman, Matthew J; Howard, Andrew W; Howell, Steve B; Ibrahim, Khadeejah A; Kinemuchi, K; Kjeldsen, Hans; Klaus, Todd C; Li, Jie; Lucas, Philip W; Morris, Robert L; Prsa, Andrej; Quintana, Elisa; Sanderfer, Dwight T; Sasselov, Dimitar; Seader, Shawn E; Smith, Jeffrey C; Steffen, Jason H; Still, Martin; Stumpe, Martin C; Tarter, Jill C; Tenenbaum, Peter; Torres, Guillermo; Twicken, Joseph D; Uddin, Kamal; Van Cleve, Jeffrey; Walkowicz, Lucianne; Welsh, William F

    2012-01-01

    New transiting planet candidates are identified in sixteen months (May 2009 - September 2010) of data from the Kepler spacecraft. Nearly five thousand periodic transit-like signals are vetted against astrophysical and instrumental false positives yielding 1,091 viable new planet candidates, bringing the total count up to over 2,300. Improved vetting metrics are employed, contributing to higher catalog reliability. Most notable is the noise-weighted robust averaging of multi-quarter photo-center offsets derived from difference image analysis which identifies likely background eclipsing binaries. Twenty-two months of photometry are used for the purpose of characterizing each of the new candidates. Ephemerides (transit epoch, T_0, and orbital period, P) are tabulated as well as the products of light curve modeling: reduced radius (Rp/R*), reduced semi-major axis (d/R*), and impact parameter (b). The largest fractional increases are seen for the smallest planet candidates (197% for candidates smaller than 2Re com...

  18. Revamping Spacecraft Operational Intelligence with Splunk

    Science.gov (United States)

    Hwang, Victor

    2012-01-01

    So what is Splunk? Instead of giving the technical details, which you can find online, I'll tell you what it did for me. Splunk slapped everything into one place, with one uniform format, and gave me the ability to forget about all these annoying details of where it is, how to parse it, and all that. Instead, I only need to interact with Splunk to find the data I need. This sounds simple and obvious, but it's surprising what you can do once you all of your data is indexed in one place. By having your data organized, querying becomes much easier. Let's say that I want to search telemetry for a sensor_name gtemp_1 h and to return all data that is at most five minutes old. And because Splunk can hook into a real ]time stream, this data will always be up-to-date. Extending the previous example, I can now aggregate all types of data into one view based in time. In this picture, I've got transaction logs, telemetry, and downlinked files all in one page, organized by time. Even though the raw data looks completely than this, I've defined interfaces that transform it into this uniform format. This gives me a more complete picture for the question what was the spacecraft doing at this particular time? And because querying data is simple, I can start with a big block of data and whiddle it down to what I need, rather than hunting around for the individual pieces of data that I need. When we have all the data we need, we can begin widdling down the data with Splunk's Unix-like search syntax. These three examples highlights my trial-and-error attempts to find large temperature changes. I begin by showing the first 5 temperatures, only to find that they're sorted chronologically, rather than from highest temperatures to lowest temperatures. The next line shows sorting temperatures by their values, but I find that that fs not really what I want either. I want to know the delta temperatures between readings. Looking through Splunk's user manual, I find the delta function, which

  19. Status of Galileo interim radiation electron model

    Science.gov (United States)

    Garrett, H. B.; Jun, I.; Ratliff, J. M.; Evans, R. W.; Clough, G. A.; McEntire, R. W.

    2003-01-01

    Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EDP) were used to develop a new model of Jupiter's trapped electron radiation in the jovian equatorial plane for the range 8 to 16 Jupiter radii.

  20. Cooling Shelf For Electronic Equipment

    Science.gov (United States)

    Tanzer, Herbert J.

    1989-01-01

    Heat-pipe action cools and maintains electronics at nearly constant temperature. System designed to control temperatures of spacecraft shelves or baseplates by combining honeycomb sandwich panel with reservoir of noncondensable gas and processing resulting device as variable-conductance heat pipe. Device provides flat surface for mounting heat-dissipating electronics that is effectively cooled and maintained at nearly constant temperature. Potentially useful in freeze drying, refrigeration, and air conditioning.

  1. Cardiac evaluation of liver transplant candidates

    OpenAIRE

    Mandell, Mercedes Susan; Lindenfeld, JoAnn; Tsou, Mei-Yung; Zimmerman, Michael

    2008-01-01

    Physicians previously thought that heart disease was rare in patients with end stage liver disease. However, recent evidence shows that the prevalence of ischemic heart disease and cardiomyopathy is increased in transplant candidates compared to most other surgical candidates. Investigators estimate that up to 26% of all liver transplant candidates have at least one critical coronary artery stenosis and that at least half of these patients will die perioperatively of cardiac complications. Ca...

  2. Newly identified YSO candidates towards LDN 1188

    Science.gov (United States)

    Marton , G.; Verebélyi, E.; Kiss, Cs.; Smidla, J.

    2013-11-01

    We present an analysis of young stellar object (YSO) candidates towards the LDN 1188 molecular cloud. The YSO candidates were selected from the WISE all-sky catalogue, based on a statistical method. We found 601 candidates in the region, and classified them as Class I, Flat, and Class II YSOs. Groups were identified and described with the Minimal Spanning Tree (MST) method. Previously identified molecular cores show evidence of ongoing star formation at different stages throughout the cloud complex.

  3. Giotto-spacecraft charging due to impact generated plasma in the presence of dielectric materials

    Science.gov (United States)

    Thiemann, H.; Schunk, R. W.; Singh, N.; Grard, R.

    1987-01-01

    The charging effects of a conducting/dielectric model spacecraft in the impact induced plasma environment are contrasted. The results of dynamic model calculations indicate larger charging times and higher positive spacecraft potentials for a conducting/dielectric spacecraft. The potential and particle distributions around the spacecraft differ quantitatively and qualitatively in both cases.

  4. Flight System Implementation of the Spacecraft Occulter System for Theia

    Science.gov (United States)

    Tenerelli, Domenick; Theia

    2009-01-01

    The objective of the Theia program is to characterize Earth-like planets around nearby stars. Theia utilizes two formation-flying spacecraft in an L2 orbit - an observatory and a free flying occulter. Characterization involves looking for signs of life by observing molecular signatures and the presence of water vapor. A free flying occulter spacecraft provides starlight suppression by blocking the starlight while allowing planet light to pass. A diffraction limited monolithic optical telescope is provided for observing planet light passed by the occulter spacecraft. The occulter spacecraft and observatory are flown with a separation of 38, 700 km to 72,000 km (depending on telescope aperture). The Theia system design greatly simplifies design, manufacturing, modeling, and testing requirements compared to a stand-alone high performance internal coronagraph. Design advantages include having thermal/mechanical specifications approaching those of a conventional telescope requiring minimal actuator count. Standard materials and manufacturing approaches apply. End-to-end testing and facilities requirements are standard. The occulter is comprised of up to 30 petals constructed of a dimensionally stable material. Each petal is structurally reinforced for ground handling and testing purposes. An electro-mechanically actuated deployment utilizes standard space qualified mechanism designs to achieve up to a 50m deployed diameter. Multiple layers ensure performance over 5 years of micro-meteroid degradation. The occulter spacecraft is a modular design built of dimensionally stable composite material with 6 bays mounted to a propulsion sub-assembly. The occulter spacecraft uses ion thrusters to achieve its required delta-V over its lifetime and to maintain a position tolerance of 1 m with respect to the observatory. A traditional reaction wheel system is used to maintain orientation. The occulter and occulter spacecraft are compatible with the Atlas 5 launch vehicle.

  5. Status of the Stardust ISPE and the Origin of Four Interstellar Dust Candidates

    Science.gov (United States)

    Westphal, A. J.; Allen, C.; Ansari, A.; Bajt, S.; Bastien, R. S.; Bassim, N.; Bechtel, H. A.; Borg, J.; Brenker, F. E.; Bridges, J.; Brownlee, D. E.; Burchell, M.; Burghammer, M.; Butterworth, A. L.; Changela, H.; Cloetens, P.; Davis, A. M.; Floss, C.; Flynn, G.; Fougeray, P.; Frank, D.; Gainsforth, Z.; Gruen, E.; Sandford, S. A.; Zolensky, M. E.

    2012-01-01

    Some bulk properties of interstellar dust are known through infrared and X-ray observations of the interstellar medium. However, the properties of individual interstellar dust particles are largely unconstrained, so it is not known whether individual interstellar dust particles can be definitively distinguished from interplanetary dust particles in the Stardust Interstellar Dust Collector (SIDC) based only on chemical, mineralogical or isotopic analyses. It was therefore understood from the beginning of the Stardust Interstellar Preliminary Examination (ISPE) that identification of interstellar dust candidates would rest on three criteria - broad consistency with known extraterrestrial materials, inconsistency with an origin as secondary ejecta from impacts on the spacecraft, and consistency, in a statistical sense, of observed dynamical properties - that is, trajectory and capture speed - with an origin in the interstellar dust stream. Here we quantitatively test four interstellar dust candidates, reported previously [1], against these criteria.

  6. Improved Spacecraft Materials for Radiation Protection

    Science.gov (United States)

    Wilson, John W.; Cucinotta, Francis A.; Tripathi, Ram K.; Clowdsley, M. S.; Shinn, J. L.; Singleterry, Robert C., Jr.; Thibeault, Sheila Ann; Kim, M.-H. Y.; Heinbockel, John H.; Badhwar, Gautam D.

    2001-01-01

    Sv limit for the exposure of the blood forming organs (this limit is strictly for LEO but can be used as a guideline for the Mars mission analysis). The current estimates require aluminum shield thicknesses above 50 g/sq cm., which is impractical. In such a heavily shielded vehicle, the neutrons produced throughout the vehicle also contribute significantly to the exposure and this demands greater care in describing the angular dependence of secondary particle production processes. As such the continued testing of databases and transport procedures in laboratory and spaceflight experiments has continued. This has been the focus of much of the last year's activity and has resulted in improved neutron prediction capability. These new methods have also improved our understanding of the surface environment of Mars. The Mars 2003 NRA HEDS related surface science requirements were driven by the need to validate predictions on the upward flux of neutrons produced in the Martian regolith and bedrock made by the codes developed under this project. The codes used in the surface environment definition are also being used to look at in situ resources for the development of construction material for Martian surface facilities. For example, synthesis of polyimides and polyethylene as binders of regolith for developing basic structural elements has been studied and targets built for accelerator beam testing of radiation shielding properties. Preliminary mechanical tests have also been promising. Improved spacecraft materials have been identified (using the criteria reported by this project at the last conference) as potentially important for future shielding materials. These are liquid hydrogen, hydrogenated nanofibers, liquid methane, LiH, Polyethylene, Polysulfone, and Polyetherimide (in order of decreasing shield performance). Some of the materials are multifunctional and are required for other onboard systems. We are currently preparing software for trade studies with these materials

  7. Undercover Stars Among Exoplanet Candidates

    Science.gov (United States)

    2005-03-01

    events by monitoring the brightness of a very large number of stars over extended time intervals. During the past years, it has also included a search for periodic, very shallow "dips" in the brightness of stars, caused by the regular transit of small orbiting objects (small stars, brown dwarfs [2] or Jupiter-size planets). The OGLE team has since announced 177 "planetary transit candidates" from their survey of several hundred thousand stars in three southern sky fields, one in the direction of the Galactic Centre, another within the Carina constellation and the third within the Centaurus/Musca constellations. The nature of the transiting object can however only be established by subsequent radial-velocity observations of the parent star. The size of the velocity variations (the amplitude) is directly related to the mass of the companion object and therefore allows discrimination between stars and planets as the cause of the observed brightness "dip". A Bonanza of Low-Mass Stars An international team of astronomers [3] has made use of the 8.2-m VLT Kueyen telescope for this work. Profiting from the multiplex capacity of the FLAMES/UVES facility that permits to obtain high-resolution spectra of up to 8 objects simultaneously, they have looked at 60 OGLE transit candidate stars, measuring their radial velocities with an accuracy of about 50 m/s [4]. This ambitious programme has so far resulted in the discovery of five new transiting exoplanets (see, e.g., ESO PR 11/04 for the announcement of two of those). Most of the other transit candidates identified by OGLE have turned out to be eclipsing binaries, that is, in most cases common, small and low-mass stars passing in front of a solar-like star. This additional wealth of data on small and light stars is a real bonanza for the astronomers. Constraining the Relation Between Mass and Radius Low-mass stars are exceptionally interesting objects, also because the physical conditions in their interiors have much in common with

  8. 28 CFR 105.12 - Notification for candidates eligible for expedited processing.

    Science.gov (United States)

    2010-07-01

    ... Department: (1) The full name of the candidate; (2) A unique student identification number created by the... electronic mail. Only notifications sent from an electronic mail address registered as a Provider will be... passport number. The Provider must be able to reference these records by the unique student...

