Science.gov

Sample records for earth orbit environment

  1. Neutron Environment Calculations for Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Clowdsley, M. S.; Wilson, J. W.; Shinn, J. L.; Badavi, F. F.; Heinbockel, J. H.; Atwell, W.

    2001-01-01

    The long term exposure of astronauts on the developing International Space Station (ISS) requires an accurate knowledge of the internal exposure environment for human risk assessment and other onboard processes. The natural environment is moderated by the solar wind, which varies over the solar cycle. The HZETRN high charge and energy transport code developed at NASA Langley Research Center can be used to evaluate the neutron environment on ISS. A time dependent model for the ambient environment in low earth orbit is used. This model includes GCR radiation moderated by the Earth's magnetic field, trapped protons, and a recently completed model of the albedo neutron environment formed through the interaction of galactic cosmic rays with the Earth's atmosphere. Using this code, the neutron environments for space shuttle missions were calculated and comparisons were made to measurements by the Johnson Space Center with onboard detectors. The models discussed herein are being developed to evaluate the natural and induced environment data for the Intelligence Synthesis Environment Project and eventual use in spacecraft optimization.

  2. Cosmic ray environment model for Earth orbit

    NASA Technical Reports Server (NTRS)

    Edmonds, L.

    1985-01-01

    A set of computer codes, which include the effects of the Earth's magnetic field, used to predict the cosmic ray environment (atomic numbers 1 through 28) for a spacecraft in a near-Earth orbit is described. A simple transport analysis is used to approximate the environment at the center of a spherical shield of arbitrary thickness. The final output is in a form (a Heinrich Curve) which has immediate applications for single event upset rate predictions. The codes will culate the time average environment for an arbitrary number (fractional or whole) of circular orbits. The computer codes were run for some selected orbits and the results, which can be useful for quick estimates of single event upset rates, are given. The codes were listed in the language HPL, which is appropriate or a Hewlett Packard 9825B desk top computer. Extensive documentation of the codes is available from COSMIC, except where explanations have been deferred to references where extensive documentation can be found. Some qualitative aspects of the effects of mass and magnetic shielding are also discussed.

  3. Energetic particle environment in near-Earth orbit.

    PubMed

    Klecker, B

    1996-01-01

    The hazard of exposure to high doses of ionizing radiation is one of the primary concerns of extended manned space missions and a continuous threat for the numerous spacecraft in operation today. In the near-Earth environment the main sources of radiation are solar energetic particles (SEP), galactic cosmic rays (GCR), and geomagnetically trapped particles, predominantly protons and electrons. The intensity of the SEP and GCR source depends primarily on the phase of the solar cycle. Due to the shielding effect of the Earth's magnetic field, the observed intensity of SEP and GCR particles in a near-Earth orbit will also depend on the orbital parameters altitude and inclination. The magnetospheric source strength depends also on these orbital parameters because they determine the frequency and location of radiation belt passes. In this paper an overview of the various sources of radiation in the near-Earth orbit will be given and first results obtained with the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) will be discussed. SAMPEX was launched on 3 July 1992 into a near polar (inclination 82 degrees) low altitude (510 x 675 km) orbit. The SAMPEX payload contains four separate instruments of high sensitivity covering the energy range 0.5 to several hundred MeV/nucleon for ions and 0.4 to 30 MeV for electrons. This low altitude polar orbit with zenith-oriented instrumentation provides a new opportunity for a systematic study of the near-Earth energetic particle environment. PMID:11540369

  4. Natural and Induced Environment in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Badavi, Francis F.; Kim, Myung-Hee Y.; Clowdsley, Martha S.; Heinbockel, John H.; Cucinotta, Francis A.; Badhwar, Gautam D.; Atwell, William; Huston, Stuart L.

    2002-01-01

    The long-term exposure of astronauts on the developing International Space Station (ISS) requires an accurate knowledge of the internal exposure environment for human risk assessment and other onboard processes. The natural environment is moderated by the solar wind which varies over the solar cycle. The neutron environment within the Shuttle in low Earth orbit has two sources. A time dependent model for the ambient environment is used to evaluate the natural and induced environment. The induced neutron environment is evaluated using measurements on STS-31 and STS-36 near the 1990 solar maximum.

  5. Historical Evolution of the Low Earth Orbit Debris Environment

    NASA Astrophysics Data System (ADS)

    Walker, R.; Wilkinson, J.; Stokes, H.; Swinerd, G.

    The importance of modelling the historical evolution of the orbital debris environment is discussed. The DERA IDES debris model is introduced and the elements of the model that are used to simulate historical environment evolution are briefly described. High resolution IDES model simulations of the historical debris environment evolution in Low Earth Orbit (LEO) are then presented for centimetre and decimetre object size thresholds. The simulated environment evolution dynamics are fully explained. Discrete increases in the LEO object density can be correlated to specific debris source events. Examples of the IDES model validation process are given, consisting of comparisons between the model simulation and debris measurement data. It was found that the model exhibited reasonable accuracy for the centimetre and decimetre object size thresholds, leading to improved confidence when performing long-term environment projections.

  6. Effects of the low Earth orbital environment on spacecraft materials

    NASA Technical Reports Server (NTRS)

    Leger, L. J.

    1986-01-01

    It is evident from space flights during the last three years that the low Earth orbital (LEO) environment interacts with spacecraft surfaces in significant ways. One manifestation of these interactions is recession of, in particular, organic-polymer-based surfaces presumably due to oxidation by atomic oxygen, the major component of the LEO environment. Three experiments have been conducted on Space Shuttle flights 5, 8 and 41-G to measure reaction rates and the effects of various parameters on reaction rates. Surface recession on these flights indicates reaction efficiencies approximately 3 x 10(-24) cu cm/atoms for unfilled organic polymers. Of the metals, silver and osmium are very reactive. Effects on spacecraft or experiment surfaces can be evaluated using the derived reaction efficiencies and a definition of the total exposure to atomic oxygen. This exposure is obtained using an ambient density model, solar activity data and spacecraft parameters of altitude, attitude and operational date. Oxygen flux on a given surface is obtained from the ambient density and spacecraft velocity and can then be integrated to provide the total exposure or fluence. Such information can be generated using simple computational programs and can be converted to various formats. Overall, the extent of damage is strongly dependent on the type of surface and total exposure time.

  7. Laboratory investigations: Low Earth orbit environment chemistry with spacecraft surfaces

    NASA Technical Reports Server (NTRS)

    Cross, Jon B.

    1990-01-01

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

  8. The low earth orbit environment observed using CREAM and CREDO.

    PubMed

    Watson, C J; Dyer, C S; Truscott, P R; Peerless, C L; Sims, A J; Barth, J L

    1998-01-01

    The Cosmic Radiation Environment and Dosimetry experiment (CREDO) has been operational on board the Advanced Photovoltaics & Electronics Experiment Spacecraft since August 1994. Extensive measurements of cosmic ray linear energy transfer spectra (using data to January 1996) and total dose (using data to November 1994) have been made, and compared with predictions of standard models. Detailed consideration of spacecraft shielding effects have been made. Predictions are shown to overestimate the measured linear energy transfer spectra. The CREAM experiment was flown on STS-63 in the SpaceHab module. Results show penetration of high energy electrons into the SpaceHab module. PMID:11542876

  9. The effect of the low Earth orbit environment on space solar cells

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Hickey, John R.; Brasted, Donald K.

    1990-01-01

    The results of a space flight experiment designed to provide reference cell standards for photovoltaic measurements as well as to investigate the solar spectrum and the effect of long-term exposure of solar cells to the space environment are presented. This experiment, the Advanced Photovoltaic Experiment (APEX), was launched into low Earth orbit as part of the Long Duration Exposure Facility in 1984 and retrieved 69 months later. APEX contained over 150 solar cells of a wide variety of materials, designs and coverglasses. Data on cell performance was recorded for the first year-on-orbit.

  10. Design and "As Flown" Radiation Environments for Materials in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Minow, Joseph; McWilliams, Brett; Altstatt, Richard; Koontz, Steven

    2006-01-01

    A conservative design approach was adopted by the International Space Station Program for specifying total ionizing radiation dose requirements for use in selecting and qualifying materials for construction of the International Space Station. The total ionizing dose design environment included in SSP 30512 Space Station Ionizing Radiation Design Environment is based on trapped proton and electron fluence derived from the solar maximum versions of the AE-8 and AP-8 models, respectively, specified for a circular orbit at 500 km altitude and 51.7 degree inclination. Since launch, the range of altitudes utilized for Space Station operations vary from a minimum of approximately 330 km to a maximum of approximately 405 km with a mean operational altitude less than 400 km. The design environment, therefore, overestimates the radiation environment because the particle flux in the South Atlantic Anomaly is the primary contributor to radiation dose in low Earth orbit and flux within the Anomaly is altitude dependent. In addition, a 2X multiplier is often applied to the design environment to cover effects from the contributions of galactic cosmic rays, solar energetic particle events, geomagnetic storms, and uncertainties in the trapped radiation models which are not explicitly included in the design environment. Application of this environment may give radiation dose overestimates on the order of 1OX to 30X for materials exposed to the space environment, suggesting that materials originally qualified for ten year exposures on orbit may be used for longer periods without replacement. In this paper we evaluate the "as flown" radiation environments derived from historical records of the ISS flight trajectory since launch and compare the results with the SSP 30512 design environment to document the magnitude of the radiation dose overestimate provided by the design environment. "As flown" environments are obtained from application of the AE-8/AP-8 trapped particle models along

  11. The Near-Earth Orbital Debris Problem and the Challenges for Environment Remediation

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2012-01-01

    The near-Earth space environment has been gradually polluted with orbital debris (OD) since the beginning of space activities 55 years ago. Although this problem has been known to the research community for decades, the public was, in general, unaware of the issue until the anti-satellite test conducted by China in 2007 and the collision between Cosmos 2251 and the operational Iridium 33 in 2009. The latter also underlined the potential of an ongoing collision cascade effect (the "Kessler Syndrome") in the low Earth orbit (LEO, the region below 2000 km altitude). Recent modeling results have indicated that mitigation measures commonly adopted by the international space community will be insufficient to stabilize the LEO debris population. To better limit the OD population increase, more aggressive actions must be considered. There are three options for OD environment remediation-removal of large/massive intact objects to address the root cause of the OD population growth problem, removal of 5-mm-to-1 cm debris to mitigate the main mission-ending threats for the majority of operational spacecraft, and prevention of major debris-generating collisions as a temporary means to slow down the OD population increase. The technology, engineering, and cost challenges to carry out any of these three options are monumental. It will require innovative ideas, game-changing technologies, and major collaborations at the international level to address the OD problem and preserve the near-Earth environment for future generations.

  12. Experimental Tests of UltraFlex Array Designs in Low Earth Orbital and Geosynchronous Charging Environments

    NASA Technical Reports Server (NTRS)

    Galofaro, Joel T.; Vayner, Boris V.; Hillard, Grover B.

    2011-01-01

    The present ground based investigations give the first definitive look describing the expected on-orbit charging behavior of Orion UltraFlex array coupons in the Low Earth Orbital and Geosynchronous Environments. Furthermore, it is important to note that the LEO charging environment also applies to the International Space Station as well as to the lunar mission charging environments. The GEO charging environment includes the bounding case for all lunar orbital and lunar surface mission environments. The UltraFlex thin film photovoltaic array technology has been targeted to become the sole power system for life support and on-orbit power for the manned Aires Crew Exploration Vehicle. It is therefore, crucial to gain an understanding of the complex charging behavior to answer some of the basic performance and survivability issues in an attempt to ascertain that a single UltraFlex array design will be able to cope with the projected worst case LEO and GEO charging environments. Testing was limited to four array coupons, two coupons each from two different array manufactures, Emcore and Spectrolab. The layout of each array design is identical and varies only in the actual cell technology used. The individual array cells from each manufacturer have an antireflection layered coating and come in two different varieties either uncoated (only AR coating) or coated with a thin conducting ITO layer. The LEO Plasma tests revealed that all four coupons passed the arc threshold -120 V bias tests. GEO electron gun charging tests revealed that only front side area of ITO coated coupons passed tests. Only the Emcore AR array passed backside Stage 2 GEO Tests.

  13. Introducing Earth's Orbital Eccentricity

    ERIC Educational Resources Information Center

    Oostra, Benjamin

    2015-01-01

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

  14. Measured force on elongated bodies in a simulated low-Earth orbit environment

    SciTech Connect

    Maldonado, C. A.; Ketsdever, A. D.; Gimelshein, S. F.

    2014-12-09

    An overview of the development of a magnetically filtered atomic oxygen plasma source and the application of the source to study low-Earth orbit drag on elongated bodies is presented. Plasma diagnostics show that the magnetic filter plasma source produces atomic oxygen ions (O{sup +}) with streaming energies equivalent to the relative orbital environment of approximately 5eV and can supply the appropriate density for LEO simulation. Previous research has demonstrated that momentum transfer between ions and metal surfaces is equivalent to the momentum transfer expected for neutral molecules with similar energy, due to charge exchange occurring prior to momentum transfer. Total drag measurements of aluminum cuboid geometries of varying length to diameter ratios immersed in the extracted plasma plume are presented as a function of streaming ion energy.

  15. Measured force on elongated bodies in a simulated low-Earth orbit environment

    NASA Astrophysics Data System (ADS)

    Maldonado, C. A.; Ketsdever, A. D.; Gimelshein, S. F.

    2014-12-01

    An overview of the development of a magnetically filtered atomic oxygen plasma source and the application of the source to study low-Earth orbit drag on elongated bodies is presented. Plasma diagnostics show that the magnetic filter plasma source produces atomic oxygen ions (O+) with streaming energies equivalent to the relative orbital environment of approximately 5eV and can supply the appropriate density for LEO simulation. Previous research has demonstrated that momentum transfer between ions and metal surfaces is equivalent to the momentum transfer expected for neutral molecules with similar energy, due to charge exchange occurring prior to momentum transfer. Total drag measurements of aluminum cuboid geometries of varying length to diameter ratios immersed in the extracted plasma plume are presented as a function of streaming ion energy.

  16. Proceedings of the NASA Workshop on Atomic Oxygen Effects. [low earth orbital environment

    NASA Technical Reports Server (NTRS)

    Brinza, David E. (Editor)

    1987-01-01

    A workshop was held to address the scientific issues concerning the effects of atomic oxygen on materials in the low Earth orbital (LEO) environment. The program included 18 invited speakers plus contributed posters covering topics such as LEO spaceflight experiments, interaction mechanisms, and atomic oxygen source development. Discussion sessions were also held to organize a test program to evaluate atomic oxygen exposure facilities. The key issues raised in the workshop were: (1) the need to develop a reliable predictive model of the effects of long-term exposure of materials to the LEO environment; (2) the ability of ground-based exposure facilities to provide useful data for development of durable materials; and (3) accurate determination of the composition of the LEO environment. These proceedings include the invited papers, the abstracts for the contributed posters, and an account of the test program discussion sessions.

  17. Improving The Near-Earth Meteoroid And Orbital Debris Environment Definition With LAD-C

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Giovane, F. J.; Corsaro, R. C.; Burchell, M. J.; Drolshagen, G.; Kawai, H.; Tabata, M.; Stansbery, E. G.; Westphal, A. J.; Yano, H.

    2006-01-01

    To improve the near-Earth meteoroid and orbital debris environment definition, a large area particle sensor/collector is being developed to be placed on the International Space Station (ISS). This instrument, the Large Area Debris Collector (LAD-C), will attempt to record meteoroid and orbital debris impact flux, and capture the same particles with aerogel. After at least one year of deployment, the whole system will be brought back for additional laboratory analysis of the captured meteoroids and orbital debris. This project is led by the U.S. Naval Research Laboratory (NRL) while the U.S. Department of Defense (DoD) Space Test Program (STP) is responsible for the integration, deployment, and retrieval of the system. Additional contributing team members of the consortium include the NASA Orbital Debris Program Office, JAXA Institute of Space and Astronautical Science (ISAS), Chiba University (Japan), ESA Space Debris Office, University of Kent (UK), and University of California at Berkeley. The deployment of LAD-C on the ISS is planned for 2008, with the system retrieval in late 2009.

  18. Simulation and analysis of the LUCID experiment in the Low Earth Orbit radiation environment

    NASA Astrophysics Data System (ADS)

    Whyntie, T.; Harrison, M. A.

    2014-06-01

    The Langton Ultimate Cosmic ray Intensity Detector (LUCID) experiment is a satellite-based device that will use five Timepix hybrid silicon pixel detectors to make measurements of the radiation environment at an altitude of approximately 635 km, i.e. in Low Earth Orbit (LEO). The experiment is due to launch aboard Surrey Satellite Technology Limited's (SSTL's) TechDemoSat-1 in 2014. The Timepix detectors, developed by the Medipix Collaboration, are arranged to form the five sides of a cube enclosed by a 0.7 mm thick aluminium "dome", and will be operated in Time-over-Threshold mode to allow the flux, energy and directionality of incident ionising radiation to be measured. To estimate the anticipated data rates with respect to these measurements, the LUCID experiment has been modelled using the GEANT4 software framework. As an input to these simulations, SPENVIS, ESA's Space Environment information system, was used to obtain the estimated flux of trapped protons and electrons in TechDemoSat-1's orbit with NASA's AP-8 and AE-8 models. A web portal, LUCIDITY, was developeded to allow school students from the LUCID Collaboration to manage SPENVIS flux spectra and GEANT4 input cards. The initial results reported here confirm that the LUCID's data transmission allowance is sufficient, and further work applying the techniques to more specific space radiation environments with a more sophisticated simulation is proposed.

  19. Long-term performance of precision crystal oscillators in a near-Earth orbital environment.

    PubMed

    Rueger, L J; Norton, J R; Lasewicz, P T

    1993-01-01

    The Navy Navigation Satellite System (NNSS) uses precision quartz crystal oscillators to provide time and frequency in the orbiting spacecraft. The frequency changes for multiple oscillators, which were observed for 28 years of operational service in the orbital environment, are discussed. The primary frequency changes are believed to be caused by mass transfer to and from the resonator, stress relief in the resonator mounting structure and electrodes, and ionizing radiation of the quartz resonator. Observations to a resolution of 10- 13 have been made from 1963 to 1991 on 20 operational satellites in near-Earth orbit. No oscillator failures have occurred during the entire program life of nearly 30 years. One oscillator provided continuous operational service for over 21 years, and several have served more than 15 years. No oscillator changed frequency more than two parts in 107 while in operational service. One of the best performing oscillators had a predictable drift rate of 9x10(-13)+/-1x10(-13) per day after three years of service. PMID:18263216

  20. Introducing Earth's Orbital Eccentricity

    NASA Astrophysics Data System (ADS)

    Oostra, Benjamin

    2015-12-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is small, and its only effect on the seasons is their unequal durations. Here I show a pleasant way to guide students to the actual value of Earth's orbital eccentricity, starting from the durations of the four seasons. The date of perihelion is also found.

  1. Full simulation of the LUCID experiment in the Low Earth Orbit radiation environment

    NASA Astrophysics Data System (ADS)

    Whyntie, T.; Harrison, M. A.

    2015-03-01

    The Langton Ultimate Cosmic ray Intensity Detector (LUCID) experiment is a satellite-based device that uses five Timepix hybrid silicon pixel detectors to make measurements of the radiation environment at an altitude of approximately 630 km, i.e. in Low Earth Orbit (LEO) . The experiment launched aboard Surrey Satellite Technology Limited's (SSTL's) TechDemoSat-1 on Tuesday the 8th of July 2014. The Timepix detectors, developed by the Medipix2 Collaboration, are arranged to form the five sides of a cube enclosed by a 0.7 mm thick aluminium covering, and are operated in Time-over-Threshold (ToT) mode to allow the flux, energy and directionality of incident ionising radiation to be measured. To understand the expected detector performance with respect to these measurements, the LUCID experiment has been modelled using the Allpix software package, a generic simulation toolkit for silicon pixel detectors built upon the GEANT4 framework. The work presented here summarises studies completed using the GridPP Collaboration's computing grid infrastructure to perform the simulations, store the resultant datasets, and share that data with the LUCID Collaboration. The analysis of these datasets has given an indication of the expected performance in differing space radiation environments (for example, during passes of the polar regions or the South Atlantic Anomaly), and has allowed the LUCID Collaboration to prepare for when data is transmitted back to Earth in late 2014.

  2. Investigating fundamental physics and space environment with a dedicated Earth-orbiting spacecraft

    NASA Astrophysics Data System (ADS)

    Peron, Roberto

    The near-Earth environment is a place of first choice for performing fundamental physics experiments, given its proximity to Earth and at the same time being relatively quiet dynamically for particular orbital arrangements. This environment also sees a rich phenomenology for what concerns gravitation. In fact, the general theory of relativity is an incredibly accurate description of gravitational phenomenology. However, its overall validity is being questioned by the theories that aim at reconciling it with the microscopic domain. Challenges come also from the ‘mysteries’ of Dark Matter and Dark Energy, though mainly at scales from the galactic up to the cosmological. It is therefore important to precisely test the consequences of the theory -- as well as those of competing ones -- at all the accessible scales. At the same time, the development of high-precision experimental space techniques, which are needed for tests in fundamental physics, opens the way to complementary applications. The growth of the (man-made) orbital debris population is creating problems to the future development of space. The year 2009 witnessed the first accidental collision between two satellites in orbit (Iridium and Cosmos) that led to the creation of more debris. International and national agencies are intervening by issuing and/or adopting guidelines to mitigate the growth of orbital debris. A central tenet of these guidelines requires a presence in space shorter than 25 years to satellites in low Earth orbit (LEO) after the conclusion of their operational lives. However, the determination of the natural lifetime of a satellite in LEO is very uncertain due to a large extent to the short-term and long-term variability of the atmospheric density in LEO and the comparatively low-accuracy of atmospheric density models. Many satellites orbiting in the 500-1200 km region with circular or elliptical orbits will be hard pressed to establish before flight whether or not they meet the 25

  3. The viscoelastic characterization of polymer materials exposed to the low-Earth orbit environment

    NASA Technical Reports Server (NTRS)

    Strganac, Thomas; Letton, Alan

    1992-01-01

    Recent accomplishments in our research efforts have included the successful measurement of the thermal mechanical properties of polymer materials exposed to the low-earth orbit environment. In particular, viscoelastic properties were recorded using the Rheometrics Solids Analyzer (RSA 2). Dynamic moduli (E', the storage component of the elastic modulus, and E'', the loss component of the elastic modulus) were recorded over three decades of frequency (0.1 to 100 rad/sec) for temperatures ranging from -150 to 150 C. Although this temperature range extends beyond the typical use range of the materials, measurements in this region are necessary in the development of complete viscoelastic constitutive models. The experimental results were used to provide the stress relaxation and creep compliance performance characteristics through viscoelastic correspondence principles. Our results quantify the differences between exposed and control polymer specimens. The characterization is specifically designed to elucidate a constitutive model that accurately predicts the change in behavior of these materials due to exposure. The constitutive model for viscoelastic behavior reflects the level of strain, the rate of strain, and the history of strain as well as the thermal history of the material.

  4. Spacecraft plume interactions with the magnetosphere plasma environment in geostationary Earth orbit

    NASA Astrophysics Data System (ADS)

    Stephani, K. A.; Boyd, I. D.

    2016-02-01

    Particle-based kinetic simulations of steady and unsteady hydrazine chemical rocket plumes are presented in a study of plume interactions with the ambient magnetosphere in geostationary Earth orbit. The hydrazine chemical rocket plume expands into a near-vacuum plasma environment, requiring the use of a combined direct simulation Monte Carlo/particle-in-cell methodology for the rarefied plasma conditions. Detailed total and differential cross sections are employed to characterize the charge exchange reactions between the neutral hydrazine plume mixture and the ambient hydrogen ions, and ion production is also modeled for photoionization processes. These ionization processes lead to an increase in local plasma density surrounding the spacecraft owing to a partial ionization of the relatively high-density hydrazine plume. Results from the steady plume simulations indicate that the formation of the hydrazine ion plume are driven by several competing mechanisms, including (1) local depletion and (2) replenishing of ambient H+ ions by charge exchange and thermal motion of 1 keV H+ from the ambient reservoir, respectively, and (3) photoionization processes. The self-consistent electrostatic field forces and the geostationary magnetic field have only a small influence on the dynamics of the ion plume. The unsteady plume simulations show a variation in neutral and ion plume dissipation times consistent with the variation in relative diffusion rates of the chemical species, with full H2 dissipation (below the ambient number density levels) approximately 33 s after a 2 s thruster burn.

  5. High temperature radiator materials for applications in the low Earth orbital environment

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Banks, Bruce A.; Mirtich, Michael J.; Lebed, Richard; Brady, Joyce; Hotes, Deborah; Kussmaul, Michael

    1987-01-01

    Radiators must be constructed of materials which have high emittance in order to efficiently radiate heat from high temperature space power systems. In addition, if these radiators are to be used for applications in the low Earth orbital environment, they must not be detrimentally affected by exposure to atomic oxygen. Four materials selected as candidate radiator materials (304 stainless steel, copper, titanium-6% aluminum-4% vanadium (Ti-6%Al-4%V), and niobium-1% zirconium (Nb-1%Zr)) were surface modified by acid etching, heat treating, abrading, sputter texturing, electrochemical etching, and combinations of the above in order to improve their emittance. Combination treatment techniques with heat treating as the second treatment provided about a factor of two improvement in emittance for 304 stainless steel, Ti-6%Al-4%V, and Nb-1%Zr. A factor of three improvement in emittance occurred for discharge chamber sputter textured copper. Exposure to atomic oxygen in an RF plasma asher did not significantly change the emittance of those samples that had been heat treated as part of their texturing process. An evaluation of oxygen penetration is needed to understand how oxidation affects the mechanical properties of these materials when heat treated.

  6. High temperature radiator materials for applications in the low Earth orbital environment

    SciTech Connect

    Rutledge, S.K.; Banks, B.A.; Mirtich, M.J.; Lebed, R.; Brady, J.; Hotes, D.; Kussmaul, M.

    1994-09-01

    Radiators must be constructed of materials which have high emittance in order to efficiently radiate heat from high temperature space power systems. In addition, if these radiators are to be used for applications in the low Earth orbital environment, they must not be detrimentally affected by exposure to atomic oxygen. Four materials selected as candidate radiator materials 304 stainless steel, copper, titanium-6% aluminum-4% vanadium (Ti-6%Al-4%V), and niobium-1% zirconium (Nb-1%Zr) were surface modified by acid etching, heat treating, abrading, sputter texturing, electrochemical etching, and combinations of the above in order to improve their emittance. Combination treatment techniques with heat treating as the second treatment provided about a factor of two improvement in emittance for 304 stainless steel, Ti-6%Al-4%V, and Nb-1%Zr. A factor of three improvement in emittance occurred for discharge chamber sputter textured copper. Exposure to atomic oxygen in RF plasma asher did not significantly change the emittance of those samples that had been heat treated as part of their texturing process. An evaluation of oxygen penetration is needed to understand how oxidation affects the mechanical properties of these materials when heat treated.

  7. A model of the near-earth plasma environment and application to the ISEE-A and -B orbit

    NASA Technical Reports Server (NTRS)

    Chan, K. W.; Sawyer, K. W.; Vette, J. I.

    1977-01-01

    A model of the near-earth environment to obtain a best estimate of the average flux of protons and electrons in the energy range from 0.1 to 100 keV for the International Sun-Earth Explorer (ISEE)-A and -B spacecraft. The possible radiation damage to the thermal coating on these spinning spacecraft is also studied. Applications of the model to other high-altitude satellites can be obtained with the appropriate orbit averaging. This study is the first attempt to synthesize an overall quantitative environment of low-energy particles for high altitude spacecraft, using data from in situ measurements.

  8. Low Earth Orbiter: Terminal

    NASA Technical Reports Server (NTRS)

    Kremer, Steven E.; Bundick, Steven N.

    1999-01-01

    In response to the current government budgetary environment that requires the National Aeronautics and Space Administration (NASA) to do more with less, NASA/Goddard Space Flight Center's Wallops Flight Facility has developed and implemented a class of ground stations known as a Low Earth Orbiter-Terminal (LEO-T). This development thus provides a low-cost autonomous ground tracking service for NASA's customers. More importantly, this accomplishment provides a commercial source to spacecraft customers around the world to purchase directly from the company awarded the NASA contract to build these systems. A few years ago, NASA was driven to provide more ground station capacity for spacecraft telemetry, tracking, and command (TT&C) services with a decreasing budget. NASA also made a decision to develop many smaller, cheaper satellites rather than a few large spacecraft as done in the past. In addition, university class missions were being driven to provide their own TT&C services due to the increasing load on the NASA ground-tracking network. NASA's solution for this ever increasing load was to use the existing large aperture systems to support those missions requiring that level of performance and to support the remainder of the missions with the autonomous LEO-T systems. The LEO-T antenna system is a smaller, cheaper, and fully autonomous unstaffed system that can operate without the existing NASA support infrastructure. The LEO-T provides a low-cost, reliable space communications service to the expanding number of low-earth orbiting missions around the world. The system is also fostering developments that improve cost-effectiveness of autonomous-class capabilities for NASA and commercial space use. NASA has installed three LEO-T systems. One station is at the University of Puerto Rico, the second system is installed at the Poker Flat Research Range near Fairbanks, Alaska, and the third system is installed at NASA's Wallops Flight Facility in Virginia. This paper

  9. The effect of the low Earth orbit environment on space solar cells: Results of the Advanced Photovoltaic Experiment (S0014)

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Hickey, John R.; Scheiman, David A.

    1993-01-01

    The results of post-flight performance testing of the solar cells flown on the Advanced Photovoltaic Experiment are reported. Comparison of post-flight current-voltage characteristics with similar pre-flight data revealed little or no change in solar cell conversion efficiency, confirming the reliability and endurance of space photovoltaic cells. This finding is in agreement with the lack of significant physical changes in the solar cells despite nearly six years in the low Earth orbit environment.

  10. Charged particle radiation environment for the Spacelab and other missions in low earth orbit, revision A

    NASA Technical Reports Server (NTRS)

    Watts, J. W., Jr.; Wright, J. J.

    1976-01-01

    The physical charged particle dose to be encountered in low earth orbit Spacelab missions is estimated for orbits of inclinations from e8.5 to 90 deg and altitudes from 200 to 800 km. The dose encountered is strongly altitude dependent, with a weaker dependence on inclination. Doses range from 0.007 rads/day at 28.5 deg and 200 km to 1.57 rads/day at 28.5 deg and 800 km behind a 5.0 g/sq cm shield. Geomagnetically trapped protons were the primary source of damage over most of the range of altitudes and inclinations, with galactic cosmic rays making a significant contribution at the lowest altitudes.

  11. The Predicted Growth of the Low Earth Orbit Space Debris Environment: An Assessment of Future Risk for Spacecraft

    NASA Technical Reports Server (NTRS)

    Krisko, Paula H.

    2007-01-01

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

  12. 'Spider' in Earth Orbit

    NASA Technical Reports Server (NTRS)

    1969-01-01

    View of the Apollo 9 Lunar Module 'Spider' in a lunar landing configuration photographed by Command Module pilot David Scott inside the Command/Service Module 'Gumdrop' on the fifth day of the Apollo 9 earth-orbital mission. The landing gear on 'Spider' has been deployed. lunar surface probes (sensors) extend out from the landing gear foot pads. Inside the 'Spider' were astronauts James A. McDivitt, Apollo 9 Commander; and Russell L. Schweickart, Lunar Module pilot.

  13. Validation of the new trapped environment AE9/AP9/SPM at low Earth orbit

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.

    2014-09-01

    The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS. At LEO, a vehicle encounters exposure from trapped particles and attenuated galactic cosmic rays (GCR). Within the trapped field, a challenge arises from properly estimating the amount of exposure acquired. There exist a number of models to define the intensities of the trapped particles during the solar quiet and active times. At active times, solar energetic particles (SEP) generated by solar flare or coronal mass ejection (CME) also contribute to the exposure at high northern and southern latitudes. Among the more established trapped models are the historic and popular AE8/AP8, dating back to the 1980s, the historic and less popular CRRES electron/proton, dating back to 1990s and the recently released AE9/AP9/SPM. The AE9/AP9/SPM model is a major improvement over the older AE8/AP8 and CRRES models. This model is derived from numerous measurements acquired over four

  14. Earth Co-orbital Objects

    NASA Astrophysics Data System (ADS)

    Wiegert, P.; Connors, M.; Chodas, P.; Veillet, C.; Mikkola, S.; Innanen, K.

    2002-12-01

    The recent discovery of asteroid 2002 AA29 by the LINEAR survey and the realization of its co-orbital relationship with Earth lead us to consider the characteristics of Earth Co-orbital Objects (ECOs) in general. An object with semimajor axis between 0.99 and 1.01 AU is in 1:1 resonance with the Earth. To be co-orbital in the sense of moving along the Earth's orbit, an object must further have its other orbital parameters similar to those of the Earth. Clarification is needed as to what range of orbital parameters can be regarded as similar enough to permit classification as an ECO. ECOs would be expected to librate on tadpole or horseshoe orbits, be relatively easy to access with spacecraft, and to sometimes exhibit quasisatellite behavior. 2002 AA29 is on a horseshoe orbit and was discovered in a general asteroid survey while near Earth at one end of the horseshoe orbit. Searches for Earth Trojan asteroids, which would be members of the ECO class on tadpole orbits near a triangular Lagrange Point, have not yet been successful. While 2002 AA29 has an orbit even less eccentric than Earth's, it has an inclination of about 10 degrees. 2000 PH5 and 2001 GO2 are on horseshoe orbits and interact gravitationally with Earth to 'bounce' when they approach the Earth from either side. With eccentricities of .23 and .17 respectively, they do not have decidedly Earth-like orbits despite inclinations less that 5 degrees. When in quasi-satellite mode, a body exhibits a looping motion relative to Earth in some ways resembling a satellite orbit. Several resonant bodies including 3753 Cruithne exhibit this behavior at times, but ECOs remain close to Earth while doing it. We suggest that directed searches be used to discover ECOs and characterize this class of objects. Orbital simulations suggest the best target spaces, which are only partially covered by present general searches.

  15. The long-term implications of operating satellite constellations in the low earth orbit debris environment

    NASA Astrophysics Data System (ADS)

    Walker, R.; Crowther, R.; Swinerd, G. G.

    1997-05-01

    DRA's Integrated Debris Evolution Suite (IDES) model is used in this study to predict the future evolution of the orbital debris environment for two distinct scenarios. For the first case, a pre-generated background debris population for 1995 and `business as usual' future launch/explosion rates are used as input to the model. IDES then employs its collision event prediction algorithm to simulate evolution from 1996 to 2020 as a baseline. The second scenario uses the same initial conditions and future trends, but in addition, a large constellation is introduced into the simulation process from year 1998 onwards. The additional contribution of the constellation to the temporal variation of key environment/population parameters is presented; including enhancement from any long-term collision coupling effects.

  16. The effect of the low Earth orbit environment on space solar cells: Results of the advanced photovoltaic experiment (S0014)

    NASA Technical Reports Server (NTRS)

    Brinker, David J.; Hickey, John R.

    1992-01-01

    The Advanced Photovoltaic Experiment (APEX), containing over 150 solar cells and sensors, was designed to generate laboratory reference standards as well as to explore the durability of a wide variety of space solar cells. Located on the leading edge of the Long Duration Exposure Facility (LDEF), APEX received the maximum possible dosage of atomic oxygen and ultraviolet radiation, as well as enormous numbers of impacts from micrometeoroids and debris. The effect of the low earth orbital (LEO) environment on the solar cells and materials of APEX will be discussed in this paper. The on-orbit performance of the solar cells, as well as a comparison of pre- and postflight laboratory performance measurements, will be presented.

  17. Evaluation and prediction of the degradation of space Si solar cells induced by a low-earth-orbit radiation environment

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Yang, Sheng-Sheng; Feng, Zhan-Zu; Zhang, Lei

    2012-09-01

    Space-graded silicon solar cells are evaluated by 1 MeV and 2 MeV electron-irradiation. The mean degradation of the maximum power (Pmax) is presented and analyzed. The degradation at both electron energies has been correlated with the displacement damage dose (Dd). A good linearity between the electron Dd and the mean Pmax degradation is obtained. The concept of Dd has also been used to predict the Si solar cell response in a low-earth-orbit (Altitude 799 km, Inclination 99°) radiation environment, considering the shielded effect of a 120 μm-thick silica coverglass on reducing the radiation. Compared with the on-orbit data from a Si solar array of a Chinese satellite (duration from April 2007 to July 2010), a good match can be found between the on-orbit data and the predicted results using Dd methodology, indicating the method is appropriate for evaluating the radiation damage of the solar cells, and also to provide a new technique for studying radiation effects on the optoelectronic detectors used in many high energy physics applications, where harsh radiation environments produce damage in optoelectronic device materials.

  18. Monitoring Variations to the Near-Earth Space Environment during High Solar Activity Using Orbiting Rocket Bodies

    NASA Astrophysics Data System (ADS)

    Romero, V.; Ryan, W.; Ryan, E.

    A space object's general characteristics can be substantially influenced by changes in the magnetosphere, ionosphere, and thermosphere environments. These space weather effects can vary according to the space object's orbit, position relative to certain regions in space, the severity of solar activity, and many other factors. Outcomes can range from minor and easily recoverable to total breakdown. Further, technology has advanced such that satellite components have become smaller and smaller, and these micro-systems are increasingly more susceptible to the highly energetic solar particles associated with intense activity. Therefore, additional study of the significance of space weather events on Earth-orbiting objects would be beneficial. A rotating rocket body in orbit experiences a magnetic torque due to the Earth's magnetic field that results in an exponential decay of its rotational frequency and a variation on the axis of rotation. The Photometric Periods of Artificial Satellites (McCants, 2007) database consists of over 60,000 period measurements, mostly visually acquired, dating back to 1958. Although this database validates this predicted exponential decay in rotation rate, many anomalies have been observed, including increased rotational frequencies. Theories for the causes of these anomalies range from leaking fuel tanks to interaction with the local space environment. Our program aims to complement the current visual database through CCD and video photometric observations of rotating rocket bodies using a portable 0.35-meter telescope and the Magdalena Ridge Observatory's 2.4-meter telescope. The goal is to generate a detailed astrometric and photometric database for a small set of targets at different orbital altitudes in order to study the variability in orbital motion and the rotational angular momentum vector, particularly during times of high solar activity. The National Oceanic and Atmospheric Administration (NOAA) provides daily information and

  19. The Performance of Silicon Solar Cells Exposed to a Simulated Low Earth Orbit Plasma Environment: Laboratory Ground Tests

    NASA Astrophysics Data System (ADS)

    Abd El-Hameed, Afaf M.; Sabry, M.; Ghitas, Ahmed; El-Tokhy, Fatma S.; Schlosser, Viktor

    2015-12-01

    We have studied the effects of a low earth orbit (LEO) plasma environment on the performance of solar cells. Laboratory ground tests were used to simulate the properties of a low-energy LEO plasma. A Penning plasma source was used to generate plasma from an argon (Ar) gas flow at low pressure (˜10-5 torr) through a vacuum chamber. Diagnostic tools were used to investigate the plasma conditions and their effects on six silicon (Si) solar cells located in the chamber. Alternating current conditions for both biased and unbiased monocrystalline Si solar cells produced from n/ p terrestrial cells with deep junctions were investigated after exposure to plasma fluence for different times up to 14 h. The results obtained confirmed variation of the performance of the cells samples as a consequence of exposure to the plasma.

  20. Oxidation and protection of fiberglass-epoxy composite masts for photovoltaic arrays in the low earth orbital environment

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Ciancone, Michael L.; Paulsen, Phillip E.; Brady, Joyce A.

    1988-01-01

    The extent of degradation of fiberglass-epoxy composite masts of the Space Station solar array panel, when these are exposed to atomic oxygen environment of the low-earth orbit, was investigated in ground testing of fiberglass-epoxy composites in an RF plasma asher. In addition, several methods of protecting the composite structures were evaluated, including an aluminum braid covering, an In-Sn eutectic, and a silicone based paint. It was found that, during exposure, the epoxy at the surface of the composite was oxidized, exposing individual glass fibers which could easily be removed. The results of mass measurements and SEM examination carried out after thermal cycling and flexing of exposed composite samples indicated that coatings such as In-Sn eutectic may provide adequate protection by containing the glass fibers, even though mass loss still occurs.

  1. Improving the Near-Earth Micrometeoroid and Orbital Debris Environment Definition with LADC

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Giovane, F.; Corsaro, R.; Stansbery, E.

    2006-01-01

    The Large Area Debris Collector (LADC) is a 10 m(sup 2) aerogel and acoustic sensor system designed to characterize and collect submillimeter micrometeoroids and orbital debris on the International Space Station (ISS). The project is led by the U.S. Naval Research Laboratory (NRL) with major collaboration by the NASA Orbital Debris Program Office at Johnson Space Center. The U.S. Department of Defense Space Test Program (STP) is responsible for the integration, deployment, and retrieval of the system. The deployment is scheduled for August 2007 with an orbital collection period of one to two years. The combined area time product of LADC will provide a much needed orbital debris population update in the size regime that is important to the safety community - 100 mm and larger. Another key element for LADC is the source identification of the collected samples. Impact features such as track length and track volume can be used to estimate the impact speed and direction of any selected residual embedded in aerogel. Acoustic sensors can provide impact timing and impact location information. The combined dynamical signatures make it possible to reconstruct the orbits of some of the collected samples and lead to their source identification. Compositional analysis on the residuals can also separate debris from meteoroids and provide additional population breakdown for orbital debris (e.g., Al, paint, steel, Al2O3). To maximize the science return and minimize potential contamination from other ISS modules, a careful selection of the location and orientation of LADC on the ISS is needed. Key issues and engineering constraints encountered during mission preparation, and the expected science return based on the mission configuration, are summarized in this paper.

  2. Oxidation and protection of fiberglass-epoxy composite masts for photovoltaic arrays in the low Earth orbital environment

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Paulsen, Phillip E.; Brady, Joyce A.; Ciancone, Michael L.

    1988-01-01

    Fiberglass-epoxy composites are considered for use as structural members for the mast of the space station solar array panel. The low Earth orbital environment in which space station is to operate is composed mainly of atomic oxygen, which has been shown to cause erosion of many organic materials and some metals. Ground based testing in a plasma asher was performed to determine the extent of degradation of fiberglass-epoxy composites when exposed to a simulated atomic oxygen environment. During exposure, the epoxy at the surface of the composite was oxidized, exposing individual glass fibers which could easily be removed. Several methods of protecting the composite were evaluated in an atomic oxygen environment and with thermal cycling and flexing. The protection techniques evaluated to date include an aluminum braid covering, an indium-tin eutectic and a silicone based paint. The open aluminum braid offered little protection while the CV-1144 coating offered some initial protection against atomic oxygen, but appears to develop cracks which accelerate degradation when flexed. Coatings such as the In-Sn eutectic may provide adequate protection by containing the glass fibers even though mass loss still occurs.

  3. Space and Atmospheric Environments: From Low Earth Orbits to Deep Space

    NASA Technical Reports Server (NTRS)

    Barth, Janet L.

    2003-01-01

    Natural space and atmospheric environments pose a difficult challenge for designers of technological systems in space. The deleterious effects of environment interactions with the systems include degradation of materials, thermal changes, contamination, excitation, spacecraft glow, charging, radiation damage, and induced background interference. Design accommodations must be realistic with minimum impact on performance while maintaining a balance between cost and risk. The goal of applied research in space environments and effects is to limit environmental impacts at low cost relative to spacecraft cost and to infuse enabling and commercial off-the-shelf technologies into space programs. The need to perform applied research to understand the space environment in a practical sense and to develop methods to mitigate these environment effects is frequently underestimated by space agencies and industry. Applied science research in this area is critical because the complexity of spacecraft systems is increasing, and they are exposed simultaneously to a multitude of space environments.

  4. Aqua satellite orbiting the Earth

    NASA Video Gallery

    This animation shows the Aqua satellite orbiting the Earth on August 27, 2005 by revealing MODIS true-color imagery for that day. This animation is on a cartesian map projection, so the satellite w...

  5. Lunar Orbiter: Moon and Earth

    NASA Technical Reports Server (NTRS)

    1966-01-01

    The worlds first view of the Earth taken by a spacecraft from the vicinity of the Moon. The photo was transmitted to Earth by the United States Lunar Orbiter I and recieved at the NASA tracking station at Robledo de Chavela near Madrid, Spain. This crescent of the Earth was photographed August 23 at 16:35 GMT when the spacecraft was on its 16th orbit and just about to pass behind the Moon. This is the view the astronauts will have when they come around the backside of the Moon and face the Earth. The Earth is shown on the left of the photo with the U.S. east coast in the upper left, southern Europe toward the dark or night side of the Earth, and Antartica at the bottom of the Earth crescent. The surface of the Moon is shown on the right side of the photograph.

  6. Lunar Orbiter I - Moon & Earth

    NASA Technical Reports Server (NTRS)

    1966-01-01

    First view of the earth and moon from space. Published in: Spaceflight Revolution: Langley Research Center From Sputnik to Apollo, by James R. Hansen. NASA History Series. NASA SP ; 4308. p ii. Caption: 'The picture of the century was this first view of the earth from space. Lunar Orbiter I took the photo on 23 August 1966 on its 16th orbit just before it passed behind the moon. The photo also provided a spectacular dimensional view of the lunar surface.'

  7. The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes

    NASA Astrophysics Data System (ADS)

    Fioretti, V.; Bulgarelli, A.; Malaguti, G.; Bianchin, V.; Trifoglio, M.; Gianotti, F.

    2012-07-01

    The background minimization is a science-driven necessity in order to reach deep sensitivity levels in the hard X-ray band, one of the key scientific requirements for hard X-ray telescopes (e.g. NuSTAR, ASTRO-H). It requires a careful modeling of the radiation environment and new concepts of shielding systems. We exploit the Bologna Geant4 Multi-Mission Simulator (BoGEMMS) features to evaluate the impact of the Low Earth Orbit (LEO) radiation environment on the prompt background level for a hybrid Si/CdTe soft and hard X-ray detection assembly and a combined active and passive shielding system. For each class of particles, the spectral distribution of the background flux is simulated, exploring the effect of different materials (plastic vs inorganic active scintillator) and configurations (passive absorbers enclosing or surrounded by the active shielding) on the background count rate. While protons are efficiently removed by the active shielding, an external passive shielding causes the albedo electrons and positrons to be the primary source of background. Albedo neutrons are instead weakly interactive with the active shielding, and they cause an intense background level below 10 keV via elastic scattering. The best shielding configuration in terms of background and active shielding count rates is given by an inorganic scintillator placed inside the passive layers, with the addition of passive material to absorb the intense fluorescence lines of the active shielding and avoid escape peaks on the CdTe detector.

  8. Design and "As Flown" Radiation Environments for Materials in Low Earth Orbits

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Altstatt, Richard L.; McWilliams, Brett; Koontz, Steven L.

    2006-01-01

    The design estimate for the materials for the International Space Station (ISS) specified in SSP 30512 was a conservative estimate. The environment dose was over estimated. The materials originally qualified for approximately 10-15 years are anticipated to be acceptable for periods of up to 20-30 years based on SSP-30512 or 40-60 years based on 2x SSP-30512. This viewgraph presentation shows charts and graphs that review the altitude, the solar minimum and maximum, and the radiation exposure of other satellite, among other graphics.

  9. The definition of the low earth orbital environment and its effect on thermal control materials

    NASA Technical Reports Server (NTRS)

    Durcanin, J. T.; Chalmers, D. R.; Visentine, J. T.

    1987-01-01

    The LEO environment and its effects on thermal-control materials (TCMs) being evaluated for use in long-term-mission space structures such as the Space Station are characterized, summarizing the results of recent space and laboratory experiments. Factors examined include atomic oxygen (a serious problem out to 600-700 km), ionizing radiation, solar UV radiation, solid particles (manmade debris and micrometeoroids, a significant hazard out to about 1000 km), and synergistic effects. Numerical data on the expected intensity of these effects for the different Space Station components, the resistance of specific TCMs to the effects, and the effectiveness of protective coatings are compiled in extensive tables and illustrated with diagrams, graphs, and micrographs.

  10. The effects of simulated low Earth orbit environments on spacecraft thermal control coatings

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Rutledge, Sharon K.; Bruckner, Eric J.; Stidham, Curtis R.; Stueber, Thomas J.; Booth, Roy E.

    1993-01-01

    Candidate Space Station Freedom radiator coatings including Z-93, YB-71, anodized aluminum and SiO(x) coated silvered Teflon have been characterized for optical properties degradation upon exposure to environments containing atomic oxygen, vacuum ultraviolet (VUV) radiation, and/or silicone contamination. YB-71 coating showed a blue-gray discoloration, which has not been observed in space, upon exposure in atomic oxygen facilities which also provide exaggerated VUV radiation. This is evidence that damage mechanisms occur in these ground laboratory facilities which are different from those which occur in space. Radiator coatings exposed to an electron cyclotron resonance (ECR) atomic oxygen source in the presence of silicone-containing samples showed severe darkening from the intense VUV radiation provided by the ECR and from silicone contamination. Samples exposed to atomic oxygen from the ECR source and to VUV lamps, simultaneously, with in situ reflectance measurement, showed that significantly greater degradation occurred when samples received line-of-site ECR beam exposure than when samples were exposed to atomic oxygen scattered off of quartz surfaces without line-of-site view of the ECR beam. For white paints, exposure to air following atomic oxygen/VUV exposure reversed the darkening due to VUV damage. This illustrates the importance of in situ reflectance measurement.

  11. Twenty Years of Radiation Measurements in Low-Earth Orbit - What Have We Learned Space Radiation Environment?

    NASA Technical Reports Server (NTRS)

    Golightly, Michael J.; Weyland, Mark D.; Johnson, A. S.; Semones, E.

    2001-01-01

    The advent of the Space Shuttle program has made possible space radiation environment measurements spanning a wide range of altitudes and orbital inclinations over multiple solar cycles. These measurements range from routine integral dose measurements with thermoluminescent dosimeters to particle energy spectra measurements made with a charged particle telescope. This paper will review the new understanding about the space radiation environment gained from this diverse data set. Major findings from these measurements include: estimations of the westward drift rate of the South Atlantic Anomaly (SAA) of 0.28-0.49/y; evidence for a northward component to the SAA drift of 0.08-0.12/y; observation of the formation and decay of the pseudo-stable additional radiation belt following the Mar 1991 SPE and geomagnetic storm with an estimated decay e-folding time of 9-10 months; observation of a local geomagnetic east-west trapped proton exposure anisotropy with an estimated magnitude of 1.6-3.3; demonstration that the trapped proton exposure in low-Earth orbit (LEO) can be reasonably modeled as a power law function of atmospheric density in the SAA region, with best correlations obtained when the exospheric temperature saturates at 938-975 K; the actual solar cycle modulation of trapped proton exposure in LEO is less than predicted by the AP8 model; and the testing and validation of GCR flux models, radiation transport codes, and dynamic geomagnetic cutoff models. Long-term, time-resolved proportional counter measurements made aboard the Mir during the same period provides further demonstration of the solar cycle modulation of the trapped protons at low altitudes - the observed modulation is also well described as power law function of atmospheric density. These data and findings have helped to improve the overall accuracy of pre-mission crew exposure projections using various semi-empirical space environment models, radiation transport codes, and spacecraft radiation

  12. Electrodynamics of the Plasma Environment Induced around Spacecraft in Low Earth Orbit: Three-Dimensional Theory and Numerical Modeling.

    NASA Astrophysics Data System (ADS)

    Gatsonis, Nikolaos Achilleas

    A study is presented of the electrodynamic interactions within the plasma environment induced around spacecraft in Low Earth Orbit. A fully three-dimensional theory and a computational model is developed for an artificial plasma cloud created by spacecraft with the potential of releasing neutrals and/or plasma into the ambient ionosphere. A fluid model for the plasma transport is derived. The forces included in the momentum balance are due to electric fields, pressure, gravity, drag due to collisions and perturbative inertia terms. The Flux Corrected Transport (FCT) scheme is used for the numerical solution of the hyperbolic continuity equations. This approach limits the artificial dissipation or dispersion arising in the numerical solution. The 3D -FCT algorithm, and the stability characteristics of the high and low order schemes used in the FCT are discussed. The equation for the electrostatic potential is a three-dimensional nonself-adjoint elliptic equation with highly dissimilar coefficients. The numerical solution of the resulting large, sparse, asymmetric system of equations is discussed. Initial time numerical simulations are performed. A water-bag plasma cloud model is used to demonstrate the current coupling process. For neutral densities higher than the ambient the plasma cloud develops a transverse drift of the order of the orbital velocity. Simulations of typical spacecraft operations are performed and the created water plasma cloud is studied. It is shown that the flow of neutrals is in the free molecular regime. The effects of altitude of the release, orientation of the thrust vector with regard to the magnetic field, and latitude are considered. It is shown that a large water ion cloud is formed with densities of the order of the ambient oxygen ions. The ultraviolet radiation emission is shown to modify the signature of the spacecraft. The model predicts qualitatively most of the observations. Quantitatively predictions are within the measured

  13. Dynamics of Earth orbiting formations

    NASA Technical Reports Server (NTRS)

    Ploen, Scott R.; Scharf, Daniel P.; Hadaegh, Fred Y.; Acikmese, Ahmed B.

    2004-01-01

    In this paper the equations of motion of a formation consisting of n spacecraft in Earth orbit are derived via Lagrange's equations. The equations of motion of the formation are developed with respect to both (1) a bound Keplerian reference orbit, and (2) a specific spacecraft in the formation. The major orbital perturbations acting on a formation in low Earth orbit are also included in the analysis. In contrast to the traditional approach based on the balance of linear momentum, the use of Lagrange's equations leads to a high-level matrix derivation of the formation equations of motion. The matrix form of the nonlinear motion equations is then linearized about a bound Keplerian reference orbit. Next, it is demonstrated that under the assumption of a circular reference orbit, the linearized equations of motion reduce to the well-known Hill-Clohessy-Wiltshire equations. The resulting linear and nonlinear dynamic equations lead to maximal physical insight into the structure of formation dynamics, and are ideally suited for use in the design and validation of formation guidance and control laws.

  14. Low Earth orbit communications satellite

    NASA Technical Reports Server (NTRS)

    Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

    1992-01-01

    A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

  15. Best Mitigation Paths To Effectively Reduce Earth's Orbital Debris

    NASA Technical Reports Server (NTRS)

    Wiegman, Bruce M.

    2009-01-01

    This slide presentation reviews some ways to reduce the problem posed by debris in orbit around the Earth. It reviews the orbital debris environment, the near-term needs to minimize the Kessler syndrome, also known as collisional cascading, a survey of active orbital debris mitigation strategies, the best paths to actively remove orbital debris, and technologies that are required for active debris mitigation.

