Silicon Schottky Diode Safe Operating Area

NASA Technical Reports Server (NTRS)

Casey, Megan C.; Campola, Michael J.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Phan, Anthony M.; LaBel, Kenneth A.

2016-01-01

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

Characterization of Candidate Solar Sail Material Exposed to Space Environmental Effects

NASA Technical Reports Server (NTRS)

Edwards, David; Hovater, Mary; Hubbs, Whitney; Wertz, George; Hollerman, William; Gray, Perry

2003-01-01

Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Solar sails are not limited by reaction mass and provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this method would need to deploy a thin sail that could be as large as many kilometers in extent. The availability of strong, ultra lightweight, and radiation resistant materials will determine the future of solar sailing. The National Aeronautics and Space Administration's Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra lightweight materials for spacecraft propulsion. The Space Environmental Effects Team at MSFC is actively characterizing candidate solar sail material to evaluate the thermo-optical and mechanical properties after exposure to space environmental effects. This paper will describe the exposure of candidate solar sail materials to emulated space environmental effects including energetic electrons, combined electrons and Ultraviolet radiation, and hypervelocity impact of irradiated solar sail material. This paper will describe the testing procedure and the material characterization results of this investigation.

The search for materials to mitigate spacecraft charging

NASA Technical Reports Server (NTRS)

Losure, Nancy S.

1996-01-01

As spacecraft orbit the earth, they encounter a variety of particles and radiation. Charged particles are common enough that a spacecraft can collect substantial charges on its surfaces. If these charges are not bled off, they can accumulate until electrostatic discharges occur between a charged surface and some lower-potential location on the craft. Electrostatic discharge (ESD) is the suspected culprit in a number of spacecraft failures. Silverized Teflon film has become the standard heat-reflecting outer layer of spacecraft because of its flexibility, chemical inertness, and low volatiles content. However, as spacecraft are designed to operate in orbits with greater probability of accumulating enough ions and electrons to create ESD, the Teflon-based thermal control blankets are becoming a liability. Unless stringent (and sometimes burdensome) shielding measures are taken, ESD can upset delicate electronic systems by upsetting or destroying components, interfering with radio signals, garbling internal instructions, and so on. As orbits become higher and more eccentric, as electronics become more sensitive, and as fault-free operation becomes more crucial, it is becoming necessary to find a replacement for silver/Teflon that has comparable strength, flexibility and chemical inertness, as well as a much lower potential for ESD. This is a report of the steps taken toward the goal of selecting a replacement for silver/Teflon during the Summer of 1995. It is a condensation of a much larger report available on request from the author. Three tasks were undertaken. Task 1 was to specify desirable properties for thermal control blankets. The second task was to collect data on materials properties from the literature and organize into a format useful for identifying candidate materials. The third task was to identify candidate materials and begin testing.

Motor/generator and electronic control considerations for energy storage flywheels

NASA Technical Reports Server (NTRS)

Nola, F. J.

1984-01-01

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

Spacecraft Applications of Compact Optical and Mass Spectrometers

NASA Technical Reports Server (NTRS)

Davinic, N. M.; Nagel, D. J.

1995-01-01

Optical spectrometers, and mass spectrometers to a lesser extent, have a long and rich history of use aboard spacecraft. Space mission applications include deep space science spacecraft, earth orbiting satellites, atmospheric probes, and surface landers, rovers, and penetrators. The large size of capable instruments limited their use to large, expensive spacecraft. Because of the novel application of micro-fabrication technologies, compact optical and mass spectrometers are now available. The new compact devices are especially attractive for spacecraft because of their small mass and volume, as well as their low power consumption. Dispersive optical multi-channel analyzers which cover the 0.4-1.1 micrometer wavelength are now commercially available in packages as small as 3 x 6 x 18 mm exclusive of drive and recording electronics. Mass spectrometers as small as 3 x 3 mm, again without electronics, are under development. A variety of compact optical and mass spectrometers are reviewed in this paper. A number of past space applications are described, along with some upcoming opportunities that are likely candidate missions to fly this new class of compact spectrometers.

Active spacecraft potential control system selection for the Jupiter orbiter with probe mission

NASA Technical Reports Server (NTRS)

Beattie, J. R.; Goldstein, R.

1977-01-01

It is shown that the high flux of energetic plasma electrons and the reduced photoemission rate in the Jovian environment can result in the spacecraft developing a large negative potential. The effects of the electric fields produced by this charging phenomenon are discussed in terms of spacecraft integrity as well as charged particle and fields measurements. The primary area of concern is shown to be the interaction of the electric fields with the measuring devices on the spacecraft. The need for controlling the potential of the spacecraft is identified, and a system capable of active control of the spacecraft potential in the Jupiter environment is proposed. The desirability of using this system to vary the spacecraft potential relative to the ambient plasma potential is also discussed. Various charged particle release devices are identified as potential candidates for use with the spacecraft potential control system. These devices are evaluated and compared on the basis of system mass, power consumption, and system complexity and reliability.

Spacecraft Charging in Geostationary Transfer Orbit

NASA Technical Reports Server (NTRS)

Parker, Linda Neergaard; Minow, Joseph I.

2014-01-01

The 700 km x 5.8 Re orbit of the two Van Allen Probes spacecraft provide a unique opportunity to investigate spacecraft charging in geostationary transfer orbits. We use records from the Helium Oxygen Proton Electron (HOPE) plasma spectrometer to identify candidate surface charging events based on the "ion line" charging signature in the ion records. We summarize the energetic particle environment and the conditions necessary for charging to occur in this environment. We discuss the altitude, duration, and magnitude of events observed in the Van Allen Probes from the beginning of the mission to present time. In addition, we explore what information the dual satellites provide on the spatial and temporal variations in the charging environments.

Resources for Radiation Test Data

NASA Technical Reports Server (NTRS)

O'Bryan, Martha V.; Casey, Megan C.; Lauenstein, Jean-Marie; LaBel, Ken

2016-01-01

The performance of electronic devices in a space radiation environment is often limited by susceptibility to single-event effects (SEE), total ionizing dose (TID), and displacement damage (DD). Interpreting the results of SEE, TID, and DD testing of complex devices is quite difficult given the rapidly changing nature of both technology and the related radiation issues. Radiation testing is performed to establish the sensitivities of candidate spacecraft electronics to single-event upset (SEU), single-event latchup (SEL), single-event gate rupture (SEGR), single-event burnout (SEB), single-event transients (SETs), TID, and DD effects. Knowing where to search for these test results is a valuable resource for the aerospace engineer or spacecraft design engineer. This poster is intended to be a resource tool for finding radiation test data.

Simulated space environmental effects on a polyetherimide and its carbon fiber-reinforced composites

NASA Technical Reports Server (NTRS)

Kern, Kristen T.; Stancil, Phillip C.; Harries, Wynford L.; Long, Edward R., Jr.; Thibeault, Sheila A.

1993-01-01

The selection of materials for spacecraft construction requires identification of candidate materials which can perform reliably in the space environment. Understanding the effects of the space environment on the materials is an important step in the selection of candidate materials. This work examines the effects of energetic electrons, thermal cycling, electron radiation in conjunction with thermal cycling, and atomic oxygen on a thermoplastic polyetherimide and its carbon-fiber-reinforced composites. Composite materials made with non-sized fibers as well as materials made with fibers sized with an epoxy were evaluated. The mechanical and thermomechanical properties of the materials were studied and spectroscopic techniques were used to investigate the mechanisms for the observed effects. Considerations for future material development are suggested.

Thermo-Optical and Mechanical Property Testing of Candidate Solar Sail Materials

NASA Technical Reports Server (NTRS)

Hollerman, WIlliam A.; Stanaland, T. L.; Womack, F.; Edwards, David; Hubbs, Whitney; Semmel, Charles

2003-01-01

Solar sailing is a unique form of propulsion where a spacecraft gains momentum from incident photons. Since sails are not limited by reaction mass, they provide continual acceleration, reduced only by the lifetime of the lightweight film in the space environment and the distance to the Sun. Practical solar sails can expand the number of possible missions, enabling new concepts that are difficult by conventional means. The National Aeronautics and Space Administration's Marshall Space Flight Center (MSFC) is concentrating research into the utilization of ultra-lightweight materials for spacecraft propulsion. Solar sails are generally composed of a highly reflective metallic front layer, a thin polymeric substrate, and occasionally a highly emissive back surface. The Space Environmental Effects Team at MSFC is actively characterizing candidate sails to evaluate the thermo-optical and mechanical properties after exposure to electrons. This poster will discuss the preliminary results of this research.

Evaluation and comparison of alternative designs for water/solid-waste processing systems for spacecraft

NASA Technical Reports Server (NTRS)

Spurlock, J. M.

1975-01-01

Promising candidate designs currently being considered for the management of spacecraft solid waste and waste-water materials were assessed. The candidate processes were: (1) the radioisotope thermal energy evaporation/incinerator process; (2) the dry incineration process; and (3) the wet oxidation process. The types of spacecraft waste materials that were included in the base-line computational input to the candidate systems were feces, urine residues, trash and waste-water concentrates. The performance characteristics and system requirements for each candidate process to handle this input and produce the specified acceptable output (i.e., potable water, a storable dry ash, and vapor phase products that can be handled by a spacecraft atmosphere control system) were estimated and compared. Recommendations are presented.

Space Environmental Effects on Candidate Solar Sail Materials

NASA Technical Reports Server (NTRS)

Edwards, David L.; Nehls, Mary; Semmel, Charles; Hovater, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

2004-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted ot a solar sail can be increased, up to a factor of two, if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (L1) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager and the L1 Diamond. The Environmental Effects Group at NASA's Marshall Space Flight Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar, Teonex, and CP1 (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were characterized. The contribution of Near Ultraviolet (NUV) radiation combined with electron and proton radiation was also investigated.

(abstract) Electronic Packaging for Microspacecraft Applications

NASA Technical Reports Server (NTRS)

Wasler, David

1993-01-01

The intent of this presentation is to give a brief look into the future of electronic packaging for microspacecraft applications. Advancements in electronic packaging technology areas have developed to the point where a system engineer's visions, concepts, and requirements for a microspacecraft can now be a reality. These new developments are ideal candidates for microspacecraft applications. These technologies are capable of bringing about major changes in how we design future spacecraft while taking advantage of the benefits due to size, weight, power, performance, reliability , and cost. This presentation will also cover some advantages and limitations of surface mount technology (SMT), multichip modules (MCM), and wafer scale integration (WSI), and what is needed to implement these technologies into microspacecraft.

Solar Wind Electron Interaction with the Dayside Lunar Surface and Crustal Magnetic Fields: Evidence for Precursor Effects

NASA Technical Reports Server (NTRS)

Halekas, Jasper S.; Poppe, A.; Delory, G. T.; Farrell, W. M.; Horanyi, M.

2012-01-01

Electron distributions measured by Lunar Prospector above the dayside lunar surface in the solar wind often have an energy dependent loss cone, inconsistent with adiabatic magnetic reflection. Energy dependent reflection suggests the presence of downward parallel electric fields below the spacecraft, possibly indicating the presence of a standing electrostatic structure. Many electron distributions contain apparent low energy (<100 eV) upwardgoing conics (58% of the time) and beams (12% of the time), primarily in regions with non-zero crustal magnetic fields, implying the presence of parallel electric fields and/or wave-particle interactions below the spacecraft. Some, but not all, of the observed energy dependence comes from the energy gained during reflection from a moving obstacle; correctly characterizing electron reflection requires the use of the proper reference frame. Nonadiabatic reflection may also play a role, but cannot fully explain observations. In cases with upward-going beams, we observe partial isotropization of incoming solar wind electrons, possibly indicating streaming and/or whistler instabilities. The Moon may therefore influence solar wind plasma well upstream from its surface. Magnetic anomaly interactions and/or non-monotonic near surface potentials provide the most likely candidates to produce the observed precursor effects, which may help ensure quasi-neutrality upstream from the Moon.

Ground radiation tests and flight atomic oxygen tests of ITO protective coatings for Galileo Spacecraft

NASA Technical Reports Server (NTRS)

Bouquet, Frank L.; Maag, Carl R.

1986-01-01

Radiation simulation tests (protons and electrons) were performed along with atomic oxygen flight tests aboard the Shuttle to space qualify the surface protective coatings. The results, which contributed to the selection of indium-tin-oxide (ITO) coated polyester as the material for the thermal blankets of the Galileo Spacecraft, are given here. Two candidate materials, polyester and Fluorglas, were radiation-tested to determine changes at simulated Jovian radiation levels. The polyester exhibited a smaller weight loss (2.8) than the Fluorglas (8.8 percent). Other changes of polyester are given. During low-earth orbit, prior to transit to Jupiter, the thermal blankets would be exposed to atomic oxygen. Samples of uncoated and ITO-coated polyesters were flown on the Shuttle. Qualitative results are given which indicated that the ITO coating protected the underlying polyester.

Solar Sail Material Performance Property Response to Space Environmental Effects

NASA Technical Reports Server (NTRS)

Edwards, David L.; Semmel, Charles; Hovater, Mary; Nehls, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

2004-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two, if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (Ll) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager and the L1 Diamond. The Environmental Effects Group at NASA s Marshall Space Flight Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar[TM], Teonex[TM], and CPl (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were characterized. The contribution of Near Ultraviolet (NUV) radiation combined with electron and proton radiation was also investigated.

Solar Sail Material Performance Property Response to Space Environmental Effects

NASA Technical Reports Server (NTRS)

Edwards, David L.; Semmel, Charles; Hovater, Mary; Nehls, Mary; Gray, Perry; Hubbs, Whitney; Wertz, George

2004-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) continues research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two if the sun-facing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. Near term solar sail propelled science missions are targeting the Lagrange point 1 (L1) as well as locations sunward of L1 as destinations. These near term missions include the Solar Polar Imager' and the L1 Diamond '. The Environmental Effects Group at NASA's Marshall Space Fliglit Center (MSFC) continues to actively characterize solar sail material in preparation for these near term solar sail missions. Previous investigations indicated that space environmental effects on sail material thermo-optical properties were minimal and would not significantly affect the propulsion efficiency of the sail3-'. These investigations also indicated that the sail material mechanical stability degrades with increasing radiation exposure. This paper will further quantify the effect of space environmental exposure on the mechanical properties of candidate sail materials. Candidate sail materials for these missions include Aluminum coated Mylar TM, Teonexm, and CP1 (Colorless Polyimide). These materials were subjected to uniform radiation doses of electrons and protons in individual exposures sequences. Dose values ranged from 100 Mrads to over 5 Grads. The engineering performance property responses of thermo-optical and mechanical properties were characterized. The contribution of Near Ultraviolet (NUV) radiation combined with electron and proton radiation was also investigated. Conclusions will be presented providing a gauge of measure for engineering performance stability for sails operating in the L1 space environment.

Formation Flying for Distributed InSAR

NASA Technical Reports Server (NTRS)

Scharf, Daniel P.; Murray, Emmanuell A.; Ploen, Scott R.; Gromov, Konstantin G.; Chen, Curtis W.

2006-01-01

We consider two spacecraft flying in formation to create interferometric synthetic aperture radar (InSAR). Several candidate orbits for such in InSar formation have been previously determined based on radar performance and Keplerian orbital dynamics. However, with out active control, disturbance-induced drift can degrade radar performance and (in the worst case) cause a collision. This study evaluates the feasibility of operating the InSAR spacecraft as a formation, that is, with inner-spacecraft sensing and control. We describe the candidate InSAR orbits, design formation guidance and control architectures and algorithms, and report the (Delta)(nu) and control acceleration requirements for the candidate orbits for several tracking performance levels. As part of determining formation requirements, a formation guidance algorithm called Command Virtual Structure is introduced that can reduce the (Delta)(nu) requirements compared to standard Leader/Follower formation approaches.

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

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

Evaluation and Selection of Replacement Thermal Control Materials for the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline A.; Hansen, Patricia A.; McClendon, Mark W.; Dever, Joyce A.; Triolo, Jack J.

1998-01-01

The mechanical and optical properties of the metallized Teflon(Registered Trademark) FEP thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. A Failure Review Board was established to investigate the damage to the MLI and identify a replacement material. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain structural integrity for at least ten years. Ten candidate materials were selected and exposed to ten-year HST-equivalent doses of simulated orbital environments. Samples of the candidates were exposed sequentially to low and high energy electrons and protons, atomic oxygen, x-ray radiation, ultraviolet radiation and thermal cycling. Following the exposures, the mechanical integrity and optical properties of the candidates were investigated using Optical Microscopy, Scanning Electron Microscopy (SEM), and a Laboratory Portable Spectroreflectometer (LPSR). Based on the results of these simulations and analyses, the FRB selected a replacement material and two alternates that showed the highest likelihood of providing the requisite thermal properties and surviving for ten years in orbit.q

Communication analysis for the expendable explorer spacecraft

NASA Technical Reports Server (NTRS)

1990-01-01

This report provides the results of communication analysis for the baseline and enhanced performance spacecraft designs proposed for Expendable Explorer Spacecraft (EES) series of missions. Five classes of orbits (Geosynchronous, Circular-28 degree inclination, Polar-90 degree inclination, Sunsynchronous-97 degree inclination, Molniya orbit) and a set of candidate instrument payloads provided by the ESS Study Manager were used to formulate the basis for the ESS Communications Study. The study was performed to assess the feasibility of using Space Network or ground stations for supporting the communications, tracking and data handling of the candidate instruments that are proposed to be launched into the desired orbit.

jsc2017e067268

NASA Image and Video Library

2017-06-06

jsc2017e067268 (06/06/2017) --- New Astronaut Candidate's First Day at NASA's Ellington Field. NASA selected 12 new astronaut candidates, Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Robert Hines, Warren Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins at NASA’s Johnson Space Center in Houston, Texas. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/James Blair)

jsc2017e067275

NASA Image and Video Library

2017-06-06

jsc2017e067275 (06/06/2017) -- New Astronaut Candidate's First Day at NASA's Ellington Field. NASA selected 12 new astronaut candidates, Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Robert Hines, Warren Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins at NASA’s Johnson Space Center in Houston, Texas. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/James Blair)

PIC code modeling of spacecraft charging potential during electron beam injection into a background of neutral gas and plasma, part 1

NASA Technical Reports Server (NTRS)

Koga, J. K.; Lin, C. S.; Winglee, R. M.

1989-01-01

Injections of nonrelativistic electron beams from an isolated equipotential conductor into a uniform background of plasma and neutral gas were simulated using a 2-D electrostatic particle code. The ionization effects on spacecraft charging are examined by including interactions of electrons with neutral gas. The simulations show that the conductor charging potential decreases with increasing neutral background density due to the production of secondary electrons near the conductor surface. In the spacecraft wake, the background electrons accelerated towards the charged spacecraft produce an enhancement of secondary electrons and ions. Simulations run for longer times indicate that the spacecraft potential is further reduced and short wavelength beam-plasma oscillations appear. The results are applied to explain the spacecraft charging potential measured during the SEPAC experiments from Spacelab 1.

Standard spacecraft procurement analysis: A case study in NASA-DoD coordination in space programs. Ph.D. Thesis - Rand Graduate Inst.

NASA Technical Reports Server (NTRS)

Harris, E. D.

1980-01-01

The Space Test Program Standard Satellite (STPSS), a design proposed by the Air Force, and two NASA candidates, the Applications Explorer Mission spacecraft (AEM) and the Multimission Modular Spacecraft (MMS), were considered during the first phase. During the second phase, a fourth candidate was introduced, a larger, more capable AEM (L-AEM), configured by the Boeing Company under NASA sponsorship to meet the specifications jointly agreed upon by NASA and the Air Force. Total program costs for a variety of procurement options, each of which is capable of performing all of the Air Force Space Test Program missions during the 1980-1990 time period, were used as the principal measure for distinguishing among procurement options. Program cost does not provide a basis for choosing among the AEM, STPSS, and MMS spacecraft, given their present designs. The availability of the L-AEM spacecraft, or some very similar design, would provide a basis for minimizing the cost of the Air Force Space Test Program.

Analysis of Martian ionosphere and solar wind electron gas data from the planar retarding potential analyzer on the Viking spacecraft

NASA Technical Reports Server (NTRS)

Mantas, G. P.; Hanson, W. B.

1987-01-01

Approximate expressions for the electron current collected by a planar retarding potential analyzer (RPA) mounted on a moving, conducting, charged spacecraft are derived. They are utilized for the analysis of electron current data obtained by the RPAs on the Viking spacecraft in the ionosphere of Mars and in the disturbed and undisturbed solar wind near this planet. It is shown that contamination currents by photoelectrons emitted from the spacecraft can be distinguished and removed from the signal. Parameters deduced from the analysis of RPA electron sampling data are the multicomponent electron temperatures, the number densities, and the spacecraft potential.

Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

NASA Technical Reports Server (NTRS)

Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

2006-01-01

As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

2017 Astronaut Class

NASA Image and Video Library

2017-06-07

nhq201706070004 (06/07/2017) --- Vice President Mike Pence poses for a group photograph with NASA's 12 new astronaut candidates, Wednesday, June 7, 2017 at NASA’s Johnson Space Center in Houston, Texas. NASA astronaut candidates, standing from left, Robb Kulin, Jonathan Kim, Robert Hines, Warren Hoburg, Matthew Dominick, Kayla Barron, Jessica Watkins, from left kneeling, Francisco Rubio, Loral O’Hara, Jasmin Moghbeli, Zena Cardman, and Raja Chari. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/Bill Ingalls) Original Filename

Ground-Based Testing of Replacement Thermal Control Materials for the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Townsend, Jacqueline A.; Hansen, Patricia A.; McClendon, Mark W.; deGroh, Kim K.; Banks, Bruce A.; Triolo, Jack J.

1998-01-01

The mechanical and optical properties of the metallized Teflon FEP thermal control materials on the Hubble Space Telescope (HST) have degraded over the nearly seven years the telescope has been in orbit. Given the damage to the outer layer of the multi-layer insulation (MLI) that was apparent during the second servicing mission (SM2), the decision was made to replace the outer layer during subsequent servicing missions. A Failure Review Board was established to investigate the damage to the MLI and identify a replacement material. The replacement material had to meet the stringent thermal requirements of the spacecraft and maintain mechanical integrity for at least ten years. Ten candidate materials were selected and exposed to ten-year HST-equivalent doses of simulated orbital environments. Samples of the candidates were exposed sequentially to low and high energy electrons and protons, atomic oxygen, x-ray radiation, ultraviolet radiation and thermal cycling. Following the exposures, the mechanical integrity and optical properties of the candidates were investigated using Optical Microscopy, Scanning Electron Microscopy (SEM), a Laboratory Portable Spectroreflectometer (LPSR) and a Lambda 9 Spectroreflectometer. Based on the results of these simulations and analyses, the Failure Review Board selected a replacement material and two alternates that showed the highest likelihood of providing the requisite thermal properties and surviving for ten years in orbit.

Test and Analysis Capabilities of the Space Environment Effects Team at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Finckenor, M. M.; Edwards, D. L.; Vaughn, J. A.; Schneider, T. A.; Hovater, M. A.; Hoppe, D. T.

2002-01-01

Marshall Space Flight Center has developed world-class space environmental effects testing facilities to simulate the space environment. The combined environmental effects test system exposes temperature-controlled samples to simultaneous protons, high- and low-energy electrons, vacuum ultraviolet (VUV) radiation, and near-ultraviolet (NUV) radiation. Separate chambers for studying the effects of NUV and VUV at elevated temperatures are also available. The Atomic Oxygen Beam Facility exposes samples to atomic oxygen of 5 eV energy to simulate low-Earth orbit (LEO). The LEO space plasma simulators are used to study current collection to biased spacecraft surfaces, arcing from insulators and electrical conductivity of materials. Plasma propulsion techniques are analyzed using the Marshall magnetic mirror system. The micro light gas gun simulates micrometeoroid and space debris impacts. Candidate materials and hardware for spacecraft can be evaluated for durability in the space environment with a variety of analytical techniques. Mass, solar absorptance, infrared emittance, transmission, reflectance, bidirectional reflectance distribution function, and surface morphology characterization can be performed. The data from the space environmental effects testing facilities, combined with analytical results from flight experiments, enable the Environmental Effects Group to determine optimum materials for use on spacecraft.

Interplanetary Radiation and Internal Charging Environment Models for Solar Sails

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Altstatt, Richard L.; Neergaard, Linda F.

2004-01-01

A Solar Sail Radiation Environment (SSRE) model has been developed for characterizing the radiation dose and internal charging environments in the solar wind. The SSRE model defines the 0.01 keV to 1 MeV charged particle environment for use in testing the radiation dose vulnerability of candidate solar sail materials and for use in evaluating the internal charging effects in the interplanetary environment. Solar wind and energetic particle instruments aboard the Ulysses spacecraft provide the particle data used to derive the environments for the high inclination 0.5 AU Solar Polar Imager mission and the 1.0 AU L1 solar sail missions. Ulysses is the only spacecraft to sample high latitude solar wind environments far from the ecliptic plane and is therefore uniquely capable of providing the information necessary for defining radiation environments for the Solar Polar Imager spacecraft. Cold plasma moments are used to derive differential flux spectra based on Kappa distribution functions. Energetic particle flux measurements are used to constrain the high energy, non-thermal tails of the distribution functions providing a comprehensive electron, proton, and helium spectra from less than 0.01 keV to a few MeV.

Relationship between the Geotail spacecraft potential and the magnetospheric electron number density including the distant tail regions

NASA Astrophysics Data System (ADS)

Ishisaka, K.; Okada, T.; Tsuruda, K.; Hayakawa, H.; Mukai, T.; Matsumoto, H.

2001-04-01

The spacecraft potential has been used to derive the electron number density surrounding the spacecraft in the magnetosphere and solar wind. We have investigated the correlation between the spacecraft potential of the Geotail spacecraft and the electron number density derived from the plasma waves in the solar wind and almost all the regions of the magnetosphere, except for the high-density plasmasphere, and obtained an empirical formula to show their relation. The new formula is effective in the range of spacecraft potential from a few volts up to 90 V, corresponding to the electron number density from 0.001 to 50 cm-3. We compared the electron number density obtained by the empirical formula with the density obtained by the plasma wave and plasma particle measurements. On occasions the density determined by plasma wave measurements in the lobe region is different from that calculated by the empirical formula. Using the difference in the densities measured by two methods, we discuss whether or not the lower cutoff frequency of the plasma waves, such as continuum radiation, indicates the local electron density near the spacecraft. Then we applied the new relation to the spacecraft potential measured by the Geotail spacecraft during the period from October 1993 to December 1995, and obtained the electron spatial distribution in the solar wind and magnetosphere, including the distant tail region. Higher electron number density is clearly observed on the dawnside than on the duskside of the magnetosphere in the distant tail beyond 100RE.

Spacecraft surface charging within geosynchronous orbit observed by the Van Allen Probes

DOE PAGES

Sarno-Smith, Lois K.; Larsen, Brian A.; Skoug, Ruth M.; ...

2016-02-27

Using the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments from the Van Allen Probes, we explored the relationship between electron energy fluxes in the eV and keV ranges and spacecraft surface charging. We present statistical results on spacecraft charging within geosynchronous orbit by L and MLT. An algorithm to extract the H+ charging line in the HOPE instrument data was developed to better explore intense charging events. Also, this study explored how spacecraft potential relates to electron number density, electron pressure, electron temperature, thermal electron current, and low-energy ion density between 1 and 210 eV.more » It is demonstrated that it is imperative to use both EFW potential measurements and the HOPE instrument ion charging line for examining times of extreme spacecraft charging of the Van Allen Probes. The results of this study show that elevated electron energy fluxes and high-electron pressures are present during times of spacecraft charging but these same conditions may also occur during noncharging times. Furthermore, we also show noneclipse significant negative charging events on the Van Allen Probes.« less

2017 Astronaut Class

NASA Image and Video Library

2017-06-07

nhq201706070006 (06/07/2017) --- Vice President Mike Pence takes a group selfie with kids that were in attendance during an event where NASA introduced 12 new astronaut candidates, Wednesday, June 7, 2017 at NASA’s Johnson Space Center in Houston, Texas. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/Bill Ingalls)

jsc2017e067164

NASA Image and Video Library

2017-06-07

jsc2017e067164 (06/07/2017) --- United States Vice President Mike Pence congratulates NASA's 12 new astronaut candidates at the agency's Johnson Space Center in Houston Texas. The 2017 astronaut candidate class -- Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Bob Hines, Warren “Woody” Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins – were chosen from amid a record number of people applying. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/James Blair)

jsc2017e067182

NASA Image and Video Library

2017-06-07

jsc2017e067182 (06/07/2017) --- United States Vice President Mike Pence congratulates NASA's 12 new astronaut candidates at the agency's Johnson Space Center in Houston Texas. The 2017 astronaut candidate class -- Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Bob Hines, Warren “Woody” Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins – were chosen from amid a record number of people applying. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/Robert Markowitz)

Overview of SDCM - The Spacecraft Design and Cost Model

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

Using a Genetic Algorithm to Design Nuclear Electric Spacecraft

NASA Technical Reports Server (NTRS)

Pannell, William P.

2003-01-01

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

SA13B-1900 Auroral Charging of the International Space Station

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Chandler, Michael O.; Wright, Kenneth H., Jr.

2011-01-01

Electrostatic potential variations of the International Space Station (ISS) relative to the space plasma environment are dominated by interaction of the negatively grounded 160 volt US photovoltaic power system with the plasma environment in sunlight and inductive potential variations across the ISS structure generated by motion of the vehicle across the Earth's magnetic field. Auroral charging is also a source of potential variations because the 51.6? orbital inclination of ISS takes the vehicle to sufficiently high magnetic latitudes to encounter precipitating electrons during geomagnetic storms. Analysis of auroral charging for small spacecraft or isolated insulating regions on ISS predict rapid charging to high potentials of hundreds of volts but it has been thought that the large capacitance of the entire ISS structure on the order of 0.01 F will limit frame potentials to less than a volt when exposed to auroral conditions. We present three candidate auroral charging events characterized by transient ISS structure potentials varying from approximately 2 to 17 volts. The events occur primarily at night when the solar arrays are unbiased and cannot therefore be due to solar array current collection. ISS potential decreases to more negative values during the events indicating electron current collection and the events are always observed at the highest latitudes along the ISS trajectory. Comparison of the events with integral >30 keV electron flux measurements from NOAA TIROS spacecraft demonstrate they occur within regions of precipitating electron flux at levels consistent with the energetic electron thresholds reported for onset of auroral charging of the DMSP and Freja satellites. In contrast to the DMSP and Freja events, one of the ISS charging events occur in sunlight.

A simulation study of interactions of space-shuttle generated electron beams with ambient plasma and neutral gas

NASA Technical Reports Server (NTRS)

Winglee, Robert M.