  9. Development of a Complimentary Low Temperature Decontamination Technique for Spacecraft Materials

    Science.gov (United States)

    Pottage, Thomas; Bennett, Allan; Walker, James; Fowler, Chantal; Weber, Christina; Rohr, Thomas; Kminek, Gerhard

    Dry heat microbial reduction (DHMR) is one of the current processes used to ensure that the microbial burden of a spacecraft lander meets the predetermined levels set out within the COSPAR policy regarding planetary protection. DHMR involves heating the craft or compo-nents to approximately 110-125C for over 6-30hrs, and was previously used to decontaminate the entire Viking lander spacecraft and parts of almost all other spacecrafts sent to Mars after-wards. This process, whilst proving effective and reproducible is not compatible with the some highly sensitive sensor and electronic components of a modern spacecraft. For these components an alternative method for low temperature decontamination needs to be identified. The Health Protection Agency, UK, investigated three gaseous decontamination technologies in a project funded by European Space Agency. These technologies consisted of two hydrogen peroxide technologies (Vapour Hydrogen Peroxide, Steris Inc. and Hydrogen Peroxide Vapour, Bioquell Ltd.) and one chlorine dioxide (ClorDiSys) system. The technologies were chosen after a comprehensive literature study identified them as the most suitable technologies for the decontamination process. An environmental chamber (20m3 ) was used as the test chamber to expose two commercially available biological indicators, three naturally occurring organisms chosen by ESA and a range of spacecraft materials to each of the technologies. The commercial biological indicators, Bacil-lus atrophaeus and Geobacillus sterothermophilus, were exposed to 3 varying concentrations of each of the technologies in order to attempt to achieve a 6-log reduction in recoverable organ-isms. After these results were obtained the most efficacious cycle was chosen for each technology and the naturally occurring organisms and materials to be tested were exposed to three cy-cles. Whilst the microbial enumeration was completed at the HPA, material compatibility was undertaken at ESTEC and residue

  10. 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.

  11. Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking

    Directory of Open Access Journals (Sweden)

    Armstrong J. W.

    2006-01-01

    Full Text Available This paper discusses spacecraft Doppler tracking, the current-generation detector technology used in the low-frequency (~millihertz gravitational wave band. In the Doppler method the earth and a distant spacecraft act as free test masses with a ground-based precision Doppler tracking system continuously monitoring the earth-spacecraft relative dimensionless velocity $2 Delta v/c = Delta u/ u_0$, where $Delta u$ is the Doppler shift and $ u_0$ is the radio link carrier frequency. A gravitational wave having strain amplitude $h$ incident on the earth-spacecraft system causes perturbations of order $h$ in the time series of $Delta u/ u_0$. Unlike other detectors, the ~1-10 AU earth-spacecraft separation makes the detector large compared with millihertz-band gravitational wavelengths, and thus times-of-flight of signals and radio waves through the apparatus are important. A burst signal, for example, is time-resolved into a characteristic signature: three discrete events in the Doppler time series. I discuss here the principles of operation of this detector (emphasizing transfer functions of gravitational wave signals and the principal noises to the Doppler time series, some data analysis techniques, experiments to date, and illustrations of sensitivity and current detector performance. I conclude with a discussion of how gravitational wave sensitivity can be improved in the low-frequency band.

  12. Multi-Spacecraft Observations of Recurrent 3He-Rich Solar Energetic Particles

    CERN Document Server

    Bucik, R; Mall, U; Korth, A; Mason, G M; Gomez-Herrero, R

    2014-01-01

    We study the origin of 3He-rich solar energetic particles (<1 MeV/nucleon) that are observed consecutively on STEREO-B, ACE, and STEREO-A spacecraft when they are separated in heliolongitude by more than 90{\\deg}. The 3He-rich period on STEREO-B and STEREO-A commences on 2011 July 1 and 2011 July 16, respectively. The ACE 3He-rich period consists of two sub-events starting on 2011 July 7 and 2011 July 9. We associate the STEREO-B July 1 and ACE July 7 3He-rich events with the same sizeable active region producing X-ray flares accompanied by prompt electron events, when it was near the west solar limb as seen from the respective spacecraft. The ACE July 9 and STEREO-A July 16 events were dispersionless with enormous 3He enrichment, lacking solar energetic electrons and occurring in corotating interaction regions. We associate these events with a small, recently emerged active region near the border of a low-latitude coronal hole that produced numerous jet-like emissions temporally correlated with type III r...

  13. Multi-spacecraft observations of wide-spread SEP events and unexpected energetic particle distributions

    Science.gov (United States)

    Dresing, N.; Gómez-Herrero, R.; Klassen, A.; Kartavykh, Y.; Droege, W.; Heber, B.; Klecker, B.

    2011-12-01

    With the end of 2009 the solar cycle 23 came to an end with solar activity increasing again. The meanwhile well separated two STEREO spacecraft in combination with further observers located at L1 provide an unique platform to investigate the longitudinal spread of energetic particles at 1 AU. In some cases the angular distribution was even far above 100 degrees as for instance in the January 17, 2010 SEP event, which shows energetic electrons and protons spreading almost all around the Sun. Large time delays between the flare and electron onsets at the spacecraft of about one hour as well as a lack of anisotropies and velocity dispersion are accompanying observations. Together with results from a 3D propagation model perpendicular diffusion is suggested to play a major role in understanding the observed particle distribution. Another example presented is the May 5, 2009 SEP event which was strongest observed at STEREO A, weaker at Earth and not by STEREO B. Multi-point radio measurements together with EUVI observations by STEREO B support an eastern source as seen from STEREO B for this event. However in-situ particle time-intensity profiles and anisotropies resemble a well connected source, rather than the eastern AR separated by ~100 degrees from the footpoint of STEREO A. These contradictory observations probably indicate an extremely asymmetric particle distribution.

  14. Special Education Teacher Candidate Assessment: A Review

    Science.gov (United States)

    McCall, Zach; McHatton, Patricia Alvarez; Shealey, Monika Williams

    2014-01-01

    Teacher preparation has been under intense scrutiny in recent years. In order for preparation of special education teacher candidates to remain viable, candidate assessment practices must apply practices identified in the extant literature base, while special education teacher education researchers must extend this base with rigorous efforts to…

  15. 11 CFR 110.13 - Candidate debates.

    Science.gov (United States)

    2010-01-01

    ... political parties may stage candidate debates in accordance with this section and 11 CFR 114.4(f). (2... also cover or carry candidate debates in accordance with 11 CFR part 100, subparts B and C and part 100... CFR 114.4(f), provided that they are not owned or controlled by a political party, political...

  16. Event display of a H -> 4e candidate event

    CERN Multimedia

    ATLAS, Collaboration

    2012-01-01

    Event display (side view) of a H -> 4e candidate event with m(4l) = 124.5 (124.6) GeV without (with) Z mass constraint. The masses of the lepton pairs are 70.6 GeV and 44.7 GeV. The event was recorded by ATLAS on 18-May-2012, 20:28:11 CEST in run number 203602 as event number 82614360. The tracks of the two electron pairs are colored red and blue, respectively. Electron clusters in the LAr calorimeter are colored darkgreen. The three displays on the right-hand side show the r-phi view of the event (top), a zoom into the vertex region, indicating that the 4 electrons originate from the same primary vertex (middle), and a Lego plot indicating the amount of transverse energy Et measured in the calorimeters (bottom).

  17. Distributed microprocessors for spacecraft control and data handling

    Science.gov (United States)

    Lesh, F.; Lecoq, P.

    1976-01-01

    The Unified Data System (UDS) group at JPL is attempting to reduce total mission costs by designing a spacecraft data system which takes advantage of the natural and historical partitioning of a spacecraft into subsystems. Each subsystem is assigned a microprocessor which needs just enough capability to control the sensors and actuators of that subsystem, collect its data and maintain time synchronization with the rest of the spacecraft. The resulting distributed system avoids many of the overhead costs of a single centralized multi-processing system. To minimize complexity and therefore minimize total mission costs, a variety of standards and restrictions are imposed on the design of hardware, software, and communications. Articulation of these standards and restrictions is a major benefit deriving from the UDS program.

  18. Vibration Isolation and Stabilization System for Spacecraft Exercise Treadmill Devices

    Science.gov (United States)

    Fialho, Ian; Tyer, Craig; Murphy, Bryan; Cotter, Paul; Thampi, Sreekumar

    2011-01-01

    A novel, passive system has been developed for isolating an exercise treadmill device from a spacecraft in a zero-G environment. The Treadmill 2 Vibration Isolation and Stabilization System (T2-VIS) mechanically isolates the exercise treadmill from the spacecraft/space station, thereby eliminating the detrimental effect that high impact loads generated during walking/running would have on the spacecraft structure and sensitive microgravity science experiments. This design uses a second stage spring, in series with the first stage, to achieve an order of magnitude higher exercise- frequency isolation than conventional systems have done, while maintaining desirable low-frequency stability performance. This novel isolator design, in conjunction with appropriately configured treadmill platform inertia properties, has been shown (by on-orbit zero-G testing onboard the International Space Station) to deliver exceedingly high levels of isolation/ stability performance.

  19. Kalman Filter Estimation of Spinning Spacecraft Attitude using Markley Variables

    Science.gov (United States)

    Sedlak, Joseph E.; Harman, Richard

    2004-01-01

    There are several different ways to represent spacecraft attitude and its time rate of change. For spinning or momentum-biased spacecraft, one particular representation has been put forward as a superior parameterization for numerical integration. Markley has demonstrated that these new variables have fewer rapidly varying elements for spinning spacecraft than other commonly used representations and provide advantages when integrating the equations of motion. The current work demonstrates how a Kalman filter can be devised to estimate the attitude using these new variables. The seven Markley variables are subject to one constraint condition, making the error covariance matrix singular. The filter design presented here explicitly accounts for this constraint by using a six-component error state in the filter update step. The reduced dimension error state is unconstrained and its covariance matrix is nonsingular.

  20. Efficient Spectral Endmember Detection Onboard the EO-1 Spacecraft

    Science.gov (United States)

    Bornstein, Ben; Thompson, David R.; Tran, Daniel; Bue, Brian; Chien, Steve; Castano, Rebecca

    2011-01-01

    Spaceflight and planetary exploration place severe constraints on the available bandwidth for downlinking large hyperspectral images. In addition, communications with spacecraft often occur intermittently, so mission-relevant hyperspectral data must wait for analysis on the ground before it can inform spacecraft activity planning. Onboard endmember detection can help alleviate these problems. It enables novelty detection and target identification for scheduling follow-up activities such as additional observation by narrow field of view instruments. Additionally, endmember analysis can facilitate data summary for downlink. This work describes a planned experiment of selective downlink by the EO-1 autonomous spacecraft. Here an efficient superpixel endmember detection algorithm keeps to the limited computational constraints of the flight processor. Tests suggest the procedure could enable significant improvements in downlink efficiency.

  1. Energy-based robust controller design for flexible spacecraft

    Institute of Scientific and Technical Information of China (English)

    Shuzhi Sam GE; Tong Heng LEE; Fan HONG; Cher Hiang GOH

    2004-01-01

    This paper presents a class of non-model-based position controllers for a kind of flexible spacecraft. With the controllers, one can achieve not only the closed-loop stability of the original distributed parameter system, but also the asymptotic stability of the truncated system, which is obtained through representing the deflection of the appendage by an arbitrary finite number of flexible modes. The system dynamics are not explicitly involved in the controller design and stability proof. Instead, only a very basic system energy relationship of the flexible spacecraft is utilized. The controllers possess several remarkable advantages over the traditional model-based ones. Numerical simulations are carded out on a kind of spacecraft with one flexible appendage and satisfactory results are obtained.

  2. Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants. Volume 5

    Science.gov (United States)

    2008-01-01

    To protect space crews from air contaminants, NASA requested that the National Research Council (NRC) provide guidance for developing spacecraft maximum allowable concentrations (SMACs) and review NASA's development of exposure guidelines for specific chemicals. The NRC convened the Committee on Spacecraft Exposure Guidelines to address this task. The committee published Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants (NRC 1992). The reason for the review of chemicals in Volume 5 is that many of them have not been examined for more than 10 years, and new research necessitates examining the documents to ensure that they reflect current knowledge. New knowledge can be in the form of toxicologic data or in the application of new approaches for analysis of available data. In addition, because NASA anticipates longer space missions beyond low Earth orbit, SMACs for 1,000-d exposures have also been developed.

  3. New Strategy of IPACS Design and Energy Management for Spacecrafts

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-rui

    2006-01-01

    The design problem of an integrated power and attitude control system (IPACS) for spacecrafts is investigated. A Lyapunov-typed IPACS controller is designed for a spacecraft equipped with 4 flywheels (3 orthogonal + 1 skew). This controller keeps in the nonlinear properties of original systems, so the control result can be more precise. A control law of the flywheels is also proposed to accomplish the attitude control and energy storage simultaneously. Aiming at the limitations existing in the power conversion characteristic and the wheel's motor, a new strategy of energy management is proposed. The strategy can not only make the charged/discharged energy reaching balance in each orbital period, but also sufficiently utilize the power provided by the solar arrays. Therefore, the size and mass of solar arrays can be decreased, and the cost of spacecraft can be economized. A simulation example illustrates the validity of the designed IPACS.