  16. Distributed earth model/orbiter simulation

    NASA Technical Reports Server (NTRS)

    Geisler, Erik; Mcclanahan, Scott; Smith, Gary

    1989-01-01

    Distributed Earth Model/Orbiter Simulation (DEMOS) is a network based application developed for the UNIX environment that visually monitors or simulates the Earth and any number of orbiting vehicles. Its purpose is to provide Mission Control Center (MCC) flight controllers with a visually accurate three dimensional (3D) model of the Earth, Sun, Moon and orbiters, driven by real time or simulated data. The project incorporates a graphical user interface, 3D modelling employing state-of-the art hardware, and simulation of orbital mechanics in a networked/distributed environment. The user interface is based on the X Window System and the X Ray toolbox. The 3D modelling utilizes the Programmer's Hierarchical Interactive Graphics System (PHIGS) standard and Raster Technologies hardware for rendering/display performance. The simulation of orbiting vehicles uses two methods of vector propagation implemented with standard UNIX/C for portability. Each part is a distinct process that can run on separate nodes of a network, exploiting each node's unique hardware capabilities. The client/server communication architecture of the application can be reused for a variety of distributed applications.

  17. Low-Earth-Orbit and Geosynchronous-Earth-Orbit Testing of 80 Ah Batteries under Real-time Profiles

    NASA Technical Reports Server (NTRS)

    Staniewicz, Robert J.; Willson, John; Briscoe, J. Douglas; Rao, Gopalakrishna M.

    2004-01-01

    This viewgraph presentation gives an update on test results from two 16 cell batteries, one in a simulated Low Earth Orbit (LEO) environment and the other in simulated Geosynchronous Earth Orbit (GEO) environment. The tests measured how voltage and capacity are affected over time by thermal cycling.

  18. The low earth orbit radiation environment and its evolution from measurements using the CREAM and CREDO experiments

    SciTech Connect

    Dyer, C.S.; Sims, A.J.; Truscott, P.R. . Space and Communications Dept.); Farren, J. . Harwell Instruments); Underwood, C. . Surrey Satellite Technology)

    1993-12-01

    Data obtained from Cosmic Radiation Environment Monitors carried on Shuttle missions during 1991/92, as well as on the polar orbiting microsatellite UOSAT-3 since April 1990, show the long term trends in the cosmic-ray and trapped proton environments responsible for single event phenomena. Cosmic-ray fluxes have increased by a factor of two since June 1991, while the solar flare event of Much 1991 created an additional region of trapped radiation which intersects high inclination Shuttle and polar orbits and, although decaying, was still present in December 1992. Deployment at a variety of shielding depths on Shuttle enables the influence of shielding to be explored and shows the influence of secondaries.

  19. Orbital Analysis for Near-Earth Objects

    NASA Technical Reports Server (NTRS)

    Yeomans, D. K.; Chodas, P. W.

    1995-01-01

    For recently discovered Near-Earth Objects (NEO) two body computations can be used to determine the minimum distance between the object's orbit and that of the Earth. Determinations can then be made for potential near-term threats to the Earth. This preliminary orbit analysis must be followed with planetary perturbation computations of the object's future motion to predict actual close Earth approaches.

  20. Micrometeoroid and orbital debris impact inspection of the Hubble Space Telescope Wide Field Planetary Camera 2 radiator and the implications for the near-Earth small particle environment

    NASA Astrophysics Data System (ADS)

    Liou, J.-C.; Anz-Meador, P.; Opiela, J.; Christiansen, E.; Cowardin, H.; Davidson, W.; Ed-Wards, D.; Hedman, T.; Herrin, J.; Hyde, J.; Juarez, Q.; Lear, D.; McNamara, K.; Moser, D.; Ross, D.; Stansbery, E.

    The STS-125 Atlantis astronauts retrieved the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) during a very successful servicing mission to the HST in May 2009. The radiator attached to WFPC2 has dimensions of 2.2 m by 0.8 m. Its outermost layer is a 4-mm thick aluminum plate covered with a white thermal control coating. This radiator had been exposed to space since the deployment of WFPC2 in 1993. Due to its large surface area and long exposure time, the radiator serves as a unique witness plate for the micrometeoroid and orbital debris (MMOD) environment between 560 and 620 km altitude. The NASA Orbital Debris Program Office is leading an effort, with full support from the HST Program at GSFC, NASA Curation Office at JSC, NASA Hypervelocity Impact Technology Facility at JSC, and NASA Meteoroid Environment Office at MSFC, to inspect the exposed radiator surface. The objective is to measure and analyze the MMOD impact damage on the radiator, and then apply the data to validate or improve the near-Earth MMOD environment definition. The initial inspection was completed in September 2009. A total of 685 MMOD impact features (larger than about 0.3 mm) were identified and documented. This paper will provide an overview of the inspection, the analysis of the data, and the initial effort to use the data to model the MMOD environment.

  1. Effects of the low Earth orbit space environment on the surface chemistry of Kapton polyimide film: An XPS study

    NASA Technical Reports Server (NTRS)

    Lee, Myung; Rooney, William; Whiteside, James

    1992-01-01

    Kapton H (DuPont Trademark) polyimide specimens exposed to the low earth (LEO) space environment suffered significant weathering with surface erosions of approximately 8.0 microns. Despite these effects, no significant changes in bulk chemistry were observed. X-ray photoelectron spectroscopy (XPS) was used to determine local changes induced from approximately 25 percent in 1980 vintage ground control specimens to nearly 53 percent in space exposed specimens. The greatest increase was observed for the divalent oxygen moieties, although a slight increase in carbonyl oxygen was also measured. Furthermore, the chemical shifts of all XPS peaks of space-exposed Kapton are shifted to higher energy. This is consistent with a higher oxidation state of the space exposed surface. Finally, space exposed specimens had distinct silicon peaks (2p 100 eV and 2s 149 eV) in their XPS spectra in agreement with widespread reports of silicon contamination throughout the LDEF satellite. These results are discussed in terms of surface reactivity of the polyimide exposed to the LEO environment and the chemical nature of contaminants deposited on flight surfaces due to satellite outgassing.

  2. The Canadian Space Agency, Space Station, Strategic Technologies for Automation and Robotics Program technology development activity in protection of materials from the low Earth orbit space environment

    NASA Technical Reports Server (NTRS)

    Francoeur, J. R.

    1992-01-01

    The Strategic Technologies in Automation and Robotics (STEAR) program is managing a number of development contracts to improve the protection of spacecraft materials from the Low Earth Orbit (LEO) space environment. The project is structured in two phases over a 3 to 4 year period with a budget of 3 to 4 million dollars. Phase 1 is designed to demonstrate the technical feasibility and commercial potential of a coating/substrate system and its associated application process. The objective is to demonstrate a prototype fabrication capability using a full scale component of a commercially viable process for the protection of materials and surface finishes from the LEO space environment, and to demonstrate compliance with a set of performance requirements. Only phase 1 will be discussed in this paper.

  3. Cycler orbit between Earth and Mars

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  4. Spacewire on Earth orbiting scatterometers

    NASA Technical Reports Server (NTRS)

    Bachmann, Alex; Lang, Minh; Lux, James; Steffke, Richard

    2002-01-01

    The need for a high speed, reliable and easy to implement communication link has led to the development of a space flight oriented version of IEEE 1355 called SpaceWire. SpaceWire is based on high-speed (200 Mbps) serial point-to-point links using Low Voltage Differential Signaling (LVDS). SpaceWIre has provisions for routing messages between a large network of processors, using wormhole routing for low overhead and latency. {additionally, there are available space qualified hybrids, which provide the Link layer to the user's bus}. A test bed of multiple digital signal processor breadboards, demonstrating the ability to meet signal processing requirements for an orbiting scatterometer has been implemented using three Astrium MCM-DSPs, each breadboard consists of a Multi Chip Module (MCM) that combines a space qualified Digital Signal Processor and peripherals, including IEEE-1355 links. With the addition of appropriate physical layer interfaces and software on the DSP, the SpaceWire link is used to communicate between processors on the test bed, e.g. sending timing references, commands, status, and science data among the processors. Results are presented on development issues surrounding the use of SpaceWire in this environment, from physical layer implementation (cables, connectors, LVDS drivers) to diagnostic tools, driver firmware, and development methodology. The tools, methods, and hardware, software challenges and preliminary performance are investigated and discussed.

  5. Orbital debris and near-Earth environmental management: A chronology

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  6. How to Orbit the Earth.

    ERIC Educational Resources Information Center

    Quimby, Donald J.

    1984-01-01

    Discusses the geometry, algebra, and logic involved in the solution of a "Mindbenders" problem in "Discover" magazine and applies it to calculations of satellite orbital velocity. Extends the solution of this probe to other applications of falling objects. (JM)

  7. Detection of ocean chlorophyll from earth orbit

    NASA Technical Reports Server (NTRS)

    Duntley, S. Q.

    1972-01-01

    Calculations were made of the magnitude of the optical signature of ocean chlorophyll available to any remote sensor in earth orbit. It was desired to ascertain whether commercially significant concentrations of chlorophyll-A pigments in the ocean would produce a sufficient optical signal at orbital altitudes to operate optical remote sensors, such as those planned for the earth observatory satellite, on clear and hazy days. It was also desired to explore the effect of solar altitude on these optical signals. The best orientation was desired for the field of view for a remote sensor in orbit in order to optimize its ability to detect ocean chlorophyll.

  8. Earth orbiting technologies for understanding global change

    NASA Technical Reports Server (NTRS)

    Harris, Leonard A.; Johnston, Gordon I.; Hudson, Wayne R.; Couch, Lana M.

    1989-01-01

    This paper considers the technology requirements needed to support the Mission to Planet Earth concept, which will consist of several sun synchronous polar platforms; a series of low-earth orbit equatorial missions, such as Space Shuttle payloads, Space-Station-attached payloads, and the Explorer-class Earth Probes; and five geostationary platforms. In particular, the technology requirements in the areas of space-based observation, data/information, and spacecraft operation are examined.

  9. Low-earth-orbit effects on strength of glasses

    NASA Technical Reports Server (NTRS)

    Wiedlocher, David E.; Tucker, Dennis S.; Nichols, Ron; Kinser, Donald L.

    1992-01-01

    The effects of a 5.8-y exposure to low-earth-orbit environment upon the mechanical properties of five commercial glasses and a low-expansion-coefficient glass-ceramic have been examined. The radiation components of the earth-orbit environment did not degrade the mechanical strength of the samples examined within the limits of experimental error. Statistical problems arising from the low frequency of micrometeorite or space debris impacts upon the samples precluded statistically valid measurement of impacted sample strengths. Upper bounds for the magnitude of the impact event damage upon the strengths for impacted samples have been determined.

  10. Orbit Determination System for Low Earth Orbit Satellites

    NASA Technical Reports Server (NTRS)

    Elisha, Yossi; Shyldkrot, Haim; Hankin, Maxim

    2007-01-01

    The IAI/MBT Precise Orbit Determination system for Low Earth Orbit satellites is presented. The system is based on GPS pesudorange and carrier phase measurements and implements the Reduced Dynamics method. The GPS measurements model, the dynamic model, and the least squares orbit determination are discussed. Results are shown for data from the CHAMP satellite and for simulated data from the ROKAR GPS receiver. In both cases the one sigma 3D position and velocity accuracy is about 0.2 m and 0.5 mm/sec respectively.

  11. Observations of Human-Made Debris in Earth Orbit

    NASA Technical Reports Server (NTRS)

    Cowardia, Heather

    2011-01-01

    Orbital debris is defined as any human-made object in orbit about the Earth that no longer serves a useful purpose. Beginning in 1957 with the launch of Sputnik 1, there have been more than 4,700 launches, with each launch increasing the potential for impacts from orbital debris. Almost 55 years later there are over 16,000 catalogued objects in orbit over 10 cm in size. Agencies world-wide have realized this is a growing issue for all users of the space environment. To address the orbital debris issue, the Inter-Agency Space Debris Coordination Committee (IADC) was established to collaborate on monitoring, characterizing, and modeling orbital debris, as well as formulating policies and procedures to help control the risk of collisions and population growth. One area of fundamental interest is measurements of the space debris environment. NASA has been utilizing radar and optical measurements to survey the different orbital regimes of space debris for over 25 years, as well as using returned surfaces to aid in determining the flux and size of debris that are too small to detect with ground-based sensors. This paper will concentrate on the optical techniques used by NASA to observe the space debris environment, specifically in the Geosynchronous earth Orbit (GEO) region where radar capability is severely limited.

  12. Electric Propulsion for Low Earth Orbit Constellations

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Sankovic, John M.

    1998-01-01

    Hall effect electric propulsion was evaluated for orbit insertion, satellite repositioning, orbit maintenance and de-orbit applications for a sample low earth orbit satellite constellation. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion, the Hall thruster system can add additional spacecraft per launch using planned payload power levels. One satellite can be added to the assumed four satellite baseline chemical launch without additional mission times. Two or three satellites may be added by providing part of the orbit insertion with the Hall system. In these cases orbit insertion times were found to be 35 and 62 days. Depending, on the electric propulsion scenario, the resulting launch vehicle savings is nearly two, three or four Delta 7920 launch vehicles out of the chemical baseline scenario's eight Delta 7920 launch vehicles.

  13. Orbit Design of Earth-Observation Satellite

    NASA Astrophysics Data System (ADS)

    Owis, Ashraf

    The purpose of this study is to design a reliable orbit for a medium-resolution scientific satellite to observe Earth for developmental issues such as water resources, agricultural, and industrial. To meet this objective this study firstly, defines the mission, secondly, determines mission constraints, thirdly, design the attitude and orbit control system. As for the observation requirements, and the revisit time are provided as a function of the orbital parameters. Initial orbital parameters are obtained by optimal analysis between observation characteristics and attitude and orbit maintenance costs. Long term station-keeping strategies will be provided for the proposed solutions. Impulsive control will be investigated to provide a reliable and affordable attitude and orbit control system.

  14. Earth orbital variations and vertebrate bioevolution

    NASA Technical Reports Server (NTRS)

    Mclean, Dewey M.

    1988-01-01

    Cause of the Pleistocene-Holocene transition mammalian extinctions at the end of the last age is the subject of debate between those advocating human predation and climate change. Identification of an ambient air temperature (AAT)-uterine blood flow (UBF) coupling phenomenon supports climate change as a factor in the extinctions, and couples the extinctions to earth orbital variations that drive ice age climatology. The AAT-UBF phenomenon couples mammalian bioevolution directly to climate change via effects of environmental heat upon blood flow to the female uterus and damage to developing embryos. Extinctions were in progress during climatic warming before the Younger Dryas event, and after, at times when the AAT-UBF couple would have been operative; however, impact of a sudden short-term cooling on mammals in the process of adapting to smaller size and relatively larger S/V would have been severe. Variations in earth's orbit, and orbital forcing of atmospheric CO2 concentrations, were causes of the succession of Pleistocene ice ages. Coincidence of mammalian extinctions with terminations of the more intense cold stages links mammalian bioevolution to variations in earth's orbit. Earth orbital variations are a driving source of vertebrate bioevolution.

  15. Mitigating Climate Change with Earth Orbital Sunshades

    NASA Technical Reports Server (NTRS)

    Coverstone, Victoria; Johnson, Les

    2015-01-01

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

  16. Spatial Analysis of Galactic Cosmic Ray Particles in Low Earth Orbit/Near Equator Orbit Using SPENVIS

    NASA Astrophysics Data System (ADS)

    Suparta, W.; Zulkeple, S. K.

    2014-04-01

    The space environment has grown intensively harmful to spacecraft and astronauts. Galactic cosmic rays (GCRs) are one of the radiation sources that composed of high energetic particles originated from space and capable of damaging electronic systems through single event upset (SEU) process. In this paper, we analyzed GCR fluxes at different altitudes by using Space Environment Information System (SPENVIS) software and the results are compared to determine their intensities with respect to distance in the Earth's orbit. The altitudes are set at low earth orbit (400 km and 685 km), medium earth orbit (19,100 km and 20,200 km) and high earth orbit (35,793 km and 1,000,000 km). Then, within Low Earth Orbit (LEO) near the equator (NEqO), we used altitude of 685 km to compare GCRs with the intensities of solar particles and trapped particles in the radiation belt to determine the significance of GCRs in the orbit itself.

  17. Airbreathing Acceleration Toward Earth Orbit

    SciTech Connect

    Whitehead, J C

    2007-05-09

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

  18. Earth Orbital Science, Space in the Seventies.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is part of the "Space in the Seventies" series and reviews the National Aeronautics and Space Administration's (NASA) earth orbital scientific research programs in progress and those to be pursued in the coming decade. Research in space physics is described in Part One in these areas: interplanetary monitoring platforms, small…

  19. Earth orbital teleoperator systems evaluation

    NASA Technical Reports Server (NTRS)

    Shields, N. L., Jr.; Slaughter, P. H.; Brye, R. G.; Henderson, D. E.

    1979-01-01

    The mechanical extension of the human operator to remote and specialized environments poses a series of complex operational questions. A technical and scientific team was organized to investigate these questions through conducting specific laboratory and analytical studies. The intent of the studies was to determine the human operator requirements for remotely manned systems and to determine the particular effects that various system parameters have on human operator performance. In so doing, certain design criteria based on empirically derived data concerning the ultimate control system, the human operator, were added to the Teleoperator Development Program.

  20. The O/OREOS Mission - Astrobiology in Low Earth Orbit. [Astrobiology in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Ehrenfreund, P.; Ricco, A. J.; Squires, D.; Kitts, C.; Agasid, E.; Bramall, N.; Bryson, K.; Chittenden, J.; Conley, C.; Cook, A.; Mancinelli, R.; Mattioda, A.; Nicholson, W.; Quinn, R.; Santos, O.; Tahu, G.; Voytek, M.; Beasley, C.; Bica, L.; Diaz-Aguado, M.; Friedericks, C.; Henschke, M.; Mai, N.; McIntyre, M.; Yost, B.

    2014-01-01

    The O/OREOS (Organism/Organic Exposure to Orbital Stresses) nanosatellite is the first science demonstration spacecraft and flight mission of the NASA Astrobiology Small- Payloads Program (ASP). O/OREOS was launched successfully on November 19, 2010, to a high-inclination (72 deg), 650-km Earth orbit aboard a US Air Force Minotaur IV rocket from Kodiak, Alaska. O/OREOS consists of 3 conjoined cubesat (each 1000 cu cm) modules: (i) a control bus; (ii) the Space Environment Survivability of Living Organisms (SESLO) experiment; and (iii) the Space Environment Viability of Organics (SEVO) experiment. Among the innovative aspects of the O/OREOS mission are a real-time analysis of the photostability of organics and biomarkers and the collection of data on the survival and metabolic activity for microorganisms at 3 times during the 6-month mission. We report on the spacecraft characteristics, payload capabilities, and present operational phase and flight data from the O/OREOS mission. The science and technology rationale of O/OREOS supports NASA0s scientific exploration program by investigating the local space environment as well as space biology relevant to Moon and Mars missions. It also serves as a precursor for experiments on small satellites, the International Space Station (ISS), future free-flyers and lunar surface exposure facilities.

  1. Unique Non-Keplerian Orbit Vantage Locations for Sun-Earth Connection and Earth Science Vision Roadmaps

    NASA Technical Reports Server (NTRS)

    Folta, David; Young, Corissa; Ross, Adam

    2001-01-01

    The purpose of this investigation is to determine the feasibility of attaining and maintaining unique non-Keplerian orbit vantage locations in the Earth/Moon environment in order to obtain continuous scientific measurements. The principal difficulty associated with obtaining continuous measurements is the temporal nature of astrodynamics, i.e., classical orbits. This investigation demonstrates advanced trajectory designs to meet demanding science requirements which cannot be met following traditional orbital mechanic logic. Examples of continuous observer missions addressed include Earth pole-sitters and unique vertical libration orbits that address Sun-Earth Connection and Earth Science Vision roadmaps.

  2. Retrieval of RTG'S in earth orbit

    SciTech Connect

    Raab, B.; Frieder, M.A.; Skrabek, A.

    1982-08-01

    Since 1961, some ten Radioisotope Thermoelectric Generators (RTG's) have been placed into a variety of spacecraft which are now in earth orbit. All of these spacecraft are in orbits with lifetimes in excess of 100 years and pose no risk. However, since most of these spacecraft are no longer being actively used, these may be subject to an active removal program to reduce the population of objects in space. Therefore, a study was undertaken to evaluate the feasibility of retrieving or disposing of spacecraft with RTGs on board. Intervention scenarios are developed and an orbital rendezvous vehicle is conceptualized. The costs of RTG retrieval are derived and compared to the costs of RTG disposal, i.e., boost to a higher, multi-millenium-lifetime orbit, and are found to be not significantly different.

  3. Nickel hydrogen low Earth orbit life testing

    NASA Technical Reports Server (NTRS)

    Badcock, C. C.; Haag, R. L.

    1986-01-01

    A program to demonstrate the long term reliability of NiH2 cells in low Earth orbits (LEO) and support use in mid-altitude orbits (MAO) was initiated. Both 3.5 and 4.5 inch diameter nickel hydrogen cells are included in the test plan. Cells from all U.S. vendors are to be tested. The tests will be performed at -5 and 10 C at 40 and 60% DOD for LEO orbit and 10 C and 80% DOD for MAO orbit simulations. The goals of the testing are 20,000 cycles at 60% DOD and 30,000 cycles at 40% DOD. Cells are presently undergoing acceptance and characterization testing at Naval Weapons Systems Center, Crane.

  4. Nickel hydrogen low Earth orbit life testing

    NASA Astrophysics Data System (ADS)

    Badcock, C. C.; Haag, R. L.

    1986-09-01

    A program to demonstrate the long term reliability of NiH2 cells in low Earth orbits (LEO) and support use in mid-altitude orbits (MAO) was initiated. Both 3.5 and 4.5 inch diameter nickel hydrogen cells are included in the test plan. Cells from all U.S. vendors are to be tested. The tests will be performed at -5 and 10 C at 40 and 60% DOD for LEO orbit and 10 C and 80% DOD for MAO orbit simulations. The goals of the testing are 20,000 cycles at 60% DOD and 30,000 cycles at 40% DOD. Cells are presently undergoing acceptance and characterization testing at Naval Weapons Systems Center, Crane.

  5. Earth orbital operations supporting manned interplanetary missions

    NASA Astrophysics Data System (ADS)

    Sherwood, Brent; Buddington, Patricia A.; Whittaker, William L.

    The orbital operations required to accumulate, assemble, test, verify, maintain, and launch complex manned space systems on interplanetary missions from earth orbit are as vital as the flight hardware itself. Vast numbers of orbital crew are neither necessary nor desirable for accomplishing the required tasks. A suite of robotic techniques under human supervisory control, relying on sensors, software and manipulators either currently emergent or already applied in terrestrial settings, can make the job tractable. The mission vehicle becomes largely self-assembling, using its own rigid aerobrake as a work platform. The Space Station, having been used as a laboratory testbed and to house an assembly crew of four, is not dominated by the process. A feasible development schedule, if begun soon, could emplace orbital support technologies for exploration missions in time for a 2004 first interplanetary launch.

  6. MAPPING EARTH ANALOGS FROM PHOTOMETRIC VARIABILITY: SPIN-ORBIT TOMOGRAPHY FOR PLANETS IN INCLINED ORBITS

    SciTech Connect

    Fujii, Yuka; Kawahara, Hajime

    2012-08-20

    Aiming at obtaining detailed information on the surface environment of Earth analogs, Kawahara and Fujii proposed an inversion technique of annual scattered light curves named spin-orbit tomography (SOT), which enables us to sketch a two-dimensional albedo map from annual variation of the disk-integrated scattered light, and demonstrated the method with a planet in a face-on orbit. We extend it to be applicable to general geometric configurations, including low-obliquity planets like the Earth in inclined orbits. We simulate light curves of the Earth in an inclined orbit in three photometric bands (0.4-0.5 {mu}m, 0.6-0.7 {mu}m, and 0.8-0.9 {mu}m) and show that the distribution of clouds, snow, and continents is retrieved with the aid of the SOT. We also demonstrate the SOT by applying it to an upright Earth, a tidally locked Earth, and Earth analogs with ancient continental configurations. The inversion is model independent in the sense that we do not assume specific albedo models when mapping the surface, and hence applicable in principle to any kind of inhomogeneity. This method can potentially serve as a unique tool to investigate the exohabitats/exoclimes of Earth analogs.

  7. Tracking and orbit determination of near earth orbiting satellites using earth synchronous relay satellites

    NASA Technical Reports Server (NTRS)

    Bryant, W. C., Jr.; Goad, C. C.

    1973-01-01

    A Tracking Data Relay Satellite System (TDRSS) made up of two earth synchronous data relay satellites is proposed for the late 1970s to aid in the tracking, or take the place of ground tracking, or near-earth orbiters. Theoretical error analysis studies were conducted to evaluate the TDRSS concept of tracking user satellites. All major factors affecting orbit determination accuracy were considered in the analysis, including tracking system and dynamic modeling errors.

  8. Near Earth asteroid orbit perturbation and fragmentation

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Harris, Alan W.

    1992-01-01

    Collisions by near earth asteroids or the nuclei of comets pose varying levels of threat to man. A relatively small object, approximately 100 meter diameter, which might be found on an impact trajectory with a populated region of the Earth, could potentially be diverted from an Earth impacting trajectory by mass driver rocket systems. For larger bodies, such systems would appear to be beyond current technology. For any size object, nuclear explosions appear to be more efficient, using either the prompt blow-off from neutron radiation, the impulse from ejecta of near-surface explosion for deflection, or as a fragmenting charge. Practical deflections of bodies with diameters of 0.1, 1, and 10 km require interception, years to decades prior to earth encounter, with explosions a few kilotons, megatons, or gigatons, respectively, of equivalent TNT energy to achieve orbital velocity changes or destruction to a level where fragments are dispersed to harmless spatial densities.

  9. Near Earth asteroid orbit perturbation and fragmentation

    NASA Astrophysics Data System (ADS)

    Ahrens, Thomas J.; Harris, Alan W.

    1992-03-01

    Collisions by near earth asteroids or the nuclei of comets pose varying levels of threat to man. A relatively small object, approximately 100 meter diameter, which might be found on an impact trajectory with a populated region of the Earth, could potentially be diverted from an Earth impacting trajectory by mass driver rocket systems. For larger bodies, such systems would appear to be beyond current technology. For any size object, nuclear explosions appear to be more efficient, using either the prompt blow-off from neutron radiation, the impulse from ejecta of near-surface explosion for deflection, or as a fragmenting charge. Practical deflections of bodies with diameters of 0.1, 1, and 10 km require interception, years to decades prior to earth encounter, with explosions a few kilotons, megatons, or gigatons, respectively, of equivalent TNT energy to achieve orbital velocity changes or destruction to a level where fragments are dispersed to harmless spatial densities.

  10. Earth Albedo and the orbit of LAGEOS

    NASA Technical Reports Server (NTRS)

    Rubincam, D. P.; Weiss, N. R.

    1985-01-01

    The long-period perturbations in the orbit of the Lageos satellite due to the Earth's albedo have been found using a new analytical formalism. The Earth is assumed to be a sphere whose surface diffusely reflects sunlight according to Lambert's law. Specular reflection is not considered. The formalism is based on spherical harmonics; it produces equations which hold regardless of whether the terminator is seen by the satellite or not. Specializing to the case of a realistic zonal albedo shows that Lageos' orbital semimajor axis changes periodically by only the a few millimeters and the eccentricity by one part in 100,000. The longitude of the node increases secularly. The effect considered here can explain neither the secular decay of 1.1 mm/day in the semimajor axis nor the observed along-track variations in acceleration of order 2 x 10 to the minus 12 power/sq ms.

  11. Extravehicular activity at geosynchronous earth orbit

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  12. Cargo launch vehicles to low earth orbit

    NASA Technical Reports Server (NTRS)

    Austin, Robert E.

    1990-01-01

    There are two primary space transportation capabilities required to support both base programs and expanded mission requirements: earth-to-orbit (ETO) transportation systems and space transfer vehicle systems. Existing and new ETO vehicles required to support mission requirements, and planned robotic missions, along with currently planned ETO vehicles are provided. Lunar outposts, Mars' outposts, base and expanded model, ETO vehicles, advanced avionics technologies, expert systems, network architecture and operations systems, and technology transfer are discussed.

  13. Low-Earth orbit satellite servicing economics

    NASA Technical Reports Server (NTRS)

    Davis, R. F.; Cepollina, F. J.

    1982-01-01

    Servicing economics of low Earth orbit satellites were studied. The following topics are examined: the economic importance of the repair missions; comparison of mission cost as opposed to satellite modulation transfer functions over a 10 year period; the effect of satellite flight rate change due to changes in satellite failure rate; estimated satellite cost reduction with shuttle operation projects from the 1960's to the 1970's; design objectives of the multimission modular spacecraft; and the economic importance of the repair mission.

  14. Earth's magnetic environment

    SciTech Connect

    Lanzerotti, L.J.; Uberoi, C.

    1988-10-01

    The nature of the earth's magnetosphere is outlined. The magnetosphere is illustrated and its regions and features are discussed, including solar wind, bow shock, and the magnetopause. The formation process and characteristics of the magnetotail are presented. The plasmasphere, Van Allen belts, auroras, whistlers, and micropulsations are examined. Effects of the magnetosphere, including problems for communications lines, spacecraft electronics, and communication satellites are considered.

  15. An Investigation of Low Earth Orbit Internal Charging

    NASA Technical Reports Server (NTRS)

    Parker, Linda Neergaard; Minow, Joseph; Willis, Emily

    2014-01-01

    Internal charging is not generally considered a threat in low Earth orbit due to the relatively short exposure times and low flux of electrons with energies of a few MeV encountered in typical orbits. There are configurations, however, where insulators and ungrounded conductors used on the outside of a spacecraft hull may charge when exposed to much lower energy electrons of some 100's keV in a process that is better characterized as internal charging than surface charging. We investigate the conditions required for this internal charging process to occur in low Earth orbit using a one-dimensional charging model and evaluate the environments for which the process may be a threat to spacecraft.

  16. Materials resistance to low earth orbit environmental effects

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  17. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2016-01-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4}-10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  18. Nickel hydrogen low earth orbit life testing

    NASA Astrophysics Data System (ADS)

    Badcock, Charles C.; Haag, R. L.

    1988-02-01

    A program to demonstrate the long-term reliability of nickel hydrogen (NiH2) cells in low earth orbit (LEO) and support use in mid-altitude orbit (MAO) has been initiated. Both 3.5 and 4.5 in. diameter NiH2 cells are included in the test plan. Cells from all U.S. vendors are to be tested. The tests will be performed at -5 and 10 C at 40 and 60 percent depth of discharge (DOD) for LEO orbit and 10 C and 80 percent DOD for MAO orbit simulations. The goals of the testing are 20,000 cycles at 60 percent DOD and 30,000 cycles at 40 percent DOD. Cells are presently undergoing acceptance and characterization testing at Naval Weapons Support Center (NWSC), Crane, Indiana. Funding has been provided by the Air Force Space Technology Center (AFSTC) and two AF System Program Offices (SPO's) to initiate the testing, but additional funding must be acquired to complete the purchase of cells and to assure completion of the testing.

  19. Earth-orbiting resonant-mass gravitational wave detectors

    NASA Technical Reports Server (NTRS)

    Paik, Ho Jung

    1989-01-01

    Earth-based gravitational wave detectors suffer from the need to support the large antenna masses against the earth's gravity without transmitting a significant amount of seismic noise. Passive vibration isolation is difficult to achieve below 1 Hz on the earth. Vibration-free space environment thus gives an opportunity to extend the frequency window of gravitational wave detection to ultralow frequencies. The weightless condition of a space laboratory also enables construction of a highly symmetric multimode antenna which is capable of resolving the direction of the source and the polarization of the incoming wave without resorting to multiantenna coincidence. Two types of earth-orbiting resonant-mass gravitational wave detectors are considered. One is a skyhook gravitational wave detector, proposed by Braginsky and Thorne (1985). The other is a spherical detector, proposed by Forward (1971) and analyzed by Wagoner and Paik (1976).

  20. Earth orbit navigation study. Volume 2: System evaluation

    NASA Technical Reports Server (NTRS)

    1972-01-01

    An overall systems evaluation was made of five candidate navigation systems in support of earth orbit missions. The five systems were horizon sensor system, unkown landmark tracking system, ground transponder system, manned space flight network, and tracking and data relay satellite system. Two reference missions were chosen: a low earth orbit mission and a transfer trajectory mission from low earth orbit to geosynchronous orbit. The specific areas addressed in the evaluation were performance, multifunction utilization, system mechanization, and cost.

  1. Cauchy Drag Estimation For Low Earth Orbiters

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell; Mashiku, Alinda K.

    2015-01-01

    Recent work on minimum variances estimators based on Cauchy distributions appear relevant to orbital drag estimation. Samples form Cauchy distributions which are part of a class of heavy-tailed distributions, are characterized by long stretches of fairly small variation, punctuated by large variations that are many times larger than could be expected from a Gaussian. Such behavior can occur when solar storms perturb the atmosphere. In this context, the present work describes an embedding of the scalar Idan-Speyer Cauchy Estimator to estimate density corrections, within an Extended Kalman Filter that estimates the state of a low Earth orbiter. In contrast to the baseline Kalman approach, the larger formal errors of the present approach fully and conservatively bound the predictive error distribution, even in the face of unanticipated density disturbances of hundreds of percent.

  2. Earth-to-Orbit Rocket Propulsion

    NASA Technical Reports Server (NTRS)

    Beaurain, Andre; Souchier, Alain; Moravie, Michel; Sackheim, Robert L.; Cikanek, Harry A., III

    2003-01-01

    The Earth-to-orbit (ETO) phase of access to space is and always will be the first and most critical phase of all space missions. This first phase of all space missions has unique characteristics that have driven space launcher propulsion requirements for more than half a century. For example, the need to overcome the force of the Earth s gravity in combination with high levels of atmospheric drag to achieve the initial orbital velocity; i.e., Earth parking orbit or =9 km/s, will always require high thrust- to-weight (TN) propulsion systems. These are necessary with a T/W ratio greater than one during the ascent phase. The only type of propulsion system that can achieve these high T/W ratios are those that convert thermal energy to kinetic energy. There are only two basic sources of onboard thermal energy: chemical combustion-based systems or nuclear thermal-based systems (fission, fusion, or antimatter). The likelihood of advanced open-cycle, nuclear thermal propulsion being developed for flight readiness or becoming environmentally acceptable during the next century is extremely low. This realization establishes that chemical propulsion for ET0 launchers will be the technology of choice for at least the next century, just as it has been for the last half century of rocket flight into space. The world s space transportation propulsion requirements have evolved through several phases over the history of the space program, as has been necessitated by missions and systems development, technological capabilities available, and the growth and evolution of the utilization of space for economic, security, and science benefit. Current projections for the continuing evolution of requirements and concepts may show how future space transportation system needs could be addressed. The evolution and projections will be described in detail in this manuscript.

  3. Earth Parking Orbit and Translunar Injection

    NASA Technical Reports Server (NTRS)

    Interbartolo, Michael

    2009-01-01

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

  4. Introduction to simulation of upper atmosphere oxygen satellite exposed to atomic oxygen in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Peplinski, D. R.; Arnold, G. S.; Borson, E. N.

    1984-01-01

    A brief review of atmospheric composition in low Earth orbit is presented. The flux of ambient atomic oxygen incident on a surface orbiting in this environment is described. Estimates are presented of the fluence of atomic oxygen to which satellite surfaces in various orbits are exposed.

  5. Ranking upper stages in low Earth orbit for active removal

    NASA Astrophysics Data System (ADS)

    Anselmo, L.; Pardini, C.

    2016-05-01

    This paper addresses the problem of ranking the upper stages in orbit in order to evaluate their potential detrimental effects on the debris environment over the long-term, and the relative advantage of having them actively de-orbited. To do so, a new ranking scheme is introduced, applicable to any object in low Earth orbit (LEO) and able to prioritize the target objects potentially most critical for the future preservation of the LEO protected region. Applying the proposed approach, it was found, for instance, that the 22 most massive upper stages abandoned in LEO, at the beginning of 2015, are on the whole equivalent to several hundred average intact objects in sun-synchronous orbit, regarding their latent detrimental effects on the debris environment over the next 200 years. Most of them could therefore be the top priority targets of any worldwide coordinated effort for active removal and the prevention of new collisional debris. The ranking scheme was also applied to other main models of rocket bodies currently in orbit, trying to identify the combinations of orbital elements and upper stage types requiring particular attention.

  6. Reentry analysis for low Earth orbiting spacecraft

    NASA Astrophysics Data System (ADS)

    Newman, Lauri Kraft; Folta, David C.; Ross, Brian P.; Bouslog, Stanley A.

    As a result of recent National Aeronautics and Space Administration (NASA) Management Instruction (NMI), NASA spacecraft programs must limit orbital debris by design and/or by operational procedures. To fulfill this requirement, spacecraft may be required to be removed from their operational orbit after mission completion. Spacecraft disposal by atmospheric reentry is a means to accomplish this task. To assess the risk to man, an analysis must be done to determine which parts of the spacecraft are likely to survive a reentry of the Earth's atmosphere and where those parts will land. These issues are currently being examined for the Earth Observing System (EOS-AM1). The Johnson Space Center (JSC) Aeroscience Branch, supported by the Lockheed Engineering and Sciences Co., has developed a tool which permits the analysis of the thermal effects of reentry on individual spacecraft components to determine which components are expected to survive reentry. This paper presents an examination of the burnup and reentry of EOS-AM1 and describes a method for other spacecraft to use in analyzing similar reentry issues.

  7. Low Earth Orbit satellite traffic simulator

    NASA Technical Reports Server (NTRS)

    Hoelzel, John

    1995-01-01

    This paper describes a significant tool for Low Earth Orbit (LEO) capacity analysis, needed to support marketing, economic, and design analysis, known as a Satellite Traffic Simulator (STS). LEO satellites typically use multiple beams to help achieve the desired communication capacity, but the traffic demand in these beams in usually not uniform. Simulations of dynamic, average, and peak expected demand per beam is a very critical part of the marketing, economic, and design analysis necessary to field a viable LEO system. An STS is described in this paper which can simulate voice, data and FAX traffic carried by LEO satellite beams and Earth Station Gateways. It is applicable world-wide for any LEO satellite constellations operating over any regions. For aeronautical applications to LEO satellites. the anticipates aeronautical traffic (Erlangs for each hour of the day to be simulated) is prepared for geographically defined 'area targets' (each major operational region for the respective aircraft), and used as input to the STS. The STS was designed by Constellations Communications Inc. (CCI) and E-Systems for usage in Brazil in accordance with an ESCA/INPE Statement Of Work, and developed by Analytical Graphics Inc. (AGI) to execute on top of its Satellite Tool Kit (STK) commercial software. The STS simulates constellations of LEO satellite orbits, with input of traffic intensity (Erlangs) for each hour of the day generated from area targets (such as Brazilian States). accumulated in custom LEO satellite beams, and then accumulated in Earth Station Gateways. The STS is a very general simulator which can accommodate: many forms of orbital element and Walker Constellation input; simple beams or any user defined custom beams; and any location of Gateways. The paper describes some of these features, including Manual Mode dynamic graphical display of communication links, to illustrate which Gateway links are accessible and which links are not, at each 'step' of the

  8. A low Earth orbit molecular beam space simulation facility

    NASA Technical Reports Server (NTRS)

    Cross, J. B.

    1984-01-01

    A brief synopsis of the low Earth orbit (LEO) satellite environment is presented including neutral and ionic species. Two ground based atomic and molecular beam instruments are described which are capable of simulating the interaction of spacecraft surfaces with the LEO environment and detecting the results of these interactions. The first detects mass spectrometrically low level fluxes of reactively and nonreactively surface scattered species as a function of scattering angle and velocity while the second ultrahigh velocity (UHV) molecular beam, laser induced fluorescence apparatus is capable of measuring chemiluminescence produced by either gas phase or gas-surface interactions. A number of proposed experiments are described.

  9. Supportability for Beyond Low Earth Orbit Missions

    NASA Technical Reports Server (NTRS)

    Crillo, William M.; Goodliff, Kandyce E.; Aaseng, Gordon; Stromgren, Chel; Maxwell, Andrew J.

    2011-01-01

    Exploration beyond Low Earth Orbit (LEO) presents many unique challenges that will require changes from current Supportability approaches. Currently, the International Space Station (ISS) is supported and maintained through a series of preplanned resupply flights, on which spare parts, including some large, heavy Orbital Replacement Units (ORUs), are delivered to the ISS. The Space Shuttle system provided for a robust capability to return failed components to Earth for detailed examination and potential repair. Additionally, as components fail and spares are not already on-orbit, there is flexibility in the transportation system to deliver those required replacement parts to ISS on a near term basis. A similar concept of operation will not be feasible for beyond LEO exploration. The mass and volume constraints of the transportation system and long envisioned mission durations could make it difficult to manifest necessary spares. The supply of on-demand spare parts for missions beyond LEO will be very limited or even non-existent. In addition, the remote nature of the mission, the design of the spacecraft, and the limitations on crew capabilities will all make it more difficult to maintain the spacecraft. Alternate concepts of operation must be explored in which required spare parts, materials, and tools are made available to make repairs; the locations of the failures are accessible; and the information needed to conduct repairs is available to the crew. In this paper, ISS heritage information is presented along with a summary of the challenges of beyond LEO missions. A number of Supportability issues are discussed in relation to human exploration beyond LEO. In addition, the impacts of various Supportability strategies will be discussed. Any measure that can be incorporated to reduce risk and improve mission success should be evaluated to understand the advantages and disadvantages of implementing those measures. Finally, an effort to model and evaluate

  10. Radiation Protection Quantities for Near Earth Environments

    NASA Technical Reports Server (NTRS)

    Clowdsley, Martha S.; Wilson, John W.; Kim, Myung-Hee; Anderson, Brooke M.; Nealy, John E.

    2004-01-01

    As humans travel beyond the protection of the Earth's magnetic field and mission durations grow, risk due to radiation exposure will increase and may become the limiting factor for such missions. Here, the dosimetric quantities recommended by the National Council on Radiation Protection and Measurements (NCRP) for the evaluation of health risk due to radiation exposure, effective dose and gray-equivalent to eyes, skin, and blood forming organs (BFO), are calculated for several near Earth environments. These radiation protection quantities are evaluated behind two different shielding materials, aluminum and polyethylene. Since exposure limits for missions beyond low Earth orbit (LEO) have not yet been defined, results are compared to limits recommended by the NCRP for LEO operations.

  11. Workshop on the Earth`s Trapped Particle Environment. Proceedings

    SciTech Connect

    Reeves, G.D.

    1997-01-01

    These proceedings contain the papers presented at the Workshop on the Earth`s Trapped Particle Environment. The meeting was sponsored by the Nonproliferation and International Security Division of Los Alamos National laboratory of the U.S. Department of Energy. The proceedings are divided into four sections: The Outer Zone, The Inner Zone, Composition Studies, and General Contributions. Each section contains a mixture of overview papers, observations, theory, and modeling. The topics discussed included: structure and dynamics of the outer zone; observations from geosynchronous orbit, wave{minus}particle interactions; inner zone electron and proton characteristics; the effects of the magnetic storm on March 24,1991; ion composition measurements provided by spacecrafts; instruments and data sets. There were 31 papers presented and all have been abstracted for the Energy Science and Technology database. (AIP)

  12. Taurus Lightweight Manned Spacecraft Earth orbiting vehicle

    NASA Technical Reports Server (NTRS)

    Bosset, M.

    1991-01-01

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

  13. Taurus Lightweight Manned Spacecraft Earth orbiting vehicle

    NASA Astrophysics Data System (ADS)

    Bosset, M.

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

  14. Taurus lightweight manned spacecraft Earth orbiting vehicle

    NASA Technical Reports Server (NTRS)

    Chase, Kevin A.; Vandersall, Eric J.; Plotkin, Jennifer; Travisano, Jeffrey J.; Loveless, Dennis; Kaczmarek, Michael; White, Anthony G.; Est, Andy; Bulla, Gregory; Henry, Chris

    1991-01-01

    The Taurus Lightweight Manned Spacecraft (LMS) was developed by students of the University of Maryland's Aerospace Engineering course in Space Vehicle Design. That course required students to design an Alternative Manned Spacecraft (AMS) to augment or replace the Space Transportation System and meet the following design requirements: (1) launch on the Taurus Booster being developed by Orbital Sciences Corporation; (2) 99.9 percent assured crew survival rate; (3) technology cutoff data of 1 Jan. 1991; (4) compatibility with current space administration infrastructure; and (5) first flight by May 1995. The Taurus LMS design meets the above requirements and represents an initial step towards larger and more complex spacecraft. The Taurus LMS has a very limited application when compared to the Space Shuttle, but it demonstrates that the U.S. can have a safe, reliable, and low cost space system. The Taurus LMS is a short mission duration spacecraft designed to place one man into low earth orbit (LEO). The driving factor for this design was the low payload carrying capabilities of the Taurus Booster--1300 kg to a 300 km orbit. The Taurus LMS design is divided into six major design sections. The human factors system deals with the problems of life support and spacecraft cooling. The propulsion section contains the abort system, the Orbital Maneuvering System (OMS), the Reaction Control System (RCS), and power generation. The thermal protection systems and spacecraft structure are contained in the structures section. The avionics section includes navigation, attitude determination, data processing, communication systems, and sensors. The mission analysis section was responsible for ground processing and spacecraft astrodynamics. The systems integration section pulled the above sections together into one spacecraft and addressed costing and reliability.

  15. Three Super-Earths Orbiting HD 7924

    NASA Astrophysics Data System (ADS)

    Fulton, Benjamin J.; Weiss, Lauren M.; Sinukoff, Evan; Isaacson, Howard; Howard, Andrew W.; Marcy, Geoffrey W.; Henry, Gregory W.; Holden, Bradford P.; Kibrick, Robert I.

    2015-06-01

    We report the discovery of two super-Earth-mass planets orbiting the nearby K0.5 dwarf HD 7924, which was previously known to host one small planet. The new companions have masses of 7.9 and 6.4 {{M}\\oplus }, and orbital periods of 15.3 and 24.5 days. We perform a joint analysis of high-precision radial velocity data from Keck/HIRES and the new Automated Planet Finder Telescope (APF) to robustly detect three total planets in the system. We refine the ephemeris of the previously known planet using 5 yr of new Keck data and high-cadence observations over the last 1.3 yr with the APF. With this new ephemeris, we show that a previous transit search for the inner-most planet would have covered 70% of the predicted ingress or egress times. Photometric data collected over the last eight years using the Automated Photometric Telescope shows no evidence for transits of any of the planets, which would be detectable if the planets transit and their compositions are hydrogen-dominated. We detect a long-period signal that we interpret as the stellar magnetic activity cycle since it is strongly correlated with the Ca ii H and K activity index. We also detect two additional short-period signals that we attribute to rotationally modulated starspots and a one-month alias. The high-cadence APF data help to distinguish between the true orbital periods and aliases caused by the window function of the Keck data. The planets orbiting HD 7924 are a local example of the compact, multi-planet systems that the Kepler Mission found in great abundance. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time was granted for this project by the University of Hawai‘i, the University of California, and NASA.

  16. Plasma Flowfields Around Low Earth Orbit Objects: Aerodynamics to Underpin Orbit Predictions

    NASA Astrophysics Data System (ADS)

    Capon, Christopher; Boyce, Russell; Brown, Melrose

    2016-07-01

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

  17. Safety in earth orbit study. Volume 1: Technical summary

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A summary of the technical results and conclusions is presented of the hazards analyses of earth orbital operations in conjunction with the space shuttle program. The space shuttle orbiter and a variety of manned and unmanned payloads delivered to orbit by the shuttle are considered. The specific safety areas examined are hazardous payloads, docking, on-orbit survivability, tumbling spacecraft, and escape and rescue.

  18. Earth view: A business guide to orbital remote sensing

    NASA Technical Reports Server (NTRS)

    Bishop, Peter C.

    1990-01-01

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

  19. Single Event Effects Testing For Low Earth Orbit Missions with Neutrons

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  20. Collisional cascading - The limits of population growth in low earth orbit

    NASA Technical Reports Server (NTRS)

    Kessler, Donald J.

    1991-01-01

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

  1. A facility to produce an energetic, ground state atomic oxygen beam for the simulation of the Low-Earth Orbit environment

    NASA Technical Reports Server (NTRS)

    Ketsdever, Andrew D.; Weaver, David P.; Muntz, E. P.

    1994-01-01

    Because of the continuing commitment to activity in low-Earth orbit (LEO), a facility is under development to produce energetic atmospheric species, particularly atomic oxygen, with energies ranging from 5 to 80 eV. This relatively high flux facility incorporates an ion engine to produce the corresponding specie ion which is charge exchanged to produce a neutral atomic beam. Ion fluxes of around 10(exp 15) sec(exp -1) with energies of 20-70 eV have been achieved. A geometrically augmented inertially tethered charge exchanger (GAITCE) was designed to provide a large column depth of charge exchange gas while reducing the gas load to the low pressure portion of the atomic beam facility. This is accomplished using opposed containment jets which act as collisional barriers to the escape of the dense gas region formed between the jets. Leak rate gains to the pumping system on the order of 10 were achieved for moderate jet mass flows. This system provides an attractive means for the charge exchange of atomic ions with a variety of gases to produce energetic atomic beams.

  2. Observatories in earth orbit and beyond

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji (Editor)

    1990-01-01

    The present volume on observations in earth orbit and beyond discusses current and future missions, launch vehicles, the relative merits of various observatories, and long-term future issues. Attention is given to the Granat automatic spacecraft, the prospects of the Hipparcos mission, EUV and FUV astronomy from Voyagers 1 and 2, and the X-ray Timing Explorer. Topics addressed include the SAX mission for X-ray astronomy, the Space Infrared Telescope Facility, the Ulysses mission in the high-latitude heliosphere, and science operations for future space astrophysics missions. Also discussed are science observations with the IUE using the one-gyro mode, new methods of determining spacecraft attitude, cryogenic testing of optics for ISOCAM, and the stellar X-ray polarimeter for the Spectrum-X-Gamma mission.

  3. Investigation of Teflon FEP embrittlement on spacecraft in low earth orbit

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Smith, Daniela C.

    1997-01-01

    Teflon(TM) fluorinated ethylene-propylene (FEP) is used on the exterior of spacecraft surfaces in the low earth orbit environment for thermal control. Silverized or aluminized Teflon(TM) FEP used in the Long Duration Exposure Facility (LDEF) and the Hubble Space Telescope (HST) provided evidence of the low earth orbit environments. Samples from the LDEF and HST were evaluated for solar induced embrittlement and for synergistic effects of solar degradation and atomic oxygen.

  4. Material Density Distribution of Small Debris in Earth Orbit

    NASA Technical Reports Server (NTRS)

    Krisko, P. H.; Xu, Y.-l.; Opiela, J. N.; Hill, N. M.; Matney, M. J.

    2008-01-01

    Earth orbit. The near Earth environment is thus parameterized by debris density percentages within subsections of that environment. This model version is used in the upgraded NASA Orbital Debris Engineering Model (ORDEM).

  5. Post-disposal orbital evolution of satellites and upper stages used by the GPS and GLONASS navigation constellations: The long-term impact on the Medium Earth Orbit environment

    NASA Astrophysics Data System (ADS)

    Pardini, Carmen; Anselmo, Luciano

    2012-08-01

    The long-term evolution and environmental impact in MEO of all the abandoned spacecraft and upper stages associated with the GPS and GLONASS navigation constellations were analyzed. The orbits of the disposed objects, as of 1 May 2011, were propagated for 200 years and snapshots of their evolving distribution were obtained, together with an estimation of the changing collision probability with the spacecraft of the operational navigation systems existing or planned in MEO, i.e., GLONASS, GPS, Beidou and Galileo. The probability that the abandoned objects considered will collide with the operational spacecraft of the navigation constellations is very low, even taking into account the intrinsic eccentricity instability of the disposal orbits. Assuming the present or envisaged configuration of the constellations in MEO, the probability of collision, integrated over 200 years, would be <1/300 with a GLONASS spacecraft, <1/15,000 with a GPS or Beidou spacecraft, and <1/250,000 with a Galileo spacecraft. The worst disposal strategy consists in abandoning satellites and upper stages close to the altitude of the operational constellation (GLONASS), while a re-orbiting a few hundred km away (GPS) is able to guarantee an effective long-term dilution of the collision risk, irrespective of the eccentricity instability due to geopotential and luni-solar perturbations. The disposal strategies applied so far to the GPS satellites should be able to guarantee for at least a few centuries a sustainable MEO environment free of collisions among intact objects. Consequently, there would be no need to adopt disposal schemes targeting also the optimal value of the eccentricity vector. However, it should be pointed out that the GPS disposal strategy was devised well in advance of the Beidou constellation announcement, so most of the abandoned satellites were re-orbited fairly close to the altitude of the new Chinese system. A new re-orbiting approach will be therefore needed in the future.

  6. Extreme Spacecraft Charging in Polar Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Colson, Andrew D.; Minow, Joseph I.; Parker, L. Neergaard

    2012-01-01

    Spacecraft in low altitude, high inclination (including sun -synchronous) orbits are widely used for remote sensing of the Earth fs land surface and oceans, monitoring weather and climate, communications, scientific studies of the upper atmosphere and ionosphere, and a variety of other scientific, commercial, and military applications. These systems episodically charge to frame potentials in the kilovolt range when exposed to space weather environments characterized by a high flux of energetic (approx.10 fs kilovolt) electrons in regions of low background plasma density. Auroral charging conditions are similar in some ways to the space weather conditions in geostationary orbit responsible for spacecraft charging to kilovolt levels. We first review the physics of space environment interactions with spacecraft materials that control auroral charging rates and the anticipated maximum potentials that should be observed on spacecraft surfaces during disturbed space weather conditions. We then describe how the theoretical values compare to the observational history of extreme charging in auroral environments. Finally, a set of extreme DMSP charging events are described varying in maximum negative frame potential from approx.0.6 kV to approx.2 kV, focusing on the characteristics of the charging events that are of importance both to the space system designer and to spacecraft operators. The goal of the presentation is to bridge the gap between scientific studies of auroral charging and the need for engineering teams to understand how space weather impacts both spacecraft design and operations for vehicles on orbital trajectories that traverse auroral charging environments.

  7. Intracellular molecular distributions in spacecraft experiments in orbit around Earth

    NASA Astrophysics Data System (ADS)

    Haranas, Ioannis; Gkigkitzis, Ioannis; Zouganelis, George D.