1991-01-01

The objective was to conduct large scale simulations of electron beams injected into space. The study of the active injection of electron beams from spacecraft is important, as it provides valuable insight into the plasma beam interactions and the development of current systems in the ionosphere. However, the beam injection itself is not simple, being constrained by the ability of the spacecraft to draw current from the ambient plasma. The generation of these return currents is dependent on several factors, including the density of the ambient plasma relative to the beam density, the presence of neutrals around the spacecraft, the configuration of the spacecraft, and the motion of the spacecraft through the plasma. Two dimensional (three velocity) particle simulations with collisional processes included are used to show how these different and often coupled processes can be used to enhance beam propagation from the spacecraft. To understand the radial expansion mechanism of an electron beam injected from a highly charged spacecraft, two dimensional particle-in-cell simulations were conducted for a high density electron beam injected parallel to magnetic fields from an isolated equipotential conductor into a cold background plasma. The simulations indicate that charge build-up at the beam stagnation point causes the beam to expand radially to the beam electron gyroradius.

A simulation study of interactions of Space-Shuttle generated electron beams with ambient plasma and neutral gas

NASA Technical Reports Server (NTRS)

1991-01-01

The object was to conduct large scale simulations of electron beams injected into space. The study of active injection of electron beams from spacecraft is important since it provides valuable insight into beam-plasma interactions and the development of current systems in the ionosphere. However, the beam injection itself is not simple, being constrained by the ability of the spacecraft to draw return current from the ambient plasma. The generation of these return currents is dependent on several factors, including the density of the ambient plasma relative to the beam density, the presence of neutrals around the spacecraft, the configuration of the spacecraft, and the motion of the spacecraft through the plasma. Two dimensional particle simulations with collisional processes included are used to show how these different and often coupled processes can be utilized to enhance beam propagation from the spacecraft. To understand the radical expansion of mechanism of an electron beam from a highly charged spacecraft, two dimensional particle in cell simulations were conducted for a high density electron beam injected parallel to magnetic fields from an isolated equipotential conductor into a cold background plasma. The simulations indicate that charge buildup at the beam stagnation point causes the beam to expand radially to the beam electron gyroradius.

Development of spacecraft toxic gas removal agents

NASA Technical Reports Server (NTRS)

Moore, R. S.

1974-01-01

The development of agents suitable for removal of CO, NH3, NO2 SO2, and other spacecraft contaminants was approached. An extensive technology review was conducted, yielding a large number of potentially useful materials and/or concepts. Because the two toxic gases of greatest interest, CO and NH3, suggested the use of catalysis principles emphasis was placed on the intestigation of transition metals on various supports. Forty-three materials were prepared or obtained and 25 were tested. Gas chromatographic techniques were used to find seven candidates that effectively managed various combinations of the four toxic gases: none managed all. These candidates included six transition metal-containing preparations and a supported LiOH material. Three commercial charcoals showed some efficiency for the toxic gases and may constitute candidates for enhancement by doping with transition metals.

Turbulence Heating ObserveR - THOR: mission overview and payload summary

NASA Astrophysics Data System (ADS)

Escoubet, C.-Philippe; Voirin, Thomas; Wielders, Arno; Vaivads, Andris; Retino, Alessandro; Khotyaintsev, Yuri; Soucek, Jan; Valentini, Francesco; Chen, Chris; Fazakerley, Andrew; Lavraud, Benoit; Marcucci, Federica; Narita, Yasuhito; Vainio, Rami; Romstedt, Jens; Boudin, Nathalie; Junge, Axel; Osuna, Pedro; Walsh, Andrew

2017-04-01

The Turbulence Heating ObserveR (THOR) mission was selected as one of the three candidates, following the Call for Medium Class Missions M4 by the European Space Agency, with a launch planned in 2026. THOR is the first mission ever flown in space dedicated to plasma turbulence. THOR will lead to an understanding of the basic plasma heating and particle energization processes, of their effect on different plasma species and of their relative importance in different turbulent regimes. The THOR mission features one single spinning spacecraft, with the spin axis pointing toward the Sun, and 10 state-of-the-art scientific instruments, measuring electromagnetic fields and waves and electrons and ions at the highest spatial and temporal resolution ever achieved. THOR focuses on particular regions: pristine solar wind, Earth's bow shock and interplanetary shocks, and compressed solar wind regions downstream of shocks, that will be observed with three different orbits of 6 x 15 RE, 6 x 25 RE and 6 x 45 RE. These regions are selected because of their differing turbulent fluctuation characteristics, and reflect similar astrophysical environments. The THOR mission, the conceptual design of the spacecraft and a summary of the payload will be presented. Furthermore, driving requirements and their implications for the spacecraft like Electromagnetic Compatibility and cleanliness will be discussed.

Electromagnetic plasma particle simulations on Solar Probe Plus spacecraft interaction with near-Sun plasma environment

NASA Astrophysics Data System (ADS)

Miyake, Yohei; Usui, Hideyuki

It is necessary to predict the nature of spacecraft-plasma interactions in extreme plasma conditions such as in the near-Sun environment. The spacecraft environment immersed in the solar corona is characterized by the small Debye length due to dense (7000 mathrm{/cc}) plasmas and a large photo-/secondary electron emission current emitted from the spacecraft surfaces, which lead to distinctive nature of spacecraft-plasma interactions [1,2,3]. In the present study, electromagnetic field perturbation around the Solar Probe Plus (SPP) spacecraft is examined by using our original EM-PIC (electromagnetic particle-in-cell) plasma simulation code called EMSES. In the simulations, we consider the SPP spacecraft at perihelion (0.04 mathrm{AU} from the Sun) and important physical effects such as spacecraft charging, photoelectron and secondary electron emission, solar wind plasma flow including the effect of spacecraft orbital velocity, and the presence of a background magnetic field. Our preliminary results show that both photoelectrons and secondary electrons from the spacecraft are magnetized in a spatial scale of several meters, and make drift motion due the presence of the background convection electric field. This effect leads to non-axisymmetric distributions of the electron density and the resultant electric potential near the spacecraft. Our simulations predict that a strong (˜ 100 mathrm{mV/m}) spurious electric field can be observed by the probe measurement on the spacecraft due to such a non-axisymmetric effect. We also confirm that the large photo-/secondary electron current alters magnetic field intensity around the spacecraft, but the field variation is much smaller than the background magnetic field magnitude (a few mathrm{nT} compared to a few mathrm{mu T}). [1] Ergun et al., textit{Phys. Plasmas}, textbf{17}, 072903, 2010. [2] Guillemant et al., textit{Ann. Geophys.}, textbf{30}, 1075-1092, 2012. [3] Guillemant et al., textit{IEEE Trans. Plasma Sci.}, textbf{41}, 3338-3348, 2013.

Spacecraft potential effects on the Dynamics Explorer 2 satellite

NASA Technical Reports Server (NTRS)

Anderson, P. C.; Hanson, W. B.; Coley, W. R.; Hoegy, W. R.

1994-01-01

The relationship between the plasma environment and spacecraft potential is examined for the Dynamics Explorer 2 (DE 2) spacecraft in an attempt to improve the accuracy of ion drift measurements by the retarding potential analyzer (RPA). Because of the DE 2 orbit characteristics (apogee near 1000 km and perigee near 300 km) and the configuration of conducting surfaces on the spacecraft, thermal electrons and ions constituted the only significant contributions to the charging currents to the spacecraft surface for the majority of geophysical conditions encountered. The geomagnetic field had considerable effect on the spacecraft potential due to magnetic field confinement of the electrons as well as to the V x B electric field resulting from the movement of the spacecraft across magnetic field lines. Using a database of inferred spacecraft potentials from the RPA, measured electron temperatures from the Langmuir probe (LANG), and calculated V x B electric fields, we derive an algorithm for determining the spacecraft potential (at the location of the RPA on the spacecraft) for any point of the DE 2 orbit. Knowledge of the spacecraft potential subsequently allows us to retrieve relatively accurate ion drifts from the RPA data.

Hard X-ray spectrum of Cygnus X-1

NASA Technical Reports Server (NTRS)

Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Rothschild, R. E.; Marshall, F. E.; Levine, A. M.; Primini, F. A.

1981-01-01

Long-term measurements of the hard X-ray spectrum from 3 keV to 8 MeV of the black-hole candidate Cygnus X-1 in its low state are reported. Observations were made from October 26 to November 18, 1977 with the A2 (Cosmic X-ray) and A4 (Hard X-ray and Low-Energy Gamma-Ray) experiments on board HEAO 1 in the spacecraft's scanning mode. The measured spectrum below 200 keV is found to agree well with previous spectra which have been fit by a model of the Compton scattering of optical or UV photons in a very hot plasma of electron temperature 32.4 keV and optical depth 3.9 or 1.6 for spherical or disk geometry, respectively. At energies above 300 keV, however, flux excess is observed which may be accounted for by a distribution of electron temperatures from 15 to about 100 keV.

Deep Dielectric Charging of Spacecraft Polymers by Energetic Protons

NASA Technical Reports Server (NTRS)

Green, Nelson W.; Dennison, J. R.

2007-01-01

The majority of research in the field of spacecraft charging concentrates on electron charging effects with little discussion of charging by protons. For spacecraft orbiting in the traditional LEO and GEO environments this emphasis on electrons is appropriate since energetic electrons are the dominant species in those orbits. But for spacecraft in orbits within the inner radiation belts or for interplanetary and lunar space probes, proton charging (center dot) effects may also be of concern. To examine bulk spacecraft charging effects in these environments several typical highly insulating spacecraft polymers were exposed to energetic protons (center dot) with energies from 1 Me V to lO Me V to simulate protons from the solar wind and from solar energetic proton events. Results indicate that effects in proton charged dielectrics are distinctly different than those observed due to electron charging. In most cases, the positive surface potential continued to increase for periods on the order of minutes to a day, followed by long time scale decay at rates similar to those observed for electron charging. All samples charged to positive potentials with substantially lower magnitudes than for equivalent electron doses. Possible explanations for the different behavior of the measured surface potentials from proton irradiation are discussed; these are related to the evolving internal charge distribution from energy dependent electron and proton transport, electron emission, charge migration due to dark current and radiation induced conductivity, and electron capture by embedded protons.

Peculiarities of Spacecraft Photoelectron Shield Formation in Magnetic Field

NASA Astrophysics Data System (ADS)

Veselov, Mikhail; Chugunin, Dmitriy

Traditionally, the current balance equations for a spacecraft in space plasma rely on the electric field of positively charged spacecraft. Equilibrium potential V is derived from currents outward and toward the spacecraft body. The currents are in turn functions of V. However, in reality photoelectrons move in both the electric field of the spacecraft and the Earth or the interplanetary magnetic field. This causes an anisotropic distribution of photoelectrons along a magnetic field line with the characteristic size of the order of several photoelectron gyro-radii. As a result, confinement of photoelectrons in the spacecraft-related electric field is much longer. Thus, a fraction of returned photoelectrons in the electron current toward the spacecraft can be rather great and may even dominate several times over the ambient electrons’ fraction. Modeled ph-electron trajectories as well as general photoelectron shield distribution around spacecraft are represented, and comparison of experimental data on the electron density with the magnetic flux tube model is discussed.

Radiation effects on electronic parts

NASA Technical Reports Server (NTRS)

Johnson, W. S.

1971-01-01

A search of literature concerning the long term effects of nuclear radiation on electronic parts was conducted to determine the effects of radiation fields encountered on deep space missions to parts used in the Pioneer Spacecraft. Topics discussed include: the various types of radiation the spacecraft will encounter, effects of radiation on electronic parts, and estimates of the damage thresholds for transistors and integrated circuits used on the Pioneer Spacecraft.

Chaos in Kepler's Multiple Planet Systems and K2s Observations of the Atmospheres of Uranus Neptune

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.

2016-01-01

More than one-third of the 4700 planet candidates found by NASA's Kepler spacecraft during its prime mission are associated with target stars that have more than one planet candidate, and such "multis" account for the vast majority of candidates that have been verified as true planets. The large number of multis tells us that flat multiplanet systems like our Solar System are common. Virtually all of the candidate planetary systems are stable, as tested by numerical integrations that assume a physically motivated mass-radius relationship, but some of the systems lie in chaotic regions close to instability. The characteristics of some of the most interesting confirmed Kepler multi-planet systems will be discussed. The Kepler spacecraft's 'second life' in theK2 mission has allowed it to obtain long time-series observations of Solar System targets, including the giant planets Uranus & Neptune. These observations show variability caused by the chaotic weather patterns on Uranus & Neptune.

jsc2017e067186

NASA Image and Video Library

2017-06-07

jsc2017e067186 (06/07/2017) --- United States Vice President Mike Pence delivers remarks during an event where 12 new NASA astronaut candidates were introduced; Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Robert Hines, Warren Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins at NASA’s Johnson Space Center in Houston, Texas. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/Robert Markowitz)

jsc2017e067161

NASA Image and Video Library

2017-06-07

jsc2017e067161 06/07/2017) --- Robert Lightfoot, NASA's Acting Administrator, delivers remarks during an event where 12 new NASA astronaut candidates were introduced; Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Robert Hines, Warren Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins at NASA’s Johnson Space Center in Houston, Texas. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/James Blair)

Performance Testing of a Photocatalytic Oxidation Module for Spacecraft Cabin Atmosphere Revitalization

NASA Technical Reports Server (NTRS)

Perry, Jay L.; Abney, Morgan B.; Frederick, Kenneth R.; Scott, Joseph P.; Kaiser, Mark; Seminara, Gary; Bershitsky, Alex

2011-01-01

Photocatalytic oxidation (PCO) is a candidate process technology for use in high volumetric flow rate trace contaminant control applications in sealed environments. The targeted application for PCO as applied to crewed spacecraft life support system architectures is summarized. Technical challenges characteristic of PCO are considered. Performance testing of a breadboard PCO reactor design for mineralizing polar organic compounds in a spacecraft cabin atmosphere is described. Test results are analyzed and compared to results reported in the literature for comparable PCO reactor designs.

NASA's New Astronauts to Conduct Research Off the Earth , For the Earth and Deep Space Missions

NASA Image and Video Library

2017-06-07

After receiving a record-breaking number of applications to join an exciting future of space exploration, NASA has selected its largest astronaut class since 2000. Rising to the top of more than 18,300 applicants, NASA chose 12 women and men as the agency’s new astronaut candidates. Vice President Mike Pence joined Acting NASA Administrator Robert Lightfoot, Johnson Space Center Director Ellen Ochoa, and Flight Operations Director Brian Kelly to welcome the new astronaut candidates during an event June 7 at the agency’s Johnson Space Center in Houston. The astronaut candidates will return to Johnson in August to begin two years of training. Then they could be assigned to any of a variety of missions: performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and departing for deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket.

Secondary electron generation, emission and transport: Effects on spacecraft charging and NASCAP models

NASA Technical Reports Server (NTRS)

Katz, Ira; Mandell, Myron; Roche, James C.; Purvis, Carolyn

1987-01-01

Secondary electrons control a spacecraft's response to a plasma environment. To accurately simulate spacecraft charging, the NASA Charging Analyzer Program (NASCAP) has mathematical models of the generation, emission and transport of secondary electrons. The importance of each of the processes and the physical basis for each of the NASCAP models are discussed. Calculations are presented which show that the NASCAP formulations are in good agreement with both laboratory and space experiments.

Plasma density enhancements created by the ionization of the Earth's upper atmosphere by artificial electron beams

NASA Technical Reports Server (NTRS)

Neubert, Torsten; Banks, Peter M.

1990-01-01

Analytical calculations and experimental observations relating to the interaction with the Earth's upper atmosphere of electron beams emitted from low altitude spacecraft are presented. The problem is described by two coupled nonlinear differential equations in the up-going (along a magnetic field line) and down-going differential energy flux. The equations are solved numerically, using the MSIS atmospheric model and the IRI ionospheric model. The results form the model compare well with recent observations from the CHARGE 2 sounding rocket experiment. Two aspects of the beam-neutral atmosphere interaction are discussed. First, the limits on the electron beam current that can be emitted from a spacecraft without substantial spacecraft charging are investigated. This is important because the charging of the spacecraft to positive potentials limits the current and the escape energy of the beam electrons and thereby limits the ionization of the neutral atmosphere. As an example, we find from CHARGE 2 observations and from the model calculations that below about 180 km, secondary electrons generated through the ionization of the neutral atmosphere by 1 to 10 keV electron beams from sounding rockets, completely balance the beam current, thereby allowing the emission of very high beam currents. Second, the amount of plasma production in the beam-streak is discussed. Results are shown for selected values of the beam energy, spacecraft velocity, and spacecraft altitude.

Development of electrical test procedures for qualification of spacecraft against EID. Volume 2: Review and specification of test procedures

NASA Technical Reports Server (NTRS)

Wilkenfeld, J. M.; Harlacher, B. L.; Mathews, D.

1982-01-01

A combined experimental and analytical program to develop system electrical test procedures for the qualification of spacecraft against damage produced by space-electron-induced discharges (EID) occurring on spacecraft dielectric outer surfaces is described. A review and critical evaluation of possible approaches to qualify spacecraft against space electron-induced discharges (EID) is presented. A variety of possible schemes to simulate EID electromagnetic effects produced in spacecraft was studied. These techniques form the principal element of a provisional, recommended set of test procedures for the EID qualification spacecraft. Significant gaps in our knowledge about EID which impact the final specification of an electrical test to qualify spacecraft against EID are also identified.

Mirroring of fast solar flare electrons on a downstream corotating interaction region

NASA Technical Reports Server (NTRS)

Anderson, K. A.; Sommers, J.; Lin, R. P.; Pick, M.; Chaizy, P.; Murphy, N.; Smith, E. J.; Phillips, J. L.

1995-01-01

We discuss an example of confinement of fast solar electrons by a discrete solar wind-interplanetary magnetic field structure on February 22, 1991. The structure is about 190,000 km in width and is clearly defined by changes in the direction of the magnetic field at the Ulysses spacecraft. This structure carries electrons moving toward the Sun as well as away from the Sun. A loss cone in the angular distribution of the fast electrons shows that mirroring, presumably magnetic, takes place downstream from the spacecraft. Following passage of this narrow structure, the return flux vanishes for 21 min after which time the mirroring resumes and persists for several hours. We identify the enhanced magnetic field region lying downstream from the Ulysses spacecraft that is responsible for the mirroring to be a corotating stream interaction region. Backstreaming suprathermal electron measurements by the Los Alamos National Laboratory plasma experiment on the Ulysses spacecraft support this interpretation.

Finite Gyroradius Effects in the Electron Outflow of Asymmetric Magnetic Reconnection

NASA Technical Reports Server (NTRS)

Norgren, C.; Graham, D. B.; Khotyaintsev, Yu. V.; Andre, M.; Vaivads, A.; Chen, Li-Jen; Lindqvist, P.-A.; Marklund, G. T.; Ergun, R. E.; Magnes, W.;

Installing Electronics in Juno Vault

NASA Image and Video Library

2010-12-16

Technicians install components that will aid with guidance, navigation and control of NASA Juno spacecraft. Like most of Juno sensitive electronics, these components are situated within the spacecraft titanium radiation vault.

Coincidence probabilities for spacecraft gravitational wave experiments - Massive coalescing binaries

NASA Technical Reports Server (NTRS)

Tinto, Massimo; Armstrong, J. W.

1991-01-01

Massive coalescing binary systems are candidate sources of gravitational radiation in the millihertz frequency band accessible to spacecraft Doppler tracking experiments. This paper discusses signal processing and detection probability for waves from coalescing binaries in the regime where the signal frequency increases linearly with time, i.e., 'chirp' signals. Using known noise statistics, thresholds with given false alarm probabilities are established for one- and two-spacecraft experiments. Given the threshold, the detection probability is calculated as a function of gravitational wave amplitude for both one- and two-spacecraft experiments, assuming random polarization states and under various assumptions about wave directions. This allows quantitative statements about the detection efficiency of these experiments and the utility of coincidence experiments. In particular, coincidence probabilities for two-spacecraft experiments are insensitive to the angle between the directions to the two spacecraft, indicating that near-optical experiments can be done without constraints on spacecraft trajectories.

jsc2017e067167

NASA Image and Video Library

2017-06-07

jsc2017e067167 (06/07/2017)--- Ellen Ochoa, Director of the Johnson Space Center delivers remarks during an event where 12 new NASA astronaut candidates were introduced; Kayla Barron, Zena Cardman, Raja Chari, Matthew Dominick, Robert Hines, Warren Hoburg, Jonathan Kim, Robb Kulin, Jasmin Moghbeli, Loral O’Hara, Francisco Rubio and Jessica Watkins at NASA’s Johnson Space Center in Houston, Texas. After completing two years of training, the new astronaut candidates could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on NASA’s new Orion spacecraft and Space Launch System rocket. Photo Credit: (NASA/Robert Markowitz)

Protecting Juno Electronics from Radiation

NASA Image and Video Library

2010-07-12

Technicians installed the special radiation vault for NASA Juno spacecraft on the propulsion module. The radiation vault has titanium walls to protect the spacecraft electronic brain and heart from Jupiter harsh radiation environment.

The association of spacecraft anomalies with electron/proton particle fluxes at different orbits

NASA Astrophysics Data System (ADS)

Yi, K.; Moon, Y. J.

2016-12-01

In this study, we investigate 195 satellite anomaly data from 1998 to 2010 from Satellite News Digest (SND) to understand the association between spacecraft anomaly and space weather condition. The spacecraft anomalies are classified into Attitude & Propulsion, Power, Control, Telemetry, Instrument and unknown. For the investigation we divide these data according to the spacecraft orbit and launched year. Spacecraft's orbits are classified into the following two groups : (1) high altitude and low inclination, and (2) low altitude and high inclination. Launched year of spacecraft are divided into two groups: 1991 1998 and 1999 2007. We examine the association between these anomaly data and daily peak particle (electron and proton) flux data from GOES as well as their occurrence rates. To determine the association, we use two criteria that electron criterion is >10,000 pfu and proton criterion is >100 pfu. Main results from this study are as follows. First, the number of days satisfying the criteria for electron flux has a peak near a week before the anomaly day and decreases from the peak day to the anomaly day, while that for proton flux has a peak near the anomaly day. Second, we found a similar pattern for the mean daily peak particle (electron and proton) flux as a function of day before the anomaly day. Third, an examination of multiple spacecraft anomaly events, which are likely to occur by severe space weather effects, shows that anomalies mostly occur either when electron fluxes are in the declining stage, or when daily proton peak fluxes are strongly enhanced. Fourth, the time delay between the anomaly day and the day having the highest daily peak electron flux for the recent launching period (1999-2007) is noticeably larger than those for the older periods, implying that the anomaly characteristics associated with electron flux change with time.

Characterization of Space Environmental Effects on Candidate Solar Sail Material

NASA Technical Reports Server (NTRS)

Edwards, David; Hubbs, Whitney; Stanaland, Tesia; Munafo, Paul M. (Technical Monitor)

2002-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) is concentrating research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A solar sail operates on the principle that photons, originating from the sun, impart pressure to the sail and therefore provide a source for spacecraft propulsion. The pressure imparted to a solar sail can be increased, up to a factor of two if the sunfacing surface is perfectly reflective. Therefore, these solar sails are generally composed of a highly reflective metallic sun-facing layer, a thin polymeric substrate and occasionally a highly emissive back surface. The Space Environmental Effects Team, at MSFC, is actively characterizing candidate solar sail material to evaluate the thermo-optical and mechanical properties after exposure to radiation environments simulating orbital environments. This paper describes the results of three candidate materials after exposure to a simulated Geosynchronous Transfer Orbit (GTO). This is the first known characterization of solar sail material exposed to space simulated radiation environments. The technique of radiation dose versus material depth profiling was used to determine the orbital equivalent exposure doses. The solar sail exposure procedures and results of the material characterization will be discussed.

Interplanetary charged particle models (1974). [and the effects of cosmic exposure upon spacecraft and spacecraft components

NASA Technical Reports Server (NTRS)

Divine, N.

1975-01-01

The design of space vehicles for operation in interplanetary space is given, based on descriptions of solar wind, solar particle events, and galactic cosmic rays. A state-of-the-art review is presented and design criteria are developed from experiment findings aboard interplanetary and high-altitude earth-orbiting spacecraft. Solar cells were found to be particularly sensitive. Solar protons may also impact the reliability of electric propulsion systems and spacecraft surfaces, as well as causing interference, detector saturation, and spurious signals. Galactic cosmic-ray impact can lead to similar electronic failure and interference and may register in photographic films and other emulsions. It was concluded that solar wind electron measurements might result from differential charging when shadowed portions of the spacecraft acquired a negative charge from electron impact.

A Spacecraft Charging Capability for SXTF.

DTIC Science & Technology

1979-01-17

surfaces can charge up. ’Iiiis differential charging of satellite surfaces can cause vacutum sparks , and dielectric breakdowns, and wi 11 effect the S...times required to reach steady charge state in the spacecraft internal dielectrics upon electron irradiation. In space , typical times (order of magni...WORDS (Continue on reverse side it necessary end Identify by block nunmber) Spacecraft charging Dielectric breakdown SGEMP Electron accelerators

Characterization of Space Environmental Effects on Candidate Solar Sail Material

NASA Technical Reports Server (NTRS)

Edwards, David; Hubbs, Whitney; Stanaland, Tesia; Altstatt, Richard

2002-01-01

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) is concentrating research into the utilization of photonic materials for spacecraft propulsion. Spacecraft propulsion, using photonic materials, will be achieved using a solar sail. A sail operates on the principle that photons, originating from the sun, impart pressure and provide a source of spacecraft propulsion. The pressure can be increased, by a factor of two if the sun-facing surface is perfectly reflective. Solar sails are generally composed of a highly reflective metallic front layer, a thin polymeric substrate, and occasionally a highly emissive back surface. The Space Environmental Effects Team at MSFC is actively characterizing candidate solar sail materials to evaluate the thermo-optical and mechanical properties after exposure to a simulated Geosynchronous Transfer Orbit (GTO) radiation environment. The technique of radiation dose verses material depth profiling was used to determine the orbital equivalent exposure doses. The solar sail exposure procedures and results of the material characterization will be discussed.

TOPEX satellite concept. TOPEX option study report

NASA Technical Reports Server (NTRS)

Meyer, D. P.; Case, C. M.

1982-01-01

Candidate bus equipment from the Viking, Applications Explorer Mission, and Small Scientific Satellite programs for application to the TOPEX mission options is assessed. Propulsion module equipment and subsystem candidates from the Applications Explorer Mission satellites and the Small Scientific Satellite spacecraft are evaluated for those TOPEX options. Several subsystem concepts appropriate to the TOPEX options are described. These descriptions consider performance characteristics of the subsystems. Cost and availability information on the candidate equipment and subsystems are also provided.

Tracking and Data Relay Satellite System (TDRSS) Support of User Spacecraft without TDRSS Transponders

NASA Technical Reports Server (NTRS)

Jackson, James A.; Marr, Greg C.; Maher, Michael J.

1995-01-01

NASA GSFC VNS TSG personnel have proposed the use of TDRSS to obtain telemetry and/or S-band one-way return Doppler tracking data for spacecraft which do not have TDRSS-compatible transponders and therefore were never considered candidates for TDRSS support. For spacecraft with less stable local oscillators (LO), one-way return Doppler tracking data is typically of poor quality. It has been demonstrated using UARS, WIND, and NOAA-J tracking data that the simultaneous use of two TDRSS spacecraft can yield differenced one-way return Doppler data of high quality which is usable for orbit determination by differencing away the effects of oscillator instability.

Unmanned planetary spacecraft chemical rocket propulsion.

NASA Technical Reports Server (NTRS)

Burlage, H., Jr.; Gin, W.; Riebling, R. W.

1972-01-01

Review of some chemical propulsion technology advances suitable for future unmanned spacecraft applications. Discussed system varieties include liquid space-storable propulsion systems, advanced liquid monopropellant systems, liquid systems for rendezvous and landing applications, and low-thrust high-performance solid-propellant systems, as well as hybrid space-storable systems. To optimize the performance and operational characteristics of an unmanned interplanetary spacecraft for a particular mission, and to achieve high cost effectiveness of the entire system, it is shown to be essential that the type of spacecraft propulsion system to be used matches, as closely as possible the various requirements and constraints. The systems discussed are deemed to be the most promising candidates for some of the anticipated interplanetary missions.

Excess science accommodation capabilities and excess performance capabilities assessment for Mars Geoscience and Climatology Orbiter: Extended study

NASA Technical Reports Server (NTRS)

Clark, K.; Flacco, A.; Kaskiewicz, P.; Lebsock, K.

1983-01-01

The excess science accommodation and excess performance capabilities of a candidate spacecraft bus for the Mars Geoscience and Climatology Orbiter MGCO mission are assessed. The appendices are included to support the conclusions obtained during this contract extension. The appendices address the mission analysis, the attitude determination and control, the propulsion subsystem, and the spacecraft configuration.

Atomic oxygen effects on candidate coatings for long-term spacecraft in low earth orbit

NASA Technical Reports Server (NTRS)

Lan, E. H.; Smith, Charles A.; Cross, J. B.

1988-01-01

Candidate atomic oxygen protective coatings for long-term low Earth orbit (LEO) spacecraft were evaluated using the Los Alamos National Laboratory O-atom exposure facility. The coatings studied include Teflon, Al2O3, SiO2, and SWS-V-10, a silicon material. Preliminary results indicate that sputtered PTFE Teflon (0.1 micrometers) has a fluence lifetime of 10 to the 19th power O-atoms/cm (2), and sputtered silicon dioxide (0.1 micrometers), aluminum oxide (0.1 micrometers), and SWS-V-10, a silicone, (4 micrometers) have fluence lifetimes of 10 to the 20th power to 10 to the 21st power O-atoms/cm (2). There are large variations in fluence lifetime data for these coatings.

Searching for organics on the dwarf planet Ceres

NASA Astrophysics Data System (ADS)

Nayak, Michael

The Herschel Space Observatory recently detected the presence of water vapor in observations of Ceres, bringing it into the crosshairs of the search for the building blocks of life in the solar system. I present a mission concept designed in collaboration with the NASA Ames Research Center for a two-probe mission to the dwarf planet Ceres, utilizing a pair of small low-cost spacecraft. The primary spacecraft will carry both a mass and an infrared spectrometer to characterize the detected vapor. Shortly after its arrival a second and largely similar spacecraft will impact Ceres to create an impact ejecta "plume" timed to enable a rendezvous and sampling by the primary spacecraft. This enables additional subsurface chemistry, volatile content and material characterization, and new science complementary to the Dawn spacecraft, the first to arrive at Ceres. Science requirements, candidate instruments, rendezvous trajectories, spacecraft design and comparison with Dawn science are detailed.

Electromagnetic interaction of spacecraft with ambient environment

NASA Astrophysics Data System (ADS)

Ku, Hwar-Ching; Silver, David M.