  4. Using IoT Device Technology in Spacecraft Checkout Systems

    Science.gov (United States)

    Plummer, Chris

    2015-09-01

    The Internet of Things (IoT) has become a common theme in both the technical and popular press in recent years because many of the enabling technologies that are required to make IoT a reality have now matured. Those technologies are revolutionising the way industrial systems and products are developed because they offer significant advantages over older technologies. This paper looks at how IoT device technology can be used in spacecraft checkout systems to achieve smaller, more capable, and more scalable solutions than are currently available. It covers the use of IoT device technology for classical spacecraft test systems as well as for hardware-in-the-loop simulation systems used to support spacecraft checkout.

  5. Vision Based Navigation Sensors for Spacecraft Rendezvous and Docking

    DEFF Research Database (Denmark)

    Benn, Mathias

    of this constellation, providing both position and pose information for the Target vehicle. This dissertation will describe the study, implementation and verification methods that has led to the realization of this optical Vision Based Sensor (VBS), which is used on the PRISMA mission. On June 15th 2010 the PRISMA...... active spacecraft together providing the global positioning service dubbed GPS. However, several other present missions provide augmented performances based on multi space segment configuration, e.g. the GRACE twin spacecraft form together the world's hitherto most accurate gravitometer, which has....... Denmark has, with DTUs design of the Swarm mission, ESAs next Earth Observation Programme magnetic mapping mission, and DTUs participation in GRACE, ELISA and Alsat2, a leading role in designing and verifying sensor systems for this new class of spacecraft. The Swedish led PRISMA mission...

  6. Spacecraft dynamics due to elastic ring antenna deployment

    Science.gov (United States)

    Makarov, Alexandr L.; Khoroshilov, Viktor S.; Zakrzhevskii, Alexandr E.

    2011-09-01

    In this paper the dynamics of a spacecraft with a system of stabilization out-of-operation is studied. The deployment of the ring flexible antenna is performed after placing the spacecraft into orbit and damping the initially undesired rotations by a special jet-propelled system. Basically the antenna is a pre-stressed tape reeled on a special drum. Deploying from the drum, the tape takes the shape of an elastic ring of 30 m in diameter. The objective of the study is the mechanical and computational modelling of the spacecraft dynamics. The equations of motion are derived in Lagrangian form. Numerical simulations of operational mode of the system are performed. As it is shown in main result, which restrictions must be imposed on parameters of the process of deployment for maintenance of the shape of the deployed design.

  7. Discovery of optical candidate supernova remnants in Sagittarius

    Science.gov (United States)

    Alikakos, J.; Boumis, P.; Christopoulou, P. E.; Goudis, C. D.

    2012-08-01

    During an [O III] survey of planetary nebulae, we identified a region in Sagittarius containing several candidate supernova remants (SNRs) and obtained deep optical narrow-band images and spectra to explore their nature. We obtained images of the area of interest by acquiring observations in the emission lines of Hα + [N II], [S II] and [O III]. The resulting mosaic covers an area of 1.4° × 1.0°, where both filamentary and diffuse emission was discovered, suggesting that there is more than one SNR in the area. Deep long-slit spectra were also taken of eight different regions. Both the flux-calibrated images and the spectra show that the emission from the filamentary structures originates from shock-heated gas, while the photo-ionization mechanism is responsible for the diffuse emission. Part of the optical emission is found to be correlated with the radio at 4850 MHz suggesting that they are related, while the infrared emission found in the area at 12 μm and 22 μm marginally correlates with the optical. The presence of the [O III] emission line in one of the candidate SNRs implies that the shock velocities in the interstellar "clouds" are between 120 km s-1 and 200 km s-1, while its absence in the other candidate SNRs indicates that the shock velocities there are slower. For all candidate remnants, the [S II] λλ 6716/6731 ratio indicates that the electron densities are below 240 cm-3, while the Hα emission is measured to be between 0.6 and 41 × 10-17 erg s-1 cm-2 arcsec-2. The existence of eight pulsars within 1.5° of the center of the candidate SNRs also implies that there are many SNRs in the area as well as that the detected optical emission could be part of a number of supernovae explosions.

  8. Monitoring Spacecraft Telemetry Via Optical or RF Link

    Science.gov (United States)

    Fielhauer, K. B.; Boone, B. G.

    2011-01-01

    A patent disclosure document discusses a photonic method for connecting a spacecraft with a launch vehicle upper-stage telemetry system as a means for monitoring a spacecraft fs health and status during and right after separation and deployment. This method also provides an efficient opto-coupled capability for prelaunch built-in-test (BIT) on the ground to enable more efficient and timely integration, preflight checkout, and a means to obviate any local EMI (electromagnetic interference) during integration and test. Additional utility can be envisioned for BIT on other platforms, such as the International Space Station (ISS). The photonic telemetry system implements an optical free-space link with a divergent laser transmitter beam spoiled over a significant cone angle to accommodate changes in spacecraft position without having to angle track it during deployment. Since the spacecraft may lose attitude control and tumble during deployment, the transmitted laser beam interrogates any one of several low-profile meso-scale retro-reflective spatial light modulators (SLMs) deployed over the surface of the spacecraft. The return signal beam, modulated by the SLMs, contains health, status, and attitude information received back at the launch vehicle. Very compact low-power opto-coupler technology already exists for the received signal (requiring relatively low bandwidths, e.g., .200 kbps) to enable transfer to a forward pass RF relay from the launch vehicle to TDRSS (Tracking and Data Relay Satellite System) or another recipient. The link would be active during separation and post-separation to monitor spacecraft health, status, attitude, or other data inventories until attitude recovery and ground control can be re-established. An optical link would not interfere with the existing upper stage telemetry and beacon systems, thus meeting launch vehicle EMI environmental constraints.

  9. Using modified ballistic limit equations in spacecraft risk assessments

    Science.gov (United States)

    Schonberg, William P.

    2016-09-01

    The fundamental components of any meteoroid/orbital debris (MOD) risk assessment calculation are environment models, damage response predictor equations, and failure criteria. In the case of a spacecraft operating in low earth orbit, the response predictor equation typically takes the form of a ballistic limit equation (BLE) that defines the threshold particle sizes that cause failure of a spacecraft wall or component. Spacecraft risk assessments often call for BLEs for spacecraft components that do not exist. In such cases, it is a common procedure to use an existing BLE after first equivalencing the actual materials and/or wall thicknesses to the materials that were used in the development of the existing BLE. The question naturally arises regarding how close are the predictions of such an 'adapted BLE' to the response characteristics of the actual materials/wall configurations under high speed projectile impacts. This paper presents the results of a study that compared the predictions of a commonly used BLE when adapted to the Soyuz OM wall configuration against those of a new BLE that was developed specifically for that Soyuz wall configuration. It was found that the critical projectile diameters predicted by the new Soyuz OM wall BLE can exceed those predicted by the adapted use of the existing BLE by as much as 50% of the existing BLE values. Thus, using the adapted version of the existing BLE in this particular case would contribute to a more conservative value of assessed risk. If the same trends were to hold true for other spacecraft wall configurations, then it is also possible that using existing BLEs, even after they have been adjusted for differences in materials, etc., may result in predictions of smaller critical diameters (i.e., increased assessed risk) than would using BLEs purposely developed for actual spacecraft configurations of interest.

  10. 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

  11. Laboratory Spacecraft Data Processing and Instrument Autonomy: AOSAT as Testbed

    Science.gov (United States)

    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

  12. Active Solar Sail Designs for Chip-Scale Spacecraft

    OpenAIRE

    Weis, Lorraine; Peck, Mason

    2014-01-01

    Centimeter-scale spacecraft, known as ”Chipsats,” have very high surface-area-to-mass ratios, which accentuates solar radiation pressure (SRP) effects. In contrast to traditional. large solar sails, chip-scale solar sails have the potential to be highly agile in terms of attitude because of their structural rigidity and low moments of inertia. This ability to easily reorient a solar sail greatly expands the orbits that a solar-sail spacecraft can achieve. Solar sail actuation through electroc...

  13. Application of an onboard processor to the OAO C spacecraft

    Science.gov (United States)

    Stewart, W. N.; Hartenstein, R. G.; Trevathan, C.

    1972-01-01

    The design of a stored program computer for spacecraft use and its application on the fourth Orbiting Astronomical Observatory (OAO) is reported. The computer is a medium scale, parallel machine with a memory capacity of 16384 words of 18 bits each. It possesses a comprehensive instruction repertoire and operates on 45 W of power (including the dc-to-dc converter). The machine operates at a 500-kHz rate and executes an add instruction in 10 microseconds. Its primary functions on OAO C will be auxiliary command storage, spacecraft monitoring and malfunction reporting, data compression and status summary, and possible performance of emergency corrective action for certain anomalous situations.

  14. Spacecraft motion analysis about rapid rotating small body

    Institute of Scientific and Technical Information of China (English)

    史雪岩; 崔祜涛; 崔平远; 栾恩杰

    2003-01-01

    The orbital dynamics equation of a spacecraft around an irregular sphere small body is established based on the small body' s gravitational potential approximated with a tri-axial ellipsoid. According to the Jacobi integral constant, the spacecraft zero-velocity curves in the vicinity of the small body is described and feasible motion region is analyzed. The limited condition and the periapsis radius corresponding to different eccentricity against impact surface are presented. The stability of direct and retrograde equator orbits is analyzed based on the perturbation solutions of mean orbit elements.

  15. Effects of directed and kinetic energy weapons on spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Fraas, A P

    1986-12-01

    The characteristics of the various directed energy beams are reviewed, and their damaging effects on typical materials are examined for a wide range of energy pulse intensities and durations. Representative cases are surveyed, and charts are presented to indicate regions in which damage to spacecraft structures, particularly radiators for power plants, would be likely. The effects of kinetic energy weapons, such as bird-shot, are similarly examined. The charts are then applied to evaluate the effectiveness of various measures designed to reduce the vulnerability of spacecraft components, particularly nuclear electric power plants.

  16. Multimode attitude and orbit control for the Atmosphere Explorer spacecraft

    Science.gov (United States)

    Stewart, B.

    1975-01-01

    The orbit profile for the Atmosphere Explorer requires a velocity adjust capability of 2000 ft/sec/sec and individual maneuvers of up to 24 ft/sec in magnitude. This requirement is met by a monopropellant hydrazine propulsion subsystem which also provides, by virtue of the tank arrangement, a means of adjusting the spacecraft center of mass in orbit, thereby minimizing external disturbance torques. The attitude control subsystem is of the momentum bias type. A large internal flywheel furnishes gyroscopic stiffness and permits rapid changes in operating mode (despun to spinning mode) by controlled interchange of momentum between the flywheel and the spacecraft main body.

  17. Active Control of Solar Array Dynamics During Spacecraft Maneuvers

    Science.gov (United States)

    Ross, Brant A.; Woo, Nelson; Kraft, Thomas G.; Blandino, Joseph R.

    2016-01-01

    Recent NASA mission plans require spacecraft to undergo potentially significant maneuvers (or dynamic loading events) with large solar arrays deployed. Therefore there is an increased need to understand and possibly control the nonlinear dynamics in the spacecraft system during such maneuvers. The development of a nonlinear controller is described. The utility of using a nonlinear controller to reduce forces and motion in a solar array wing during a loading event is demonstrated. The result is dramatic reductions in system forces and motion during a 10 second loading event. A motion curve derived from the simulation with the closed loop controller is used to obtain similar benefits with a simpler motion control approach.

  18. Research on Cable Assembly Technology Facing Tridimention Layout in Spacecraft

    Science.gov (United States)

    Song, Xiaohui; Liu, Zhe; Wang, Zaicheng; Zhang, Yidan; Zhang, Jie; Liu, Zhibin

    According to the requirement for cables tridimensional layout in spacecraft, the research on new transmission line support (NTLS) is carried out. NTLS is namely T support. Based on the analysis of NTLS's physical parameters, the scheme of cable installing is established. Experimentations of statics and vibration prove the feasibility and dependability of the scheme. The results of experimentation indicate that the scheme of cable installing on T support is reasonable along with the requirement of cables tridimensional layout is satisfied. Therefore the efficiency of spacecraft assembly and integration is greatly enhanced.

  19. Adaptive control for autonomous rendezvous of spacecraft on elliptical orbit

    Institute of Scientific and Technical Information of China (English)

    Shan Lu; Shijie Xu

    2009-01-01

    A strategy for spacecraft autonomous rendezvous on an elliptical orbit in situation of no orbit information is developed. Lawden equation is used to describe relative motion of two spacecraft. Then an adaptive gain factor is introduced, and an adaptive control law for autonomous rendezvous on the elliptical orbit is designed using Lyapunov approach. The relative motion is proved to be ultimately bounded under this control law, and the final relative position error can achieve the expected magnitude. Simulation results indicate that the adaptive control law can realize autonomous rendezvous on the elliptical orbit with relative state information only.

  20. Microbiological burden on the surfaces of Explorer 33 spacecraft.

    Science.gov (United States)

    Powers, E M

    1967-09-01

    The Explorer XXXIII Spacecraft (Anchored Interplanetary Monitoring Platform, or AIMP) was decontaminated to prevent gross contamination of the moon with terrestrial microorganisms. Assay of the total spacecraft surface before and after decontamination showed that the decontamination procedure reduced the viable microbiological burden from 1.40 x 10(6) to 3.60 x 10(4). However, assembly of parts which were not decontaminated for engineering reasons or were not assembled under cleanroom conditions increased the viable microbial burden at the time of launch to 2.62 x 10(5).