    2012-04-01

    It is possible that the nucleolous inside the cell plays the role of a "gravity receptor". Furthermore, cells up to 10 μm in diameter can demonstrate some effect due to the redistribution of mitochondria or nucleolous. Effects of gravity should be present in various cell systems where larger objects such as the ribosomes move from cell to cell. In this paper we study the effects of gravity on cells. In particular, we examine the resulting intracellular molecular distribution due to Brownian motion and the ordered distribution of molecules under the action of gravity, where n0 is the number per unit volume at certain level, and n is the number per unit volume above that level. This is an experiment that takes place at a certain orbital altitude in a spacecraft in orbit around Earth, where the acceleration due to the central field is corrected for the oblateness and also the rotation of the Earth. We found that equatorial circular and elliptical orbits have the highest n/n0 ratios. This experiment takes place in circular and elliptical orbits, with eccentricities e = 0, 0.1 and involves a bacterial cell at an orbital altitude of 300 km. We found that n/n0 = 1.00299 and 1.0037 respectively, which is still a 0.6-0.7 % higher than n/n0 = 0.0996685 calculated on the surface of the Earth. Examining mitochondria in similar orbital experiments we found that equatorial orbits result to higher n/n0 ratios. In particular, we found that n/n0 = 8.38119, where an elliptical orbit of eccentricity e = 0.1 results to n/n0 = 13.8525. Both are high above 100%, signifying the importance of Brownian motion over gravity. Our results are of interest to biomedical applications. Molecular concentrations are important for various processes such as the embryogenesis, positional homeostasis and its relation to cell energy expenditure, cell torque, cell deformation, and more. These results indicate that statistical molecular distributions play an important role for the recognition of a

  8. Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration

    NASA Astrophysics Data System (ADS)

    Palermo, Gianluca; Golkar, Alessandro; Gaudenzi, Paolo

    2015-06-01

    As small satellites and Sun Synchronous Earth Observation systems are assuming an increased role in nowadays space activities, including commercial investments, it is of interest to assess how infrastructures could be developed to support the development of such systems and other spacecraft that could benefit from having a data relay service in Low Earth Orbit (LEO), as opposed to traditional Geostationary relays. This paper presents a tradespace exploration study of the architecture of such LEO commercial satellite data relay systems, here defined as Earth Orbiting Support Systems (EOSS). The paper proposes a methodology to formulate architectural decisions for EOSS constellations, and enumerate the corresponding tradespace of feasible architectures. Evaluation metrics are proposed to measure benefits and costs of architectures; lastly, a multicriteria Pareto criterion is used to downselect optimal architectures for subsequent analysis. The methodology is applied to two case studies for a set of 30 and 100 customer-spacecraft respectively, representing potential markets for LEO services in Exploration, Earth Observation, Science, and CubeSats. Pareto analysis shows how increased performance of the constellation is always achieved by an increased node size, as measured by the gain of the communications antenna mounted on EOSS spacecraft. On the other hand, nonlinear trends in optimal orbital altitude, number of satellites per plane, and number of orbital planes, are found in both cases. An upward trend in individual node memory capacity is found, although never exceeding 256 Gbits of onboard memory for both cases that have been considered, assuming the availability of a polar ground station for EOSS data downlink. System architects can use the proposed methodology to identify optimal EOSS constellations for a given service pricing strategy and customer target, thus identifying alternatives for selection by decision makers.

  9. Satellite power system LEO vs GEO assembly issues. [construction in Low Earth Orbits vs GEosynchronous Orbits

    NASA Technical Reports Server (NTRS)

    Mockovciak, J., Jr.; Adornato, R. J.

    1977-01-01

    A strawman crystal-silicon 5-GW Satellite Power System (SPS) concept formed the basis of a study of construction concepts for building a complete SPS in low earth orbit (LEO) or geosynchronous orbit (GEO). Construction scenarios were evolved, including factory-in-space concepts and operations. Design implications imposed on the SPS satellite as a consequence of in-orbit assembly operations, and related attitude control requirements during assembly in LEO or GEO environments, were also evaluated. Results are presented indicating that complete assembly of an operational SPS in LEO, followed by transport to GEO, does not appear technically desirable. The best mix, however, of LEO versus GEO construction activity remains to be resolved.

  10. Single Frequency GPS Orbit Determination for Low Earth Orbiters

    NASA Technical Reports Server (NTRS)

    Bertiger, Willy; Wu, Sien-Chong

    1996-01-01

    A number of missions in the future are planning to use GPS for precision orbit determination. Cost considerations and receiver availability make single frequency GPS receivers attractive if the orbit accuracy requirements can be met.

  11. The orbital distribution of Near-Earth Objects inside Earth's orbit

    NASA Astrophysics Data System (ADS)

    Greenstreet, Sarah; Ngo, Henry; Gladman, Brett

    2012-01-01

    Canada's Near-Earth Object Surveillance Satellite (NEOSSat), set to launch in early 2012, will search for and track Near-Earth Objects (NEOs), tuning its search to best detect objects with a < 1.0 AU. In order to construct an optimal pointing strategy for NEOSSat, we needed more detailed information in the a < 1.0 AU region than the best current model (Bottke, W.F., Morbidelli, A., Jedicke, R., Petit, J.M., Levison, H.F., Michel, P., Metcalfe, T.S. [2002]. Icarus 156, 399-433) provides. We present here the NEOSSat-1.0 NEO orbital distribution model with larger statistics that permit finer resolution and less uncertainty, especially in the a < 1.0 AU region. We find that Amors = 30.1 ± 0.8%, Apollos = 63.3 ± 0.4%, Atens = 5.0 ± 0.3%, Atiras (0.718 < Q < 0.983 AU) = 1.38 ± 0.04%, and Vatiras (0.307 < Q < 0.718 AU) = 0.22 ± 0.03% of the steady-state NEO population. Vatiras are a previously undiscussed NEO population clearly defined in our integrations, whose orbits lie completely interior to that of Venus. Our integrations also uncovered the unexpected production of retrograde orbits from main-belt asteroid sources; this retrograde NEA population makes up ≃0.1% of the steady-state NEO population. The relative NEO impact rate onto Mercury, Venus, and Earth, as well as the normalized distribution of impact speeds, was calculated from the NEOSSat-1.0 orbital model under the assumption of a steady-state. The new model predicts a slightly higher Mercury impact flux.

  12. European activities in exobiology in earth orbit: results and perspectives

    NASA Astrophysics Data System (ADS)

    Horneck, G.

    1999-01-01

    A large portion of European activities in Earth orbit have concentrated on studies of the responses of resistant microbes to the harsh environment of space with the aim of providing experimental evidence testing the hypothesis that interplanetary transfer of life is possible. Various types of microorganisms, such as bacterial or fungal spores, as well as viruses and biomolecules, such as DNA, amino acids and liposomes, have been exposed to selected and combined space conditions outside the Earth's magnetic field (Apollo 16) or in low Earth orbit (Spacelab 1, Spacelab D2, ERA on EURECA, LDEF, BIOPAN on FOTON). Space parameters, such as high vacuum, intense solar ultraviolet radiation, different components of the cosmic radiation field and temperature extremes affected the genetic stability of the organisms in space, leading to increased mutation rates, DNA damage and inactivation. Extraterrestrial solar UV radiation was the most lethal factor. If shielded against the influx of solar UV, spores of Bacillus subtilis survived for more than 5 years in space. Future research will be directed towards long-term studies of microbes in artificial meteorites, as well as of microbial communities from special ecological niches, such as endolithic and endoevaporitic ecosystems. For these studies, the European Space Agency will provide the facility EXPOSE to be accommodated on the External Platform of the International Space Station during the Early Utilization Phase.

  13. GPS World, Innovation: Autonomous Navigation at High Earth Orbits

    NASA Technical Reports Server (NTRS)

    Bamford, William; Winternitz, Luke; Hay, Curtis

    2005-01-01

    Calculating a spacecraft's precise location at high orbital altitudes-22,000 miles (35,800 km) and beyond-is an important and challenging problem. New and exciting opportunities become possible if satellites are able to autonomously determine their own orbits. First, the repetitive task of periodically collecting range measurements from terrestrial antennas to high altitude spacecraft becomes less important-this lessens competition for control facilities and saves money by reducing operational costs. Also, autonomous navigation at high orbital altitudes introduces the possibility of autonomous station keeping. For example, if a geostationary satellite begins to drift outside of its designated slot it can make orbit adjustments without requiring commands from the ground. Finally, precise onboard orbit determination opens the door to satellites flying in formation-an emerging concept for many scientific space applications. The realization of these benefits is not a trivial task. While the navigation signals broadcast by GPS satellites are well suited for orbit and attitude determination at lower altitudes, acquiring and using these signals at geostationary (GEO) and highly elliptical orbits is much more difficult. The light blue trace describes the GPS orbit at approximately 12,550 miles (20,200 km) altitude. GPS satellites were designed to provide navigation signals to terrestrial users-consequently the antenna array points directly toward the earth. GEO and HE0 orbits, however, are well above the operational GPS constellation, making signal reception at these altitudes more challenging. The nominal beamwidth of a Block II/IIA GPS satellite antenna array is approximately 42.6 degrees. At GEO and HE0 altitudes, most of these primary beam transmissions are blocked by the Earth, leaving only a narrow region of nominal signal visibility near opposing limbs of the earth. This region is highlighted in gray. If GPS receivers at GEO and HE0 orbits were designed to use these

  14. Permanent Habitats in Earth-Sol/Mars-Sol Orbit Positions

    NASA Astrophysics Data System (ADS)

    Greenspon, J.

    Project Outpost is a manned Earth-Sol/Mars-Sol platform that enables permanent occupation in deep space. In order to develop the program elements for this complex mission, Project Outpost will rely primarily on existing/nearterm technology and hardware for the construction of its components. For the purposes of this study, four mission requirements are considered: 1. Outpost - Man's 1st purpose-produced effort of space engineering, in which astructure is developed/constructed in an environment completely alien to currentpractices for EVA guidelines. 2. Newton - a concept study developed at StarGate Research, for the development ofa modified Hohmann personnel orbital transport operating between Earth andMars. Newton would serve as the primary crew delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization. 3. Cruis - a concept study developed at StarGate Research, for the development of amodified Hohmann cargo orbital transport operating between Earth and Mars.Cruis would serve as the primary equipment delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization, and 4. Ares/Diana - a more conventional space platform configuration for Lunar andMars orbit is included as a construction baseline. The operations of these assetsare supported, and used for the support, of the outpost. Outpost would be constructed over a 27-year period of launch opportunities into Earth-Sol or Mars-Sol Lagrange orbit (E-S/M-S L1, 4 or 5). The outpost consists of an operations core with a self-contained power generation ability, a docking and maintenance structure, a Scientific Research complex and a Habitation Section. After achieving initial activation, the core will provide the support and energy required to operate the outpost in a 365

  15. NASA Now: Orbital Mechanics: Earth Observing Satellites

    NASA Video Gallery

    This NASA Now program is all about satellites and their orbits. Dr. James Gleason, project scientist for NPP, explains what it takes for a satellite to stay in orbit, why there are different types ...

  16. Degradation of Spacesuit Fabrics in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  17. Orbital acrobatics in the Sun-Earth-Moon system

    NASA Technical Reports Server (NTRS)

    Farquhar, Robert W.; Dunham, D. W.; Hsu, S. C.

    1986-01-01

    Unconventional trajectory techniques for space missions in the Sun-Earth-Moon system, including libration-point orbits, gravity-assist maneuvers, and Earth-return trajectories are reviewed. The ISEE-3/ICE flight experience is used to illustrate the utility of libration-point orbits called halo-orbits. Five lunar gravity-assist maneuvers used by the ISEE-3/ICE spacecraft are discussed. The final lunar swingby sent the spacecraft into a heliocentric trajectory that will eventually intercept Comet Giacobini-Zinner. As an example of the Earth-return trajectory concept, a proposed mission that includes flybys of three comets and two asteroids is described.

  18. LLOFX earth orbit to lunar orbit delta V estimation program user and technical documentation

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The LLOFX computer program calculates in-plane trajectories from an Earth-orbiting space station to Lunar orbit in such a way that the journey requires only two delta V burns (one to leave Earth circular orbit and one to circularize into Lunar orbit). The program requires the user to supply the Space Station altitude and Lunar orbit altitude (in km above the surface), and the desired time of flight for the transfer (in hours). It then determines and displays the trans-Lunar injection (TLI) delta V required to achieve the transfer, the Lunar orbit insertion (LOI) delta V required to circularize the orbit around the Moon, the actual time of flight, and whether the transfer orbit is elliptical or hyperbolic. Return information is also displayed. Finally, a plot of the transfer orbit is displayed.

  19. Earth orbiting technologies for understanding global change

    NASA Astrophysics Data System (ADS)

    Harris, Leonard A.; Johnston, Gordon I.; Hudson, Wayne R.; Couch, Lana M.

    We are all becoming more aware of concerns such as the ozone hole and ozone layer depletion, the build-up of greenhouse gasses and the potential for global climate change, the damage to our lakes and forests from acid rain, and the loss of species and genetic diversity. These are not only of scientific interest, but are of growing public media, federal governmental, and international concern, with the potential for major impacts on the international economy, potential for future development, and global standard of living. Yet our current understanding of how our global environment behaves is embryonic, and does not allow us to predict with confidence the consequences or long term significance of these phenomena. NASA has a significant national responsibility in Global Change research, which will require a major agency investment over the next few decades in obtaining the science data associated with understanding the Earth as a total system. Technology research and development is a natural complement to this national scientific program. In her report to the NASA Administrator, Dr. Sally K. Ride states that Mission to Planet Earth "requires advances in technology to enhance observations, to handle and deliver the enormous quantities of data, and to ensure a long operating life." These three themes (1) space-based observation technologies, (2) data/information technologies, and (3) spacecraft/operations technologies form the basis for NASA's efforts to identify the technologies needed to support the Mission to Planet Earth. In the observation area, developments in spacecraft and space-based instrument technologies are required to enable the accurate measurement of key parameters crucial to the understanding of global change. In the data/information area, developments in technologies are required to enable the long-term documentation of these parameters and the timely understanding of the data. And in the spacecraft/operations area, developments in spacecraft

  20. Space tourism: from earth orbit to the moon

    NASA Astrophysics Data System (ADS)

    Collins, P.

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

  1. Earth's external magnetic fields at low orbital altitudes

    NASA Technical Reports Server (NTRS)

    Klumpar, D. M.

    1990-01-01

    Under our Jun. 1987 proposal, Magnetic Signatures of Near-Earth Distributed Currents, we proposed to render operational a modeling procedure that had been previously developed to compute the magnetic effects of distributed currents flowing in the magnetosphere-ionosphere system. After adaptation of the software to our computing environment we would apply the model to low altitude satellite orbits and would utilize the MAGSAT data suite to guide the analysis. During the first year, basic computer codes to run model systems of Birkeland and ionospheric currents and several graphical output routines were made operational on a VAX 780 in our research facility. Software performance was evaluated using an input matchstick ionospheric current array, field aligned currents were calculated and magnetic perturbations along hypothetical satellite orbits were calculated. The basic operation of the model was verified. Software routines to analyze and display MAGSAT satellite data in terms of deviations with respect to the earth's internal field were also made operational during the first year effort. The complete set of MAGSAT data to be used for evaluation of the models was received at the end of the first year. A detailed annual report in May 1989 described these first year activities completely. That first annual report is included by reference in this final report. This document summarizes our additional activities during the second year of effort and describes the modeling software, its operation, and includes as an attachment the deliverable computer software specified under the contract.

  2. A Cryogenic Propellant Production Depot for Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Potter, Seth D.; Henley, Mark; Guitierrez, Sonia; Fikes, John; Carrington, Connie; Smitherman, David; Gerry, Mark; Sutherlin, Steve; Beason, Phil; Howell, Joe (Technical Monitor)

    2001-01-01

    The cost of access to space beyond low Earth orbit can be lowered if vehicles can refuel in orbit. The power requirements for a propellant depot that electrolyzes water and stores cryogenic oxygen and hydrogen can be met using technology developed for space solar power. A propellant depot is described that will be deployed in a 400 km circular equatorial orbit, receive tanks of water launched into a lower orbit from Earth by gun launch or reusable launch vehicle, convert the water to liquid hydrogen and oxygen, and store Lip to 500 metric tonnes of cryogenic propellants. The propellant stored in the depot can support transportation from low Earth orbit to geostationary Earth orbit, the Moon, LaGrange points, Mars, etc. The tanks are configured in an inline gravity-gradient configuration to minimize drag and settle the propellant. Temperatures can be maintained by body-mounted radiators; these will also provide some shielding against orbital debris. Power is supplied by a pair of solar arrays mounted perpendicular to the orbital plane, which rotate once per orbit to track the Sun. In the longer term, cryogenic propellant production technology can be applied to a larger LEO depot, as well as to the use of lunar water resources at a similar depot elsewhere.

  3. Human Mars Mission: Launch Window from Earth Orbit. Pt. 1

    NASA Technical Reports Server (NTRS)

    Young, Archie

    1999-01-01

    The determination of orbital window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a DELTA V penalty. Usually, because of the DELTA V penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: (1) One impulsive maneuver from a Highly Elliptical Orbit (HEO) (2) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO) (3) One impulsive maneuver from a Low Earth Orbit (LEO) (4) Two impulsive maneuvers from LEO (5) Three impulsive maneuvers from LEO.

  4. Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

    PubMed

    Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

    2010-09-01

    The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life. PMID:20879864

  5. Surface mass variation monitoring from orbit information of GPS-tracked low-Earth orbiters

    NASA Astrophysics Data System (ADS)

    Baur, O.; Weigelt, M. L. B.; Zehentner, N.; Mayer-Gürr, T.; van Dam, T. M.

    2014-12-01

    In the last decade, temporal variations of the gravity field from GRACE inter-satellite observations have become one of the most ubiquitous and valuable sources of information for environmental studies. In order to bridge the likely gap between the present GRACE and the upcoming GRACE follow-on projects, we investigate the potential of gravity field information derived from orbit analysis for surface mass variation detection. The Swarm mission - launched on November 22, 2013 - is the most promising candidate to directly acquire large-scale mass variation information on the Earth's surface in the absence of GRACE. Although the magnetometry mission Swarm has not been designed for gravity field purposes, its three satellites have the appropriate orbit characteristics for such an endeavour. Hence, from an orbit analysis point of view the Swarm satellites are comparable to the CHAMP, GRACE and GOCE spacecraft. In a first study, we assess the stand-alone capability of the Swarm mission for mass variation detection in a real-case environment. For this purpose, we ''approximate'' the Swarm scenario by the GRACE+CHAMP constellation. In a second study, we incorporate tracking observations from a series of additional satellites (e.g., GOCE, MetOp, TanDEM-X, Swarm) and extend the length of the time series according to data availability. We will demonstrate to what extent these measures improve the inference of time-variable features from orbit information. For both studies, in the first step, kinematic orbits of the individual satellites are derived from GPS observations. From these orbits, we compute monthly combined time-variable gravity fields. Finally, we infer mass variation in selected areas from the gravity signal. These results are compared to the findings obtained from mass variation detection exploiting CSR-RL05 gravity fields (the latter serve as ''benchmark solutions'').

  6. Image Stacking Method Application for Low Earth Orbit Faint Objects

    NASA Astrophysics Data System (ADS)

    Tagawa, M.; Matsumoto, H.; Yanagisawa, T.; Kurosaki, H.; Oda, H.; Kitazawa, Y.; Hanada, T.

    2013-09-01

    Space situational awareness is one of the most important actions for safe and sustainable space development and its utilization. Tracking and maintaining debris catalog are the basis of the actions. Current minimum size of objects in the catalog that routinely tracked and updated is approximately 10 cm in the Low Earth Orbit region. This paper proposes collaborative observation of space-based sensors and ground facilities to improve tracking capability in low Earth orbit. This observation geometry based on role-sharing idea. A space-based sensor has advantage in sensitivity and observation opportunity however, it has disadvantages in periodic observation which is essential for catalog maintenance. On the other hand, a ground facility is inferior to space-based sensors in sensitivity however; observation network composed of facilities has an advantage in periodic observation. Whole observation geometry is defined as follows; 1) space-based sensors conduct initial orbit estimation for a target 2) ground facility network tracks the target based on estimated orbit 3) the network observes the target periodically and updates its orbit information. The second phase of whole geometry is based on image stacking method developed by the Japan aerospace exploration agency and this method is verified for objects in geostationary orbit. This method enables to detect object smaller than a nominal size limitation by stacking faint light spot along archived time-series frames. The principle of this method is prediction and searching target's motion on the images. It is almost impossible to apply the method to objects in Low Earth Orbit without proper orbit information because Low Earth Orbit objects have varied orbital characteristics. This paper discusses whether or not initial orbit estimation results given by space-based sensors have enough accuracy to apply image stacking method to Low Earth Orbit objects. Ground-based observation procedure is assumed as being composed of

  7. Space radiation dosimetry in low-Earth orbit and beyond

    NASA Technical Reports Server (NTRS)

    Benton, E. R.; Benton, E. V.

    2001-01-01

    Space radiation dosimetry presents one of the greatest challenges in the discipline of radiation protection. This is a result of both the highly complex nature of the radiation fields encountered in low-Earth orbit (LEO) and interplanetary space and of the constraints imposed by spaceflight on instrument design. This paper reviews the sources and composition of the space radiation environment in LEO as well as beyond the Earth's magnetosphere. A review of much of the dosimetric data that have been gathered over the last four decades of human space flight is presented. The different factors affecting the radiation exposures of astronauts and cosmonauts aboard the International Space Station (ISS) are emphasized. Measurements made aboard the Mir Orbital Station have highlighted the importance of both secondary particle production within the structure of spacecraft and the effect of shielding on both crew dose and dose equivalent. Roughly half the dose on ISS is expected to come from trapped protons and half from galactic cosmic rays (GCRs). The dearth of neutron measurements aboard LEO spacecraft and the difficulty inherent in making such measurements have led to large uncertainties in estimates of the neutron contribution to total dose equivalent. Except for a limited number of measurements made aboard the Apollo lunar missions, no crew dosimetry has been conducted beyond the Earth's magnetosphere. At the present time we are forced to rely on model-based estimates of crew dose and dose equivalent when planning for interplanetary missions, such as a mission to Mars. While space crews in LEO are unlikely to exceed the exposure limits recommended by such groups as the NCRP, dose equivalents of the same order as the recommended limits are likely over the course of a human mission to Mars. c2001 Elsevier Science B.V. All rights reserved.

  8. Space radiation dosimetry in low-Earth orbit and beyond.

    PubMed

    Benton, E R; Benton, E V

    2001-09-01

    Space radiation dosimetry presents one of the greatest challenges in the discipline of radiation protection. This is a result of both the highly complex nature of the radiation fields encountered in low-Earth orbit (LEO) and interplanetary space and of the constraints imposed by spaceflight on instrument design. This paper reviews the sources and composition of the space radiation environment in LEO as well as beyond the Earth's magnetosphere. A review of much of the dosimetric data that have been gathered over the last four decades of human space flight is presented. The different factors affecting the radiation exposures of astronauts and cosmonauts aboard the International Space Station (ISS) are emphasized. Measurements made aboard the Mir Orbital Station have highlighted the importance of both secondary particle production within the structure of spacecraft and the effect of shielding on both crew dose and dose equivalent. Roughly half the dose on ISS is expected to come from trapped protons and half from galactic cosmic rays (GCRs). The dearth of neutron measurements aboard LEO spacecraft and the difficulty inherent in making such measurements have led to large uncertainties in estimates of the neutron contribution to total dose equivalent. Except for a limited number of measurements made aboard the Apollo lunar missions, no crew dosimetry has been conducted beyond the Earth's magnetosphere. At the present time we are forced to rely on model-based estimates of crew dose and dose equivalent when planning for interplanetary missions, such as a mission to Mars. While space crews in LEO are unlikely to exceed the exposure limits recommended by such groups as the NCRP, dose equivalents of the same order as the recommended limits are likely over the course of a human mission to Mars. PMID:11863032

  9. Natural orbital environment definition guidelines for use in aerospace vehicle development

    NASA Technical Reports Server (NTRS)

    Anderson, B. Jeffrey (Editor); Smith, Robert E. (Compiler)

    1994-01-01

    This document provides definitions of the natural near-Earth space environment suitable for use in the initial development/design phase of any space vehicle. The natural environment includes the neutral atmosphere, plasma, charged particle radiation, electromagnetic radiation (EMR), meteoroids, orbital debris, magnetic field, physical and thermal constants, and gravitational field. Communications and other unmanned satellites operate in geosynchronous-Earth orbit (GEO); therefore, some data are given for GEO, but emphasis is on altitudes from 200 km to 1000 km (low-Earth orbit (LEO)). This document does not cover the induced environment of other effects resulting from presence of the space vehicle. Manmade factors are included as part of the ambient natural environment; i.e., orbital debris and radio frequency (RF) noise generated on Earth, because they are not caused by the presence of the space vehicle but form part of the ambient environment that the space vehicle experiences.

  10. Atomic oxygen effects on POSS polyimides in low earth orbit.

    PubMed

    Minton, Timothy K; Wright, Michael E; Tomczak, Sandra J; Marquez, Sara A; Shen, Linhan; Brunsvold, Amy L; Cooper, Russell; Zhang, Jianming; Vij, Vandana; Guenthner, Andrew J; Petteys, Brian J

    2012-02-01

    Kapton polyimde is extensively used in solar arrays, spacecraft thermal blankets, and space inflatable structures. Upon exposure to atomic oxygen in low Earth orbit (LEO), Kapton is severely eroded. An effective approach to prevent this erosion is to incorporate polyhedral oligomeric silsesquioxane (POSS) into the polyimide matrix by copolymerizing POSS monomers with the polyimide precursor. The copolymerization of POSS provides Si and O in the polymer matrix on the nano level. During exposure of POSS polyimide to atomic oxygen, organic material is degraded, and a silica passivation layer is formed. This silica layer protects the underlying polymer from further degradation. Laboratory and space-flight experiments have shown that POSS polyimides are highly resistant to atomic-oxygen attack, with erosion yields that may be as little as 1% those of Kapton. The results of all the studies indicate that POSS polyimide would be a space-survivable replacement for Kapton on spacecraft that operate in the LEO environment. PMID:22188314

  11. Earth Oblateness in Terms of Satellite Orbital Periods.

    PubMed

    Blitzer, L

    1959-02-01

    A theoretical equation relating the earth's oblateness to the anomalistic and nodical periods and orbit parameters of an earth satellite is presented. In the absence of exact data on nodical periods, Vanguard prediction data are utilized to obtain a check calculation for the oblateness and to establish the validity of the method. PMID:17746560

  12. Effects of target fragmentation on evaluation of LET spectra from space radiation in low-earth orbit (LEO) environment: impact on SEU predictions

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Cucinotta, F. A.; Wilson, J. W.; Badhwar, G. D.; O'Neill, P. M.; Badavi, F. F.

    1995-01-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.

  13. Effects of target fragmentation on evaluation of LET spectra from space radiation in low-earth orbit (LEO) environment: impact on SEU predictions.

    PubMed

    Shinn, J L; Cucinotta, F A; Wilson, J W; Badhwar, G D; O'Neill, P M; Badavi, F F

    1995-12-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects. PMID:11541192

  14. Effects of Target Fragmentation on Evaluation of LET Spectra From Space Radiation in Low-Earth Orbit (LEO) Environment: Impact on SEU Predictions

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Cucinotta, F. A.; Badhwar, G. D.; ONeill, P. M.; Badavi, F. F.

    1995-01-01

    Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.

  15. Gateway: An earth orbiting transportation node

    NASA Technical Reports Server (NTRS)

    1988-01-01

    University of Texas Mission Design (UTMD) has outlined the components that a space based transportation facility must include in order to support the first decade of Lunar base buildup. After studying anticipated traffic flow to and from the hub, and taking into account crew manhour considerations, propellant storage, orbital transfer vehicle maintenance requirements, and orbital mechanics, UTMD arrived at a design for the facility. The amount of activity directly related to supporting Lunar base traffic is too high to allow the transportation hub to be part of the NASA Space Station. Instead, a separate structure should be constructed and dedicated to handling all transportation-related duties. UTMD found that the structure (named Gateway) would need a permanent crew of four to perform maintenance tasks on the orbital transfer and orbital maneuvering vehicles and to transfer payload from launch vehicles to the orbital transfer vehicles. In addition, quarters for 4 more persons should be allocated for temporary accommodation of Lunar base crew passing through Gateway. UTMD was careful to recommend an expendable structure that can adapt to meet the growing needs of the American space program.

  16. Low-Earth Orbit Determination from Gravity Gradient Measurements

    NASA Astrophysics Data System (ADS)

    Sun, Xiucong; Chen, Pei; Macabiau, Christophe; Han, Chao

    2016-06-01

    An innovative orbit determination method which makes use of gravity gradients for Low-Earth-Orbiting satellites is proposed. The measurement principle of gravity gradiometry is briefly reviewed and the sources of measurement error are analyzed. An adaptive hybrid least squares batch filter based on linearization of the orbital equation and unscented transformation of the measurement equation is developed to estimate the orbital states and the measurement biases. The algorithm is tested with the actual flight data from the European Space Agency's Gravity field and steady-state Ocean Circulation Explorer (GOCE). The orbit determination results are compared with the GPS-derived orbits. The radial and cross-track position errors are on the order of tens of meters, whereas the along-track position error is over one order of magnitude larger. The gravity gradient based orbit determination method is promising for potential use in GPS-denied spacecraft navigation.

  17. Low Earth Orbital Atomic Oxygen Interactions With Materials

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Miller, Sharon K.; deGroh, Kim K.

    2004-01-01

    Atomic oxygen is formed in the low Earth orbital environment (LEO) by photo dissociation of diatomic oxygen by short wavelength (< 243 nm) solar radiation which has sufficient energy to break the 5.12 eV O2 diatomic bond in an environment where the mean free path is sufficiently long ( 108 meters) that the probability of reassociation or the formation of ozone (O3) is small. As a consequence, between the altitudes of 180 and 650 km, atomic oxygen is the most abundant species. Spacecraft impact the atomic oxygen resident in LEO with sufficient energy to break hydrocarbon polymer bonds, causing oxidation and thinning of the polymers due to loss of volatile oxidation products. Mitigation techniques, such as the development of materials with improved durability to atomic oxygen attack, as well as atomic oxygen protective coatings, have been employed with varying degrees of success to improve durability of polymers in the LEO environment. Atomic oxygen can also oxidize silicones and silicone contamination to produce non-volatile silica deposits. Such contaminants are present on most LEO missions and can be a threat to performance of optical surfaces. The LEO atomic oxygen environment, its interactions with materials, results of space testing, computational modeling, mitigation techniques, and ground laboratory simulation procedures and issues are presented.

  18. 2012 Earth-Orbiting Heliophysics Fleet

    NASA Video Gallery

    Since Sentinels of the Heliosphere in 2008, there have been a few new missions, and a few missions have been shut down. As of Fall of 2012, here's a tour of the NASA Near-Earth Heliophysics fleet, ...

  19. Platinum in Earth surface environments

    NASA Astrophysics Data System (ADS)

    Reith, F.; Campbell, S. G.; Ball, A. S.; Pring, A.; Southam, G.

    2014-04-01

    Platinum (Pt) is a rare precious metal that is a strategic commodity for industries in many countries. The demand for Pt has more than doubled in the last 30 years due to its role in the catalytic conversion of CO, hydrocarbons and NOx in modern automobiles. To explore for new Pt deposits, process ores and deal with ecotoxicological effects of Pt mining and usage, the fundamental processes and pathways of Pt dispersion and re-concentration in surface environments need to be understood. Hence, the aim of this review is to develop a synergistic model for the cycling of Pt in Earth surface environments. This is achieved by integrating the geological/(biogeo)chemical literature, which focuses on naturally occurring Pt mobility around ore deposits, with the environmental/ecotoxicological literature dealing with anthropogenic Pt dispersion. In Pt deposits, Pt occurs as sulfide-, telluride- and arsenide, native metal and alloyed to other PGEs and iron (Fe). Increased mining and utilization of Pt combined with the burning of fossil fuels have led to the dispersion of Pt-containing nano- and micro-particles. Hence, soils and sediments in industrialized areas, urban environments and along major roads are now commonly Pt enriched. Platinum minerals, nuggets and anthropogenic particles are transformed by physical and (bio)geochemical processes. Complexation of Pt ions with chloride, thiosulfate, ammonium, cyanide, low- and high molecular weight organic acids (LMWOAs and HMWOAs) and siderophores can facilitate Pt mobilization. Iron-oxides, clays, organic matter and (micro)biota are known to sequester Pt-complexes and -particles. Microbes and plants are capable of bioaccumulating and reductively precipitating mobile Pt complexes. Bioaccumulation can lead to toxic effects on plants and animals, including humans. (Bio)mineralization in organic matter-rich sediments can lead to the formation of secondary Pt particles and -grains. Ultimately, Pt is enriched in oceanic sediments

  20. Geosynchronous earth orbit base propulsion - electric propulsion options

    SciTech Connect

    Palaszewski, B.

    1987-01-01

    Electric propulsion and chemical propulsion requirements for a geosynchronous earth orbit (GEO) base were analyzed. The base is resupplied from the Space Station's low earth orbit. Orbit-transfer Delta-Vs, nodal-regression Delta-Vs and orbit-maintenance Delta-Vs were considered. For resupplying the base, a cryogenic oxygen/hydrogen (O2/H2) orbital transfer vehicle (OTV) is currently-baselined. Comparisons of several electric propulsion options with the O2/H2 OTV were conducted. Propulsion requirements for missions related to the GEO base were also analyzed. Payload data for the GEO missions were drawn from current mission data bases. Detailed electric propulsion module designs are presented. Mission analyses and propulsion analyses for the GEO-delivered payloads are included. 23 references.

  1. Technologies of diffractive imaging system for high-resolution earth observation from geostationary orbit

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoli; Su, Yun; Jiao, Jianchao

    2013-08-01

    High-resolution earth observation from geostationary orbit (GEO) is a good way to satisfy the increased time resolution for resource, environment and disaster monitor. Earth observation from geostationary orbit will require optical remote sensor with ultra-large aperture. Given size, weight and launch ability constraints, as well as cost consideration, the traditional monolithic aperture optical system couldn't satisfy the need. This paper gives a new method, the diffractive imaging system. Diffract ive imaging system is a feasible way to realize high-resolution earth observation from geostationary orbit. The principle of diffract ive imaging system is introduced firstly, then, the primary design of remote sensor with 1m resolution from geostationary orbit using diffractive imaging system is analyzed. Finally, the key technologies are analyzed and feasible solutions are given.

  2. Earth orbital teleoperator visual system evaluation program

    NASA Technical Reports Server (NTRS)

    Shields, N. L., Jr.; Kirkpatrick, M., III; Frederick, P. N.; Malone, T. B.

    1975-01-01

    Empirical tests of range estimation accuracy and resolution, via television, under monoptic and steroptic viewing conditions are discussed. Test data are used to derive man machine interface requirements and make design decisions for an orbital remote manipulator system. Remote manipulator system visual tasks are given and the effects of system parameters of these tasks are evaluated.

  3. Simulation of interference between Earth stations and Earth-orbiting satellites

    NASA Technical Reports Server (NTRS)

    Bishop, D. F.

    1994-01-01

    It is often desirable to determine the potential for radio frequency interference between earth stations and orbiting spacecraft. This information can be used to select frequencies for radio systems to avoid interference or it can be used to determine if coordination between radio systems is necessary. A model is developed that will determine the statistics of interference between earth stations and elliptical orbiting spacecraft. The model uses orbital dynamics, detailed antenna patterns, and spectral characteristics to obtain accurate levels of interference at the victim receiver. The model is programmed into a computer simulation to obtain long-term statistics of interference. Two specific examples are shown to demonstrate the model. The first example is a simulation of interference from a fixed-satellite earth station to an orbiting scatterometer receiver. The second example is a simulation of interference from earth-exploration satellites to a deep-space earth station.

  4. Need for expanded environmental measurement capabilities in geosynchronous Earth orbit

    NASA Technical Reports Server (NTRS)

    Mercanti, Enrico P.

    1991-01-01

    The proliferation of environmental satellites in low altitude earth orbit (LEO) has demonstrated the usefulness of earth remote sensing from space. As use of the technology grows, the limitations of LEO missions become more apparent. Many inadequacies can be met by remote sensing from geosynchronous earth orbits (GEO) that can provide high temporal resolution, consistent viewing of specific earth targets, long sensing dwell times with varying sun angles, stereoscopic coverage, and correlative measurements with ground and LEO observations. An environmental platform in GEO is being studied by NASA. Small research satellite missions in GEO were studied (1990) at GSFC. Some recent independent assessments of NASA Earth Science Programs recommend accelerating the earlier deployment of smaller missions.

  5. Solar concentrator degradation in Low Earth Orbit (LEO)

    NASA Technical Reports Server (NTRS)

    Thomas, R. G.

    1983-01-01

    The use of parabolically or spherically-shaped mirrors is being considered in order to increase the solar energy intensity on solar cells. Their use will significantly decrease the size and number of the cells needed for a particular application, hence the total array cost. Questions arise, however, regarding the long-term (five to ten years) efficiency of these devices. Performance degradation of the mirror surfaces might result from known hostile elements in the low earth orbit (LEO) environment (150-350 nautical miles). The degradation issue is addressed in light of present knowledge of this environment. The following characteristics of the LEO environment are identified for study: (1) the vacuum of space; (2) sputtering by the residual atoms and particles in space; (3) solar electromagnetic radiation; (4) contamination of the mirror surface; (5) atomic oxygen interactions with the surface; (6) bombardment of the surface by meteoroids; and (7) irradiation of the surface by ionizing particles (protons). Using the best available information for the magnitudes of the necessary quantities, a mathematical analysis was carried out, where possible, to determine the degradation in reflectance or other loss caused by each characteristic. Otherwise, reasonable estimates are made of corresponding losses, based on already published data.

  6. An Investigation of Low Earth Orbit Internal Charging

    NASA Technical Reports Server (NTRS)

    NeergaardParker, Linda; Minow, Joseph I.; Willis, Emily M.

    2014-01-01

    Low Earth orbit is usually considered a relatively benign environment for internal charging threats due to the low flux of penetrating electrons with energies of a few MeV that are encountered over an orbit. There are configurations, however, where insulators and ungrounded conductors used on the outside of a spacecraft hull may charge when exposed to much lower energy electrons of some 100's keV in a process that is better characterized as internal charging than surface charging. For example, the minimal radiation shielding afforded by thin thermal control materials such as metalized polymer sheets (e.g., aluminized Kapton or Mylar) and multilayer insulation may allow electrons of 100's of keV to charge underlying materials. Yet these same thermal control materials protect the underlying insulators and ungrounded conductors from surface charging currents due to electrons and ions at energies less than a few keV as well as suppress the photoemission, secondary electron, and backscattered electron processes associated with surface charging. We investigate the conditions required for this low Earth orbit "internal charging" to occur and evaluate the environments for which the process may be a threat to spacecraft. First, we describe a simple one-dimensional internal charging model that is used to compute the charge accumulation on materials under thin shielding. Only the electron flux that penetrates exposed surface shielding material is considered and we treat the charge balance in underlying insulation as a parallel plate capacitor accumulating charge from the penetrating electron flux and losing charge due to conduction to a ground plane. Charge dissipation due to conduction can be neglected to consider the effects of charging an ungrounded conductor. In both cases, the potential and electric field is computed as a function of time. An additional charge loss process is introduced due to an electrostatic discharge current when the electric field reaches a

  7. 3D Orbit Visualization for Earth-Observing Missions

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  8. Orbital Debris and Future Environment Remediation

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2011-01-01

    This slide presentation is an overview of the historical and current orbital debris environment. Included is information about: Projected growth of the future debris population, The need for active debris removal (ADR), A grand challenge for the 21st century and The forward path

  9. Low Earth Orbital Atomic Oxygen Interactions With Spacecraft Materials

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Miller, Sharon K.

    2004-01-01

    Atomic oxygen, formed in Earth s thermosphere, interacts readily with many materials on spacecraft flying in low Earth orbit (LEO). All hydrocarbon based polymers and graphite are easily oxidized upon the impact of approx.4.5 eV atomic oxygen as the spacecraft ram into the residual atmosphere. The resulting interactions can change the morphology and reduce the thickness of these materials. Directed atomic oxygen erosion will result in the development of textured surfaces on all materials with volatile oxidation products. Examples from space flight samples are provided. As a result of the erosive properties of atomic oxygen on polymers and composites, protective coatings have been developed and are used to increase the functional life of polymer films and composites that are exposed to the LEO environment. The atomic oxygen erosion yields for actual and predicted LEO exposure of numerous materials are presented. Results of in-space exposure of vacuum deposited aluminum protective coatings on polyimide Kapton indicate high rates of degradation are associated with aluminum coatings on both surfaces of the Kapton. Computational modeling predictions indicate that less trapping of the atomic oxygen occurs, with less resulting damage, if only the space-exposed surface is coated with vapor deposited aluminum rather than having both surfaces coated.

  10. The Near-Earth Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Xapsos, Michael

    2008-01-01

    This viewgraph presentation reviews the effects of the Near-Earth space radiation environment on NASA missions. Included in this presentation is a review of The Earth s Trapped Radiation Environment, Solar Particle Events, Galactic Cosmic Rays and Comparison to Accelerator Facilities.

  11. The Sun and Earth's Space Environment

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2009-01-01

    Earth's space environment is closely controlled by solar variability over various time scales. Solar variability is characterized by its output in the form of mass and electromagnetic output. Solar mass emission also interacts with mass entering into the heliosphere in the form of cosmic rays and neutral material. This paper provides an overview of how the solar variability affects Earth's space environment.

  12. Active Debris Removal mission design in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Martin, Th.; Pérot, E.; Desjean, M.-Ch.; Bitetti, L.

    2013-03-01

    Active Debris Removal (ADR) aims at removing large sized intact objects ― defunct satellites, rocket upper-stages ― from space crowded regions. Why? Because they constitute the main source of the long-term debris environment deterioration caused by possible future collisions with fragments and worse still with other intact but uncontrolled objects. In order to limit the growth of the orbital debris population in the future (referred to as the Kessler syndrome), it is now highly recommended to carry out such ADR missions, together with the mitigation measures already adopted by national agencies (such as postmission disposal). At the French Space Agency, CNES, and in the frame of advanced studies, the design of such an ADR mission in Low Earth Orbit (LEO) is under evaluation. A two-step preliminary approach has been envisaged. First, a reconnaissance mission based on a small demonstrator (˜500 kg) rendezvousing with several targets (observation and in-flight qualification testing). Secondly, an ADR mission based on a larger vehicle (inherited from the Orbital Transfer Vehicle (OTV) concept) being able to capture and deorbit several preselected targets by attaching a propulsive kit to these targets. This paper presents a flight dynamics level tradeoff analysis between different vehicle and mission concepts as well as target disposal options. The delta-velocity, times, and masses required to transfer, rendezvous with targets and deorbit are assessed for some propelled systems and propellant less options. Total mass budgets are then derived for two end-to-end study cases corresponding to the reconnaissance and ADR missions mentioned above.

  13. Human Mars Mission: Launch Window from Earth Orbit. Pt. 1

    NASA Technical Reports Server (NTRS)

    Young, Archie

    1999-01-01

    The determination of orbital window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to the earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a delta V penalty. Usually, because of the delta V penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: 1) One impulsive maneuver from a Highly Elliptical Orbit (HEO); 2) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO); 3) One impulsive maneuver from a Low Earth Orbit (LEO); 4) Two impulsive maneuvers form LEO; and 5) Three impulsive maneuvers form LEO. The formulation of these five different launch window modes provides a rapid means of generating realistic parametric data

  14. Human Exploration Missions Study Launch Window from Earth Orbit

    NASA Technical Reports Server (NTRS)

    Young, Archie

    2001-01-01

    The determination of orbital launch window characteristics is of major importance in the analysis of human interplanetary missions and systems. The orbital launch window characteristics are directly involved in the selection of mission trajectories, the development of orbit operational concepts, and the design of orbital launch systems. The orbital launch window problem arises because of the dynamic nature of the relative geometry between outgoing (departure) asymptote of the hyperbolic escape trajectory and the earth parking orbit. The orientation of the escape hyperbola asymptotic relative to earth is a function of time. The required hyperbola energy level also varies with time. In addition, the inertial orientation of the parking orbit is a function of time because of the perturbations caused by the Earth's oblateness. Thus, a coplanar injection onto the escape hyperbola can be made only at a point in time when the outgoing escape asymptote is contained by the plane of parking orbit. Even though this condition may be planned as a nominal situation, it will not generally represent the more probable injection geometry. The general case of an escape injection maneuver performed at a time other than the coplanar time will involve both a path angle and plane change and, therefore, a Delta(V) penalty. Usually, because of the Delta(V) penalty the actual departure injection window is smaller in duration than that determined by energy requirement alone. This report contains the formulation, characteristics, and test cases for five different launch window modes for Earth orbit. These modes are: (1) One impulsive maneuver from a Low Earth Orbit (LEO), (2) Two impulsive maneuvers from LEO, (3) Three impulsive maneuvers from LEO, (4) One impulsive maneuvers from a Highly Elliptical Orbit (HEO), (5) Two impulsive maneuvers from a Highly Elliptical Orbit (HEO) The formulation of these five different launch window modes provides a rapid means of generating realistic parametric

  15. Autonomous Navigation Improvements for High-Earth Orbiters Using GPS

    NASA Technical Reports Server (NTRS)

    Long, Anne; Kelbel, David; Lee, Taesul; Garrison, James; Carpenter, J. Russell; Bauer, F. (Technical Monitor)

    2000-01-01

    The Goddard Space Flight Center is currently developing autonomous navigation systems for satellites in high-Earth orbits where acquisition of the GPS signals is severely limited This paper discusses autonomous navigation improvements for high-Earth orbiters and assesses projected navigation performance for these satellites using Global Positioning System (GPS) Standard Positioning Service (SPS) measurements. Navigation performance is evaluated as a function of signal acquisition threshold, measurement errors, and dynamic modeling errors using realistic GPS signal strength and user antenna models. These analyses indicate that an autonomous navigation position accuracy of better than 30 meters root-mean-square (RMS) can be achieved for high-Earth orbiting satellites using a GPS receiver with a very stable oscillator. This accuracy improves to better than 15 meters RMS if the GPS receiver's signal acquisition threshold can be reduced by 5 dB-Hertz to track weaker signals.

  16. Asteroids on Earth-like orbits and their origin

    NASA Astrophysics Data System (ADS)

    Brasser, R.; Wiegert, P.

    2008-06-01

    The orbit of 1991 VG and a set of other asteroids whose orbits are very similar to that of the Earth have been examined. Its origin has been speculated to be a returning spacecraft, lunar ejecta or a low-inclination Amor- or Apollo-class object. The latter is arguably the more likely source, which has been investigated here. The impact probability for these objects has been calculated, and while it is larger than that of a typical near-Earth asteroid (NEA), it is still less than 1:200000 over the next 5000 yr. In addition, the probability of an NEA ever ending up on an Earth-like orbit has been obtained from numerical simulations and turned out to be about 1:20000, making this a rare class of objects. The typical time spent in this state is about 10000 yr, much less than the typical NEA lifetime of 10 Myr.

  17. Dynamics of Drag Free Formations in Earth Orbit

    NASA Technical Reports Server (NTRS)

    Ploen, Scott R.; Scharf, Daniel P.; Hadaegh, Fred. Y.; Acikmese, A. Behcet

    2004-01-01

    In this paper the translational equations of motion of a formation of n spacecraft in Earth orbit, n(sub f) of which are drag-free spacecraft, are derived in a coordinate-free manner using the balance of linear momentum and direct tensor notation. A drag-free spacecraft consists of a spacecraft bus and a proof mass shielded from external disturbances in an internal cavity. By controlling the spacecraft so that the proof mass remains centered in the cavity, the spacecraft follows a purely gravitational orbit. The results described in this paper provide a first step toward coupling drag-free control technology with formation flying in order to mitigate the effect of differential aerodynamic drag on formation flying missions (e.g., Earth imaging applications) in low Earth orbit.

  18. Zodiacal emission. I - Dust near the earth's orbit

    NASA Technical Reports Server (NTRS)

    Reach, William T.

    1988-01-01

    The infrared emission of interplanetary dust near the earth's orbit is derived from IRAS observations of the gradient of in-ecliptic brightness tangent to the earth's orbit, and the annual variation of the ecliptic polar brightness. Models with five grain constituents and three size distributions are compared with the observations. The observed emission is twice as bright as predicted; this discrepancy is due either to calibration errors or to enhanced radiative efficiency of 'fluffy' particles. Graphite and magnetite particles are ruled out because they are too hot. The size distribution is constrained to be less steep than that derived from lunar microcrater studies, and is consistent with that obtained by earth-orbiting satellites. Nonhomogeneous silicate grains with 3 percent graphite impurity produce the best fit to the spectrum. The model predictions extend from 3 microns to 1 mm, for use in analyzing future infrared background observations.

  19. Relativity mission with two counter-orbiting polar satellites. [nodal dragging effect on earth orbiting satellites

    NASA Technical Reports Server (NTRS)

    Van Patten, R. A.; Everitt, C. W. F.

    1975-01-01

    In 1918, J. Lense and H. Thirring calculated that a moon in orbit around a massive rotating planet would experience a nodal dragging effect due to general relativity. We describe an experiment to measure this effect with two counter-orbiting drag-free satellites in polar earth orbit. For a 2 1/2 year experiment, the measurement accuracy should approach 1%. In addition to precision tracking data from existing ground stations, satellite-to-satellite Doppler ranging data are taken at points of passing near the poles. New geophysical information on both earth harmonics and tidal effects is inherent in the polar ranging data.

  20. Controllability of Large SEP for Earth Orbit Raising

    NASA Technical Reports Server (NTRS)

    Woodcock, Gordon

    2004-01-01

    A six-degree-of-freedom (6DOF) simulation was constructed and exercised for a large solar electric propulsion (SEP) vehicle operating in low Earth orbit Nominal power was 500 kWe, with the large array sizes implied. Controllability issues, including gravity gradient, roll maneuvering for Sun tracking, and flexible arrays, and flight control methods, were investigated. Initial findings are that a SEP vehicle of this size is controllable and could be used for orbit raising of heavy payloads.

  1. A method for capturing asteroids into earth satellite orbits

    NASA Astrophysics Data System (ADS)

    Ledkov, A. A.; Eismont, N. A.; Nazirov, R. R.; Boyarsky, M. N.

    2015-08-01

    At present, the capture of a suitable asteroid into an Earth satellite orbit is proposed as one of the methods for investigating asteroids within the framework of manned missions. Once the asteroid has been transferred to such an orbit, an expedition with the participation of astronauts is planned to the asteroid surface, where research is carried out and asteroid rock samples are selected and subsequently delivered to the Earth. It is in this way that the American Keck project is described at the current planning and preliminary design stage. In this paper, we solve the capture problem by a method alternative to that planned in the Keck project.

  2. Long-Duration Human Habitation Beyond Low-Earth Orbit: Why is the Near Future Critical?

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  3. A Comprehensive Survey of Earth-Moon Libration Orbits: Stationkeeping Strategies And Intra-Orbit Transfers

    NASA Technical Reports Server (NTRS)

    Folta, David; Vaughn, Frank

    2004-01-01

    Cislunar space is a readily accessible region that may well develop into a prime staging area in the effort to colonize space near the Earth or to colonize the moon. While there have been statements made by various NASA programs regarding placement of resources in orbit about the Earth-Moon Lagrangian locations, there is no survey of the total cost associated with attaining and maintaining these unique orbits in an optimal fashion. Transfer trajectories between these orbits required for assembly, servicing, and positioning of these resources have not been extensively investigated. These orbits are dynamically similar to those used for the Sun-Earth missions, but differences in governing gravitational ratios and perturbation sources result in their having their own unique characteristics.

  4. NAVIGATION PERFORMANCE IN HIGH EARTH ORBITS USING NAVIGATOR GPS RECEIVER

    NASA Technical Reports Server (NTRS)

    Bamford, William; Naasz, Bo; Moreau, Michael C.

    2006-01-01

    NASA GSFC has developed a GPS receiver that can acquire and track GPS signals with sensitivity significantly lower than conventional GPS receivers. This opens up the possibility of using GPS based navigation for missions in high altitude orbit, such as Geostationary Operational Environmental Satellites (GOES) in a geostationary orbit, and the Magnetospheric MultiScale (MMS) Mission, in highly eccentric orbits extending to 12 Earth radii and higher. Indeed much research has been performed to study the feasibility of using GPS navigation in high Earth orbits and the performance achievable. Recently, GSFC has conducted a series of hardware in-the-loop tests to assess the performance of this new GPS receiver in various high Earth orbits of interest. Tracking GPS signals to down to approximately 22-25 dB-Hz, including signals from the GPS transmitter side-lobes, steady-state navigation performance in a geostationary orbit is on the order of 10 meters. This paper presents the results of these tests, as well as sensitivity analysis to such factors as ionosphere masks, use of GPS side-lobe signals, and GPS receiver sensitivity.

  5. Autonomous scheduling technology for Earth orbital missions

    NASA Technical Reports Server (NTRS)

    Srivastava, S.

    1982-01-01

    The development of a dynamic autonomous system (DYASS) of resources for the mission support of near-Earth NASA spacecraft is discussed and the current NASA space data system is described from a functional perspective. The future (late 80's and early 90's) NASA space data system is discussed. The DYASS concept, the autonomous process control, and the NASA space data system are introduced. Scheduling and related disciplines are surveyed. DYASS as a scheduling problem is also discussed. Artificial intelligence and knowledge representation is considered as well as the NUDGE system and the I-Space system.

  6. Orbital Noise in the Earth System and Climate Fluctuations

    NASA Technical Reports Server (NTRS)

    Liu, Han-Shou; Smith, David E. (Technical Monitor)

    2001-01-01

    Frequency noise in the variations of the Earth's obliquity (tilt) can modulate the insolation signal for climate change. Including this frequency noise effect on the incoming solar radiation, we have applied an energy balance climate model to calculate the climate fluctuations for the past one million years. Model simulation results are in good agreement with the geologically observed paleoclimate data. We conclude that orbital noise in the Earth system may be the major cause of the climate fluctuation cycles.

  7. SEVO (Space Environment Viability of Organics) Preliminary Results from Orbit

    NASA Technical Reports Server (NTRS)

    Cook, A.; Ehrenfreund, P.; Mattioda, A.; Quinn, R.; Ricco, A. J.; Bramall, N.; Chittenden, J.; Bryson, K.; Minelli, G.

    2012-01-01

    SEVO (Space Environment Viability of Organics) is one of two astrobiology experiments onboard the NASA Organism/Organics Exposure to Orbital Stresses (O/OREOS) cubesat, launched in November 2010. The satellite is still operational with nominal performance and records data on a regular basis. In the SEVO experiment, four astrobiologically relevant organic thin films are exposed to radiation in low-earth orbit, including the unfiltered solar spectrum from approximately 120 - 2600 nm. The thin films are contained in each of four separate micro-environments: an atmosphere containing CO2, a low relative humidity (approximately 2%) atmosphere, an inert atmosphere representative of interstellar/interplanetary space, and a SiO2 mineral surface to measure the effects of surface catalysis. The UV/Vis spectrum of each sample is monitored in situ, with a spectrometer onboard the satellite.