1993-01-01

A model of the midcourse space experiment (MSX) spacecraft and its electromagnetic environment has been developed using the potential of large spacecraft in the Auroral region (POLAR) code. The geometric model has a resolution of 0.341 meters and uses six materials to simulate the electrical surface properties of MSX. The vehicle model includes features such as the major instruments, electronic boxes, radiators, a dewar and open bay, a booster attachment ring, and three different orientations of the solar panels. The electron and ion composition and temperature environment are modeled as a function of the solar activity. Additional parameters include the ram-wake orientation, the hot electron spectrum, day-night-twilight variations, latitudinal variations, and solar panel voltage biasing. Nominal low spacecraft charging cases are described. Calculation with a high peak energetic electron flux produces a ground potential of -180 volts and differential charging as high as 66 volts.

Testing Protocol Proposal to Identify and Evaluate Candidate Materials to Substitute for Silverized Teflon in Thermal Control Applications

NASA Technical Reports Server (NTRS)

Losure, Nancy S.

1996-01-01

Electrostatic discharge (ESD) has been shown to be the primary cause of several glitches in spacecraft operations. It appears that charged particles encountered in the natural environment in certain orbits can collect on the outer surfaces of a spacecraft, building up a charge of several thousand volts. If the potential exceeds the breakdown voltage of the charged material, then an ESD will occur. ESD events involving relatively low voltages, on the order of 100 V, have been shown to damage electronic components. When ESD occurs, electronic and electrical components can be damaged, computer instructions can be garbled, and ablation of material from the spacecraft may occur; degrading both the performance of the thermal control blankets, and the cleanliness of any surfaces on which the detritus becomes deposited. There appear to be six ways to prevent or mitigate the effects of ESD: (1) Choose an orbit where charging is not a problem; (2) Carry extra electromagnetic shielding; (3) Provide redundancy in components and programming; (4) Provide for active dissipation of the charge, by generating a plasma with which to bathe susceptible surfaces; (5) Provide for passive dissipation from a plasma contactors on the susceptible surfaces; and (6) Provide thermal control blankets that do not hold a charge, i.e., that are conductive enough to bleed a charge off harmlessly. These six options are discussed in detail in Losure (1996). Of these six options, number 1 is not always practical, given other requirements of the mission; 2, 3, 4 and 5 will require that extra mass in the form of shielding, etc., be carried by the spacecraft. The most attractive option from a mass and energy point of view seems to be that of finding a material which matches the other performance characteristics of the current thermal control blankets without their tendency to build up an electrostatic charge. The goal of this paper is to describe and justify a testing program which will lead to the approval of materials of this kind.

Thermoelectric Outer Planets Spacecraft (TOPS) electronic packaging and cabling development summary report

NASA Technical Reports Server (NTRS)

Dawe, R. H.; Arnett, J. C.

1974-01-01

Electronic packaging and cabling activities performed in support of the Thermoelectric Outer Planets Spacecraft (TOPS) Advanced Systems Technology (AST) project are detailed. It describes new electronic compartment, electronic assembly, and module concepts, and a new high-density, planar interconnection technique called discrete multilayer (DML). Development and qualification of high density cabling techniques, using small gage wire and microminiature connectors, are also reported.

Design of Power System Architectures for Small Spacecraft Systems

NASA Technical Reports Server (NTRS)

Momoh, James A.; Subramonian, Rama; Dias, Lakshman G.

1996-01-01

The objective of this research is to perform a trade study on several candidate power system architectures for small spacecrafts to be used in NASA's new millennium program. Three initial candidate architectures have been proposed by NASA and two other candidate architectures have been proposed by Howard University. Howard University is currently conducting the necessary analysis, synthesis, and simulation needed to perform the trade studies and arrive at the optimal power system architecture. Statistical, sensitivity and tolerant studies has been performed on the systems. It is concluded from present studies that certain components such as the series regulators, buck-boost converters and power converters can be minimized while retaining the desired functionality of the overall architecture. This in conjunction with battery scalability studies and system efficiency studies have enabled us to develop more economic architectures. Future studies will include artificial neural networks and fuzzy logic to analyze the performance of the systems. Fault simulation studies and fault diagnosis studies using EMTP and artificial neural networks will also be conducted.

Low-Temperature Spacecraft: Challenges/Opportunities

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Modeling and Data Analysis at the CCMC to Determine Threat of Spacecraft Surface Charging in Low Earth Orbit

NASA Astrophysics Data System (ADS)

Rastaetter, L.; Kuznetsova, M. M.; Zheng, Y.; Jordanova, V.; Yu, Y.; Minow, J. I.

2016-12-01

Spacecraft surface charging in Low-Earth Orbit occurs primarily in regions of low plasma density when precipitating electrons drive the spacecraft potential. Sudden changes in electric potentials occur when a spacecraft enters and leaves the sunlit region.At the Community Coordinated Modeling Center, we can employ a multitude of models of the ionosphere-thermosphere and inner magnetosphere to identify regions where spacecraft charging can occur based on thresholds of electron precipitation flux and energy and track the proximity of those areas to positions of satellites of interest. The identified regions will be validated and refined based on satellite observations. This work is in conjunction with the Spacecraft Charging Challenge organized by the GEM Workshop in collaboration with CCMC and the SHIELDS project at LANL.

Probability Analysis for Accidental Impact on Mars by the Micro-Spacecraft Procyon

NASA Astrophysics Data System (ADS)

Funase, Ryu; Yano, Hajime; Kawakatsu, Yasuhiro; Ozaki, Naoya; Nakajima, Shintaro; Shimizu, Yukio

This paper analyzes the impact probability on Mars for the 50kg-class micro-spacecraft PROCYON (PRoximate Object Close flYby with Optical Navigation) in 50 years after its launch. PROCYON, which is mainly developed by the University of Tokyo and the Japan Aerospace Exploration Agency (JAXA), has two missions: the first is the technology demonstration of a micro-spacecraft bus system for deep space exploration and the second is proximity operation by Near-Earth asteroids (NEAs) as the closest flyby distance from a target asteroid is aimed around 30 kilometer. The spacecraft is scheduled to be launched together with Japan’s second asteroid sample return spacecraft "Hayabusa-2" at the end of 2014. Initially PROCYON will be inserted into an Earth resonant trajectory that allows the spacecraft to cruise back to the Earth by solar electric propulsion leveraging. The Earth gravity assist, which is scheduled at the end of 2015, will enable the spacecraft to expand a number of candidate NEAs for flyby operations. At the time of the writing, its candidate NEAs include "2000 DP107", "2010 LJ14" and "2002 AJ29". A miniature ion thruster is mounted on the spacecraft to provide 300muN of thrust with specific impulse of 1200 seconds for deep space maneuver before Earth gravity assist. Considering a small amount of its fuel (about 2 kg of Xenon propellant), PROCYON has no possibility to impact directly on Mars without Earth gravity assist. However, if PROCYON successfully obtains large enough delta-V by the Earth gravity assist at the end of 2015, a possibility of accidental impact on Mars cannot be neglected in order to comply the COSPAR planetary protection requirements for forward contamination. In this paper, we calculate the possibility of accidental impact on Mars after the Earth gravity assist. As the result we conclude that the possibility of Mars impact is negligible within 50 years after its launch.

Spacecraft potential control on ISEE-1

NASA Technical Reports Server (NTRS)

Gonfalone, A.; Pedersen, A.; Fahleson, U. V.; Faelthammar, C. G.; Mozer, F. S.; Torbert, R. B.

1979-01-01

Active control of the potential of the ISEE-1 satellite by the use of electron guns is reviewed. The electron guns contain a special cathode capable of emitting an electron current selectable between 10 to the -8th power and 10 to the -3rd power at energies from approximately .6 to 41 eV. Results obtained during flight show that the satellite potential can be stabilized at a value more positive than the normally positive floating potential. The electron guns also reduce the spin modulation of the spacecraft potential which is due to the aspect dependent photoemission of the long booms. Plasma parameters like electron temperature and density can be deduced from the variation of the spacecraft potential as a function of the gun current. The effects of electron beam emission on other experiments are briefly mentioned.

High Frequency Analyzer (HFA) of Plasma Wave Experiment (PWE) onboard the Arase spacecraft

NASA Astrophysics Data System (ADS)

Kumamoto, Atsushi; Tsuchiya, Fuminori; Kasahara, Yoshiya; Kasaba, Yasumasa; Kojima, Hirotsugu; Yagitani, Satoshi; Ishisaka, Keigo; Imachi, Tomohiko; Ozaki, Mitsunori; Matsuda, Shoya; Shoji, Masafumi; Matsuoka, Aayako; Katoh, Yuto; Miyoshi, Yoshizumi; Obara, Takahiro

2018-05-01

The High Frequency Analyzer (HFA) is a subsystem of the Plasma Wave Experiment onboard the Arase (ERG) spacecraft. The main purposes of the HFA include (1) determining the electron number density around the spacecraft from observations of upper hybrid resonance (UHR) waves, (2) measuring the electromagnetic field component of whistler-mode chorus in a frequency range above 20 kHz, and (3) observing radio and plasma waves excited in the storm-time magnetosphere. Two components of AC electric fields detected by Wire Probe Antenna and one component of AC magnetic fields detected by Magnetic Search Coils are fed to the HFA. By applying analog and digital signal processing in the HFA, the spectrograms of two electric fields (EE mode) or one electric field and one magnetic field (EB mode) in a frequency range from 10 kHz to 10 MHz are obtained at an interval of 8 s. For the observation of plasmapause, the HFA can also be operated in PP (plasmapause) mode, in which spectrograms of one electric field component below 1 MHz are obtained at an interval of 1 s. In the initial HFA operations from January to July, 2017, the following results are obtained: (1) UHR waves, auroral kilometric radiation (AKR), whistler-mode chorus, electrostatic electron cyclotron harmonic waves, and nonthermal terrestrial continuum radiation were observed by the HFA in geomagnetically quiet and disturbed conditions. (2) In the test operations of the polarization observations on June 10, 2017, the fundamental R-X and L-O mode AKR and the second-harmonic R-X mode AKR from different sources in the northern polar region were observed. (3) The semiautomatic UHR frequency identification by the computer and a human operator was applied to the HFA spectrograms. In the identification by the computer, we used an algorithm for narrowing down the candidates of UHR frequency by checking intensity and bandwidth. Then, the identified UHR frequency by the computer was checked and corrected if needed by the human operator. Electron number density derived from the determined UHR frequency will be useful for the investigation of the storm-time evolution of the plasmasphere and topside ionosphere.[Figure not available: see fulltext.

Pneumatic preloaded scanning science launch latch system

NASA Technical Reports Server (NTRS)

Kievit, J. C.

1979-01-01

A relatively simple system using a preloaded pneumatic piston latch with a pyrotechnic valve release was developed. The system was the only candidate that met all the imposed requirements utilizing reliable state-of-art components. The development of the latch system from its first use on Mariner '69 Mars Flyby Spacecraft through its most recent use on the Voyager Spacecraft that will fly to Jupiter and Saturn is reviewed.

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

NASA Technical Reports Server (NTRS)

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

2008-01-01

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

Calculation of secondary-electron escape currents from inclined-spacecraft surfaces in a magnetic field

NASA Technical Reports Server (NTRS)

Laframboise, J. G.

1985-01-01

In low Earth orbit, the geomagnetic field B(vector) is strong enough that secondary electrons emitted from spacecraft surfaces have an average gyroradius much smaller than typical dimensions of large spacecraft. This implies that escape of secondaries will be strongly inhibited on surfaces which are nearly parallel to B(vector), even if a repelling electric field exists outside them. This effect is likely to make an important contribution to the current balance and hence the equilibrium potential of such surfaces, making high voltage charging of them more likely. Numerically calculated escaping secondary electron fluxes are presented for these conditions. For use in numerical spacecraft charging simulations, an analytic curve fit to these results is given which is accurate to within 3% of the emitted current.

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

NASA Astrophysics Data System (ADS)

Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

2016-07-01

Most recent works consider the occurrence of electrostatic discharges (ESD) on the surface of the spacecraft due to spacecraft charging as a consequence of its surface interaction with the surrounding space plasma and solar radiation [1]. At the same time, low-orbit spacecraft are simultaneously exposed to the hot magnetospheric plasma with the typical energies of the particles ~ 0.1 - 50 keV and to the particles of the Earth radiation belts (ERB) with a typical energy in the range of 0.1-10 MeV. Electrons of ERB with these energies penetrate into spacecraft dielectrics on the order of a few millimeters in depth and create an embedded charge with their own electric field. It has been shown in a number of papers that exactly a volume charge of the electrons of ERB can be the cause of ESD on spacecraft [2,3]. In this work we present the results of calculation of the dose rate and, correspondingly, the radiation conductivity in a typical spacecraft dielectrics, arising under the action of the hot magnetospheric plasma and electrons of ERB. Using software packages based on Monte Carlo methods and on the solution of equations of charge transport in spacecraft dielectrics, it is shown that in a number of areas of the Earth's magnetosphere the ESD can occur under the action of the ERB electrons. The results of present work can provide a basis for creation of the standard, characterizing the emergence of ESR on spacecraft due to volume charging of dielectrics and describing the methods of laboratory tests of spacecraft dielectrics. L.S. Novikov, A.A. Makletsov, and V.V. Sinolits, Comparison of Coulomb-2, NASCAP-2K, MUSCAT and SPIS codes for geosynchronous spacecraft charging, Advances in Space Research, 2016, V. 57, Is. 2, pp. 671-680. Wrenn G.L., Smith R.J.K. The ESD Threat to GEO Satellites: Empirical Models for Observed Effects Due to Both Surface and Internal Charging. Proc. ESA Symp. "Environment Modelling for Space-based Applications", ESTEC Noordwijk, The Netherlands, 1996, pp. 121-124. Paulmier, T., Dirassen, B., Arnaout, M., Payan, D., Balcon, N., Radiation-Induced Conductivity of Space Used Polymers Under High Energy Electron Irradiation, Plasma Science, IEEE Transactions, 2015, V. 43, No. 9, pp.2907-2914.

Effects of neutral gas releases on electron beam injection from electrically tethered spacecraft

NASA Technical Reports Server (NTRS)

Winglee, R. M.

1990-01-01

The presence of high neutral densities at low altitudes and/or during thruster firings is known to modify the spacecraft potential during active electron beam injection. Two-dimensional (three velocity) particle simulations are used to investigate the ionization processes including the neutral density required, the modification of the spacecraft potential, beam profile and spatial distribution of the return current into the spacecraft. Three processes are identified: (1) beam-induced ionization, (2) vehicle-induced ionization, and (3) beam plasma discharge. Only in the first two cases does the beam propagate away with little distortion.

Transiting Planets from Kepler, K2 & TESS

NASA Technical Reports Server (NTRS)

Lissauer, Jack

2018-01-01

NASA's Kepler spacecraft, launched in 2009, has been a resounding success. More than 4000 planet candidates have been identified using data from Kepler primary mission, which ended in 2013, and greater than 2000 of these candidates have been verified as bona fide exoplanets. After the loss of two reaction wheels ended the primary mission, the Kepler spacecraft was repurposed in 2014 to observe many fields on the sky for short periods. This new mission, dubbed K2, has led to the discovery of greater than 600 planet candidates, approximately 200 of which have been verified to date; most of these exoplanets are closer to us than the majority of exoplanets discovered by the primary Kepler mission. TESS, launching in 2018, will survey most of the sky for exoplanets, with emphasis on those orbiting nearby and/or bright host stars, making these planets especially well-suited for follow-up observations with other observatories to characterize atmospheric compositions and other properties. More than one-third of the planet candidates found by NASA's are associated with target stars that have more than one planet candidate, and such 'multis' account for the majority of candidates that have been verified as true planets. The large number of multis tells us that flat multiplanet systems like our Solar System are common. Virtually all of the candidate planetary systems are stable, as tested by numerical integrations that assume a physically motivated mass-radius relationship. Statistical studies performed on these candidate systems reveal a great deal about the architecture of planetary systems, including the typical spacing of orbits and flatness. The characteristics of several of the most interesting confirmed Kepler & K2 multi-planet systems will also be discussed.

Spacecraft Observations of Oblique Electron Beams Breaking the Frozen-In Law During Asymmetric Reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Egedal, J.; Le, Ari; Daughton, William

Fully kinetic simulations of asymmetric magnetic reconnection reveal the presence of magnetic-field-aligned beams of electrons flowing toward the topological magnetic x line. Within the ~ 6d e electron-diffusion region, the beams become oblique to the local magnetic field, providing a unique signature of the electron-diffusion region where the electron frozen-in law is broken. These numerical predictions are confirmed by in situ Magnetospheric Multiscale spacecraft observations during asymmetric reconnection at Earth’s dayside magnetopause.

Spacecraft Observations of Oblique Electron Beams Breaking the Frozen-In Law During Asymmetric Reconnection

DOE PAGES

Egedal, J.; Le, Ari; Daughton, William; ...

2018-01-29

Fully kinetic simulations of asymmetric magnetic reconnection reveal the presence of magnetic-field-aligned beams of electrons flowing toward the topological magnetic x line. Within the ~ 6d e electron-diffusion region, the beams become oblique to the local magnetic field, providing a unique signature of the electron-diffusion region where the electron frozen-in law is broken. These numerical predictions are confirmed by in situ Magnetospheric Multiscale spacecraft observations during asymmetric reconnection at Earth’s dayside magnetopause.

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.

JPL preferred parts list: Reliable electronic components

NASA Technical Reports Server (NTRS)

Covey, R. E.; Scott, W. R.; Hess, L. M.; Steffy, T. G.; Stott, F. R.

1982-01-01

The JPL Preferred Parts List was prepared to provide a basis for selection of electronic parts for JPL spacecraft programs. Supporting tests for the listed parts were designed to comply with specific spacecraft environmental requirements. The list tabulates the electronic, magnetic, and electromechanical parts applicable to all JPL electronic equipment wherein reliability is a major concern. The parts listed are revelant to equipment supplied by subcontractors as well as fabricated at the laboratory.

NASA's Technical Handbook for Avoiding On-Orbit ESD Anomalies Due to Internal Charging Effects

NASA Technical Reports Server (NTRS)

Whittlesey, Albert; Garrett, Henry B.

1996-01-01

This paper describes NASA-HDBK-4002, "Avoiding Problems Caused by Spacecraft On-Orbit Internal Charging Effects". The handbook includes a description of internal charging and why it is of concern to spacecraft designers. It also suggests how to determine when a project needs to consider internal spacecraft charging, it contains an electron penetration depth chart, rationale for a critical electron flux criterion, a worst-case geosynchronous electron plasma spectrum, general design guidelines, quantitative design guidelines, and a typical materials characteristics list. Appendices include a listing of some environment codes, electron transport codes, a discussion of geostationary electron plasma environments, a brief description of electron beam and other materials tests, and transient susceptibility tests. The handbook will be in the web page, hftp://standards.nasa.gov. A prior document, NASA TP2361 "Design Guidelines for Assessing and controlling Spacecraft Charging Effects", 1984, is in use to describe mitigation techniques for the effects of surface charging of satellites in space plasma environments. HDBK-4002 is meant to complement 2361 and together, the pair of documents describe both cause and mitigation designs for problems caused by energetic space plasmas.

Modeling of spacecraft charging

NASA Technical Reports Server (NTRS)

Whipple, E. C., Jr.

1977-01-01

Three types of modeling of spacecraft charging are discussed: statistical models, parametric models, and physical models. Local time dependence of circuit upset for DoD and communication satellites, and electron current to a sphere with an assumed Debye potential distribution are presented. Four regions were involved in spacecraft charging: (1) undisturbed plasma, (2) plasma sheath region, (3) spacecraft surface, and (4) spacecraft equivalent circuit.

Spacecraft charging and ion wake formation in the near-Sun environment

NASA Astrophysics Data System (ADS)

Ergun, R. E.; Malaspina, D. M.; Bale, S. D.; McFadden, J. P.; Larson, D. E.; Mozer, F. S.; Meyer-Vernet, N.; Maksimovic, M.; Kellogg, P. J.; Wygant, J. R.

2010-07-01

A three-dimensional, self-consistent code is employed to solve for the static potential structure surrounding a spacecraft in a high photoelectron environment. The numerical solutions show that, under certain conditions, a spacecraft can take on a negative potential in spite of strong photoelectron currents. The negative potential is due to an electrostatic barrier near the surface of the spacecraft that can reflect a large fraction of the photoelectron flux back to the spacecraft. This electrostatic barrier forms if (1) the photoelectron density at the surface of the spacecraft greatly exceeds the ambient plasma density, (2) the spacecraft size is significantly larger than local Debye length of the photoelectrons, and (3) the thermal electron energy is much larger than the characteristic energy of the escaping photoelectrons. All of these conditions are present near the Sun. The numerical solutions also show that the spacecraft's negative potential can be amplified by an ion wake. The negative potential of the ion wake prevents secondary electrons from escaping the part of spacecraft in contact with the wake. These findings may be important for future spacecraft missions that go nearer to the Sun, such as Solar Orbiter and Solar Probe Plus.

Materials and techniques for spacecraft static charge control

NASA Technical Reports Server (NTRS)

Amore, L. J.; Eagles, A. E.

1977-01-01

An overview of the design, development, fabrication, and testing of transparent conductive coatings and conductive lattices deposited or formed on high resistivity spacecraft dielectric materials to obtain control static charge buildup on spacecraft external surfaces is presented. Fabrication techniques for the deposition of indium/tin oxide coatings and copper grid networks on Kapton and FEP Teflon films and special frit coatings for OSR and solar cell cover glasses are discussed. The techniques include sputtering, photoetching, silkscreening, and mechanical processes. A facility designed and built to simulate the electron plasma at geosynchronous altitudes is described along with test procedures. The results of material characterizations as well as electron irradiation aging effects in this facility for spacecraft polymers treated to control static charge are presented. The data presents results for electron beam energies up to 30 kV and electron current densities of 30 nA/cm squared. Parameters measured include secondary emission, surface leakage, and through the sample currents as a function of primary beam energy and voltage.

Finding False Positives Planet Candidates Due To Background Eclipsing Binaries in K2

NASA Astrophysics Data System (ADS)

Mullally, Fergal; Thompson, Susan E.; Coughlin, Jeffrey; DAVE Team

2016-06-01

We adapt the difference image centroid approach, used for finding background eclipsing binaries, to vet K2 planet candidates. Difference image centroids were used with great success to vet planet candidates in the original Kepler mission, where the source of a transit could be identified by subtracting images of out-of-transit cadences from in-transit cadences. To account for K2's roll pattern, we reconstruct out-of-transit images from cadences that are nearby in both time and spacecraft roll angle. We describe the method and discuss some K2 planet candidates which this method suggests are false positives.

Spacecraft Charging Standard Report.

DTIC Science & Technology

1980-09-30

SSPM include: SAMPLE POTENTIAL (with respect to S/C ground) Aluminized Kapton -2.0 kV Silvered Teflon -4.0 kV Astroquartz -3.7 kV 50.3 Analysis. As...and potential gradients on the space vehicle (candidate spacecraft locations for ESD tests) (The NASCAP computer code, when validated, will be useful...The coupling analysis should then determine as a minimum: I. electromagnetic fields generated interior to the space vehicle due to ESD 2. induced

Diffusion Region's Structure at the Subsolar Magnetopause with MMS Data

NASA Astrophysics Data System (ADS)

Cozzani, G.; Retino, A.; Califano, F.; Alexandrova, A.; Catapano, F.; Fu, H.; Le Contel, O.; Khotyaintsev, Y. V.; Vaivads, A.; Ahmadi, N.; Lindqvist, P. A.; Breuillard, H.; Mirioni, L.; Ergun, R.; Torbert, R. B.; Giles, B. L.; Russell, C. T.; Nakamura, R.; Moore, T. E.; Fuselier, S. A.; Mauk, B.; Burch, J.

2017-12-01

Magnetic reconnection occurs in the magnetosphere in thin current sheets, where a change in the magneticfield topology leads to rapid conversion of magnetic energy into ion and electron energy. To allow for magneticfield reconfiguration, both ions and electrons have to become demagnetized in the ion and electron diffusionregions, respectively. MMS spacecraft observations at inter-spacecraft separation ˜ 10 km (correspondingto ˜ 5 d_e at the magnetopause) allow, for the first time, to make multi-point studies of the structure of theelectron diffusion region (EDR). We present MMS observations on January,27th 2017 of one magnetopausecrossing close to the subsolar point showing several signatures consistent with an EDR encounter nearbya magnetic field minimum. The proximity to the reconnection site is further substantiated by the FirstOrder Taylor Expansion (FOTE) method applied to the magnetic field data. Observations suggest that allspacecraft passed through the EDR. Despite of the small inter-spacecraft separation (7 km), the observationsshow important differences among spacecraft. We focus on the comparison between MMS3 and MMS4 sincethey show the most striking differences. MMS3 measures a stronger parallel electron heating and highercurrent densities than MMS4. Both satellites observe crescent-shaped electron distribution functions on themagnetospheric side but MMS4 observes them over a longer time interval. These observations suggest thatMMS3 is passing closer to the reconnection site than MMS4. The differences between the observations by thetwo spacecraft indicate that the EDR is rather structured over scales of a few electron inertial lengths. Wealso evaluate the Generalized Ohm's law and find that the electric field is mainly balanced by the divergenceof the electron pressure tensor while the electron inertia term is negligible.

Comets - Groundbased observations of spacecraft mission candidates

NASA Technical Reports Server (NTRS)

Osip, David J.; Schleicher, David G.; Millis, Robert L.

1992-01-01

Ground-based narrowband photometry results are presented for nine candidate comets for flyby and/or rendezvous missions. The comets include Churyumov-Gerasimenko, d'Arrest, Encke, Grigg-Skjellerup, Honda-Mrkos-Pajdusakova, Kopff, Tempel 1, Tempel 2, and Wild 2. On the basis of measured OH production rates and a model of the sublimation of water from the surface, limits are derived on the size of each cometary nucleus. A detailed analysis of the characteristics of these nine viable mission candidates can furnish the bases for the prioritization of targets of prospective missions.

Replacement of ozone depleting and toxic chemicals in gravimetric analysis of non-volatile residue

NASA Technical Reports Server (NTRS)

Arnold, G. S.; Uht, J. C.; Sinsheimer, F. B.

1995-01-01

The standard tests for determining nonvolatile residue accretion on spacecraft surfaces and in clean processing facilities rely on the use of halogenated solvents that are targeted for elimination because of their toxic or ozone-depleting natures. This paper presents a literature-based screening survey for candidate replacement solvents. Potential replacements were evaluated for their vapor pressure, toxicity, and solvent properties. Three likely candidates were identified: ethyl acetate, methyl acetate, and acetone. Laboratory tests are presented that evaluate the suitability of these candidate replacement solvents.

Wavefront tilt feedforward for the formation interferometer testbad (FIT)

NASA Technical Reports Server (NTRS)

Shields, J. F.; Liewer, K.; Wehmeier, U.

2002-01-01

Separated spacecraft interferometry is a candidate architecture for several future NASA missions. The Formation Interferometer Testbed (FIT) is a ground based testbed dedicated to the validation of this key technology for a formation of two spacecraft. In separated spacecraft interferometry, the residual relative motion of the component spacecraft must be compensated for by articulation of the optical components. In this paper, the design of the FIT interferometer pointing control system is described. This control system is composed of a metrology pointing loop that maintains an optical link between the two spacecraft and two stellar pointing loops for stabilizing the stellar wavefront at both the right and left apertures of the instrument. A novel feedforward algorithm is used to decouple the metrology loop from the left side stellar loop. Experimental results from the testbed are presented that verify this approach and that fully demonstrate the performance of the algorithm.

Development of a 3D numerical code to calculate the trajectories of the blow off electrons emitted by a vacuum surface discharge: Application to the study of the electromagnetic interference induced on a spacecraft

NASA Astrophysics Data System (ADS)

Froger, Etienne

1993-05-01

A description of the electromagnetic behavior of a satellite subjected to an electric discharge is given using a specially developed numerical code. One of the particularities of vacuum discharges, obtained by irradiation of polymers, is the intense emission of electrons into the spacecraft environment. Electromagnetic radiation, associated with the trajectories of the particles around the spacecraft, is considered as the main source of the interference observed. In the absence of accurate orbital data and realistic ground tests, the assessment of these effects requires numerical simulation of the interaction between this electron source and the spacecraft. This is done by the GEODE particle code which is applied to characteristic configurations in order to estimate the spacecraft response to a discharge, which is simulated from a vacuum discharge model designed in laboratory. The spacecraft response to a current injection is simulated by the ALICE numerical three dimensional code. The comparison between discharge and injection effects, from the results given by the two codes, illustrates the representativity of electromagnetic susceptibility tests and the main parameters for their definition.

Universal Controller for Spacecraft Mechanisms

NASA Technical Reports Server (NTRS)

Levanas, Greg; McCarthy, Thomas; Hunter, Don; Buchanan, Christine; Johnson, Michael; Cozy, Raymond; Morgan, Albert; Tran, Hung

2006-01-01

An electronic control unit has been fabricated and tested that can be replicated as a universal interface between the electronic infrastructure of a spacecraft and a brushless-motor (or other electromechanical actuator) driven mechanism that performs a specific mechanical function within the overall spacecraft system. The unit includes interfaces to a variety of spacecraft sensors, power outputs, and has selectable actuator control parameters making the assembly a mechanism controller. Several control topologies are selectable and reconfigurable at any time. This allows the same actuator to perform different functions during the mission life of the spacecraft. The unit includes complementary metal oxide/semiconductor electronic components on a circuit board of a type called rigid flex (signifying flexible printed wiring along with a rigid substrate). The rigid flex board is folded to make the unit fit into a housing on the back of a motor. The assembly has redundant critical interfaces, allowing the controller to perform time-critical operations when no human interface with the hardware is possible. The controller is designed to function over a wide temperature range without the need for thermal control, including withstanding significant thermal cycling, making it usable in nearly all environments that spacecraft or landers will endure. A prototype has withstood 1,500 thermal cycles between 120 and +85 C without significant deterioration of its packaging or electronic function. Because there is no need for thermal control and the unit is addressed through a serial bus interface, the cabling and other system hardware are substantially reduced in quantity and complexity, with corresponding reductions in overall spacecraft mass and cost.

Microscopic Electron Variations Measured Simultaneously By The Cluster Spacecraft

NASA Astrophysics Data System (ADS)

Buckley, A. M.; Carozzi, T. D.; Gough, M. P.; Beloff, N.

Data is used from the Particle Correlator experiments running on each of the four Cluster spacecraft so as to determine common microscopic behaviour in the elec- tron population observed over the macroscopic Cluster separations. The Cluster par- ticle correlator experiments operate by forming on board Auto Correlation Functions (ACFs) generated from short time series of electron counts obtained, as a function of electron energy, from the PEACE HEEA sensor. The information on the microscopic variation of the electron flux covers the frequency range DC up to 41 kHz (encom- passing typical electron plasma frequencies and electron gyro frequencies and their harmonics), the electron energy range is that covered by the PEACE HEEA sensor (within the range 1 eV to 26 keV). Results are presented of coherent electron struc- tures observed simultaneously by the four spacecraft in the differing plasma interac- tion regions and boundaries encountered by Cluster. As an aid to understanding the plasma interactions, use is made of numerical simulations which model both the un- derlying statistical properties of the electrons and also the manner in which particle correlator experiments operate.