  1. Corrugation Stuffed Shield for Spacecraft and Its Performance

    Institute of Scientific and Technical Information of China (English)

    LIU You-ying; WANG Hai-fu

    2006-01-01

    A corrugation stuffed shield system protecting spacecrafts against meteoroid and orbital debris (M/OD) is presented. The semi-empirical ballistic limit equations (BLEs)defining the protection capability of the shield system are given, an d the shielding performance is also discussed. The corrugation stuffed shield (CSS) is more effective than stuffed Whipple shield for M/OD protection,and its shielding performance will be improved significantly as increasing the impact angle. Orbital debris up to 1cm in diameter can be shielded effectively as increasing the impact angle to 25° at the corrugated angle of 30°. The results are significant to spacecraft design.

  2. Statistical Evaluation of Molecular Contamination During Spacecraft Thermal Vacuum Test

    Science.gov (United States)

    Chen, Philip; Hedgeland, Randy; Montoya, Alex; Roman-Velazquez, Juan; Dunn, Jamie; Colony, Joe; Petitto, Joseph

    1999-01-01

    The purpose of this paper is to evaluate the statistical molecular contamination data with a goal to improve spacecraft contamination control. The statistical data was generated in typical thermal vacuum tests at the National Aeronautics and Space Administration, Goddard Space Flight Center (GSFC). The magnitude of material outgassing was measured using a Quartz Crystal Microbalance (QCNO device during the test. A solvent rinse sample was taken at the conclusion of each test. Then detailed qualitative and quantitative measurements were obtained through chemical analyses. All data used in this study encompassed numerous spacecraft tests in recent years.

  3. 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.

  4. CLIpSAT for Interplanetary Missions: Common Low-cost Interplanetary Spacecraft with Autonomy Technologies

    Science.gov (United States)

    Grasso, C.

    2015-10-01

    Blue Sun Enterprises, Inc. is creating a common deep space bus capable of a wide variety of Mars, asteroid, and comet science missions, observational missions in and near GEO, and interplanetary delivery missions. The spacecraft are modular and highly autonomous, featuring a common core and optional expansion for variable-sized science or commercial payloads. Initial spacecraft designs are targeted for Mars atmospheric science, a Phobos sample return mission, geosynchronous reconnaissance, and en-masse delivery of payloads using packetized propulsion modules. By combining design, build, and operations processes for these missions, the cost and effort for creating the bus is shared across a variety of initial missions, reducing overall costs. A CLIpSAT can be delivered to different orbits and still be able to reach interplanetary targets like Mars due to up to 14.5 km/sec of delta-V provided by its high-ISP Xenon ion thruster(s). A 6U version of the spacecraft form fits PPOD-standard deployment systems, with up to 9 km/s of delta-V. A larger 12-U (with the addition of an expansion module) enables higher overall delta-V, and has the ability to jettison the expansion module and return to the Earth-Moon system from Mars orbit with the main spacecraft. CLIpSAT utilizes radiation-hardened electronics and RF equipment, 140+ We of power at earth (60 We at Mars), a compact navigation camera that doubles as a science imager, and communications of 2000 bps from Mars to the DSN via X-band. This bus could form the cornerstone of a large number asteroid survey projects, comet intercept missions, and planetary observation missions. The TugBot architecture uses groups of CLIpSATs attached to payloads lacking innate high-delta-V propulsion. The TugBots use coordinated trajectory following by each individual spacecraft to move the payload to the desired orbit - for example, a defense asset might be moved from GEO to lunar transfer orbit in order to protect and hide it, then returned

  5. Mechanical Properties of Fuel Cladding Candidate Alloys for Canadian SCWR Concept

    Science.gov (United States)

    Xu, Su; Amirkhiz, Babak Shalchi

    2016-02-01

    An assessment of tensile and creep of five representative candidate fuel cladding alloys for a Canadian Gen IV super-critical water reactor concept was performed based on database development work and complementary experiments including a transmission electron microscopy study of creep in stainless steels. The limiting property would be creep strength of candidate alloys for the "free-standing" fuel cladding design with a hot-spot peak temperature range of 1073-1123 K (800-850°C).

  6. Electron cross talk and asymmetric electron distributions near the Earth's bowshock

    Directory of Open Access Journals (Sweden)

    J. J. Mitchell

    2012-03-01

    Full Text Available Electron distributions in the magnetosheath display a number of far from equilibrium features. It has been suggested that one factor influencing these distributions may be the large distances separating locations at which electrons with different energies and pitch angles must cross the bowshock in order to reach a given point in the magnetosheath. The overall heating requirements at these distant locations depends strongly on the shock geometry. In the absence of collisions or other isotropization processes this suggests that the convolution of electrons arriving from different locations should give rise to asymmetries in the distribution functions. Moreover, such cross-talk could influence the relative electron to ion heating, rendering the shock heating problem intrinsically non-local in contrast to classic shock physics. Here, we study electron distributions measured simultaneously by the Plasma Electron and Current Experiment (PEACE on board the Cluster spacecraft and the Electrostatic Analyser (ESA on board THEMIS b during a time interval in which both the Cluster spacecraft and THEMIS b are in the magnetosheath, close to the bowshock, and during which the local magnetic field orientation makes it likely that electron trajectories may connect both spacecraft. We find that the relevant portions of the velocity distributions of such electrons measured by each spacecraft display remarkable similarities. We map trajectories of electrons arriving at each spacecraft back to the locations at which they crossed the bowshock, as a function of pitch angle and energy. We then use the Rankine-Hugoniot relations to estimate the heating of electrons and compare this with temperature asymmetries actually observed. We conclude that the electron distributions and temperatures in the magnetosheath depend heavily on non-local shock properties.

  7. Photo multiplier tubes candidates for the Cherenkov telescope array project

    International Nuclear Information System (INIS)

    Photo Multiplier Tubes (PMTs) are the most wide spread detectors for fast low-level light signals. They are commonly used as standard light sensors for camera systems in imaging atmospheric Cherenkov telescopes. Years ago, an improvement program for the PMT candidates for the Cherenkov Telescope Array (CTA) project was initialized with the companies Hamamatsu Photonics K.K. (Japan) and Electron Tubes Enterprises Ltd. (England). CTA is the next generation of imaging atmospheric Cherenkov telescopes for high energy gamma ray astrophysics. Therefore, we need PMTs with outstanding good parameters concerning quantum efficiency, pulse width, after-pulsing and transit time spread. The currently available ''super-bialkali'' PMTs show a peak Quantum Efficiency of 40% and have an enhanced collection efficiency of up to 95-98% for wavelengths≥400 nm. The pulse width averages around 3ns at a gain of 40000. Also, the after-pulsing for a set threshold level of ≥4 photo electrons is reduced down to 0,02%. We report on the measurement results of PMT R-12292-100 from Hamamatsu as the final version and the intermediate version PMT D569/3SA from Electron Tubes Enterprises as candidate PMTs for the CTA project.

  8. Motor/generator and electronic control considerations for energy storage flywheels

    Science.gov (United States)

    Nola, F. J.

    1984-01-01

    A spacecraft electric power supply system is described. Requirements of the system are to accelerate a momentum wheel to a fixed maximum speed when solar energy is available and to maintain a constant voltage on the spacecraft bus under varying loads when solar energy is not available. Candidate motor types, pulse width modulated current control systems, and efficiency considerations are discussed. In addition, the Lunar Roving Vehicle motors are described along with their respective efficiencies.

  9. Pi-Sat: A Low Cost Small Satellite and Distributed Spacecraft Mission System Test Platform

    Science.gov (United States)

    Cudmore, Alan

    2015-01-01

    Current technology and budget trends indicate a shift in satellite architectures from large, expensive single satellite missions, to small, low cost distributed spacecraft missions. At the center of this shift is the SmallSatCubesat architecture. The primary goal of the Pi-Sat project is to create a low cost, and easy to use Distributed Spacecraft Mission (DSM) test bed to facilitate the research and development of next-generation DSM technologies and concepts. This test bed also serves as a realistic software development platform for Small Satellite and Cubesat architectures. The Pi-Sat is based on the popular $35 Raspberry Pi single board computer featuring a 700Mhz ARM processor, 512MB of RAM, a flash memory card, and a wealth of IO options. The Raspberry Pi runs the Linux operating system and can easily run Code 582s Core Flight System flight software architecture. The low cost and high availability of the Raspberry Pi make it an ideal platform for a Distributed Spacecraft Mission and Cubesat software development. The Pi-Sat models currently include a Pi-Sat 1U Cube, a Pi-Sat Wireless Node, and a Pi-Sat Cubesat processor card.The Pi-Sat project takes advantage of many popular trends in the Maker community including low cost electronics, 3d printing, and rapid prototyping in order to provide a realistic platform for flight software testing, training, and technology development. The Pi-Sat has also provided fantastic hands on training opportunities for NASA summer interns and Pathways students.

  10. 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

  11. Event display of a H -> 4e candidate event

    CERN Multimedia

    ATLAS, Collaboration

    2012-01-01

    Event display of a H -> 4e candidate event with m(4l) = 124.5 (124.6) GeV without (with) Z mass constraint. The masses of the lepton pairs are 70.6 GeV and 44.7 GeV. The event was recorded by ATLAS on 18-May-2012, 20:28:11 CEST in run number 203602 as event number 82614360. Zoom into the tracking detector and the LAr calorimeter where its detailed structure is highlighted. The tracks and clusters of the two electron pairs are colored red and blue, respectively.

  12. Event display of a H -> 4e candidate event

    CERN Multimedia

    ATLAS, Collaboration

    2012-01-01

    Event display of a H -> 4e candidate event with m(4l) = 124.5 (124.6) GeV without (with) Z mass constraint. The masses of the lepton pairs are 70.6 GeV and 44.7 GeV. The event was recorded by ATLAS on 18-May-2012, 20:28:11 CEST in run number 203602 as event number 82614360. The tracks and clusters of the two electron pairs are colored red and blue, respectively.

  13. Event display of a H -> 4e candidate event

    CERN Multimedia

    ATLAS, Collaboration

    2012-01-01

    Event display of a H -> 4e candidate event with m(4l) = 124.5 (124.6) GeV without (with) Z mass constraint. The masses of the lepton pairs are 70.6 GeV and 44.7 GeV. The event was recorded by ATLAS on 18-May-2012, 20:28:11 CEST in run number 203602 as event number 82614360. Zoom into the tracking detector. The tracks and clusters of the two electron pairs are colored red and blue, respectively.

  14. Event display of a H -> 4e candidate event

    CERN Multimedia

    ATLAS, Collaboration

    2012-01-01

    Event display of a H -> 4e candidate event with m(4l) = 124.5 (124.6) GeV without (with) Z mass constraint. The masses of the lepton pairs are 70.6 GeV and 44.7 GeV. The event was recorded by ATLAS on 18-May-2012, 20:28:11 CEST in run number 203602 as event number 82614360. The tracks of the two electron pairs are colored red, the clusters in the LAr calorimeter are colored darkgreen.

  15. Autonomous spacecraft landing through human pre-attentive vision

    International Nuclear Information System (INIS)

    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)

  16. A modular electric power system test bed for small spacecraft

    Science.gov (United States)

    Button, Robert M.; Baez, Anastacio N.

    1994-01-01

    In the new climate of smaller, faster, and cheaper space science satellites, a new power system topology has been developed at the NASA Lewis Research Center. This new topology is based on a series connected boost converter (SCBC) and can greatly affect the size, weight, fault tolerance, and cost of any small spacecraft using photovoltaic solar arrays. The paper presents electric power system design factors and requirements as background information. The series connected boost converter topology is discussed and several advantages over existing technologies are illustrated. Besides being small, lightweight, and efficient, this topology has the added benefit of inherent fault tolerance. A positive ground power system test bed has been developed for the TROPIX spacecraft program. Performance of the SCBC in the test bed is described in detail. SCBC efficiencies of 95 percent to 98 percent have been measured. Finally, a modular, photovoltaic regulator 'kit' concept is presented. Two SCBC's are used to regulate solar array charging of batteries and to provide 'utilitytype' power to the user loads. The kit's modularity will allow a spacecraft electric power system to be built from off-the-shelf hardware; resulting in smaller, faster, and cheaper spacecraft.

  17. The numerical simulation of liquid sloshing on board spacecraft

    NARCIS (Netherlands)

    Veldman, A.E.P.; Gerrits, J.; Luppes, R.; Helder, J.A.; Vreeburg, J.P.B.

    2007-01-01

    The subject of study is the influence of sloshing liquid on the dynamics of spacecraft. A combined theoretical and experimental approach has been followed. On the one hand, CFD simulations have been carried out to predict the combined liquid/solid body motion. Basically a volume-of-fluid (VOF) appro

  18. Dynamic performance of an aero-assist spacecraft - AFE

    Science.gov (United States)

    Chang, Ho-Pen; French, Raymond A.