  8. Electric Propulsion for Low Earth Orbit Communication Satellites

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.

    1997-01-01

    Electric propulsion was evaluated for orbit insertion, satellite positioning and de-orbit applications on big (hundreds of kilograms) and little (tens of kilograms) low earth orbit communication satellite constellations. A simple, constant circumferential thrusting method was used. This technique eliminates the complex guidance and control required when shading of the solar arrays must be considered. Power for propulsion was assumed to come from the existing payload power. Since the low masses of these satellites enable multiple spacecraft per launch, the ability to add spacecraft to a given launch was used as a figure of merit. When compared to chemical propulsion ammonia resistojets, ion, Hall, and pulsed plasma thrusters allowed an additional spacecraft per launch Typical orbit insertion and de-orbit times were found to range from a few days to a few months.

  9. Impact orbits of the asteroid 2009 FJ with the Earth

    NASA Astrophysics Data System (ADS)

    Wlodarczyk, Ireneusz

    2012-07-01

    We show how to calculate the impact orbits of dangerous asteroids using the freely available the OrbFit software, and compare our results with impact orbits calculated using Sitarski's independent software (Sitarski, 1999; 2000; 2006). The new method is tested on asteroid 2009 FJ. Using the OrbFit package to integrate alternate orbits along the line of variation (Milani et al., 2002; 2005a; 2005b), we identify impact orbits and can plot paths of risk for the Earth or any other body in the Solar System. We present the orbital elements of asteroid 2009 FJ and its ephemerides, along with uncertainties, for the next 100 years. This paper continues a long-term research program on impact solutions for asteroids (Wlodarczyk, 2007; 2008; 2009).

  10. The Space Debris Environment for the ISS Orbit

    NASA Technical Reports Server (NTRS)

    Theall, Jeff; Liou, Jer-Chyi; Matney, Mark; Kessler, Don

    2001-01-01

    With thirty-five planned missions over the next five years, the International Space Station (ISS) will be the focus for manned space activity. At least 6 different vehicles will transport crew and supplies to and from the nominally 400 km, 51.6 degree orbit. When completed, the ISS will be the largest space structure ever assembled and hence the largest target for space debris. Recent work at the Johnson Space Center has focused on updating the existing space debris models. The Orbital Debris Engineering Model, has been restructured to take advantage of state of the art desktop computing capability and revised with recent measurements from Haystack and Goldstone radars, additional analysis of LDEF and STS impacts, and the most recent SSN catalog. The new model also contains the capability to extrapolate the current environment in time to the year 2030. A revised meteoroid model based on the work of Divine has also been developed, and is called the JSC Meteoroid Model. The new model defines flux on the target per unit angle per unit speed, and for Earth orbit, includes the meteor showers. This paper quantifies the space debris environment for the ISS orbit from natural and anthropogenic sources. Particle flux and velocity distributions as functions of size and angle are be given for particles 10 microns and larger for altitudes from 350 to 450 km. The environment is projected forward in time until 2030.

  11. Spacecraft Orbits for Earth/Mars-Lander Radio Relay

    NASA Technical Reports Server (NTRS)

    Noreen, Gary; Diehl, Roger; Neelon, Joseph

    2004-01-01

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

  12. A Comparison of Atomic Oxygen Degradation in Low Earth Orbit and in a Plasma Etcher

    NASA Technical Reports Server (NTRS)

    Townsend, Jacqueline A.; Park, Gloria

    1997-01-01

    In low Earth orbit (LEO) significant degradation of certain materials occurs from exposure to atomic oxygen (AO). Orbital opportunities to study this degradation for specific materials are limited and expensive. While plasma etchers are commonly used in ground-based studies because of their low cost and convenience, the environment produced in an etcher chamber differs greatly from the LEO environment. Because of the differences in environment, the validity of using etcher data has remained an open question. In this paper, degradation data for 22 materials from the orbital experiment Evaluation of Oxygen Interaction with Materials (EOIM-3) are compared with data from EOIM-3 control specimens exposed in a typical plasma etcher. This comparison indicates that, when carefully considered, plasma etcher results can produce order-of-magnitude estimates of orbital degradation. This allows the etcher to be used to screen unacceptable materials from further, more expensive tests.

  13. Averaging on Earth-Crossing Orbits

    NASA Astrophysics Data System (ADS)

    Gronchi, G. F.; Milani, A.

    The orbits of planet-crossing asteroids (and comets) can undergo close approaches and collisions with some major planet. This introduces a singularity in the N-body Hamiltonian, and the averaging of the equations of motion, traditionally used to compute secular perturbations, is undefined. We show that it is possible to define in a rigorous way some generalised averaged equations of motion, in such a way that the generalised solutions are unique and piecewise smooth. This is obtained, both in the planar and in the three-dimensional case, by means of the method of extraction of the singularities by Kantorovich. The modified distance used to approximate the singularity is the one used by Wetherill in his method to compute probability of collision. Some examples of averaged dynamics have been computed; a systematic exploration of the averaged phase space to locate the secular resonances should be the next step. `Alice sighed wearily. ``I think you might do something better with the time'' she said, ``than waste it asking riddles with no answers'' (Alice in Wonderland, L. Carroll)

  14. A Survey Of Earth-Moon Libration Orbits: Stationkeeping Strategies And Intra-Orbit Transfers

    NASA Technical Reports Server (NTRS)

    Folta, David; Vaughn, Frank

    2004-01-01

    Cislunar space is a readily accessible region that may well develop into a prime staging area in the effort to colonize space near Earth or to colonize the Moon. While there have been statements made by various NASA programs regarding placement of resources in orbit about the Earth-Moon Lagrangian locations, there is no survey of the total cost associated with attaining and maintaining these unique orbits in an operational fashion. Transfer trajectories between these orbits required for assembly, servicing, and positioning of these resources have not been extensively investigated. These orbits are dynamically similar to those used for the Sun-Earth missions, but differences in governing gravitational ratios and perturbation sources result in unique characteristics. We implement numerical computations using high fidelity models and linear and nonlinear targeting techniques to compute the various maneuver (Delta)V and temporal costs associated with orbits about each of the Earth-Moon Lagrangian locations (L1, L2, L3, L4, and L5). From a dynamical system standpoint, we speak to the nature of these orbits and their stability. We address the cost of transfers between each pair of Lagrangian locations.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  16. Low earth orbit satellite/terrestrial mobile service compatibility

    NASA Technical Reports Server (NTRS)

    Sheriff, R. E.; Gardiner, J. G.

    1993-01-01

    Digital cellular mobile 'second generation' systems are now gradually being introduced into service; one such example is GSM, which will provide a digital voice and data service throughout Europe. Total coverage is not expected to be achieved until the mid '90's, which has resulted in several proposals for the integration of GSM with a geostationary satellite service. Unfortunately, because terrestrial and space systems have been designed to optimize their performance for their particular environment, integration between a satellite and terrestrial system is unlikely to develop further than the satellite providing a back-up service. This lack of system compatibility is now being addressed by system designers of third generation systems. The next generation of mobile systems, referred to as FPLMTS (future public land mobile telecommunication systems) by CCIR and UMTS (universal mobile telecommunication system) in European research programs, are intended to provide inexpensive, hand-held terminals that can operate in either satellite, cellular, or cordless environments. This poses several challenges for system designers, not least in terms of the choice of multiple access technique and power requirements. Satellite mobile services have been dominated by the geostationary orbital type. Recently, however, a number of low earth orbit configurations have been proposed, for example Iridium. These systems are likely to be fully operational by the turn of the century, in time for the implementation of FPLMTS. The developments in LEO mobile satellite service technology were recognized at WARC-92 with the allocation of specific frequency bands for 'big' LEO's, as well as a frequency allocation for FPLMTS which included a specific satellite allocation. When considering integrating a space service into the terrestrial network, LEO's certainly appear to have their attractions: they can provide global coverage, the round trip delay is of the order of tens of milliseconds, and

  17. Instability of the Current Space Debris Population in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Maniwa, Kazuaki; Hanada, Toshiya; Kawamoto, Satomi

    Since the launch of Sputnik, orbital debris population continues to increase due to ongoing space activities, on-orbit explosions, and accidental collisions. In the future, it is expected that a great deal of fragments will be created by explosions and collisions. Thus, the number of space debris may increase exponentially (Kessler Syndrome). This paper analyzes the Kessler Syndrome using the Low Earth Orbital Debris Environmental Evolutionary Model (LEODEEM) developed at Kyushu University with collaboration from JAXA. The purpose of the study aims at understanding the issues related to space environment conservation. The results provide effective conditions of Active Debris Removal which is one of the space debris mitigation procedures.

  18. Future radiation measurements in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    1993-01-01

    The first Long Duration Exposure Facility (LDEF) mission has demonstrated the value of the LDEF concept for deep surveys of the space radiation environment. The kinds of measurements that could be done on a second LDEF mission are discussed. Ideas are discussed for experiments which: (1) capitalize on the discoveries from LDEF 1; (2) take advantage of LDEF's unique capabilities; and (3) extend the investigations begun on LDEF 1. These ideas have been gleaned from investigators on LDEF 1 and others interested in the space radiation environment. They include new approaches to the investigation of Be-7 that was discovered on LDEF 1, concepts to obtain further information on the ionic charge state of cosmic rays and other energetic particles in space and other ideas to extend the investigations begun on LDEF 1.

  19. A Geostationary Earth Orbit Satellite Model Using Easy Java Simulation

    ERIC Educational Resources Information Center

    Wee, Loo Kang; Goh, Giam Hwee

    2013-01-01

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

  20. Approach to rapid mission design and planning. [earth orbit missions

    NASA Technical Reports Server (NTRS)

    Green, W. G.; Matthys, V. J.

    1973-01-01

    Methods and techniques are described for implementation in automated computer systems to assess parametric data, capabilities, requirements and constraints for planning earth orbit missions. Mission planning and design procedures are defined using two types of typical missions as examples. These missions were the high energy Astronomical Observatory Satellite missions, and Small Applications Technology Satellite missions.

  1. Dose in critical body organs in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Cucinotta, F.

    1984-01-01

    Human exposure to trapped radiations in low Earth orbit (LEO) are evaluated on the basis of a simple approximation of the human geometry for spherical shell shields of varying thickness. A data base is presented that may be used to make preliminary assessment of the impact of radiation exposure constraints on human performance. A sample impact assessment is discussed.

  2. From Earth to orbit. [assessment of transportation options

    NASA Technical Reports Server (NTRS)

    Gavin, Joseph G., Jr.; Blond, Edmund; Brill, Yvonne C.; Budiansky, Bernard; Cooper, Robert S.; Demisch, Wolfgang H.; Hawk, Clark W.; Kerrebrock, Jack L.; Lichtenberg, Byron K.; Mager, Arthur

    1992-01-01

    Within this document, the National Research Council (NRC) assesses the requirements, benefits, technological feasibility, and roles of Earth-to-orbit transportation options that could be developed in support of the national space program. Among the topics covered are launch vehicles and infrastructure, propulsion, and technology.

  3. Can Sunlight Shift the Earth onto a Different Orbit?

    ERIC Educational Resources Information Center

    Esposito, S.

    2011-01-01

    This article comes from a question asked by a student of mine: if the Sun radiates energy in the form of electromagnetic waves, could they shift the Earth from its current orbit on a suitable timescale? The answer to such a question is apparently obvious and trivial. Nevertheless, it requires an instructive reasoning and interesting estimates of…

  4. Solar sail orbits at the Earth-Moon libration points

    NASA Astrophysics Data System (ADS)

    Simo, Jules; McInnes, Colin R.

    2009-12-01

    Solar sail technology offer new capabilities for the analysis and design of space missions. This new concept promises to be useful in overcoming the challenges of moving throughout the solar system. In this paper, novel families of highly non-Keplerian orbits for solar sail spacecraft at linear order are investigated in the Earth-Moon circular restricted three-body problem, where the third body is a solar sail. In particular, periodic orbits near the collinear libration points in the Earth-Moon system will be explored along with their applications. The dynamics are completely different from the Earth-Sun system in that the sun line direction constantly changes in the rotating frame but rotates once per synodic lunar month. Using an approximate, first-order analytical solution to the nonlinear nonautonomous ordinary differential equations, periodic orbits can be constructed that are displaced above the plane of the restricted three-body system. This new family of orbits have the property of ensuring visibility of both the lunar far-side and the equatorial regions of the Earth, and can enable new ways of performing lunar telecommunications.

  5. Microlensing planet detection via geosynchronous and low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Mogavero, F.; Beaulieu, J. P.

    2016-01-01

    Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale tE, which prevents mass and distance of the lens to be univocally determined. It has been shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events (tE ≈ 20 days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, tE ≈ 1 day, when dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite on even shorter timescales, tE ≈ 0.1 days. A Fisher matrix analysis is employed to predict how the 1-σ error on parallax depends on tE and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending, and in the case of the low orbit, the Earth's umbra.

  6. Design of an unmanned, reusable vehicle to de-orbit debris in Earth orbit

    NASA Technical Reports Server (NTRS)

    Aziz, Shahed; Cunningham, Timothy W.; Moore-Mccassey, Michelle

    1990-01-01

    The space debris problem is becoming more important because as orbital missions increase, the amount of debris increases. It was the design team's objective to present alternative designs and a problem solution for a deorbiting vehicle that will alleviate the problem by reducing the amount of large debris in earth orbit. The design team was asked to design a reusable, unmanned vehicle to de-orbit debris in earth orbit. The design team will also construct a model to demonstrate the system configuration and key operating features. The alternative designs for the unmanned, reusable vehicle were developed in three stages: selection of project requirements and success criteria, formulation of a specification list, and the creation of alternatives that would satisfy the standards set forth by the design team and their sponsor. The design team selected a Chain and Bar Shot method for deorbiting debris in earth orbit. The De-orbiting Vehicle (DOV) uses the NASA Orbital Maneuvering Vehicle (OMV) as the propulsion and command modules with the deorbiting module attached to the front.

  7. ISS Charging Hazards and Low Earth Orbit Space Weather Effects

    NASA Technical Reports Server (NTRS)

    Minow, Joseph; Parker, L.; Coffey, V.; Wright K.; Koontz, S.; Edwards, D.

    2008-01-01

    Current collection by high voltage solar arrays on the International Space Station (ISS) drives the vehicle to negative floating potentials in the low Earth orbit daytime plasma environment. Pre-flight predictions of ISS floating potentials Phi greater than |-100 V| suggested a risk for degradation of dielectric thermal control coatings on surfaces in the U.S. sector due to arcing and an electrical shock hazard to astronauts during extravehicular activity (EVA). However, hazard studies conducted by the ISS program have demonstrated that the thermal control material degradation risk is effectively mitigated during the lifetime of the ISS vehicle by a sufficiently large ion collection area present on the vehicle to balance current collection by the solar arrays. To date, crew risk during EVA has been mitigated by operating one of two plasma contactors during EVA to control the vehicle potential within Phi less than or equal to |-40 V| with a backup process requiring reorientation of the solar arrays into a configuration which places the current collection surfaces into wake. This operation minimizes current collection by the solar arrays should the plasma contactors fail. This paper presents an analysis of F-region electron density and temperature variations at low and midlatitudes generated by space weather events to determine what range of conditions represent charging threats to ISS. We first use historical ionospheric plasma measurements from spacecraft operating at altitudes relevant to the 51.6 degree inclination ISS orbit to provide an extensive database of F-region plasma conditions over a variety of solar cycle conditions. Then, the statistical results from the historical data are compared to more recent in-situ measurements from the Floating Potential Measurement Unit (FPMU) operating on ISS in a campaign mode since its installation in August, 2006.

  8. Orbit Determination Accuracy for Comets on Earth-Impacting Trajectories

    NASA Technical Reports Server (NTRS)

    Kay-Bunnell, Linda

    2004-01-01

    The results presented show the level of orbit determination accuracy obtainable for long-period comets discovered approximately one year before collision with Earth. Preliminary orbits are determined from simulated observations using Gauss' method. Additional measurements are incorporated to improve the solution through the use of a Kalman filter, and include non-gravitational perturbations due to outgassing. Comparisons between observatories in several different circular heliocentric orbits show that observatories in orbits with radii less than 1 AU result in increased orbit determination accuracy for short tracking durations due to increased parallax per unit time. However, an observatory at 1 AU will perform similarly if the tracking duration is increased, and accuracy is significantly improved if additional observatories are positioned at the Sun-Earth Lagrange points L3, L4, or L5. A single observatory at 1 AU capable of both optical and range measurements yields the highest orbit determination accuracy in the shortest amount of time when compared to other systems of observatories.

  9. PRODUCTION OF NEAR-EARTH ASTEROIDS ON RETROGRADE ORBITS

    SciTech Connect

    Greenstreet, S.; Gladman, B.; Ngo, H.; Granvik, M.; Larson, S.

    2012-04-20

    While computing an improved near-Earth object (NEO) steady-state orbital distribution model, we discovered in the numerical integrations the unexpected production of retrograde orbits for asteroids that had originally exited from the accepted main-belt source regions. Our model indicates that {approx}0.1% (a factor of two uncertainty) of the steady-state NEO population (perihelion q < 1.3 AU) is on retrograde orbits. These rare outcomes typically happen when asteroid orbits flip to a retrograde configuration while in the 3:1 mean-motion resonance with Jupiter and then live for {approx}0.001 to 100 Myr. The model predicts, given the estimated near-Earth asteroid (NEA) population, that a few retrograde 0.1-1 km NEAs should exist. Currently, there are two known MPC NEOs with asteroidal designations on retrograde orbits which we therefore claim could be escaped asteroids instead of devolatilized comets. This retrograde NEA population may also answer a long-standing question in the meteoritical literature regarding the origin of high-strength, high-velocity meteoroids on retrograde orbits.

  10. Orbital Feshbach Resonance in Alkali-Earth Atoms.

    PubMed

    Zhang, Ren; Cheng, Yanting; Zhai, Hui; Zhang, Peng

    2015-09-25

    For a mixture of alkali-earth atomic gas in the long-lived excited state ^{3}P_{0} and the ground state ^{1}S_{0}, in addition to nuclear spin, another "orbital" index is introduced to distinguish these two internal states. In this Letter we propose a mechanism to induce Feshbach resonance between two atoms with different orbital and nuclear spin quantum numbers. Two essential ingredients are the interorbital spin-exchange process and orbital dependence of the Landé g factors. Here the orbital degrees of freedom plays a similar role as the electron spin degree of freedom in magnetic Feshbach resonance in alkali-metal atoms. This resonance is particularly accessible for the ^{173}Yb system. The BCS-BEC crossover in this system requires two fermion pairing order parameters, and displays a significant difference compared to that in an alkali-metal system. PMID:26451561

  11. Orbital Feshbach Resonance in Alkali-Earth Atoms

    NASA Astrophysics Data System (ADS)

    Zhang, Ren; Cheng, Yanting; Zhai, Hui; Zhang, Peng

    2015-09-01

    For a mixture of alkali-earth atomic gas in the long-lived excited state 3P0 and the ground state 1S0, in addition to nuclear spin, another "orbital" index is introduced to distinguish these two internal states. In this Letter we propose a mechanism to induce Feshbach resonance between two atoms with different orbital and nuclear spin quantum numbers. Two essential ingredients are the interorbital spin-exchange process and orbital dependence of the Landé g factors. Here the orbital degrees of freedom plays a similar role as the electron spin degree of freedom in magnetic Feshbach resonance in alkali-metal atoms. This resonance is particularly accessible for the 173Yb system. The BCS-BEC crossover in this system requires two fermion pairing order parameters, and displays a significant difference compared to that in an alkali-metal system.

  12. Monitoring objects orbiting earth using satellite-based telescopes

    DOEpatents

    Olivier, Scot S.; Pertica, Alexander J.; Riot, Vincent J.; De Vries, Willem H.; Bauman, Brian J.; Nikolaev, Sergei; Henderson, John R.; Phillion, Donald W.

    2015-06-30

    An ephemeris refinement system includes satellites with imaging devices in earth orbit to make observations of space-based objects ("target objects") and a ground-based controller that controls the scheduling of the satellites to make the observations of the target objects and refines orbital models of the target objects. The ground-based controller determines when the target objects of interest will be near enough to a satellite for that satellite to collect an image of the target object based on an initial orbital model for the target objects. The ground-based controller directs the schedules to be uploaded to the satellites, and the satellites make observations as scheduled and download the observations to the ground-based controller. The ground-based controller then refines the initial orbital models of the target objects based on the locations of the target objects that are derived from the observations.

  13. Precise halo orbit design and optimal transfer to halo orbits from earth using differential evolution

    NASA Astrophysics Data System (ADS)

    Nath, Pranav; Ramanan, R. V.

    2016-01-01

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

  14. Marking Tests to Certify Part Identification Processes for Use in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Roxby, D. L.

    2015-01-01

    The primary purpose for the MISSE marking tests was to define Data Matrix symbol marking processes that will remain readable after exposure to Low Earth Orbit environments. A wide range of different Data Matrix symbol marking processes and materials, including some still under development, were evaluated. The samples flown on MISSE 1 and 2 were in orbit for 3 years and 348 days, MISSE 3 and 4 were in orbit for 1 year and 15 days, MISSE 6 was in orbit for 1 year and 130 days, and MISSE 8 was in orbit for 2 years and 55 days. The initial MISSE marking tests clearly reflected that intrusive marking processes can be successfully used for this purpose. All of the intrusive marking processes tested exceeded program expectations and met 100 percent of the principle investigators objectives. However, subsequent tests demonstrated that some additive marking processes will also satisfy the requirements. This was an unexpected result.

  15. Unmanned servicing of Earth observation systems in sunsynchronous orbits

    NASA Astrophysics Data System (ADS)

    Sliney, Jack; Robertson, Bill; Misencik, Tom; Lee, Jeannie

    This paper addresses the feasibility of servicing or reboosting Earth observation spacecraft that are in or near sunsynchronous orbits through the use of an unmanned servicing vehicle. The term sunsynchronous (SS) as used here pertains to any retrograde orbit which exhibits a nodal regression rate of 360° per year, so that the orbit plane maintains a constant angle to the sun. The paper addresses both quantitatively and qualitatively how future Earth observation systems in inclinations between 96 and 100° may be periodically serviced using a transfer vehicle and other components needed to carry out the support mission. Two operational concepts are considered for the employment of the transfer vehicle. In one case, the vehicle is based at a Space Based Support Platform (SBSP) which remains at a lower altitude and higher inclination than the assets to be serviced. Consideration is also given to servicing from a transfer vehicle which is a free flyer (i.e. not based at an SBSP). The design requirements of the servicer are discussed quantitiatively and sample calculations of ΔV and propellant expenditure are given. Consideration is given to the NASA developed Orbital Maneuvering Vehicle (OMV), and other transfer vehicles which use electrical or other advanced propulsion. In addition, a quantitative assessment is made of the subsystem redundancy requirements in the design for an Earth observation satellite that is periodically serviced as compared with design requirements for an unserviceable spacecraft. The benefits of servicing with respect to Pre-planned Product Improvements (P 3I) are discussed.

  16. Analysis on high-altitude earth Orbit Satellite Determination

    NASA Astrophysics Data System (ADS)

    He, J.; Hou, Y. W.; Yang, L.

    2016-02-01

    The difference is introduced between approx circular apogee orbit and approx circular perigee one by error transmitting at first. Then the characteristic of secant compensation is analysed when radar tracking object with high elevation. And two kinds of orbit force be pressed to, their perturbation influence and their earth-core angles are explained. And then the series of emulation results are shown including error data emulated with Monte Carlo method, the influence of the velocity increment from the ejecting force of spring while satellite-rocket separating and their perturbation influence and the length of influence of the data arc. Then decision analysis of Wald method and Bayesian statistics rule and the results from the two rule are introduced. So the suitable orbit determination decision is put forward from the decision method. Finally the result is tested reasonable and feasible via the real data. In the end it is useful to reference to make orbit decision in short injection of circular orbit far from the earth for calculating concurrently precise and timely.

  17. Low Earth Orbit Raider (LER) winged air launch vehicle concept

    NASA Technical Reports Server (NTRS)

    Feaux, Karl; Jordan, William; Killough, Graham; Miller, Robert; Plunk, Vonn

    1989-01-01

    The need to launch small payloads into low earth orbit has increased dramatically during the past several years. The Low Earth orbit Raider (LER) is an answer to this need. The LER is an air-launched, winged vehicle designed to carry a 1500 pound payload into a 250 nautical mile orbit. The LER is launched from the back of a 747-100B at 35,000 feet and a Mach number of 0.8. Three staged solid propellant motors offer safe ground and flight handling, reliable operation, and decreased fabrication cost. The wing provides lift for 747 separation and during the first stage burn. Also, aerodynamic controls are provided to simplify first stage maneuvers. The air-launch concept offers many advantages to the consumer compared to conventional methods. Launching at 35,000 feet lowers atmospheric drag and other loads on the vehicle considerably. Since the 747 is a mobile launch pad, flexibility in orbit selection and launch time is unparalleled. Even polar orbits are accessible with a decreased payload. Most importantly, the LER launch service can come to the customer, satellites and experiments need not be transported to ground based launch facilities. The LER is designed to offer increased consumer freedom at a lower cost over existing launch systems. Simplistic design emphasizing reliability at low cost allows for the light payloads of the LER.

  18. Simplified Orbit Determination Algorithm for Low Earth Orbit Satellites Using Spaceborne Gps Navigation Sensor

    NASA Astrophysics Data System (ADS)

    Tukaram Aghav, Sandip; Achyut Gangal, Shashikala

    2014-06-01

    In this paper, the main work is focused on designing and simplifying the orbit determination algorithm which will be used for Low Earth Orbit (LEO) navigation. The various data processing algorithms, state estimation algorithms and modeling forces were studied in detail, and simplified algorithm is selected to reduce hardware burden and computational cost. This is done by using raw navigation solution provided by GPS Navigation sensor. A fixed step-size Runge-Kutta 4th order numerical integration method is selected for orbit propagation. Both, the least square and Extended Kalman Filter (EKF) orbit estimation algorithms are developed and the results of the same are compared with each other. EKF algorithm converges faster than least square algorithm. EKF algorithm satisfies the criterions of low computation burden which is required for autonomous orbit determination. Simple static force models also feasible to reduce the hardware burden and computational cost.

  19. Contributions of Satellite Laser Ranging to the Precise Orbit Determination of Low Earth Orbiters

    NASA Astrophysics Data System (ADS)

    Wirnsberger, H.; Krauss, S.; Baur, O.

    2014-11-01

    Space-based monitoring and modeling of the system Earth requires precise knowledge of the orbits of artificial satellites. In this framework, since decades Satellite Laser Ranging (SLR) contributes with high measurement accuracy and robust tracking data to precise orbit determination. One essential role of SLR tracking is the external validation of orbit solutions derived from Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS). This valuable task of external validation is performed by the comparison of computed ranges based on orbit solutions and unambiguous SLR tracking data (observed ranges). Apart from validation, extension of the existing SLR network by passive antennas in combination with multistatic observations provides improvements in orbit determination processes with the background of sparse tracking data. Conceptually, these multistatic observations refer to the tracking of spacecraft from an active SLR-station and the detection of the diffuse reflected photons from the spacecraft at one or more passive stations.

  20. Microwave antenna temperature of the earth from geostationary orbit

    NASA Technical Reports Server (NTRS)

    Njoku, E. G.; Smith, E. K.

    1985-01-01

    The microwave antenna temperature of the earth has been computed for the case of a communication satellite antenna viewing the earth from geostationary orbit. An earth-coverage beam is assumed and detailed computations are performed to account for varying land-ocean fractions within the field of view. Emission characteristics of the earth's atmosphere and surface are used with an accurate radiative transfer program to compute observed brightness temperatures. Values of 250 to 290 K commonly used for antenna temperature in satellite communication noise calculations are found to be over-conservative estimates, with more realistic values lying in the 60-240 K range depending on frequency and subsatellite longitude. These values also depend on assumptions concerning antenna beam coverage. Variations in atmospheric and surface conditions, and variations in antenna beam shape (as distinct from coverage), affect the computed results by less than about 10 K.

  1. Effects of DeOrbitSail as applied to Lifetime predictions of Low Earth Orbit Satellites

    NASA Astrophysics Data System (ADS)

    Afful, Andoh; Opperman, Ben; Steyn, Herman

    2016-07-01

    Orbit lifetime prediction is an important component of satellite mission design and post-launch space operations. Throughout its lifetime in space, a spacecraft is exposed to risk of collision with orbital debris or operational satellites. This risk is especially high within the Low Earth Orbit (LEO) region where the highest density of space debris is accumulated. This paper investigates orbital decay of some LEO micro-satellites and accelerating orbit decay by using a deorbitsail. The Semi-Analytical Liu Theory (SALT) and the Satellite Toolkit was employed to determine the mean elements and expressions for the time rates of change. Test cases of observed decayed satellites (Iridium-85 and Starshine-1) are used to evaluate the predicted theory. Results for the test cases indicated that the theory fitted observational data well within acceptable limits. Orbit decay progress of the SUNSAT micro-satellite was analysed using relevant orbital parameters derived from historic Two Line Element (TLE) sets and comparing with decay and lifetime prediction models. This paper also explored the deorbit date and time for a 1U CubeSat (ZACUBE-01). The use of solar sails as devices to speed up the deorbiting of LEO satellites is considered. In a drag sail mode, the deorbitsail technique significantly increases the effective cross-sectional area of a satellite, subsequently increasing atmospheric drag and accelerating orbit decay. The concept proposed in this study introduced a very useful technique of orbit decay as well as deorbiting of spacecraft.

  2. Earth Trek...Explore Your Environment.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC. Office of Public Affairs.

    This booklet for children emphasizes the exploration and protection of the environment. An introduction discusses the interaction between humankind and the environment, emphasizing that the earth is a closed system. Chapter 1, "Mission: Protect the Water," addresses human dependence on water, water pollution, and water treatment. Chapter 2,…

  3. Low earth orbit environmental effects on the Space Station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, H. K.

    1988-01-01

    A summary of the low earth orbital environment, its impact on the photovoltaic power systems of the Space Station and the solutions implemented to resolve the environmental concerns or issues are described. Low earth orbital environment (LEO) presents several concerns to the photovoltaic power systems of the Space Station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the Space Station with the desired life are also summarized.

  4. Low Earth orbit environmental effects on the space station photovoltaic power generation systems

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.

    1987-01-01

    A summary of the Low Earth Orbital Environment, its impact on the Photovoltaic Power systems of the space station and the solutions implemented to resolve the environmental concerns or issues are described. Low Earth Orbital Environment (LEO) presents several concerns to the Photovoltaic power systems of the space station. These concerns include atomic oxygen interaction with the polymeric substrate of the solar arrays, ionized environment effects on the array operating voltage, the effects of the meteoroids and debris impacts and penetration through the different layers of the solar cells and their circuits, and the high energy particle and radiation effects on the overall solar array performance. Potential solutions to some of the degrading environmental interactions that will provide the photovoltaic power system of the space station with the desired life are also summarized.

  5. Mechanical properties of silicate glasses exposed to a low-Earth orbit

    NASA Technical Reports Server (NTRS)

    Wiedlocher, David E.; Tucker, Dennis S.; Nichols, Ron; Kinser, Donald L.

    1992-01-01

    The effects of a 5.8 year exposure to low earth orbit environment upon the mechanical properties of commercial optical fused silica, low iron soda-lime-silica, Pyrex 7740, Vycor 7913, BK-7, and the glass ceramic Zerodur were examined. Mechanical testing employed the ASTM-F-394 piston on 3-ball method in a liquid nitrogen environment. Samples were exposed on the Long Duration Exposure Facility (LDEF) in two locations. Impacts were observed on all specimens except Vycor. Weibull analysis as well as a standard statistical evaluation were conducted. The Weibull analysis revealed no differences between control samples and the two exposed samples. We thus concluded that radiation components of the Earth orbital environment did not degrade the mechanical strength of the samples examined within the limits of experimental error. The upper bound of strength degradation for meteorite impacted samples based upon statistical analysis and observation was 50 percent.

  6. Optical Observations of the Orbital Debris Environment at NASA

    NASA Technical Reports Server (NTRS)

    Africano, John L.; Stansbery, Eugene G.; McKay, Gordon A. (Technical Monitor)

    1999-01-01

    To gain a better understanding of the LEO and MEO (low and middle earth orbit) optical orbital debris environments, especially in the important, but difficult to track one to ten centimeter size range, NASA Johnson Space Center (JSC) has built a zenith-staring Liquid Mirror Telescope (LMT) near Cloudcroft, NM. The mirror of the LMT consists of a three-meter diameter parabolic dish containing several gallons of mercury that is spun at a rate of ten revolutions per minute. A disadvantage of the LMT is its inability to point in any direction other than the zenith. However, this is not a major limitation for statistical sampling of the LEO and MEO orbital debris population. While the LMT is used for the characterization of the LEO and MEO orbital debris environments, its inability to point off zenith limits its utility for the GEO environment where objects are concentrated over the equator. To gain a better understanding of the GEO debris environment, NASA JSC has built a CCD Debris Telescope (CDT). The CDT is a 12.5-inch aperture Schmidt portable telescope with automated pointing capability. The CDT is presently co-located with the LMT. The CDT can see down to 17.1 magnitude in a 30 second exposure with a 1.5 degree field of view. This corresponds to a ten percent reflective, 0.8-meter diameter object at geosynchronous altitude. Both telescopes are used every clear night. We present results from 3 years of observations from the LMT and preliminary results from the CDT.

  7. Mars environment and magnetic orbiter model payload

    NASA Astrophysics Data System (ADS)

    Langlais, B.; Leblanc, F.; Fouchet, T.; Barabash, S.; Breuer, D.; Chassefière, E.; Coates, A.; Dehant, V.; Forget, F.; Lammer, H.; Lewis, S.; Lopez-Valverde, M.; Mandea, M.; Menvielle, M.; Pais, A.; Paetzold, M.; Read, P.; Sotin, C.; Tarits, P.; Vennerstrom, S.; Branduardi-Raymont, G.; Cremonese, G.; Merayo, J. G. M.; Ott, T.; Rème, H.; Trotignon, J. G.; Walhund, J. E.

    2009-03-01

    Mars Environment and Magnetic Orbiter was proposed as an answer to the Cosmic Vision Call of Opportunity as a M-class mission. The MEMO mission is designed to study the strong interconnections between the planetary interior, atmosphere and solar conditions essential to understand planetary evolution, the appearance of life and its sustainability. MEMO provides a high-resolution, complete, mapping of the magnetic field (below an altitude of about 250 km), with an yet unachieved full global coverage. This is combined with an in situ characterization of the high atmosphere and remote sensing of the middle and lower atmospheres, with an unmatched accuracy. These measurements are completed by an improved detection of the gravity field signatures associated with carbon dioxide cycle and to the tidal deformation. In addition the solar wind, solar EUV/UV and energetic particle fluxes are simultaneously and continuously monitored. The challenging scientific objectives of the MEMO mission proposal are fulfilled with the appropriate scientific instruments and orbit strategy. MEMO is composed of a main platform, placed on a elliptical (130 × 1,000 km), non polar (77° inclination) orbit, and of an independent, higher apoapsis (10,000 km) and low periapsis (300 km) micro-satellite. These orbital parameters are designed so that the scientific return of MEMO is maximized, in terms of measurement altitude, local time, season and geographical coverage. MEMO carry several suites of instruments, made of an ‘exospheric-upper atmosphere’ package, a ‘magnetic field’ package, and a ‘low-middle atmosphere’ package. Nominal mission duration is one Martian year.

  8. Polyhedral representation of invariant manifolds applied to orbit transfers in the Earth-Moon system

    NASA Astrophysics Data System (ADS)

    Pontani, Mauro; Teofilatto, Paolo

    2016-02-01

    Recently, manifold dynamics has assumed an increasing relevance for analysis and design of low-energy missions, both in the Earth-Moon system and in alternative multibody environments. This work proposes and describes an intuitive polyhedral interpolative approach for each state component associated with manifold trajectories, both in two and in three dimensions. An adequate grid of data, coming from the numerical propagation of a finite number of manifold trajectories, is employed. Accuracy of this representation is evaluated with reference to the invariant manifolds associated with a two-dimensional Lyapunov orbit and a three-dimensional Halo orbit, and is proven to be satisfactory, with the exclusion of limited regions of the manifolds. As a first, preliminary application, the polyhedral interpolation technique allows identifying the orbits in the proximity of the interior collinear libration point as either asymptotic, transit, or bouncing trajectories. Then, two applications to orbital maneuvering are addressed. First, the globally optimal two-impulse transfer between a specified low Earth orbit and a Lyapunov orbit (through its stable manifold) is determined. Second, the minimum-time low-thrust transfer from the same terminal orbits is found using again the stable manifold. These applications prove the effectiveness of the polyhedral interpolative technique and represent the premise for its application also to different problems involving invariant manifold dynamics.

  9. Atomic Oxygen Protection of Materials in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Demko, Rikako

    2002-01-01

    Spacecraft polymeric materials as well as polymer-matrix carbon-fiber composites can be significantly eroded as a result of exposure to atomic oxygen in low Earth orbit (LEO). Several new materials now exist, as well as modifications to conventionally used materials, that provide much more resistance to atomic oxygen attack than conventional hydrocarbon polymers. Protective coatings have also been developed which are resistant to atomic oxygen attack and provide protection of underlying materials. However, in actual spacecraft applications, the configuration, choice of materials, surface characteristics and functional requirements of quasi-durable materials or protective coatings can have great impact on the resulting performance and durability. Atomic oxygen degradation phenomena occurring on past and existing spacecraft will be presented. Issues and considerations involved in providing atomic oxygen protection for materials used on spacecraft in low Earth orbit will be addressed. Analysis of in-space results to determine the causes of successes and failures of atomic oxygen protective coatings is presented.

  10. Relativistic effects for low Earth orbit satellites using GPS

    NASA Astrophysics Data System (ADS)

    Spallicci, A.; Jimenez, C.; Prisco, G.; Ashby, N.

    1992-06-01

    The relativistic corrections for a low Earth orbit satellite are evaluated. The GPS (Global Positioning System) satellite clock rate is slowed before launch by 4.465 x 10(exp -10), called the 'factory offset', for time dilation and gravitational frequency shift. This offset cancels the main constant relativistic effects for terrestrial users, which in order to operate in coordinate time have only to process the GPS orbital eccentricities, a sinusoidal function whose peaks are in the order of tens of ns, and the Sagnac effect. For a space user the situation greatly differs, because a large part of the relativistic effects are still present due to the high velocity of the satellite and its location in the Earth gravitational field. Past tests and proposals for future measurements with GPS--perigee advance, Shapiro time delay, preferred frame independence, Lense Thirring effect, light bending and gravitational waves--are reviewed.

  11. Mechanical failure probability of glasses in Earth orbit

    NASA Technical Reports Server (NTRS)

    Kinser, Donald L.; Wiedlocher, David E.

    1992-01-01

    Results of five years of earth-orbital exposure on mechanical properties of glasses indicate that radiation effects on mechanical properties of glasses, for the glasses examined, are less than the probable error of measurement. During the 5 year exposure, seven micrometeorite or space debris impacts occurred on the samples examined. These impacts were located in locations which were not subjected to effective mechanical testing, hence limited information on their influence upon mechanical strength was obtained. Combination of these results with micrometeorite and space debris impact frequency obtained by other experiments permits estimates of the failure probability of glasses exposed to mechanical loading under earth-orbit conditions. This probabilistic failure prediction is described and illustrated with examples.

  12. Lageos orbit decay due to infrared radiation from Earth

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    1987-01-01

    Infrared radiation from the Earth may be the principal reason for the decay of Lageos' orbit. The radiation heats up the laser retroreflectors embedded in Lageos' aluminum surface. This creates a north-south temperature gradient on the satellite. The gradient in turn causes a force to be exerted on Lageos because of recoil from photons leaving its surface. The delayed heating of the retroreflectors due to their thermal inertia gives the force a net along-track component which always acts like drag. A simple thermal model for the retroreflectors indicates that this thermal drag accounts for about half the observed average along-track acceleration of -3.3 x 10 to the -10 power m/sec squared. The contribution from the aluminum surface to this effect is negligible. The infrared effect cannot explain the large observed fluctuations in drag which occur mainly when the orbit intersects the Earth's shadow.

  13. Lageos orbit decay due to infrared radiation from earth

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    1987-01-01

    Infrared radiation from the earth may be the principal reason for the decay of Lageos' orbit. The radiation heats up the laser retroreflectors embedded in Lageos' aluminum surface. This creates a north-south temperature gradient on the satellite. The gradient in turn causes a force to be exerted on Lageos because of recoil from photons leaving its surface. The delayed heating of the retroreflectors due to their thermal inertia gives the force a net along-track component which always acts like drag. A simple thermal model for the retroreflectors indicates that this thermal drag accounts for about half the observed average along-track acceleration of -3.3 x 10 to the -10th power m/sec squared. The contribution from the aluminum surface to this effect is negligible. The infrared effect cannot explain the large observed fluctuations in drag which occur mainly when the orbit intersects the earth's shadow.

  14. The Geomagnetic Field and Radiation in Near-Earth Orbits

    NASA Technical Reports Server (NTRS)

    Heirtzler, J. R.

    1999-01-01

    This report shows, in detail, how the geomagnetic field interacts with the particle flux of the radiation belts to create a hazard to spacecraft and humans in near-Earth orbit. It illustrates the geometry of the geomagnetic field lines, especially around the area where the field strength is anomalously low in the South Atlantic Ocean. It discusses how the field will probably change in the future and the consequences that may have on hazards in near space.

  15. Single stage earth orbital reusable vehicle. Volume 6: Resources

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The results of a conceptual study of the resource requirements for a single-stage earth-orbital vehicle are presented. All aspects of program costs for the design, manufacture, test, transportation, launch, and facility modifications were considered. The following program costs are discussed: configuration definition, cost groundrules and assumptions, program requirements, work breakdown structure, cost estimation methods, and cost analysis. High cost areas are identified.

  16. Thin-Film Solar Array Earth Orbit Mission Applicability Assessment

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Kerslake, Thomas W.; Hepp, Aloysius F.; Raffaelle, Ryne P.

    2002-01-01

    This is a preliminary assessment of the applicability and spacecraft-level impact of using very lightweight thin-film solar arrays with relatively large deployed areas for representative Earth orbiting missions. The most and least attractive features of thin-film solar arrays are briefly discussed. A simple calculation is then presented illustrating that from a solar array alone mass perspective, larger arrays with less efficient but lighter thin-film solar cells can weigh less than smaller arrays with more efficient but heavier crystalline cells. However, a proper spacecraft-level systems assessment must take into account the additional mass associated with solar array deployed area: the propellant needed to desaturate the momentum accumulated from area-related disturbance torques and to perform aerodynamic drag makeup reboost. The results for such an assessment are presented for a representative low Earth orbit (LEO) mission, as a function of altitude and mission life, and a geostationary Earth orbit (GEO) mission. Discussion of the results includes a list of specific mission types most likely to benefit from using thin-film arrays. NASA Glenn's low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is also briefly discussed to provide a perspective on one approach to achieving this enabling technology. The paper concludes with a list of issues to be addressed prior to use of thin-film solar arrays in space and the observation that with their unique characteristics, very lightweight arrays using efficient, thin-film cells on flexible substrates may become the best array option for a subset of Earth orbiting missions.

  17. NASA's Earth Observations of the Global Environment

    NASA Technical Reports Server (NTRS)

    King, Michael D.

    2005-01-01

    A birds eye view of the Earth from afar and up close reveals the power and magnificence of the Earth and juxtaposes the simultaneous impacts and powerlessness of humankind. The NASA Electronic Theater presents Earth science observations and visualizations in an historical perspective. Fly in from outer space to Africa and Cape Town. See the latest spectacular images from NASA & NOAA remote sensing missions like Meteosat, TRMM, Landsat 7, and Terra, which will be visualized and explained in the context of global change. See visualizations of global data sets currently available from Earth orbiting satellites, including the Earth at night with its city lights, aerosols from biomass burning in the Middle East and Africa, and retreat of the glaciers on Mt. Kilimanjaro. See the dynamics of vegetation growth and decay over Africa over 17 years. New visualization tools allow us to roam & zoom through massive global mosaic images including Landsat and Terra tours of Africa and South America, showing land use and land cover change from Bolivian highlands. Spectacular new visualizations of the global atmosphere & oceans are shown. See massive dust storms sweeping across Africa and across the Atlantic to the Caribbean and Amazon basin. See ocean vortexes and currents that bring up the nutrients to feed tiny phytoplankton and draw the fish, pant whales and fisher- man. See how the ocean blooms in response to these currents and El Nino/La Nifia. We will illustrate these and other topics with a dynamic theater-style presentation, along with animations of satellite launch deployments and orbital mapping to highlight aspects of Earth observations from space.

  18. Optimal aeroassisted return from high earth orbit with plane change

    NASA Astrophysics Data System (ADS)

    Vinh, Nguyen X.; Hanson, John M.

    This paper gives a complete analysis of the problem of aeroassisted return from a high Earth orbit to a low Earth orbit with plane change. A discussion of pure propulsive maneuver leads to the necessary change for improvement of the fuel consumption by inserting in the middle of the trajectory an atmospheric phase to obtain all or part of the required plane change. The variational problem is reduced to a parametric optimization problem by using the known results in optimal impulsive transfer and solving the atmospheric turning problem for storage and use in the optimization process. The coupling effect between space maneuver and atmospheric maneuver is discussed. Depending on the values of the plane change i, the ratios of the radii, n = r 1/r 2 between the orbits and a = r 2/R between the low orbit and the atmosphere, and the maximum lift-to-drag ratio E∗ of the vehicle, the optimal maneuver can be pure propulsive or aeroassisted. For aeroassisted maneuver, the optimal mode can be parabolic, which requires only drag capability of the vehicle, or elliptic. In the elliptic mode, it can be by one-impulse for deorbit and one or two-impulse in postatmospheric flight, or by two-impulse for deorbit with only one impulse for final circularization. It is shown that whenever an impulse is applied, a plane change is made. The necessary conditions for the optimal split of the plane changes are derived and mechanized in a program routine for obtaining the solution.

  19. Auxiliary propulsion technology for advanced Earth-to-orbit vehicles

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.

    1987-01-01

    The payload which can be delivered to orbit by advanced Earth-to-Orbit vehicles is significantly increased by advanced subsystem technology. Any weight which can be saved by advanced subsystem design can be converted to payload at Main Engine Cut Off (MECO) given the same launch vehicle performance. The auxiliary propulsion subsystem and the impetus for the current hydrogen/oxygen technology program is examined. A review of the auxiliary propulsion requirements of advanced Earth-to-Orbit (ETO) vehicles and their proposed missions is given first. Then the performance benefits of hydrogen/oxygen auxiliary propulsion are illustrated using current shuttle data. The proposed auxiliary propulsion subsystem implementation includes liquid hydrogen/liquid oxygen (LH2/LO2) primary Reaction Control System (RCS) engines and gaseous hydrogen/gaseous oxygen (GH2/GO2) vernier RCS engines. A distribution system for the liquid cryogens to the engines is outlined. The possibility of providing one dual-phase engine that can operate on either liquid or gaseous propellants is being explored, as well as the simultaneous firing of redundant primary RCS thrusters to provide Orbital Maneuvering System (OMS) level impulse. Scavenging of propellants from integral main engine tankage is proposed to utilize main engine tank residuals and to combine launch vehicle and subsystem reserves.

  20. Orbital and Physical Characteristics of Meter-sized Earth Impactors

    NASA Astrophysics Data System (ADS)

    Brown, Peter G.; Wiegert, Paul; Clark, David; Tagliaferri, Edward

    2015-11-01

    We have analysed the orbits and ablation characteristics in the atmosphere of more than 60 earth-impacting meteoroids of one meter in diameter or larger. Using heights at peak luminosity as a proxy for strength, we find that there is roughly an order of magnitude spread in the apparent strength of the population of meter-sized impactors at the Earth. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. We find ~10-15% of our objects have a probable cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, show evidence for the expected weaker than average structure compared to asteroidal bodies. Almost all impactors show peak brightness between 20-40 km altitude. Several events have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though all were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several NEOs in our population with the Taurid meteoroid complex. No other major meteoroid streams show linkages with the pre-atmospheric orbits of our meter-class impactors. Our events cover almost four orders of magnitude in mass, but no trend in height of peak brightness is evident, suggesting no strong trend in strength with size for small NEOs, a finding consistent with the results of Popova et al (2011).

  1. Space life sciences: radiation risk assessment and radiation measurements in low Earth orbit.

    PubMed

    2004-01-01

    The volume contains papers presented at COSPAR symposia in October 2002 about radiation risk assessment and radiation measurements in low Earth orbit. The risk assessment symposium brought together multidisciplinary expertise including physicists, biologists, and theoretical modelers. Topics included current knowledge about known and predicted radiation environments, radiation shielding, physics cross section models, improved ion beam transport codes, biological demonstrations of specific shielding materials and applications to a manned mission to Mars, advancements in biological measurement of radiation-induced protein expression profiles, and integration of physical and biological parameters to assess key elements of radiation risk. Papers from the radiation measurements in low Earth orbit symposium included data about dose, linear energy transfer spectra, and charge spectra from recent measurements on the International Space Station (ISS), comparison between calculations and measurements of dose distribution inside a human phantom and the neutron component inside the ISS; and reviews of trapped antiprotons and positrons inside the Earth's magnetosphere. PMID:15880912

  2. Interaction between subdaily Earth rotation parameters and GPS orbits

    NASA Astrophysics Data System (ADS)

    Panafidina, Natalia; Seitz, Manuela; Hugentobler, Urs

    2013-04-01

    In processing GPS observations the geodetic parameters like station coordinates and ERPs (Earth rotation parameters) are estimated w.r.t. the celestial reference system realized by the satellite orbits. The interactions/correlations between estimated GPS orbis and other parameters may lead to numerical problems with the solution and introduce systematic errors in the computed values: the well known correlations comprise 1) the correlation between the orbital parameters determining the orientation of the orbital plane in inertial space and the nutation and 2) in the case of estimating ERPs with subdaily resolution the correlation between retrograde diurnal polar motion and nutation (and so the respective orbital elements). In this contribution we study the interaction between the GPS orbits and subdaily model for the ERPs. Existing subdaily ERP model recommended by the IERS comprises ~100 terms in polar motion and ~70 terms in Universal Time at diurnal and semidiurnal tidal periods. We use a long time series of daily normal equation systems (NEQ) obtaine from GPS observations from 1994 till 2007 where the ERPs with 1-hour resolution are transformed into tidal terms and the influence of the tidal terms with different frequencies on the estimated orbital parameters is considered. We found that although there is no algebraic correlation in the NEQ between the individual orbital parameters and the tidal terms, the changes in the amplitudes of tidal terms with periods close to 24 hours can be better accmodated by systematic changes in the orbital parameters than for tidal terms with other periods. Since the variation in Earth rotation with the period of siderial day (23.93h, tide K1) in terrestrial frame has in inertial space the same period as the period of revolution of GPS satellites, the K1 tidal term in polar motion is seen by the satellites as a permanent shift. The tidal terms with close periods (from ~24.13h to ~23.80h) are seen as a slow rotation of the

  3. Internal Charging Design Environments for the Earths Radiation Belts

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Edwards, David L.

    2009-01-01

    Relativistic electrons in the Earth's radiation belts are a widely recognized threat to spacecraft because they penetrate lightly shielded vehicle hulls and deep into insulating materials where they accumulate to sufficient levels to produce electrostatic discharges. Strategies for evaluating the magnitude of the relativistic electron flux environment and its potential for producing ESD events are varied. Simple "rule of thumb" estimates such as the widely used 10(exp 10) e-/sq cm fluence within 10 hour threshold for the onset of pulsing in dielectric materials provide a quick estimate of when to expect charging issues. More sophisticated strategies based on models of the trapped electron flux within the Earth s magnetic field provide time dependent estimates of electron flux along spacecraft orbits and orbit integrate electron flux. Finally, measurements of electron flux can be used to demonstrate mean and extreme relativistic electron environments. This presentation will evaluate strategies used to specify energetic electron flux and fluence environments along spacecraft trajectories in the Earth s radiation belts.

  4. The solar-flare induced earth's environment

    NASA Technical Reports Server (NTRS)

    Wu, S. T.; Dryer, M.; Han, S. M.

    1985-01-01

    A composite numerical simulation model developed from a series of MHD models was used to compute the solar-flare-generated disturbances of physical parameters, such as density, temperature, velocity, and magnetic field from the solar surface (i.e., the photospheric level) to the earth's environment. It is shown that the disturbed earth's environment at high latitudes can be approximated by starting with the knowledge of the occurrence and the strength of a solar flare, then simulating the evolutionary consequences of the solar disturbance through interplanetary space up to and through the magnetosphere.

  5. Development and testing of coatings for orbital space radiation environments.

    PubMed

    Pellicori, Samuel F; Martinez, Carol L; Hausgen, Paul; Wilt, David

    2014-02-01

    Specific coating processes and materials were investigated in the quest to develop multilayer coatings with greater tolerance to space radiation exposure. Ultraviolet reflection (UVR) and wide-band antireflection (AR) multilayer coatings were deposited on solar cell covers and test substrates and subsequently exposed to simulated space environments and also flown on the Materials International Space Station Experiment-7 (MISSE-7) to determine their space environment stability. Functional solar cells integrated with these coatings underwent simulated UV and MISSE-7 low earth orbit flight exposure. The effects of UV, proton, and atomic oxygen exposure on coatings and on assembled solar cells as related to the implemented deposition processes and material compositions were small. The UVR/AR coatings protected flexible polymer substrate materials that are intended for future flexible multijunction cell arrays to be deployed from rolls. Progress was made toward developing stable and protective coatings for extended space-mission applications. Test results are presented. PMID:24514237

  6. A mixed fleet transportation system to low Earth orbit

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Based on a provided mission model, this project considered three different classes of launch vehicles for possible use: (1) modifications to the current Space Transportation System, or replacement by a second-generation vehicle using current technology; (2) a heavy-lift cargo vehicle, designed to minimize the cost of bulk cargo to low earth orbit; and (3) an advanced man-rated system incorporating technology anticipated for the year 1995. The mission model provided included commercial, scientific, and military payloads for the years 1990 through 2010. Use of the current Space Transportation System was also permitted in the final fleet sizing analysis. The near-term shuttle group performed trade studies on a number of modifications and variations before selecting a new vehicle design, incorporating a fly-back reusable first stage and reduced-size orbiter. Orbiter payload was limited to 5000 kg (priority items), with up to 25,000 kg of payload carried in a forward payload bay within the nose shroud of the orbiter external tank. This allowed reduction of orbiter size, without significant loss of reusability.

  7. Secular tidal changes in lunar orbit and Earth rotation

    NASA Astrophysics Data System (ADS)

    Williams, James G.; Boggs, Dale H.