Spacecraft Charging Technology, 1978

NASA Technical Reports Server (NTRS)

1979-01-01

The interaction of the aerospace environment with spacecraft surfaces and onboard, high voltage spacecraft systems operating over a wide range of altitudes from low Earth orbit to geosynchronous orbit is considered. Emphasis is placed on control of spacecraft electric potential. Electron and ion beams, plasma neutralizers material selection, and magnetic shielding are among the topics discussed.

Panoramic attitude sensor for Radio Astronomy Explorer B

NASA Technical Reports Server (NTRS)

Thomsen, R.

1973-01-01

An instrument system to acquire attitude determination data for the RAE-B spacecraft was designed and built. The system consists of an electronics module and two optical scanner heads. Each scanner head has an optical scanner with a field of view of 0.7 degrees diameter which scans the sky and measures the position of the moon, earth and sun relative to the spacecraft. This scanning is accomplished in either of two modes. When the spacecraft is spinning, the scanner operates in spherical mode, with the spacecraft spin providing the slow sweep of lattitude to scan the entire sky. After the spacecraft is placed in lunar orbit and despun, the scanner will operate in planar mode, advancing at a rate of 5.12 seconds per revolution in a fixed plane parallel to the spacecraft Z axis. This scan will cross and measure the moon horizons with every revolution. Each scanner head also has a sun slit which is aligned parallel to the spin axis of the spacecraft and which provides a sun pulse each revolution of the spacecraft. The electronics module provides the command and control, data processing and housekeeping functions.

Space storable propellant acquisition system

NASA Technical Reports Server (NTRS)

Tegart, J. R.; Uney, P. E.; Anderson, J. E.; Fester, D. A.

1972-01-01

Surface tension propellant acquisition concepts for an advanced spacecraft propulsion system having a 10-year mission capability were investigated. Surface tension systems were specified because they were shown to be the best propellant acquisition technique for various interplanetery spacecraft in a prior study. A variety of surface tension concepts for accomplishing propellant acquisition were formulated for the baseline space storable propulsion module and Jupiter Orbiter mission. Analyses and evaluations were then conducted on each candidate concept to assess fabricability, performance capability, and spacecraft compatibility. A comparative evaluation of the results showed the Fruhof-class of low-g surface tension systems to be preferred for these interplanetary applications.

Interplanetary spacecraft design using solar electric propulsion

NASA Technical Reports Server (NTRS)

Duxbury, J. H.; Paul, G. M.

1974-01-01

Emphasis of the electric propulsion technology program is now on the application of solar electric propulsion to scientific missions. Candidate planetary, cometary, and geosynchronous missions are being studied. The object of this paper is to describe a basic spacecraft design proposed as the means to accomplish (1) a comet Encke slow flyby, (2) a comet Encke rendezvous, and (3) an out-of-the-ecliptic mission. The discussion includes design differences foreseen for the various missions and indicates those areas where spacecraft design commonality is possible. Particular emphasis is placed on a solar electric propulsion module design which permits an attractive degree of design inheritance from mission to mission.

Spacecraft-charging mitigation of a high-power electron beam emitted by a magnetospheric spacecraft: Simple theoretical model for the transient of the spacecraft potential

DOE PAGES

Castello, Federico Lucco; Delzanno, Gian Luca; Borovsky, Joseph E.; ...

2018-05-29

A spacecraft-charging mitigation scheme necessary for the operation of a high-power electron beam in the low-density magnetosphere is analyzed. The scheme is based on a plasma contactor, i.e. a high-density charge-neutral plasma emitted prior to and during beam emission, and its ability to emit high ion currents without strong space-charge limitations. A simple theoretical model for the transient of the spacecraft potential and contactor expansion during beam emission is presented. The model focuses on the contactor ion dynamics and is valid in the limit when the ion contactor current is equal to the beam current. The model is found inmore » very good agreement with Particle-In-Cell simulations over a large parametric study that varies the initial expansion time of the contactor, the contactor current and the ion mass. The model highlights the physics of the spacecraft-charging mitigation scheme, indicating that the most important part of the dynamics is the evolution of the outermost ion front which is pushed away by the charge accumulated in the system by the beam. The model can be also used to estimate the long-time evolution of the spacecraft potential. For a short contactor expansion (0.3 or 0.6 ms Helium plasma or 0.8 ms Argon plasma, both with 1 mA current) it yields a peak spacecraft potential of the order of 1-3 kV. This implies that a 1-mA relativistic electron beam would be easily emitted by the spacecraft.« less

Spacecraft-charging mitigation of a high-power electron beam emitted by a magnetospheric spacecraft: Simple theoretical model for the transient of the spacecraft potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castello, Federico Lucco; Delzanno, Gian Luca; Borovsky, Joseph E.

A spacecraft-charging mitigation scheme necessary for the operation of a high-power electron beam in the low-density magnetosphere is analyzed. The scheme is based on a plasma contactor, i.e. a high-density charge-neutral plasma emitted prior to and during beam emission, and its ability to emit high ion currents without strong space-charge limitations. A simple theoretical model for the transient of the spacecraft potential and contactor expansion during beam emission is presented. The model focuses on the contactor ion dynamics and is valid in the limit when the ion contactor current is equal to the beam current. The model is found inmore » very good agreement with Particle-In-Cell simulations over a large parametric study that varies the initial expansion time of the contactor, the contactor current and the ion mass. The model highlights the physics of the spacecraft-charging mitigation scheme, indicating that the most important part of the dynamics is the evolution of the outermost ion front which is pushed away by the charge accumulated in the system by the beam. The model can be also used to estimate the long-time evolution of the spacecraft potential. For a short contactor expansion (0.3 or 0.6 ms Helium plasma or 0.8 ms Argon plasma, both with 1 mA current) it yields a peak spacecraft potential of the order of 1-3 kV. This implies that a 1-mA relativistic electron beam would be easily emitted by the spacecraft.« less

Confidence Level Based Approach to Total Dose Specification for Spacecraft Electronics

NASA Technical Reports Server (NTRS)

Xapsos, M. A.; Stauffer, C.; Phan, A.; McClure, S. S.; Ladbury, R. L.; Pellish, J. A.; Campola, M. J.; Label, K. A.

2017-01-01

A confidence level based approach to total dose radiation hardness assurance is presented for spacecraft electronics. It is applicable to both ionizing and displacement damage dose. Results are compared to the traditional approach that uses radiation design margin and advantages of the new approach are discussed.

New Approach to Total Dose Specification for Spacecraft Electronics

NASA Technical Reports Server (NTRS)

Xapsos, Michael

2017-01-01

Variability of the space radiation environment is investigated with regard to total dose specification for spacecraft electronics. It is shown to have a significant impact. A new approach is developed for total dose requirements that replaces the radiation design margin concept with failure probability during a mission.

Spacecraft Environments Interactive: Space Radiation and Its Effects on Electronic System

NASA Technical Reports Server (NTRS)

Howard, J. W., Jr.; Hardage, D. M.

1999-01-01

The natural space environment is characterized by complex and subtle phenomena hostile to spacecraft. Effects of these phenomena impact spacecraft design, development, and operation. Space systems become increasingly susceptible to the space environment as use of composite materials and smaller, faster electronics increases. This trend makes an understanding of space radiation and its effects on electronic systems essential to accomplish overall mission objectives, especially in the current climate of smaller/better/cheaper faster. This primer outlines the radiation environments encountered in space, discusses regions and types of radiation, applies the information to effects that these environments have on electronic systems, addresses design guidelines and system reliability, and stresses the importance of early involvement of radiation specialists in mission planning, system design, and design review (part-by-part verification).

The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket, first flight

NASA Astrophysics Data System (ADS)

Christe, Steven; Glesener, L.; Ishikawa, S.; Ramsey, B.; Takahashi, T.; Watanabe, S.; Saito, S.; Lin, R. P.; Krucker, S.

2013-07-01

Understanding electron acceleration in solar flares requires X-ray studies with greater sensitivity and dynamic range than are available with current solar hard X-ray observers (i.e. the RHESSI spacecraft). RHESSI employs an indirect Fourier imaging method that is intrinsically limited in dynamic range and therefore can rarely image faint coronal flare sources in the presence of bright footpoints. With greater sensitivity and dynamic range, electron acceleration sites in the corona could be studied in great detail. Both these capabilities can be advanced by the use of direct focusing optics. The recently flown Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload demonstrates the feasibility and usefulness of hard X-ray focusing optics for observations of solar hard X-rays. FOXSI features grazing-incidence replicated nickel optics made by the NASA Marshall Space Flight Center and fine-pitch silicon strip detectors developed by the Astro-H team at JAXA/ISAS. FOXSI flew successfully on November 2, 2012, producing images and spectra of a microflare and performing a search for nonthermal emission (4-15 keV) from nanoflares in the quiet Sun. Nanoflares are a candidate for providing the required energy to heat the solar corona to its high temperature of a few million degrees. A future satellite version of FOXSI, featuring similar optics and detectors, could make detailed observations of hard X-rays from flare-accelerated electrons, identifying and characterizing particle acceleration sites and mapping out paths of energetic electrons as they leave these sites and propagate throughout the solar corona.Abstract (2,250 Maximum Characters): Understanding electron acceleration in solar flares requires X-ray studies with greater sensitivity and dynamic range than are available with current solar hard X-ray observers (i.e. the RHESSI spacecraft). RHESSI employs an indirect Fourier imaging method that is intrinsically limited in dynamic range and therefore can rarely image faint coronal flare sources in the presence of bright footpoints. With greater sensitivity and dynamic range, electron acceleration sites in the corona could be studied in great detail. Both these capabilities can be advanced by the use of direct focusing optics. The recently flown Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload demonstrates the feasibility and usefulness of hard X-ray focusing optics for observations of solar hard X-rays. FOXSI features grazing-incidence replicated nickel optics made by the NASA Marshall Space Flight Center and fine-pitch silicon strip detectors developed by the Astro-H team at JAXA/ISAS. FOXSI flew successfully on November 2, 2012, producing images and spectra of a microflare and performing a search for nonthermal emission (4-15 keV) from nanoflares in the quiet Sun. Nanoflares are a candidate for providing the required energy to heat the solar corona to its high temperature of a few million degrees. A future satellite version of FOXSI, featuring similar optics and detectors, could make detailed observations of hard X-rays from flare-accelerated electrons, identifying and characterizing particle acceleration sites and mapping out paths of energetic electrons as they leave these sites and propagate throughout the solar corona.

Atomic Oxygen Exposure of Power System and other Spacecraft Materials: Results of the EOIM-3 Experiment

NASA Technical Reports Server (NTRS)

Morton, Thomas L.; Ferguson, Dale C.

1997-01-01

In order to test their reactivity with Atomic Oxygen, twenty five materials were flown on the EOIM-3 (Evaluation of Oxygen Interactions with Materials) portion of the STS-46 Mission. These materials include refractory metals, candidate insulation materials, candidate radiator coatings, and a selection of miscellaneous materials. This report documents the results of the pre- and post-flight analysis of these materials.

Looking for Ice

NASA Image and Video Library

2016-03-23

This image was targeted for NASA Mars Reconnaissance Orbiter spacecraft to look at a candidate new crater on a lobate apron. Such aprons are often ice-rich, but the crater shows no bright material that would indicate ice.

Experiments On Transparent Conductive Films For Spacecraft

NASA Technical Reports Server (NTRS)

Perez-Davis, Marla E.; Rutledge, Sharon K.; De Groh, Kim K.; Hung, Ching-Cheh; Malave-Sanabria, Tania; Hambourger, Paul; Roig, David

1995-01-01

Report describes experiments on thin, transparent, electrically conductive films made, variously, of indium tin oxide covered by magnesium fluoride (ITO/MgF2), aluminum-doped zinc oxide (AZO), or pure zinc oxide (ZnO). Films are candidates for application to such spacecraft components, including various optoelectronic devices and window surfaces that must be protected against buildup of static electric charge. On Earth, such films useful on heat mirrors, optoelectronic devices, gas sensors, and automotive and aircraft windows.

Small-Scale Dayside Magnetic Reconnection Analysis via MMS

NASA Astrophysics Data System (ADS)

Pritchard, K. R.; Burch, J. L.; Fuselier, S. A.; Webster, J.; Genestreti, K.; Torbert, R. B.; Rager, A. C.; Phan, T.; Argall, M. R.; Le Contel, O.; Russell, C. T.; Strangeway, R. J.; Giles, B. L.

2017-12-01

The Magnetospheric Multiscale (MMS) mission has the primary objective of understanding the physics of the reconnection electron diffusion region (EDR), where magnetic energy is transformed into particle energy. In this poster, we present data from an EDR encounter that occurred in late December 2016 at approximately 11:00 MLT with a moderate guide field. The spacecraft were in a tetrahedral formation with an average inter-spacecraft distance of approximately 7 kilometers. During this event electron crescent-shaped distributions were observed in the electron stagnation region as is typical for asymmetric reconnection. Based on the observed ion velocity jets, the spacecraft traveled just south of the EDR. Because of the close spacecraft separation, fairly accurate computation of the Hall, electron pressure divergence, and electron inertia components of the reconnection electric field could be made. In the region of the crescent distributions good agreement was observed, with the strongest component being the normal electric field and the most significant sources being electron pressure divergence and the Hall electric field. While the strongest currents were in the out-of-plane direction, the dissipation was strongest in the normal direction because of the larger magnitude of the normal electric field component. These results are discussed in light of recent 3D PIC simulations performed by other groups.

Ion composition and upstream solar wind observations at comet Giacobini-Zinner

NASA Astrophysics Data System (ADS)

Coplan, M. A.; Ogilvie, K. W.; A'Hearn, M. F.; Bochsler, P.; Geiss, J.

1987-01-01

The observations by the ion composition instrument (ICI) on the ICE spacecraft made during the encounter with comet P/Giacobini-Zinner (Ogilvie et al., 1986) are discussed in detail. Solar wind He-4(2+) kinetic temperatures, densities, and velocities before, during, and after the encounter are presented. These data combined with He-4(2+) velocity distributions provide evidence for the existence of a thick diffuse shock. Relative abundances of water group ions and CO(+) are derived along with an estimate of the abundance of an ion with M/Q = 24 + or - 1 amu/e. The ICI data are compared with electron data from two other experiments (Bame et al., 1986; Meyer-Vernet et al., 1986) and found to be in reasonable agreement in the region outside the tail. Spectroscopic data for several neutral and ionic species are compared with the ICI results for the water group ions and CO(+). The spectroscopic data are also used to eliminate Mg(+) and CN(+) as candidates for the M/Q = 24 peak. The two most likely candidates are C2(+) and Na(+), but neither photoionization of parent neutrals nor sputtering from dust grains is sufficient to explain the observed abundance relative to H2O(+).

Bounding Extreme Spacecraft Charging in the Lunar Environment

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Parker, Linda N.

2008-01-01

Robotic and manned spacecraft from the Apollo era demonstrated that the lunar surface in daylight will charge to positive potentials of a few tens of volts because the photoelectron current dominates the charging process. In contrast, potentials of the lunar surface in darkness which were predicted to be on the order of a hundred volts negative in the Apollo era have been shown more recently to reach values of a few hundred volts negative with extremes on the order of a few kilovolts. The recent measurements of night time lunar surface potentials are based on electron beams in the Lunar Prospector Electron Reflectometer data sets interpreted as evidence for secondary electrons generated on the lunar surface accelerated through a plasma sheath from a negatively charged lunar surface. The spacecraft potential was not evaluated in these observations and therefore represents a lower limit to the magnitude of the lunar negative surface potential. This paper will describe a method for obtaining bounds on the magnitude of lunar surface potentials from spacecraft measurements in low lunar orbit based on estimates of the spacecraft potential. We first use Nascap-2k surface charging analyses to evaluate potentials of spacecraft in low lunar orbit and then include the potential drops between the ambient space environment and the spacecraft to the potential drop between the lunar surface and the ambient space environment to estimate the lunar surface potential from the satellite measurements.

DMSP Spacecraft Charging in Auroral Environments

NASA Technical Reports Server (NTRS)

Colson, Andrew; Minow, Joseph

2011-01-01

The Defense Meteorological Satellite Program (DMSP) spacecraft are a series of low-earth orbit (LEO) satellites whose mission is to observe the space environment using the precipitating energetic particle spectrometer (SSJ/4-5). DMSP satellites fly in a geosynchronous orbit at approx.840 km altitude which passes through Earth s ionosphere. The ionosphere is a region of partially ionized gas (plasma) formed by the photoionization of neutral atoms and molecules in the upper atmosphere of Earth. For satellites in LEO, such as DMSP, the plasma density is usually high and the main contributors to the currents to the spacecraft are the precipitating auroral electrons and ions from the magnetosphere as well as the cold plasma that constitutes the ionosphere. It is important to understand how the ionosphere and auroral electrons can accumulate surface charges on satellites because spacecraft charging has been the cause of a number of significant anomalies for on-board instrumentation on high altitude spacecraft. These range from limiting the sensitivity of measurements to instrument malfunction depending on the magnitude of the potential difference over the spacecraft surface. Interactive Data Language (IDL) software was developed to process SSJ/4-5 electron and ion data and to create a spectrogram of the particles number and energy fluxes. The purpose of this study is to identify DMSP spacecraft charging events and to present a preliminary statistical analysis. Nomenclature

A background correction algorithm for Van Allen Probes MagEIS electron flux measurements

DOE PAGES

Claudepierre, S. G.; O'Brien, T. P.; Blake, J. B.; ...

2015-07-14

We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) electron flux measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS electron data: inner zone protons and bremsstrahlung X-rays generated by energetic electrons interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS electron channels (~30–500 keV) and in regions of geospace where multi-M eV electrons are present. Inner zone protons produce contamination in all MagEIS energymore » channels at roughly L < 2.5. The background-corrected MagEIS electron data produce a more accurate measurement of the electron radiation belts, as most earlier measurements suffer from unquantifiable and uncorrectable contamination in this harsh region of the near-Earth space environment. These background-corrected data will also be useful for spacecraft engineering purposes, providing ground truth for the near-Earth electron environment and informing the next generation of spacecraft design models (e.g., AE9).« less

High voltage cabling for high power spacecraft

NASA Technical Reports Server (NTRS)

Dunbar, W. G.

1981-01-01

Studies by NASA have shown that many of the space missions proposed for the time period 1980 to 2000 will require large spacecraft structures to be assembled in orbit. Large antennas and power systems up to 2.5 MW size are predicted to supply the electrical/electronic subsystems, solar electric subsystems, solar electric propulsion, and space processing for the near-term programs. Platforms of 100 meters/length for stable foundations, utility stations, and supports for these multi-antenna and electronic powered mechanisms are also being considered. This paper includes the findings of an analytic and conceptual design study for large spacecraft power distribution, and electrical loads and their influence on the cable and connector requirements for these proposed large spacecraft.

Secondary Electron Emission From Solar Cell Coverslides And Its Effect On Absolute Vehicle Charging

NASA Astrophysics Data System (ADS)

Ferguson, Dale C.

2011-10-01

It has often been stated that earthed conductive solar cell coverslides are the best way to prevent electrostatic discharges on space solar arrays in GEO. While it is true that such coverslides will prevent differential charging on the solar arrays, it will be shown through NASCAP- 2k simulations that the secondary electron emission of such coverslides is very important for absolute vehicle charging. In particular, carbon nanotube coatings, due to the extremely low secondary electron emission from carbon, may exacerbate absolute vehicle charging. However, if they are earthed, because of their conductivity they may minimize differential charging and the possibility of arcing elsewhere on the spacecraft. Such results may also be true for insulative coverslides if spacecraft thermal blankets are made of materials with high secondary electron emission. Finally, photoemission from coverslides is investigated, with regard to anti-reflection coatings. Surfaces which reflect UV can have low photoemission, while those that absorb may have higher photoemission rates. Thus, anti-reflection coatings may lead to higher absolute spacecraft charging rates. NASCAP-2k simulations will be used to investigate these dependences for realistic spacecraft.

Correcting PSP electron measurements for the effects of spacecraft electrostatic and magnetic fields

NASA Astrophysics Data System (ADS)

McGinnis, D.; Halekas, J. S.; Larson, D. E.; Whittlesey, P. L.; Kasper, J. C.

2017-12-01

The near-Sun environment which the Parker Solar Probe will investigate presents a unique challenge for the measurement of thermal and suprathermal electrons. Over one orbital period, the ionizing photon flux and charged particle densities vary to such an extent that the spacecraft could charge to electrostatic potentials ranging from a few volts to tens of volts or more, and it may even develop negative electrostatic potentials near closest approach. In addition, significant permanent magnetic fields from spacecraft components will perturb thermal electron trajectories. Given these effects, electron distribution function (EDF) measurements made by the SWEAP/SPAN electron sensors will be significantly affected. It is thus important to try to understand the extent and nature of such effects, and to remediate them as much as possible. To this end, we have incorporated magnetic fields and a model electrostatic potential field into particle tracing simulations to predict particle trajectories through the near spacecraft environment. These simulations allow us to estimate how the solid angle elements measured by SPAN deflect and stretch in the presence of these fields and therefore how and to what extent EDF measurements will be distorted. In this work, we demonstrate how this technique can be used to produce a `dewarping' correction factor. Further, we show that this factor can correct synthetic datasets simulating the warped EDFs that the SPAN instruments are likely to measure over a wide range of spacecraft potentials and plasma Debye lengths.

Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection

NASA Technical Reports Server (NTRS)

Egedal, J.; Le, A.; Daughton, W.; Wetherton, B.; Cassak, P.A.; Chen, L.-J.; Lavraud, B.; Trobert, Roy; Dorelli, J.; Gershman, D. J.;

Plasma electron analysis: Voyager plasma science experiment

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.

1983-01-01

The Plasma Science Experiment (PLS) on the Voyager spacecraft provide data on the plasma ions and electrons in the interplanetary medium and the magnetospheres of the giant planets Jupiter and Saturn. A description of the analysis used to obtain electron parameters (density, temperature, etc.) from the plasma science experiment PLS electron measurements which cover the energy range from 10 eV to 5950 eV is presented. The electron sensor (D cup) and its transmission characteristics are described. A derivation of the fundamental analytical expression of the reduced distribution function F(e) is given. The electron distribution function F(e), used in the moment integrations, can be derived from F(e). Positive ions produce a correction current (ion feedthrough) to the measured electron current, which can be important to the measurements of the suprathermal electron component. In the case of Saturn, this correction current, which can either add to or subtract from the measured electron current, is less than 20% of the measured signal at all times. Comments about the corrections introduced by spacecraft charging to the Saturn encounter data, which can be important in regions of high density and shadow when the spacecraft can become negatively charged are introduced.

Impact ionization study

NASA Technical Reports Server (NTRS)

Whipple, E. C., Jr.

1982-01-01

The impact ionization phenomenon which was observed on certain spacecraft was studied. The phenomenon occurs when a neutral atom, molecule, or ion strikes a surface with sufficient kinetic energy that either the incident neutral or atoms on the surface are ionized, with subsequent escape of ions and/or electrons. The released ions and electrons can interfere with measurements on the spacecraft by confusing interpretation of the data. On the other hand, there is the possibility that the effect could be developed into a diagnostic tool for investigating neutral atmospheric species or for studying physical processes on spacecraft surfaces.

Science aspects of a 1980 flyby of Comet Encke with a Pioneer spacecraft

NASA Technical Reports Server (NTRS)

Jaffe, L. D.; Elachi, C.; Giffin, C. E.; Huntress, W.; Newburn, R. L.; Parker, R. H.; Taylor, F. W.; Thorpe, T. E.

1974-01-01

Results are presented of an investigation of the feasibility of a 1980 flyby of Comet Encke using a Pioneer class spacecraft. Specific areas studied include: science objectives and rationale; science observables; effects of encounter velocity; science encounter and targeting requirements; selection and description of science instruments; definition of a candidate science payload; engineering characteristics of suggested payload; value of a separable probe; science instruments for a separable probe; science payload integration problems; and science operations profile.

Voyager 2 Neptune targeting strategy

NASA Technical Reports Server (NTRS)

Potts, C. L.; Francis, K.; Matousek, S. E.; Cesarone, R. J.; Gray, D. L.

1989-01-01

The success of the Voyager 2 flybys of Neptune and Triton depends upon the ability to correct the spacecraft's trajectory. Accurate spacecraft delivery to the desired encounter conditions will promote the maximum science return. However, Neptune's great distance causes large a priori uncertainties in Neptune and Triton ephemerides and planetary system parameters. Consequently, the 'ideal' trajectory is unknown beforehand. The targeting challenge is to utilize the gradually improving knowledge as the spacecraft approaches Neptune to meet the science objectives, but with an overriding concern for spacecraft safety and a desire to limit propellant expenditure. A unique targeting strategy has been developed in response to this challenge. Through the use of a Monte Carlo simulation, candidate strategies are evaluated by the degree to which they meet these objectives and are compared against each other in determining the targeting strategy to be adopted.

Mission operations for unmanned nuclear electric propulsion outer planet exploration with a thermionic reactor spacecraft.

NASA Technical Reports Server (NTRS)

Spera, R. J.; Prickett, W. Z.; Garate, J. A.; Firth, W. L.

1971-01-01

Mission operations are presented for comet rendezvous and outer planet exploration NEP spacecraft employing in-core thermionic reactors for electric power generation. The selected reference missions are the Comet Halley rendezvous and a Jupiter orbiter at 5.9 planet radii, the orbit of the moon Io. The characteristics of the baseline multi-mission NEP spacecraft are presented and its performance in other outer planet missions, such as Saturn and Uranus orbiters and a Neptune flyby, are discussed. Candidate mission operations are defined from spacecraft assembly to mission completion. Pre-launch operations are identified. Shuttle launch and subsequent injection to earth escape by the Centaur D-1T are discussed, as well as power plant startup and the heliocentric mission phases. The sequence and type of operations are basically identical for all missions investigated.

Hypervelocity impact physics

NASA Technical Reports Server (NTRS)

Schonberg, William P.; Bean, Alan J.; Darzi, Kent

1991-01-01

All large spacecraft are susceptible to impacts by meteoroids and orbiting space debris. These impacts occur at extremely high speed and can damage flight-critical systems, which can in turn lead to a catastrophic failure of the spacecraft. Therefore, the design of a spacecraft for a long-duration mission must take into account the possibility of such impacts and their effects on the spacecraft structure and on all of its exposed subsystems components. The work performed under the contract consisted of applied research on the effects of meteoroid/space debris impacts on candidate materials, design configurations, and support mechanisms of long term space vehicles. Hypervelocity impact mechanics was used to analyze the damage that occurs when a space vehicle is impacted by a micrometeoroid or a space debris particle. An impact analysis of over 500 test specimens was performed to generate by a hypervelocity impact damage database.

Planetary explorer liquid propulsion study

NASA Technical Reports Server (NTRS)

Mckevitt, F. X.; Eggers, R. F.; Bolz, C. W.

1971-01-01

An analytical evaluation of several candidate monopropellant hydrazine propulsion system approaches is conducted in order to define the most suitable configuration for the combined velocity and attitude control system for the Planetary Explorer spacecraft. Both orbiter and probe-type missions to the planet Venus are considered. The spacecraft concept is that of a Delta launched spin-stabilized vehicle. Velocity control is obtained through preprogrammed pulse-mode firing of the thrusters in synchronism with the spacecraft spin rate. Configuration selection is found to be strongly influenced by the possible error torques induced by uncertainties in thruster operation and installation. The propulsion systems defined are based on maximum use of existing, qualified components. Ground support equipment requirements are defined and system development testing outlined.

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

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

Strong non-radial propagation of energetic electrons in solar corona

NASA Astrophysics Data System (ADS)

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

2018-06-01

Analyzing the sequence of solar energetic electron events measured at both STEREO-A (STA) and STEREO-B (STB) spacecraft during 17-21 July 2014, when their orbital separation was 34°, we found evidence of a strong non-radial electron propagation in the solar corona below the solar wind source surface. The impulsive electron events were associated with recurrent flare and jet (hereafter flare/jet) activity at the border of an isolated coronal hole situated close to the solar equator. We have focused our study on the solar energetic particle (SEP) event on 17 July 2014, during which both spacecraft detected a similar impulsive and anisotropic energetic electron event suggesting optimal connection of both spacecraft to the parent particle source, despite the large angular separation between the parent flare and the nominal magnetic footpoints on the source surface of STA and STB of 68° and 90°, respectively. Combining the remote-sensing extreme ultraviolet (EUV) observations, in-situ plasma, magnetic field, and energetic particle data we investigated and discuss here the origin and the propagation trajectory of energetic electrons in the solar corona. We find that the energetic electrons in the energy range of 55-195 keV together with the associated EUV jet were injected from the flare site toward the spacecraft's magnetic footpoints and propagate along a strongly non-radial and inclined magnetic field below the source surface. From stereoscopic (EUV) observations we estimated the inclination angle of the jet trajectory and the respective magnetic field of 63° ± 11° relative to the radial direction. We show how the flare accelerated electrons reach very distant longitudes in the heliosphere, when the spacecraft are nominally not connected to the particle source. This example illustrates how ballistic backmapping can occasionally fail to characterize the magnetic connectivity during SEP events. This finding also provides an additional mechanism (one among others), which may explain the origin of widespread SEP events.

LDEF materials results for spacecraft applications: Executive summary

NASA Astrophysics Data System (ADS)

Whitaker, A. F.; Dooling, D.

1995-03-01

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

LDEF materials results for spacecraft applications: Executive summary

NASA Technical Reports Server (NTRS)

Whitaker, A. F. (Compiler); Dooling, D. (Compiler)

1995-01-01

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

A review of electron bombardment thruster systems/spacecraft field and particle interfaces

NASA Technical Reports Server (NTRS)

Byers, D. C.

1978-01-01

Information on the field and particle interfaces of electron bombardment ion thruster systems was summarized. Major areas discussed were the nonpropellant particles, neutral propellant, ion beam, low energy plasma, and fields. Spacecraft functions and subsystems reviewed were solar arrays, thermal control systems, optical sensors, communications, science, structures and materials, and potential control.

Van Allen Probe Charging During the St. Patrick's Day Event

NASA Technical Reports Server (NTRS)

Parker, L. Neergaard; Minow, J. I.