    1992-01-01

    Dynamic performance of the Aero-assist Flight Experiment (AFE) spacecraft was investigated using a high-fidelity 6-DOF simulation model. Baseline guidance logic, control logic, and a strapdown navigation system to be used on the AFE spacecraft are also modeled in the 6-DOF simulation. During the AFE mission, uncertainties in the environment and the spacecraft are described by an error space which includes both correlated and uncorrelated error sources. The principal error sources modeled in this study include navigation errors, initial state vector errors, atmospheric variations, aerodynamic uncertainties, center-of-gravity off-sets, and weight uncertainties. The impact of the perturbations on the spacecraft performance is investigated using Monte Carlo repetitive statistical techniques. During the Solid Rocket Motor (SRM) deorbit phase, a target flight path angle of -4.76 deg at entry interface (EI) offers very high probability of avoiding SRM casing skip-out from the atmosphere. Generally speaking, the baseline designs of the guidance, navigation, and control systems satisfy most of the science and mission requirements.

  19. 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...

  20. Projection-Based Reduced Order Modeling for Spacecraft Thermal Analysis

    Science.gov (United States)

    Qian, Jing; Wang, Yi; Song, Hongjun; Pant, Kapil; Peabody, Hume; Ku, Jentung; Butler, Charles D.

    2015-01-01

    This paper presents a mathematically rigorous, subspace projection-based reduced order modeling (ROM) methodology and an integrated framework to automatically generate reduced order models for spacecraft thermal analysis. Two key steps in the reduced order modeling procedure are described: (1) the acquisition of a full-scale spacecraft model in the ordinary differential equation (ODE) and differential algebraic equation (DAE) form to resolve its dynamic thermal behavior; and (2) the ROM to markedly reduce the dimension of the full-scale model. Specifically, proper orthogonal decomposition (POD) in conjunction with discrete empirical interpolation method (DEIM) and trajectory piece-wise linear (TPWL) methods are developed to address the strong nonlinear thermal effects due to coupled conductive and radiative heat transfer in the spacecraft environment. Case studies using NASA-relevant satellite models are undertaken to verify the capability and to assess the computational performance of the ROM technique in terms of speed-up and error relative to the full-scale model. ROM exhibits excellent agreement in spatiotemporal thermal profiles (analysis. These findings establish the feasibility of ROM to perform rational and computationally affordable thermal analysis, develop reliable thermal control strategies for spacecraft, and greatly reduce the development cycle times and costs.

  1. Spacecraft power system controller based on neural network

    Science.gov (United States)

    El-madany, Hanaa T.; Fahmy, Faten H.; El-Rahman, Ninet M. A.; Dorrah, Hassen T.

    2011-09-01

    Neural control is a branch of the general field of intelligent control, which is based on the concept of artificial intelligence. This work presents the spacecraft orbit determination, dimensioning of the renewable power system, and mathematical modeling of spacecraft power system which are required for simulating the system. The complete system is simulated using MATLAB-SIMULINK. The NN controller outperform PID in the extreme range of non-linearity. Well trained neural controller can operate at different conditions of load current at different orbital periods without any tuning such in case of PID controller. So an artificial neural network (ANN) based model has been developed for the optimum operation of spacecraft power system. An ANN is trained using a back propagation with Levenberg-Marquardt algorithm. The best validation performance is obtained for mean square error is equal to 9.9962×10 -11 at epoch 637. The regression between the network output and the corresponding target is equal to 100% which means a high accuracy. NNC architecture gives satisfactory results with small number of neurons, hence better in terms of memory and time are required for NNC implementation. The results indicate that the proposed control unit using ANN can be successfully used for controlling the spacecraft power system in low earth orbit (LEO). Therefore, this technique is going to be a very useful tool for the interested designers in space field.

  2. A novel single thruster control strategy for spacecraft attitude stabilization

    Science.gov (United States)

    Godard; Kumar, Krishna Dev; Zou, An-Min

    2013-05-01

    Feasibility of achieving three axis attitude stabilization using a single thruster is explored in this paper. Torques are generated using a thruster orientation mechanism with which the thrust vector can be tilted on a two axis gimbal. A robust nonlinear control scheme is developed based on the nonlinear kinematic and dynamic equations of motion of a rigid body spacecraft in the presence of gravity gradient torque and external disturbances. The spacecraft, controlled using the proposed concept, constitutes an underactuated system (a system with fewer independent control inputs than degrees of freedom) with nonlinear dynamics. Moreover, using thruster gimbal angles as control inputs make the system non-affine (control terms appear nonlinearly in the state equation). This necessitates the control algorithms to be developed based on nonlinear control theory since linear control methods are not directly applicable. The stability conditions for the spacecraft attitude motion for robustness against uncertainties and disturbances are derived to establish the regions of asymptotic 3-axis attitude stabilization. Several numerical simulations are presented to demonstrate the efficacy of the proposed controller and validate the theoretical results. The control algorithm is shown to compensate for time-varying external disturbances including solar radiation pressure, aerodynamic forces, and magnetic disturbances; and uncertainties in the spacecraft inertia parameters. The numerical results also establish the robustness of the proposed control scheme to negate disturbances caused by orbit eccentricity.

  3. Theory Of Controlling Spacecraft Motion With Pulsed Thrusters

    Science.gov (United States)

    Thurman, Sam W.; Flashner, Henryk

    1996-01-01

    Report presents new class of flight-control laws for making spacecraft follow desired trajectory by use of pulsed thrusters during such maneuvers as automated rendezvous on orbit and soft landing on planet. Although emphasis in report on guidance, ultimately shown same techniques also useful for attitude control and station keeping.

  4. Field Of View Of A Spacecraft Antenna: Analysis And Software

    Science.gov (United States)

    Wu, Te-Kao; Kipp, R.; Lee, S. W.

    1995-01-01

    Report summarizes computational analysis of field of view of rotating elliptical-cross-section parabolic-reflector antenna for SeaWinds spacecraft. Issues considered include blockage and diffraction by other objects near antenna, related concerns about electromagnetic interference and electromagnetic compatibility, and how far and in which configuration other objects positioned with respect to antenna to achieve required performance.

  5. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    Science.gov (United States)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  6. 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.

  7. Best Practices for Reliable and Robust Spacecraft Structures

    Science.gov (United States)

    Raju, Ivatury S.; Murthy, P. L. N.; Patel, Naresh R.; Bonacuse, Peter J.; Elliott, Kenny B.; Gordon, S. A.; Gyekenyesi, J. P.; Daso, E. O.; Aggarwal, P.; Tillman, R. F.

    2007-01-01

    A study was undertaken to capture the best practices for the development of reliable and robust spacecraft structures for NASA s next generation cargo and crewed launch vehicles. In this study, the NASA heritage programs such as Mercury, Gemini, Apollo, and the Space Shuttle program were examined. A series of lessons learned during the NASA and DoD heritage programs are captured. The processes that "make the right structural system" are examined along with the processes to "make the structural system right". The impact of technology advancements in materials and analysis and testing methods on reliability and robustness of spacecraft structures is studied. The best practices and lessons learned are extracted from these studies. Since the first human space flight, the best practices for reliable and robust spacecraft structures appear to be well established, understood, and articulated by each generation of designers and engineers. However, these best practices apparently have not always been followed. When the best practices are ignored or short cuts are taken, risks accumulate, and reliability suffers. Thus program managers need to be vigilant of circumstances and situations that tend to violate best practices. Adherence to the best practices may help develop spacecraft systems with high reliability and robustness against certain anomalies and unforeseen events.

  8. Assembly auxiliary system for narrow cabins of spacecraft

    Science.gov (United States)

    Liu, Yi; Li, Shiqi; Wang, Junfeng

    2015-09-01

    Due to the narrow space and complex structure of spacecraft cabin, the existing asssembly systems can not well suit for the assembly process of cabin products. This paper aims to introduce an assembly auxiliary system for cabin products. A hierarchical-classification method is proposed to re-adjust the initial assembly relationship of cabin into a new hierarchical structure for efficient assembly planning. An improved ant colony algorithm based on three assembly principles is established for searching a optimizational assembly sequence of cabin parts. A mixed reality assembly environment is constructed with enhanced information to promote interaction efficiency of assembly training and guidance. Based on the machine vision technology, the inspection of left redundant objects and measurement of parts distance in inner cabin are efficiently performed. The proposed system has been applied to the assembly work of a spacecraft cabin with 107 parts, which includes cabin assembly planning, assembly training and assembly quality inspection. The application result indicates that the proposed system can be an effective assistant tool to cabin assembly works and provide an intuitive and real assembly experience for workers. This paper presents an assembly auxiliary system for spacecraft cabin products, which can provide technical support to the spacecraft cabin assembly industry.

  9. A novel approach to modeling spacecraft spectral reflectance

    Science.gov (United States)

    Willison, Alexander; Bédard, Donald

    2016-10-01

    Simulated spectrometric observations of unresolved resident space objects are required for the interpretation of quantities measured by optical telescopes. This allows for their characterization as part of regular space surveillance activity. A peer-reviewed spacecraft reflectance model is necessary to help improve the understanding of characterization measurements. With this objective in mind, a novel approach to model spacecraft spectral reflectance as an overall spectral bidirectional reflectance distribution function (sBRDF) is presented. A spacecraft's overall sBRDF is determined using its triangular-faceted computer-aided design (CAD) model and the empirical sBRDF of its homogeneous materials. The CAD model is used to determine the proportional contribution of each homogeneous material to the overall reflectance. Each empirical sBRDF is contained in look-up tables developed from measurements made over a range of illumination and reflection geometries using simple interpolation and extrapolation techniques. A demonstration of the spacecraft reflectance model is provided through simulation of an optical ground truth characterization using the Canadian Advanced Nanospace eXperiment-1 Engineering Model nanosatellite as the subject. Validation of the reflectance model is achieved through a qualitative comparison of simulated and measured quantities.

  10. A CFD Approach to Modeling Spacecraft Fuel Slosh

    Science.gov (United States)

    Marsell, Brandon; Gangadharan, Sathya; Chatman, Yadira; Sudermann, James; Schlee, Keith; Ristow, James E.

    2009-01-01

    Energy dissipation and resonant coupling from sloshing fuel in spacecraft fuel tanks is a problem that occurs in the design of many spacecraft. In the case of a spin stabilized spacecraft, this energy dissipation can cause a growth in the spacecrafts' nutation (wobble) that may lead to disastrous consequences for the mission. Even in non-spinning spacecraft, coupling between the spacecraft or upper stage flight control system and an unanticipated slosh resonance can result in catastrophe. By using a Computational Fluid Dynamics (CFD) solver such as Fluent, a model for this fuel slosh can be created. The accuracy of the model must be tested by comparing its results to an experimental test case. Such a model will allow for the variation of many different parameters such as fluid viscosity and gravitational field, yielding a deeper understanding of spacecraft slosh dynamics. In order to gain a better understanding of the dynamics behind sloshing fluids, the Launch Services Program (LSP) at the NASA Kennedy Space Center (KSC) is interested in finding ways to better model this behavior. Thanks to past research, a state-of-the-art fuel slosh research facility was designed and fabricated at Embry Riddle Aeronautical University (ERAU). This test facility has produced interesting results and a fairly reliable parameter estimation process to predict the necessary values that accurately characterize a mechanical pendulum analog model. The current study at ERAU uses a different approach to model the free surface sloshing of liquid in a spherical tank using Computational Fluid Dynamics (CFD) methods. Using a software package called Fluent, a model was created to simulate the sloshing motion of the propellant. This finite volume program uses a technique called the Volume of Fluid (VOF) method to model the interaction between two fluids [4]. For the case of free surface slosh, the two fluids are the propellant and air. As the fuel sloshes around in the tank, it naturally

  11. Improving spacecraft design using a multidisciplinary design optimization methodology

    Science.gov (United States)

    Mosher, Todd Jon

    2000-10-01

    Spacecraft design has gone from maximizing performance under technology constraints to minimizing cost under performance constraints. This is characteristic of the "faster, better, cheaper" movement that has emerged within NASA. Currently spacecraft are "optimized" manually through a tool-assisted evaluation of a limited set of design alternatives. With this approach there is no guarantee that a systems-level focus will be taken and "feasibility" rather than "optimality" is commonly all that is achieved. To improve spacecraft design in the "faster, better, cheaper" era, a new approach using multidisciplinary design optimization (MDO) is proposed. Using MDO methods brings structure to conceptual spacecraft design by casting a spacecraft design problem into an optimization framework. Then, through the construction of a model that captures design and cost, this approach facilitates a quicker and more straightforward option synthesis. The final step is to automatically search the design space. As computer processor speed continues to increase, enumeration of all combinations, while not elegant, is one method that is straightforward to perform. As an alternative to enumeration, genetic algorithms are used and find solutions by reviewing fewer possible solutions with some limitations. Both methods increase the likelihood of finding an optimal design, or at least the most promising area of the design space. This spacecraft design methodology using MDO is demonstrated on three examples. A retrospective test for validation is performed using the Near Earth Asteroid Rendezvous (NEAR) spacecraft design. For the second example, the premise that aerobraking was needed to minimize mission cost and was mission enabling for the Mars Global Surveyor (MGS) mission is challenged. While one might expect no feasible design space for an MGS without aerobraking mission, a counterintuitive result is discovered. Several design options that don't use aerobraking are feasible and cost

  12. Bioinformatics methods for identifying candidate disease genes

    NARCIS (Netherlands)

    Driel, M.A. van; Brunner, H.G.