    2016-06-01

    Small tidal forces in the Earth-Moon system cause detectable changes in the orbit. Tidal energy dissipation causes secular rates in the lunar mean motion n, semimajor axis a, and eccentricity e. Terrestrial dissipation causes most of the tidal change in n and a, but lunar dissipation decreases eccentricity rate. Terrestrial tidal dissipation also slows the rotation of the Earth and increases obliquity. A tidal acceleration model is used for integration of the lunar orbit. Analysis of lunar laser ranging (LLR) data provides two or three terrestrial and two lunar dissipation parameters. Additional parameters come from geophysical knowledge of terrestrial tides. When those parameters are converted to secular rates for orbit elements, one obtains dn/dt = -25.97± 0.05 ''/ cent2 , da/dt = 38.30 ± 0.08 mm/year, and di/dt = -0.5 ± 0.1 μ as/year. Solving for two terrestrial time delays and an extra de/dt from unspecified causes gives ˜ 3× 10^{-12} /year for the latter; solving for three LLR tidal time delays without the extra de/dt gives a larger phase lag of the N2 tide so that total de/dt = (1.50 ± 0.10)× 10^{-11} /year. For total dn/dt, there is ≤ 1 % difference between geophysical models of average tidal dissipation in oceans and solid Earth and LLR results, and most of that difference comes from diurnal tides. The geophysical model predicts that tidal deceleration of Earth rotation is -1316 '' /cent2 or 87.5 s/cent2 for UT1-AT, a 2.395 ms/cent increase in the length of day, and an obliquity rate of 9 μ as/year. For evolution during past times of slow recession, the eccentricity rate can be negative.

  8. Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit

    NASA Technical Reports Server (NTRS)

    Parker, Joel J. K.; Valdez, Jennifer E.; Bauer, Frank H.; Moreau, Michael C.

    2016-01-01

    GPS (Global Positioning System) Space Service Volume (SSV) signal environment is from 3,000-36,000 kilometers altitude. Current SSV specifications only capture performance provided by signals transmitted within 23.5(L1) or 26(L2-L5) off-nadir angle. Recent on-orbit data lessons learned show significant PNT (Positioning, Navigation and Timing) performance improvements when the full aggregate signal is used. Numerous military civil operational missions in High Geosynchronous Earth Orbit (HEOGEO) utilize the full signal to enhance vehicle PNT performance

  9. Use of the VLBI delay observable for orbit determination of Earth-orbiting VLBI satellites

    NASA Technical Reports Server (NTRS)

    Ulvestad, J. S.

    1992-01-01

    Very long-baseline interferometry (VLBI) observations using a radio telescope in Earth orbit were performed first in the 1980s. Two spacecraft dedicated to VLBI are scheduled for launch in 1995; the primary scientific goals of these missions will be astrophysical in nature. This article addresses the use of space VLBI delay data for the additional purpose of improving the orbit determination of the Earth-orbiting spacecraft. In an idealized case of quasi-simultaneous observations of three radio sources in orthogonal directions, analytical expressions are found for the instantaneous spacecraft position and its error. The typical position error is at least as large as the distance corresponding to the delay measurement accuracy but can be much greater for some geometries. A number of practical considerations, such as system noise and imperfect calibrations, set bounds on the orbit-determination accuracy realistically achievable using space VLBI delay data. These effects limit the spacecraft position accuracy to at least 35 cm (and probably 3 m or more) for the first generation of dedicated space VLBI experiments. Even a 35-cm orbital accuracy would fail to provide global VLBI astrometry as accurate as ground-only VLBI. Recommended charges in future space VLBI missions are unlikely to make space VLBI competitive with ground-only VLBI in global astrometric measurements.

  10. Spacecraft transfer trajectory design exploiting resonant orbits in multi-body environments

    NASA Astrophysics Data System (ADS)

    Vaquero Escribano, Tatiana Mar

    Historically, resonant orbits have been employed in mission design for multiple planetary flyby trajectories and, more recently, as a source of long-term orbital stability. For instance, in support of a mission concept in NASA's Outer Planets Program, the Jupiter Europa Orbiter spacecraft is designed to encounter two different resonances with Europa during the 'endgame' phase, leading to Europa orbit insertion on the final pass. In 2011, the Interstellar Boundary Explorer spacecraft was inserted into a stable out-of-plane lunar-resonant orbit, the first of this type for a spacecraft in a long-term Earth orbit. However, resonant orbits have not yet been significantly explored as transfer mechanisms between non-resonant orbits in multi-body systems. This research effort focuses on incorporating resonant orbits into the design process to potentially enable the construction of more efficient or even novel transfer scenarios. Thus, the goals in this investigation are twofold: i) to expand the orbit architecture in multi-body environments by cataloging families of resonant orbits, and ii) to assess the role of such families in the design of transfer trajectories with specific patterns and itineraries. The benefits and advantages of employing resonant orbits in the design process are demonstrated through a variety of astrodynamics applications in several multi-body systems. In the Earth-Moon system, locally optimal transfer trajectories from low Earth orbit to selected libration point orbits are designed by leveraging conic arcs and invariant manifolds associated with resonant orbits. Resonant manifolds in the Earth-Moon system offer trajectories that tour the entire space within reasonable time intervals, facilitating the design of libration point orbit tours as well as Earth-Moon cyclers. In the Saturnian system, natural transitions between resonant and libration point orbits are sought and the problem of accessing Hyperion from orbits that are resonant with Titan is

  11. Earth observation mission operation of COMS during in-orbit test

    NASA Astrophysics Data System (ADS)

    Cho, Young-Min

    2011-11-01

    Communication Ocean Meteorological Satellite (COMS) for the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service was launched onto Geostationary Earth Orbit on June 27, 2010 and it is currently under normal operation service after the In-Orbit Test (IOT) phase. The COMS is located on 128.2° East of the geostationary orbit. In order to perform the three missions, the COMS has 3 separate payloads, the meteorological imager (MI), the Geostationary Ocean Color Imager (GOCI), and the Ka-band antenna. Each payload is dedicated to one of the three missions, respectively. The MI and GOCI perform the Earth observation mission of meteorological observation and ocean monitoring, respectively. During the IOT phase the functionality and the performance of many aspects of the COMS satellite and ground station have been checked through the Earth observation mission operation for the observation of the meteorological phenomenon over several areas of the Earth and the monitoring of marine environments around the Korean peninsula. The Earth observation mission operation of COMS during the IOT phase is introduced in terms of mission operation characteristics, mission planning, and mission operation results for the missions of meteorological observation and ocean monitoring, respectively.

  12. Oxidation-resistant reflective surfaces for solar dynamic power generation in near earth orbit

    NASA Technical Reports Server (NTRS)

    Gulino, Daniel A.; Egger, Robert A.; Banholzer, William F.

    1987-01-01

    Reflective surfaces for Space Station power generation systems are required to withstand the atomic oxygen-dominated environment of near earth orbit. Thin films of platinum and rhodium, which are corrosion resistant reflective metals, have been deposited by ion beam sputter deposition onto various substrate materials. Solar reflectances were then measured as a function of time of exposure to a RF-generated air plasma.

  13. Statistical Analysis of Interference Between Earth Stations and Earth-Orbiting Satellites

    NASA Technical Reports Server (NTRS)

    Bishop, D.

    1994-01-01

    Determination of the potential for radio frequency interference between Earth stations and orbiting spacecraft is often desirable. This information can be used to select frequencies for radio systems to avoid interference or it can be used to determine if coordination between radio systems is necessary. Also, it is useful for planning emission standards and filtering requirements for future telecommunications equipment. A model is developed that will determine the statistics of interference between Earth stations and elliptical orbiting spacecraft. The model uses orbital dynamics, detailed antenna patterns, and spectral characteristics to obtain accurate levels of interference at the victim receiver. The model is programmed into a computer simulation to obtain long term statistics of interference.

  14. Hemispheric Bias in Earth's response to orbital forcing

    NASA Astrophysics Data System (ADS)

    Roychowdhury, Rajarshi; DeConto, Rob

    2014-05-01

    Today, there is an unequal distribution of land and water between the two hemispheres. The Northern Hemisphere has about 68% of the total landmass on earth, while the Southern hemisphere has less than half of the northern hemisphere land (~32%). It is observed that the Southern Hemisphere climates tend to be slightly milder than those in the Northern Hemisphere at similar latitudes, except in the Antarctic which is colder than the Arctic. This variance in climate can be attributed to two reasons: the current precessional configuration of the earth; and the fact that the Southern Hemisphere has significantly more ocean and much less land. The objective of this paper is to determine a hemispheric bias in climate due to unequal land distribution in the Northern and Southern Hemispheres. In this study, we use physically based climate models to gain insights into the role of Northern Hemisphere landmass distribution affecting the Southern Hemisphere climate and vice versa. We use hypothetical symmetric earth models in which landmass distribution is mirrored along the equator. We use these hypothetical landmass distributions to run a control simulation to provide the boundary conditions for a number of branched runs with a range of modified orbital parameters. The aim is to isolate the effects of the modified landmass distribution from the usual effects of orbital forcing. Using a Northern-Hemisphere symmetric earth model and a Southern-Hemisphere symmetric earth model, we are able to draw conclusions regarding the Northern influence on Southern Hemisphere and vice versa. With this information, a hemispheric bias map is constructed which has the potential to reveal useful insights into many unsolved climate problems. Precession and Obliquity effects are also studied in isolation on the calculated hemispheric bias. An improved understanding of the hemispheric bias caused by continental distribution will help associate past climates to paleocontinental reconstructions with

  15. PôDET: A Centre for Earth Dynamical Environment

    NASA Astrophysics Data System (ADS)

    Hestroffer, D.; Deleflie, F.

    2013-11-01

    The monitoring of the Earth space environment has gained some importance these last decades, in particular at the European level, partly because the phenomenon which origin come from space can have socio-economic consequences; and also because our understanding of those phenomenon - their associated prediction and risks - is still limited. For instance, the Space Situational Awareness programme (SSA) at ESA has set up in 2013 a centre and network for aspects connected to space debris (SST), to space weather (SW), and to near-Earth objects (NEO). At IMCCE, the Pôle sur la dynamique de l'environnement terrestre} (PODET, \\url{podet.imcce.fr}) for the Earth dynamical environment is studying effects and prediction for natural and artificial objects gravitating in the Earth vicinity. These studies englobe near-Earth objects, asteroids, comets, meteoroids, meteorite streams, and space debris. For all object types that are concerned, a general scheme of a functional analysis has been developed. It encompasses data acquisition with dedicated observations--essentially astrometric--or database queries, orbit determination or adjustment, prediction and ephemerides, and eventually impact probability computation and data dissemination. We develop here the general context of this action, the PôDET project, its scientific objectives, interaction with other disciplines, and the development in progress for dedicated tools.

  16. Simulation of the low earth orbital atomic oxygen interaction with materials by means of an oxygen ion beam

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Paulsen, Phillip E.; Steuber, Thomas J.

    1989-01-01

    Atomic oxygen is the predominant species in low-Earth orbit between the altitudes of 180 and 650 km. These highly reactive atoms are a result of photodissociation of diatomic oxygen molecules from solar photons having a wavelength less than or equal to 2430A. Spacecraft in low-Earth orbit collide with atomic oxygen in the 3P ground state at impact energies of approximately 4.2 to 4.5 eV. As a consequence, organic materials previously used for high altitude geosynchronous spacecraft are severely oxidized in the low-Earth orbital environment. The evaluation of materials durability to atomic oxygen requires ground simulation of this environment to cost effectively screen materials for durability. Directed broad beam oxygen sources are necessary to evaluate potential spacecraft materials performance before and after exposure to the simulated low-Earth orbital environment. This paper presents a description of a low energy, broad oxygen ion beam source used to simulate the low-Earth orbital atomic oxygen environment. The results of materials interaction with this beam and comparison with actual in-space tests of the same meterials will be discussed. Resulting surface morphologies appear to closely replicate those observed in space tests.

  17. Advantages of High vs. Low Earth Orbit for SIRTF

    NASA Technical Reports Server (NTRS)

    Eisenhardt, Peter; Werner, Michael W.

    1989-01-01

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

  18. Analyses of space environment effects on active fiber optic links orbited aboard the LDEF

    NASA Technical Reports Server (NTRS)

    Taylor, Edward W.; Monarski, T. W.; Berry, J. N.; Sanchez, A. D.; Padden, R. J.; Chapman, S. P.

    1993-01-01

    The results of the 'Preliminary Analysis of WL Experiment no. 701, Space Environment Effects on Operating Fiber Optic Systems,' is correlated with space simulated post retrieval terrestrial studies performed on the M0004 experiment. Temperature cycling measurements were performed on the active optical data links for the purpose of assessing link signal to noise ratio and bit error rate performance some 69 months following the experiment deployment in low Earth orbit. The early results indicate a high correlation between pre-orbit, orbit, and post-orbit functionality of the first known and longest space demonstration of operating fiber optic systems.

  19. Near Earth Asteroids- Prospection, Orbit Modification and Mining

    NASA Astrophysics Data System (ADS)

    Grandl, W.; Bazso, A.

    2014-04-01

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

  20. The Near-Earth Plasma Environment

    NASA Technical Reports Server (NTRS)

    Pfaff, Robert F., Jr.

    2012-01-01

    An overview of the plasma environment near the earth is provided. We describe how the near-earth plasma is formed, including photo-ionization from solar photons and impact ionization at high latitudes from energetic particles. We review the fundamental characteristics of the earth's plasma environment, with emphasis on the ionosphere and its interactions with the extended neutral atmosphere. Important processes that control ionospheric physics at low, middle, and high latitudes are discussed. The general dynamics and morphology of the ionized gas at mid- and low-latitudes are described including electrodynamic contributions from wind-driven dynamos, tides, and planetary-scale waves. The unique properties of the near-earth plasma and its associated currents at high latitudes are shown to depend on precipitating auroral charged particles and strong electric fields which map earthward from the magnetosphere. The upper atmosphere is shown to have profound effects on the transfer of energy and momentum between the high-latitude plasma and the neutral constituents. The article concludes with a discussion of how the near-earth plasma responds to magnetic storms associated with solar disturbances.

  1. Nickel hydrogen low Earth orbit test program update and status

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  2. Aerodynamics of Satellites on a Super Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Fujita, Kazuhisa; Noda, Atsushi

    2008-12-01

    The Super Low Altitude Test Satellite is an engineering test satellite currently under development in Japan Aerospace Exploration Agency in an attempt to open a new frontier of space utilization on extremely low earth orbits. In the presence of aerodynamic forces acting on the satellite, the altitude and attitude of the satellite are maintained by ion engines so that the aerodynamic drag can be canceled. Thus, it is of primary importance to accurately assess the aerodynamics characteristics of the satellite prior to flight. In this article, the aerodynamic coefficients of the satellite are calculated for orbital altitudes from 160 to 300 km, taking into account the Maxwell accommodation of particles on the satellite surface and the free stream chemical composition. The activated atomic oxygen fluence rate on the surface, which is expected to cause considerable damages on the surface material, is estimated as well.

  3. Technology requirements for advanced earth-orbital transportation systems

    NASA Technical Reports Server (NTRS)

    Haefeli, R. C.; Littler, E. G.; Hurley, J. B.; Winter, M. G.

    1977-01-01

    Areas of advanced technology that are either critical or offer significant benefits to the development of future Earth-orbit transportation systems were identified. Technology assessment was based on the application of these technologies to fully reusable, single-stage-to-orbit (SSTO) vehicle concepts with horizontal landing capability. Study guidelines included mission requirements similar to space shuttle, an operational capability begining in 1995, and main propulsion to be advanced hydrogen-fueled rocket engines. Also evaluated was the technical and economic feasibility of this class of SSTO concepts and the comparative features of three operational take-off modes, which were vertical boost, horizontal sled launch, and horizontal take-off with subsequent inflight fueling. Projections of both normal and accelerated technology growth were made. Figures of merit were derived to provide relative rankings of technology areas. The influence of selected accelerated areas on vehicle design and program costs was analyzed by developing near-optimum point designs.

  4. Low Earth Orbit satellite/terrestrial mobile service compatibility

    NASA Technical Reports Server (NTRS)

    Sheriff, Ray E.; Gardiner, John G.

    1993-01-01

    Currently the geostationary type of satellite is the only one used to provide commercial mobile-satellite communication services. Low earth orbit (LEO) satellite systems are now being proposed as a future alternative. By the implementation of LEO satellite systems, predicted at between 5 and 8 years time, mobile space/terrestrial technology will have progressed to the third generation stage of development. This paper considers the system issues that will need to be addressed when developing a dual mode terminal, enabling access to both terrestrial and LEO satellite systems.

  5. Geostationary orbit Earth science platform concepts for global change monitoring

    NASA Technical Reports Server (NTRS)

    Farmer, Jeffery T.; Campbell, Thomas G.; Davis, William T.; Garn, Paul A.; King, Charles B.; Jackson, Cheryl C.

    1991-01-01

    Functionality of a geostationary spacecraft to support Earth science regional process research is identified. Most regional process studies require high spatial and temporal resolution. These high temporal resolutions are on the order of 30 minutes and may be achievable with instruments positioned in a geostationary orbit. A complement of typical existing or near term instruments are identified to take advantage of this altitude. This set of instruments is listed, and the requirements these instruments impose on a spacecraft are discussed. A brief description of the geostationary spacecraft concepts which support these instruments is presented.

  6. Gas-Surface Interactions in Low-Earth Orbit

    NASA Astrophysics Data System (ADS)

    Moe, Kenneth; Moe, Mildred M.

    2011-05-01

    When the space age began, some aerodynamicists expected that the surfaces of spacecraft would be cleaned by desorption in the high vacuum of space; while others, familiar with experiments on engineering surfaces, believed that satellite surfaces would be contaminated. During subsequent decades, satellite evidence has accumulated, showing that surfaces in low-Earth orbit are contaminated by adsorbed atomic oxygen and its reaction products. These contaminants cause accommodation coefficients to be high, and the angular distribution of reemitted molecules to be nearly diffuse. These surface conditions must be considered in calculating satellite drag coefficients in free-molecular flow. We describe the experimental and theoretical developments which have led to these conclusions.

  7. Computer simulation results of attitude estimation of earth orbiting satellites

    NASA Technical Reports Server (NTRS)

    Kou, S. R.

    1976-01-01

    Computer simulation results of attitude estimation of Earth-orbiting satellites (including Space Telescope) subjected to environmental disturbances and noises are presented. Decomposed linear recursive filter and Kalman filter were used as estimation tools. Six programs were developed for this simulation, and all were written in the basic language and were run on HP 9830A and HP 9866A computers. Simulation results show that a decomposed linear recursive filter is accurate in estimation and fast in response time. Furthermore, for higher order systems, this filter has computational advantages (i.e., less integration errors and roundoff errors) over a Kalman filter.

  8. Energy storage for low earth orbit operations at high power

    NASA Technical Reports Server (NTRS)

    Trout, J. B.

    1979-01-01

    Results are presented of an in-house study of relative sizes and technology needs of three energy storage systems for high power, low earth orbit power systems. The systems compared are nickel-cadmium batteries, nickel-hydrogen batteries, and regenerative fuel cell systems (RFCS). RFCS based on hydrogen-oxygen and hydrogen-chlorine reactants are examined. Those components of the total power system which are significantly impacted by energy storage system selection; e.g., solar array, reactant storage tanks and radiator sizes, are included incrementally in the weights of the systems compared.

  9. Evaluation of Bulk Charging in Geostationary Transfer Orbit and Earth Escape Trajectories Using the Numit 1-D Charging Model

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Coffey, Victoria N.; Parker, Linda N.; Blackwell, William C., Jr.; Jun, Insoo; Garrett, Henry B.

    2007-01-01

    The NUMIT 1-dimensional bulk charging model is used as a screening to ol for evaluating time-dependent bulk internal or deep dielectric) ch arging of dielectrics exposed to penetrating electron environments. T he code is modified to accept time dependent electron flux time serie s along satellite orbits for the electron environment inputs instead of using the static electron flux environment input originally used b y the code and widely adopted in bulk charging models. Application of the screening technique ts demonstrated for three cases of spacecraf t exposure within the Earth's radiation belts including a geostationa ry transfer orbit and an Earth-Moon transit trajectory for a range of orbit inclinations. Electric fields and charge densities are compute d for dielectric materials with varying electrical properties exposed to relativistic electron environments along the orbits. Our objectiv e is to demonstrate a preliminary application of the time-dependent e nvironments input to the NUMIT code for evaluating charging risks to exposed dielectrics used on spacecraft when exposed to the Earth's ra diation belts. The results demonstrate that the NUMIT electric field values in GTO orbits with multiple encounters with the Earth's radiat ion belts are consistent with previous studies of charging in GTO orb its and that potential threat conditions for electrostatic discharge exist on lunar transit trajectories depending on the electrical proper ties of the materials exposed to the radiation environment.

  10. Analysis of orbital configurations for geocenter determination with GPS and low-Earth orbiters

    NASA Astrophysics Data System (ADS)

    Kuang, Da; Bar-Sever, Yoaz; Haines, Bruce

    2015-05-01

    We use a series of simulated scenarios to characterize the observability of geocenter location with GPS tracking data. We examine in particular the improvement realized when a GPS receiver in low Earth orbit (LEO) augments the ground network. Various orbital configurations for the LEO are considered and the observability of geocenter location based on GPS tracking is compared to that based on satellite laser ranging (SLR). The distance between a satellite and a ground tracking-site is the primary measurement, and Earth rotation plays important role in determining the geocenter location. Compared to SLR, which directly and unambiguously measures this distance, terrestrial GPS observations provide a weaker (relative) measurement for geocenter location determination. The estimation of GPS transmitter and receiver clock errors, which is equivalent to double differencing four simultaneous range measurements, removes much of this absolute distance information. We show that when ground GPS tracking data are augmented with precise measurements from a GPS receiver onboard a LEO satellite, the sensitivity of the data to geocenter location increases by more than a factor of two for Z-component. The geometric diversity underlying the varying baselines between the LEO and ground stations promotes improved global observability, and renders the GPS technique comparable to SLR in terms of information content for geocenter location determination. We assess a variety of LEO orbital configurations, including the proposed orbit for the geodetic reference antenna in space mission concept. The results suggest that a retrograde LEO with altitude near 3,000 km is favorable for geocenter determination.

  11. Solar Effects of Low-Earth Orbit objects in ORDEM 3.0

    NASA Technical Reports Server (NTRS)

    Vavrin, A. B.; Anz-Meador, P.; Kelley, R. L.

    2014-01-01

    Variances in atmospheric density are directly related to the variances in solar flux intensity between 11- year solar cycles. The Orbital Debris Engineering Model (ORDEM 3.0) uses a solar flux table as input for calculating orbital lifetime of intact and debris objects in Low-Earth Orbit. Long term projections in solar flux activity developed by the NASA Orbital Debris Program Office (ODPO) extend the National Oceanic and Atmospheric Administration Space Environment Center (NOAA/SEC) daily historical flux values with a 5-year projection. For purposes of programmatic scheduling, the Q2 2009 solar flux table was chosen for ORDEM 3.0. Current solar flux activity shows that the current solar cycle has entered a period of lower solar flux intensity than previously forecasted in 2009. This results in a deviation of the true orbital debris environment propagation in ORDEM 3.0. In this paper, we present updated orbital debris populations in LEO using the latest solar flux values. We discuss the effects on recent breakup events such as the FY-1C anti-satellite test and the Iridium 33 / Cosmos 2251 accidental collision. Justifications for chosen solar flux tables are discussed.

  12. Innovations in mission architectures for exploration beyond low Earth orbit.

    PubMed

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

    2003-01-01

    Through the application of advanced technologies and mission concepts, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to science driven; technology enabled human and robotic exploration. Numbers and masses of vehicles required are greatly reduced, yet the pursuit of a broader range of science objectives is enabled. The scope of human missions considered range from the assembly and maintenance of large aperture telescopes for emplacement at the Sun-Earth libration point L2, to human missions to asteroids, the moon and Mars. The vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities, which allows for future decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration. PMID:14649260

  13. Autonomous optical navigation for orbits around Earth-Moon collinear libration points

    NASA Astrophysics Data System (ADS)

    Virgili Llop, Josep

    2013-05-01

    The analysis of optical navigation in an Earth-Moon libration point orbit is examined. Missions to libration points have been winning momentum during the last decades. Its unique characteristics make it suitable for a number of operational and scientific goals. Literature aimed to study dynamics, guidance and control of unstable orbits around collinear libration points is vast. In particular, several papers deal with the optimisation of the Δv budget associated to the station-keeping of these orbits. One of the results obtained in literature establishes the critical character of the Moon-Earth system in this aspect. The reason for this behaviour is twofold: high Δv cost and short optimal manoeuvre spacing. Optical autonomous navigation can address the issue of allowing a more flexible manoeuvre design. This technology has been selected to overcome similar difficulties in other critical scenarios. This paper analyses in detail this solution. A whole GNC system is defined to meet the requirements imposed by the unstable dynamic environment. Finally, a real simulation of a spacecraft following a halo orbit of the L2 Moon-Earth system is carried out to assess the actual capabilities of the optical navigation in this scenario.

  14. Two Earth-sized planets orbiting Kepler-20.

    PubMed

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

    2012-02-01

    Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R(⊕)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R(⊕)) and the other smaller than the Earth (0.87R(⊕)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere. PMID:22186831

  15. Magnetically levitated space elevator to low-earth orbit.

    SciTech Connect

    Hull, J. R.; Mulcahy, T. M.

    2001-07-02

    The properties of currently available NbTi superconductor and carbon-fiber structural materials enable the possibility of constructing a magnetically levitated space elevator from the earth's surface up to an altitude of {approx} 200 km. The magnetic part of the elevator consists of a long loop of current-carrying NbTi, composed of one length that is attached to the earth's surface in an east-west direction and a levitated-arch portion. The critical current density of NbTi is sufficiently high that these conductors will stably levitate in the earth's magnetic field. The magnetic self-field from the loop increases the levitational force and for some geometries assists levitational stability. The 200-km maximum height of the levitated arch is limited by the allowable stresses of the structural material. The loop is cryogenically cooled with helium, and the system utilizes intermediate pumping and cooling stations along both the ground and the levitated portion of the loop, similar to other large terrestrial cryogenic systems. Mechanically suspended from the basic loop is an elevator structure, upon which mass can be moved between the earth's surface and the top of the loop by a linear electric motor or other mechanical or electrical means. At the top of the loop, vehicles may be accelerated to orbital velocity or higher by rocket motors, electromagnetic propulsion, or hybrid methods.

  16. Spectral Fingerprints of Earth-like Planets Orbiting Other Stars

    NASA Astrophysics Data System (ADS)

    Rugheimer, Sarah; Kaltenegger, Lisa; Sasselov, Dimitar

    2015-01-01

    A wide range of potentially rocky planets in the habitable zone (HZ) have been detected by Kepler as well as ground-based searches. The type of host star influences our ability to detect atmospheric features with future space- and ground-based telescopes like JWST and E-ELT. We present a complete suit of stellar models as well as model atmospheres for an Earth-analogue planets in their HZ for stellar effective temperature from Teff = 2300K to 7000K, sampling the entire FGKM stellar type range. The UV emission from a planet's host star dominates the photochemistry and thus the resultant observable spectral features of the planet. Using the latest UV spectra obtained by Hubble as well as IUE, we model the effect of activity on Earth-like planets. We focus on the primary detectable atmospheric features that indicate habitability on Earth, namely: H2O, O3, CH4, N2O and CH3Cl. We model the emergent as well as transit spectra of Earth-analogue planets orbiting our grid of FGKM stars in the VIS/NIR (0.4 - 4 microns) and the IR (5 - 20 microns) range as input for future missions like JWST and concepts like Darwin/TPF.

  17. Modelling the near-Earth space environment using LDEF data

    NASA Technical Reports Server (NTRS)

    Atkinson, Dale R.; Coombs, Cassandra R.; Crowell, Lawrence B.; Watts, Alan J.

    1992-01-01

    Near-Earth space is a dynamic environment, that is currently not well understood. In an effort to better characterize the near-Earth space environment, this study compares the results of actual impact crater measurement data and the Space Environment (SPENV) Program developed in-house at POD, to theoretical models established by Kessler (NASA TM-100471, 1987) and Cour-Palais (NASA SP-8013, 1969). With the continuing escalation of debris there will exist a definite hazard to unmanned satellites as well as manned operations. Since the smaller non-trackable debris has the highest impact rate, it is clearly necessary to establish the true debris environment for all particle sizes. Proper comprehension of the near-Earth space environment and its origin will permit improvement in spacecraft design and mission planning, thereby reducing potential disasters and extreme costs. Results of this study directly relate to the survivability of future spacecraft and satellites that are to travel through and/or reside in low Earth orbit (LEO). More specifically, these data are being used to: (1) characterize the effects of the LEO micrometeoroid an debris environment on satellite designs and components; (2) update the current theoretical micrometeoroid and debris models for LEO; (3) help assess the survivability of spacecraft and satellites that must travel through or reside in LEO, and the probability of their collision with already resident debris; and (4) help define and evaluate future debris mitigation and disposal methods. Combined model predictions match relatively well with the LDEF data for impact craters larger than approximately 0.05 cm, diameter; however, for smaller impact craters, the combined predictions diverge and do not reflect the sporadic clouds identified by the Interplanetary Dust Experiment (IDE) aboard LDEF. The divergences cannot currently be explained by the authors or model developers. The mean flux of small craters (approximately 0.05 cm diameter) is

  18. Atmospheric environment during maneuvering descent from Martian orbit

    NASA Technical Reports Server (NTRS)

    Tauber, Michael E.; Bowles, Jeffrey V.; Yang, Lily

    1989-01-01

    This paper presents an analysis of the atmospheric maneuvering capability of a vehicle designated to land on the Martian surface, together with an analysis of the entry environment encountered by the vehicle. A maximum lift/drag ratio of 2.3 was used for all trajectory calculations. The maximum achievable lateral ranges varied from about 3400 km to 2500 km for entry velocities of 5 km/s (from a highly elliptical Martian orbit) and 3.5 km/s (from a low-altitude lower-speed orbit), respectively. It is shown that the peak decelerations are an order of magnitude higher for the 5-km/s entries than for the 3.5-km/s entries. The vehicle entering at 3.5 km/s along a gliding trajectory encountered a much more benign atmospheric environment. In addition, the glider's peak deceleration was found to be only about 0.7 earth g, making the shallow flight path ideal for manned vehicles whose crews might be physically weakened by the long voyage to Mars.

  19. Capturing near-Earth asteroids into bounded Earth orbits using gravity assist

    NASA Astrophysics Data System (ADS)

    Bao, Changchun; Yang, Hongwei; Barsbold, Baza; Baoyin, Hexi

    2015-12-01

    In this paper, capturing Near-Earth asteroids (NEAs) into bounded orbits around the Earth is investigated. Several different potential schemes related with gravity assists are proposed. A global optimization method, the particle Swarm Optimization (PSO), is employed to obtain the minimal velocity increments for each scheme. With the optimized results, the minimum required velocity increments as well as the mission time are obtained. Results of numerical simulations also indicate that using MGAs is an efficient approach in the capturing mission. The conclusion complies with the analytical result in this paper that a NEA whose velocity relative to the Earth less than 1.8 km/s can be captured by Earth by just one MGA. For other situations, the combination of MGAs and EGAs is better in sense of the required velocity-increments.

  20. Earth-crossing asteroids - Orbital classes, collision rates with earth, and origin

    NASA Technical Reports Server (NTRS)

    Shoemaker, E. M.; Williams, J. G.; Helin, E. F.; Wolfe, R. F.

    1979-01-01

    Asteroids that can intersect the orbit of the earth are discussed, which include Aten asteroids (semimajor axis (a) less than 1 AU, aphelion greater than 0.983 AU), Apollo asteroids (a greater than 1 AU, perihelion less than 1.017 AU), and Amor asteroids (perihelion distance between 1.017 and 1.3 AU). The principal sources of earth-crossing asteroids appear to be extinct comet nuclei and collision fragments from regions in the main asteroid belt. The total population of earth-crossers is estimated at 13,000, of which approximately 8% are Atens, 50% are Apollos, and 40% are Amors,and the present collision rate of such asteroids with the earth is estimated at about 3.5 objects, to absolute magnitude 18, per million years.

  1. Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits

    NASA Technical Reports Server (NTRS)

    Connors, M.; Veillet, C.; Brasser, R.; Wiegert, P.; Chodas, P. W.; Mikkola, S.; Innanen, K.

    2004-01-01

    Newly found asteroid 2003 YN107 is the first and only known current quasi-satellite (QS) of the Earth. Asteroid 2002 AA29 is in a horseshoe orbit (HS) but has periods of QS behavior. Both asteroids closely follow Earth s orbit. 2002 AA29 has inclination i is approximately 11 degrees while for 2003 YN107 i<5 degrees, making the most Earth-like orbit known. 2003 YN107, 2002 AA29, and other Earth-resonant objects in less Earthlike orbits, form an important new class of co-orbital bodies with interesting dynamics and are the best targets for sample return missions to asteroids.

  2. Impact of Ionosphere on GPS-based Precise Orbit Determination of Low Earth Orbiters

    NASA Astrophysics Data System (ADS)

    Arnold, D.; Jaeggi, A.; Beutler, G.; Meyer, U.; Schaer, S.

    2015-12-01

    Deficiencies in geodetic products derived from the orbital trajectories of Low Earth Orbiting (LEO) satellites determined by GPS-based Precise Orbit Determination (POD) were identified in recent years. The precise orbits of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission are, e.g., severely affected by an increased position noise level over the geomagnetic poles and spurious signatures along the Earth's geomagnetic equator (see Fig. 1, which shows the carrier phase residuals of a reduced-dynamic orbit determination for GOCE in m). Such degradations may directly map into the gravity fields recovered from the orbits. They are related to a disturbed GPS signal propagation through the Earth's ionosphere and indicate that the GPS observation model and/or the data pre-processing need to be improved. While GOCE was the first mission where severe ionosphere-related problems became obvious, the GPS-based LEO POD of satellites of the more recent missions Swarm and Sentinel-1A turn out to be affected, as well. We characterize the stochastic and systematic behavior of the ionosphere by analyzing GPS data collected by the POD antennas of various LEO satellites covering a broad altitude range (e.g., GRACE, GOCE and Swarm) and for periods covering significant parts of an entire solar cycle, which probe substantially different ionosphere conditions. The information may provide the basis for improvements of data pre-processing to cope with the ionosphere-induced problems of LEO POD. The performance of cycle slip detection can, e.g., be degraded by large changes of ionospheric refraction from one measurement epoch to the next. Geographically resolved information on the stochastic properties of the ionosphere above the LEOs provide more realistic threshold values for cycle slip detection algorithms. Removing GPS data showing large ionospheric variations is a crude method to mitigate the ionosphere-induced artifacts in orbit and gravity field products

  3. Bringing the environment down to earth.

    PubMed

    Reinhardt, F L

    1999-01-01

    The debate on business and the environment has typically been framed in simple yes-or-no terms: "Does it pay to be green?" But the environment, like other business issues, requires a more complex approach--one that demands more than such all-or-nothing thinking. Managers need to ask instead, "Under what circumstances do particular kinds of environmental investments deliver returns to shareholders?" This article presents five approaches that managers can take to identify those circumstances and integrate the environment into their business thinking. These approaches will enable companies with the right industry structure, competitive position, and managerial skills to reconcile their responsibility to shareholders with the pressure to be faithful stewards of the earth's resources. Some companies can distance themselves from competitors by differentiating their products and commanding higher prices for them. Others may be able to "manage" their competitors by imposing a set of private regulations or by helping to shape the rules written by government officials. Still others may be able to cut costs and help the environment simultaneously. Almost all can learn to improve their management of risk and thus reduce the outlays associated with accidents, lawsuits, and boycotts. And some companies may even be able to make systemic changes that will redefine competition in their markets. All five approaches can help managers bring the environment down to earth. And that means bringing the environment back into the fold of business problems and determining when it really pays to be green. PMID:10539206

  4. Low earth orbital atomic oxygen simulation for materials durability evaluation

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1989-01-01

    The erosion yields of numerous materials have been evaluated in low earth orbital space tests. There appears to be three classes of materials: materials of high erosion yield which include most of the hydrocarbon organic materials; materials which either do not react with atomic oxygen or form self-protecting oxides which allow the underlying material to appear durable to atomic oxygen, and materials with low but nonnegligeable erosion yields, such as fluoropolymers. A NASA atomic oxygen effects test program has been established to utilize collective data from a multitude of simulation facilities to promote an understanding of mechanism and erosion yield dependencies. Atomic oxygen protective coatings for Kapton polymide solar array blankets, fiberglass-epoxy composite mast structures, and solar dynamic power system concentrator surfaces have been identified and evaluated under atomic oxygen exposure in RF plasma asher laboratory tests. The control of defect density in protective coatings appears to be the key to the assurance of long-term protection of oxidizable materials in low earth orbit.

  5. Radiation measured with passive dosimeters in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Zhou, D.; Semones, E.; Gaza, R.; Weyland, M.

    begin center Radiation Measured with Passive Dosimeters in Low Earth Orbit end center begin center D Zhou 1 2 E Semones 1 R Gaza 1 2 M Weyland 1 end center begin center 1 Johnson Space Center - NASA 2101 Nasa Road 1 Houston 77058 USA end center begin center 2 Universities Space Research Association 2101 Nasa Parkway Houston 77058 USA end center begin center Abstract end center The linear energy transfer LET of particles in low Earth orbit LEO is extended from sim 0 1 to sim 1000 keV mu m water The best passive dosimeters for the radiation measurement are thermoluminescence dosimeters TLDs or optically stimulated luminescence dosimeters OSLDs for low LET and CR-39 plastic nuclear track detectors PNTDs for high LET Radiation quantities fluence absorbed dose dose equivalent and quality factor were measured with the passive dosimeters composed of TLDs OSLDs and CR-39 PNTDs for STS-114 mission This paper introduces the operation principles for TLDs OSLDs and CR-39 PNTDs describes the method to combine the results measured by TLDs OSLDs and CR-39 PNTDs and presents the results measured by different dosimeters for different LET band and that combined for all LET

  6. Earth-to-Orbit Education Program 'Makes Science Cool'

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this photograph, Jeff Alden (left) and Justin O'Cornor, two middle school students at Lane Middle School in Portland, Oregon are demonstrating their Earth-to-Orbit (ETO) Design Challenge project at NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. Jeff and Justin, who are just a couple of 'typical teens,' have been spending their time tackling some of the same challenges NASA engineers face when designing propulsion systems at MSFC. The ETO Design Challenge is a hands-on educational program, targeted to middle school students, in which students are assigned a project engaging in related design challenges in their classrooms under the supervision of their teachers. The project is valuable because it can be used by any student and any teacher, even those without technical backgrounds. Students in 12 states: Alabama, Arkansas, California, Colorado, Illinois, Missouri, Montana, New York, Ohio, Tennessee, Virginia, and Washington, are taking part in the MSFC's Earth-to-Orbit program. NASA uses such programs to support educational excellence while participating in educational outreach programs through centers around the country. The Oregon students' teacher, Joanne Fluvog, commented, 'the biggest change I've seen is in the students' motivation and their belief in their ability to think.' Both Justin and Jeff said being involved in a real engineering project has made them realize that 'science is cool.'

  7. Earth-to-Orbit Education Program 'Makes Science Cool'

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this photograph, students from all over the country gathered and discussed their Earth-to-Orbit (ETO) Design Challenge project at NASA Marshall Space Flight Center in Huntsville, Alabama. These students who are just 'typical teens,' have been spending their time tackling some of the same challenges NASA engineers face when designing propulsion systems at MSFC. The ETO Design Challenge is a hands-on educational program, targeted to middle school students, in which students are assigned a project engaging in related design challenges in their classrooms under the supervision of their teachers. The project is valuable because it can be used by any student, and any teacher, even those without technical backgrounds. Student in 12 states: Alabama, Arkansas, California, Colorado, Illinois, Missouri, Montana, New York, Ohio, Ternessee, Virginia, and Washington, are taking part in MSFC's Earth-to-Orbit program. NASA uses such programs to support educational excellence while participating in educational outreach programs through centers around the country. One of the students' teachers, Joanne Fluvog, commented, 'the biggest change I've seen is in the students' motivation and their belief in their ability to think.' Justin O'Connor and Jeff Alden, students of Lane Middle School in Portland, Oregon, participated in the ETO program and said being involved in a real engineering project has made them realize that 'science is cool.'

  8. Structures technology project summary: Earth orbiting platforms program area of the space platforms technology program

    NASA Technical Reports Server (NTRS)

    Bush, Harold

    1991-01-01

    Viewgraphs are presented on the structures technology for the Earth orbiting platforms program. The objective of the work is to develop component and system level structural concepts and design methods to enable in-space construction and deployment of large platform structures in low earth orbit (LEO) and geosynchronous orbit (GEO) including primary platform structures, reflectors and antenna, and habitat and storage modules.

  9. Surveying the earth's environment from space - Spectral, areal, temporal coverage trends

    NASA Technical Reports Server (NTRS)

    Nagler, R. G.

    1977-01-01

    Attention is given to various areas of satellite applications to monitoring the earth's environment. These trends primarily concern spectral, areal, and temporal coverage. Various environmental monitors are discussed in terms of derived economic benefits. Several types of remote sensors for earth applications are described, noting spectral channels, resolution cell size, swath width, and data rate. A sample environmental monitoring system is presented which includes five geostationary satellites, and three or four low earth orbit spacecraft

  10. An Earth Orbiting Satellite Service and Repair Facility

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  11. Orbital Drivers of Climate Change on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Zent, A. P.

    Oscillations of orbital elements and spin axis orientation affect the climate of both Earth and Mars by redistributing solar power both latitudinally and seasonally, often resulting in secondary changes in reflected and emitted radiation (radiative forcing). Multiple feedback loops between different climatic elements operate on both planets, with the result that climate response is generally nonlinear with simple changes in solar energy. Both insolation history and geochemical climate proxies can be treated as time series data, and analyzed in terms of component frequencies. The correspondence between frequencies measured in climate proxies and orbital oscillations is the key to relating orbital cause and climatic effect. Discussions of both Earth and Mars focus on the last 5-10 m.y., because this is the period in which the orbital history and geologic record are best understood. The terrestrial climate is an extraordinarily complex system, and a vast amount of data is available for analysis. While the geologic record strongly supports the role of Milankovitch cycles as the underlying cause of glacial cycles, orbitally driven insolation changes alone cannot explain the observations in detail. Early Pleistocene glacial cycles responded linearly to the 41-k.y. oscillations in obliquity. However, over the last 1 m.y., glacial/interglacial oscillations have become more extreme as the climate has cooled. Long cooling intervals marked by an oscillating buildup of ice sheets are now followed by brief, intense periods of warming. At the same time, glacial/interglacial cycles have shifted from 41 k.y. to ~100 k.y. No such changes occurred in the solar forcing due to orbital oscillations. While orbital oscillations still appear to pace glacial cycles, their subtle interplay with ice-sheet dynamics and shifts in ocean circulation have come to dominate the late Pleistocene climate system. In contrast to Earth, the martian climate is ostensibly a much simpler system about which

  12. Small asteroid fragments in earth-crossing orbits

    NASA Astrophysics Data System (ADS)

    Duha, J.; Afonso, G. B.

    2014-10-01

    The meteorite that fell in Chelyabinsk, Russia, naturally made many people think it could be a smaller companion of the Asteroid 2012 DA14, which passed close to Earth on that same day. Some asteroid specialists discarded this hypothesis for two main reasons: The meteorite was too far away from the asteroid, because the collision happened sixteen hours before the asteroid passed close to Earth. Moreover, it was not traveling, similarly to asteroid DA14, from south to north. However the possibility of the meteorite being a companion of the Asteroid 2012 DA14 cannot be completely discarded. The Asteroid 2012 DA14, with a diameter of 45 meters, is very small. It can be considered an asteroids fragment, which is usually accompanied by other smaller fragments, scattered in space, practically in the same orbit and possibly being separated from each other by long distances. Assuming that 2012 DA14 is not an isolated asteroid, but the biggest remaining fragment from a previous impact, we developed a model to study the dynamics of an asteroid fragment, similar to DA14, and its companions, the smaller fragments. This dynamically interesting encounter with planet Earth is addressed and the orbital changes that could explain the Chelyabinsk event are discussed. As a result we find that, there could be a collision of a meteorite before, during, or after the Asteroid 2012 DA14 passing by, the same way that happens with meteorite showers, which can last several days. Therefore, it would be very interesting to look for asteroid fragments also, close to the larger fragments, more easily found.

  13. Surveillance of medium and high Earth orbits using large baseline stereovision

    NASA Astrophysics Data System (ADS)

    Danescu, Radu; Ciurte, Anca; Oniga, Florin; Cristea, Octavian; Dolea, Paul; Dascal, Vlad; Turcu, Vlad; Mircea, Liviu; Moldovan, Dan

    2014-11-01

    The Earth is surrounded by a swarm of satellites and associated debris known as Resident Space Objects (RSOs). All RSOs will orbit the Earth until they reentry into Earth's atmosphere. There are three main RSO categories: Low Earth Orbit (LEO), when the satellite orbits at an altitude below 1 500 km; a Medium Earth Orbit (MEO) for Global Navigation Satellite Systems (GNSS) at an altitude of around 20 000 km, and a Geostationary Earth Orbit (GEO) (also sometimes called the Clarke orbit), for geostationary satellites, at an altitude of 36 000 km. The Geostationary Earth Orbits and the orbits of higher altitude are also known as High Earth Orbits (HEO). Crucial for keeping an eye on RSOs, the Surveillance of Space (SofS) comprises detection, tracking, propagation of orbital parameters, cataloguing and analysis of these objects. This paper presents a large baseline stereovision based approach for detection and ranging of RSO orbiting at medium to high altitudes. Two identical observation systems, consisting of camera, telescope, control computer and GPS receiver are located 37 km apart, and set to observe the same region of the sky. The telescopes are placed on equatorial mounts able to compensate for the Earth's rotation, so that the stars appear stationary in the acquired images, and the satellites will appear as linear streaks. The two cameras are triggered simultaneously. The satellite streaks are detected in each image of the stereo pair using its streak-like appearance against point-like stars, the motion of the streaks between successive frames, and the stereo disparity. The detected satellite pixels are then put into correspondence using the epipolar geometry, and the 3D position of the satellite in the Earth Center, Earth Fixed (ECEF) reference frame is computed using stereo triangulation. Preliminary tests have been performed, for both MEO and HEO orbits. The preliminary results indicate a very high detection rate for MEO orbits, and good detection rate for

  14. Surface and atmosphere parameter maps from earth-orbiting radiometers

    NASA Technical Reports Server (NTRS)

    Gloersen, P.

    1976-01-01

    Earlier studies have shown that an earth-orbiting electrically scanned microwave radiometer (ESMR) is capable of inferring the extent, concentration, and age of sea ice; the extent, concentration, and thickness of lake ice; rainfall rates over oceans; surface wind speeds over open water; particle size distribution in the deep snow cover of continental ice sheets; and soil moisture content in unvegetated fields. Most other features of the surface of the earth and its atmosphere require multispectral imaging techniques to unscramble the combined contributions of the atmosphere and the surface. Multispectral extraction of surface parameters is analyzed on the basis of a pertinent equation in terms of the observed brightness temperature, the emissivity of the surface which depends on wavelength and various parameters, the sensible temperature of the surface, and the total atmospheric opacity which is also wavelength dependent. Implementation of the multispectral technique is examined. Properties of the surface of the earth and its atmosphere to be determined from a scanning multichannel microwave radiometer are tabulated.

  15. An aeronomy mission to investigate the entry and orbiter environment of Mars

    NASA Technical Reports Server (NTRS)

    Brace, Larry H.

    1989-01-01

    The need for an aeronomy mission to Mars as a precursor to a manned Mars mission is discussed. The upper atmosphere and radiation environment of Mars are reviewed, focusing on the implications of the Martian atmosphere for a manned mission. Plans for an aeronomy mission to Mars are described, including the Mars Aeronomy Observer and the Earth/Mars Aeronomy Orbiter.

  16. Hardware in-the-Loop Demonstration of Real-Time Orbit Determination in High Earth Orbits

    NASA Technical Reports Server (NTRS)

    Moreau, Michael; Naasz, Bo; Leitner, Jesse; Carpenter, J. Russell; Gaylor, Dave

    2005-01-01

    This paper presents results from a study conducted at Goddard Space Flight Center (GSFC) to assess the real-time orbit determination accuracy of GPS-based navigation in a number of different high Earth orbital regimes. Measurements collected from a GPS receiver (connected to a GPS radio frequency (RF) signal simulator) were processed in a navigation filter in real-time, and resulting errors in the estimated states were assessed. For the most challenging orbit simulated, a 12 hour Molniya orbit with an apogee of approximately 39,000 km, mean total position and velocity errors were approximately 7 meters and 3 mm/s respectively. The study also makes direct comparisons between the results from the above hardware in-the-loop tests and results obtained by processing GPS measurements generated from software simulations. Care was taken to use the same models and assumptions in the generation of both the real-time and software simulated measurements, in order that the real-time data could be used to help validate the assumptions and models used in the software simulations. The study makes use of the unique capabilities of the Formation Flying Test Bed at GSFC, which provides a capability to interface with different GPS receivers and to produce real-time, filtered orbit solutions even when less than four satellites are visible. The result is a powerful tool for assessing onboard navigation performance in a wide range of orbital regimes, and a test-bed for developing software and procedures for use in real spacecraft applications.

  17. Enhancing the kinematic precise orbit determination of low earth orbiters using GPS receiver clock modelling

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  18. Impact of the ionosphere on GPS-based precise orbit determination of Low Earth Orbiters

    NASA Astrophysics Data System (ADS)

    Arnold, Daniel; Jäggi, Adrian; Meyer, Ulrich; Beutler, Gerhard

    2016-04-01

    GPS-derived kinematic precise Swarm orbits are significantly affected by increased position noise over the geomagnetic poles and spurious signatures along the geomagnetic equator. The latter deficiencies were identified for the first time for the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) mission and are attributed to the distortion of the GPS carrier signal when propagating through portions of the Earth's ionosphere with a large free electron content. Via the GPS-derived kinematic Swarm positions, the spurious signatures along the geomagnetic equator map directly into the derived gravity fields. This was already the case for GOCE and obviously is also true for Swarm. To identify the root cause of the problem, the stochastic and deterministic behavior of the ionosphere is characterized by analyzing data collected by the GPS receivers on various LEO satellites. We compare in particular the performance of the Swarm and the GRACE receivers, because no obvious degradations occur in GRACE orbit and gravity field solutions. Removing GPS data with large ionospheric variations mitigates the ionosphere-induced artifacts in orbits and gravity fields. We illustrate the impact of this measure on the Swarm orbit and gravity field solutions. Making use of the geographically resolved ionosphere characteristics, e.g., to establish better data weighting schemes, results in a better POD performance for LEO satellites.

  19. Colors of extreme exo-Earth environments.

    PubMed

    Hegde, Siddharth; Kaltenegger, Lisa

    2013-01-01

    The search for extrasolar planets has already detected rocky planets and several planetary candidates with minimum masses that are consistent with rocky planets in the habitable zone of their host stars. A low-resolution spectrum in the form of a color-color diagram of an exoplanet is likely to be one of the first post-detection quantities to be measured for the case of direct detection. In this paper, we explore potentially detectable surface features on rocky exoplanets and their connection to, and importance as, a habitat for extremophiles, as known on Earth. Extremophiles provide us with the minimum known envelope of environmental limits for life on our planet. The color of a planet reveals information on its properties, especially for surface features of rocky planets with clear atmospheres. We use filter photometry in the visible as a first step in the characterization of rocky exoplanets to prioritize targets for follow-up spectroscopy. Many surface environments on Earth have characteristic albedos and occupy a different color space in the visible waveband (0.4-0.9 μm) that can be distinguished remotely. These detectable surface features can be linked to the extreme niches that support extremophiles on Earth and provide a link between geomicrobiology and observational astronomy. This paper explores how filter photometry can serve as a first step in characterizing Earth-like exoplanets for an aerobic as well as an anaerobic atmosphere, thereby prioritizing targets to search for atmospheric biosignatures. PMID:23252379

  20. Technology requirements for advanced earth-orbital transportation systems: Summary report. [single stage to orbit vehicles

    NASA Technical Reports Server (NTRS)

    Haefeli, R. C.; Littler, E. G.; Hurley, J. B.; Winter, M. G.

    1977-01-01

    Areas of advanced technology that are either critical or offer significant benefits to the development of future Earth-orbit transportation systems were identified. Technology assessment was based on the application of these technologies to fully reusable, single-state-to-orbit (SSTO) vehicle concepts with horizontal landing capability. Study guidelines included mission requirements similar to space shuttle, an operational capability beginning in 1995, and main propulsion to be advanced hydrogen-fueled rocket engines. The technical and economic feasibility of this class of SSTO concepts were evaluated as well as the comparative features of three operational take-off modes, which were vertical boost, horizontal sled launch, and horizontal take-off with subsequent inflight fueling. Projections of both normal and accelerated technology growth were made. Figures of merit were derived to provide relative rankings of technology areas. The influence of selected accelerated areas on vehicle design and program costs was analyzed by developing near-optimum point designs.

  1. Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space

    NASA Technical Reports Server (NTRS)

    Yu, Wayne

    2016-01-01

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

  2. Optimization of Return Trajectories for Orbital Transfer Vehicle between Earth and Moon

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  3. Three-Dimensional Orbits of Earth Satellites, Including Effects of Earth Oblateness and Atmospheric Rotation

    NASA Technical Reports Server (NTRS)

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

    1958-01-01

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

  4. Extrasolar Giant Planet in Earth-like Orbit

    NASA Astrophysics Data System (ADS)

    1999-07-01

    companion . iota Hor b has an orbital period of 320 days. From this period, the known mass of the central star (1.03 solar masses) and the amplitude of the velocity changes, a mass of at least 2.26 times that of planet Jupiter is deduced for the planet. It revolves around the host star in a somewhat elongated orbit (the eccentricity is 0.16). If it were located in our own solar system, this orbit would stretch from just outside the orbit of Venus (at 117 million km or 0.78 Astronomical Units from the Sun) to just outside the orbit of the Earth (the point farthest from the Sun, at 162 million km or 1.08 Astronomical Units) The new giant planet is thus moving in an orbit not unlike that of the Earth. In fact, of all the planets discovered so far, the orbit of iota Hor b is the most Earth-like. Also, with a spectral type of G0 V , its host star is quite similar to the Sun (G2 V). iota Hor b is, however, at least 720 times more massive than the Earth and it is probably more similar to planet Jupiter in our own solar system. While the radial velocity technique described above only determines a minimum value for the planet's mass, an analysis of the velocity with which the star turns around its own axis suggests that the true mass of iota Hor b is unlikely to be much higher. A difficult case Natural phenomena with periods near one solar year always present a particular challenge to astronomers. This is one of the reasons why it has been necessary to observe the iota Hor system for such a long time to be absolutely sure about the present result. First, special care must be taken to verify that the radial velocity variations found in the data are not an artefact of the Earth's movement around the Sun. In any case, the effect of this movement on the measurements must be accurately accounted for; it reaches about ± 30 km/sec over one year, i.e. much larger than the effect of the new planet. In the present case of iota Hor , this was thoroughly tested and any residual influence of

  5. Spacecraft design project: Low Earth orbit communications satellite

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  6. Aneutronic fusion propulsion for earth-to-orbit and beyond

    SciTech Connect

    Froning, H. David Jr.; Bussard, Robert W.