2015-01-01

The geomagnetic storms on and around March 17, 2015 marked the largest storms seen in the declining phase of the solar cycle to date. We use the Helium Oxygen Proton Electron (HOPE) mass spectrometer on board the Van Allen Probe - A and B satellites to study in detail the charging effects seen on these spacecraft during this time. Ion particle flux data provides information on the magnitude of the charging events using the ion line charging signature due to low energy ions accelerated by the spacecraft potential. Electron flux observations are used to correlate the charging environment with variations in spacecraft potential through the event. We also investigate the density and temperature of ions and electrons during the time of the charging event.

Low energy stage study. Volume 2: Requirements and candidate propulsion modes. [orbital launching of shuttle payloads

NASA Technical Reports Server (NTRS)

1978-01-01

A payload mission model covering 129 launches, was examined and compared against the space transportation system shuttle standard orbit inclinations and a shuttle launch site implementation schedule. Based on this examination and comparison, a set of six reference missions were defined in terms of spacecraft weight and velocity requirements to deliver the payload from a 296 km circular Shuttle standard orbit to the spacecraft's planned orbit. Payload characteristics and requirements representative of the model payloads included in the regime bounded by each of the six reference missions were determined. A set of launch cost envelopes were developed and defined based on the characteristics of existing/planned Shuttle upper stages and expendable launch systems in terms of launch cost and velocity delivered. These six reference missions were used to define the requirements for the candidate propulsion modes which were developed and screened to determine the propulsion approaches for conceptual design.

Plasma source for spacecraft potential control

NASA Technical Reports Server (NTRS)

Olsen, R. C.

1983-01-01

A stable electrical ground which enables the particle spectrometers to measure the low energy particle populations was investigated and the current required to neutralize the spacecraft was measured. In addition, the plasma source for potential control (PSPO C) prevents high charging events which could affect the spacecraft electrical integrity. The plasma source must be able to emit a plasma current large enough to balance the sum of all other currents to the spacecraft. In ion thrusters, hollow cathodes provide several amperes of electron current to the discharge chamber. The PSPO C is capable of balancing the net negative currents found in eclipse charging events producing 10 to 100 microamps of electron current. The largest current required is the ion current necessary to balance the total photoelectric current.

Fire Signatures of Materials Used in Spacecraft Construction

NASA Technical Reports Server (NTRS)

Taylor, Christina

2003-01-01

The focus of my work this summer was fire safety, specifically determining fire signatures from the combustion of materials commonly found in the construction of spacecraft. This project was undertaken with the aim of addressing concerns for health and safety onboard spacecraft. Under certain conditions, burning electronics produce surprisingly large amounts of acrid smoke, release fine airborne particles and expel condensable aerosols. Similarly, some wire insulation and packing material evolves smoke when in contact with a hot surface. In the limited, enclosed space available on spacecraft, these combustion products may pose a nuisance at the very least - at worst, a hazard to health or equipment. There is also a concern for fire safety in early detection on spacecraft. Our goal for the summer was to determine the most effective methods to test the materials, develop a protocol for sampling, and generate samples for analysis. We restricted our testing to electronic components, packaging and insulation materials, and wire insulation materials.

Evaluation of a Conductive Elastomer Seal for Spacecraft

NASA Technical Reports Server (NTRS)

Daniels, C. C.; Mather, J. L.; Oravec, H. A.; Dunlap, P. H., Jr.

2016-01-01

An electrically conductive elastomer was evaluated as a material candidate for a spacecraft seal. The elastomer used electrically conductive constituents as a means to reduce the resistance between mating interfaces of a sealed joint to meet spacecraft electrical bonding requirements. The compound's outgassing levels were compared against published NASA requirements. The compound was formed into a hollow O-ring seal and its compression set was measured. The O-ring seal was placed into an interface and the electrical resistance and leak rate were quantified. The amount of force required to fully compress the test article in the sealing interface and the force needed to separate the joint were also measured. The outgassing and resistance measurements were below the maximum allowable levels. The room temperature compression set and leak rates were fairly high when compared against other typical spacecraft seal materials, but were not excessive. The compression and adhesion forces were desirably low. Overall, the performance of the elastomer compound was sufficient to be considered for future spacecraft seal applications.

Validation of ISS Floating Potential Measurement Unit Electron Densities and Temperatures

NASA Technical Reports Server (NTRS)

Coffey, Victoria N.; Minow, Joseph I.; Parker, Linda N.; Bui, Them; Wright, Kenneth, Jr.; Koontz, Steven L.; Schneider, T.; Vaughn, J.; Craven, P.

2007-01-01

Validation of the Floating Potential Measurement Unit (FPMU) electron density and temperature measurements is an important step in the process of evaluating International Space Station spacecraft charging issues .including vehicle arcing and hazards to crew during extravehicular activities. The highest potentials observed on Space Station are due to the combined VxB effects on a large spacecraft and the collection of ionospheric electron and ion currents by the 160 V US solar array modules. Ionospheric electron environments are needed for input to the ISS spacecraft charging models used to predict the severity and frequency of occurrence of ISS charging hazards. Validation of these charging models requires comparing their predictions with measured FPMU values. Of course, the FPMU measurements themselves must also be validated independently for use in manned flight safety work. This presentation compares electron density and temperatures derived from the FPMU Langmuir probes and Plasma Impedance Probe against the independent density and temperature measurements from ultraviolet imagers, ground based incoherent scatter radar, and ionosonde sites.

Active experiments in space plasmas; Symposium D4.1 of Commission D, COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

NASA Technical Reports Server (NTRS)

Rietveld, M. T. (Editor)

1995-01-01

Papers from the conference are presented and cover the following topics: ion and electron beams; ionospheric modification; spacecraft interactions; chemical releases; and plasma waves. Auroras and plasma emissions are reported from electron beam injection experiments on the EXCEDE 3 rocket and APEX satellite respectively. The important parameters affecting the charging of spacecraft during the operation of electron guns is covered. The Active Magnetospheric Particle Acceleration Satellite (AMPAS) mission utilizing dual-payload tethered satellites and both up and downward directed electron beams is proposed to study the magnetosphere. Recent results and associated theories from the Sura, Arecibo and Troms ionospheric heating facitlites are presented. The effects of neutral gases on spacecraft charging are examined in a series of rocket flights. Many results from the Combined Release and Radiation Effects Satellite chemical release experiments are presented.

Probing the solar corona with very long baseline interferometry.

PubMed

Soja, B; Heinkelmann, R; Schuh, H

2014-06-20

Understanding and monitoring the solar corona and solar wind is important for many applications like telecommunications or geomagnetic studies. Coronal electron density models have been derived by various techniques over the last 45 years, principally by analysing the effect of the corona on spacecraft tracking. Here we show that recent observational data from very long baseline interferometry (VLBI), a radio technique crucial for astrophysics and geodesy, could be used to develop electron density models of the Sun's corona. The VLBI results agree well with previous models from spacecraft measurements. They also show that the simple spherical electron density model is violated by regional density variations and that on average the electron density in active regions is about three times that of low-density regions. Unlike spacecraft tracking, a VLBI campaign would be possible on a regular basis and would provide highly resolved spatial-temporal samplings over a complete solar cycle.

Development of electrical test procedures for qualification of spacecraft against EID. Volume 1: The CAN test and other relevant data

NASA Technical Reports Server (NTRS)

Wilkenfeld, J. M.; Judge, R. J. R.; Harlacher, B. L.

1982-01-01

A combined experimental and analytical program to develop system electrical test procedures for the qualification of spacecraft against damage produced by space-electron-induced discharges (EID) occurring on spacecraft dielectric outer surfaces is described. The data on the response of a simple satellite model, called CAN, to electron-induced discharges is presented. The experimental results were compared to predicted behavior and to the response of the CAN to electrical injection techniques simulating blowoff and arc discharges. Also included is a review of significant results from other ground tests and the P78-2 program to form a data base from which is specified those test procedures which optimally simulate the response of spacecraft to EID. The electrical and electron spraying test data were evaluated to provide a first-cut determination of the best methods for performance of electrical excitation qualification tests from the point of view of simulation fidelity.

Multi-Planetary Systems: Observations and Models of Dynamical Interactions

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.

2018-01-01

More than 600 multi-planet systems are known. The vast majority of these systems have been discovered by NASA's Kepler spacecraft, but dozens were found using the Doppler technique, the first multi-exoplanet system was identified through pulsar timing, and the most massive system has been found using imaging. More than one-third of the 4000+ planet candidates found by NASA's Kepler spacecraft are associated with target stars that have more than one planet candidate, and the large number of such Kepler "multis" tells us that flat multiplanet systems like our Solar System are common. Virtually all of Kepler candidate multis are stable, as tested by numerical integrations that assume a physically motivated mass-radius relationship. Statistical studies performed on these candidate systems reveal a great deal about the architecture of planetary systems, including the typical spacing of orbits and flatness. The characteristics of several of the most interesting confirmed multi-exoplanet systems will also be discussed.HR 8799's four massive planets orbit tens of AU from their host star and travel on nearly circular orbits. PSR B1257+12 has three much smaller planets orbiting close to a neutron star. Both represent extremes and show that planet formation is a robust process that produces a diversity of outcomes. Although both exomoons and Trojan (triangle Lagrange point) planets have been searched for, neither has yet been found.

Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Egedal, J.; Le, A.; Daughton, W.

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

Spacecraft Observations and Analytic Theory of Crescent-Shaped Electron Distributions in Asymmetric Magnetic Reconnection

DOE PAGES

Egedal, J.; Le, A.; Daughton, W.; ...

2016-10-24

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

The Hughes HS601HP spacecraft power subsystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krummann, W.; Ayvazian, H.

1998-07-01

The introduction of the Hughes HS 601HP (high power) spacecraft product line continuous the highly successful HS601 three axis stabilized geosynchronus spacecraft with increased power capabilities for larger payload applications. The enhanced power capabilities of the HS 601HP are built upon the heritage of 29 HS601 spacecraft presently in operation. The HS 601HP accommodates payload power ranges of 3 to 7 kilowatts and provides a smooth transition from the lower power HS 601 spacecraft to the HS 702 spacecraft, which has a payload capability up to 13 kilowatts. The HS 601HP spacecraft is designed for a 15 year life withmore » minimal operator interaction. The HS 601HP power subsystem provides a regulated power bus with a voltage range of 52 to 53 volts during all operational phases. The power subsystem is tailored to the specific needs of the spacecraft by selecting standard products from the HS 601HP power catalog. The solar arrays, battery, power control electronics and power distribution electronics are all modular and configurable to the requirements of the spacecraft. The HS 601HP solar array is the primary power source for the spacecraft. The solar array is comprised of two sets of planar solar panels (solar wings) which track the sun in a single spacecraft axis. The solar cells are selected from three different types based upon the spacecraft power generation requirements; silicon, single junction gallium arsenide or dual junction gallium arsenide. The maximum power capability at end of life (15 years, summer solstice) ranges from 4 to 7.7 kilowatts for the three types of solar cells. The HS 601HP battery is the power source for the spacecraft during eclipse and peak sunlight power periods. The battery is comprised of four individual battery packs connected in series to produce a single battery. Each battery pack can accommodate a maximum of eight battery cells with a capacity of 350 ampere-hours. The battery pack also provides for mounting of all electronics utilized by the battery, such as cell bypassing. The power electronics for the HS 601HP spacecraft provide for a tightly regulated power bus whether in sunlight or eclipse (battery discharge) operation. The bus voltage during sunlight is maintained by two bus voltage limiters (BVL), located on the yoke of each solar wing. The BVL maintains the regulated power bus at 52.9 volts by shunting excess solar wing power when not required by the spacecraft. The bus voltage during eclipse is maintained by two battery power controllers (BPC) located on the spacecraft bus shelf. The BPC maintains the regulated power bus at 52.2 volts during battery discharge and also provides for battery charging when excess solar array power is available. The power from the solar array or battery is distributed to the spacecraft by bus and payload power distribution units (PDU). The HS 601HP spacecraft product line now has three spacecraft in orbit. The first was launched in early November of 1997 with the second and third launched in late November and early December of 1997, respectively. The power systems are performing as designed and correlate well with the predicted performance calculations. Several more HS 601HP are scheduled to launch during 1998.« less

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

NASA Technical Reports Server (NTRS)

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

1981-01-01

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

Nitinol 60 as a Material For Spacecraft Triboelements

NASA Technical Reports Server (NTRS)

Pepper, Stephen V.; DellaCorte, Christopher; Noebe, Ronald D.; Hall, David R.; Glennon, Glenn

2009-01-01

The mechanical properties of Nitinol 60, 60 w/o Ni, 40 w/oTi (55 a/o Ni, 45 a/o Ti) are sufficiently attractive to warrant its consideration as a lubricated spacecraft triboelement. The ability to lubricate Nitinol 60 by the oils usually used on spacecraft mechanisms--Pennzane 2001A, Krytox 143AC and Castrol 815Z - was experimentally determined. These oils were run in the boundary lubrication regime for Nitinol 60 balls running against a 440C steel counterface in the vacuum spiral orbit tribometer. Test results consisting of the coefficient of friction versus time (friction traces) and relative degradation rates are presented. Contrary to the inability to successfully lubricate other metal alloys with high titanium content, it was found that Nitinol 60 is able to be lubricated by these oils. Overall, the results presented here indicate that Nitinol 60 is a credible candidate material for spacecraft bearing applications.

Solid propulsion advanced concepts

NASA Technical Reports Server (NTRS)

Nakamura, Y.; Shafer, J. I.

1972-01-01

The feasibility and application of a solid propulsion powered spacecraft concept to implement high energy missions independent of multiplanetary swingby opportunities are assessed and recommendations offered for future work. An upper stage, solid propulsion launch vehicle augmentation system was selected as the baseline configuration in view of the established program goals of low cost and high reliability. Spacecraft and propulsion system data that characterize mission performance capabilities were generated to serve as the basis for subsequent tradeoff studies. A cost effectiveness model was used for the preliminary feasibility assessment to provide a meaningful comparative effectiveness measure of the various candidate designs. The results substantiated the feasibility of the powered spacecraft concept when used in conjunction with several intermediate-sized launch vehicles as well as the existence of energy margins by which to exploit the attainment of extended mission capabilities. Additionally, in growth option applications, the employment of advanced propulsion systems and alternate spacecraft approaches appear promising.

Numerical Simulations of Spacecraft Charging: Selected Applications

NASA Astrophysics Data System (ADS)

Moulton, J. D.; Delzanno, G. L.; Meierbachtol, C.; Svyatskiy, D.; Vernon, L.; Borovsky, J.; Thomsen, M. F.

2016-12-01

The electrical charging of spacecraft due to bombarding charged particles affects their performance and operation. We study this charging using CPIC, a particle-in-cell code specifically designed for studying plasma-material interactions. CPIC is based on multi-block curvilinear meshes, resulting in near-optimal computational performance while maintaining geometric accuracy. It is interfaced to a mesh generator that creates a computational mesh conforming to complex objects like a spacecraft. Relevant plasma parameters can be imported from the SHIELDS framework (currently under development at LANL), which simulates geomagnetic storms and substorms in the Earth's magnetosphere. Selected physics results will be presented, together with an overview of the code. The physics results include spacecraft-charging simulations with geometry representative of the Van Allen Probes spacecraft, focusing on the conditions that can lead to significant spacecraft charging events. Second, results from a recent study that investigates the conditions for which a high-power (>keV) electron beam could be emitted from a magnetospheric spacecraft will be presented. The latter study proposes a spacecraft-charging mitigation strategy based on the plasma contactor technology that might allow beam experiments to operate in the low-density magnetosphere. High-power electron beams could be used for instance to establish magnetic-field-line connectivity between ionosphere and magnetosphere and help solving long-standing questions in ionospheric/magnetospheric physics.

Method and apparatus for calibrating the ionosphere and application to surveillance of geophysical events

NASA Technical Reports Server (NTRS)

Macdoran, P. F. (Inventor)

1984-01-01

The columnar electron content of the ionosphere between a spacecraft and a receiver is measured in realtime by cross correlating two coherently modulated signals transmitted at different frequencies (L1,L2) from the spacecraft to the receiver using a cross correlator. The time difference of arrival of the modulated signals is proportional to electron content of the ionosphere. A variable delay is adjusted relative to a fixed delay in the respective channels (L1,L2) to produce a maximum at the cross correlator output. The difference in delay required to produce this maximum is a measure of the columnar electron content of the ionosphere. A plurality of monitoring stations and spacecraft (Global Positioning System satellites) are employed to locate any terrestrial event that produces an ionospheric disturbance.

In-flight calibration of the Cluster PEACE sensors

NASA Astrophysics Data System (ADS)

Doss, N.; Fazakerley, A. N.; Mihaljčić, B.; Lahiff, A. D.; Wilson, R. J.; Kataria, D.; Rozum, I.; Watson, G.; Bogdanova, Y.

2014-05-01

The Plasma Electron and Current Experiment (PEACE) instruments operate on all four of the Cluster spacecraft and measure the 3-D velocity distribution of electrons in the energy range from 0.59 eV to 26.4 keV during each spacecraft spin. Pitch angle distributions and moments of the velocity distribution are also produced. As the mission has progressed, the efficiency of the detectors has declined. Several factors may play a role in this decline such as exposure to radiation, high electron fluxes and spacecraft thruster firings. To account for these variations, continuous in-flight calibration work is essential. The purpose of this paper is to describe the PEACE calibration parameters, focussing in particular on those that vary over time, and to describe the methods which are used to determine their evolution.

In-flight calibration of the Cluster PEACE sensors

NASA Astrophysics Data System (ADS)

Doss, N.; Fazakerley, A. N.; Mihaljčić, B.; Lahiff, A. D.; Wilson, R. J.; Kataria, D.; Rozum, I.; Watson, G.; Bogdanova, Y.

2013-10-01

The Plasma Electron and Current Experiment (PEACE) instruments operate on all four of the Cluster spacecraft and measure the 3-D velocity distribution of electrons in the energy range from 0.59 eV to 26.4 keV during each spacecraft spin. Pitch angle distributions and moments of the velocity distribution are also produced. As the mission progresses the efficiency of the detectors has declined. Several factors may play a role in this decline such as exposure to radiation, high electron fluxes and spacecraft thruster firings. To account for these variations, continuous in-flight calibration work is essential. The purpose of this paper is to describe the PEACE calibration parameters, focussing in particular on those that vary over time, and to describe the methods which are used to determine their evolution.

Nanocomposites in Multifuntional Structures for Spacecraft Platforms

NASA Astrophysics Data System (ADS)

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

2012-07-01

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

Energy spectra variations of high energy electrons in magnetic storms observed by ARASE and HIMAWARI

NASA Astrophysics Data System (ADS)

Takashima, T.; Higashio, N.; Mitani, T.; Nagatsuma, T.; Yoshizumi, M.

2017-12-01

The ARASE spacecraft was launched in December 20, 2016 to investigate mechanisms for acceleration and loss of relativistic electrons in the radiation belts during space storms. The six particle instruments with wide energy range (a few eV to 10MeV) are onboard the ARASE spacecraft. Especially, two particle instruments, HEP and XEP observe high energy electron with energy range from 70keV to over 10Mev. Those instruments observed several geomagnetic storms caused by coronal hole high speed streams or coronal mass ejections from March in 2017. The relativistic electrons in the outer radiation belt were disappeared/increased and their energy spectra were changed dynamically in some storms observed by XEP/HEP onboard the ARASE spacecraft. In the same time, SEDA-e with energy range 200keV-4.5MeV for electron on board the HIMAWARI-8, Japanese weather satellite on GEO, observed increase of relativistic electron in different local time. We will report on energy spectra variations of high energy electrons including calibrations of differential flux between XEP and HEP and discuss comparisons with energy spectra between ARAE and HIMAWARI that observed each storm in different local time.

The SCOPE mission

NASA Astrophysics Data System (ADS)

Fujimoto, Masaki

In order to open the new horizon of research in the Plasma Universe, SCOPE will perform simultaneous multi-scale observations that enables data-based study on the key space plasma processes from the cross-scale coupling point of view. The key processes to be studied are magnetic reconnection under various boundary conditions, shocks in space plasma, collisionless plasma mixing at the boundaries, and physics of current sheets embedded in complex magnetic geometries. The orbit is equatorial, 10x25 Re, such that in-situ observations of the above key processes are possible. The SCOPE mission is made up of a pair of mother-daughter spacecraft and a three spacecraft formation. The spacecraft pair will zoom-in to the microphysics while the spacecraft formation will observe macro-scale dynamics surrouding the key region to be studied by the mother-daughter pair. The mother spacecraft is equipped with a full suite of particle detector including ultra-high sampling cycle electron detector. The daughter spacecraft remains near ( 10km) the mother spacecraft and the spacecraft-pair will focus on wave-particle interaction utilizing inter-spacecraft communication. The inter-spacecraft distance of the for-mation varies from below 100km to above 3000km so that surrounding dynamics at various scales (electron, ion and MHD) can be studied. While the core part of the mission is planned to be a CSA-JAXA (Canada-Japan) collaboration, further international collaborations to en-hance the science return of the mission are welcome.

Reference earth orbital research and applications investigations (blue book). Volume 7: Technology

NASA Technical Reports Server (NTRS)

1971-01-01

The candidate experiment program for manned space stations with specific application to technology disciplines is presented. The five functional program elements are devoted to the development of new technology for application to future generation spacecraft and experiments. The functional program elements are as follows: (1) monitor and trace movement of external contaminants to determine methods for controlling contamination, (2) analysis of fundamentals of fluid systems management, (3) extravehicular activity, (4) advanced spacecraft systems tests, and (5) development of teleoperator system for use with space activities.

Vice President Pence Tours NASA’s Historic Mission Control in Houston

NASA Image and Video Library

2017-06-07

On June 7, Vice President Mike Pence joined NASA’s Acting Administrator Robert Lightfoot and Johnson Space Center Director Ellen Ochoa to announce the 12 men and women who were selected to the 2017 astronaut class from more than 18,300 applicants. The new astronaut candidates could one day be performing research on the International Space Station, launching from American soil aboard spacecraft built by American companies, and traveling to the moon or even Mars with the help of NASA’s new Orion spacecraft and Space Launch System rocket.

Investigation of Possible Electromagnetic Disturbances caused by Spacecraft-Plasma Interactions at 4 Radii

NASA Technical Reports Server (NTRS)

Okada, M.; Tsurutani, B. T.; Goldstein, G. E.; Matsumoto, H.; Brinca, A. L.; Kellogg, P. J.

1995-01-01

The proposed Small Solar Probe mission features a close approach to the sun with a perihelion of 4 radii. Carbon molecules emitted from the spacecraft's heat shield will become ionized by electron impact and photoionization. The newly created ions and electrons may generate electromagnetic and electrostatic plasma waves which are possible sources of interference with in-situ plasma measurements.

Calibration Results and Anticipated Science Ops for the Parker Solar Probe's SWEAP/SPAN-Electron Analyzers

NASA Astrophysics Data System (ADS)

Whittlesey, P. L.; Larson, D. E.; Livi, R.; Abiad, R.; Parker, C.; Halekas, J. S.; Kasper, J. C.; Korreck, K. E.

2017-12-01

We present the SPAN-E calibration results and science operation plans this instrument on the Parker Solar Probe mission. SPAN-E is a pair of highly configurable ESA sensors, one on the RAM side of the spacecraft (SPAN-Ae) and one on anti-RAM (SPAN-B). Together, SPAN-E will jointly measure the full 3D thermal and suprathermal electron distribution function at cadences as fast as 4.58Hz. Joined with the SPAN-Ai and SPC instruments that are part of the Solar Wind Electrons, Alphas, and Protons (SWEAP) suite, SPAN-E will measure the solar coronal plasma across a range of energies and densities with a FOV over >90% of the sky, returning data over a 7 year long PSP mission lifetime. The SPAN-E instruments have passed environmental testing at the instrument level, and the final instrument calibrations are complete. This presentation details the final instrument calibration results as performed at UCB/SSL after environmental testing, and details the planned configurations for PSP's first orbit. In addition, the PSP spacecraft's magnetic fields are expected to distort the measured electron VDFs at low energies, thus we present a novel computer vision method of measuring and modeling the spacecraft magnetic fields as seen during an observatory-level "swing" test. Ultimately, the model will feed into an algorithm for ground corrections to electron VDFs distorted by these stray spacecraft magnetic fields.

Microsatellite Digital Magnetometer SMILE - Present State and Future Trends

NASA Astrophysics Data System (ADS)

Belyayev, Serhiy; Ivchenko, Nickolay

2010-05-01

The fluxgate magnetometers (FGM) are probably the most widespread instruments used onboard spacecrafts for both scientific and service purposes. The recent trend to decrease the weight and size of the spacecrafts requires creating as small as possible but enough sensitive FGM. A joint Swedish-Ukrainian team made the development of such a magnetometer and as the result the Small Magnetometer In Low mass Experiment (SMILE) - a digital fluxgate microsatellite magnetometer - was created [1]. Majority of electronic units of this FGM were combined in a digital integrated circuit - a Field Programmable Gate Array (FPGA). The FPGA provides full processing (determined by a digital correlation algorithm) of amplified and digitized fluxgate sensor output signals and provides both FGM output data and feedback signals. Such digital design makes the instrument very flexible, reduces power consumption and opens possibilities for customization of the operation modes. It allows miniaturizing the electronic unit and, together with the smallest in the world low noise three-component fluxgate sensor with the side dimension of 20 mm and weight about 20 grams only, the small but enough sensitive space qualified FGM is created. SMILE magnetometer was successfully flown onboard the NASA Cascades-2 sounding rocket, and is to fly in the LAPLander package onboard the ESA REXUS-8 student sounding rocket [2]. Unfortunately, such a design of electronic circuit does not allow us to realize all possibilities of the miniature sensor. The separate tests of the sensor with highest-class analog electronics showed that its noise level may be reduced to as low value as 10…15 picoTesla at 1 Hz. Also the use of volume compensation in the sensor provides high geometrical stability of the axes and improved performance compared to component compensated sensors. The measured parameters appear to be comparable or even better than these of best stationary FGM and, if realized in small enough volume and weight, such a sensitive but small FGM could be a good candidate for planned Lunar missions where the weight is the major restriction factor. This stimulated further research in the direction of the analysis and elimination of noise sources of digital design, as well as of the optimization of FGM electronic circuit structure. The description of the obtained results of the electronic unit upgrade and recent FGM model tests are given and future improvement directions are discussed. These works are partially supported by NSAU contract No. 1499. References: 1. Åke Forslund, Serhiy Belyayev, Nickolay Ivchenko, Göran Olsson, Terry Edberg and Andriy Marusenkov, Miniaturized digital fluxgate magnetometer for small spacecraft applications 2008 Meas. Sci. Technol. 19 2. T. Sundberg, N. Ivchenko, D. Borglund, P. Ahlen, M. Gustavsson, C. Jonsson, J. Juhlen, O. Neunet, J. Sandstrom, E. Sund, M. Wartelski, C. Westlund, L. Xin, Small Recoverable Payload for Deployable Sounding Rocket Experiments. ESA Special Publication SP671

Evaluation of Electronic Writing Experiences of Turkish Teacher Candidates at WATTPAD Environment

ERIC Educational Resources Information Center

Aytan, Talat

2017-01-01

The purpose of this study is to analyze Turkish teacher candidates' electronic writing experiences at wattpad.com environment. The study group of this research consisted of 53 Turkish teacher candidates who were studying at a state university in Istanbul. Teacher candidates in the study group joined Wattpad.com and wrote at least one narrative…

Evaluation of COTS Electronic Parts for Extreme Temperature Use in NASA Missions

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Hammoud, Ahmad; Elbuluk, Malik

2008-01-01

Electronic systems capable of extreme temperature operation are required for many future NASA space exploration missions where it is desirable to have smaller, lighter, and less expensive spacecraft and probes. Presently, spacecraft on-board electronics are maintained at about room temperature by use of thermal control systems. An Extreme Temperature Electronics Program at the NASA Glenn Research Center focuses on development of electronics suitable for space exploration missions. The effects of exposure to extreme temperatures and thermal cycling are being investigated for commercial-off-the-shelf components as well as for components specially developed for harsh environments. An overview of this program along with selected data is presented.

Electronic Systems for Spacecraft Vehicles: Required EDA Tools

NASA Technical Reports Server (NTRS)

Bachnak, Rafic

1999-01-01

The continuous increase in complexity of electronic systems is making the design and manufacturing of such systems more challenging than ever before. As a result, designers are finding it impossible to design efficient systems without the use of sophisticated Electronic Design Automation (EDA) tools. These tools offer integrated simulation of the electrical, mechanical, and manufacturing functions and lead to a correct by design methodology. This report identifies the EDA tools that would be needed to design, analyze, simulate, and evaluate electronic systems for spacecraft vehicles. In addition, the report presents recommendations to enhance the current JSC electronic design capabilities. This includes cost information and a discussion as to the impact, both positive and negative, of implementing the recommendations.

Investigation of plasma-surface interaction effects on pulsed electrostatic manipulation for reentry blackout alleviation

NASA Astrophysics Data System (ADS)

Krishnamoorthy, S.; Close, S.

2017-03-01

The reentry blackout phenomenon affects most spacecraft entering a dense planetary atmosphere from space, due to the presence of a plasma layer that surrounds the spacecraft. This plasma layer is created by ionization of ambient air due to shock and frictional heating, and in some cases is further enhanced due to contamination by ablation products. This layer causes a strong attenuation of incoming and outgoing electromagnetic waves including those used for command and control, communication and telemetry over a period referred to as the ‘blackout period’. The blackout period may last up to several minutes and is a major contributor to the landing error ellipse at best, and a serious safety hazard in the worst case, especially in the context of human spaceflight. In this work, we present a possible method for alleviation of reentry blackout using electronegative DC pulses applied from insulated electrodes on the reentry vehicle’s surface. We study the reentry plasma’s interaction with a DC pulse using a particle-in-cell (PIC) model. Detailed models of plasma-insulator interaction are included in our simulations. The absorption and scattering of ions and electrons at the plasma-dielectric interface are taken into account. Secondary emission from the insulating surface is also considered, and its implications on various design issues is studied. Furthermore, we explore the effect of changing the applied voltage and the impact of surface physics on the creation and stabilization of communication windows. The primary aim of this analysis is to examine the possibility of restoring L- and S-band communication from the spacecraft to a ground station. Our results provide insight into the effect of key design variables on the response of the plasma to the applied voltage pulse. Simulations show the creation of pockets where electron density in the plasma layer is reduced three orders of magnitude or more in the vicinity of the electrodes. These pockets extend to distances up to three times the electrode length normal to the vehicle surface. Based on our results, we postulate that pulsed electrostatic manipulation (PEM) may be a viable candidate for reentry blackout alleviation in the future.

Juno Taking Shape

NASA Image and Video Library

2010-04-06

Assembly began April 1, 2010, for NASA Juno spacecraft. Workers at Lockheed Martin Space Systems in Denver, Colorado are moving into place the vault that will protect the spacecraft sensitive electronics from Jupiter intense radiation belts.