    2006-01-01

    With the explosion in genomic and functional genomics information, methods for disease gene identification are rapidly evolving. Databases are now essential to the process of selecting candidate disease genes. Combining positional information with disease characteristics and functional information i

  13. Cattle Candidate Genes for Milk Production Traits

    OpenAIRE

    Kadlec, Tomáš

    2012-01-01

    The aim of this thesis is to make an overview of important candidate genes affecting milk yield and milk quality parameters, with an emphasis on genes associated with the quantity and quality of milk proteins and milk fat.

  14. Evaluating historical candidate genes for schizophrenia

    DEFF Research Database (Denmark)

    Farrell, M S; Werge, T; Sklar, P;

    2015-01-01

    Prior to the genome-wide association era, candidate gene studies were a major approach in schizophrenia genetics. In this invited review, we consider the current status of 25 historical candidate genes for schizophrenia (for example, COMT, DISC1, DTNBP1 and NRG1). The initial study for 24...... of these genes explicitly evaluated common variant hypotheses about schizophrenia. Our evaluation included a meta-analysis of the candidate gene literature, incorporation of the results of the largest genomic study yet published for schizophrenia, ratings from informed researchers who have published...... on these genes, and ratings from 24 schizophrenia geneticists. On the basis of current empirical evidence and mostly consensual assessments of informed opinion, it appears that the historical candidate gene literature did not yield clear insights into the genetic basis of schizophrenia. A likely reason why...

  15. Towards Treating Chemistry Teacher Candidates as Human

    Science.gov (United States)

    Lewthwaite, Brian Ellis

    2008-05-01

    This research inquiry investigates the factors influencing chemistry teacher candidates’ development during their extended practica in the second and final year of an After-Degree Bachelor of Education at a university in central Canada. A variety of data sources are used to identify the risk and protective factors impeding and contributing to the achievement of their chemistry pedagogical aspirations. Two theoretical frameworks, both having their origins in the pioneering work of Kurt Lewin, are used to conceptualize how a complex amalgam of personal attribute and environmental factors and the interplay among these factors influence teacher candidate developmental trajectories. The tenets of both Bronfenbrenner’s bioecological model and Learning Environment research provide insights into how the factors influencing teacher candidate development can be understood and systematically documented to provide a template for reflective consideration of the practicum experience for both teacher candidates and those involved in fostering the development of chemistry teacher candidates.

  16. A genetic inventory of spacecraft and associated surfaces.

    Science.gov (United States)

    La Duc, Myron T; Venkateswaran, Kasthuri; Conley, Catharine A

    2014-01-01

    Terrestrial organisms or other contaminants that are transported to Mars could interfere with efforts to study the potential for indigenous martian life. Similarly, contaminants that make the round-trip to Mars and back to Earth could compromise the ability to discriminate an authentic martian biosignature from a terrestrial organism. For this reason, it is important to develop a comprehensive inventory of microbes that are present on spacecraft to avoid interpreting their traces as authentic extraterrestrial biosignatures. Culture-based methods are currently used by NASA to assess spacecraft cleanliness but deliberately detect only a very small subset of total organisms present. The National Research Council has recommended that molecular (DNA)-based identification techniques should be developed as one aspect of managing the risk that terrestrial contamination could interfere with detection of life on (or returned from) Mars. The current understanding of the microbial diversity associated with spacecraft and clean room surfaces is expanding, but the capability to generate a comprehensive inventory of the microbial populations present on spacecraft outbound from Earth would address multiple considerations in planetary protection, relevant to both robotic and human missions. To this end, a 6-year genetic inventory study was undertaken by a NASA/JPL team. It was completed in 2012 and included delivery of a publicly available comprehensive final report. The genetic inventory study team evaluated the utility of three analytical technologies (conventional cloning techniques, PhyloChip DNA microarrays, and 454 tag-pyrosequencing) and combined them with a systematic methodology to collect, process, and archive nucleic acids as the first steps in assessing the phylogenetic breadth of microorganisms on spacecraft and associated surfaces. PMID:24432775

  17. Do People 'Like' Candidates on Facebook?

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Kleis

    The online popularity of a few exceptional candidates has led many to suggest that social media have given politicians powerful ways of communicating directly with voters. In this paper, we examine whether this is happening on a significant scale and show, based on analysis of 224 candidates....... We therefore suggest that the political implications of social media are generally better understood in terms of facilitating indirect communication and institutional change than in terms of direct communication....

  18. Candidal Leukoplakia on Patient with Removable Denture

    OpenAIRE

    Shiril Paskalis; Anandina Irmagita

    2013-01-01

    Candida infection is a common problem in patients using removable dentures, with the most frequent type is denture stomatitis. But other type of candidal infection could also happen in these patients, such as candidal leukoplakia. We reported a 61 years old female patient who complained a painful lesion under her lower removable denture. Oral examination revealed white plaque that could not be rubbed over an ulcer on the lingual part of alveolar processes under the lower removable denture pla...

  19. Pulmonary Rehabilitation in Lung Transplant Candidates: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Stefanie Tonguino Rosero

    2013-09-01

    Full Text Available Pulmonary rehabilitation (PR aims to improve physical fitness and to decrease symptoms in patients with chronic lung disease; however there is not clear evidence regarding the benefits of PR in candidates for lung transplantation (LT. Objective. To determine the effectiveness of PR in LT candidates and also to find out how quality of life and exercise tolerance affects the survival of these patients. Methodology. Electronic databases (Medline, Cochrane, PEDro, Scient Direct and SciELO Search of articles in spanish, english or portuguese; controlled clinical trials and cohort studies published between 2000-2011 regarding PR in candidates for LT, the model of Cochrane systematic reviews was used. Results. The papers included were four cohort, two of which regarded of survival pre LT using the six minutes walking test (6MWT; a study of quality of life related to post LT survival and an exercise tolerance study. Controlled clinical trial was not found. Conclusions. The information found in the included studies had clinical and methodological heterogeneity therefore a meta-analysis could not been undertaken. The PR should be considered as an essential part to maintain the exercise tolerance and the patient’s survival. Research regarding this subject is important and should be carried out.

  20. Cardiac evaluation of liver transplant candidates

    Institute of Scientific and Technical Information of China (English)

    Mercedes Susan Mandell; JoAnn Lindenfeld; Mei-Yung Tsou; Michael Zimmerman

    2008-01-01

    Physicians previously thought that heart disease was rare in patients with end stage liver disease. However, recent evidence shows that the prevalence of ischemic heart disease and cardiomyopathy is increased in transplant candidates compared to most other surgical candidates. Investigators estimate that up to 26% of all liver transplant candidates have at least one critical coronary artery stenosis and that at least half of these patients will die perioperatively of cardiac complications. Cardiomyopathy also occurs in greater frequency. While all patients with advanced cardiac disease have defects in cardiac performance, a larger than expected number of patients have classical findings of dilated, restrictive and hypertropic cardiomyopathy. This may explain why up to 56% of patients suffer from hypoxemia due to pulmonary edema following transplant surgery. There is considerable controversy on how to screen transplant candidates for the presence of heart disease. Questions focus upon, which patients should be screened and what tests should be used. This review examines screening strategies for transplant candidates and details the prognostic value of common tests used to identify ischemic heart disease. We also review the physiological consequences of cardiomyopathy in transplant candidates and explore the specific syndrome of "cirrhotic cardiomyopathy".

  1. The source regions of solar energetic particles detected by widely separated spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jinhye; Moon, Y.-J. [School of Space Research, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Innes, D. E.; Bucik, R., E-mail: jinhye@khu.ac.kr [Max Planck Institute for Solar System Research, D-37191 Katlenburg-Lindau (Germany)

    2013-12-20

    We studied the source regions of 12 solar energetic particle (SEP) events seen between 2010 August and 2012 January at STEREO-A, B, and/or Earth (Advanced Composition Explorer/Solar and Heliospheric Observatory/GOES), when the two STEREO spacecraft were separated by about 180°. All events were associated with flares (C1 to X6) and fast coronal mass ejections and, except for one, accompanied by type II radio bursts. We have determined the arrival times of the SEPs at the three positions. Extreme ultraviolet (EUV) waves, observed in the 195 Å and 193 Å channels of STEREO and the Solar Dynamics Observatory, are tracked across the Sun to determine their arrival time at the photospheric source of open field lines connecting to the spacecraft. There is a good correlation between the EUV wave arrival times at the connecting footpoints and the SEP onset times. The delay time between electron onset and the EUV wave reaching the connecting footpoint is independent of distance from the flare site. The proton delay time increases with distance from the flare site. In three of the events, secondary flare sites may have also contributed to the wide longitudinal spread of SEPs.

  2. Suprathermal electrons at Saturn's bow shock

    CERN Document Server

    Masters, A; Sergis, N; Stawarz, L; Fujimoto, M; Coates, A J; Dougherty, M K

    2016-01-01

    The leading explanation for the origin of galactic cosmic rays is particle acceleration at the shocks surrounding young supernova remnants (SNRs), although crucial aspects of the acceleration process are unclear. The similar collisionless plasma shocks frequently encountered by spacecraft in the solar wind are generally far weaker (lower Mach number) than these SNR shocks. However, the Cassini spacecraft has shown that the shock standing in the solar wind sunward of Saturn (Saturn's bow shock) can occasionally reach this high-Mach number astrophysical regime. In this regime Cassini has provided the first in situ evidence for electron acceleration under quasi-parallel upstream magnetic conditions. Here we present the full picture of suprathermal electrons at Saturn's bow shock revealed by Cassini. The downstream thermal electron distribution is resolved in all data taken by the low-energy electron detector (CAPS-ELS, 18 keV) measured a suprathermal electron signature at 31 of 508 crossings, where typically onl...

  3. Identification of new transitional disk candidates in Lupus with Herschel

    Science.gov (United States)

    Bustamante, I.; Merín, B.; Ribas, Á.; Bouy, H.; Prusti, T.; Pilbratt, G. L.; André, Ph.

    2015-06-01

    Context. New data from the Herschel Space Observatory are broadening our understanding of the physics and evolution of the outer regions of protoplanetary disks in star-forming regions. In particular they prove to be useful for identifying transitional disk candidates. Aims: The goals of this work are to complement the detections of disks and the identification of transitional disk candidates in the Lupus clouds with data from the Herschel Gould Belt Survey. Methods: We extracted photometry at 70, 100, 160, 250, 350, and 500 μm of all spectroscopically confirmed Class II members previously identified in the Lupus regions and analyzed their updated spectral energy distributions. Results: We have detected 34 young disks in Lupus in at least one Herschel band, from an initial sample of 123 known members in the observed fields. Using recently defined criteria, we have identified five transitional disk candidates in the region. Three of them are new to the literature. Their PACS-70 μm fluxes are systematically higher than those of normal T Tauri stars in the same associations, as already found in T Cha and in the transitional disks in the Chamaeleon molecular cloud. Conclusions: Herschel efficiently complements mid-infrared surveys for identifying transitional disk candidates and confirms that these objects seem to have substantially different outer disks than the T Tauri stars in the same molecular clouds. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Tables 5-7 and Figs. 3 and 4 are available in electronic form at http://www.aanda.org

  4. 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

  5. Event display of a H -> 4e candidate event

    CERN Multimedia

    ATLAS, Collaboration

    2012-01-01

    Event display of a H -> 4e candidate event with m(4l) = 124.5 (124.6) GeV without (with) Z mass constraint. The masses of the lepton pairs are 70.6 GeV and 44.7 GeV. The event was recorded by ATLAS on 18-May-2012, 20:28:11 CEST in run number 203602 as event number 82614360. The tracks and clusters of the two electron pairs are colored red and blue, respectively. The three displays on the right-hand side show the r-phi view of the event (top), a zoom into the vertex region, indicating that the 4 electrons originate from the same primary vertex (middle), and a Lego plot indicating the amount of transverse energy Et measured in the calorimeters (bottom).

  6. Numerical Simulations of Spacecraft-Regolith Interactions on Asteroids

    Science.gov (United States)

    Ballouz, Ronald; Richardson, Derek C.; Michel, Patrick; Schwartz, Stephen R.