    1998-01-15

    Previous work by Bussard has indicated that certain aneutronic fusion rocket propulsion systems could enable establishment of self-supporting space colonies throughout the solar system at transportation costs less than one-tenth current costs to place satellites in orbit around earth. This paper shows that such colonization costs would not significantly increase, even if fusion propulsion performance that is significantly less than that estimated by Bussard would cause increase in the masses and flight times of some of the vehicles. Costs for some colonization missions would significantly increase if colonization vehicles could not be used for other space missions. But even under such circumstances, transportation costs would be extraordinarily low compared to those currently envisioned for solar system exploration.

  7. Tracking target objects orbiting earth using satellite-based telescopes

    DOEpatents

    De Vries, Willem H; Olivier, Scot S; Pertica, Alexander J

    2014-10-14

    A system for tracking objects that are in earth orbit via a constellation or network of satellites having imaging devices is provided. An object tracking system includes a ground controller and, for each satellite in the constellation, an onboard controller. The ground controller receives ephemeris information for a target object and directs that ephemeris information be transmitted to the satellites. Each onboard controller receives ephemeris information for a target object, collects images of the target object based on the expected location of the target object at an expected time, identifies actual locations of the target object from the collected images, and identifies a next expected location at a next expected time based on the identified actual locations of the target object. The onboard controller processes the collected image to identify the actual location of the target object and transmits the actual location information to the ground controller.

  8. Precision positioning of earth orbiting remote sensing systems

    NASA Technical Reports Server (NTRS)

    Melbourne, William G.; Yunck, T. P.; Wu, S. C.

    1987-01-01

    Decimeter tracking accuracy is sought for a number of precise earth sensing satellites to be flown in the 1990's. This accuracy can be achieved with techniques which use the Global Positioning System (GPS) in a differential mode. A precisely located global network of GPS ground receivers and a receiver aboard the user satellite are needed, and all techniques simultaneously estimate the user and GPS satellite states. Three basic navigation approaches include classical dynamic, wholly nondynamic, and reduced dynamic or hybrid formulations. The first two are simply special cases of the third, which promises to deliver subdecimeter accuracy for dynamically unpredictable vehicles down to the lowest orbit altitudes. The potential of these techniques for tracking and gravity field recovery will be demonstrated on NASA's Topex satellite beginning in 1991. Applications to the Shuttle, Space Station, and dedicated remote sensing platforms are being pursued.

  9. Relative time and frequency alignment between two low Earth orbiters, GRACE

    NASA Technical Reports Server (NTRS)

    Bertiger, W.; Dunn, C.; Harris, I.; Kruizinga, G.; Romans, L.; Watkins, M.; Wu, S.

    2003-01-01

    The two GRACE (Gravity Recovery and Climate Experiment) spacecraft were launched into a near polar circular orbit around the earth in March of 2002. The two spacecraft serve as test masses to measure the Earth's gravitational field.

  10. Using The Global Positioning System For Earth Orbiter and Deep Space Network

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.; Haines, Bruce J.; Young, Lawrence E.; Dunn, Charles; Srinivasan, Jeff; Sweeney, Dennis; Nandi, Sumita; Spitzmesser, Don

    1994-01-01

    The Global Positioning System (GPS) can play a major role in supporting orbit and trajectory determination for spacecraft in a wide range of applications, including low-Earth, high-earth, and even deep space (interplanetary) tracking.

  11. Controllable ON-OFF adhesion for Earth orbit grappling applications

    NASA Astrophysics Data System (ADS)

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

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

  12. Optical properties of water released in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Gardner, James A., II; Rall, David L.; Trowbridge, Christian A.; Kofsky, Irving L.; Viereck, Rodney A.

    1993-06-01

    Analysis of intensified video photographs of a twilight venting of excess water from the space shuttle showed that the approx. 1 mm diameter stream cavitationally fragments within about 1 m, forming two discrete-particle components and vapor. The images from nearby cameras are dominated by irregular, polydisperse water/ice droplets with sizes comparable with the venting orifice and outward velocity indistinguishable from that of the initially coherent liquid. In contrast the 2 1/2 km-long quasiconical trail imaged from a distant ground station consists of accompanying submicron ice spherules that were produced by partial recondensation of the overexpanded vacuum-evaporated water gas, which are sublimating at rates that we calculated from the measured falloff of axial sunlight-scatter radiance and the energy balance of progressively roughening ice at 329 km altitude; at low latitudes they cool to 180 K in less than 1 s, and their radii transition to the Rayleigh-scattering range in approx. 1 min. The very much larger fragmentation particles come to a slightly higher equilibrium temperature within approx. 2 min, and persist for a few earth orbits. These three components of the vented water (and other high vapor pressure liquids) radiate and scatter earthshine and solar photons, and the orbital-velocity molecules are also excited by collisions with the residual atmospheric gas, overlaying wide-angle contaminating foregrounds on remote optical sensing from onboard.

  13. Direct Data Distribution From Low-Earth Orbit

    NASA Technical Reports Server (NTRS)

    Budinger, James M.; Fujikawa, Gene; Kunath, Richard R.; Nguyen, Nam T.; Romanofsky, Robert R.; Spence, Rodney L.

    1997-01-01

    NASA Lewis Research Center (LeRC) is developing the space and ground segment technologies necessary to demonstrate a direct data distribution (1)3) system for use in space-to-ground communication links from spacecraft in low-Earth orbit (LEO) to strategically located tracking ground terminals. The key space segment technologies include a K-band (19 GHz) MMIC-based transmit phased array antenna, and a multichannel bandwidth- and power-efficient digital encoder/modulate with an aggregate data rate of 622 Mb/s. Along with small (1.8 meter), low-cost tracking terminals on the ground, the D3 system enables affordable distribution of data to the end user or archive facility through interoperability with commercial terrestrial telecommunications networks. The D3 system is applicable to both government and commercial science and communications spacecraft in LEO. The features and benefits of the D3 system concept are described. Starting with typical orbital characteristics, a set of baseline requirements for representative applications is developed, including requirements for onboard storage and tracking terminals, and sample link budgets are presented. Characteristics of the transmit array antenna and digital encoder/modulator are described. The architecture and components of the tracking terminal are described, including technologies for the next generation terminal. Candidate flights of opportunity for risk mitigation and space demonstration of the D3 features are identified.

  14. Shielding distribution for anisotropic radiation in low earth orbit

    SciTech Connect

    Henley, M.W.

    1986-02-01

    The highly directional nature of radiation encountered in low earth orbit (LEO) can be a basis for distributing mass for spacecraft radiation shielding. Trapped (Van Allen) radiation at low altitudes is concentrated within a plane perpendicular to the local geometric field lines. Trapped high-energy protons (which penetrate the relatively thin shielding required for electrons) have a pronounced east-west asymmetry at low altitudes, with the flux from the west much higher than that from the east. By distributing radition shielding mass in response to these anisotropies, spacecraft mass can be reduced, the altitude limits of LEO extended, and the exposure of men and sensitive materials decreased. Geophysical behavior of trapped radiation is reviewed with particular emphasis on the factors responsible for radiation anisotropy. Shielding distribution in response to anisotropic radiation is then explored for consistently oriented spherical and cylindrical spacecraft. The 28.5-deg orbital inclination is considered in detail, with a brief extension of the concepts to other inclinations. These radiation shielding concepts may find near-term application in Space Station design. 21 references.

  15. Satellite Motion Effects on Current Collection in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Zhang, T. X.; Hwang, K. S.; Wu, S. T.; Stone, N. H.; Chang, C. L.; Drobot, A.; Wright, K. H., Jr.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Results from the Tethered Satellite System (TSS) missions unambiguously show that the electrodynamic tether system produced 2 to 3 times the predicted current levels in the tether. The pre-mission predictions were based on the well-known Parker-Murphy (PM) model, which describes the collection of current by an electrically biased satellite in the ionospheric plasma. How the TSS satellite was able to collect 2-3 times the PM current has remained an open question. In the present study, self-consistent potential and motional effects are introduced into the Thompson and Dobrowolny sheath models. As a result, the magnetic field aligned sheath-an essential variable in determining current collection by a satellite-is derived and is shown to be explicitly velocity dependent. The orientation of the satellite's orbital motion relative to the geomagnetic field is also considered in the derivation and a velocity dependent expression for the collected current is obtained. The resulting model provides a realistic treatment of current collection by a satellite in low earth orbit. Moreover, the predictions, using the appropriate parameters for TSS, are in good agreement with the tether currents measured during the TSS-1R mission.

  16. NASA Advanced Concepts Office, Earth-To-Orbit Team Design Process and Tools

    NASA Technical Reports Server (NTRS)

    Waters, Eric D.; Garcia, Jessica; Beers, Benjamin; Philips, Alan; Holt, James B.; Threet, Grady E., Jr.

    2013-01-01

    The Earth to Orbit (ETO) Team of the Advanced Concepts Office (ACO) at NASA Marshal Space Flight Center (MSFC) is considered the preeminent group to go to for prephase A and phase A concept definition. The ACO team has been at the forefront of a multitude of launch vehicle studies determining the future direction of the Agency as a whole due, in part, to their rapid turnaround time in analyzing concepts and their ability to cover broad trade spaces of vehicles in that limited timeframe. Each completed vehicle concept includes a full mass breakdown of each vehicle to tertiary subsystem components, along with a vehicle trajectory analysis to determine optimized payload delivery to specified orbital parameters, flight environments, and delta v capability. Additionally, a structural analysis of the vehicle based on material properties and geometries is performed as well as an analysis to determine the flight loads based on the trajectory outputs. As mentioned, the ACO Earth to Orbit Team prides themselves on their rapid turnaround time and often need to fulfill customer requests within limited schedule or little advanced notice. Due to working in this fast paced environment, the ETO team has developed some finely honed skills and methods to maximize the delivery capability to meet their customer needs. This paper will describe the interfaces between the 3 primary disciplines used in the design process; weights and sizing, trajectory, and structural analysis, as well as the approach each discipline employs to streamline their particular piece of the design process.

  17. Innovations in mission architectures for exploration beyond low Earth orbit

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  18. From Earth to Orbit: An assessment of transportation options

    NASA Technical Reports Server (NTRS)

    Gavin, Joseph G., Jr.; Blond, Edmund; Brill, Yvonne C.; Budiansky, Bernard; Cooper, Robert S.; Demisch, Wolfgang H.; Hawk, Clark W.; Kerrebrock, Jack L.; Lichtenberg, Byron K.; Mager, Artur

    1992-01-01

    The report assesses the requirements, benefits, technological feasibility, and roles of Earth-to-Orbit transportation systems and options that could be developed in support of future national space programs. Transportation requirements, including those for Mission-to-Planet Earth, Space Station Freedom assembly and operation, human exploration of space, space science missions, and other major civil space missions are examined. These requirements are compared with existing, planned, and potential launch capabilities, including expendable launch vehicles (ELV's), the Space Shuttle, the National Launch System (NLS), and new launch options. In addition, the report examines propulsion systems in the context of various launch vehicles. These include the Advanced Solid Rocket Motor (ASRM), the Redesigned Solid Rocket Motor (RSRM), the Solid Rocket Motor Upgrade (SRMU), the Space Shuttle Main Engine (SSME), the Space Transportation Main Engine (STME), existing expendable launch vehicle engines, and liquid-oxygen/hydrocarbon engines. Consideration is given to systems that have been proposed to accomplish the national interests in relatively cost effective ways, with the recognition that safety and reliability contribute to cost-effectiveness. Related resources, including technology, propulsion test facilities, and manufacturing capabilities are also discussed.

  19. Contribution of explosion and future collision fragments to the orbital debris environment

    NASA Technical Reports Server (NTRS)

    Su, S.-Y.; Kessler, D. J.

    1985-01-01

    The time evolution of the near-earth man-made orbital debris environment modeled by numerical simulation is presented in this paper. The model starts with a data base of orbital debris objects which are tracked by the NORAD ground radar system. The current untrackable small objects are assumed to result from explosions and are predicted from data collected from a ground explosion experiment. Future collisions between earth orbiting objects are handled by the Monte Carlo method to simulate the range of collision possibilities that may occur in the real world. The collision fragmentation process between debris objects is calculated using an empirical formula derived from a laboratory spacecraft impact experiment to obtain the number versus size distribution of the newly generated debris population. The evolution of the future space debris environment is compared with the natural meteoroid background for the relative spacecraft penetration hazard.

  20. PLANECHG: Earth orbit to lunar orbit delta V estimation program. User and technical documentation

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The PLANECNG computer program calculates velocities for Earth-to-Mooon and Moon-to-Earth trajectories. The flight to be analyzed originates in a circular orbit of any inclination and altitude about one of the bodies, and culminates in a circular orbit of any inclination and altitude about the other body. An intermedate delta V and plane change occurs at the Lunar Sphere of Influence (SOI), the region where the vehicle is near its lowest velocity in the trajectory, and therefore where it is able to make the plane change with the lowest delta V. A given flight may penetrate the SOI at a number of points. Each point has associated with it a unique set of delta V's and total velocity. The program displays the velocities, in matrix form, for a representative set of SOI penetration points. An SOI point is identified by projecting Lunar latitude and longitude onto the SOI. The points recorded for a given flight are defined by the user, who provides a starting longitude and latitude, and an increment for each. A matrix is built with 10 longitudes forming the columns and 19 latitudes forming the rows. This matrix is presented in six reports, each containing different velocity or node information in the body of the matrix.

  1. The Orbital Distribution of Earth-crossing Asteroids and Meteoroids

    NASA Astrophysics Data System (ADS)

    Benoit, P. H.; Sears, D. W. G.

    1993-07-01

    The relationship between meteorites and Earth-crossing asteroids and between individual meteorites and meteor showers has been the subject of debate for some time. Recently, links have been claimed between certain meteorites and meteoroid complexes [e.g., 1] and it has been suggested that some meteorites are members of orbital "streams" [2]. It is difficult to evaluate these ideas because of the lack of appropriate measureable properties in the meteorites themselves. Cosmic ray exposure ages provide one approach but most cosmogenic nuclides have large halflives and hence generally reflect the long term radiation exposure of the body rather than the short term orbital evolution leading up to Earth impact. Here we use natural thermoluminescence (TL) data to determine the "average" perihelion of ordinary chondrites among the modern falls over periods of time of less than 10^3-10^5 years prior to Earth impact. The level of natural TL of a meteorite (at a given glow curve temperature) is a function of buildup through radiation dose (which, in turn, is a function of depth or "shielding" and external cosmic ray flux) and decay through thermal draining [3]. The shallow TL vs. depth profile observed in lunar cores [4] can, after correction for irradiation geometry, be used to to calculate TL profiles in meteoroid-sized bodies. Our new calculations indicate a range of natural TL of only about 15% in large meteoroid-sized bodies and an even smaller range in smaller bodies. The "half-life" of TL is far greater than the solar/cosmic ray flux cycle and hence variations in the external flux over time are expected to have only very minor effects. It is thus possible to calculate an "irradiation temperature" for a meteorite using its natural TL level, which can be shown through decay calculations to largely reflect the perihelion of the meteoroid body. The time period over which this irradiation temperature is averaged is a function of the temperature (perihelion); the period is

  2. Long-Term Collision Risk Prediction for Low Earth Orbit Satellite Constellations

    NASA Astrophysics Data System (ADS)

    Walker, R.; Stokes, P. H.; Wilkinson, J. E.; Swinerd, G. G.

    2000-07-01

    In the light of recent changes to planned Low Earth Orbit (LEO) satellite constellation designs and enhancements made to the DERA IDES model, we have conducted a new study on long-term debris environment evolution. This includes the collision interactions of constellation systems with the orbital debris environment over the next 50 years. In this new study, we use the IDES model to simulate long-term evolution in four 'business as usual' future traffic scenarios, which differ by the presence and absence of foreseen satellite constellation traffic and debris mitigation measures. The IDES model is capable of taking high spatial resolution snapshots of the debris flux environment at regular time intervals. By accessing these snapshots, the IDES model is able to predict the long-term variation of debris flux incident on a specific target orbit. This technique is harnessed to predict the average debris flux trends for a typical LEO constellation satellite. Furthermore, we estimate the average debris-induced satellite failure rates for a whole constellation system. Finally, we discuss our new findings on the long-term effects of constellations on the debris environment and vice versa.

  3. Orbit determination of highly elliptical Earth orbiters using improved Doppler data-processing modes

    NASA Technical Reports Server (NTRS)

    Estefan, J. A.

    1995-01-01

    A navigation error covariance analysis of four highly elliptical Earth orbits is described, with apogee heights ranging from 20,000 to 76,800 km and perigee heights ranging from 1,000 to 5,000 km. This analysis differs from earlier studies in that improved navigation data-processing modes were used to reduce the radio metric data. For this study, X-band (8.4-GHz) Doppler data were assumed to be acquired from two Deep Space Network radio antennas and reconstructed orbit errors propagated over a single day. Doppler measurements were formulated as total-count phase measurements and compared to the traditional formulation of differenced-count frequency measurements. In addition, an enhanced data-filtering strategy was used, which treated the principal ground system calibration errors affecting the data as filter parameters. Results suggest that a 40- to 60-percent accuracy improvement may be achievable over traditional data-processing modes in reconstructed orbit errors, with a substantial reduction in reconstructed velocity errors at perigee. Historically, this has been a regime in which stringent navigation requirements have been difficult to meet by conventional methods.

  4. NASA's Program to Monitor Orbital Debris in the GEO Belt and the General Problem of Measuring Near-Earth Object Orbits: Similarities and Differences

    NASA Technical Reports Server (NTRS)

    Matney, Mark

    2006-01-01

    One of the goals for NASA s Orbital Debris Program Office has been to accurately characterize the population of debris in the geosynchronous Earth orbit (GEO) environment. Most objects larger than about 1 meter in size are regularly tracked and catalogued by the US Space Surveillance System in the GEO regime. The consequence has been that most large intact GEO objects are tracked, but the vast majority of GEO debris fragments are not. Only in recent years have observations been dedicated to characterize the GEO debris population. NASA s efforts have concentrated on using wide field-of-view telescopes to make complete surveys of the GEO regime to better our statistical understanding of the GEO debris population. These telescopes operate in a staring mode, and only make limited short-arc measurements of the orbits. This information, while limited, allows the possibility of debiasing the observations and constructing statistical distributions of orbits in inclination and ascending node. Recent work suggests that we may be able to use statistical methods to estimate better orbit parameters despite the limited data. Both of these types of studies estimating statistical orbit distributions, and estimating accurate orbits using limited short-arc data have direct analogues in ongoing studies of near-Earth objects (NEO) such as asteroids and comets. This talk will describe the GEO study methods in use and being developed at NASA, and will discuss how such methods may or may not be applicable for NEO studies as well.

  5. Method of delivering lunar generated fluid to earth orbit using an external tank

    NASA Technical Reports Server (NTRS)

    Butterfield, Ansel J. (Inventor); Goslee, John W. (Inventor)

    1992-01-01

    A method and apparatus are provided for delivering lunar generated fluid to Earth orbit from lunar orbit. Transport takes place in an external tank of a shuttle which has been suitably outfitted in Earth orbit for reusable travel between Earth orbit and a lunar orbit. The outfitting of the external tank includes the adding of an engine, an electrical system, a communication system, a guidance system, an aerobraking device, and a plurality of interconnected fluid storage tanks to the hydrogen and oxygen tanks of the external tank. The external tank is then propelled to lunar orbit the first time using Earth-based propellant. In lunar orbit, the storage tanks are filled with the lunar generated fluid with the remainder tank volumes filled with lunar generated liquid oxygen and hydrogen which serve as propellants for returning the tank to Earth orbit where the fluid is off-loaded. The remaining lunar generated oxygen and hydrogen is then sufficient to return the external tank to lunar orbit so that a subsequent cycle of fluid delivery is repeated. A space station in a higher Earth orbit is preferably used to outfit the external tank, and a lunar node in lunar orbit is used to store and transfer the fluid and liquid oxygen and hydrogen to the external tank. The lunar generated fluid is preferably .sup.3 He.

  6. On possibility of minor body's capture to a satellite orbit before collision with Earth

    NASA Astrophysics Data System (ADS)

    Rosaev, A. E.

    2002-11-01

    In the context of the asteroid's danger problem, the determination of potentially the most dangerous orbits - the orbits of collision with the Earth - has a significant interest. One kind of orbit of collision is related with Lagrangian libration solution for the three body problem. It is known, that possible (temporary) capture to a satellite orbit from orbit near libration point. In case captured orbit has large inclination, it has very fast eccentricity evolution (increasing), leads to inevitable collision. It is not excepted, that object, caused ecological catastrophe 40 mln. years ago, and object push with the Earth on the border Mesozoic and Cenozoic era before the collision were move on of the Earth's satellite orbit. The example of this kind of orbit of collision is presented in this work.

  7. Acquisition/expulsion system for earth orbital propulsion system study. Volume 5: Earth storable design

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A comprehensive analysis and parametric design effort was conducted under the earth-storable phase of the program. Passive Acquisition/expulsion system concepts were evaluated for a reusable Orbital Maneuvering System (OMS) application. The passive surface tension technique for providing gas free liquid on demand was superior to other propellant acquisition methods. Systems using fine mesh screens can provide the requisite stability and satisfy OMS mission requirements. Both fine mesh screen liner and trap systems were given detailed consideration in the parametric design, and trap systems were selected for this particular application. These systems are compatible with the 100- to 500-manned mission reuse requirements.

  8. Mass driver retrievals of earth-approaching asteroids. [earth orbit capture for mining purposes

    NASA Technical Reports Server (NTRS)

    Oleary, B.

    1977-01-01

    Mass driver tugs can be designed to move Apollo and Amor asteroids at opportunities of low velocity increment to the vicinity of the earth. The cost of transferring asteroids through a velocity interval of 3 km/sec by mass driver is about 16 cents per kilogram amortized over 10 years, about ten times less than that required to retrieve lunar resources during the early phases of a program of space manufacturing. About 22 per cent of a 200-meter diameter asteroid could be transferred to high earth orbit by an automated 100 megawatt solar-powered mass driver in a period of five years for a cost of approximately $1 billion. Estimates of the total investment of a space manufacturing program could be reduced twofold by using asteroidal instead of lunar resources; such a program could begin several years sooner with minimal concurrent development if asteroidal search programs and mass driver development are immediately accelerated.

  9. Infrared near-Earth-object survey modeling for observatories interior to the Earth's orbit

    NASA Astrophysics Data System (ADS)

    Buie, M.

    2014-07-01

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

  10. Ballistic design of transfer trajectories from artificial-satellite earth orbit to halo orbit in the neighborhood of the L 2 point of the Sun-Earth system

    NASA Astrophysics Data System (ADS)

    Il'in, I. S.; Zaslavsky, G. S.; Lavrenov, S. M.; Sazonov, V. V.; Stepanyantz, V. A.; Tuchin, A. G.; Tuchin, D. A.; Yaroshevsky, V. S.

    2014-11-01

    The paper considers the ballistic design of spacecraft (SC) transfer to the neighborhood of the L 2 point and subsequent entry of the SC into the halo orbit. Trajectory calculations of one-impulse Earth-halo orbit transfers with and without using a lunar gravitational maneuver are presented. For the calculation of one-impulse trajectories of Earth-halo-orbit transfers, an algorithm for constructing initial approximations is applied. These approximations are constructed by calculating and analyzing the isolines as a function of two variables. This function is represented by the pericenter height of the outgoing orbit over the Earth's surface. The arguments of the function are special parameters that characterize the halo orbit. The mentioned algorithm allows one to obtain halo orbits with specified geometrical characteristics both in the ecliptic plane, and in the plane orthogonal to it. The estimates of the characteristic velocity expenses for maintaining SC in the selected halo orbit are obtained. The described technique was used to search for working orbits of the Spectr-RG and Millimetron spacecraft. Examples of orbits obtained are presented.

  11. EURECA orbits above the Earth's surface prior to STS-57 OV-105 RMS capture

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Backdropped against open ocean waters, the European Retrievable Carrier (EURECA) spacecraft, with solar array (SA) panels folded flat against its sides, approaches Endeavour, Orbiter Vehicle (OV) 105, on flight day five. Later, the remote manipulator system (RMS) end effector was used to 'capture' the spacecraft. After ten days in Earth orbit, the crew returned to Earth, bringing EURECA home.

  12. A low earth orbit dynamic model for the proton anisotropy validation

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.

    2011-11-01

    Ionizing radiation measurements at low earth orbit (LEO) form the ideal tool for the experimental validation of radiation environmental models, nuclear transport code algorithms and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) have provided vital information impacting both the environmental models and the nuclear transport code development by requiring dynamic models of the LEO environment. Previous studies using computer aided design (CAD) models of the international space station (ISS) have demonstrated that the dosimetric prediction for a spacecraft at LEO requires the description of an environmental model with accurate anisotropic as well as dynamic behavior. This paper describes such a model for the trapped proton. The described model is a component of a suite of codes collectively named GEORAD (GEOmagnetic RADiation) which computes cutoff rigidity, trapped proton and trapped electron environments. The web version of GEORAD is named OLTARIS (On-line Tool for the Assessment of Radiation in Space). GEORAD suite is applicable to radiation environment prediction at LEO, medium earth orbit (MEO) and geosynchronous earth orbit (GEO) at quiet solar periods. GEORAD interest is in the study of long term effect of the trapped environment and therefore it does not account for any short term external field contribution due to solar activity. With the concentration of the paper on the LEO protons only, the paper presents the validation of the trapped proton model within GEORAD with reported measurements from the compact environment anomaly sensor (CEASE) science instrument package, flown onboard the tri-service experiment-5 (TSX-5) satellite during the period of June 2000 to July 2006. The spin stabilized satellite was flown in a 410 × 1710 km, 69° inclination elliptical orbit, allowing it to be exposed to a broad range of the LEO regime. The paper puts particular emphasize on the validation of the

  13. Astronaut radiation exposure in low-earth orbit. Part 1. Galactic cosmic radiation

    SciTech Connect

    Letaw, J.R.

    1988-03-31

    In recent years, there has been increasing concern about the radiation doses that will be suffered by astronauts on present-day and future space missions. In order to characterize radiation exposure risks on space missions one requires models of space-radiation environments, codes for transporting the components of ionizing radiation, and procedures for assessing radiation risks of a given exposure. To verify their accuracy, predictions based on these transport results must then be compared with existing dosimetry data. Linear energy transfer (LET) spectra, absorbed dose, and dose equivalent from galactic cosmic radiation and its fragments are presented for four, representative low-earth orbit configurations. The orbits include a high (STS-5IJ) and low (STS-61C) altitude, low-inclination (28.5 degs) flight; a high inclination (49.5 degs) flight (STS-51F); and a polar flight. Results are compared with computations for an exo-magnetospheric flight.

  14. An Analysis of Recent Major Breakups in he Low Earth Orbit Region

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Anz-Meador, P. D.

    2010-01-01

    Of the 190 known satellite breakups between 1961 and 2006, only one generated more than 500 cataloged fragments. The event was the explosion of the Pegasus Hydrazine Auxiliary Propulsion System in 1996, adding 713 fragments to the U.S. Satellite Catalog. Since the beginning of 2007; however, the near-Earth environment has been subjected to several major breakups, including the Fengyun-1C anti-satellite test and the explosion of Briz-M in 2007, the unusual breakup of Cosmos 2421 in 2008, and the collision between Iridium 33 and Cosmos 2251 in 2009. Combined, these events added more than 5000 large (> or equal 10 cm) fragments to the environment. Detailed analysis of the radar cross section measurements and orbit histories of the fragments from these major events reveals several unusual characteristics in their size and area-to-mass ratio distributions. The characteristics could be related to the material composition of the parent vehicles, the nature of the breakup, and the composition and physical property of the fragments. In addition, the majority of these fragments are expected to remain in orbit for at least decades. Their long-term impact to the environment is analyzed using the NASA orbital debris evolutionary model, LEGEND. Descriptions of these analyses and a summary are included in this paper.

  15. LEOrbit: A program to calculate parameters relevant to modeling Low Earth Orbit spacecraft-plasma interaction

    NASA Astrophysics Data System (ADS)

    Marchand, R.; Purschke, D.; Samson, J.

    2013-03-01

    Understanding the physics of interaction between satellites and the space environment is essential in planning and exploiting space missions. Several computer models have been developed over the years to study this interaction. In all cases, simulations are carried out in the reference frame of the spacecraft and effects such as charging, the formation of electrostatic sheaths and wakes are calculated for given conditions of the space environment. In this paper we present a program used to compute magnetic fields and a number of space plasma and space environment parameters relevant to Low Earth Orbits (LEO) spacecraft-plasma interaction modeling. Magnetic fields are obtained from the International Geophysical Reference Field (IGRF) and plasma parameters are obtained from the International Reference Ionosphere (IRI) model. All parameters are computed in the spacecraft frame of reference as a function of its six Keplerian elements. They are presented in a format that can be used directly in most spacecraft-plasma interaction models. Catalogue identifier: AENY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 270308 No. of bytes in distributed program, including test data, etc.: 2323222 Distribution format: tar.gz Programming language: FORTRAN 90. Computer: Non specific. Operating system: Non specific. RAM: 7.1 MB Classification: 19, 4.14. External routines: IRI, IGRF (included in the package). Nature of problem: Compute magnetic field components, direction of the sun, sun visibility factor and approximate plasma parameters in the reference frame of a Low Earth Orbit satellite. Solution method: Orbit integration, calls to IGRF and IRI libraries and transformation of coordinates from geocentric to spacecraft

  16. A Free-Return Earth-Moon Cycler Orbit for an Interplanetary Cruise Ship

    NASA Technical Reports Server (NTRS)

    Genova, Anthony L.; Aldrin, Buzz

    2015-01-01

    A periodic circumlunar orbit is presented that can be used by an interplanetary cruise ship for regular travel between Earth and the Moon. This Earth-Moon cycler orbit was revealed by introducing solar gravity and modest phasing maneuvers (average of 39 m/s per month) which yields close-Earth encounters every 7 or 10 days. Lunar encounters occur every 26 days and offer the chance for a smaller craft to depart the cycler and enter lunar orbit, or head for a Lagrange point (e.g., EM-L2 halo orbit), distant retrograde orbit (DRO), or interplanetary destination such as a near-Earth object (NEO) or Mars. Additionally, return-to-Earth abort options are available from many points along the cycling trajectory.

  17. Circumlunar Free-Return Cycler Orbits for a Manned Earth-Moon Space Station

    NASA Technical Reports Server (NTRS)

    Genova, Anthony L.; Aldrin, Buzz

    2015-01-01

    Multiple free-return circumlunar cycler orbits were designed to allow regular travel between the Earth and Moon by a manned space station. The presented cycler orbits contain circumlunar free-return "figure-8" segments and yield lunar encounters every month. Smaller space "taxi" vehicles can rendezvous with (and depart from) the cycling Earth-Moon space station to enter lunar orbit (and/or land on the lunar surface), return to Earth, or reach destinations including Earth-Moon L1 and L2 halo orbits, near-Earth objects (NEOs), Venus, and Mars. To assess the practicality of the selected orbits, relevant cycler characteristics (including (Delta)V maintenance requirements) are presented and compared.

  18. Probable Rotation States of Rocket Bodies in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  19. Design Concepts for a Small Space-Based GEO Relay Satellite for Missions Between Low Earth and near Earth Orbits

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.; Warner, Joseph D.; Oleson, Steven; Schier, James

    2014-01-01

    the number of links looking above and below GEO; the detailed design of a GEO SSBS spacecraft bus and its accommodation of the communication payload, and a summary of the trade study that resulted in the selection of the Falcon 9 launch vehicle to deploy the SSBS and its impact on cost reductions per satellite. ======================================================================== Several initiatives have taken place within NASA1 and international space agencies2 to create a human exploration strategy for expanding human presence into the solar system; these initiatives have been driven by multiple factors to benefit Earth. Of the many elements in the strategy one stands out: to send robotic and human missions to destinations beyond Low Earth Orbit (LEO), including cis-lunar space, Near-Earth Asteroids (NEAs), the Moon, and Mars and its moons.3, 4 The time frame for human exploration to various destinations, based on the public information available,1,4 is shown in Figure 1. Advance planning is needed to define how future space communications services will be provided in the new budget environment to meet future space communications needs. The spacecraft for these missions can be dispersed anywhere from below LEO to beyond GEO, and to various destinations within the solar system. NASA's Space Communications and Navigation (SCaN) program office provides communication and tracking services to space missions during launch, in-orbit testing, and operation phases. Currently, SCaN's space networking relay satellites mainly provide services to users below GEO, at Near Earth Orbit (NEO), below LEO, and in deep space. The potential exists for using a space-based relay satellite, located in the vicinity of various solar system destinations, to provide communication space links to missions both below and above its orbit. Such relays can meet the needs of human exploration missions for maximum connectivity to Earth locations and for reduced latency. In the past, several studies

  20. Preliminary Design Considerations for Access and Operations in Earth-Moon L1/L2 Orbits

    NASA Technical Reports Server (NTRS)

    Folta, David C.; Pavlak, Thomas A.; Haapala, Amanda F.; Howell, Kathleen C.

    2013-01-01

    Within the context of manned spaceflight activities, Earth-Moon libration point orbits could support lunar surface operations and serve as staging areas for future missions to near-Earth asteroids and Mars. This investigation examines preliminary design considerations including Earth-Moon L1/L2 libration point orbit selection, transfers, and stationkeeping costs associated with maintaining a spacecraft in the vicinity of L1 or L2 for a specified duration. Existing tools in multi-body trajectory design, dynamical systems theory, and orbit maintenance are leveraged in this analysis to explore end-to-end concepts for manned missions to Earth-Moon libration points.

  1. The international environment UNISPACE '82 and the ITU: A relationship between orbit-spectrum resource allocation and orbital debris

    NASA Technical Reports Server (NTRS)

    Olmstead, D.

    1985-01-01

    The 1985 Space WARC will examine and potentially modify the current geostationary orbit spectrum resource allocation methodology. Discussions in this international political environment could likely associate the geostationary orbital debris issue with the politicized issue of orbit spectrum allocation.

  2. TRAPPED PROTON FLUXES AT LOW EARTH ORBITS MEASURED BY THE PAMELA EXPERIMENT

    SciTech Connect

    Adriani, O.; Bongi, M.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Bruno, A.; Boezio, M.; Bonvicini, V.; Carbone, R.; Bogomolov, E. A.; Bottai, S.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; De Donato, C.; De Santis, C.; De Simone, N.; Felice, V. Di; Castellini, G.; and others

    2015-01-20

    We report an accurate measurement of the geomagnetically trapped proton fluxes for kinetic energy above ∼70 MeV performed by the PAMELA mission at low Earth orbits (350 ÷ 610 km). Data were analyzed in the frame of the adiabatic theory of charged particle motion in the geomagnetic field. Flux properties were investigated in detail, providing a full characterization of the particle radiation in the South Atlantic Anomaly region, including locations, energy spectra, and pitch angle distributions. PAMELA results significantly improve the description of the Earth's radiation environment at low altitudes, placing important constraints on the trapping and interaction processes, and can be used to validate current trapped particle radiation models.

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

    NASA Technical Reports Server (NTRS)

    Marr, G.

    2003-01-01

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

  4. Current and Near-Term Future Measurements of the Orbital Debris Environment at NASA

    NASA Technical Reports Server (NTRS)

    Stansbery, Gene; Liou, J.-C.; Mulrooney, M.; Horstman, M

    2010-01-01

    The NASA Orbital Debris Program Office places great emphasis on obtaining and understanding direct measurements of the orbital debris environment. The Orbital Debris Program Office's environmental models are all based on these measurements. Because OD measurements must cover a very wide range of sizes and altitudes, one technique realistically cannot be used for all measurements. In general, radar measurements have been used for lower altitudes and optical measurements for higher altitude orbits. For very small debris, in situ measurements such as returned spacecraft surfaces are utilized. In addition to receiving information from large debris (> 5-10 cm diameter) from the U.S. Space Surveillance Network, NASA conducts statistical measurements of the debris population for smaller sizes. NASA collects data from the Haystack and Goldstone radars for debris in low Earth orbit as small as 2- 4 mm diameter and from the Michigan Orbital DEbris Survey Telescope for debris near geosynchronous orbit altitude for sizes as small as 30-60 cm diameter. NASA is also currently examining the radiator panel of the Hubble Space Telescope Wide Field Planetary Camera 2 which was exposed to space for 16 years and was recently returned to Earth during the STS- 125 Space Shuttle mission. This paper will give an overview of these on-going measurement programs at NASA as well as discuss progress and plans for new instruments and techniques in the near future.

  5. EUV observation from the Earth-orbiting satellite, EXCEED

    NASA Astrophysics Data System (ADS)

    Yoshioka, K.; Murakami, G.; Yoshikawa, I.; Ueno, M.; Uemizu, K.; Yamazaki, A.

    2010-01-01

    An Earth-orbiting small satellite “EXtreme ultraviolet spectrosCope for ExosphEric Dynamics” (EXCEED) which will be launched in 2012 is under development. The mission will carry out spectroscopic and imaging observation of EUV (Extreme Ultraviolet: 60-145 nm) emissions from tenuous plasmas around the planets (Venus, Mars, Mercury, and Jupiter). It is essential for EUV observation to put on an observing site outside the Earth’s atmosphere to avoid the absorption. It is also essential that the detection efficiency must be very high in order to catch the faint signals from those targets. In this mission, we employ cesium iodide coated microchannel plate as a 2 dimensional photon counting devise which shows 1.5-50 times higher quantum detection efficiency comparing with the bared one. We coat the surface of the grating and entrance mirror with silicon carbides by the chemical vapor deposition method in order to archive the high diffraction efficiency and reflectivity. The whole spectrometer is shielded by the 2 mm thick stainless steel to prevent the contamination caused by the high energy electrons from the inner radiation belt. In this paper, we will introduce the mission overview, its instrument, and their performance.

  6. Laboratory simulation of Low Earth Orbit (LEO) atomic oxygen effects

    NASA Technical Reports Server (NTRS)

    Caledonia, George E.; Krech, Robert H.; Oakes, David B.

    1994-01-01

    A pulsed fast oxygen atom source has been used extensively over the last 7 years to investigate the effects of ambient oxygen atoms impacting materials placed in low Earth orbit. In this period, we irradiated well over 2000 material samples with 8 km/s oxygen atoms generated in our source. Typical irradiance level is 3 x 10(exp 20) O atoms/sq cm although some materials have been irradiated to fluence levels as high as 6 x 10(exp 21) O atoms/sq cm. The operating principles and characteristics of our source are reviewed along with diagnostic and handling procedures appropriate to material testing. Representative data is presented on the velocity dependence of oxygen atom erosion rates (the PSI source provides oxygen atoms tunable over the velocity range of 5 to 12 km/s) as well as the dependence on material temperature. Specific examples of non-linear oxidative effects related to surface contamination and test duration are also be provided.

  7. Neutron measurements in near-Earth orbit with COMPTEL

    NASA Technical Reports Server (NTRS)

    Morris, D. J.; Aarts, H.; Bennett, K.; Lockwood, J. A.; Mcconnell, M. L.; Ryan, J. M.; Schoenfelder, V.; Steinle, H.; Peng, X.

    1995-01-01

    The fast neutron flux in near-Earth orbit has been measured with the COMPTEL instrument on the Compton Gamma Ray Observatory (CGRO). For this measurement one of COMPTEL's seven liquid scintillator modules was used as an uncollimated neutron detector with threshold of 12.8 MeV. The measurements cover a range of 4.8 to 15.5 GV in vertical cutoff rigidity and 3 deg to 177 deg in spacecraft geocenter zenith angle. One of the measurements occurred near the minimum of the deepest Forbush decrease ever observed by ground-level neutron monitors. After correction for solar modulation, the total flux is well fitted by separable functions in rigidity and zenith angle. With the spacecraft pointed near the nadir the flux is consistent with balloon measurements of the atmospheric neutron albedo. The flux varies by about a factor of 4 between the extremes of rigidity and a factor of 2 between the extremes of zenith angle. The effect of the spacecraft mass in shielding the detector from the atmospheric neutron albedo is much more important than its role as a source of additional secondary neutrons. The neutron spectral hardness varies little with rigidity or zenith angle and lies in the range spanned by earlier atmospheric neutron albedo measurements.

  8. Physical Limitations of Nuclear Propulsion for Earth to Orbit

    NASA Technical Reports Server (NTRS)

    Blevins, John A.; Patton, Bruce; Rhys, Noah O.; Schafer, Charles F. (Technical Monitor)

    2001-01-01

    An assessment of current nuclear propulsion technology for application in Earth to Orbit (ETO) missions has been performed. It can be shown that current nuclear thermal rocket motors are not sufficient to provide single stage performance as has been stated by previous studies. Further, when taking a systems level approach, it can be shown that NTRs do not compete well with chemical engines where thrust to weight ratios of greater than I are necessary, except possibly for the hybrid chemical/nuclear LANTR (LOX Augmented Nuclear Thermal Rocket) engine. Also, the ETO mission requires high power reactors and consequently large shielding weights compared to NTR space missions where shadow shielding can be used. In the assessment, a quick look at the conceptual ASPEN vehicle proposed in 1962 in provided. Optimistic NTR designs are considered in the assessment as well as discussion on other conceptual nuclear propulsion systems that have been proposed for ETO. Also, a quick look at the turbulent, convective heat transfer relationships that restrict the exchange of nuclear energy to thermal energy in the working fluid and consequently drive the reactor mass is included.

  9. The Earth System Science Pathfinder Orbiting Carbon Observatory (OCO) Mission

    NASA Technical Reports Server (NTRS)

    Crisp, David

    2003-01-01

    A viewgraph presentation describing the Earth System Science Pathfinder Orbiting Carbon Observatory (OCO) Mission is shown. The contents include: 1) Why CO2?; 2) What Processes Control CO2 Sinks?; 3) OCO Science Team; 4) Space-Based Measurements of CO2; 5) Driving Requirement: Precise, Bias-Free Global Measurements; 6) Making Precise CO2 Measurements from Space; 7) OCO Spatial Sampling Strategy; 8) OCO Observing Modes; 9) Implementation Approach; 10) The OCO Instrument; 11) The OCO Spacecraft; 12) OCO Will Fly in the A-Train; 13) Validation Program Ensures Accuracy and Minimizes Spatially Coherent Biases; 14) Can OCO Provide the Required Precision?; 15) O2 Column Retrievals with Ground-based FTS; 16) X(sub CO2) Retrieval Simulations; 17) Impact of Albedo and Aerosol Uncertainty on X(sub CO2) Retrievals; 18) Carbon Cycle Modeling Studies: Seasonal Cycle; 19) Carbon Cycle Modeling Studies: The North-South Gradient in CO2; 20) Carbon Cycle Modeling Studies: Effect of Diurnal Biases; 21) Project Status and Schedule; and 22) Summary.

  10. Thermodynamic Vent System Test in a Low Earth Orbit Simulation

    NASA Technical Reports Server (NTRS)

    VanOverbeke, Thomas J.

    2004-01-01

    A thermodynamic vent system for a cryogenic nitrogen tank was tested in a vacuum chamber simulating oxygen storage in low earth orbit. The nitrogen tank was surrounded by a cryo-shroud at -40 F. The tank was insulated with two layers of multi-layer insulation. Heat transfer into cryogenic tanks causes phase change and increases tank pressure which must be controlled. A thermodynamic vent system was used to control pressure as the location of vapor is unknown in low gravity and direct venting would be wasteful. The thermodynamic vent system consists of a Joule-Thomson valve and heat exchanger installed on the inlet side of the tank mixer-pump. The combination is used to extract thermal energy from the tank fluid, reducing temperature and ullage pressure. The system was sized so that the tank mixer-pump operated a small fraction of the time to limit motor heating. Initially the mixer used sub-cooled liquid to cool the liquid-vapor interface inducing condensation and pressure reduction. Later, the thermodynamic vent system was used. Pressure cycles were performed until steady-state operation was demonstrated. Three test runs were conducted at tank fills of 97, 80, and 63 percent. Each test was begun with a boil-off test to determine heat transfer into the tank. The lower tank fills had time averaged vent rates very close to steady-state boil-off rates showing the thermodynamic vent system was nearly as efficient as direct venting in normal gravity.

  11. The meaning of desert color in earth orbital photographs

    NASA Technical Reports Server (NTRS)

    El-Baz, F.

    1978-01-01

    The color of desert surfaces as seen in earth orbital photographs is indicative of soil composition. Apollo-Soyuz photographs of the Sturt and Simpson Deserts of Australia confirm that sand grains become redder as the distance from the source increases. Reddening is caused by a thin iron-oxide coating on individual sand grains and can be used, in some cases, to map relative-age zones. Photographs of the Western (Libyan) Desert of Egypt indicate three distinct and nearly parallel color zones that have been correlated in the field with: (1) arable soil composed of quartz, clay, and calcium carbonate particles; (2) relatively active sand with or without sparse vegetation; and (3) relatively inactive sand mixed with dark (desert-varnished) pebbles. The youngest sands are in the form of longitudinal dunes, which are migrating to the south-southeast along the prevailing wind direction. Some of the young dune fields are encroaching on the western boundary of the fertile Nile Valley.

  12. Behavior of amino acids and peptides exposed in Earth orbit

    NASA Astrophysics Data System (ADS)

    Barbier, Bernard; Boillot, François; Chabin, Annie; Venet, Michel; Bure, Corinne; Jacquet, Romain; Bertrand-Urbaniak, Marylène; Brack, André

    2001-08-01

    In order to understand the chemical comportment of organic molecules of prebiotic interest when exposed to space conditions, amino acids, derivatives and peptides where exposed in Earth orbit during the CNES "Perseus-Exobiologie" mission. Dry films of samples were exposed free or associated with mineral powders to vacuum and to solar light down to 120 nm during three months outside the MIR station. After the mission, the remaining products were analyzed with respect of chemical degradation, racemization and polymerization. The analyses revealed a higher sensitivity of amino acids comparatively to peptides. The identification of by-products has allowed determining some photolysis pathways where decarboxylation and decarbonylation were found to be the major chemical reactions for amino acids and peptides, respectively. The study of associated minerals have shown that meteoritic powder was the most efficient to protect samples against UV light. The exposure of different peptides associated to meteorite powder of various thickness have allowed to determine that 5μm films were at least necessary to protect associated organics. Implications for the exogenous origin of organics are discussed.

  13. Earth and Moon encounters by the Galileo Jupiter orbiter

    NASA Technical Reports Server (NTRS)

    Clarke, T. C.

    1988-01-01

    The Galileo Venus-Earth-Earth-Gravity-Assist trajectory to Jupiter is discussed. It includes two encounters from deep space with the Earth and the Earth-Moon system. Fortuitous and unique opportunities therefore exist to observe and study the Earth and Earth's moon during both of these encounters. Given the Galileo science payload, a candidate set of Earth and Moon science objectives is presented. The conditions and constraints of the Earth and Moon encounters, which define the observing opportunity, and which bound the objectives, are reviewed.

  14. Innovative observing strategy and orbit determination for Low Earth Orbit space debris

    NASA Astrophysics Data System (ADS)

    Milani, A.; Farnocchia, D.; Dimare, L.; Rossi, A.; Bernardi, F.

    2012-03-01

    We present the results of a large scale simulation, reproducing the behavior of a data center for the build-up and maintenance of a complete catalog of space debris in the upper part of the Low Earth Orbits (LEOs) region. The purpose is to determine the performances of a network of advanced optical sensors, through the use of the newest correlation and orbit determination algorithms. This network is foreseen for implementation in a Space Situational Awareness system, such as the future European one. The conclusion is that it is possible to use a network of optical sensors to build up a catalog containing more than 98% of the objects with perigee height between 1100 and 2000 km, which would be observable by a reference radar system selected as comparison. It is also possible to maintain such a catalog within the accuracy requirements motivated by collision avoidance, and to detect catastrophic fragmentation events. The obtained results depend upon specific assumptions on the sensor and on the software technologies.

  15. Optical and photometric studies of Earth orbiting small space objects

    NASA Astrophysics Data System (ADS)

    Selim, I. M.; El-Hameed, Afaf M. Abd; Bakhtigaraev, N. S.; Attia, Gamal F.

    2016-03-01

    Variations of light curves for space objects are investigated. Optical observations and photometric measurements for small space debris on highly elliptical orbits (HEO) and geostationary orbits (GEO) are used to determine their orbital parameters. Light curves of small space debris with various area-to-mass ratios and orbital characteristics are discussed. Tracking of some objects shows very rapid brightness variations related to perturbations of the orbital parameters. Changes in brightness and equatorial coordinates of the studied objects are found in observational data. Our results allow improving the accuracy of space debris orbital elements.

  16. Manned Earth Observatory - Possible contributions towards enhanced understanding of the marine environment

    NASA Technical Reports Server (NTRS)

    Gerding, R. B.; Johnson, G. F.; Weidner, D. K.

    1973-01-01

    The Manned Earth Observatory (MEO) study being conducted by TRW under the management of NASA/MSFC will establish the conceptual design of and the mission requirements for an Earth Observation Laboratory that will be flown on Shuttle missions beginning in 1980. MEO offers a variety of unique inroads to improving our understanding of the marine environment. The Shuttle-MEO is a valuable addition to a multi-level multi-disciplinary remote sensing program. The unique attributes of MEO are its experimental flexibility due to man-instrument interaction, its complimentary orbit (intermediate between nonorbital and high-orbital platforms), its high weight and volume capacity, and short duration missions.

  17. Sun-Earth L1 Region Halo-To-Halo Orbit and Halo-To-LisaJous Orbit Transfers

    NASA Technical Reports Server (NTRS)

    Roberts, Craig E.; DeFazio, Robert

    2004-01-01

    Practical techniques for designing transfer trajectories between Libration Point Orbits (LPOs) are presented. Motivation for development of these techniques was provided by a hardware contingency experienced by the Solar Heliospheric Observatory (SOHO), a joint mission of the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) orbiting the L1 point of the Sun-Earth system. A potential solution to the problem involved a transfer from SOHO s periodic halo orbit to a new LPO of substantially different dimensions. Assuming the SOHO halo orbit as the departure orbit, several practical LPO transfer techniques were developed to obtain new Lissajous or periodic halo orbits that satisfy mission requirements and constraints. While not implemented for the SOHO mission, practical LPO transfer techniques were devised that are generally applicable to current and future LPO missions.

  18. Around 1500 near-Earth-asteroid orbits improved via EURONEAR

    NASA Astrophysics Data System (ADS)

    Vaduvescu, O.; Hudin, L.; Birlan, M.; Popescu, M.; Tudorica, A.; Toma, R.

    2014-07-01

    Born in 2006 in Paris, the European Near Earth Asteroids Research project (EURONEAR, euronear.imcce.fr) aims ''to study NEAs and PHAs using existing telescopes available to its network and hopefully in the future some automated dedicated 1--2 m facilities''. Although we believe the first aim is fulfilled, the second was not achieved yet, requiring serious commitment from the European NEA researchers and funding agencies. Mainly using free labor by about 30 students and amateur astronomers (from Romania, Chile, UK, France, etc), the PI backed up by his associates M. Birlan (IMCCE Paris) and J. Licandro (IAC Tenerife) and a few other astronomers of the EURONEAR network having access to a few telescopes are approaching around 1,500 observed NEAs whose orbits were improved based on our astrometric contributions. To achive this milestone, we used two main resources and a total of 15 facilities: i) Observing time obtained at 11 professional 1--4 m class telescopes (Chile, La Palma, France, Germany) plus 3 smaller 30--50 cm educational/public outreach telescopes (Romania and Germany) adding about 1,000 observed NEAs; and ii) astrometry obtained from data mining of 4 major image archives (ESO/MPG WFI, INT WFC, CFHTLS Megacam and Subaru SuprimeCam) adding about 500 NEAs recovered in archival images. Among the highlights, about 100 NEAs, PHAs and VIs were observed, recovered or precovered in archives at their second opposition (up to about 15 years away from discovery) or have their orbital arc much extended, and a few VIs and PHAs were eliminated. Incidentally, about 15,000 positions of almost 2,000 known MBAs were reported (mostly in the INT, ESO/MPG and Blanco large fields). About 40 new (one night) NEO candidates and more than 2,000 (one night) unknown MBAs were reported, including about 150 MBAs credited as EURONEAR discoveries. Based on the INT and Blanco data we derived some statistics about the MBA and NEA population observable with 2m and 4m telescopes, proposing a

  19. The Effects of Orbital Environment on X-ray CCD Performance

    NASA Astrophysics Data System (ADS)

    Grant, Catherine E.; LaMarr, Beverly; Miller, Eric D.; Bautz, Mark W.

    2014-06-01

    X-ray telescopes, such as NASA's Chandra X-ray Observatory and Japan's Suzaku, have flown in space for several decades, however the effects of this hostile environment on sensitive astrophysics instruments are still not completely documented. Both observatories use CCD cameras for imaging spectroscopy of the X-ray sky. The CCDs themselves are similar in design, being fabricated at MIT's Lincoln Laboratory. We compare the on-orbit performance evolution of the Chandra ACIS and Suzaku XIS, to better understand the effect of the radiation environment in low- and high-Earth orbit. After more than a combined twenty years in space, both instruments have suffered performance degradation due to radiation damage, but comparison must take into consideration the operational differences, such as the presence of charge injection and the warmer focal plane temperature of the XIS. The low-Earth orbit of Suzaku has the advantage of a lower and stable particle background during observations, while the Chandra particle background during observations is higher and subject to variations due to the solar cycle and solar storms. This is in contrast to the rate of radiation damage accumulation, which is about four times higher for Suzaku, even after correcting for operational differences. We present models of the particle environments for both Suzaku and Chandra which can explain the apparent discrepancy. While the choice of orbit for future missions is obviously dependent on many factors beyond radiation environment, we hope this study will be useful for better informing that choice.

  20. The Effects of Orbital Environment on X-ray CCD Performance

    NASA Astrophysics Data System (ADS)

    Grant, Catherine E.; LaMarr, Beverly; Miller, Eric D.; Bautz, Mark W.