Inspecting Juno Radiation Vault

NASA Image and Video Library

2010-07-12

A technician inspects the special radiation vault being installed atop the propulsion module of NASA Juno spacecraft; the vault has titanium walls to protect the spacecraft electronic brain and heart from Jupiter harsh radiation environment.

Analysis of differential and active charging phenomena on ATS-5 and ATS-6

NASA Technical Reports Server (NTRS)

Olsen, R. C.; Whipple, E. C., Jr.

1980-01-01

Spacecraft charging on the differential charging and artificial particle emission experiments on ATS 5 and ATS 6 were studied. Differential charging of spacecraft surfaces generated large electrostatic barriers to spacecraft generated electrons, from photoemission, secondary emission, and thermal emitters. The electron emitter could partially or totally discharge the satellite, but the mainframe recharged negatively in a few 10's of seconds. The time dependence of the charging behavior was explained by the relatively large capacitance for differential charging in comparison to the small spacecraft to space capacitance. A daylight charging event on ATS 6 was shown to have a charging behavior suggesting the dominance of differential charging on the absolute potential of the mainframe. Ion engine operations and plasma emission experiments on ATS 6 were shown to be an effective means of controlling the spacecraft potential in eclipse and sunlight. Elimination of barrier effects around the detectors and improving the quality of the particle data are discussed.

High-spatial-resolution electron density measurement by Langmuir probe for multi-point observations using tiny spacecraft

NASA Astrophysics Data System (ADS)

Hoang, H.; Røed, K.; Bekkeng, T. A.; Trondsen, E.; Clausen, L. B. N.; Miloch, W. J.; Moen, J. I.

2017-11-01

A method for evaluating electron density using a single fixed-bias Langmuir probe is presented. The technique allows for high-spatio-temporal resolution electron density measurements, which can be effectively carried out by tiny spacecraft for multi-point observations in the ionosphere. The results are compared with the multi-needle Langmuir probe system, which is a scientific instrument developed at the University of Oslo comprising four fixed-bias cylindrical probes that allow small-scale plasma density structures to be characterized in the ionosphere. The technique proposed in this paper can comply with the requirements of future small-sized spacecraft, where the cost-effectiveness, limited space available on the craft, low power consumption and capacity for data-links need to be addressed. The first experimental results in both the plasma laboratory and space confirm the efficiency of the new approach. Moreover, detailed analyses on two challenging issues when deploying the DC Langmuir probe on a tiny spacecraft, which are the limited conductive area of the spacecraft and probe surface contamination, are presented in the paper. It is demonstrated that the limited conductive area, depending on applications, can either be of no concern for the experiment or can be resolved by mitigation methods. Surface contamination has a small impact on the performance of the developed probe.

Early results of the ionospheric experiment of the Apollo-Soyuz Test Project

NASA Technical Reports Server (NTRS)

Grossi, M. D.; Gay, R. H.

1976-01-01

A description is presented of a spacecraft-to-spacecraft Doppler-tracking experiment which was performed by the Smithsonian Astrophysical Observatory on the occasion of the Apollo-Soyuz Test Project (ASTP). The experiment involved the measurement of the relative velocity between the ASTP docking module and the Apollo command service module by a Doppler-tracking method. The objectives of the ionospheric experiment include the measurement of the time changes of the columnar electron content between the two spacecraft. The obtained data can provide a basis for the determination of the horizontal gradients of electron density at the height of 220 km.

Representation of the Geosynchronous Plasma Environment in Spacecraft Charging Calculations

NASA Technical Reports Server (NTRS)

Davis, V. A.; Mandell, M. J.; Thomsen, M. F.

2006-01-01

Historically, our ability to predict and postdict spacecraft surface charging has been limited by the characterization of the plasma environment. One difficulty lies in the common practice of fitting the plasma data to a Maxwellian or Double Maxwellian distribution function, which may not represent the data well for charging purposes. We use electron and ion flux spectra measured by the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzer (MPA) to examine how the use of different spectral representations of the charged particle environment in computations of spacecraft potentials during magnetospheric substorms affects the accuracy of the results. We calculate the spacecraft potential using both the measured fluxes and several different fits to these fluxes. These measured fluxes have been corrected for the difference between the measured and calculated potential. The potential computed using the measured fluxes and the best available material properties of graphite carbon, with a secondary electron escape fraction of 81%, is within a factor of three of the measured potential for 87% of the data. Potentials calculated using a Kappa function fit to the incident electron flux distribution function and a Maxwellian function fit to the incident ion flux distribution function agree with measured potentials nearly as well as do potentials calculated using the measured fluxes. Alternative spectral representations gave less accurate estimates of potential. The use of all the components of the net flux, along with spacecraft specific average material properties, gives a better estimate of the spacecraft potential than the high energy flux alone.

Upsets related to spacecraft charging

NASA Astrophysics Data System (ADS)

Frederickson, A. R.

1996-04-01

The charging of spacecraft components by high energy radiation can result in spontaneous pulsed discharges. The pulses can interrupt normal operations of spacecraft electronics. The 20-year history of ground studies and spacecraft studies of this phenomenon are reviewed. The data from space are not sufficient to unambiguously point to a few specific solutions. The ground based data continue to find more problem areas the longer one looks. As spacecraft become more complex and carry less radiation shielding, the charging and discharging of insulators is becoming a more critical problem area. Ground experiments indicate that solutions for spacecraft are multiple and diverse, and many technical details are reviewed or introduced here.

Medium-energy particle experiments—electron analyzer (MEP-e) for the exploration of energization and radiation in geospace (ERG) mission

NASA Astrophysics Data System (ADS)

Kasahara, Satoshi; Yokota, Shoichiro; Mitani, Takefumi; Asamura, Kazushi; Hirahara, Masafumi; Shibano, Yasuko; Takashima, Takeshi

2018-05-01

The medium-energy particle experiments—electron analyzer onboard the exploration of energization and radiation in geospace spacecraft measures the energy and direction of each incoming electron in the energy range of 7-87 keV. The sensor covers a 2 π-radian disklike field of view with 16 detectors, and the full solid angle coverage is achieved through the spacecraft's spin motion. The electron energy is independently measured by both an electrostatic analyzer and avalanche photodiodes, enabling significant background reduction. We describe the technical approach, data output, and examples of initial observations.[Figure not available: see fulltext.

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

NASA Technical Reports Server (NTRS)

Dekany, Justin; Christensen, Justin; Dennison, J. R.; Jensen, Amberly Evans; Wilson, Gregory; Schneider, Todd; Bowers, Charles W.; Meloy, Robert

2015-01-01

Many contemporary spacecraft materials exhibit cathodoluminescence when exposed to electron flux from the space plasma environment. A quantitative, physics-based model has been developed to predict the intensity of the total glow as a function of incident electron current density and energy, temperature, and intrinsic material properties. We present a comparative study of the absolute spectral radiance for more than 20 types of dielectric and composite materials based on this model which spans more than three orders of magnitude. Variations in intensity are contrasted for different electron environments, different sizes of samples and sample sets, different testing and analysis methods, and data acquired at different test facilities. Together, these results allow us to estimate the accuracy and precision to which laboratory studies may be able to determine the response of spacecraft materials in the actual space environment. It also provides guidance as to the distribution of emissions that may be expected for sets of similar flight hardware under similar environmental conditions.

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

NASA Technical Reports Server (NTRS)

Dekany, Justin; Christensen, Justin; Dennison, J. R.; Jensen, Amberly Evans; Wilson, Gregory; Schneider, Todd A.; Bowers, Charles W.; Meloy, Robert

2014-01-01

Many contemporary spacecraft materials exhibit cathodoluminescence when exposed to electron flux from the space plasma environment. A quantitative, physics-based model has been developed to predict the intensity of the glow as a function of incident electron current density and energy, temperature, and intrinsic material properties. We present a comparative study of the absolute spectral radiance for several types of dielectric and composite materials based on this model which spans three orders of magnitude. Variations in intensity are contrasted for different electron environments, different sizes of samples and sample sets, different testing and analysis methods, and data acquired at different test facilities. Together, these results allow us to estimate the accuracy and precision to which laboratory studies may be able to determine the response of spacecraft materials in the actual space environment. It also provides guidance as to the distribution of emissions that may be expected for sets of similar flight hardware under similar environmental conditions.

Comparative study of cross-field and field-aligned electron beams in active experiments. [in upper atmosphere

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Pritchett, P. L.

1988-01-01

Beam-plasma interactions associated with the cross-field and field-aligned injection of electron beams from spacecraft were investigated using a two-dimensional (three velocity component) electrostatic particle simulations. It is shown that the beam properties and plasma response can be characterized well by the ratio between the stagnation time and the plasma response time, which depends on the ratio of the ambient plasma density to the beam density, the beam width, the beam energy, and the spacecraft length. It was found that the beams injected across the field lines tend to lose their coherence after about one or two gyrations due to space-charge oscillations induced by the beam, irrespective of the spacecraft charging. These oscillations scatter the beam electrons into a hollow cylinder of a radius equal to a beam electron gyroradius and thickness of the order of two beam Debye lengths. Parallel injected beams are subjected to similar oscillations, which cause the beam to expand to fill a solid cylinder of a comparable thickness.

Active experiments in space plasmas; Symposium D4.1 of Commission D, COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

NASA Astrophysics Data System (ADS)

Rietveld, M. T.

1995-07-01

Papers from the conference are presented and cover the following topics: ion and electron beams; ionospheric modification; spacecraft interactions; chemical releases; and plasma waves. Auroras and plasma emissions are reported from electron beam injection experiments on the EXCEDE 3 rocket and APEX satellite respectively. The important parameters affecting the charging of spacecraft during the operation of electron guns is covered. The Active Magnetospheric Particle Acceleration Satellite (AMPAS) mission utilizing dual-payload tethered satellites and both up and downward directed electron beams is proposed to study the magnetosphere. Recent results and associated theories from the Sura, Arecibo and Troms ionospheric heating facitlites are presented. The effects of neutral gases on spacecraft charging are examined in a series of rocket flights. Many results from the Combined Release and Radiation Effects Satellite chemical release experiments are presented. For individual titles, see A95-83500 through A95-83535.

MMS Observation of Magnetic Reconnection in the Turbulent Magnetosheath

NASA Astrophysics Data System (ADS)

Vörös, Z.; Yordanova, E.; Varsani, A.; Genestreti, K. J.; Khotyaintsev, Yu. V.; Li, W.; Graham, D. B.; Norgren, C.; Nakamura, R.; Narita, Y.; Plaschke, F.; Magnes, W.; Baumjohann, W.; Fischer, D.; Vaivads, A.; Eriksson, E.; Lindqvist, P.-A.; Marklund, G.; Ergun, R. E.; Leitner, M.; Leubner, M. P.; Strangeway, R. J.; Le Contel, O.; Pollock, C.; Giles, B. J.; Torbert, R. B.; Burch, J. L.; Avanov, L. A.; Dorelli, J. C.; Gershman, D. J.; Paterson, W. R.; Lavraud, B.; Saito, Y.

2017-11-01

In this paper we use the full armament of the MMS (Magnetospheric Multiscale) spacecraft to study magnetic reconnection in the turbulent magnetosheath downstream of a quasi-parallel bow shock. Contrarily to the magnetopause and magnetotail cases, only a few observations of reconnection in the magnetosheath have been reported. The case study in this paper presents, for the first time, both fluid-scale and kinetic-scale signatures of an ongoing reconnection in the turbulent magnetosheath. The spacecraft are crossing the reconnection inflow and outflow regions and the ion diffusion region (IDR). Inside the reconnection outflows D shape ion distributions are observed. Inside the IDR mixing of ion populations, crescent-like velocity distributions and ion accelerations are observed. One of the spacecraft skims the outer region of the electron diffusion region, where parallel electric fields, energy dissipation/conversion, electron pressure tensor agyrotropy, electron temperature anisotropy, and electron accelerations are observed. Some of the difficulties of the observations of magnetic reconnection in turbulent plasma are also outlined.

Energy regeneration model of self-consistent field of electron beams into electric power*

NASA Astrophysics Data System (ADS)

Kazmin, B. N.; Ryzhov, D. R.; Trifanov, I. V.; Snezhko, A. A.; Savelyeva, M. V.

2016-04-01

We consider physic-mathematical models of electric processes in electron beams, conversion of beam parameters into electric power values and their transformation into users’ electric power grid (onboard spacecraft network). We perform computer simulation validating high energy efficiency of the studied processes to be applied in the electric power technology to produce the power as well as electric power plants and propulsion installation in the spacecraft.

Radiation effects in spacecraft electronics

NASA Technical Reports Server (NTRS)

Raymond, James P.

1989-01-01

Effects on the internal spacecraft electronics due to exposure to the natural and enhanced space radiation environment will be reviewed. The emphasis will be placed on the description of the nature of both the exposure environment and failure mechanisms in semiconductors. Understanding both the system environment and device effects is critical in the use of laboratory simulation environments to obtain the data necessary to design and qualify components for successful application.

Space Weathering Experiments on Spacecraft Materials

NASA Technical Reports Server (NTRS)

Engelhart, D. P.; Cooper, R.; Cowardin, H.; Maxwell, J.; Plis, E.; Ferguson, D.; Barton, D.; Schiefer, S.; Hoffmann, R.

2017-01-01

A project to investigate space environment effects on specific materials with interest to remote sensing was initiated in 2016. The goal of the project is to better characterize changes in the optical properties of polymers found in multi-layered spacecraft insulation (MLI) induced by electron bombardment. Previous analysis shows that chemical bonds break and potentially reform when exposed to high energy electrons like those seen in orbit. These chemical changes have been shown to alter a material's optical reflectance, among other material properties. This paper presents the initial experimental results of MLI materials exposed to various fluences of high energy electrons, designed to simulate a portion of the geosynchronous Earth orbit (GEO) space environment. It is shown that the spectral reflectance of some of the tested materials changes as a function of electron dose. These results provide an experimental benchmark for analysis of aging effects on satellite systems which can be used to improve remote sensing and space situational awareness. They also provide preliminary analysis on those materials that are most likely to comprise the high area-to-mass ratio (HAMR) population of space debris in the geosynchronous orbit environment. Finally, the results presented in this paper serve as a proof of concept for simulated environmental aging of spacecraft polymers that should lead to more experiments using a larger subset of spacecraft materials.

Active experiments in modifying spacecraft potential: Results from ATS-5 and ATS-6

NASA Technical Reports Server (NTRS)

Olsen, R. C.; Whipple, E. C.

1979-01-01

The processing of data from onboard spacecraft instruments are described. The modification of spacecraft potentials is reviewed. Analysis of this data yielded the following results: (1) electron emission (E approximately 10 electron-volts) did not perturb the status of a satellite at low potential the absolute value of phi approximately 50 volts by more than 50 volts (the ATS 5 low energy limit), (2) emission of a low energy plasma (E approximatey 10 volts) does not change low potentials (the absolute value of phi approximately 5 volts) by more than a few volts (ATS 6 low energy resolution), (3) when ATS 6 entered eclipse in the presence of a high energy plasma (10 keV), the neutralizer suppressed any rise in the absolute value of phi (within a few volts resolution), (4) when the electron emitter on ATS 5 operated, it served to discharge negative potentials from thousands to hundreds of volts, and (5) when the neutralizer on ATS 6 was operated, it served to discharge kilovolt potentials to below 50 volts. Low altitude (100 - 300 km) experiments with KV electron beams are studied. Differential charging was eliminated by the operation of the main thruster on ATS 6 clamped on the spacecraft at -5 volts.

Physiological responses of astronaut candidates to simulated +Gx orbital emergency re-entry.

PubMed

Wu, Bin; Xue, Yueying; Wu, Ping; Gu, Zhiming; Wang, Yue; Jing, Xiaolu

2012-08-01

We investigated astronaut candidates' physiological and pathological responses to +Gx exposure during simulated emergency return from a running orbit to advance astronaut +Gx tolerance training and medical support in manned spaceflight. There were 13 male astronaut candidates who were exposed to a simulated high +Gx acceleration profile in a spacecraft during an emergency return lasting for 230 s. The peak value was 8.5 G. Subjective feelings and symptoms, cardiovascular and respiratory responses, and changes in urine component before, during, and after +Gx exposure were investigated. Under high +Gx exposure, 15.4% of subjects exhibited arrhythmia. Heart rate (HR) increased significantly and four different types of HR response curves were distinguished. The ratio of QT to RR interval on the electrocardiograms was significantly increased. Arterial oxygen saturation (SaO2) declined with increasing G value and then returned gradually. SaO2 reached a minimum (87.7%) at 3 G during the decline phase of the +Gx curve. Respiratory rate increased significantly with increasing G value, while the amplitude and area of the respiratory waves were significantly reduced. The overshoot appeared immediately after +Gx exposure. A few subjects suffered from slight injuries, including positive urine protein (1/13), positive urinary occult blood (1/13), and a large area of petechiae on the back (1/13). Astronaut candidates have relatively good tolerance to the +Gx profile during a simulation of spacecraft emergent ballistic re-entry. However, a few subjects exhibited adverse physiological responses and slight reversible pathological injuries.

Fire toxicology program. JSC methodology

NASA Technical Reports Server (NTRS)

Schneider, H.; Bafus, D.

1978-01-01

Toxicological testing of spacecraft materials was initiated in 1965. Toxicological evaluations of the pyrolysis/combustion products of candidate spacecraft materials were performed using a modified 142 liter Bethlehem Chamber equipped with a Linberg Model 55031 furnace external to the chamber. In all of the assessments, lethality was chosen as the endpoint. A new pyrolysis/combustion chamber was developed for toxicological testing and ranking of both spacecraft and aircraft materials. The pyrolysis/combustion chamber permits the use of both behavior and physiological measurements as indicators of incapacitation. Methods were developed which employ high resolution gas chromatography/mass spectrometry to generate chamber atmospheric profiles which indicate the reproductibility of pyrolysate concentrations. The atmospheric volatile profiles in combination with CO, CO2, and O2 analysis indicates that small chamber equipped with an internal furnace will give reproducible results.

Foam core shield (FCS) systems : a new dual - purpose technology for shielding against meteoroid strike damage and for thermal control of spacecrafts/satellite components

NASA Technical Reports Server (NTRS)

Adams, Marc A.; Zwissler, James G.; Hayes, Charles; Fabensky, Beth; Cornelison, Charles; Alexander, Lesley; Bishop, Karen

2005-01-01

A new technology is being developed that can protect spacecraft and satellite components against damage from meteoroid strikes and control the thermal environment of the protected components. This technology, called Foam Core Shield (FCS) systems, has the potential to replace the multi-layer insulation blankets (MLI) that have been used on spacecraft for decades. In order to be an attractive candidate for replacing MLI, FCS systems should not only provide superior protection against meteoroid strikes but also provide an equal or superior ability to control the temperature of the protected component. Properly designed FCS systems can provide these principal functions, meteoroid strike protection and thermal control, with lower system mass and a smaller system envelope than ML.

Negative Ion Chemistry in the Coma of Comet 1P/Halley

NASA Technical Reports Server (NTRS)

Cordiner, M. A.; Charnley, S. B.

2012-01-01

Negative ions (anions) were identified in the coma of comet 1P/Halley from in-situ measurements performed by the Giotto spacecraft in 1986. These anions were detected with masses in the range 7-110 amu, but with insufficient mass resolution to permit unambiguous identification. We present details of a new chemical-hydrodynamic model for the coma of comet Halley that includes - for the first time - atomic and molecular anions, in addition to a comprehensive hydrocarbon chemistry. Anion number densities arc calculated as a function of radius in the coma, and compared with the Giotto results. Important anion production mechanisms arc found to include radiative electron attachment, polar photodissociation, dissociative electron attachment, and proton transfer. The polyyne anions C4H(-) and C6H(-) arc found to be likely candidates to explain the Giotto anion mass spectrum in the range 49-73 amu. Thc CN(-) anion probably makes a significant contribution to the mass spectrum at 26 amu. Larger carbon-chain anions such as C8H(1) can explain the peak near 100 amu provided there is a source of large carbon-chain-bearing molecules from the cometary nucleus.

MIT's role in project Apollo. Volume 2: Optical, radar, and candidate subsystems

NASA Technical Reports Server (NTRS)

1972-01-01

The development of optical, radar, and candidate subsystems for Project Apollo is discussed. The design and development of the optical subsystems for both the Apollo command and lunar spacecraft are described. Design approaches, problems, and solutions are presented. The evolution of radar interfaces with the GN&C system is discussed; these interfaces involved both hardware and software in a relatively complex interrelationship. The design and development of three candidate subsystems are also described. The systems were considered for use in Apollo, but were not incorporated into the final GN&C system. The three subsystems discussed are the star tracker-horizon photometer, the map and data viewer and the lunar module optical rendezvous system.

Candidate configuration trade study, Stellar-Inertial Measurement System (SIMS) for an Earth Observation Satellite (EOS), addendum

NASA Technical Reports Server (NTRS)

White, R.; Grant, F.

1973-01-01

Results are given of an investigation of the effects of spacecraft orbital ephemeris and attitude errors on the ability to determine the locations of unknown landmarks with respect to known landmarks in the payload sensor imagery.

Satellite Search and Rescue System Studies: Alarm and Position Reporting.

DTIC Science & Technology

alarm and position reporting ( ALPR ) techniques, and the operational or planned spacecraft which might be available for piggybacking the ALPR payload...Several system concepts were then developed to perform the ALPR functions. The candidates were screened and the preferred system concepts were chosen

Materials for Low-Energy Neutron Radiation Shielding

NASA Technical Reports Server (NTRS)

Singleterry, Robert C., Jr.; Thibeault, Sheila A.

2000-01-01

Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

Comet nucleus sample return mission

NASA Technical Reports Server (NTRS)

1983-01-01

A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

Ground Deployment Demonstration and Material Testing for Solar Sail

NASA Astrophysics Data System (ADS)

Huang, Xiaoqi; Cheng, Zhengai; Liu, Yufei; Wang, Li

2016-07-01

Solar Sail is a kind of spacecraft that can achieve extremely high velocity by light pressure instead of chemical fuel. The great accelerate rely on its high area-to-mass ratio. So solar sail is always designed in huge size and it use ultra thin and light weight materials. For 100-meter class solar sail, two key points must be considered in the design process. They are fold-deployment method, and material property change in space environment. To test and verify the fold-deployment technology, a 8*8m principle prototype was developed. Sail membrane folding in method of IKAROS, Nanosail-D , and new proposed L-shape folding pattern were tested on this prototype. Their deployment properties were investigated in detail, and comparisons were made between them. Also, the space environment suitability of ultra thin polyimide films as candidate solar sail material was analyzed. The preliminary test results showed that membrane by all the folding method could deploy well. Moreover, sail membrane folding by L-shape pattern deployed more rapidly and more organized among the three folding pattern tested. The mechanical properties of the polyimide had no significant change after electron irradiation. As the preliminary research on the key technology of solar sail spacecraft, in this paper, the results of the study would provide important basis on large-scale solar sail membrane select and fold-deploying method design.

Different Approaches for Ensuring Performance/Reliability of Plastic Encapsulated Microcircuits (PEMs) in Space Applications

NASA Technical Reports Server (NTRS)

Gerke, R. David; Sandor, Mike; Agarwal, Shri; Moor, Andrew F.; Cooper, Kim A.

2000-01-01

Engineers within the commercial and aerospace industries are using trade-off and risk analysis to aid in reducing spacecraft system cost while increasing performance and maintaining high reliability. In many cases, Commercial Off-The-Shelf (COTS) components, which include Plastic Encapsulated Microcircuits (PEMs), are candidate packaging technologies for spacecrafts due to their lower cost, lower weight and enhanced functionality. Establishing and implementing a parts program that effectively and reliably makes use of these potentially less reliable, but state-of-the-art devices, has become a significant portion of the job for the parts engineer. Assembling a reliable high performance electronic system, which includes COTS components, requires that the end user assume a risk. To minimize the risk involved, companies have developed methodologies by which they use accelerated stress testing to assess the product and reduce the risk involved to the total system. Currently, there are no industry standard procedures for accomplishing this risk mitigation. This paper will present the approaches for reducing the risk of using PEMs devices in space flight systems as developed by two independent Laboratories. The JPL procedure involves primarily a tailored screening with accelerated stress philosophy while the APL procedure is primarily, a lot qualification procedure. Both Laboratories successfully have reduced the risk of using the particular devices for their respective systems and mission requirements.

Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection

NASA Technical Reports Server (NTRS)

Eriksson, S.; Wilder, F. D.; Ergun, R. E.; Schwartz, S. J.; Cassak, P. A.; Burch, J. L.; Chen, Li-Jen; Torbert, R. B.; Phan, T. D.; Lavraud, B.;

ANTS: A New Concept for Very Remote Exploration with Intelligent Software Agents

NASA Astrophysics Data System (ADS)

Clark, P. E.; Curtis, S.; Rilee, M.; Truszkowski, W.; Iyengar, J.; Crawford, H.

2001-12-01

ANTS (Autonomous Nano-Technology Swarm), a NASA advanced mission concept, is a large (100 to 1000 member) swarm of pico-class (1 kg) totally autonomous spacecraft that prospect the asteroid belt. As the capacity and complexity of hardware and software, and the sophistication of technical and scientific goals have increased, greater cost constraints have led to fewer resources and thus, the need to operate spacecraft with less frequent contact. At present, autonomous operation of spacecraft systems allows great capability of spacecraft to 'safe' themselves when conditions threaten spacecraft safety. To further develop spacecraft capability, NASA is at the forefront of Intelligent Software Agent (ISA) research, performing experiments in space and on the ground to advance deliberative and collaborative autonomous control techniques. Selected missions in current planning stages require small groups of spacecraft to cooperate at a tactical level to select and schedule measurements to be made by appropriate instruments to characterize rapidly unfolding real-time events on a routine basis. The next level of development, which we are considering here, is in the use of ISAs at a strategic level, to explore the final, remote frontiers of the solar system, potentially involving a large class of objects with only infrequent contact possible. Obvious mission candidates are mainbelt asteroids, a population consisting of more than a million small bodies. Although a large fraction of solar system objects are asteroids, little data is available for them because the vast majority of them are too small to be observed except in close proximity. Asteroids originated in the transitional region between the inner (rocky) and outer (solidified gases) solar system, have remained largely unmodified since formation, and thus have a more primitive composition which includes higher abundances of siderophile (metallic iron-associated) elements and volatiles than other planetary surfaces. As a result, there has been interest in asteroids as sources of exploitable resources. Far more reconnaissance is required before such a program is undertaken. A traditional mission approach (to explore larger asteroids sequentially) is not adequate for determining the systematic distribution of exploitable material in the asteroid population. Our approach involves the use of distributed intelligence in a swarm of tiny spacecraft, each with specialized instrument capability (e.g., advanced computing, imaging, spectrometry, etc.) to evaluate the resource potential of the entire population. Supervised clusters of spacecraft will operate simultaneously within a broadly defined framework of goals to select targets (>1000) from among available candidates and to develop scenarios for studying targets simultaneously. Spacecraft use solar sails to fly directly to asteroids 1 kilometer or greater in diameter. Selected swarm members return to Earth with data, replacements join the swarm as needed. We would like to acknowledge our students R. Watson, V. Cox, and F. Olukomo for their support of this work.

Failures and anomalies attributed to spacecraft charging

NASA Technical Reports Server (NTRS)

Leach, R. D.; Alexander, M. B. (Editor)

1995-01-01

The effects of spacecraft charging can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are protected against charging is an important engineering function necessary to assure mission success. Spacecraft charging is expected to have a significant role in future space activities and programs. Objectives of this reference publication are to present a brief overview of spacecraft charging, to acquaint the reader with charging history, including illustrative cases of charging anomalies, and to introduce current spacecraft charging prevention activities of the Electromagnetics and Environments Branch, Marshall Space Flight Center (MSFC), National Aeronautics and Space Administration (NASA).

Spacecraft-environment interaction model cross comparison applied to Solar Probe Plus

NASA Astrophysics Data System (ADS)

Lapenta, G.; Deca, J.; Markidis, S.; Marchand, R.; Guillemant, S.; Matéo Vélez, J.; Miyake, Y.; Usui, H.; Ergun, R.; Sturner, A. P.

2013-12-01

Given that our society becomes increasingly dependent on space technology, it is imperative to develop a good understanding of spacecraft-plasma interactions. Two main issues are important. First, one needs to be able to design a reliable spacecraft that can survive in the harsh solar wind conditions, and second a very good knowledge of the behaviour and plasma structure around the spacecraft is required to be able to interpret and correct measurements from onboard instruments and science experiments. In this work we present the results of a cross-comparison study between five spacecraft-plasma models (EMSES, iPic3D, LASP, PTetra, SPIS) used to simulate the interaction of the Solar Probe Plus (SPP) satellite with the space environment under representative solar wind conditions near perihelion. The purpose of this cross-comparison is to assess the consistency and validity of the different numerical approaches from the similarities and differences of their predictions under well defined conditions, with attention to the implicit PIC code iPic3D, which has never been used for spacecraft-environment interaction studies before. The physical effects considered are spacecraft charging, photoelectron and secondary electron emission, the presence of a background magnetic field and density variations. The latter of which can cause the floating potential of SPP to go from negative to positive or visa versa, depending on the solar wind conditions, and spacecraft material properties. Simulation results are presented and compared with increasing levels of complexity in the physics to evaluate the sensitivity of the model predictions to certain physical effects. The comparisons focus particularly on spacecraft floating potential, detailed contributions to the currents collected and emitted by the spacecraft, and on the potential and density spatial profiles near the satellite. Model predictions obtained with our different computational approaches are found to be in good agreement when the physical processes are treated similarly. The comparisons considered here indicate that, with the correct parameterization of important physical effects such as photoemission and secondary electron emission, our simulation models should have the required skill to predict details of satellite-plasma interaction physics with a high level of confidence. This work was supported by the International Space Science Institute in Bern Switzerland. The potential profile around the Solar Probe Plus spacecraft in orbital flow, from the iPic3D code. The physical model includes photo- and secondary electrons and a static magnetic field.

Internal Charging

NASA Technical Reports Server (NTRS)

Minow, Joseph I.

2014-01-01

(1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.

Spacecraft Heat Rejection Methods: Active and Passive Heat Transfer for Electronic Systems.

DTIC Science & Technology

1986-08-29

Storage in avionics, spacecraft and electronics ,;"ters. Microencapsulated phase change materials (PCMs) in a two-component water SlUrrv- were useo with...capsules was observed in the pumping process. Inaddition, both microencapsulated and pure PCM were used to passively reduce tile tempera- tuo .tremes of...conducted as a Phase I Small Business Innovation Research (SBIR) program to explore the feasibility of using microencapsulated phase change materials (PCM) in

Long life assurance study for manned spacecraft long life hardware. Volume 2: Long life assurance studies of EEE parts and packaging

NASA Technical Reports Server (NTRS)

1972-01-01

Guidelines for the design, development, and fabrication of electronic components and circuits for use in spacecraft construction are presented. The subjects discussed involve quality control procedures and test methodology for the following subjects: (1) monolithic integrated circuits, (2) hybrid integrated circuits, (3) transistors, (4) diodes, (5) tantalum capacitors, (6) electromechanical relays, (7) switches and circuit breakers, and (8) electronic packaging.