    2014-11-01

    NASA's OSIRIS-REx mission will rendezvous in 2018 with the near-Earth asteroid (101955) Bennu and attempt to touch down and obtain a sample from its surface. The regolith surface's behavior in response to the spacecraft's intrusion is difficult to predict due to the asteroid's extremely low-gravity environment (on the order of 10 micro-g's.) We have been carrying out high-resolution (N > 100,000) numerical simulations of the intrusion of a realistic physical model of the sampling device into a bed of cm-size spherical particles to explore the relationship between the spacecraft's response and the dynamical behavior of the regolith. If the granular bed is too compliant, then the spacecraft may sink into the asteroid. If the granular bed is not compliant enough, then the spacecraft may not be able to obtain an appropriate sample. This is further complicated by the fact that the degree of compliance is also dependent on the material properties of the regolith surface (size distribution, local slope, friction coefficients, shape effects). The ultimate goal of this study is to construct a library of touchdown outcomes as a function of the potential observables (local slope, estimated maximum angle of repose, and to a limited exited particle size distribution). We study the effect of varying the regolith's material properties (cohesive, frictional, and dissipative parameters) in order to place limits on the range of possible outcomes. The library will be useful for sample-site selection based on available observables, and, upon sampling, may aid in interpreting the physical properties of the regolith (e.g., depth and density) by comparing measurements from on-board instruments with simulation data. Preliminary results show that grains with low coefficients of friction (smooth particles) provide little resistance and the spacecraft sinks into the asteroid. For high coefficients of friction (effectively mimicking grain angularity), the regolith is much less compliant, and

  7. Electron isolation at ATLAS

    International Nuclear Information System (INIS)

    The ATLAS experiment at the Large Hadron Collider (LHC) will face the challenge of efficiently selecting interesting candidate events in pp collisions at 14 TeV centre-of-mass energy, whilst rejecting the enormous number of background events. Many of these interesting candidate events have isolated leptons in the final state, like for example events with a gauge boson or SUSY. On top of the standard ATLAS electron identification an isolation criterion has been developed using a likelihood as multivariate approach with several discriminating variables. The likelihood is constructed by selecting electrons from Z decays for the signal and for the background electrons from b quark jets. Results for the example of the associated Higgs boson production with top quarks and subsequent decay into a pair of W bosons are presented. In addition first results of a likelihood to discriminate against jets are given and a possible extension for muons is discussed

  8. Applicability of Aerospace Materials Ground Flammability Test Data to Spacecraft Environments Theory and Applied Technologies

    Science.gov (United States)

    Hirsch, David; Williams, Jim; Beeson, Harold

    2009-01-01

    This slide presentation reviews the use of ground test data in reference to flammability to spacecraft environments. It reviews the current approach to spacecraft fire safety, the challenges to fire safety that the Constellation program poses, the current trends in the evaluation of the Constellation materials flammability, and the correlation of test data from ground flammability tests with the spacecraft environment. Included is a proposal for testing and the design of experiments to test the flammability of materials under similar spacecraft conditions.

  9. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  10. 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...

  11. Computational Fluid Dynamics Uncertainty Analysis for Payload Fairing Spacecraft Environmental Control Systems

    Science.gov (United States)

    Groves, Curtis; Ilie, Marcel; Schallhorn, Paul

    2014-01-01

    Spacecraft components may be damaged due to airflow produced by Environmental Control Systems (ECS). There are uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field around a spacecraft from the ECS System. This paper describes an approach to estimate the uncertainty in using CFD to predict the airflow speeds around an encapsulated spacecraft.

  12. Charging rates of metal-dielectric structures. [with implications for spacecraft

    Science.gov (United States)

    Purvis, C. K.; Staskus, J. V.; Roche, J. C.; Berkopec, F. D.

    1979-01-01

    Metal plates partially covered by 0.01-centimeter-thick fluorinated ethylene-propylene (FEP) Teflon were charged in the Lewis Research Center's geomagnetic substorm simulation facility using 5-, 8-, 10-, and 12-kilovolt electron beams. Surface voltage as a function of time was measured for various initial conditions (Teflon discharged or precharged) with the metal plate grounded or floating. Results indicate that both the charging rates and the levels to which the samples become charged are influenced by the geometry and initial charge state of the insulating surfaces. The experiments are described and the results are presented and discussed. NASA charging analyzer program (NASCAP) models of the experiments have been generated, and the predictions obtained are described. Implications of the study results for spacecraft are discussed.

  13. The substructure of a flux transfer event observed by the MMS spacecraft

    Science.gov (United States)

    Hwang, K.-J.; Sibeck, D. G.; Giles, B. L.; Pollock, C. J.; Gershman, D.; Avanov, L.; Paterson, W. R.; Dorelli, J. C.; Ergun, R. E.; Russell, C. T.; Strangeway, R. J.; Mauk, B.; Cohen, I. J.; Torbert, R. B.; Burch, J. L.

    2016-09-01

    On 15 August 2015, MMS (Magnetospheric Multiscale mission), skimming the dusk magnetopause, detected an isolated region of an increased magnetic strength and bipolar Bn, indicating a flux transfer event (FTE). The four spacecraft in a tetrahedron allowed for investigations of the shape and motion of the FTE. In particular, high-resolution particle data facilitated our exploration of FTE substructures and their magnetic connectivity inside and surrounding the FTE. Combined field and plasma observations suggest that the core fields are open, magnetically connected to the northern magnetosphere from which high-energy particles leak; ion "D" distributions characterize the axis of flux ropes that carry old-opened field lines; counterstreaming electrons superposed by parallel-heated components populate the periphery surrounding the FTE; and the interface between the core and draped regions contains a separatrix of newly opened magnetic field lines that emanate from the X line above the FTE.

  14. Development status of solid polymer electrolyte water electrolysis for manned spacecraft life support systems

    Science.gov (United States)

    Nuttall, L. J.; Titterington, W. A.

    1974-01-01

    Details of the design and system verification test results are presented for a six-man-rated oxygen generation system. The system configuration incorporates components and instrumentation for computer-controlled operation with automatic start-up/shutdown sequencing, fault detection and isolation, and with self-contained sensors and controls for automatic safe emergency shutdown. All fluid and electrical components, sensors, and electronic controls are designed to be easily maintainable under zero-gravity conditions. On-board component spares are utilized in the system concept to sustain long-term operation (six months minimum) in a manned spacecraft application. The system is centered on a 27-cell solid polymer electrolyte water electrolysis module which, combined with the associated system components and controls, forms a total system envelope 40 in. high, 40 in. wide, and 30 in. deep.

  15. Detection of surface glow related to spacecraft glow phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Langer, W.D.; Cohen, S.A.; Manos, D.M.; Motley, R.W.; Ono, M.; Paul, S.; Roberts, D.; Selberg, H.

    1986-02-01

    We have developed a high flux source of low energy neutral beams to study the spacecraft glow phenomena by using a biased limiter to neutralize plasma in ACT-1. Beams of nitrogen and nitrogen-oxygen mixtures with energies of 1 to 15 eV and fluxes greater than or equal to 10/sup 14//cm/sup 2//s were directed on target surfaces consisting of Z-302 and Z-306 paints. With the nitrogen beams we successfully detected a glow due to beam-surface interactions. In addition, we discovered a volume glow effect due to beam-gas interactions which may also play a role in spacecraft glow. 11 refs., 14 figs.

  16. Navigation between the planets. [Viking spacecraft flight to Mars

    Science.gov (United States)

    Melbourne, W. G.

    1976-01-01

    Recent advances in spacecraft tracking, chronometry, ephemerides, and orbit and trajectory determinations are reviewed. Improvements in timekeeping are reviewed, as well as precision distance and range measurements; orbit determinations, trajectory-correction maneuvers, flight path optimization, and information provided by rotation of the tracking station with the earth's surface. Doppler and tropospheric wave propagation effects are dealt with. Nongravitational perturbations (solar radiation pressure, release of gases from the spacecraft, stochastic unmodeled accelerations and sequential estimation to cope with them), the effect of the target planet's gravitational field upon close approach, and navigation problems in the outer reaches of the solar system (TV data telemetered back for inertial navigation) are covered. By-products of the research include: refined data on the mass of planets, on planetary mass distributions, planet configurations, on physical properties of the atmospheres and ionospheres of planets, and opportunities for refined tests of gravitation and relativity theories and models.

  17. A study of Schwarz converters for nuclear powered spacecraft

    Science.gov (United States)

    Stuart, Thomas A.; Schwarze, Gene E.

    1987-01-01

    High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation; parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.

  18. A computational algorithm for spacecraft control and momentum management

    Science.gov (United States)

    Dzielski, John; Bergmann, Edward; Paradiso, Joseph

    1990-01-01

    Developments in the area of nonlinear control theory have shown how coordinate changes in the state and input spaces of a dynamical system can be used to transform certain nonlinear differential equations into equivalent linear equations. These techniques are applied to the control of a spacecraft equipped with momentum exchange devices. An optimal control problem is formulated that incorporates a nonlinear spacecraft model. An algorithm is developed for solving the optimization problem using feedback linearization to transform to an equivalent problem involving a linear dynamical constraint and a functional approximation technique to solve for the linear dynamics in terms of the control. The original problem is transformed into an unconstrained nonlinear quadratic program that yields an approximate solution to the original problem. Two examples are presented to illustrate the results.

  19. A distributed microprocessor system for spacecraft control and data handling

    Science.gov (United States)

    Rennels, D. A.

    1977-01-01

    The specific requirements for spacecraft computing systems are considered. These requirements are partly related to the constraints of limited resources of power, weight, and volume. Another important factor is the requirement of extremely high reliability. These reliability requirements have led to introduction of automated redundancy techniques on board the spacecraft. The various redundant computers check each other and provide recovery procedures when a computer is found to have failed. Past and future capabilities are considered along with distributed processing requirements. System considerations are discussed, taking into account suboptimum computer throughput, sensitivity to software modifications, hierarchic timing, I/O granularity, restricted communications, synchronous functions, hierarchic control, and concurrent error detection. A description is presented of the Unified Data System (UDS), which consists of a set of standard microcomputers connected by several buses. Attention is also given to synchronization and timing, the executive control structure, the programming language, and the executive program.

  20. Studies on Precise Spacecraft Navigation and Positioning Using GPS

    Institute of Scientific and Technical Information of China (English)

    XiangKaiheng; QuGuangji

    2004-01-01

    GPS measurement technology, Encke method to solve satellite orbit perturbation and generalized Kalman filtering technology are organically combined together, and an innovative solution—carrier phase & pseudorange integrated dynamic orbit determination (CPPIDOD) for low earth orbit spacecraft on-board autonomous precise navigation and positioning by using GPS is presented. The difficult problems of dynamically resolving integer ambiguities and amendment of cycle slips in the application of GPS carrier phase have been solved.Based on all above, the technique of carrier phase & pseudorange integrated dynamic differential relative navigation between two spacecrafts is brought forward. Results of numerical simulation analyses and senti-physical simulation tests show that the solutions presented in this paper are feasible, which can significantly improve the performance of GPS positioning, and the models, algorithms and software are practical for engineering use.

  1. A Web Based Collaborative Design Environment for Spacecraft

    Science.gov (United States)

    Dunphy, Julia

    1998-01-01

    In this era of shrinking federal budgets in the USA we need to dramatically improve our efficiency in the spacecraft engineering design process. We have come up with a method which captures much of the experts' expertise in a dataflow design graph: Seamlessly connectable set of local and remote design tools; Seamlessly connectable web based design tools; and Web browser interface to the developing spacecraft design. We have recently completed our first web browser interface and demonstrated its utility in the design of an aeroshell using design tools located at web sites at three NASA facilities. Multiple design engineers and managers are now able to interrogate the design engine simultaneously and find out what the design looks like at any point in the design cycle, what its parameters are, and how it reacts to adverse space environments.

  2. Neural adaptive attitude tracking controller for flexible spacecraft

    Institute of Scientific and Technical Information of China (English)

    XIAO Bing; HU Qing-lei; MA Guang-fu

    2010-01-01

    In this paper,a neural network adaptive controller is proposed for attitude tracking of flexible spacecraft in presence of unknown inertial matrix and external disturbance.In this approach,neural network technique is employed to approximate the unknown system dynamics with finite combinations of some basis functions,and a robust controller is also designed to attenuate the effect of approximation error,more specially,the knowledge of angular velocity is not required.In the closed-loop system,Lyapunov stability analysis shows that the attitude trajectories asymptotically follow the reference output trajectories.Finally,simulation results are presented for the attitude tracking of a flexible spacecraft to show the excellent performance of the proposed controller and illustrate its robustness in face of external disturbances and unknown dynamics.

  3. 3D Reconfigurable MPSoC for Unmanned Spacecraft Navigation

    Science.gov (United States)

    Dekoulis, George

    2016-07-01

    This paper describes the design of a new lightweight spacecraft navigation system for unmanned space missions. The system addresses the demands for more efficient autonomous navigation in the near-Earth environment or deep space. The proposed instrumentation is directly suitable for unmanned systems operation and testing of new airborne prototypes for remote sensing applications. The system features a new sensor technology and significant improvements over existing solutions. Fluxgate type sensors have been traditionally used in unmanned defense systems such as target drones, guided missiles, rockets and satellites, however, the guidance sensors' configurations exhibit lower specifications than the presented solution. The current implementation is based on a recently developed material in a reengineered optimum sensor configuration for unprecedented low-power consumption. The new sensor's performance characteristics qualify it for spacecraft navigation applications. A major advantage of the system is the efficiency in redundancy reduction achieved in terms of both hardware and software requirements.

  4. Optimal Sliding Mode Controllers for Attitude Stabilization of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2011-01-01

    Full Text Available The robust optimal attitude control problem for a flexible spacecraft is considered. Two optimal sliding mode control laws that ensure the exponential convergence of the attitude control system are developed. Integral sliding mode control (ISMC is applied to combine the first-order sliding mode with optimal control and is used to control quaternion-based spacecraft attitude manoeuvres with external disturbances and an uncertainty inertia matrix. For the optimal control part the state-dependent Riccati equation (SDRE and optimal Lyapunov techniques are employed to solve the infinite-time nonlinear optimal control problem. The second method of Lyapunov is used to guarantee the stability of the attitude control system under the action of the proposed control laws. An example of multiaxial attitude manoeuvres is presented and simulation results are included to verify the usefulness of the developed controllers.