    2014-08-01

    X-ray telescopes, such as NASA's Chandra X-ray Observatory and Japan's Suzaku, have flown in space for several decades, however the effects of this hostile environment on sensitive astrophysics instruments are still not completely documented. Both observatories use CCD cameras for imaging spectroscopy of the X-ray sky. The CCDs themselves are similar in design, being fabricated at MIT's Lincoln Laboratory. We compare the on-orbit performance evolution of the Chandra ACIS and Suzaku XIS, to better understand the effect of the radiation environment in low- and high-Earth orbit. After more than a combined twenty years in space, both instruments have suffered performance degradation due to radiation damage, but comparison must take into consideration the operational differences, such as the presence of charge injection and the warmer focal plane temperature of the XIS. The low-Earth orbit of Suzaku has the advantage of a lower and stable particle background during observations, while the Chandra particle background during observations is higher and subject to variations due to the solar cycle and solar storms. This is in contrast to the rate of radiation damage accumulation, which is about four times higher for Suzaku, even after correcting for operational differences. We present models of the particle environments for both Suzaku and Chandra which can explain the apparent discrepancy. While the choice of orbit for future missions is obviously dependent on many factors beyond radiation environment, we hope this study will be useful for better informing that choice.

  1. Geomorphology From Earth Orbit - Can it be Done?

    NASA Astrophysics Data System (ADS)

    Pieri, D.; Gillespie, A.; Kargel, J.; Ramsey, M.

    2008-12-01

    High spatial and spectral resolution electromagnetic imaging data from orbit is now routinely used within a variety of earth science disciplines, including geomorphology, to assess the effects and state of dynamic earth surface processes, as well as for basic geological and geographical mapping. Temporal sampling ranges from very frequent (e.g., multiple times per week for MODIS) at coarse spatial scales (e.g., 250m to 1km/pixel) to relatively infrequent (e.g., a few times per year for ASTER, or worse considering cloud cover constraints) at geomorphically very useful spatial scales (e.g., <100m/pixel). Observations include spectrophotometric optical image data at visible and near to mid-infrared wavelengths, precise ground temperature and emissivity observations in thermal infrared bands, and topography measurements using optical and microwave data, the latter typically being among the most directly useful geomorphic observations. While such data are helpful in addressing a variety of basic and applied science problems, including issues related to geologic hazards, and are capable of providing a regional to global context, (e.g., ala Victor Baker's "mega-geomorphology" in Short and Blair, 1986, NASA SP-486) a potential question remains vis-à-vis traditional field techniques, as to whether remote sensing data are ever both necessary and sufficient to completely characterize a problem or whether correlative in situ data are a fundamental requirement to completely specify problems of interest. More likely, the necessary balance between the two is idiosyncratic with respect to any individual problem, especially when considering the range of geomorphic arenas being considered (e.g., volcanology, glacial and periglacial processes, hydrology and fluvial geomorphology, mass wasting, coastal studies, eolian studies, and geomorphology related to climate change). We will explore the strengths and weaknesses of emerging remote sensing techniques and practice with respect to

  2. Effects of Low Earth Orbit on Docking Seal Materials

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  3. G-38, 39 and 40: An artist's exploration of space. [using the space environment to create orbiting sphere configurations

    NASA Technical Reports Server (NTRS)

    Mcshane, J. W.; Coursen, C. D.

    1984-01-01

    Three experiments are described which use space processing technology in the formation of and coating of bubbles and spheres to be orbited as sculptures visible from Earth. In one experiment, a 22,000 m1 sphere is to ride into orbit containing a 15 psi Earth atmosphere. Once in orbit, a controller directs a valve to open, linking the sphere to a vacuum of space. Technologies used in the fabrication of these art forms include vacuum film deposition and large bubble formation in the space environment.

  4. Low-gravity Orbiting Research Laboratory Environment Potential Impact on Space Biology Research

    NASA Technical Reports Server (NTRS)

    Jules, Kenol

    2006-01-01

    One of the major objectives of any orbital space research platform is to provide a quiescent low gravity, preferably a zero gravity environment, to perform fundamental as well as applied research. However, small disturbances exist onboard any low earth orbital research platform. The impact of these disturbances must be taken into account by space research scientists during their research planning, design and data analysis in order to avoid confounding factors in their science results. The reduced gravity environment of an orbiting research platform in low earth orbit is a complex phenomenon. Many factors, among others, such as experiment operations, equipment operation, life support systems and crew activity (if it is a crewed platform), aerodynamic drag, gravity gradient, rotational effects as well as the vehicle structural resonance frequencies (structural modes) contribute to form the overall reduced gravity environment in which space research is performed. The contribution of these small disturbances or accelerations is precisely why the environment is NOT a zero gravity environment, but a reduced acceleration environment. This paper does not discuss other factors such as radiation, electromagnetic interference, thermal and pressure gradient changes, acoustic and CO2 build-up to name a few that affect the space research environment as well, but it focuses solely on the magnitude of the acceleration level found on orbiting research laboratory used by research scientists to conduct space research. For ease of analysis this paper divides the frequency spectrum relevant to most of the space research disciplines into three regimes: a) quasi-steady, b) vibratory and c) transient. The International Space Station is used as an example to illustrate the point. The paper discusses the impact of these three regimes on space biology research and results from space flown experiments are used to illustrate the potential negative impact of these disturbances (accelerations

  5. Conceptual radiometer design studies for Earth observations from low Earth orbit

    NASA Technical Reports Server (NTRS)

    Harrington, Richard F.

    1994-01-01

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

  6. Assessment of the consequences of the Fengyun-1C breakup in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Pardini, Carmen

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

  7. Oxidation-resistant reflective surfaces for solar dynamic power generation in near Earth orbit

    NASA Technical Reports Server (NTRS)

    Gulino, D. A.; Mgf2, Sio2, Al2o3, and si3n4, we

    1986-01-01

    Reflective surfaces for space station power generation systems are required to withstand the atomic oxygen-dominated environment of near Earth orbit. Thin films of platinum and rhodium, which are corrosion resistant reflective metals, have been deposited by ion beam sputter deposition onto various substrate materials. Solar reflectances were then measured as a function of time of exposure to a RF-generated air plasma. Similarly, various protective coating materials, including MgF2, SiO2, Al2O3, and Si3N4, were deposited onto silver-coated substrates and then exposed to the plasma. Analysis of the films both before and after exposure by both ESCA and Auger spectroscopy was also performed. The results indicate that Pt and Rh do not suffer any loss in reflectance over the duration of the tests. Also, each of the coating materials survived the plasma environment. The ESCA and Auger analyses are discussed as well.

  8. Investigation of Teflon FEP Embrittlement on Spacecraft in Low-Earth Orbit

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Banks, Bruce A.

    1997-01-01

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

  9. The Orbital Debris Problem and the Challenges for Environment Remediation

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.

    2013-01-01

    Orbital debris scientists from major international space agencies, including JAXA and NASA, have worked together to predict the trend of the future environment. A summary presentation was given to the United Nations in February 2013. The orbital debris population in LEO will continue to increase. Catastrophic collisions will continue to occur every 5 to 9 years center dot To limit the growth of the future debris population and to better protect future spacecraft, active debris removal, should be considered.

  10. An Instrument Concept for Atmospheric Infrared Sounding from Medium Earth Orbit

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Baron, Richard l.

    2004-01-01

    Medium Earth Orbit (MEO) offers a unique vantage point for atmospheric infrared sounding. The orbit allows the entire globe to be covered each day with one satellite. The orbit is slow enough to allow multiple views of a single target to be made on each pass. this paper discusses the advantages in coverage and revisit rate from MEO for a particular concept for a Medium Earth Orbit Infrared Atmospheric Sounder (MIRIS). The requirements for this instrument in terms of spectral range, spatial resolution, field of view, and calibration are presented as well as the radiometric performance expectations.

  11. Solar eruptions - the effects on the Earth's environment

    NASA Astrophysics Data System (ADS)

    Brekke, P.

    The response of our space environment to the constantly changing Sun is known as "Space Weather". The Solar and Heliospheric Observatory (SOHO) has obtained significant new information about coronal mass ejections (CMEs), the source of the most severe disturbances in the Earth's environment. Most of the time space weather is of little concern in our everyday lives. However, when the space environment is disturbed by the variable outputs of the Sun, technologies that we depend on both in orbit and on the ground can be affected. The increasing deployment of radiation-, current-, and field-sensitive technological systems over the last few decades and the increasing presence of complex systems in space combine to make society more vulnerable to solar-terrestrial disturbances. Thus, our society is much more sensitive to space weather activity today compared to the last solar maximum. By observing the Sun 24 hours per day, SOHO has proved to be an important "space weather watchdog". The importance of real-time monitoring of the Sun will be pointed out and a number of enterprises affected by space weather will be discussed.

  12. Solar Eruptions-the effects on the Earth's environment

    NASA Astrophysics Data System (ADS)

    Brekke, P.

    The response of our space environment to the constantly changing Sun is known as "Space Weather". The Solar and Heliospheric Observatory (SOHO) has obtained significant new information about coronal mass ejections (CME's), the source to the most severe disturbances in the Earth's environment. Most of the time space weather is of little concern in our everyday lives. However, when the space environment is disturbed by the variable outputs of the Sun, technologies that we depend on both in orbit and on the ground can be affected. The increasing deployment of radiation-, current-, and field-sensitive technological systems over the last few decades and the increasing presence of complex systems in space combine to make society more vulnerable to solar-terrestrial disturbances. Thus, our society is much more sensitive to space weather activity today compared to the last solar maximum. By observing the Sun 24 hours per day SOHO has proved to be an important ``space weather watchdog''. The importance of real-time monitoring of the Sun will be pointed out and a number of enterprises affected by space weather will be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  14. Laser propulsion to earth orbit. Has its time come?

    NASA Technical Reports Server (NTRS)

    Kantrowitz, Arthur

    1989-01-01

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

  15. Exobiology experiments for Earth-orbital platforms. [Abstract only

    NASA Technical Reports Server (NTRS)

    Huntington, J. L.; Stratton, D. M.; Scattergood, T. W.; Marshall, J. R.

    1994-01-01

    Low-gravity (microgravity) studies relevant to prebiotic evolution and the history of the biogenic elements (C, H, N, O, P, S) are particularly suited to orbital platforms. Relevant to these topics are phenomena such as gas-particle interactions (e.g., formation of organic aerosols via photolytic reactions) including nucleation, condensation, evaporation, adsorption, and catalytic reactions on surfaces; and, small-particle or grain interactions (e.g., growth of interstellar dust particles and planetesimals) including processes such as aggregation (or coagulation), scavenging, and collisions. Both gas-particle and grain (i.e., dust, crystals, organic aerosols, etc.) interactions studies can benefit from microgravity and are pertinent to studies in the areas of chemical evolution in the solar nebula, the interstellar medium, and planetary atmospheres; growth of planetesimals; and prebiotic evolution. In general, the microgravity environment allows for long duration and controlled simulations of processes occurring in exobiologically significant systems such as Titan's atmosphere, interstellar dust clouds, and the solar nebula in which gas-particle or particle-particle interactions play a significant role.

  16. Essentials for Team Based Rehearsals and the Differences Between Earth Orbiting and Deep Space Missions

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  17. Strategies for plane change of Earth orbits using lunar gravity and derived trajectories of family G

    NASA Astrophysics Data System (ADS)

    de Melo, C. F.; Macau, E. E. N.; Winter, O. C.

    2009-04-01

    The dynamics of the circular restricted three-body Earth-Moon-particle problem predicts the existence of the retrograde periodic orbits around the Lagrangian equilibrium point L1. Such orbits belong to the so-called family G (Broucke, Periodic orbits in the restricted three-body problem with Earth-Moon masses, JPL Technical Report 32-1168, 1968) and starting from them it is possible to define a set of trajectories that form round trip links between the Earth and the Moon. These links occur even with more complex dynamical systems as the complete Sun-Earth-Moon-particle problem. One of the most remarkable properties of these trajectories, observed for the four-body problem, is a meaningful inclination gain when they penetrate into the lunar sphere of influence and accomplish a swing-by with the Moon. This way, when one of these trajectories returns to the proximities of the Earth, it will be in a different orbital plane from its initial Earth orbit. In this work, we present studies that show the possibility of using this property mainly to accomplish transfer maneuvers between two Earth orbits with different altitudes and inclinations, with low cost, taking into account the dynamics of the four-body problem and of the swing-by as well. The results show that it is possible to design a set of nominal transfer trajectories that require Δ V Total less than conventional methods like Hohmann, bi-elliptic and bi-parabolic transfer with plane change.

  18. High Latitude Plasma Electrodynamics and Spacecraft Charging in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Neergaard, Linda; Maurits, Sergei; Hwang, Kai; Suggs, Robert; Kross, Denny (Technical Monitor)

    2000-01-01

    Studies of spacecraft charging events on satellites over an altitude range of 800 km to 1800 km have established that negative potentials of hundreds of volts, or even kilovolts, are possible in low Earth orbit (LEO) if there is: (1) a large flux of energetic electrons (10's of keV); and (2) a depletion in the ambient plasma density (<1 x 10(exp 4)/cu cm). To date, quantitative estimates of the probability of encountering severe spacecraft charging environments for spacecraft in low Earth orbit with inclinations near 51 degrees applicable for the International Space Station (ISS), Mir, and associated vehicles are based solely on the relative probability of the vehicle encountering auroral precipitation. A number of the basic assumptions that have been adopted in previous estimates of the charging probabilities are considered in this paper. It is often assumed that precipitating electron flux measured at altitudes above 800 km can be simply adopted unmodified for the lower altitude ranges. We first examine the variations in the electron energy spectrum due to interactions of the primary auroral electrons with the atmosphere to demonstrate that indeed the spectrum of energetic auroral electrons is not significantly altered for altitudes greater than approximately 300 km. Observations of energetic electron populations at altitudes of >800 km are therefore directly applicable to the 350 km to 450 km altitudes at which Mir and the ISS operate.

  19. The Effect of Low Earth Orbit Atomic Oxygen Exposure on Phenylphosphine Oxide-Containing Polymers

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    2000-01-01

    Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Center (LaRC) and the National Space Development Agency of Japan (NASDA). The thin film samples described herein were part of an atomic oxygen exposure experiment (AOE) and were exposed to primarily atomic oxygen (1 X 1019 atoms/cm2). The thin film samples consisted of three phosphine oxide containing polymers (arylene ether, benzimidazole and imide). Based on post-flight analyses using atomic force microscopy, X-ray photoelectron spectroscopy, and weight loss data, it was found that atomic oxygen exposure of these materials efficiently produces a phosphate layer at the surface of the samples. This layer provides a barrier towards further attack by AO. Consequently, these materials do not exhibit linear erosion rates which is in contrast with most organic polymers. Qualitatively, the results obtained from these analyses compare favorably with those obtained from samples exposed to atomic oxygen and or oxygen plasma in ground based exposure experiments. The results of the low Earth orbit atomic oxygen exposure on these materials will be compared with those of ground based exposure to AO.

  20. A Survey of Radiation Measurements Made Aboard Russian Spacecraft in Low-Earth Orbit

    NASA Technical Reports Server (NTRS)

    Benton, E. R.; Benton, E. V.

    1999-01-01

    The accurate prediction of ionizing radiation exposure in low-Earth orbit is necessary in order to minimize risks to astronauts, spacecraft and instrumentation. To this end, models of the radiation environment, the AP-8 trapped proton model and the AE-8 trapped electron model, have been developed for use by spacecraft designers and mission planners. It has been widely acknowledged for some time now by the space radiation community that these models possess some major shortcomings. Both models cover only a limited trapped particle energy region and predictions at low altitudes are extrapolated from higher altitude data. With the launch of the first components of the International Space Station with numerous constellations of low-Earth orbit communications satellites now being planned and deployed, the inadequacies of these trapped particle models need to be addressed. Efforts are now underway both in the U.S. and in Europe to refine the AP-8 and AE-8 trapped particle models. This report is an attempt to collect a significant fraction of data for use in validation of trapped radiation models at low altitudes.

  1. Results from the GPS Flight Experiment on the High Earth Orbit AMSAT OSCAR-40 Spacecraft

    NASA Technical Reports Server (NTRS)

    Bauer, Frank (Technical Monitor); Moreau, Michael C.; Davis, Edward P.; Carpenter, J. Russell; Kelbel, David; Davis, George W.; Axelrad, Penina

    2002-01-01

    A GPS receiver flying on the High Earth Orbit (HEO) AMSAT-OSCAR 40 (AO-40) spacecraft has been returning GPS observations from high above the altitude of the GPS constellation. AO-40, an amateur radio satellite launched November 16, 2000, is currently in a low inclination, 1000 by 59000 lan altitude orbit. This low-cost experiment utilizes a mid 1990's era, 6-channel, CIA code receiver configured with high gain receiving antennas for tracking above the GPS constellation. The receiver has performed well, despite operating significantly outside of its original design environment. It has regularly returned GPS observations from points all around the orbit, with over ten weeks of GPS tracking data collected to date. Signal to noise levels as high as 48 B-Hz have been recorded near apogee, when the spacecraft was at an altitude of close to 60000 km. GPS side lobe signals have been tracked on several occasions, primarily from Block IIR GPS satellites. Although the receiver has not computed a solution in real-time, point solutions have been computed on the ground using simultaneous measurements from four satellites. This experiment has provided important experience dealing with the many challenges inherent to GPS tracking at high altitudes, and the measurements returned are providing valuable information about the characteristics of GPS signals available for future HE0 users.

  2. A Focused Path to Extend Human Presence Beyond Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Robinson, M. S.

    2015-10-01

    Developing a sustainable long-term architecture to move humans out of low Earth orbit and into the solar system requires a focused path built around a series of achievable objectives within a structured time frame.

  3. A model to compare performance of space and ground network support of low-Earth orbiters

    NASA Technical Reports Server (NTRS)

    Posner, E. C.

    1992-01-01

    This article compares the downlink performance in a gross average sense between space and ground network support of low-Earth orbiters. The purpose is to assess what the demand for DSN support of future small, low-cost missions might be, if data storage for spacecraft becomes reliable enough and small enough to support the storage requirements needed to enable support only a fraction of the time. It is shown that the link advantage of the DSN over space reception in an average sense is enormous for low-Earth orbiters. The much shorter distances needed to communicate with the ground network more than make up for the speedup in data rate needed to compensate for the short contact times with the DSN that low-Earth orbiters have. The result is that more and more requests for DSN-only support of low-Earth orbiters can be expected.

  4. Dust particles from comets and asteroids collected at the Earth's orbit: Parent-daughter relationships

    NASA Technical Reports Server (NTRS)

    Jackson, A. A.; Zook, H. A.

    1991-01-01

    The relative contributions of comets and asteroids to the reservoir of dust in the interplanetary medium is not well known. There are direct observations of dust released from comets and there is evidence to associate the IRAS dust bands with possible collisions of Asteroids in the main belt. It is believed that one may combine lab analysis of the physics and chemistry of captured particles with orbital data in order to identify comet and asteroid parent bodies. It is possible to use the collected orbits of the dust to connect with its source in two ways. One is to consider the long time orbit evolution of the dust under Poynting-Robertson drag. The other is to look at the prompt orbit change of dust from comets onto trajectories that intersect the earth's orbit. In order to characterize the orbits of dust particles evolved over a long period of time, a study of its orbital evolution was undertaken. Various parameters associated with these dust orbits as they cross the Earth's orbit were considered in order to see if one may discriminate between particles evolved from comets and asteroids. The method was to calculate by a numerical procedure the orbits of dust particles after they left their parent bodies. It appears that as the particles pass the Earth's orbit, asteroidal grains and cometary grains can be differentiated on the basis of their measured orbital eccentricities even after much planetary perturbation. Broad parent daughter associations can be made on this basis from measurement of their trajectories intercepted in earth orbit.

  5. Rings of Earth detected by orbital debris radar

    NASA Technical Reports Server (NTRS)

    Goldstein, R.; Randolph, L.

    1990-01-01

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

  6. Rings of earth. [orbiting bands of space debris

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  7. Global communication using a constellation of low earth meridian orbits

    NASA Astrophysics Data System (ADS)

    Oli, P. V. S.; Nagarajan, N.; Rayan, H. R.

    1993-07-01

    The concept of 'meridian orbits' is briefly reviewed. It is shown that, if a satellite in the meridian orbit makes an odd number of revolutions per day, then the satellite passes over the same set of meridians twice a day. Satellites in such orbits pass over the same portion of the sky twice a day and every day. This enables a user to adopt a programmed mode of tracking, thereby avoiding a computational facility for orbit prediction, look angle generation, and auto tracking. A constellation of 38 or more satellites placed in a 1200 km altitude circular orbit is favorable for global communications due to various factors. It is shown that appropriate phasing in right ascension of the ascending node and mean anomaly results in a constellation, wherein each satellite appears over the user's horizon one satellite after another. Visibility and coverage plots are provided to verify the continuous coverage.

  8. Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the Lunar Atmosphere Dust Environment Explorer (LADEE) Spacecraft

    NASA Technical Reports Server (NTRS)

    Genova, Anthony L.; Loucks, Michael; Carrico, John

    2014-01-01

    The purpose of this extended abstract is to present results from a failed lunar-orbit insertion (LOI) maneuver contingency analysis for the Lunar Atmosphere Dust Environment Explorer (LADEE) mission, managed and operated by NASA Ames Research Center in Moffett Field, CA. The LADEE spacecrafts nominal trajectory implemented multiple sub-lunar phasing orbits centered at Earth before eventually reaching the Moon (Fig. 1) where a critical LOI maneuver was to be performed [1,2,3]. If this LOI was missed, the LADEE spacecraft would be on an Earth-escape trajectory, bound for heliocentric space. Although a partial mission recovery is possible from a heliocentric orbit (to be discussed in the full paper), it was found that an escape-prevention maneuver could be performed several days after a hypothetical LOI-miss, allowing a return to the desired science orbit around the Moon without leaving the Earths sphere-of-influence (SOI).

  9. Probable Spin-Orbit Aligned Super-Earth Planet Candidate KOI2138

    NASA Astrophysics Data System (ADS)

    Barnes, Jason W.; Ahlers, Johnathon P.; Seubert, Shayne A.; Relles, Howard M.

    2015-08-01

    We use rotational gravity darkening in the disk of Kepler star KOI-2138 to show that the orbit of 2.1-{R}\\oplus transiting planet candidate KOI-2138.01 has a low projected spin-orbit alignment of λ =1^\\circ +/- 13^\\circ . KOI-2138.01 is just the second super-Earth with a measured spin-orbit alignment after 55 Cancri e, and the first to be aligned. With a 23.55 days orbital period, KOI-2138.01 may represent the tip of a future iceberg of solar-system-like terrestrial planets having intermediate periods and low-inclination circular orbits.

  10. Testbed for development of a DSP-based signal processing subsystem for an Earth-orbiting radar scatterometer

    NASA Technical Reports Server (NTRS)

    Clark, Douglas J.; Lux, James P.; Shirbacheh, Mike

    2002-01-01

    A testbed for evaluation of general-purpose digital signal processors in earth-orbiting radar scatterometers is discussed. Because general purpose DSP represents a departure from previous radar signal processing techniques used on scatterometers, there was a need to demonstrate key elements of the system to verify feasibility for potential future scatterometer instruments. Construction of the testbed also facilitated identification of an appropriate software development environment and the skills mix necessary to perform the work.

  11. Tests of general relativity in earth orbit using a superconducting gravity gradiometer

    NASA Technical Reports Server (NTRS)

    Paik, H. J.

    1989-01-01

    Interesting new tests of general relativity could be performed in earth orbit using a sensitive superconducting gravity gradiometer under development. Two such experiments are discussed here: a null test of the tracelessness of the Riemann tensor and detection of the Lense-Thirring term in the earth's gravity field. The gravity gradient signals in various spacecraft orientations are derived, and dominant error sources in each experimental setting are discussed. The instrument, spacecraft, and orbit requirements imposed by the experiments are derived.

  12. Advanced Earth-to-orbit propulsion technology information, dissemination and research

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1995-01-01

    In this period of performance a conference (The 1994 Conference on Advanced Earth-to-Orbit Propulsion Technology) was organized and implemented by the University of Alabama in Huntsville and held May 15-17 to assemble and disseminate the current information on Advanced Earth-to-Orbit Propulsion Technology. The results were assembled for publication as NASA-CP-3282, Volume 1 and 2 and NASA-CP-3287.

  13. Unstable Resonant Orbits near Earth and Their Applications in Planetary Missions

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.; Lo, Martin W.

    2004-01-01

    This paper explores the uses of planar, simple-periodic symmetrical families of orbits in mission designs in the Earth-Moon system. This classification is defined as the planar periodic orbits that pierce the x-axis in the rotating frame exactly twice per orbit where each piercing is orthogonal to the x-axis. A continuation method has been used to explore several families of this class of orbit in the Earth-Moon restricted three-body system. The invariant manifolds of the unstable orbits in each of these families are then produced and several mission designs are discussed that take advantage of these manifolds. Focus is given to mission designs that implement resonant orbits that periodically fly by the moon.

  14. Space shuttle earth orbital rendezvous targeting techniques for near circular target satellite orbits

    NASA Technical Reports Server (NTRS)

    Deaton, A. W.

    1972-01-01

    The targeting techniques are developed which are required to determine the guidance reference release time of the space shuttle navigation system, the orbital insertion targeting values, and a time line of orbital maneuvers. An extension is made for rendezvous with a target satellite in an elliptical orbit.

  15. A low earth orbit skyhook tether transportation system

    NASA Technical Reports Server (NTRS)

    Penzo, Paul A.

    1988-01-01

    This paper discusses the design concept of a structure, called the Skyhook Tether Transportation System (STTS) which may be used to transport mass to higher or lower orbits or to capture objects from higher or lower orbits. An analysis is presented for the possibility of the STTS to perform the function of transporting masses suborbitally, capturing the objects, and then releasing them to a higher orbit, the GEO, the moon, or for an escape. It is shown that, although the possibility of such a system is limited by the tether strength, even a modest system can yield considerable benefits in propellant savings if it is used in combination with chemical propulsion.

  16. Performance and Comparison of Lithium-Ion Batteries Under Low-Earth-Orbit Mission Profiles

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Smart, Marshall C.; Bugga, Ratnakumar V.; Manzo, Michelle A.; Miller, Thomas B.; Gitzendanner, Rob

    2007-01-01

    The performance of two 28 V, 25 Ah lithium-ion batteries is being evaluated under low-Earth-orbit mission profiles for satellite and orbiter applications. The batteries are undergoing life testing and have achieved over 12,000 cycles to 40 percent depth-of-discharge.

  17. Low Earth Orbit Environmental Durability of Recently Developed Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    2015-01-01

    The Materials International Space Station Experiment provided a means to expose materials and devices to the low Earth orbit environment on the exterior of the International Space Station. By returning the specimens to Earth after flight, the specimens could be evaluated by comparison with pre-flight measurements. One area of continuing interest is thermal control paints and coatings that are applied to exterior surfaces of spacecraft. Though traditional radiator coatings have been available for decades, recent work has focused on new coatings that offer custom deposition or custom optical properties. The custom deposition of interest is plasma spraying and one type of coating recently developed as part of a Small Business Innovative Research effort was designed to be plasma sprayed onto radiator surfaces. The custom optical properties of interest are opposite to those of a typical radiator coating, having a combination of high solar absorptance and low infrared emittance for solar absorber applications, and achieved in practice via a cermet coating. Selected specimens of the plasma sprayed coatings and the solar absorber coating were flown on Materials International Space Station Experiment 7, and were recently returned to Earth for post-flight analyses. For the plasma sprayed coatings in the ram direction, one specimen increased in solar absorptance and one specimen decreased in solar absorptance, while the plasma sprayed coatings in the wake direction changed very little in solar absorptance. For the cermet coating deployed in both the ram and wake directions, the solar absorptance increased. Interestingly, all coatings showed little change in infrared emittance.

  18. The distributions of positions of Minimal Orbit Intersection Distances among Near Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Marčeta, Dušan; Šegan, Stevo

    2012-07-01

    This paper presents the distributions of the positions of the Minimal Orbit Intersection Distances (MOID) among three subgroups of the Near Earth Asteroids (NEAs). This includes 683 Atens, 4185 Apollos and 3538 Amors which makes over 15 millions combinations of the pairs of orbits. The results which are obtained in this analysis show very interesting distributions of positions of the MOIDs and circumstances of close approaches of the asteroids and emphasize influence of different orbital elements on these distributions.

  19. Optical Orbit Determination of a Geosynchronous Earth Orbit Satellite Effected by Baseline Distances between Various Ground-based Tracking Stations

    NASA Astrophysics Data System (ADS)

    Son, Ju Young; Jo, Jung Hyun; Choi, Jin; Kim, Bang-Yeop; Yoon, Joh-Na; Yim, Hong-Suh; Choi, Young-Jun; Park, Sun-Youp; Bae, Young Ho; Roh, Dong-Goo; Park, Jang-Hyun; Kim, Ji-Hye

    2015-09-01

    We estimated the orbit of the Communication, Ocean and Meteorological Satellite (COMS), a Geostationary Earth Orbit (GEO) satellite, through data from actual optical observations using telescopes at the Sobaeksan Optical Astronomy Observatory (SOAO) of the Korea Astronomy and Space Science Institute (KASI), Optical Wide field Patrol (OWL) at KASI, and the Chungbuk National University Observatory (CNUO) from August 1, 2014, to January 13, 2015. The astrometric data of the satellite were extracted from the World Coordinate System (WCS) in the obtained images, and geometrically distorted errors were corrected. To handle the optically observed data, corrections were made for the observation time, light-travel time delay, shutter speed delay, and aberration. For final product, the sequential filter within the Orbit Determination Tool Kit (ODTK) was used for orbit estimation based on the results of optical observation. In addition, a comparative analysis was conducted between the precise orbit from the ephemeris of the COMS maintained by the satellite operator and the results of orbit estimation using optical observation. The orbits estimated in simulation agree with those estimated with actual optical observation data. The error in the results using optical observation data decreased with increasing number of observatories. Our results are useful for optimizing observation data for orbit estimation.

  20. An analytical approach to describe the effects of collisions and explosions in the low Earth orbit

    NASA Astrophysics Data System (ADS)

    Hesselbach, Sebastian; Krag, Holger; Braun, Vitali; Kebschull, Christopher; Radtke, Jonas

    There are several numerical programs to compute and describe the environment of space debris in the low Earth orbit. Often the NASA break-up model is used to calculate the collision and explosion events of objects. To fulfill the requirement of faster analyses, analytical approaches can be derived. To use the NASA break-up model for an analytical approach, several corrective factors are required, due to the fact that there are no individual collision and explosion events. In this paper an analytical approach is presented, which can calculate the resulting fragments in the low Earth orbit, on the basis of collisions and explosions in a predefined period of time. The fragmentation of objects within the model is realized using the NASA break-up model. In this model the low Earth orbit is partitioned into altitude shells. Furthermore all objects and fragments of a population are assigned into different bins on the basis of their orbits' eccentricity and their diameter. Fragments resulting from collisions are calculated by pairing different eccentricity and diameter bins inside every shell. The number of fragments from these pairings is corrected by a specific collision probability. The collision probability consists of an altitude dependent object flux and the number of objects of the paired bins. Fragments from explosions are generated based on a specific explosion probability. Due to past explosion events, a predefined number of explosions have been specified for a period of time. With regard to the fact that all intacts are fragmented, because of the analytical approach, this number of explosions is scaled down, with the total number of intacts, resulting in an individual explosion probability. To distribute the fragments on the altitude shells and the eccentricity bins, the model uses a normal distribution to compute the individual additional velocity. The determining parameter is the area-to-mass ratio of the fragments. The paper concludes with the comparison of

  1. Information services platforms at geosynchronous earth orbit: A requirements analysis

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The potential user requirements for Information Services Platforms at geosynchronous orbits were investigated. A rationale for identifying the corollary system requirements and supporting research and technology needs was provided.

  2. Formation Flying in Earth, Libration, and Distant Retrograde Orbits

    NASA Technical Reports Server (NTRS)

    Folta, David C.

    2004-01-01

    This slide presentation examines the current and future state of formation flying, LEO formations, control strategies for flight in the vicinity of the libration points, and distant retrograde orbit formations. This discussion of LEO formations includes background on perturbation theory/accelerations and LEO formation flying. The discussion of strategies for formation flight in the vicinity of the libration points includes libration missions and natural and controlled libration orbit formations. A reference list is included.

  3. Cosmic Influence on the Sun-Earth Environment

    PubMed Central

    Mukherjee, Saumitra

    2008-01-01

    SOHO satellite data reveals geophysical changes before sudden changes in the Earth's Sun-Earth environment. The influence of extragalactic changes on the Sun as well as the Sun-Earth environment seems to be both periodic and episodic. The periodic changes in terms of solar maxima and minima occur every 11 years, whereas the episodic changes can happen at any time. Episodic changes can be monitored by cosmic ray detectors as a sudden increase or decrease of activity. During these solar and cosmic anomaly periods the environment of the Earth is affected. The Star-Sun-Earth connection has the potential to influence the thermosphere, atmosphere, ionosphere and lithosphere. Initial correlation of the cosmic and Sun-Earth connection has shown the possibility of predicting earthquakes, sudden changes in atmospheric temperatures and erratic rainfall/snowfall patterns.

  4. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

    NASA Technical Reports Server (NTRS)

    Carter, P.; Beach, M. A.

    1993-01-01

    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  5. Sheath effects observed on a 10 meter high voltage panel in simulated low earth orbit plasma

    NASA Technical Reports Server (NTRS)

    Mccox, J. E.; Konradi, A.

    1979-01-01

    A large (1m x 10m) flat surface of conductive material was biased to high voltage (+ or - 3000 V) to simulate the behavior of a large solar array in low earth orbit. The model array was operated in a plasma environment of 1,000 to 1,000,000/cu cm, with sufficient free space around it for the resulting plasma sheaths to develop unimpeded for 5-10 meters into the surrounding plasma. Measurements of the resulting sheath thickness were obtained. The observed thickness varied approximately as V to the 3/4 power and N to the 1/2 power. This effect appears to limit total current leakage from the test array until sheath dimensions exceed about 1 meter. Total leakage current was also measured with the array.

  6. The effects of low earth orbit atomic oxygen on the properties of Polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Hooshangi, Zhila; Hossein Feghhi, Seyed Amir; Saeedzadeh, Rezgar

    2016-02-01

    Polymers are widely used in space systems as the structural materials. The low earth orbit (LEO) space environment includes hazards such as atomic oxygen. Exposure of polymeric materials to atomic oxygen results in destructive effects on the chemical, electrical, thermal, optical and mechanical properties as well as surface degradation. In the present work, the effects of atomic oxygen on the mechanical, thermal, and optical properties of Polytetrafluoroethylene film have been investigated. The atomic oxygen density was calculated by SPENVIS tool. After the atomic oxygen exposure by using radio-frequency (RF) plasma source, the appearance of the samples changed, and the mass of the samples reduced because of outgassing. The results of thermal analysis showed that atomic oxygen flux does not affect thermal degradation of samples regarding TGA diagrams. By increasing the atomic oxygen flux, the amount of absorbance increased showing that atomic oxygen had damaged the surface of Polytetrafluoroethylene, and it had oxidized the surface of the polymer.

  7. Free-falling Crystals: Biological Macromolecular Crystal Growth Studies in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Judge, Russell A.; Snell, E. H.; Pusey, M. L.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Spacecraft orbiting the earth experience a reduced acceleration environment due to being in a state of continuous free-fall. This state colloquially termed microgravity, has produced improved X-ray diffraction quality crystals of biological macromolecules. Improvements in X-ray diffraction resolution (detail) or signal to noise, provide greater detail in the three-dimensional molecular structure providing information about the molecule, how it works, how to improve its function or how to impede it. Greater molecular detail obtained by crystallization in microgravity, has important implications for structural biology. In this article we examine the theories behind macromolecule crystal quality improvement in microgravity using results obtained from studies with the model protein, chicken egg white lysozyme.

  8. An evaluation of radiation damage to solid state components flown in low earth orbit satellites.

    PubMed

    Shin, Myung-Won; Kim, Myung-Hyun

    2004-01-01

    The effects of total ionising radiation dose upon commercial off-the-shelf semiconductors fitted to satellites operating in low Earth orbit (LEO) conditions was evaluated. The evaluation was performed for the Korea Institute of Technology SATellite-1, (KITSAT-1) which was equipped with commercial solid state components. Two approximate calculation models for space radiation shielding were developed. Verification was performed by comparing the results with detailed three-dimensional calculations using the Monte-Carlo method and measured data from KITSAT-1. It was confirmed that the developed approximate models were reliable for satellite shielding calculations. It was also found that commercial semiconductor devices, which were not radiation hardened, could be damaged within their lifetime due to the total ionising dose they are subject to in the LEO environment. To conclude, an intensive shielding analysis should be considered when commercial devices are used. PMID:15103058

  9. Low Earth orbital atomic oxygen and ultraviolet radiation effects on polymers

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.

    1991-01-01

    Because atomic oxygen and solar ultraviolet radiation present in the low earth orbital (LEO) environment can alter the chemistry of polymers resulting in degradation, their effects and mechanisms of degradation must be determined in order to determine the long term durability of polymeric surfaces to be exposed on missions such as Space Station Freedom. The effects of atomic oxygen on polymers which contain protective coatings must also be explored, since unique damage mechanisms can occur in areas where the protective coatings has failed. Mechanisms can be determined by utilizing results from previous LEO missions, by performing ground based LEO simulation tests and analysis, and by carrying out focussed space experiments. A survey is presented of the interactions and possible damage mechanisms for environmental atomic oxygen and UV radiation exposure of polymers commonly used in LEO.

  10. The effect of atomic oxygen on polysiloxane-polyimide for spacecraft applications in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Cooper, Jill M.; Olle, Raymond M.

    1991-01-01

    Polysiloxane-polyimide films are of interest as a replacement for polyimide Kapton in the Space Station Freedom solar array blanket. The blanket provides the structural support for the solar cells as well as providing transport of heat away from the back of the cells. Polyimide Kapton would be an ideal material to use; however, its high rate of degradation due to attack by atomic oxygen in low Earth orbit, at the altitudes Space Station Freedom will fly, is of such magnitude that if left unprotected, the blanket will undergo structural failure in much less than the desired 15 year operating life. Polysiloxane-polyimide is of interest as a replacement material because it should from its own protective silicon dioxide coating upon exposure to atomic oxygen. Mass, optical, and photomicrographic data obtained in the evaluation of the durability of polysiloxane-polyimide to an atomic oxygen environment are presented.

  11. A fully coupled flow simulation around spacecraft in low earth orbit

    NASA Technical Reports Server (NTRS)

    Justiz, C. R.; Sega, R. M.

    1991-01-01

    The primary objective of this investigation is to provide a full flow simulation of a spacecraft in low earth orbit (LEO). Due to the nature of the environment, the simulation includes the highly coupled effects of neutral particle flow, free stream plasma flow, nonequilibrium gas dynamics effects, spacecraft charging and electromagnetic field effects. Emphasis is placed on the near wake phenomenon and will be verified in space by the Wake Shield Facility (WSF) and developed for application to Space Station conditions as well as for other spacecraft. The WSF is a metallic disk-type structure that will provide a controlled space platform for highly accurate measurements. Preliminary results are presented for a full flow around a metallic disk.

  12. A Dynamic/Anisotropic Low Earth Orbit (LEO) Ionizing Radiation Model

    NASA Technical Reports Server (NTRS)

    Badavi, Francis F.; West, Katie J.; Nealy, John E.; Wilson, John W.; Abrahms, Briana L.; Luetke, Nathan J.

    2006-01-01

    The International Space Station (ISS) provides the proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the experimental validation of ionizing radiation environmental models, nuclear transport code algorithms, and nuclear reaction cross sections. Indeed, prior measurements on the Space Transportation System (STS; Shuttle) have provided vital information impacting both the environmental models and the nuclear transport code development by requiring dynamic models of the Low Earth Orbit (LEO) environment. Previous studies using Computer Aided Design (CAD) models of the evolving ISS configurations with Thermo Luminescent Detector (TLD) area monitors, demonstrated that computational dosimetry requires environmental models with accurate non-isotropic as well as dynamic behavior, detailed information on rack loading, and an accurate 6 degree of freedom (DOF) description of ISS trajectory and orientation.

  13. Measuring the Eccentricity of the Earth's Orbit with a Nail and a Piece of Plywood

    ERIC Educational Resources Information Center

    Lahaye, Thierry

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.

    1994-01-01

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

  15. Lessons Learned From Atomic Oxygen Interaction With Spacecraft Materials in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim, K.; Miller, Sharon K.; Waters, Deborah L.

    2008-01-01

    There have been five Materials International Space Station Experiment (MISSE) passive experiment carriers (PECs) (MISSE 1-5) to date that have been launched, exposed in space on the exterior of International Space Station (ISS) and then returned to Earth for analysis. An additional four MISSE PECs (MISSE 6A, 6B, 7A, and 7B) are in various stages of completion. The PECs are two-sided suitcase to size sample carriers that are intended to provide information on the effects of the low Earth orbital environment on a wide variety of materials and components. As a result of post retrieval analyses of the retrieved MISSE 2 experiments and numerous prior space experiments, there have been valuable lessons learned and needs identified that are worthy of being documented so that planning, design, and analysis of future space environment experiments can benefit from the experience in order to maximize the knowledge gained. Some of the lessons learned involve the techniques, concepts, and issues associated with measuring atomic oxygen erosion yields. These are presented along with several issues to be considered when designing experiments, such as the uncertainty in mission duration, scattering and contamination effects on results, and the accuracy of measuring atomic oxygen erosion.

  16. Stationkeeping of the First Earth-Moon Libration Orbiters: The ARTEMIS Mission

    NASA Technical Reports Server (NTRS)

    Folta, David; Woodard, Mark; Cosgrove, D.

    2011-01-01

    Libration point orbits near collinear locations are inherently unstable and must be controlled. For Acceleration Reconnection and Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) Earth-Moon Lissajous orbit operations, stationkeeping is challenging because of short time scales, large orbital eccentricity of the secondary, and solar gravitational and radiation pressure perturbations. ARTEMIS is the first NASA mission continuously controlled at both Earth-Moon L1 and L2 locations and uses a balance of optimization, spacecraft implementation and constraints, and multi-body dynamics. Stationkeeping results are compared to pre-mission research including mode directions.

  17. Scheme of rendezvous mission to lunar orbital station by spacecraft launched from Earth

    NASA Astrophysics Data System (ADS)

    Murtazin, R. F.

    2016-05-01

    In recent years, great experience has been accumulated in manned flight astronautics for rendezvous in near-Earth orbit. During flights of Apollo spacecraft with crews that landed on the surface of the Moon, the problem of docking a landing module launched from the Moon's surface with the Apollo spacecraft's command module in a circumlunar orbit was successfully solved. A return to the Moon declared by leading space agencies requires a scheme for rendezvous of a spacecraft launched from an earth-based cosmodromee with a lunar orbital station. This paper considers some ballistic schemes making it possible to solve this problem with minimum fuel expenditures.

  18. Exobiology in Earth orbit: The results of science workshops held at NASA, Ames Research Center

    NASA Technical Reports Server (NTRS)

    Defrees, D. (Editor); Brownlee, D. (Editor); Tarter, J. (Editor); Usher, D. (Editor); Irvine, W. (Editor); Klein, H. (Editor)

    1989-01-01

    The Workshops on Exobiology in Earth Orbit were held to explore concepts for orbital experiments of exobiological interest and make recommendations on which classes of experiments should be carried out. Various observational and experimental opportunities in Earth orbit are described including those associated with the Space Shuttle laboratories, spacecraft deployed from the Space Shuttle and expendable launch vehicles, the Space Station, and lunar bases. Specific science issues and technology needs are summarized. Finally, a list of recommended experiments in the areas of observational exobiology, cosmic dust collection, and in situ experiments is presented.

  19. Low-Thrust Transfers from Distant Retrograde Orbits to L2 Halo Orbits in the Earth-Moon System

    NASA Technical Reports Server (NTRS)

    Parrish, Nathan L.; Parker, Jeffrey S.; Hughes, Steven P.; Heiligers, Jeannette

    2016-01-01

    This paper presents a study of transfers between distant retrograde orbits (DROs) and L2 halo orbits in the Earth-Moon system that could be flown by a spacecraft with solar electric propulsion (SEP). Two collocation-based optimal control methods are used to optimize these highly-nonlinear transfers: Legendre pseudospectral and Hermite-Simpson. Transfers between DROs and halo orbits using low-thrust propulsion have not been studied previously. This paper offers a study of several families of trajectories, parameterized by the number of orbital revolutions in a synodic frame. Even with a poor initial guess, a method is described to reliably generate families of solutions. The circular restricted 3-body problem (CRTBP) is used throughout the paper so that the results are autonomous and simpler to understand.

  20. Doubly-periodic orbits in the Sun-Earth-Moon system

    NASA Technical Reports Server (NTRS)

    Farohar, R.; Muhonen, D.; Dunham, D.

    1980-01-01

    A series of periodic orbits in the Earth-Moon circular restricted problem of three bodies was found which is ideally suited for exploring the Earth's geomagnetic tail. The mean apsidal motion of the basic highly elliptical Earth orbit was maintained at about one degree per day by a sequence of lunar swingbys, keeping the apogees in the anti-Sun direction. The orbits were periodic in reference frames rotating at both lunar and solar rates. Apogee distances were alternately raised and lowered by the lunar swingby maneuvers. Several categories of these Sun-synchronous double lunar swingby orbits were identified. The strength and flexibility of this trajectory concept was demonstrated with real world simulations.

  1. Mission Analysis Program for Solar Electric Propulsion (MAPSEP). Volume 1: Analytical manual for earth orbital MAPSEP

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An introduction to the MAPSEP organization and a detailed analytical description of all models and algorithms are given. These include trajectory and error covariance propagation methods, orbit determination processes, thrust modeling, and trajectory correction (guidance) schemes. Earth orbital MAPSEP contains the capability of analyzing almost any currently projected low thrust mission from low earth orbit to super synchronous altitudes. Furthermore, MAPSEP is sufficiently flexible to incorporate extended dynamic models, alternate mission strategies, and almost any other system requirement imposed by the user. As in the interplanetary version, earth orbital MAPSEP represents a trade-off between precision modeling and computational speed consistent with defining necessary system requirements. It can be used in feasibility studies as well as in flight operational support. Pertinent operational constraints are available both implicitly and explicitly. However, the reader should be warned that because of program complexity, MAPSEP is only as good as the user and will quickly succumb to faulty user inputs.

  2. Pulsed Plasma Propulsion - Making CubeSat Missions Beyond Low Earth Orbit Possible

    NASA Astrophysics Data System (ADS)

    Northway, P.

    2015-12-01

    As CubeSat missions become more and more popular means of scientific exploration of space, the current direction of interest is to utilize them in areas beyond low earth orbit. The University of Washington CubeSat program focuses on examining possible mission scenarios in addition to technology development and integration. Specifically, we are developing an inert CubeSat propulsion system in the form of a pulsed plasma thruster (PPT) capable of orbit maneuvers. Such a system would allow for missions at the Earth beyond LEO, extended missions at the Moon, and even missions at Europa, when assisted to the Jovian system. We will discuss how starting with a CubeSat design using PPTs for orbital maneuvers, other developing compact technology can be adapted to create a full suite of systems that would meet the requirements for a mission traveling outside low earth orbit.

  3. Low Earth orbit atomic oxygen simulation for durability evaluation of solar reflector surfaces

    NASA Technical Reports Server (NTRS)

    Degroh, Kim K.; Banks, Bruce A.

    1992-01-01

    To evaluate the performance and durability of solar reflector surfaces in the atomic oxygen environment typical of low Earth orbit (LEO), one must expose the reflector surface either directly to LEO or to ground-laboratory atomic oxygen environments. Although actual LEO exposures are most desired, such opportunities are typically scarce, expensive, and of limited duration. As a result, ground-laboratory exposures must be relied upon as the most practical long-term durability evaluation technique. Plasma ashers are widely used as LEO simulation facilities by producing atomic oxygen environments for durability evaluation of potential spacecraft materials. Atomic oxygen arrival differs between ground and space exposure in that plasma asher exposure produces isotropic arrival and space solar tracking produces sweeping arrival. Differences in initial impact reaction probability occur, dependent upon the energy and species existing in these environments. Due to the variations in ground-laboratory and space atomic oxygen, quantification of in-space performance based on plasma asher testing is not straightforward. The various atomic oxygen interactions that can occur with reflector surfaces, such as undercutting in organic substrates at protective coating defect sites, ground-laboratory techniques recommended for evaluating the atomic oxygen durability of reflectors based on asher exposures, and computational techniques which make use of ground-laboratory atomic oxygen exposure to predict in-space LEO durability are addressed.

  4. Space Shuttle Orbiter logistics - Managing in a dynamic environment

    NASA Technical Reports Server (NTRS)

    Renfroe, Michael B.; Bradshaw, Kimberly

    1990-01-01

    The importance and methods of monitoring logistics vital signs, logistics data sources and acquisition, and converting data into useful management information are presented. With the launch and landing site for the Shuttle Orbiter project at the Kennedy Space Center now totally responsible for its own supportability posture, it is imperative that logistics resource requirements and management be continually monitored and reassessed. Detailed graphs and data concerning various aspects of logistics activities including objectives, inventory operating levels, customer environment, and data sources are provided. Finally, some lessons learned from the Shuttle Orbiter project and logistics options which should be considered by other space programs are discussed.

  5. Access to Mars from Earth-Moon Libration Point Orbits:. [Manifold and Direct Options

    NASA Technical Reports Server (NTRS)

    Kakoi, Masaki; Howell, Kathleen C.; Folta, David

    2014-01-01

    This investigation is focused specifically on transfers from Earth-Moon L(sub 1)/L(sub 2) libration point orbits to Mars. Initially, the analysis is based in the circular restricted three-body problem to utilize the framework of the invariant manifolds. Various departure scenarios are compared, including arcs that leverage manifolds associated with the Sun-Earth L(sub 2) orbits as well as non-manifold trajectories. For the manifold options, ballistic transfers from Earth-Moon L(sub 2) libration point orbits to Sun-Earth L(sub 1)/L(sub 2) halo orbits are first computed. This autonomous procedure applies to both departure and arrival between the Earth-Moon and Sun-Earth systems. Departure times in the lunar cycle, amplitudes and types of libration point orbits, manifold selection, and the orientation/location of the surface of section all contribute to produce a variety of options. As the destination planet, the ephemeris position for Mars is employed throughout the analysis. The complete transfer is transitioned to the ephemeris model after the initial design phase. Results for multiple departure/arrival scenarios are compared.

  6. Distant Retrograde Orbits for space-based Near Earth Objects detection

    NASA Astrophysics Data System (ADS)

    Stramacchia, Michele; Colombo, Camilla; Bernelli-Zazzera, Franco

    2016-09-01

    We analyse a concept for the detection of Potentially Hazardous Asteroids (PHAs) from a space-based network of telescopes on retrograde Distant Periodic Orbits. Planar periodic orbits are designed in the Sun-Earth circular restricted three-body problem, starting from initial conditions in the Hill's problem available from the literature. A family of retrograde orbits centred at the Earth is selected as baseline, based on their maximum distance from Earth, larger than the Earth-L2 distance. Indeed, spacecraft on such orbits can detect PHAs incoming from the Sun direction, which could not otherwise be monitored from current Earth-based systems. A trade-off on the orbit amplitude, asteroid diameter to be detected, and the constellation size is performed considering current visible sensor telescope technology. The Chelyabinsk meteor scenario is studied and the potential warning time that could be gained with a space-based survey system with respect to an Earth based-survey system is shown.

  7. Attitude control requirements for an earth-orbital solar electric propulsion stage

    NASA Technical Reports Server (NTRS)

    Oglevie, R. E.; Andrews, P. D.; Jasper, T. P.

    1975-01-01

    Solar Electric Propulsion Stage (SEPS) application in earth orbit requires considerably more maneuvering for thrust vector steering and solar array pointing than planetary missions. Attitude maneuver requirements for geosynchronous and low earth-orbital missions are presented. Situations which result in optimum steering torque requirements exceeding the capability of current SEPS configurations are defined. Sub-optimal steering techniques are defined which reduce the geosynchronous mission torque requirements to acceptable levels with negligible performance penalties. Some low earth-orbital flight regimes with earth shadowing are found to result in much larger torque requirements and impose significant mechanization penalties if serious performance losses are to be avoided. Alternative attitude control mechanization techniques are defined for these cases.

  8. Orbital Properties of the Arecibo Micrometeoroids at Earth Interception

    NASA Astrophysics Data System (ADS)

    Janches, D.; Meisel, D. D.; Mathews, J. D.

    2001-04-01

    Using the Arecibo Observatory (AO) 430-MHz Radar we have developed a Doppler technique to measure very precise micrometeor instantaneous velocities directly from the meteor head echo. In addition, a large number of the observed meteoroids show deceleration. With the velocity, the deceleration, and the assumptions of a spherical shape and a mean micrometeoroid mass density, we have obtained estimates of in-atmosphere particle sizes. The size estimate, the MSIS model atmosphere, and the measured deceleration are used to obtain the meteor extra-atmospheric speeds, assuming these particles undergo little mass-loss prior to and during the time we detect them (Janches et al. 2000b, Icarus145, 53-63). Orbital elements at 1 AU are presented and discussed. These results have not been corrected for perturbation effects such as radiation pressure, Poynting-Robertson drag, attraction by the giant planets, and photoelectric charging effects. So far, over 7700 detections obtained during November 1997 and 3500 during the November 1998 observation campaigns have been analyzed. The observing periods included the Leonids meteor shower, but none of the orbits are recently derived from it. Out of these detections, we present details of over 1500 orbits with eccentricities less than unity. These orbits show (a) a depletion of postperihelion particles with small perihelion distance, suggesting the possibility of collisional and thermal destruction, and (b) an enhancement of particles with perihelia in the zone between Mercury and Venus. Also discussed are 40 β-meteoroids (with radii less than 0.5 μm) dynamically related to the elliptical orbit population with q<0.7 AU. We interpret the latter results on the basis of Poynting-Robertson drag and the electromagnetic resonant effects proposed by G. E. Morfill and E. Grün (1979, Planet. Space Sci.27, 1269-1282). Comparison with previous data sets indicates that most of the AO micrometeoroid orbits are well randomized and that association

  9. Antenna servo design for tracking low-earth-orbiting satellites

    NASA Astrophysics Data System (ADS)

    Gawronski, W.; Mellstrom, J. A.

    1994-11-01

    The upcoming NASA missions will require tracking of low-orbit satellites. As a consequence, NASA antennas will be required to track satellites at higher rates than for the current deep-space missions. This paper investigates servo design issues for the 34-m beam-waveguide antennas that track low-orbit satellites. This includes upgrading the servo with a feedforward loop, monopulse controller design, and tracking error reduction either through proper choice of elevation pinion location or through application of a notch filter or adjustment of the elevation drive amplifier gain. Finally, improvement of the signal-to-noise ratio through averaging of the oversampled monopulse signal is described.