Estimating the Reliability of Electronic Parts in High Radiation Fields

NASA Technical Reports Server (NTRS)

Everline, Chester; Clark, Karla; Man, Guy; Rasmussen, Robert; Johnston, Allan; Kohlhase, Charles; Paulos, Todd

2008-01-01

Radiation effects on materials and electronic parts constrain the lifetime of flight systems visiting Europa. Understanding mission lifetime limits is critical to the design and planning of such a mission. Therefore, the operational aspects of radiation dose are a mission success issue. To predict and manage mission lifetime in a high radiation environment, system engineers need capable tools to trade radiation design choices against system design and reliability, and science achievements. Conventional tools and approaches provided past missions with conservative designs without the ability to predict their lifetime beyond the baseline mission.This paper describes a more systematic approach to understanding spacecraft design margin, allowing better prediction of spacecraft lifetime. This is possible because of newly available electronic parts radiation effects statistics and an enhanced spacecraft system reliability methodology. This new approach can be used in conjunction with traditional approaches for mission design. This paper describes the fundamentals of the new methodology.

High-level spacecraft charging in the low-altitude polar auroral environment

NASA Astrophysics Data System (ADS)

Gussenhoven, M. S.; Hardy, D. A.; Rich, F.; Burke, W. J.; Yeh, H.-C.

1985-11-01

Regions of intense keV electron precipitation, such as inverted-V structures, at times colocate with ionospheric plasma depletion regions in the high-latitude polar ionosphere. When Defense Meteorological Satellite Program (DMSP) F6 and F7 satellites, at 840 km, enter these regions in darkness, ion signatures of high spacecraft-to-ambient plasma potential differences (several hundred volts negative) are observed with the new SSJ/4 ion detectors. A systematic survey of charging events and the environment in which they occur was made using the DMSP F6 and F7 precipitating ion and electron detectors, the SSIE thermal plasma probes, and the SSM (F7 only) vector magnetometer. The charging events of November 26, 1983, are analyzed in detail since they occurred on both satellites. Critical levels of number flux and average energy for the precipitating electrons, and the threshold density of the thermal ionospheric ions are defined for different levels of spacecraft charging.

The nighttime ionosphere of Mars from Mars-4 and Mars-5 radio occultation dual-frequency measurements

NASA Technical Reports Server (NTRS)

Savich, N. A.; Samovol, V. A.; Vasilyev, M. B.; Vyshlov, A. S.; Samoznaev, L. N.; Sidorenko, A. I.; Shtern, D. Y.

1976-01-01

Dual frequency radio sounding of the Martian nighttime ionosphere was carried out during the exits from behind the planet of the Mars-4 spacecraft on February 2, 1974 and the Mars-5 spacecraft on February 18, 1974. In these experiments, the spacecraft transmitter emitted two coherent monochromatic signals in decimeter and centimeter wavelength ranges. At the Earth receiving station, the reduced phase difference (or frequencies) of these signals was measured. The nighttime ionosphere of Mars measured in both cases had a peak electron density of approximately 5 X 1,000/cu cm at an altitude of 110 to 130 km. At the times of spacecraft exit, the solar zenith angles at the point of occultation were 127 deg and 106 deg, respectively. The height profiles of electron concentration were obtained assuming spherical symmetry of the Martian ionosphere.

Plasma distribution and spacecraft charging modeling near Jupiter

NASA Technical Reports Server (NTRS)

Goldstein, R.; Divine, N.

1977-01-01

To assess the role of spacecraft charging near Jupiter, the plasma distribution in Jupiter's magnetosphere was modeled using data from the plasma analyzer experiments on Pioneer 10 (published results) and on Pioneer 11 (preliminary results). In the model, electron temperatures are kT = 4 eV throughout, whereas proton temperatures range over 100 or equal to kT or equal to 400 eV. The model fluxes and concentrations vary over three orders of magnitude among several corotating regions, including, in order to increasing distance from Jupiter, a plasma void, plasma sphere, sporadic zone, ring current, current sheet, high latitude plasma and magnetosheath. Intermediate and high energy electrons and protons (to 100 MeV) are modeled as well. The models supply the information for calculating particle fluxes to a spacecraft in the Jovian environment. The particle balance equations (including effects of secondary and photoemission) then determine the spacecraft potential.

Embedded Thermal Control for Spacecraft Subsystems Miniaturization

NASA Technical Reports Server (NTRS)

Didion, Jeffrey R.

2014-01-01

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

Spacecraft Charge Monitor

NASA Astrophysics Data System (ADS)

Goembel, L.

2003-12-01

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

The electron distribution function downstream of the solar-wind termination shock: Where are the hot electrons?

NASA Astrophysics Data System (ADS)

Fahr, Hans J.; Richardson, John D.; Verscharen, Daniel

2015-07-01

In the majority of the literature on plasma shock waves, electrons play the role of "ghost particles", since their contribution to mass and momentum flows is negligible, and they have been treated as only taking care of the electric plasma neutrality. In some more recent papers, however, electrons play a new important role in the shock dynamics and thermodynamics, especially at the solar-wind termination shock. They react on the shock electric field in a very specific way, leading to suprathermal nonequilibrium distributions of the downstream electrons, which can be represented by a kappa distribution function. In this paper, we discuss why this anticipated hot electron population has not been seen by the plasma detectors of the Voyager spacecraft downstream of the solar-wind termination shock. We show that hot nonequilibrium electrons induce a strong negative electric charge-up of any spacecraft cruising through this downstream plasma environment. This charge reduces electron fluxes at the spacecraft detectors to nondetectable intensities. Furthermore, we show that the Debye length λDκ grows to values of about λDκ/λD ≃ 106 compared to the classical value λD in this hot-electron environment. This unusual condition allows for the propagation of a certain type of electrostatic plasma waves that, at very large wavelengths, allow us to determine the effective temperature of the suprathermal electrons directly by means of the phase velocity of these waves. At moderate wavelengths, the electron-acoustic dispersion relation leads to nonpropagating oscillations with the ion-plasma frequency ωp, instead of the traditional electron plasma frequency.

Long life assurance study for manned spacecraft long life hardware. Volume 4: Special long life assurance studies

NASA Technical Reports Server (NTRS)

1972-01-01

Guidelines for the selection of equipment to be used for manned spacecraft in order to assure a five year maintenance-free service life were developed. A special study was conducted to determine the adequacy of the procedures used to determine the quality and effectiveness of various components. The subjects examined are: (1) temperature cycling for acceptance of electronic assemblies; (2) accelerated testing techniques; (3) electronic part screening techniques; (4) electronic part derating practices; (5) vibration life extension of printed circuit board assemblies; and (6) tolerance funnelling and test requirements.

On-orbit damage detection and health monitoring of large space trusses: Status and critical issues

NASA Technical Reports Server (NTRS)

Kashangaki, Thomas A. L.

1991-01-01

The long lifetimes, delicate nature and stringent pointing requirements of large space structures such as Space Station Freedom and geostationary Earth sciences platforms might require that these spacecraft be monitored periodically for possible damage to the load carrying structures. A review of the literature in damage detection and health monitoring of such structures is presented, along with a candidate structure to be used as a testbed for future work in this field. A unified notation and terminology is also proposed to facilitate comparisons between candidate methods.

Changes of the Electrical and Optical Character of Polyimide Films Due to Exposure to High Energy GEO-like Electrons and the Chemistry that Drives it

NASA Astrophysics Data System (ADS)

Hoffmann, R.; Cooper, R.; Ferguson, D.

As a result of the interaction between the spacecraft and its operational environment, the constituent materials begin to change. These changes are determined by a combination of: chemical reactions, contamination, and energy deposition. They can range in severity from negligible to total loss of the material. Virtually all properties of the material, the mechanical, optical/thermal, and electrical are altered in largely unknown ways from the pristine materials. This negatively impacts the ability of spacecraft operators to predict the behavior of a spacecraft as it ages its environment. For example, in the case of electrical conduction in polyimide, there is a three orders of magnitude decrease in the resistivity after only eight months of simulated GEO electron exposure. Optical changes in the material also dramatically impact the ability of ground based optical observations to identify and track both known and unknown spacecraft. We will be presenting work done within the Spacecraft Charging and Instrument Calibration Lab at AFRL/RVB to quantify the changes in total reflection, BRDF, and electrical conduction of aluminized polyimide film after simulated aging in a GEO-like electron environment. We correlate these data with the chemical structure of the film as determined by XPS and NMR. A deeper, predictive understanding of how materials change will not only increase the operational lifetime of space assets by providing more accurate data to operators, it will improve SSA by allowing ground based observers to more accurately deduce component materials and determine how long a spacecraft has been in orbit.

MEMS based pumped liquid cooling systems for micro/nano spacecraft thermal control

NASA Technical Reports Server (NTRS)

Birur, G. C.; Shakkottai, P.; Sur, T. W.

2000-01-01

The electronic and other payload power densities in future micro/nano spacecraft are expected to exceed 25 Watts/cm(sup 2) and require advanced thermal control concepts and technologies to keep their payload within allowable temperature limits. This paper presents background on the need for pumped liquid cooling systems for future micro/nano spacecraft and results from this ongoing experimental investigation.

Spacecraft observations of a Maxwell Demon coating the separatrix of asymmetric magnetic reconnection with crescent-shaped electron distributions

NASA Astrophysics Data System (ADS)

Egedal, J.; Le, A.; Daughton, W.; Wetherton, B.; Cassak, Pa; Chen, Lj; Lavraud, B.; Dorell, J.; Avanov, L.; Gershman, D.

2016-10-01

During asymmetric magnetic reconnection in the dayside magnetopause in situ spacecraft mea- surements show that electrons from the high density inflow penetrate some distance into the low density inflow. Supported by a kinetic simulation, we present a general derivation of an exclusion energy parameter, which provides a lower kinetic energy bound for an electron to jump across the reconnection region from one inflow region to the other. As by a Maxwell Demon, only high energy electrons are permitted to cross the inner reconnection region, strongly impacting the form of the electron distribution function observed along the low density side separatrix. The dynamics produce two distinct flavors of crescent-shaped electron distributions in a thin boundary layer along the separatrix between the magnetospheric inflow and the reconnection exhaust. The analytical model presented relates these salient details of the distribution function to the electron dynamics in the inner reconnection region.

First Results from ARTEMIS, a New Two-Spacecraft Lunar Mission: Counter-Streaming Plasma Populations in the Lunar Wake

NASA Technical Reports Server (NTRS)

Halekas, J. S.; Angelopoulos, V.; Sibeck, D. G.; Khurana, K. K.; Russell, C. T.; Delory, G. T.; Farrell, W. M.; McFadden, J. P.; Bonnell, J. W.; Larson, D.;

First Results from ARTEMIS, A New Two-Spacecraft Lunar Mission: Counter-Streaming Plasma Populations in the Lunar Wake

NASA Technical Reports Server (NTRS)

Halekas, J. S.; Angelopoulos, V.; Sibeck, D. G.; Khurana, K. K.; Russell, C. T.; Delory, G. T.; Farrell, W. M.; McFadden, J. P.; Bonnell, J. W.; Larson, D.;

Proton radiation effects on the optical properties of vertically aligned carbon nanotubes

NASA Astrophysics Data System (ADS)

Kuhnhenn, J.; Khavrus, V.; Leonhardt, A.; Eversheim, D.; Noll, C.; Hinderlich, S.; Dahl, A.

2017-11-01

This paper discusses proton-induced radiation effects in vertically aligned carbon nanotubes (VA-CNT). VACNTs exhibit extremely low optical reflectivity which makes them interesting candidates for use in spacecraft stray light suppression. Investigating their behavior in space environment is a precondition for the implementation on a satellite.

The GIRE2 Model and Its Application to the Europa Mission

NASA Technical Reports Server (NTRS)

De Soria-Santacruz Pich, Maria; Garrett, Henry B.; Evans, Robin W.; Jun, Insoo; Kim, Wousik; Paranicas, Chris

2016-01-01

We present an empirical model of Jupiter's electron radiation environment and its application to the design of the future NASA mission to Europa. The model is based on data from the Galileo spacecraft. Measurements of the high-energy, omni-directional electrons from the Energetic Particle Detector (EPD) and magnetic field from the Magnetometer (MAG) onboard Galileo are used for this purpose. Ten-minute averages of the EPD data are used to provide an omni-directional electron flux spectrum at 0.238, 0.416, 0.706, 1.5, 2.0, and 11.0 MeV. Additionally, data from the Geiger Tube Telescope onboard Pioneer 10 and 11 are used to calculate the flux of 31 MeV electrons. The Galileo Interim Radiation Electron model v.2 (GIRE2) combines these datasets with the original Divine model and synchrotron observations to estimate the trapped electron radiation environment. Unlike the original Divine model, which was based on flybys of the Voyager and Pioneer spacecraft, the new GIRE2 model covers about 7 years of data and more than 30 orbits around Jupiter from the Galileo spacecraft. The model represents a step forward in the study of the Jovian radiation environment and is a valuable tool to assist in the design of future missions to Jupiter. This paper gives an overview of GIRE2 and focuses on its application to the design of the future NASA mission to Europa. The spacecraft will orbit Jupiter and perform multiple flybys of the moon Europa, which is embedded in the middle of a very strong radiation environment. The radiation environment surrounding the moon as well as along the trajectory are described in the paper together with the implications of this environment on the design of a mission.

MULTI-SPACECRAFT OBSERVATIONS AND TRANSPORT MODELING OF ENERGETIC ELECTRONS FOR A SERIES OF SOLAR PARTICLE EVENTS IN AUGUST 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

The Use of Langmuir Probes in Non-Maxwellian Space Plasmas

NASA Technical Reports Server (NTRS)

Hoegy, Walter R.; Brace, Larry H.

1998-01-01

Disturbance of the Maxwellian plasma may occur in the vicinity of a spacecraft due to photoemission, interactions between the spacecraft and thermospheric gases, or electron emissions from other devices on the spacecraft. Significant non-maxwellian plasma distributions may also occur in nature as a mixture of ionospheric and magnetospheric plasmas or secondaries produced by photoionization in the thermosphere or auroral precipitation. The general formulas for current collection (volt-ampere curves) by planar, cylindrical, and spherical Langmuir probes in isotropic and anisotropic non-maxwellian plasmas are examined. Examples are given of how one may identify and remove the non-maxwellian components in the Langmuir probe current to permit the ionospheric parameters to be determined. Theoretical volt-ampere curves presented for typical examples of non-maxwellian distributions include: two-temperature plasmas and a thermal plasma with an energetic electron beam. If the non-ionospheric electrons are Maxwellian at a temperature distinct from that of the ionosphere electrons, the volt-ampere curves can be fitted directly to obtain the temperatures and densities of both electron components without resorting to differenting the current. For an arbitrary isotropic distribution, the current for retarded particles is shown to be identical for the three geometries. For anisotropic distributions, the three probe geometries are not equally suited for measuring the ionospheric electron temperature and density or for determining the distribution function in the presence of non-maxwellian back-round electrons.

An Atmospheric Guidance Algorithm Testbed for the Mars Surveyor Program 2001 Orbiter and Lander

NASA Technical Reports Server (NTRS)

Striepe, Scott A.; Queen, Eric M.; Powell, Richard W.; Braun, Robert D.; Cheatwood, F. McNeil; Aguirre, John T.; Sachi, Laura A.; Lyons, Daniel T.

1998-01-01

An Atmospheric Flight Team was formed by the Mars Surveyor Program '01 mission office to develop aerocapture and precision landing testbed simulations and candidate guidance algorithms. Three- and six-degree-of-freedom Mars atmospheric flight simulations have been developed for testing, evaluation, and analysis of candidate guidance algorithms for the Mars Surveyor Program 2001 Orbiter and Lander. These simulations are built around the Program to Optimize Simulated Trajectories. Subroutines were supplied by Atmospheric Flight Team members for modeling the Mars atmosphere, spacecraft control system, aeroshell aerodynamic characteristics, and other Mars 2001 mission specific models. This paper describes these models and their perturbations applied during Monte Carlo analyses to develop, test, and characterize candidate guidance algorithms.

The Use of Liquid Isopropyl Alcohol and Hydrogen Peroxide Gas Plasma to Biologically Decontaminate Spacecraft Electronics

NASA Technical Reports Server (NTRS)

Bonner, J. K.; Tudryn, Carissa D.; Choi, Sun J.; Eulogio, Sebastian E.; Roberts, Timothy J.; Tudryn, Carissa D.

2006-01-01

Legitimate concern exists regarding sending spacecraft and their associated hardware to solar system bodies where they could possibly contaminate the body's surface with terrestrial microorganisms. The NASA approved guidelines for sterilization as set forth in NPG 8020.12C, which is consistent with the biological contamination control objectives of the Committee on Space Research (COSPAR), recommends subjecting the spacecraft and its associated hardware to dry heat-a dry heat regimen that could potentially employ a temperature of 110(deg)C for up to 200 hours. Such a temperature exposure could prove detrimental to the spacecraft electronics. The stimulated growth of intermetallic compounds (IMCs) in metallic interconnects and/or thermal degradation of organic materials composing much of the hardware could take place over a prolonged temperature regimen. Such detrimental phenomena would almost certainly compromise the integrity and reliability of the electronics. Investigation of sterilization procedures in the medical field suggests that hydrogen peroxide (H202) gas plasma (HPGP) technology can effectively function as an alternative to heat sterilization, especially for heat-sensitive items. Treatment with isopropyl alcohol (IPA) in liquid form prior to exposure of the hardware to HPGP should also prove beneficial. Although IPA is not a sterilant, it is frequently used as a disinfectant because of its bactericidal properties. The use of IPA in electronics cleaning is widely recognized and has been utilized for many years with no adverse affects reported. In addition, IPA is the principal ingredient of the test fluid used in ionic contamination testers to assess the amount of ionic contamination found on the surfaces of printed wiring assemblies. This paper will set forth experimental data confirming the feasibility of the IPA/H202 approach to reach acceptable microbial reduction (MR) levels of spacecraft electronic hardware. In addition, a proposed process flow in which both IPA liquid and HPGP are utilized will be presented in Section 7.0.

Cables and connectors for Large Space System Technology (LSST)

NASA Technical Reports Server (NTRS)

Dunbar, W. G.

1980-01-01

The effect of the environment and extravehicular activity/remote assembly operations on the cables and connectors for spacecraft with metallic and/or nonmetallic structures was examined. Cable and connector philosophy was outlined for the electrical systems and electronic compartments which contain high-voltage, high-power electrical and electronic equipment. The influence of plasma and particulates on the system is analyzed and the effect of static buildup on the spacecraft electrical system discussed. Conceptual cable and connector designs are assessed for capability to withstand high current and high voltage without danger of arcs and electromagnetic interference. The extravehicular activites required of the space station and/or supply spacecraft crew members to join and inspect the electrical system, using manual or remote assembly construction are also considered.

Prediction and measurement results of radiation damage to CMOS devices on board spacecraft

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.; Danchenko, V.; Cliff, R. A.; Sing, M.; Brucker, G. J.; Ohanian, R. S.

1977-01-01

Final results from the CMOS Radiation Effects Measurement (CREM) experiment flown on Explorer 55 are presented and discussed, based on about 15 months of observations and measurements. Conclusions are given relating to long-range annealing, effects of operating temperature on semiconductor performance in space, biased and unbiased P-MOS device degradation, unbiased n-channel device performance, changes in device transconductance, and the difference in ionization efficiency between Co-60 gamma rays and 1-Mev Van de Graaff electrons. The performance of devices in a heavily shielded electronic subsystem box within the spacecraft is evaluated and compared. Environment models and computational methods and their impact on device-degradation estimates are being reviewed to determine whether they permit cost-effective design of spacecraft.

The STEIN Particle Detector

DTIC Science & Technology

2015-02-27

cubesats. The CINEMA (Cubesat for Ions Neutrals Electrons and Magnetic 1 Approved for public release; distribution is unlimited. fields) was the primary...intended host for STEIN. Additionally some calibration efforts were performed with the CINEMA spacecraft as an element of the readout. This resulted...designed to accept a clock from its host spacecraft (as was the design case for CINEMA ) of 8.38MHz (specifically 2^23 Hz). As well as a spacecraft

Methodology and Data Sources for Assessing Extreme Charging Events within the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Parker, L. N.; Minow, J. I.; Talaat, E. R.

2016-12-01

Spacecraft surface and internal charging is a potential threat to space technologies because electrostatic discharges on, or within, charged spacecraft materials can result in a number of adverse impacts to spacecraft systems. The Space Weather Action Plan (SWAP) ionizing radiation benchmark team recognized that spacecraft charging will need to be considered to complete the ionizing radiation benchmarks in order to evaluate the threat of charging to critical space infrastructure operating within the near-Earth ionizing radiation environments. However, the team chose to defer work on the lower energy charging environments and focus the initial benchmark efforts on the higher energy galactic cosmic ray, solar energetic particle, and trapped radiation belt particle environments of concern for radiation dose and single event effects in humans and hardware. Therefore, an initial set of 1 in 100 year spacecraft charging environment benchmarks remains to be defined to meet the SWAP goals. This presentation will discuss the available data sources and a methodology to assess the 1 in 100 year extreme space weather events that drive surface and internal charging threats to spacecraft. Environments to be considered are the hot plasmas in the outer magnetosphere during geomagnetic storms, relativistic electrons in the outer radiation belt, and energetic auroral electrons in low Earth orbit at high latitudes.

Polarized-interferometer feasibility study

NASA Technical Reports Server (NTRS)

Raab, F. H.

1983-01-01

The feasibility of using a polarized-interferometer system as a rendezvous and docking sensor for two cooperating spacecraft was studied. The polarized interferometer is a radio frequency system for long range, real time determination of relative position and attitude. Range is determined by round trip signal timing. Direction is determined by radio interferometry. Relative roll is determined from signal polarization. Each spacecraft is equipped with a transponder and an antenna array. The antenna arrays consist of four crossed dipoles that can transmit or receive either circularly or linearly polarized signals. The active spacecraft is equipped with a sophisticated transponder and makes all measurements. The transponder on the passive spacecraft is a relatively simple repeater. An initialization algorithm is developed to estimate position and attitude without any a priori information. A tracking algorithm based upon minimum variance linear estimators is also developed. Techniques to simplify the transponder on the passive spacecraft are investigated and a suitable configuration is determined. A multiple carrier CW signal format is selected. The dependence of range accuracy and ambiguity resolution error probability are derived and used to design a candidate system. The validity of the design and the feasibility of the polarized interferometer concept are verified by simulation.

Mission Concept to Connect Magnetospheric Physical Processes to Ionospheric Phenomena

NASA Astrophysics Data System (ADS)

Dors, E. E.; MacDonald, E.; Kepko, L.; Borovsky, J.; Reeves, G. D.; Delzanno, G. L.; Thomsen, M. F.; Sanchez, E. R.; Henderson, M. G.; Nguyen, D. C.; Vaith, H.; Gilchrist, B. E.; Spanswick, E.; Marshall, R. A.; Donovan, E.; Neilson, J.; Carlsten, B. E.

2017-12-01

On the Earth's nightside the magnetic connections between the ionosphere and the dynamic magnetosphere have a great deal of uncertainty: this uncertainty prevents us from scientifically understanding what physical processes in the magnetosphere are driving the various phenomena in the ionosphere. Since the 1990s, the space plasma physics group at Los Alamos National Laboratory has been working on a concept to connect magnetospheric physical processes to auroral phenomena in the ionosphere by firing an electron beam from a magnetospheric spacecraft and optically imaging the beam spot in the ionosphere. The magnetospheric spacecraft will carry a steerable electron accelerator, a power-storage system, a plasma contactor, and instruments to measure magnetic and electric fields, plasma, and energetic particles. The spacecraft orbit will be coordinated with a ground-based network of cameras to (a) locate the electron beam spot in the upper atmosphere and (b) monitor the aurora. An overview of the mission concept will be presented, including recent enabling advancements based on (1) a new understanding of the dynamic spacecraft charging of the accelerator and plasma-contactor system in the tenuous magnetosphere based on ion emission rather than electron collection, (2) a new understanding of the propagation properties of pulsed MeV-class beams in the magnetosphere, and (3) the design of a compact high-power 1-MeV electron accelerator and power-storage system. This strategy to (a) determine the magnetosphere-to-ionosphere connections and (b) reduce accelerator- platform charging responds to one of the six emerging-technology needs called out in the most-recent National Academies Decadal Survey for Solar and Space Physics. [LA-UR-17-23614

Photonic Integrated Circuits

NASA Technical Reports Server (NTRS)

Krainak, Michael; Merritt, Scott

2016-01-01

Integrated photonics generally is the integration of multiple lithographically defined photonic and electronic components and devices (e.g. lasers, detectors, waveguides passive structures, modulators, electronic control and optical interconnects) on a single platform with nanometer-scale feature sizes. The development of photonic integrated circuits permits size, weight, power and cost reductions for spacecraft microprocessors, optical communication, processor buses, advanced data processing, and integrated optic science instrument optical systems, subsystems and components. This is particularly critical for small spacecraft platforms. We will give an overview of some NASA applications for integrated photonics.

Spacecraft dielectric surface charging property determination

NASA Technical Reports Server (NTRS)

Williamson, W. S.

1987-01-01

The charging properties of 127 micron thick polyimide, (a commonly used spacecraft dielectric material) was measured under conditions of irradiation by a low-current-density electron beam with energy between 2 and 14 keV. The observed charging characteristics were consistent with predictions of the NASCAP computer model. The use of low electron current density results in a nonlinearity in the sample-potential versus beam-energy characteristic which is attributed to conduction leakage through the sample. Microdischarges were present at relatively low beam energies.

Performance of a flight qualified, thermoelectrically temperature controlled QCM sensor with power supply, thermal controller and signal processor

NASA Technical Reports Server (NTRS)

Wallace, D. A.

1980-01-01

A thermoelectrically temperature controlled quartz crystal microbalance (QCM) system was developed for the measurement of ion thrustor generated mercury contamination on spacecraft. Meaningful flux rate measurements dictated an accurately held sensing crystal temperature despite spacecraft surface temperature variations from -35 C to +60 C over the flight temperature range. An electronic control unit was developed with magentic amplifier transformer secondary power supply, thermal control electronics, crystal temperature analog conditioning and a multiplexed 16 bit frequency encoder.

Electronic switching spherical array antenna

NASA Technical Reports Server (NTRS)

Stockton, R.

1978-01-01

This work was conducted to demonstrate the performance levels attainable with an ESSA (Electronic Switching Spherical Array) antenna by designing and testing an engineering model. The antenna was designed to satisfy general spacecraft environmental requirements and built to provide electronically commandable beam pointing capability throughout a hemisphere. Constant gain and beam shape throughout large volumetric coverage regions are the principle characteristics. The model is intended to be a prototype of a standard communications and data handling antenna for user scientific spacecraft with the Tracking and Data Relay Satellite System (TDRSS). Some additional testing was conducted to determine the feasibility of an integrated TDRSS and GPS (Global Positioning System) antenna system.

Charge Storage, Conductivity and Charge Profiles of Insulators as Related to Spacecraft Charging

NASA Technical Reports Server (NTRS)

Dennison, J. R.; Swaminathan, Prasanna; Frederickson, A. R.

2004-01-01

Dissipation of charges built up near the surface of insulators due to space environment interaction is central to understanding spacecraft charging. Conductivity of insulating materials is key to determine how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. To understand these processes requires knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and charge transport within the insulator, and how the profile of trapped charge affects the transport and emission of charges from insulators. One must consider generation of mobile electrons and holes, their trapping, thermal de-trapping, mobility and recombination. Conductivity is more appropriately measured for spacecraft charging applications as the "decay" of charge deposited on the surface of an insulator, rather than by flow of current across two electrodes around the sample. We have found that conductivity determined from charge storage decay methods is 102 to 104 smaller than values obtained from classical ASTM and IEC methods for a variety of thin film insulating samples. For typical spacecraft charging conditions, classical conductivity predicts decay times on the order of minutes to hours (less than typical orbit periods); however, the higher charge storage conductivities predict decay times on the order of weeks to months leading to accumulation of charge with subsequent orbits. We found experimental evidence that penetration profiles of radiation and light are exceedingly important, and that internal electric fields due to charge profiles and high-field conduction by trapped electrons must be considered for space applications. We have also studied whether the decay constants depend on incident voltage and flux or on internal charge distributions and electric fields; light-activated discharge of surface charge to distinguish among differing charge trapping centers; and radiation-induced conductivity. Our experiments also show that "Malter" electron emission occurs for hours after turning off the electron beam. This Malter emission similar to emission due to negative electron affinity in semiconductors is a result of the prior radiation or optical excitations of valence electrons and their slow drift among traps towards the surface where they are subsequently emitted. This work is supported through funding from the NASA Space Environments and Effects Program.

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.

Risk Management of Microelectronics: The NASA Electronic Parts and Packaging (NEPP) Program

NASA Technical Reports Server (NTRS)

LaBel, Kenneth A.; Sampson, Michael J.

2005-01-01

This viewgraph information provides information on how the NASA Electronic Parts and Packaging (NEPP) Program evaluates the reliability of technologies for Electrical, Electronic, and Electromechanical (EEE) parts, and their suitability for spacecraft applications.

Analysis of the Variation of Energetic Electron Flux with Respect to Longitude and Distance Normal to the Magnetic Equatorial Plane for Galileo Energetic Particle Detector Data

NASA Technical Reports Server (NTRS)

Swimm, Randall; Garrett, Henry B.; Jun, Insoo; Evans, Robin W.

2004-01-01

In this study we examine ten-minute omni-directional averages of energetic electron data measured by the Galileo spacecraft Energetic Particle Detector (EPD). Count rates from electron channels B1, DC2, and DC3 are evaluated using a power law model to yield estimates of the differential electron fluxes from 1 MeV to 11 MeV at distances between 8 and 51 Jupiter radii. Whereas the orbit of the Galileo spacecraft remained close to the rotational equatorial plane of Jupiter, the approximately 11 degree tilt of the magnetic axis of Jupiter relative to its rotational axis allowed the EPD instrument to sample high energy electrons at limited distances normal to the magnetic equatorial plane. We present a Fourier analysis of the semi-diurnal variation of electron fluxes with longitude.

Evaluation of reformulated thermal control coatings in a simulated space environment. Part 1: YB-71

NASA Technical Reports Server (NTRS)

Cerbus, Clifford A.; Carlin, Patrick S.