  5. Quaternion normalization in additive EKF for spacecraft attitude determination

    Science.gov (United States)

    Bar-Itzhack, I. Y.; Deutschmann, J.; Markley, F. L.

    1991-01-01

    This work introduces, examines, and compares several quaternion normalization algorithms, which are shown to be an effective stage in the application of the additive extended Kalman filter (EKF) to spacecraft attitude determination, which is based on vector measurements. Two new normalization schemes are introduced. They are compared with one another and with the known brute force normalization scheme, and their efficiency is examined. Simulated satellite data are used to demonstrate the performance of all three schemes. A fourth scheme is suggested for future research. Although the schemes were tested for spacecraft attitude determination, the conclusions are general and hold for attitude determination of any three dimensional body when based on vector measurements, and use an additive EKF for estimation, and the quaternion for specifying the attitude.

  6. Controllability of an underactuated spacecraft with one thruster under disturbance

    Institute of Scientific and Technical Information of China (English)

    Dong-Xia Wang; Ying-Hong Jia; Lei Jin; Hai-Chao Gui; Shi-Jie Xu

    2012-01-01

    For an underactuated spacecraft using only one thruster,the attitude controllability with respect to the orbit frame is studied in the presence of periodical oscillation disturbance,which provides a preconditional guide on designing control law for underactuated attitude control system.Firstly,attitude dynamic model was established for an underactuated spacecraft,and attitude motion was described using the special orthogonal group (SO (3)).Secondly,Liouville theorem was used to confirm that the flow generated by the drift vector of the underactuated attitude control system is volume-preserving.Furthermore,according to Poincaré's recurrence theorem,we draw conclusions that this drift field is weakly positively poisson stable (WPPS).Thirdly,the sufficient and necessary condition of controllability was obtained on the basis of lie algebra rank condition (LARC).Finally,the controllable conditions were analyzed and simulated in different cases of inertia matrix with the installed position of thruster.

  7. A formal method for early spacecraft design verification

    Science.gov (United States)

    Fischer, P. M.; Ludtke, D.; Schaus, V.; Gerndt, A.

    In the early design phase of a spacecraft, various aspects of the system under development are described and modeled using parameters such as masses, power consumption or data rates. In particular power and data parameters are special since their values can change depending on the spacecrafts operational mode. These mode-dependent parameters can be easily verified to static requirements like a maximumdata rate. Such quick verifications allow the engineers to check the design after every change they apply. In contrast, requirements concerning the mission lifetime such as the amount of downlinked data during the whole mission, demands a more complex procedure. We propose an executable model together with a simulation framework to evaluate complex mission scenarios. In conjunction with a formalized specification of mission requirements it allows a quick verification by means of formal methods.

  8. Spacecraft Testing Programs: Adding Value to the Systems Engineering Process

    Science.gov (United States)

    Britton, Keith J.; Schaible, Dawn M.

    2011-01-01

    Testing has long been recognized as a critical component of spacecraft development activities - yet many major systems failures may have been prevented with more rigorous testing programs. The question is why is more testing not being conducted? Given unlimited resources, more testing would likely be included in a spacecraft development program. Striking the right balance between too much testing and not enough has been a long-term challenge for many industries. The objective of this paper is to discuss some of the barriers, enablers, and best practices for developing and sustaining a strong test program and testing team. This paper will also explore the testing decision factors used by managers; the varying attitudes toward testing; methods to develop strong test engineers; and the influence of behavior, culture and processes on testing programs. KEY WORDS: Risk, Integration and Test, Validation, Verification, Test Program Development

  9. Searching sequences of resonant orbits between a spacecraft and Jupiter

    International Nuclear Information System (INIS)

    This research shows a study of the dynamical behavior of a spacecraft that performs a series of close approaches with the planet Jupiter. The main idea is to find a sequence of resonant orbits that allows the spacecraft to stay in the region of the space near the orbit of Jupiter around the Sun gaining energy from each passage by the planet. The dynamical model considers the existence of only two massive bodies in the systems, which are the Sun and Jupiter. They are assumed to be in circular orbits around their center of mass. Analytical equations are used to obtain the values of the parameters required to get this sequence of close approaches. Those equations are useful, because they show which orbits are physically possible when taking into account that the periapsis distances have to be above the surface of the Sun and that the closest approach distances during the passage by Jupiter have to be above its surface

  10. Optimal Variable-Structure Control Tracking of Spacecraft Maneuvers

    Science.gov (United States)

    Crassidis, John L.; Vadali, Srinivas R.; Markley, F. Landis

    1999-01-01

    An optimal control approach using variable-structure (sliding-mode) tracking for large angle spacecraft maneuvers is presented. The approach expands upon a previously derived regulation result using a quaternion parameterization for the kinematic equations of motion. This parameterization is used since it is free of singularities. The main contribution of this paper is the utilization of a simple term in the control law that produces a maneuver to the reference attitude trajectory in the shortest distance. Also, a multiplicative error quaternion between the desired and actual attitude is used to derive the control law. Sliding-mode switching surfaces are derived using an optimal-control analysis. Control laws are given using either external torque commands or reaction wheel commands. Global asymptotic stability is shown for both cases using a Lyapunov analysis. Simulation results are shown which use the new control strategy to stabilize the motion of the Microwave Anisotropy Probe spacecraft.

  11. Secure communications with low-orbit spacecraft using quantum cryptography

    Science.gov (United States)

    Hughes, Richard J.; Buttler, William T.; Kwiat, Paul G.; Luther, Gabriel G.; Morgan, George L; Nordholt, Jane E.; Peterson, Charles G.; Simmons, Charles M.

    1999-01-01

    Apparatus and method for secure communication between an earth station and spacecraft. A laser outputs single pulses that are split into preceding bright pulses and delayed attenuated pulses, and polarized. A Pockels cell changes the polarization of the polarized delayed attenuated pulses according to a string of random numbers, a first polarization representing a "1," and a second polarization representing a "0." At the receiving station, a beamsplitter randomly directs the preceding bright pulses and the polarized delayed attenuated pulses onto longer and shorter paths, both terminating in a beamsplitter which directs the preceding bright pulses and a first portion of the polarized delayed attenuated pulses to a first detector, and a second portion of the polarized delayed attenuated pulses to a second detector to generate a key for secure communication between the earth station and the spacecraft.

  12. Several key problems in automatic layout design of spacecraft modules

    Institute of Scientific and Technical Information of China (English)

    SUN Zhiguo; TENG Hongfei; LIU Zhanwei

    2003-01-01

    Computer-aided layout design of spacecraft modules, such as satellite modules and manned spaceship modules, is of great significance and egregious complexity. It is known as a combinatorial optimization and NPC problem in mathematics, a conceptual design and complex system in engineering. The main difficulties include representation and formulation of the problem in mathematics and the solution strategy and pragmatic approaches in engineering practice. After a brief survey of the state-of-the-art in relevant fields, this paper summarizes the research work of the authors' group on automatic layout design of spacecraft modules in the last 15 years, mainly focusing on 5 key problems. They are modeling and problem-solving algorithms, interference calculation, theory and applications of layout topological pattern, decision-making in layout design, and their pragmatic approaches in engineering practice.

  13. Kepler Stars with Multiple Transiting Planet Candidates

    Science.gov (United States)

    Lissauer, Jack J.

    2012-01-01

    NASA's Kepler spacecraft was launched into an Earth-trailing heliocentric orbit in March of 2009. Kepler is designed to conduct a statistical census of planetary system properties using transit photometry. Among the most exciting early results from Kepler are target stars found to have photometric signatures that suggest the presence of more than one transiting planet. Individual transiting planets provide information on the size and orbital period distributions of exoplanets. Multiple transiting planets provide additional information on the spacing and flatness distributions of planetary systems. Results to d ate and plans for future analysis will be presented.

  14. Acousto-Optical/Electronic Processor For SAR

    Science.gov (United States)

    Bicknell, T. J.; Farr, W. H.

    1992-01-01

    Lightweight, compact, low-power apparatus processes synthetic-aperture-radar (SAR) returns in real time, providing imagery aboard moving aircraft or spacecraft platform. Processor includes optical and electronic subsystems that, together, resolve range and azimuth coordinates of radar targets by combination of spatial and temporal integrations.

  15. Integrated precise orbit determination of Shenzhou Ⅳ unmanned spacecraft

    Institute of Scientific and Technical Information of China (English)

    Lü Congmin; GU Yidong; LIN Baojun; GUO Jiong

    2004-01-01

    Considering the characteristic orbit of Shenzhou Ⅳ spacecraft and the advantages and disadvantages of several types of domestic orbit measurements, a scheme of IPOD is determined, which uses GPS, SLR and USB observation data jointly plus precise ionosphere corrections to GPS observation data. IPOD system and mathematic models of OD are introduced. The results of different joint OD are analyzed using true observation data, and show that radial accuracy is better than 2 m.

  16. Communicating by Doppler: Detecting Spacecraft Dynamics During Critical Maneuvers

    Science.gov (United States)

    Asmar, Sami W.

    2012-01-01

    Communicating information from spacecraft in deep space utilizes sophisticated techniques of modulations onto a microwave signal carrier. Under most conditions, there is a high success rate of sending commands to the spacecraft and receiving science data acquired by on-board instruments along with health and status information. There are conditions, however, where the signal dynamics are too high and/or the received signal-to-noise ratio is below the receiver threshold. Under these conditions, often by design and sometimes as a result of planned or unplanned critical maneuvers, events (e.g., orbit insertion or descent and landing), safe mode, etc., it becomes highly critical but exceedingly challenging to receive information about the health and dynamical behavior of the spacecraft. The Deep Space Network, being a world-class instrument for Radio Science research, developed openloop receivers, called the Radio Science Receiver, designed to capture the raw incoming electromagnetic signals and associated noise for Radio Science experiments; post data capture digital signal processing extracts the signal carrier for scientific analysis. This receiver provides a high level of configuration flexibility and can be optimized for the various types of experiments. In addition to its scientific utility, it proved to be useful, and in some cases critical, for the support of missions during specific scenarios were the link budget is below the threshold of the tracking receiver to maintain lock or the frequency dynamics are faster than the limits of the tracking receiver. In these cases, the signal carrier is often detected only in the open-loop receiver to provide information on the specific behavior of the spacecraft from the carrier dynamics. This paper describes the utility of the system to support mission-critical events for the three cases of Cassini's Saturn orbit insertion, Huygens Titan landing, and Mars rovers landing.

  17. Spacecraft Trajectory Analysis and Mission Planning Simulation (STAMPS) Software

    Science.gov (United States)

    Puckett, Nancy; Pettinger, Kris; Hallstrom,John; Brownfield, Dana; Blinn, Eric; Williams, Frank; Wiuff, Kelli; McCarty, Steve; Ramirez, Daniel; Lamotte, Nicole; Vu, Tuan

    2014-01-01

    STAMPS simulates either three- or six-degree-of-freedom cases for all spacecraft flight phases using translated HAL flight software or generic GN&C models. Single or multiple trajectories can be simulated for use in optimization and dispersion analysis. It includes math models for the vehicle and environment, and currently features a "C" version of shuttle onboard flight software. The STAMPS software is used for mission planning and analysis within ascent/descent, rendezvous, proximity operations, and navigation flight design areas.

  18. Research on Robust Control of Nonlinear Fuzzy VSS for Spacecraft

    Institute of Scientific and Technical Information of China (English)

    DONG Shou-quan; BI Kai-bo

    2007-01-01

    The nonlinear dynamic system of spacecraft with uncertainty and coupling is analyzed and its general dynamical equation is given. The decoupling-ability and controllability are proved. Aiming at this system, a new nonlinear decoupling controlling method is put forward by synthetically using the variable structure and fuzzy theory. The simulation results show that this method is effective in tracking performances under the existence of uncertainty and outer disturbance.

  19. Angular rate estimation for multi-body spacecraft attitude control

    OpenAIRE

    Palermo, William J.

    2001-01-01

    Spacecraft with high performance attitude control systems requirements have traditionally relied on imperfect mechanical gyroscopes for primary attitude determination. Gyro bias errors are corrected with a Kalman filter algorithm that uses updates from precise attitude sensors like star trackers. Gyroscopes, however, have a tendency to degrade or fail on orbit, becoming a life limiting factor for many satellites. When errors become erratic, pointing accuracy may be lost during short star gaps...

  20. Differential Evolution Optimization for Targeting Spacecraft Maneuver Plans

    Science.gov (United States)

    Mattern, Daniel

    2016-01-01

    Previous analysis identified specific orbital parameters as being safer for conjunction avoidance for the TDRS fleet. With TDRS-9 being considered an at-risk spacecraft, a potential conjunction concern was raised should TDRS-9 fail while at a longitude of 12W. This document summarizes the analysis performed to identify if these specific orbital parameters could be targeted using the remaining drift-termination maneuvers for the relocation of TDRS-9 from 41W longitude to 12W longitude.