  10. Mission Preparation Program for Exobiological Experiments in Earth Orbit

    NASA Astrophysics Data System (ADS)

    Panitz, Corinna; Reitz, Guenther; Horneck, Gerda; Rabbow, Elke; Rettberg, Petra

    The ESA facilities EXPOSE-R and EXPOSE-E on board of the the International Space Station ISS provide the technology for exposing chemical and biological samples in a controlled manner to outer space parameters, such as high vacuum, intense radiation of galactic and solar origin and microgravity. EXPOSE-E has been attached to the outer balcony of the European Columbus module of the ISS in Febraury 2008 and will stay for about 1 year in space, EXPOSE-R will be attached to the Russian Svezda module of the ISS in fall 2008. The EXPOSE facilities are a further step in the study of the Responses of Organisms to Space Environment (ROSE concortium). The results from the EXPOSE missions will give new insights into the survivability of terrestrial organisms in space and will contribute to the understanding of the organic chemistry processes in space, the biological adaptation strategies to extreme conditions, e.g. on early Earth and Mars, and the distribution of life beyond its planet of origin.To test the compatibility of the different biological and chemical systems and their adaptation to the opportunities and constraints of space conditions a profound ground support program has been developed. It resulted in several experiment verification tests EVTs and an experiment sequence test EST that were conducted in the carefully equipped and monitored planetary and space simulation facilities PSI of the Institute of Aerospace Medicine at DLR in Cologne, Germany. These ground based pre-flight studies allow the investigation of a much wider variety of samples and the selection of the most promising organisms for the flight experiment. The procedure and results of these EVT tests and EST will be presented. These results are an essential prerequisite for the success of the EXPOSE missions and have been done in parallel with the development and construction of the final hardware design of the facility. The results gained during the simulation experiments demonstrated mission

  11. Dynamics of Orbits near 3:1 Resonance in the Earth-Moon System

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  12. Remote Sensing of Earth and Environment

    ERIC Educational Resources Information Center

    Schertler, Ronald J.

    1974-01-01

    Discusses basic principles of remote sensing applications and five areas of the earth resources survey program: agriculture and forestry production; geography, cartography, cultural resources; geology and mineral resources; hydrology and water resources; and oceanography and marine resources. Indicates that information acquisition is the first…

  13. Investigating the Earth and Its Environment

    ERIC Educational Resources Information Center

    Everett, Cheryl; Spear, Robyn

    2008-01-01

    Along with the need to make their curriculum more comprehensive and reflective of the national and state standards, one school district also searched for ways to make students more passionate about learning science. As a result, they developed a new integrated science course that is centered around the environmental and Earth sciences with an…

  14. Safety in earth orbit study. Volume 2: Analysis of hazardous payloads, docking, on-board survivability

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Detailed and supporting analyses are presented of the hazardous payloads, docking, and on-board survivability aspects connected with earth orbital operations of the space shuttle program. The hazards resulting from delivery, deployment, and retrieval of hazardous payloads, and from handling and transport of cargo between orbiter, sortie modules, and space station are identified and analyzed. The safety aspects of shuttle orbiter to modular space station docking includes docking for assembly of space station, normal resupply docking, and emergency docking. Personnel traffic patterns, escape routes, and on-board survivability are analyzed for orbiter with crew and passenger, sortie modules, and modular space station, under normal, emergency, and EVA and IVA operations.

  15. Comprehensive evaluation of attitude and orbit estimation using real earth magnetic field data

    NASA Technical Reports Server (NTRS)

    Deutschmann, Julie; Bar-Itzhack, Itzhack

    1997-01-01

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

  16. Investigation of vehicle reusability for human exploration of Near-Earth Asteroids using Sun-Earth Libration point orbits

    NASA Astrophysics Data System (ADS)

    Zimmer, A. K.

    2013-09-01

    Current plans for human exploration of the solar system envision several missions to Near-Earth Asteroids (NEAs) as stepping stones towards missions to Mars. This research investigates the feasibility of stationing reusable cargo spacecraft, such as habitats, in halo orbits at Sun-Earth Libration points 1 and 2 (L1 and L2) between NEA missions in an effort to reduce mission cost and thus overall campaign cost by lowering the mass required to be launched and the amount of new hardware to be built for each mission. Four example missions to the two currently most promising targets of the known NEA population in the 2025-2030 time frame are chosen. In the mission architecture proposed in this study, the crew vehicle directly commutes between Earth and the asteroid in order to keep mission durations for the crew short. The cargo vehicle departs from a halo orbit, rendezvous with the crew vehicle on the outbound trajectory, and returns to a halo orbit after the mission. Manifold trajectories of halo orbits in the northern and southern halo orbit family at L1 and L2 are considered for the transfer of the cargo vehicle to and from the interplanetary trajectory and the total Δv required for this transfer is minimized. This Δv is found to range from a few meters per second to hundreds of meters per second, depending on the specific energy and inclination of the interplanetary trajectory. These results show the great potential of the utilization of Sun-Earth Libration point orbits for enabling vehicle reusability, thus lowering the cost of human exploration missions.

  17. Low-Thrust Transfers from Distant Retrograde Orbits to L2 Halo Orbits in the Earth-Moon System

    NASA Technical Reports Server (NTRS)

    Parrish, Nathan L.; Parker, Jeffrey S.; Hughes, Steven P.; Heiligers, Jennette

    2016-01-01

    Enable future missions Any mission to a DRO or halo orbit could benefit from the capability to transfer between these orbits Chemical propulsion could be used for these transfers, but at high propellant cost Fill gaps in knowledge A variety of transfers using SEP or solar sails have been studied for the Earth-Moon system Most results in literature study a single transfer This is a step toward understanding the wide array of types of transfers available in an N-body force model.

  18. Biofilms On Orbit and On Earth: Current Methods, Future Needs

    NASA Technical Reports Server (NTRS)

    Vega, Leticia

    2013-01-01

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

  19. Autonomous guidance & control of Earth-orbiting formation flying spacecraft

    NASA Astrophysics Data System (ADS)

    Hamel, Jean-Francois

    Formation flying of spacecraft has gained a lot of interest within the engineering and scientific community in recent years. However, formation flying leads to an increased complexity of the guidance and control system, whose complexity grows rapidly with the number of spacecraft in the formation. Moreover, there is an increasing need for autonomy to decrease the cost of ground support since ground support operations are often a non-negligible part of the cost of a mission. Therefore, a formation flying guidance and control system needs to perform autonomous decisions and trade-offs in real-time to decrease the number of tasks that need to be performed by the ground segment and make formation flying affordable. This work presents the development of analytical formation flying guidance and control laws for autonomous on-board applications. Firstly, an analytical model of relative motion for elliptical and perturbed reference orbits is developed. This model is solely based on the initial orbit elements of the reference trajectory and can predict the relative motion of any spacecraft orbiting close to the reference trajectory, taking into account the secular drift caused by the J2 perturbation. Secondly, a new tool, the Fuel-Equivalent Space, is presented. The Fuel-Equivalent Space theory maps the relative orbit elements into a mathematical space where similar displacements on any axis is similar in terms of maneuvering fuel cost, therefore translating the minimum fuel problem into a simple distance minimization problem. Then, a neighbouring optimum feedback control law is developed. This feedback control law makes use of the optimal control theory to yield a semi-analytical controller that guarantees near-optimal maneuvering for any of the spacecraft orbiting close to the reference trajectory. Finally, it is shown that all these three new developments can be tied in together with simple analytical guidance laws to yield a fully autonomous guidance and control

  20. Preliminary Attempts to Connect Ocean Reflected GNSS Signals Detected From Low Earth Orbit With Sea Winds

    NASA Astrophysics Data System (ADS)

    Gleason, S.; Sun, Y.; Gommenginger, C.; Unwin, M.; Mackin, S.; Hodgart, S.; Adjrad, M.

    2004-12-01

    Most people are generally aware of the fact that the GPS receivers used on boats and airplanes use signals transmitted by a constellation of satellites to determine their locations. What is less obvious is that the same signals are constantly being scattered off the surrounding seas and land, and these signals contain valuable and varied information on the Earth's environment. The GNSS bi-static radar experiment carried on the UK disaster monitoring constellation satellite has been collecting and down linking raw data containing ocean reflected GPS signals since its successful commissioning in March of 2004. It is our aim to connect the delay and Doppler shapes of the received ocean scattered waveforms to an observable ocean phenomenon. This has been shown to be possible based on numerous ground and aircraft experiments utilising the same concept. In these cases it was important to obtain a truth measurement to coincide with the experiment data, such as collecting data while flying underneath TOPEX/POSIEDEN as it passes overhead. In the case of collecting data on an orbiting satellite it becomes more complicated. Sea wind estimates have been obtained from the QuickSCAT and JASON satellites as well as from buoy's and weather models. To what extent these independent measurements provide a degree of "truth" depends on several factors. The most obvious of these are the spatial and temporal coincidence with the signal detections. These and other issues will be discussed and the steps that have been taken to improve the validation procedure will be presented. Despite the obstacles encountered, it can be shown that ocean reflected signals from the GPS navigation satellite constellation can be tracked from a low-earth orbiting satellite and that these signals show rough correlation with independent measurements of the sea winds. This breakthrough has the potential to influence a wide range of applications including the determination of sea surface roughness, ocean wind

  1. Analysis of Static Spacecraft Floating Potential at Low Earth Orbit (LEO)

    NASA Technical Reports Server (NTRS)

    Herr, Joel L.; Hwang, K. S.; Wu, S. T.

    1995-01-01

    Spacecraft floating potential is the charge on the external surfaces of orbiting spacecraft relative to the space. Charging is caused by unequal negative and positive currents to spacecraft surfaces. The charging process continues until the accelerated particles can be collected rapidly enough to balance the currents at which point the spacecraft has reached its equilibrium or floating potential. In low inclination. Low Earth Orbit (LEO), the collection of positive ion and negative electrons. in a particular direction. are typically not equal. The level of charging required for equilibrium to be established is influenced by the characteristics of the ambient plasma environment. by the spacecraft motion, and by the geometry of the spacecraft. Using the kinetic theory, a statistical approach for studying the interaction is developed. The approach used to study the spacecraft floating potential depends on which phenomena are being applied. and on the properties of the plasma. especially the density and temperature. The results from kinetic theory derivation are applied to determine the charging level and the electric potential distribution at an infinite flat plate perpendicular to a streaming plasma using finite-difference scheme.

  2. International Space Station as a Platform for Exploration Beyond Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Raftery, Michael; Woodcock, Gordon

    2010-01-01

    The International Space Station (ISS) has established a new model for the achievement of the most difficult engineering goals in space: international collaboration at the program level with competition at the level of technology. This strategic shift in management approach provides long term program stability while still allowing for the flexible evolution of technology needs and capabilities. Both commercial and government sponsored technology developments are well supported in this management model. ISS also provides a physical platform for development and demonstration of the systems needed for missions beyond low earth orbit. These new systems at the leading edge of technology require operational exercise in the unforgiving environment of space before they can be trusted for long duration missions. Systems and resources needed for expeditions can be aggregated and thoroughly tested at ISS before departure thus providing wide operational flexibility and the best assurance of mission success. We will describe representative mission profiles showing how ISS can support exploration missions to the Moon, Mars, asteroids and other potential destinations. Example missions would include humans to lunar surface and return, and humans to Mars orbit as well as Mars surface and return. ISS benefits include: international access from all major launch sites; an assembly location with crew and tools that could help prepare departing expeditions that involve more than one launch; a parking place for reusable vehicles; and the potential to add a propellant depot.

  3. Study on Orbital Decay of Near Earth Satellites with KS Orthogonal Elements

    NASA Astrophysics Data System (ADS)

    Ps, Sandeep

    STUDY ON ORBITAL DECAY OF NEAR EARTH SATELLITES WITH KS ORTHOGONAL ELEMENTS SANDEEP P S The knowledge of satellite orbit decay and its expected life prior to launch is necessary for mission planning purpose. Several sets of data for various parametric studies is sought quite often, it is necessary to minimize computational time involved for generating decay predictions, keeping the prediction accuracy normally good. A number of factors play dominant role in perturbation modelling for near earth satellites such as oblateness of the Earth, presence of the atmosphere, luni-solar attraction and solar radiation pressure. This paper concerns with the study of orbital decay of near earth satellites with KS orthogonal elements, which provide accurate orbit predictions at low computational time. Perturbations considered are due to oblateness of the Earth and the atmospheric drag. The Earth’s zonal harmonic terms J2 to J6 are included and the drag is modeled with an analytical diurnally oblate atmosphere. Effect of Earth’s geomagnetic and solar activity is included in density and density scale height computations. JACCHIA77 atmospheric model is utilized. The developed software is validated with the orbital data of decayed objects taken from www.space-track.org.

  4. The Near-Earth Space Radiation for Electronics Environment

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; LaBel, K. A.

    2004-01-01

    The earth's space radiation environment is described in terms of: a) charged particles as relevant to effects on spacecraft electronics, b) the nature and distribution of trapped and transiting radiation, and c) their effect on electronic components.

  5. Viscoelastic characterization of thin-film polymers exposed to low Earth orbit

    NASA Technical Reports Server (NTRS)

    Letton, Alan; Farrow, Allan; Strganac, Thomas

    1993-01-01

    The materials made available through the Long Duration Exposure Facility (LDEF) satellite provide a set of specimens that can be well characterized and have a known exposure history with reference to atomic oxygen and ultraviolet radiation exposure. Mechanical characteristics measured from control samples and exposed samples provide a data base for predicting the behavior of polymers in low earth orbit. Samples of 1.0 mil thick low density polyethylene were exposed to the low earth orbit environment for a period of six years. These materials were not directly exposed to ram atomic oxygen and offer a unique opportunity for measuring the effect of atomic oxygen and UV radiation on mechanical properties with little concern to the effect of erosion. The viscoelastic characteristics of these materials were measured and compared to the viscoelastic characteristics of control samples. To aid in differentiating the effects of changes in crystallinity resulting from thermal cycling, from the effects of changes in chemical structure resulting from atomic oxygen/UV attack to the polymer, a second set of control specimens, annealed to increase crystallinity, were measured as well. The resulting characterization of these materials will offer insight into the impact of atomic oxygen/UV on the mechanical properties of polymeric materials. The viscoelastic properties measured for the control, annealed, and exposed specimens were the storage and loss modulus as a function of frequency and temperature. From these datum is calculated the viscoelastic master curve derived using the principle of time/temperature superposition. Using the master curve, the relaxation modulus is calculated using the method of Ninomiya and Ferry. The viscoelastic master curve and the stress relaxation modulus provide a direct measure of the changes in the chemical or morphological structure. In addition, the effect of these changes on long-term and short-term mechanical properties is known directly. It

  6. Consequences of Atomic Oxygen Interaction With Silicone and Silicone Contamination on Surfaces in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon K.; Haytas, Christy A.

    1999-01-01

    The exposure of silicones to atomic oxygen in low Earth orbit causes oxidation of the surface, resulting in conversion of silicone to silica. This chemical conversion increases the elastic modulus of the surface and initiates the development of a tensile strain. Ultimately, with sufficient exposure, tensile strain leads to cracking of the surface enabling the underlying unexposed silicone to be converted to silica resulting in additional depth and extent of cracking. The use of silicone coatings for the protection of materials from atomic oxygen attack is limited because of the eventual exposure of underlying unprotected polymeric material due to deep tensile stress cracking of the oxidized silicone. The use of moderate to high volatility silicones in low Earth orbit has resulted in a silicone contamination arrival at surfaces which are simultaneously being bombarded with atomic oxygen, thus leading to conversion of the silicone contaminant to silica. As a result of these processes, a gradual accumulation of contamination occurs leading to deposits which at times have been up to several microns thick (as in the case of a Mir solar array after 10 years in space). The contamination species typically consist of silicon, oxygen and carbon. which in the synergistic environment of atomic oxygen and UV radiation leads to increased solar absorptance and reduced solar transmittance. A comparison of the results of atomic oxygen interaction with silicones and silicone contamination will be presented based on the LDEF, EOIM-111, Offeq-3 spacecraft and Mir solar array in-space results. The design of a contamination pin-hole camera space experiment which uses atomic oxygen to produce an image of the sources of silicone contamination will also be presented.

  7. Dynamical sequestration of the Moon-forming impactor in co-orbital resonance with Earth

    NASA Astrophysics Data System (ADS)

    Kortenkamp, Stephen J.; Hartmann, William K.

    2016-09-01

    Recent concerns about the giant impact hypothesis for the origin of the Moon, and an associated "isotope crisis" may be assuaged if the impactor was a local object that formed near Earth. We investigated a scenario that may meet this criterion, with protoplanets assumed to originate in 1:1 co-orbital resonance with Earth. Using N-body numerical simulations we explored the dynamical consequences of placing Mars-mass companions in various co-orbital configurations with a proto-Earth of 0.9 Earth-masses (M⊕). We modeled 162 different configurations, some with just the four terrestrial planets and others that included the four giant planets. In both the 4- and 8-planet models we found that a single Mars-mass companion typically remained a stable co-orbital of Earth for the entire 250 million year (Myr) duration of our simulations (59 of 68 unique simulations). In an effort to destabilize such a system we carried out an additional 94 simulations that included a second Mars-mass co-orbital companion. Even with two Mars-mass companions sharing Earth's orbit about two-thirds of these models (66) also remained stable for the entire 250 Myr duration of the simulations. Of the 28 2-companion models that eventually became unstable 24 impacts were observed between Earth and an escaping co-orbital companion. The average delay we observed for an impact of a Mars-mass companion with Earth was 102 Myr, and the longest delay was 221 Myr. In 40% of the 8-planet models that became unstable (10 out of 25) Earth collided with the nearly equal mass Venus to form a super-Earth (loosely defined here as mass ≥1.7 M⊕). These impacts were typically the final giant impact in the system and often occurred after Earth and/or Venus has accreted one or more of the other large objects. Several of the stable configurations involved unusual 3-planet hierarchical co-orbital systems.

  8. Earth Observing System (EOS) real-time onboard orbit determination

    NASA Technical Reports Server (NTRS)

    Folta, David C.; Muller, Ron

    1993-01-01

    The paper describes the TDRSS Onboard Navigation System (TONS) selected by NASA/GSFC for the EOS-AM1 spacecraft as the baseline navigation system for real-time onboard orbit determination. Particular attention is given to the TONS algorithms and environmental models, the general design considerations, the algorithm implementation, and the required hardware. Results are presented of the covariance analysis for the nominal onboard and instrument requirements.

  9. Medium Earth Orbits: Is There a Need for a Third Protected Region?

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2010-01-01

    The Inter-Agency Space Debris Coordination Committee (IADC) and the United Nations have adopted the concept of near-Earth regions which should be afforded protection from the accumulation of orbital debris. These regions are low Earth orbit (LEO), which extends up to 2000 km altitude, and geosynchronous orbit (GEO), which includes the volume of space encompassed by 35,786 km +/- 200 km in altitude and +/- 15 degrees in inclination. The region between LEO and GEO is commonly referred to as Medium Earth Orbit (MEO). Although historically a small minority of spacecraft have operated in MEO, the number of such satellites residing in or routinely transiting the zone is increasing. The question thus arises: should MEO be considered an orbital debris protected region? This paper first reviews the characteristics of space systems now utilizing MEO, as well as those anticipated to join them in the near future. MEO is then contrasted with LEO and GEO, both physically and pragmatically. Recommended orbital debris mitigation guidelines for MEO space vehicles are highlighted, and the challenges of spacecraft and launch vehicle stage disposal are recognized. Note is also made of the principal tenets of the United Nations Outer Space Treaty and of recent trends toward de facto partitioning of MEO. Finally, the efficacy and practicality of establishing MEO as a new protected region with regard to orbital debris is addressed.

  10. The Expose-R2 mission: astrobiology and astrochemistry in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Demets, René

    EXPOSE is an exposure platform developed by ESA which permits scientists to install test samples for 1 to 2 years at the outer surface of the ISS. In that way, the impact of the open space environment on biological and biochemical sample materials can be explored. This environment, featuring full-spectrum solar light, near-vacuum, cosmic radiation, wide temperature variations and near-weightlessness, is impossible to reproduce in its entirety in the lab. As such, EXPOSE offers astrochemists and astrobiologists a chance to acquire novel scientific data. Astrochemists are interested in Low Earth Orbit conditions due to the fact that photochemistry in space is quite different from photochemistry on Earth, where the high-energy UV compounds of the solar spectrum are filtered away by our atmosphere. As for the astro biologists, EXPOSE offers an attractive opportunity to expand earlier results obtained during short-duration LEO flights, which have shown that particular microbes and, amazingly, even some multi-cellular macroscopic organisms were able to cope with a two-week exposure to space. The open space environment, often described as harsh and hostile, can apparently be tolerated by some robust inhabitants of our Earth - unprotected, in the absence of a space suit! The first mission of EXPOSE, as an external payload on the European Columbus module, happened during 2008-2009 with the test samples provided by five separate research teams. Three additional teams were involved in the monitoring of space environment. The results were published collectively in 2012 in a special issue of the monthly journal Astrobiology. Several organisms survived, having spent 1.5 years in space. The second mission was called EXPOSE-R, the R referring to ‘Russian segment’, the location where the EXPOSE instrument was installed this time. The EXPOSE-R mission took place in 2009-2011, ten science teams were involved. The publication of the results, again as a collection, is currently in

  11. MEMO: Mars Environment and Magnetic Orbiter: a Cosmic Vision proposal

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Langlais, B.; Fouchet, T.; Chassefière, E.; Sotin, C.; Barabash, S.; Dehant, V.; Lammer, H.; Mandea, M.; Vennerstrom, S.; Coates, A.; D, Breuer; Paetzold, M.; Forget, F.; Tarits, P.; Menvielle, M.; Read, P.; Lopez-Valverde, M.; S., Lewis; Pais, A.

    2007-08-01

    Recent observations by the ESA spacecraft Mars Express, the two NASA Rovers Opportunity and Spirit, as well as by the NASA probe Mars Global Surveyor, have changed our view on the evolution of Mars. The most dramatic results are the limited amount of visible minerals related to the action of water at its surface, the very intense lithospheric magnetic fields, and the current weak ion escape driven by the solar wind. These observations suggest that the period of a "wet Mars" was short and that Mars lost its water before 3.5 Gyr ago, when the magnetic field of Mars died out. Among the different questions that are raised by existing results, the role of the superficial magnetic field shielding Mars' surface and lower atmosphere from the high-energy ions and the dependency of the escape rate on solar conditions are first order questions that cannot be addressed without new measurements by a dedicated mission. However, these questions cannot be fully solved without understanding how carbon dioxide, water and chemical species are cycled through atmosphere, clouds, polar caps and other reservoirs. An integrated view of Martian matter and energy cycles, from the surface up to solar wind interaction regions and beyond, is the next step toward deciphering past climate. The Mars Environment and Magnetic Orbiter mission (MEMO) is devoted: (1) to measure temperature, wind and chemical composition in order to characterize processes coupling low, middle and high atmospheric layers, (2) to describe atmospheric oxidation processes and to search for organic chemical compounds, (3) to measure water isotopic fractionation in the low atmosphere in order to characterize water sources, sinks and transport, with a focus on polar processes, (4) to investigate the dependency of atmospheric and neutral and ion escape dynamics on short and long timescales versus solar wind and radiation variabilities, (5) to map the crustal magnetic field with an unprecedented spatial resolution that would

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

    NASA Technical Reports Server (NTRS)

    Ruttley, Tara M.; Robinson, Julie A.

    2010-01-01

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

  13. Space environmental effects on LDEF low Earth orbit exposed graphite reinforced polymer matrix composites

    NASA Technical Reports Server (NTRS)

    George, Pete

    1992-01-01

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

  14. The Orbital Architecture of 55 Cnc: An Orbital Resonance, Jupiter Analog, and Transiting Super-Earth

    NASA Astrophysics Data System (ADS)

    Nelson, Benjamin E.; Payne, M.; Ford, E.; Wright, J.

    2011-09-01

    55 Cnc is the only naked eye star with a known transiting planet (Winn et al. 2011) and one of a few systems with five known planets characterized via Doppler methods. The planets span a wide range of masses and orbital periods. We investigate the orbital architecture, focusing on two of the giant planets near 3:1 mean-motion resonance and the potential impact on the dynamical effects on the other planets. To quantify the uncertainty in the orbital parameters of the 55 Cnc system requires exploring a high-dimensional ( 35) parameter space and using self-consistent N-body integrations, both of which are computationally demanding. To surmount these challenges, we apply a differential evolution Markov chain Monte Carlo algorithm to characterize the orbital properties and masses. We present these results and discuss the implications on the dynamical evolution of the 55 Cnc system.

  15. High-precision orbit determination for high-earth elliptical orbiters using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Lichten, S. M.; Estefan, J. A.

    1990-01-01

    Orbit covariance analyses pertaining to the Japanese VLBI Space Observatory Program (VSOP) MUSES-B satellite and to the International VLBI Satellite are presented. It is determined that a combination of Doppler and GPS measurements can provide the orbit accuracy required to support advanced radio interferometric experiments. For the VSOP, the required orbit accuracy of 130 m is easily met with two-way Doppler as the primary type of data; the 0.4 cm/s VSOP velocity requirement is also feasible provided that precise ground calibrations of tropospheric delays and station coordinates are available. It is concluded that combining the data from a VSOP GPS flight instrument with the ground GPS and two-way Doppler data will significantly enhance orbit determination accuracy in position and velocity.

  16. Eclipse intervals for satellites in circular orbit under the effects of Earth's oblateness and solar radiation pressure

    NASA Astrophysics Data System (ADS)

    Ismail, M. N.; Bakry, A.; Selim, H. H.; Shehata, M. H.

    2015-06-01

    In this work, the circumstances of eclipse for a circular satellites' orbit are studied. The time of passage of the ingress and egress points is calculated. Finally, the eclipse intervals of satellites' orbit are calculated. An application was done taken into account the effects of solar radiation pressure and Earth's oblateness on the orbital elements of circular orbit satellite.

  17. ISS Update: From Orbiting Earth to Living Underwater

    NASA Video Gallery

    NASA Public Affairs Officer Brandi Dean interviews astronaut and NEEMO (NASA Extreme Environment Mission Operations) 16 Commander Dottie Metcalf-Lindenburger. Three NASA astronauts, a NASA research...

  18. Redox State of the Neoarchean Earth Environment

    NASA Technical Reports Server (NTRS)

    Zerkle, Aubrey L.; Claire, Mark W.; Domagal-Goldman, Shawn; Farquhar, James; Poulton, Simon W.

    2011-01-01

    A Titan-like organic haze has been hypothesized for Earth's atmosphere prior to widespread surface oxygenation approx.2.45 billion years ago (Ga). We present a high-resolution record of quadruple sulfur isotopes, carbon isotopes, and Fe speciation from the approx.2.65-2.5 Ga Ghaap Group, South Africa, which suggest a linkage between organic haze and the biogeochemical cycling of carbon, sulfur, oxygen, and iron on the Archean Earth. These sediments provide evidence for oxygen production in microbial mats and localized oxygenation of surface waters. However, this oxygen production occurred under a reduced atmosphere which existed in multiple distinct redox states that correlate to changes in carbon and sulfur isotopes. The data are corroborated by photochemical model results that suggest bi-stable transitions between organic haze and haze-free atmospheric conditions in the Archean. These geochemical correlations also extend to other datasets, indicating that variations in the character of anomalous sulfur fractionation could provide insight into the role of carbon-bearing species in the reducing Archean atmosphere.

  19. Electromagnetic wave probing of Earth's environment

    NASA Technical Reports Server (NTRS)

    Kong, Jin AU

    1988-01-01

    Polarimetric radar backscattering from anisotropic Earth terrain such as snow-covered ice fields and vegetation fields with row structures provides a challenging modeling problem from the electromagnetic wave point of view. Earth terrain covers are modeled as random media characterized by different dielectric constants and correlation functions. A three-layer model will be used to simulate a vegetation field or a snow-covered ice field with the top layer being snow or leaves, the middle layer being ice of trunks, and the bottom layer being sea water or ground. The volume scattering effects of snow-covered sea ice are studied with a three-layer random medium model for microwave remote sensing. The strong fluctuation theory and the bilocal approximation are applied to calculate the effective permittivities for snow and sea ice. The wave scattering theory in conjunction with the distorted Born approximation is then used to compute bistatic coefficients and backscattering cross sections. Theoretical results are illustrated by matching experimental data for dry snow-covered thick first-year sea ice at Point Barrow. The results derived can also be applied to the passive remote sensing by calculating the emissivity from the bistatic scattering coefficients.

  20. Thermal and orbital analysis of Earth monitoring Sun-synchronous space experiments

    NASA Technical Reports Server (NTRS)

    Killough, Brian D.

    1990-01-01

    The fundamentals of an Earth monitoring Sun-synchronous orbit are presented. A Sun-synchronous Orbit Analysis Program (SOAP) was developed to calculate orbital parameters for an entire year. The output from this program provides the required input data for the TRASYS thermal radiation computer code, which in turn computes the infrared, solar and Earth albedo heat fluxes incident on a space experiment. Direct incident heat fluxes can be used as input to a generalized thermal analyzer program to size radiators and predict instrument operating temperatures. The SOAP computer code and its application to the thermal analysis methodology presented, should prove useful to the thermal engineer during the design phases of Earth monitoring Sun-synchronous space experiments.

  1. Servicing and Deployment of National Resources in Sun-Earth Libration Point Orbits

    NASA Technical Reports Server (NTRS)

    Folta, David C.; Beckman, Mark; Mar, Greg C.; Mesarch, Michael; Cooley, Steven; Leete, Steven J.

    2002-01-01

    Spacecraft travel between the Sun-Earth system, the Earth-Moon system, and beyond has received extensive attention recently. The existence of a connection between unstable regions enables mission designers to envision scenarios of multiple spacecraft traveling cheaply from system to system, rendezvousing, servicing, and refueling along the way. This paper presents examples of transfers between the Sun-Earth and Earth-Moon systems using a true ephemeris and perturbation model. It shows the (Delta)V costs associated with these transfers, including the costs to reach the staging region from the Earth. It explores both impulsive and low thrust transfer trajectories. Additionally, analysis that looks specifically at the use of nuclear power in libration point orbits and the issues associated with them such as inadvertent Earth return is addressed. Statistical analysis of Earth returns and the design of biased orbits to prevent any possible return are discussed. Lastly, the idea of rendezvous between spacecraft in libration point orbits using impulsive maneuvers is addressed.

  2. Studies of neutron and proton nuclear activation in low-Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1982-01-01

    The expected induced radioactivity of experimental material in low Earth orbit was studied for characteristics of activating particles such as cosmic rays, high energy Earth albedo neutrons, trapped protons, and secondary protons and neutrons. The activation cross sections for the production of long lived radioisotopes and other existing nuclear data appropriate to the study of these reactions were compiled. Computer codes which are required to calculate the expected activation of orbited materials were developed. The decreased computer code used to predict the activation of trapped protons of materials placed in the expected orbits of LDEF and Spacelab II. Techniques for unfolding the fluxes of activating particles from the measured activation of orbited materials are examined.

  3. Solar dynamic heat receiver thermal characteristics in low earth orbit

    NASA Technical Reports Server (NTRS)

    Wu, Y. C.; Roschke, E. J.; Birur, G. C.

    1988-01-01

    A simplified system model is under development for evaluating the thermal characteristics and thermal performance of a solar dynamic spacecraft energy system's heat receiver. Results based on baseline orbit, power system configuration, and operational conditions, are generated for three basic receiver concepts and three concentrator surface slope errors. Receiver thermal characteristics and thermal behavior in LEO conditions are presented. The configuration in which heat is directly transferred to the working fluid is noted to generate the best system and thermal characteristics. as well as the lowest performance degradation with increasing slope error.

  4. Is Mars a habitable environment for extremophilic microorganisms from Earth?

    NASA Astrophysics Data System (ADS)

    Rettberg, Petra; Reitz, Guenther; Flemming, Hans-Curt; Bauermeister, Anja

    In the last decades several sucessful space missions to our neighboring planet Mars have deepened our knowledge about its environmental conditions substantially. Orbiters with intruments for remote sensing and landers with sophisticated intruments for in situ investigations resulted in a better understanding of Mars’ radiation climate, atmospheric composition, geology, and mineralogy. Extensive regions of the surface of Mars are covered with sulfate- and ferric oxide-rich layered deposits. These sediments indicate the possible existence of aqueous, acidic environments on early Mars. Similar environments on Earth harbour a specialised community of microorganisms which are adapted to the local stress factors, e.g. low pH, high concentrations of heavy metal ions, oligotrophic conditions. Acidophilic iron-sulfur bacteria isolated from such habitats on Earth could be considered as model organisms for an important part of a potential extinct Martian ecosystem or an ecosystem which might even exist today in protected subsurface niches. Acidithiobacillus ferrooxidans was chosen as a model organism to study the ability of these bacteria to survive or grow under conditions resembling those on Mars. Stress conditions tested included desiccation, radiation, low temperatures, and high salinity. It was found that resistance to desiccation strongly depends on the mode of drying. Biofilms grown on membrane filters can tolerate longer periods of desiccation than planktonic cells dried without any added protectants, and drying under anaerobic conditions is more favourable to survival than drying in the presence of oxygen. Organic compounds such as trehalose and glycine betaine had a positive influence on survival after drying and freezing. A. ferrooxidans was shown to be sensitive to high salt concentrations, ionizing radiation, and UV radiation. However, the bacteria were able to utilize the iron minerals in Mars regolith mixtures as sole energy source. The survival and growth of

  5. KOI2138 -- a Spin-Orbit Aligned Intermediate Period Super-Earth

    NASA Astrophysics Data System (ADS)

    Barnes, Jason W.

    2015-11-01

    A planet's formation and evolution are encoded in spin-orbit alignment -- the planet's inclination relative to its star's equatorial plane. While the solar system's spin-orbit aligned planets indicate our own relatively quiescent history, many close-in giant planets show significant misalignment. Some planets even orbit retrograde! Hot Jupiters, then, have experienced fundamentally different histories than we experienced here in the solar system. In this presentation, I will show a new determination of the spin-orbit alignment of 2.1 REarth exoplanet candidate KOI2138. KOI2138 shows a gravity-darkened transit lightcurve that is consistent with spin-orbit alignment. This measurement is important because the only other super-Earth with an alignment determination (55 Cnc e, orbit period 0.74 days) is misaligned. With an orbital period of 23.55 days, KOI2138 is far enough from its star to avoid tidal orbit evolution. Therefore its orbit is likely primordial, and hence it may represent the tip of an iceberg of terrestrial, spin-orbit aligned planets that have histories that more closely resemble that of the solar system's terrestrial planets.

  6. Study of multi-kW solar arrays for Earth orbit applications: Midterm performance review

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Planar and concentrator solar array concepts capable of providing 300 kW to 1000 kW in low Earth orbit applications in the 1987 time period at an array recurring cost less than or equal to thirty dollars per watt are examined. Silicon and gallium arsenide solar cell applicability are evaluated. On-orbit maintenance by space shuttle is also investigated. Design configurations for the solar arrays and solar cells are recommended.

  7. Space shuttle: Program overview. [low-cost transportation to and from earth orbits

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The primary design and operations goal for the space shuttle program to provide low-cost transportation to and from earth orbits for the purpose of conducting investigations in space via spacelabs and free flying or automated satellites is reviewed. The space shuttle system and mission profile is described along with the space shuttle orbiter system and payloads accommodations, attachments, and handling. The implications the space shuttle program has for international cooperation in space are mentioned.

  8. Computer subroutines for estimation of human exposure to radiation in low Earth orbit

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  9. Earth-to-orbit reusable launch vehicles: A comparative assessment

    NASA Technical Reports Server (NTRS)

    Chase, R. L.

    1978-01-01

    A representative set of space systems, functions, and missions for NASA and DoD from which launch vehicle requirements and characteristics was established as well as a set of air-breathing launch vehicles based on graduated technology capabilities corresponding to increasingly higher staging Mach numbers. The utility of the air-breathing launch vehicle candidates based on lift-off weight, performance, technology needs, and risk was assessed and costs were compared to alternative concepts. The results indicate that a fully reusable launch vehicle, whether two stage or one stage, could potentially reduce the cost per flight 60-80% compared to that for a partially reusable vehicle but would require advances in thermal protection system technology. A two-stage-to-orbit, parallel-lift vehicle with an air-breathing booster would cost approximately the same as a single-stage-to-orbit vehicle, but the former would have greater flexibility and a significantly reduced developmental risk. A twin-booster, subsonic-staged, parallel-lift vehicle represents the lowest system cost and developmental risk. However, if a large supersonic turbojet engine in the 350,000-N thrust class were available, supersonic staging would be preferred, and the investment in development would be returned in reduced program cost.

  10. Studies in geophysics: The Earth's electrical environment

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The Earth is electrified. Between the surface and the outer reaches of the atmosphere, there is a global circuit that is maintained by worldwide thunderstorm activity and by upper atmospheric dynamo processes. The highest voltages approach a billion volts and are generated within thunderclouds, where lightning is a visual display of the cloud's electrical nature. The largest currents in the circuit, approaching a million amperes, are associated with the aurora. Because there have been significant advances in understanding many of the component parts of the global electric circuit (lightning, cloud electrification, electrical processes in specific atmospheric regions, and telluric currents), a principal research challenge is to understand how these components interact to shape the global circuit. Increased basic understanding in this field has many potential practical applications, including lightning protection, the design of advanced aircraft and spacecraft, and improvements in weather prediction.

  11. Lissajous Orbit Control for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission

    NASA Technical Reports Server (NTRS)

    Roberts, Craig; Case, Sarah; Reagoso, John

    2015-01-01

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

  12. Earth orbital assessment of solar electric and solar sail propulsion systems

    NASA Technical Reports Server (NTRS)

    Teeter, R. R.

    1977-01-01

    The earth orbital applications potential of Solar Electric (Ion Drive) and Solar Sail low-thrust propulsion systems are evaluated. Emphasis is placed on mission application in the 1980s. The two low-thrust systems are compared with each other and with two chemical propulsion Shuttle upper stages (the IUS and SSUS) expected to be available in the 1980s. The results indicate limited Earth orbital application potential for the low-thrust systems in the 1980s (primarily due to cost disadvantages). The longer term potential is viewed as more promising. Of the two systems, the Ion Drive exhibits better performance and appears to have better overall application potential.

  13. Instrumentation for near-Earth measurement of orbital debris and cosmic dust particles

    NASA Technical Reports Server (NTRS)

    Tuzzolino, Anthony J.

    1992-01-01

    Dust instrumentation based on polyvinylidene fluoride (PVDF) dust sensor arrays is described which will measure the masses, fluxes, velocities, and trajectories of orbital debris particles and natural micrometeoroids. Orbital debris particles are distinguished from natural particles (cosmic dust) by means of the velocity/trajectory information. The instrumentation will measure particle trajectory with a mean error of approximately 7 degrees (for isotropic flux) and is designed for measurements over the particle diameter range of approximately 2 to 200 micro-m. For future missions having Earth-return capabilities, arrays of capture cell devices positioned behind the PVDF trajectory system would provide for Earth-based chemical and isotopic analysis of captured dust.

  14. Study of multi-kW solar arrays for Earth orbit application

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Low cost low Earth orbit (LOW) and geosynchronous Earth orbit (GEO) Solar Array concepts in the 300 to 1000 kW range which could be reduced to hardware in the mid 1980's, are identified. Size scaling factors and longer life demands are recognized as the prime drivers for the designs if low life cycle costs for energy are to be achieved. Technology is identified which requires further development in order to assure component readiness and availability. Use of the low concentration ratio (CR) concentrator, which uses gallium arsenide solar cells for both LEO and GEO applications, is recommended.

  15. Earth Trek...Explore Your Environment.

    ERIC Educational Resources Information Center

    Schneider, Gerald

    This publication introduces children to water, air, and noise pollution, solid waste disposal, and pesticide use problems. Several pollution problems are explained and the importance of solving them is stressed. Some concepts such as recycling, closed systems, and environments that are related to pollution problems are also introduced. Each…

  16. Space Weather and Particle Effects on the Orbital Environment of PROBA2

    NASA Astrophysics Data System (ADS)

    West, Matthew; Seaton, Dan; Dominique, Marie; Berghmans, David; Nicula, Bogdan; Pylyser, Erik; Stegen, Koen; De Keyser, Johan

    2013-04-01

    Data from the EUV imager SWAP and UV/EUV radiometer LYRA on board the PROBA2 spacecraft are regularly affected by space weather conditions along the spacecraft's orbital path. While these effects are generally removed from calibrated data intended for scientific analysis, they provide an interesting opportunity to characterize the evolution near-Earth space environment as the result of changing space weather conditions. Here we present an analysis of these space weather effects on PROBA2 observations and some conclusions about both the long-term evolution of the inner magnetosphere and short-term events driven by the active sun.

  17. The Martian Radiation Environment from Orbit and on the Surface

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.; Howe, S. D.

    1999-01-01

    A good knowledge of the Martian radiation environment and its interactions with Mars is needed for many reasons. It is needed to help unfold the results of the Mars-2001 orbiter's gamma-ray spectrometer (GRS) and neutron spectrometers (NS) to determine elemental abundances on the Martian surface. It is needed to interpret the measurements of the Martian Radiation Environment Experiments (MARIE) on both the Mars 2001 orbiter and lander. It is needed to calculate production rates of cosmogenic nuclides that will be measured in samples returned from Mars. It is needed to determine the doses that astronauts would receive in Martian orbit and especially on the surface of Mars. We discuss the two types of energetic particles in the vicinity of Mars and the nature of their interactions. Solar energetic particles (SEPs) occur very rarely but can have high fluxes that are dangerous in space. However, their energies are low enough that few solar energetic particles reach the surface of Mars. Their interactions can be fairly easily modeled because SEPs create few secondary particles. Galactic cosmic rays (GCRs) have high energies and are the dominant source of energetic particles on the Martian surface, mainly secondary neutrons. Modeling their interactions is complicated because of the range of nuclei in the GCR and their high energies. Work at Los Alamos on GCR interactions will be presented.

  18. Development of a Spacecraft concept to remove space debris from low earth orbit

    NASA Astrophysics Data System (ADS)

    David, Emmanuelle; Starke, Jürgen; Wiedemann, Carsten

    On 2009 February 10, Iridium 33 and Cosmos 2251 collided in Low Earth orbit (LEO). Lately, crashes in space occur more often. The resulting debris represents a future risk for the pop-ulation in space. That is why some international guidelines have been set in order to reduce the number of orbiting objects, or at least decrease the growth. Hence new spacecrafts and launcher upper stages should be designed to limit their presence or be actively removed in protected LEO regions to less than 25 years after their end of mission. One debris mitigation measure is the removal of object after their end of mission. Within the low Earth orbit, the highest population density of potential hazardous inoperable spacecrafts and launcher stages are located in the so called sun synchronous orbit (SSO). This orbit combines altitude (around 900 km) and inclination (around 98) in such way that an object on orbit ascends or descends over any given point of the earth surface at the same mean solar time. Thus this orbit is commonly used for weather and earth observation satellites as ENVISAT. Since the satellites and space debris orbits cross each others at the pole, there is a high collision probability in the SSO vicinity. Furthermore the relative velocity is extremely high (around 15 km/s) as the objects can meet face to face. Those collisions are dramatic. The study focuses on the architecture assessment of a SSO satellite removal mission. The analysis takes into account the complete life cycle of the satellite remover including the launch, the rendezvous with the target(s), the capture and de-orbit as well as de-orbit of the remover satellite. . . The different concepts are considering either a pulling/pushing of the satellite by a remover spacecraft, either the delivering and implementation of an additional kit. Various technologies are currently developed to answer to this new demand (momentum exchange or electro dynamical tethers, solar sails, etc). It is also considering the

  19. In-Orbit Earth Radiation Budget Satellite (ERBS) Battery Switch

    NASA Technical Reports Server (NTRS)

    Ahmad, Anisa; Enciso, Marlon; Rao, Gopalakrishna

    1999-01-01

    This presentation reviews the history of the Earth Radiation Budget Satellite (ERBS) and the problems which were experienced with the batteries. After two cells shorted on the first Battery, the decision was made to take battery 1 of line in late 1992. This left the second battery supporting all loads. The second battery began to experience problems in 1998 into 1999. The decision was made to bring the first battery on line and take the second battery off line. The steps to switching the batteries are reviewed, and the results are discussed.

  20. ADCS controllers comparison for small satellitess in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  1. Environmental Durability Issues for Solar Power Systems in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  2. Environmental durability issues for solar power systems in low earth orbit

    SciTech Connect

    Groh, K.K. de; Banks, B.A.; Smith, D.C.

    1995-10-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  5. The Impact of New Trends in Satellite Launches on Orbital Debris Environment

    NASA Technical Reports Server (NTRS)

    Karacalioglu, Arif Goktug; Stupl, Jan

    2016-01-01

    The main goal of this study is to examine the impact of new trends in satellite launch activities on the orbital debris environment and collision risk. Starting from the launch of the first artificial satellite in 1957, space borne technology has become an indispensable part of our lives. More than 6,000 satellites have been launched into Earth orbit. Though the annual number of satellites launched stayed flat for many decades, the trend has recently changed. The satellite market has been undergoing a major evolution with new space companies replacing the traditional approach of deploying a few large, complex and costly satellites with an approach to use a multitude of smaller, less complex and cheaper satellites. This new approach creates a sharp increase in the number of satellites and so the historic trends are no longer representative. As a foundation for this study, a scenario for satellite deployments based on the publicly announced future satellite missions has been developed. These constellation-deploying companies include, but are not limited to, Blacksky, CICERO, EROS, Landmapper, Leosat, Northstar, O3b, OmniEarth, OneWeb, Orbcomm, OuterNet, PlanetIQ, Planet Labs, Radarsat, RapidEye Next Generation, Sentinel, Skybox, SpaceX, and Spire. Information such as the annual number of launches, the number of orbital planes to be used by the constellation, as well as apogee, perigee, inclination, spacecraft mass and area were included or approximated. Besides the production of satellites, a widespread ongoing effort to enhance orbital injection capabilities will allow delivery of more spacecraft more accurately into Earth orbits. A long list of companies such as Microcosm, Rocket Lab, Firefly Space Systems, Sierra Nevada Corporation and Arca Space Corporation are developing new launch vehicles dedicated for small satellites. There are other projects which intend to develop interstages with propulsive capabilities which will allow the deployment of satellites into

  6. Simplified model for solar cosmic ray exposure in manned Earth orbital flights

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Khandelwal, Govind S.; Shinn, Judy L.; Nealy, John E.; Townsend, Lawrence W.; Cucinotta, Francis A.

    1990-01-01

    A simple calculational model is derived for use in estimating solar cosmic ray exposure to critical body organs in low-Earth orbit at the center of a large spherical shield of fixed thickness. The effects of the Earth's geomagnetic field, including storm conditions and the astronauts' self-shielding, are evaluated explicitly. The magnetic storm model is keyed to the planetary index K(sub p).

  7. Spin-orbit thermal entanglement in a rare-earth-metal ion: Susceptibility witness

    NASA Astrophysics Data System (ADS)

    Duarte, O. S.; Castro, C. S.; Reis, M. S.

    2013-07-01

    In the present work, we explore the thermal entanglement between spin and orbital angular momentum in a rare-earth ion. A witness, based on the magnetic susceptibility and capable of revealing entanglement between these two angular momenta of different nature, is introduced. We found entanglement temperatures of 322 K for promethium and 715 K for samarium. These high temperatures make interesting the use of rare-earth in applications of quantum-information processes at room temperature.

  8. Earth-to-Geostationary Orbit Transportation for Space Solar Power System Development

    NASA Technical Reports Server (NTRS)

    Martin, James A.; Donahue, Benjamin B.; Lawrence, Schuyler C.; McClanahan, James A.; Carrington, Connie K. (Technical Monitor)

    2000-01-01

    Space solar power satellites have the potential to provide abundant quantities of electricity for use on Earth. One concept, the Sun Tower, can be assembled in geostationary orbit from pieces transferred from Earth. The cost of transportation is one of the major hurdles to space solar power. This study found that autonomous solar-electric transfer is a good choice for the transportation from LEO to GEO.

  9. Spacecraft orbit/earth scan derivations, associated APL program, and application to IMP-6

    NASA Technical Reports Server (NTRS)

    Smith, G. A.

    1971-01-01

    The derivation of a time shared, remote site, demand processed computer program is discussed. The computer program analyzes the effects of selected orbit, attitude, and spacecraft parameters on earth sensor detections of earth. For prelaunch analysis, the program may be used to simulate effects in nominal parameters which are used in preparing attitude data processing programs. After launch, comparison of results from a simulation and from satellite data will produce deviations helpful in isolating problems.

  10. Simplified model for solar cosmic ray exposure in manned Earth orbital flights

    SciTech Connect

    Wilson, J.W.; Khandelwal, G.S.; Shinn, J.L.; Nealy, J.E.; Townsend, L.W.; Cucinotta, F.A.

    1990-05-01

    A simple calculational model is derived for use in estimating solar cosmic ray exposure to critical body organs in low-Earth orbit at the center of a large spherical shield of fixed thickness. The effects of the Earth's geomagnetic field, including storm conditions and the astronauts' self-shielding, are evaluated explicitly. The magnetic storm model is keyed to the planetary index K(sub p).

  11. Technology Development to Support Human Health and Performance in Exploration Beyond Low Earth Orbit

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  12. Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  13. Free space laser communication experiments from Earth to the Lunar Reconnaissance Orbiter in lunar orbit.

    PubMed

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

    2013-01-28

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model. PMID:23389171

  14. Kepler's Orbit

    NASA Video Gallery

    Kepler does not orbit the Earth, rather it orbits the Sun in concert with the Earth, slowly drifting away from Earth. Every 61 Earth years, Kepler and Earth will pass by each other. Throughout the ...

  15. Relative Attitude Determination of Earth Orbiting Formations Using GPS Receivers

    NASA Technical Reports Server (NTRS)

    Lightsey, E. Glenn

    2004-01-01

    Satellite formation missions require the precise determination of both the position and attitude of multiple vehicles to achieve the desired objectives. In order to support the mission requirements for these applications, it is necessary to develop techniques for representing and controlling the attitude of formations of vehicles. A generalized method for representing the attitude of a formation of vehicles has been developed. The representation may be applied to both absolute and relative formation attitude control problems. The technique is able to accommodate formations of arbitrarily large number of vehicles. To demonstrate the formation attitude problem, the method is applied to the attitude determination of a simple leader-follower along-track orbit formation. A multiplicative extended Kalman filter is employed to estimate vehicle attitude. In a simulation study using GPS receivers as the attitude sensors, the relative attitude between vehicles in the formation is determined 3 times more accurately than the absolute attitude.

  16. Differential neutron energy spectra measured on spacecraft low Earth orbit

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Frank, A. L.; Dudkin, E. V.; Potapov, Yu. V.; Akopova, A. B.; Melkumyan, L. V.

    1995-01-01

    Two methods for measuring neutrons in the range from thermal energies to dozens of MeV were used. In the first method, alpha-particles emitted from the (sup 6) Li(n.x)T reaction are detected with the help of plastic nuclear track detectors, yielding results on thermal and resonance neutrons. Also, fission foils are used to detect fast neutrons. In the second method, fast neutrons are recorded by nuclear photographic emulsions (NPE). The results of measurements on board various satellites are presented. The neutron flux density does not appear to correlate clearly with orbital parameters. Up to 50% of neutrons are due to albedo neutrons from the atmosphere while the fluxes inside the satellites are 15-20% higher than those on the outside. Estimates show that the neutron contribution to the total equivalent radiation dose reaches 20-30%.

  17. Experience our Planet - Interpreting Earth Sciences in a Museum Environment

    NASA Astrophysics Data System (ADS)

    Schneider, S.

    2012-12-01

    Earth science interpretation is more than giving your audience facts and figures. It is about relating Earth sciences to something within the personality or experience of your audience. It is about revelation based on information rather than just giving away information per se. And: The chief aim of interpretation is not instruction but provocation. A great environment for Earth science interpretation is a museum. Whether it is an art gallery, a technology exhibition or a national park's visitor center is irrelevant. Earth science interpretation is possible everywhere and sometimes even more successful in unsuspected locations than in natural history museums. Earth sciences have just started to use the potential which lies within museum environments. A historic view on Earth sciences and natural hazard research can be given in art galleries. The technology used in research can be showcased and - sometimes - even tested in science centers and technology museums. National Parks provide the best opportunity to actually experience the dynamic planet Earth live. This talk aims towards giving an insight view on how to conduct interpretive programs in museums, how to utilize the treasures and possibilities provided by museums and national parks and to encourage scientists to go to these places for face-to-face Earth science interpretation.

  18. Targeting Ballistic Lunar Capture Trajectories Using Periodic Orbits in the Sun-Earth CRTBP

    NASA Technical Reports Server (NTRS)

    Cooley, D.S.; Griesemer, Paul Ricord; Ocampo, Cesar

    2009-01-01

    A particular periodic orbit in the Earth-Sun circular restricted three body problem is shown to have the characteristics needed for a ballistic lunar capture transfer. An injection from a circular parking orbit into the periodic orbit serves as an initial guess for a targeting algorithm. By targeting appropriate parameters incrementally in increasingly complicated force models and using precise derivatives calculated from the state transition matrix, a reliable algorithm is produced. Ballistic lunar capture trajectories in restricted four body systems are shown to be able to be produced in a systematic way.

  19. Extrasolar Giant Planet in Earth-like Orbit

    NASA Astrophysics Data System (ADS)

    1999-07-01

    Discovery from a Long-term Project at La Silla A new extrasolar planet has been found at the ESO La Silla Observatory as a companion to iota Horologii (iota Hor) . This 5.4-mag solar-type star is located at a distance of 56 light-years and is just visible to the unaided eye in the southern constellation Horologium (The Pendulum Clock). The discovery is the result of a long-term survey of forty solar-type stars that was begun in November 1992. It is based on highly accurate measurements of stellar radial velocities, i.e. the speed with which a star moves along the line of sight. The presence of a planet in orbit around a star is inferred from observed, regular changes of this velocity, as the host star and its planet revolve around a common center of gravity. Since in all cases the star is much heavier than the planet, the resulting velocity variations of the star are always quite small. The team that found the new planet, now designated iota Hor b , consists of Martin Kürster , Michael Endl and Sebastian Els (ESO-Chile), Artie P. Hatzes and William D. Cochran (University of Texas, Austin, USA), and Stefan Döbereiner and Konrad Dennerl (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany). Iodine cell provides very accurate velocity measurements iota Hor b represents the first discovery of an extrasolar planet with an ESO instrument [1]. The finding is based on data obtained with ESO's highest-resolution spectrograph, the Coudé Echelle Spectrometer (CES) at the 1.4-m Coudé Auxiliary Telescope (CAT). While this telescope has recently been decommissioned, the CES instrument is now coupled via an optical fiber link to the larger ESO 3.6-m telescope, thus permitting the continuation of this survey. The high precision radial velocity measurements that are necessary for a study of this type were achieved by means of a special calibration technique. It incorporates an iodine gas absorption cell and sophisticated data modelling. The cell is used like

  20. Prevalence of Earth-size planets orbiting Sun-like stars

    PubMed Central

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

    2013-01-01

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