1994-01-01

The Air Force Space and Missile Systems Center and Wright Laboratory Materials Directorate (WL/ML) have sponsored and effort to effort to reformulate and qualify Illinois Institute of Technology Research Institute (IITRI) spacecraft thermal control coatings. S13G/LO-1, Z93, and YB-71 coatings were reformulated because the potassium silicate binder, Sylvania PS-7, used in the coatings is no longer manufactured. Coatings utilizing the binder's replacement candidate, Kasil 2130, manufactured by The Philadelphia Quartz (PQ) Corporation, Baltimore, Maryland, and undergoing testing at the Materials Directorate's Space Combined Effects Primary Test and Research Equipment (SCEPTRE) Facility operated by the University of Dayton Research Institute (UDRI). The simulated space environment consists of combined ultraviolet (UV) and electron exposure with in site specimen reflectance measurements. A brief description of the effort at IITRI, results and discussion from testing the reformulated YB-71 coating in SCEPTRE, and plans for further testing of reformulated Z93 and S13G/LO-1 are presented.

Integrated Power and Attitude Control Systems for Space Station

NASA Technical Reports Server (NTRS)

Oglevie, R. E.; Eisenhaure, D. B.

1985-01-01

Integrated Power and Attitude Control Systems (IPACS) studies performed over a decade ago established the feasibility of simultaneously storing electrical energy in wheels and utilizing the resulting momentum for spacecraft attitude control. It was shown that such a system possessed many advantages over other contemporary energy storage and attitude control systems in many applications. More recent technology advances in composite rotors, magnetic bearings, and power control electronics have triggered new optimism regarding the feasibility and merits of such a system. The paper presents the results of a recent study whose focus was to define an advanced IPACS and to evaluate its merits for the Space Station application. A system and component design concept is developed to establish the system performance capability. A system level trade study, including life-cycle costing, is performed to define the merits of the system relative to two other candidate systems. It is concluded that an advanced IPACS concept is not only feasible, but offers substantial savings in mass, and life-cycle cost.

Automated bow shock and radiation belt edge identification methods and their application for Cluster, THEMIS/ARTEMIS and Van Allen Probes data

NASA Astrophysics Data System (ADS)

Facsko, Gabor; Sibeck, David; Balogh, Tamas; Kis, Arpad; Wesztergom, Viktor

2017-04-01

The bow shock and the outer rim of the outer radiation belt are detected automatically by our algorithm developed as a part of the Boundary Layer Identification Code Cluster Active Archive project. The radiation belt positions are determined from energized electron measurements working properly onboard all Cluster spacecraft. For bow shock identification we use magnetometer data and, when available, ion plasma instrument data. In addition, electrostatic wave instrument electron density, spacecraft potential measurements and wake indicator auxiliary data are also used so the events can be identified by all Cluster probes in highly redundant way, as the magnetometer and these instruments are still operational in all spacecraft. The capability and performance of the bow shock identification algorithm were tested using known bow shock crossing determined manually from January 29, 2002 to February 3,. The verification enabled 70% of the bow shock crossings to be identified automatically. The method shows high flexibility and it can be applied to observations from various spacecraft. Now these tools have been applied to Time History of Events and Macroscale Interactions during Substorms (THEMIS)/Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) magnetic field, plasma and spacecraft potential observations to identify bow shock crossings; and to Van Allen Probes supra-thermal electron observations to identify the edges of the radiation belt. The outcomes of the algorithms are checked manually and the parameters used to search for bow shock identification are refined.

Integrated Power Source Grant

NASA Technical Reports Server (NTRS)

2001-01-01

Traditional spacecraft power systems incorporate a solar array energy source, an energy storage element (battery), and battery charge control and bus voltage regulation electronics to provide continuous electrical power for spacecraft systems and instruments. Dedicated power conditioning components provide limited fault isolation between systems and instruments, while a centralized power-switching unit provides spacecraft load control. Battery undervoltage conditions are detected by the spacecraft processor, which removes fault conditions and non-critical loads before permanent battery damage can occur. Cost effective operation of a micro-sat constellation requires a fault tolerant spacecraft architecture that minimizes on-orbit operational costs by permitting autonomous reconfiguration in response to unexpected fault conditions. A new micro-sat power system architecture that enhances spacecraft fault tolerance and improves power system survivability by continuously managing the battery charge and discharge processes on a cell-by-cell basis has been developed. This architecture is based on the Integrated Power Source (US patent 5644207), which integrates dual junction solar cells, Lithium Ion battery cells, and processor based charge control electronics into a structural panel that can be deployed or used to form a portion of the outer shell of a micro-spacecraft. The first generation Integrated Power Source is configured as a one inch thick panel in which prismatic Lithium Ion battery cells are arranged in a 3x7 matrix (26VDC) and a 3x1 matrix (3.7VDC) to provide the required output voltages and load currents. A multi-layer structure holds the battery cells, as well as the thermal insulators that are necessary to protect the Lithium Ion battery cells from the extreme temperatures of the solar cell layer. Independent thermal radiators, located on the back of the panel, are dedicated to the solar cell array, the electronics, and the battery cell array. In deployed panel applications, these radiators maintain the battery cells in an appropriate operational temperature range.

NASA requirements and applications environments for electrical power wiring

NASA Technical Reports Server (NTRS)

Stavnes, Mark W.; Hammoud, Ahmad N.

1992-01-01

Serious problems can occur from insulation failures in the wiring harnesses of aerospace vehicles. In most recorded incidents, the failures have been identified to be the result of arc tracking, the propagation of an arc along wiring bundles through degradation of insulation. Propagation of the arc can lead to the loss of the entire wiring harness and the functions which it supports. While an extensive database of testing for arc track resistant wire insulations has been developed for aircraft applications, the counterpart requirements for spacecraft are very limited. The electrical, thermal, mechanical, chemical, and operational requirements for specification and testing of candidate wiring systems for spacecraft applications is presented.

Orbit Maintenance and Navigation of Human Spacecraft at Cislunar Near Rectilinear Halo Orbits

NASA Technical Reports Server (NTRS)

Davis, Diane; Bhatt, Sagar; Howell, Kathleen; Jang, Jiann-Woei; Whitley, Ryan; Clark, Fred; Guzzetti, Davide; Zimovan, Emily; Barton, Gregg

2017-01-01

Multiple studies have concluded that Earth-Moon libration point orbits are attractive candidates for staging operations. The Near Rectilinear Halo Orbit (NRHO), a member of the Earth-Moon halo orbit family, has been singularly demonstrated to meet multi-mission architectural constraints. In this paper, the challenges associated with operating human spacecraft in the NRHO are evaluated. Navigation accuracies and human vehicle process noise effects are applied to various station keeping strategies in order to obtain a reliable orbit maintenance algorithm. Additionally, the ability to absorb missed burns, construct phasing maneuvers to avoid eclipses and conduct rendezvous and proximity operations are examined.

Electron and ion distribution functions in magnetopause reconnection

NASA Astrophysics Data System (ADS)

Wang, S.; Chen, L. J.; Bessho, N.; Hesse, M.; Kistler, L. M.; Torbert, R. B.; Mouikis, C.; Pollock, C. J.

2015-12-01

We investigate electron and ion velocity distribution functions in dayside magnetopause reconnection events observed by the Cluster and MMS spacecraft. The goal is to build a spatial map of electron and ion distribution features to enable the indication of the spacecraft location in the reconnection structure, and to understand plasma energization processes. Distribution functions, together with electromagnetic field structures, plasma densities, and bulk velocities, are organized and compared with particle-in-cell simulation results to indicate the proximities to the reconnection X-line. Anisotropic features in the distributions of magnetospheric- and magnetosheath- origin electrons at different locations in the reconnection inflow and exhaust are identified. In particular, parallel electron heating is observed in both the magnetosheath and magnetosphere inflow regions. Possible effects of the guide field strength, waves, and upstream density and temperature asymmetries on the distribution features will be discussed.

SEPAC data analysis in support of the environmental interaction program

NASA Technical Reports Server (NTRS)

Lin, Chin S.

1990-01-01

Injections of nonrelativistic electron beams from an isolated equipotential conductor into a uniform background of plasma and neutral gas were simulated using a two dimensional electrostatic particle code. The ionization effects of spacecraft charging are examined by including interactions of electrons with neutral gas. The simulations show that the conductor charging potential decreases with increasing neutral background density due to the production of secondary electrons near the conductor surface. In the spacecraft wake, the background electrons accelerated towards the charged space craft produced an enhancement of secondary electrons and ions. Simulations run for longer times indicate that the spacecraft potential is further reduced and short wavelength beam-plasma oscillations appear. The results are applied to explain the space craft charging potential measured during the SEPAC experiments from Spacelab 1. A second paper is presented in which a two dimensional electrostatic particle code was used to study the beam radial expansion of a nonrelativistic electron beam injected from an isolated equipotential conductor into a background plasma. The simulations indicate that the beam radius is generally proportional to the beam electron gyroradius when the conductor is charged to a large potential. The simulations also suggest that the charge buildup at the beam stagnation point causes the beam radial expansion. From a survey of the simulation results, it is found that the ratio of the beam radius to the beam electron gyroradius increases with the square root of beam density and decreases inversely with beam injection velocity. This dependence is explained in terms of the ratio of the beam electron Debye length to the ambient electron Debye length. These results are most applicable to the SEPAC electron beam injection experiments from Spacelab 1, where high charging potential was observed.

An overview of NASA's activities in micro-nano technologies

NASA Technical Reports Server (NTRS)

Stocky, J. F.

2000-01-01

An examination of how mass is used in spacecraft design indicates that technology efforts directed only to reduce the mass of electronics, both digital and analog will not significantly reduce the mass of a spacecraft, regardless of how much success those efforts achieve.

Microwave reflectometer ionization sensor

NASA Technical Reports Server (NTRS)

Seals, Joseph; Fordham, Jeffrey A.; Pauley, Robert G.; Simonutti, Mario D.

1993-01-01

The development of the Microwave Reflectometer Ionization Sensor (MRIS) Instrument for use on the Aeroassist Flight Experiment (AFE) spacecraft is described. The instrument contract was terminated, due to cancellation of the AFE program, subsequent to testing of an engineering development model. The MRIS, a four-frequency reflectometer, was designed for the detection and location of critical electron density levels in spacecraft reentry plasmas. The instrument would sample the relative magnitude and phase of reflected signals at discrete frequency steps across 4 GHz bandwidths centered at four frequencies: 20, 44, 95, and 140 GHz. The sampled data would be stored for later processing to calculate the distance from the spacecraft surface to the critical electron densities versus time. Four stepped PM CW transmitter receivers were located behind the thermal protection system of the spacecraft with horn antennas radiating and receiving through an insulating tile. Techniques were developed to deal with interference, including multiple reflections and resonance effects, resulting from the antenna configuration and operating environment.

Radio range measurements of coronal electron densities at 13 and 3.6 centimeter wavelengths during the 1988 solar conjunction of Voyager 2

NASA Technical Reports Server (NTRS)

Krisher, T. P.; Anderson, J. D.; Morabito, D. D.; Asmar, S. W.; Borutzki, S. E.; Delitsky, M. L.; Densmore, A. C.; Eshe, P. M.; Lewis, G. D.; Maurer, M. J.

1991-01-01

Radio range measurements of total solar plasma delay obtained during the solar conjunction of the Voyager 2 spacecraft in December 1988, which occurred near solar maximum activity in the 11 yr cycle are reported. The radio range measurements were generated by the Deep Space Network at two wavelengths on the downlink from the spacecraft: 3.6 and 13 cm. A direct measurement of the integrated electron density along the ray path between the earth stations and the spacecraft was obtained by differencing the range at the two wavelengths. Coronal electron density profiles have been derived during ingress and egress of the ray path, which approached the sun to within 5 solar radii. At 10 solar radii, the derived density profiles yield 34079 + or - 611/cu cm on ingress and 49688 + or - 983/cu cm on egress. These density levels are significantly higher than observed near previous solar maxima.

Space Environmental Effects Testing and Characterization of the Candidate Solar Sail Material Aluminized Mylar

NASA Technical Reports Server (NTRS)

Edwards, D. L.; Hubbs, W. S.; Wertz, G. E.; Alstatt, R.; Munafo, Paul (Technical Monitor)

2001-01-01

The usage of solar sails as a propellantless propulsion system has been proposed for many years. The technical challenges associated with solar sails are fabrication of ultralightweight films, deploying the sails and controlling the spacecraft. Integral to all these challenges is the mechanical property integrity of the sail while exposed to the harsh environment of space. This paper describes testing and characterization of a candidate solar sail material, Aluminized Mylar. This material was exposed to a simulated Geosynchronous Transfer Orbit (GTO) and evaluated by measuring thermooptical and mechanical property changes. Testing procedures and results are presented.

Space physics missions handbook

NASA Technical Reports Server (NTRS)

Cooper, Robert A. (Compiler); Burks, David H. (Compiler); Hayne, Julie A. (Editor)

1991-01-01

The purpose of this handbook is to provide background data on current, approved, and planned missions, including a summary of the recommended candidate future missions. Topics include the space physics mission plan, operational spacecraft, and details of such approved missions as the Tethered Satellite System, the Solar and Heliospheric Observatory, and the Atmospheric Laboratory for Applications and Science.

Cartography and Information Systems for the Luna-Glob Landing Sites

NASA Astrophysics Data System (ADS)

Kokhanov, A.; Karachevtseva, I.; Oberst, J.; Zubarev, A.; Robinson, M. S.

2012-09-01

We provide cartography and information system support to the LUNA-GLOB mission and assess candidate landing sites [1] on the basis of different available remote sensing data sets. The main goal of our work is to identify science opportunities in the sub-polar areas and to detect possible hazards for any landing spacecraft.

Design and material selection for inverter transformer cores

NASA Technical Reports Server (NTRS)

Mclyman, W. T.

1973-01-01

Report is announced which studied magnetic properties of candidate materials for use in spacecraft transformers, static inverters, converters, and transformer-rectifier power supplies. Included are material characteristics for available alloy compositions in tabular form, including: trade names, saturated flux density, dc coercive force, loop squareness, material density, and watts per pound at 3 KHz.

New Insight into Short-Wavelength Solar Wind Fluctuations from Vlasov Theory

NASA Technical Reports Server (NTRS)

Sahraoui, Fouad; Belmont, G.; Goldstein, M. L.

2012-01-01

The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations gave evidence of the dominance of kinetic Alfven waves (KAWs) at sub-ion scales with omega < omega(sub ci), other studies suggest that the KAW mode cannot carry the turbulence cascade down to electron scales and that the whistler mode (i.e., omega > omega (sub ci)) is more relevant. Here, we study key properties of the short-wavelength plasma modes under limited, but realistic, SW conditions, Typically Beta(sub i) approx. > Beta (sub e) 1 and for high oblique angles of propagation 80 deg <= Theta (sub kB) < 90 deg as observed from the Cluster spacecraft data. The linear properties of the plasma modes under these conditions are poorly known, which contrasts with the well-documented cold plasma limit and/or moderate oblique angles of propagation (Theta (sub kB) < 80 deg). Based on linear solutions of the Vlasov kinetic theory, we discuss the relevance of each plasma mode (fast, Bernstein, KAW, whistler) in carrying the energy cascade down to electron scales. We show, in particular, that the shear Alfven mode (known in the magnetohydrodynamic limit) extends at scales kappa rho (sub i) approx. > 1 to frequencies either larger or smaller than omega (sub ci), depending on the anisotropy kappa (parallel )/ kappa(perpendicular). This extension into small scales is more readily called whistler (omega > omega (sub ci)) or KAW (omega < omega (sub ci)) although the mode is essentially the same. This contrasts with the well-accepted idea that the whistler branch always develops as a continuation at high frequencies of the fast magnetosonic mode. We show, furthermore, that the whistler branch is more damped than the KAW one, which makes the latter the more relevant candidate to carry the energy cascade down to electron scales. We discuss how these new findings may facilitate resolution of the controversy concerning the nature of the small-scale turbulence, and we discuss the implications for present and future spacecraft wave measurements in the SW.

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Technical Reports Server (NTRS)

Barrie, A.; Adrian, Mark L.; Yeh, P.-S.; Winkert, G. E.; Lobell, J. V.; Vinas, A.F.; Simpson, D. J.; Moore, T. E.

2008-01-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eights (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 deg x 180 deg fields-of-view (FOV) are set 90 deg apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 deg x 180 deg fan about its nominal viewing (0 deg deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the results in the DES complement of a given spacecraft generating 6.5-Mbs(exp -1) of electron data while the DIS generates 1.1-Mbs(exp -1) of ion data yielding an FPI total data rate of 6.6-MBs(exp -1). The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mbs(exp -1). Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements. Topics to be discussed include: review of compression algorithm; data quality; data formatting/organization; and, implications for data/matrix pruning. To conclude a presentation of the base-lined FPI data compression approach is provided.

Observations and Simulations of Electron Dynamics Near an Active Neutral Line

NASA Technical Reports Server (NTRS)

Goldstein, M. L.; Hwang, Kyoung-Joo; Ashour-Abdalla, Maha; El-Aloui, Mostafa; Schriver, David; Richard, Robert; Zhou, Meng; Walker, Ray

2010-01-01

Recent observations in the Earth's magnetotail have shown rapid increases in the fluxes of energetic electrons with energies up to 100's of keV associated with dipolarization fronts that propagate into the inner magnetosphere. On August 15, 2001 the four Cluster spacecraft located slightly dawnward of midnight (yGSM approx. -5.4RE) at xGSM approx. -18RE observed a series of earthward propagating dipolarization fronts [Hwang et al., 2010]. At least 6 dipolarization fronts were observed in a 20m interval. Unlike previously reported cases the fluxes of electrons up to 95keV decreased during the passage of the first three fronts over the spacecraft. The energetic electron fluxes increased during the passage of the last three fronts. We have performed a global magnetohydrodynamic simulation of this event using solar wind observations from the ACE satellite to drive the simulation. In the simulation a very complex reconnection system in the near-Earth tail at XGSM approx. -20RE launched a series of earthward propagating dipolarization fronts that are similar to those observed on Cluster. The simulation results indicate that the Cluster spacecraft were just earthward of the reconnection site. In this paper we will present a study of the dynamics of electrons associated with these events by using the large-scale kinetic simulation approach in which we launch a large number of electrons into the electric and magnetic fields from this simulation.

Space environmental effects on spacecraft: LEO materials selection guide, part 2

NASA Astrophysics Data System (ADS)

Silverman, Edward M.

1995-08-01

This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 2 covers thermal control systems, power systems, optical components, electronic systems, and applications.

Space environmental effects on spacecraft: LEO materials selection guide, part 2

NASA Technical Reports Server (NTRS)

Silverman, Edward M.

1995-01-01

This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 2 covers thermal control systems, power systems, optical components, electronic systems, and applications.

Evidence of large empty lava tubes on the Moon using GRAIL gravity

NASA Astrophysics Data System (ADS)

Chappaz, Loic; Sood, Rohan; Melosh, Henry J.; Howell, Kathleen C.; Blair, David M.; Milbury, Colleen; Zuber, Maria T.

2017-01-01

NASA's GRAIL mission employed twin spacecraft in polar orbits around the Moon to measure the lunar gravity field at unprecedentedly high accuracy and resolution. The low spacecraft altitude in the extended mission enables the detection of small-scale surface or subsurface features. We analyzed these data for evidence of empty lava tubes beneath the lunar maria. We developed two methods, gradiometry and cross correlation, to isolate the target signal of long, narrow, sinuous mass deficits from a host of other features present in the GRAIL data. Here we report the discovery of several strong candidates that are either extensions of known lunar rilles, collocated with the recently discovered "skylight" caverns, or underlying otherwise unremarkable surfaces. Owing to the spacecraft polar orbits, our techniques are most sensitive to east-west trending near-surface structures and empty lava tubes with minimum widths of several kilometers, heights of hundreds of meters, and lengths of tens of kilometers.

A space debris simulation facility for spacecraft materials evaluation

NASA Technical Reports Server (NTRS)

Taylor, Roy A.

1987-01-01

A facility to simulate the effects of space debris striking an orbiting spacecraft is described. This facility was purchased in 1965 to be used as a micrometeoroid simulation facility. Conversion to a Space Debris Simulation Facility began in July 1984 and it was placed in operation in February 1985. The facility consists of a light gas gun with a 12.7-mm launch tube capable of launching 2.5-12.7 mm projectiles with a mass of 4-300 mg and velocities of 2-8 km/sec, and three target tanks of 0.067 m, 0.53 a m and 28.5 a m. Projectile velocity measurements are accomplished via pulsed X-ray, laser diode detectors, and a Hall photographic station. This facility is being used to test development structural configurations and candidate materials for long duration orbital spacecraft. A summary of test results are also described.

Voyager spacecraft electrostatic discharge testing

NASA Technical Reports Server (NTRS)

Whittlesey, A.; Inouye, G.

1980-01-01

The program of environmental testing undergone by the Voyager spacecraft in order to simulate the transient voltage effects of electrostatic discharges expected in the energetic plasma environment of Jupiter is reported. The testing consists of studies of the electrostatic discharge characteristics of spacecraft dielectrics in a vacuum-chamber-electron beam facility, brief piece part sensitivity tests on such items as a MOSFET multiplexer and the grounding of the thermal blanket, and assembly tests of the magnetometer boom and the science boom. In addition, testing of a complete spacecraft was performed using two arc sources to simulate long and short duration discharge sources for successive spacecraft shielding and grounding improvements. Due to the testing program, both Voyager 1 and Voyager 2 experienced tolerable electrostatic discharge-caused transient anomalies in science and engineering subsystems, however, a closer duplication of the spacecraft environment is necessary to predict and design actual spacecraft responses more accurately.

A New Technique using Electron Velocity Data from the Four Cluster Spacecraft to Explore Magnetofluid Turbulence in the Solar Wind

NASA Technical Reports Server (NTRS)

Goldstein, Melvyn L.; Gurgiolo, C.; Fazakerley, A.; Lahiff, A.

2008-01-01

It is now possible in certain circumstances to use velocity moments computed from the Plasma Electron and Current Experiment (PEACE) on the four Cluster spacecraft to determine a number of turbulence properties of the solar wind, including direct measurements of the vorticity and compressibility. Assuming that the four spacecraft are not co-planar and that there is only a linear variation of the plasma variables across the volume defined by the four satellites, one can estimate the curl of the fluid velocity, i.e., the vorticity. From the vorticity it is possible to explore directly intermittent regions in the solar wind where dissipation is likely to be enhanced. In addition, one can estimate directly the Taylor microscale.

Surface Charging in the Auroral Zone on the DMSP Spacecraft in LEO

NASA Astrophysics Data System (ADS)

Anderson, Phillip C.

1998-11-01

A recent anomaly on the DMSP F13 spacecraft was attributed to an electrical malfunction caused by an electrostatic discharge on the vehicle associated with surface charging. It occurred during an intense energetic electron precipitation event (an auroral arc) within a region of very low plasma density in the auroral zone. A study of 1.5 year's worth of DMSP data from three satellites acquired during the recent minimum in the solar cycle has shown that such charging was a common occurrence with 704 charging events found. This is the result of significantly reduced background plasma densities associated with the solar minimum; smaller than ever previously experienced by the DMSP spacecraft. At times, the spacecraft charged for periods of 10s of seconds as they skimmed along an auroral arc instead of cutting across it. We show examples of the observed plasma density and the precipitating electron and ion spectra associated with the charging, and the MLT distribution and the seasonal distribution of the events. The preponderance of events occurred in the premidnight and morning sectors with two types of electron spectra being observed: a sharply peaked distribution indicative of field-aligned acceleration in the premidnight sector and a very hard distribution in the morning sector.

Notes on the diversity of the properties of radio bursts observed on the nightside of Venus

NASA Technical Reports Server (NTRS)

Sonwalkar, Vikas S.; Carpenter, D. L.

1995-01-01

We report on further studies of radio wave bursts detected by the Orbiting Electric Field Detector (OEFD) on the Pioneer Venus Orbiter (PVO) in the nightside ionosphere of Venus. We have tested a total of 25 cases of wave burst activity for evidence of whistler-mode propagation to the spacecraft from impulsive subionospheric sources. As in a previous study of 11 of these cases (Sonwalkar et al., 1991) we find at least two distinct classes of events, one, mostly involving bursts at 100 Hz only, that passes certain tests for whistler-mode propagation, and another, mostly involving bursts in two or more of the four PVO narrowband channels (at 100 Hz, 730 Hz, 5.4 kHz, and 30 kHz), that fails to pass the tests. The subionospheric lightning hypothesis continues to be tenable as a candidate explanation for many of the 100 Hz-only events, but its number of 100 Hz-only cases that do no pass all the applicable whistler-mode tests, as well as the existence at a wide range of altitudes of multichannel cases that are clearly not propagating whistler-mode waves. The wideband bursts are often observed at altitudes above 1000 km and frequently occur in regions of locally reduced electron density. Those observed at high altitude (and possibly low altitude as well) are believed to be generated near the spacecraft, possibly by an as yet unknown mechanism responsible for similar burst observations made near Earth and other planets.

The Physics of Solar Sails

NASA Technical Reports Server (NTRS)

Hollerman, William Andrew

2003-01-01

The concept of using photon pressure for propulsion has been considered since Tsiolkovsky in 1921. In fact, Tsiolkovsky and Tsander wrote of 'using tremendous mirrors of very thin sheets' and 'using the pressure of sunlight to attain cosmic velocities' in 1924. The term 'solar sailing' was coined in the late 1950s and was popularized by Arthur C. Clarke in the short story Sunjammer (The Wind From the Sun) in May 1964. The National Aeronautics and Space Administration (NASA) used sailing techniques to extend the operational life of the Mariner 10 spacecraft in 1974-1975. A problem in the control system was causing Mariner 10 to go off course. By controlling the attitude of Mariner 10 and the angle of the solar power panels relative to the Sun, ground controllers were able to correct the problem without using precious fuel. Once thought to be difficult or impossible, solar sailing has come out of science fiction and into the realm of possibility. Any spacecraft using this method would need to deploy a thin sail that could be as large as many kilometers in extent. Candidate sail materials should be: 1) strong, 2) ultra-lightweight (density of a few g/sq m), 3) able to be folded or crushed until deployed, 4) subject to minimal sagging or stretching, and 5) resistant to ionizing radiation, such as galactic and solar particles (electrons and protons), x-rays, ultraviolet light, and magnetically trapped charged particles. Solar sails must be resistant to each of these types of radiation.

Direct comparison of Viking 2.3-GHz signal phase fluctuation and columnar electron density between 2 and 160 solar radii

NASA Technical Reports Server (NTRS)

Berman, A. L.; Wackley, J. A.; Hietzke, W. H.

1982-01-01

The relationship between solar wind induced signal phase fluctuation and solar wind columnar electron density has been the subject of intensive analysis during the last two decades. In this article, a sizeable volume of 2.3-GHz signal phase fluctuation and columnar electron density measurements separately and concurrently inferred from Viking spacecraft signals are compared as a function of solar geometry. These data demonstrate that signal phase fluctuation and columnar electron density are proportional over a very wide span of solar elongation angle. A radially dependent electron density model which provides a good fit to the columnar electron density measurements and, when appropriately scaled, to the signal phase fluctuation measurements, is given. This model is also in good agreement with K-coronameter observations at 2 solar radii (2r0), with pulsar time delay measurements at 10r0, and with spacecraft in situ electron density measurements at 1 AU.

Simultaneous Measurements of Substorm-Related Electron Energization in the Ionosphere and the Plasma Sheet

NASA Astrophysics Data System (ADS)

Sivadas, N.; Semeter, J.; Nishimura, Y.; Kero, A.

2017-10-01

On 26 March 2008, simultaneous measurements of a large substorm were made using the Poker Flat Incoherent Scatter Radar, Time History of Events and Macroscale Interactions during Substorm (THEMIS) spacecraft, and all sky cameras. After the onset, electron precipitation reached energies ≳100 keV leading to intense D region ionization. Identifying the source of energetic precipitation has been a challenge because of lack of quantitative and magnetically conjugate measurements of loss cone electrons. In this study, we use the maximum entropy inversion technique to invert altitude profiles of ionization measured by the radar to estimate the loss cone energy spectra of primary electrons. By comparing them with magnetically conjugate measurements from THEMIS-D spacecraft in the nightside plasma sheet, we constrain the source location and acceleration mechanism of precipitating electrons of different energy ranges. Our analysis suggests that the observed electrons ≳100 keV are a result of pitch angle scattering of electrons originating from or tailward of the inner plasma sheet at 9RE, possibly through interaction with electromagnetic ion cyclotron waves. The electrons of energy 10-100 keV are produced by pitch angle scattering due to a potential drop of ≲10 kV in the auroral acceleration region (AAR) as well as wave-particle interactions in and tailward of the AAR. This work demonstrates the utility of magnetically conjugate ground- and space-based measurements in constraining the source of energetic electron precipitation. Unlike in situ spacecraft measurements, ground-based incoherent scatter radars combined with an appropriate inversion technique can be used to provide remote and continuous-time estimates of loss cone electrons in the plasma sheet.

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

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

The Kepler End-to-End Data Pipeline: From Photons to Far Away Worlds

NASA Technical Reports Server (NTRS)

Cooke, Brian; Thompson, Richard; Standley, Shaun

2012-01-01

Launched by NASA on 6 March 2009, the Kepler Mission has been observing more than 100,000 targets in a single patch of sky between the constellations Cygnus and Lyra almost continuously for the last two years looking for planetary systems using the transit method. As of October 2011, the Kepler spacecraft has collected and returned to Earth just over 290 GB of data, identifying 1235 planet candidates with 25 of these candidates confirmed as planets via ground observation. Extracting the telltale signature of a planetary system from stellar photometry where valid signal transients can be small as a 40 ppm is a difficult and exacting task. The end-to end processing of determining planetary candidates from noisy, raw photometric measurements is discussed.

Magnetoresistive Current Sensors for High Accuracy, High Bandwidth Current Measurement in Spacecraft Power Electronics

NASA Astrophysics Data System (ADS)

Slatter, Rolf; Goffin, Benoit

2014-08-01

The usage of magnetoresistive (MR) current sensors is increasing steadily in the field of power electronics. Current sensors must not only be accurate and dynamic, but must also be compact and robust. The MR effect is the basis for current sensors with a unique combination of precision and bandwidth in a compact package. A space-qualifiable magnetoresistive current sensor with high accuracy and high bandwidth is being jointly developed by the sensor manufacturer Sensitec and the spacecraft power electronics supplier Thales Alenia Space (T AS) Belgium. Test results for breadboards incorporating commercial-off-the-shelf (COTS) sensors are presented as well as an application example in the electronic control and power unit for the thrust vector actuators of the Ariane5-ME launcher.

Status of Galileo interim radiation electron model

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

Results from the first flight of the Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket

NASA Astrophysics Data System (ADS)

Glesener, Lindsay; Christe, S.; Ishikawa, S.; Ramsey, B.; Takahashi, T.; Watanabe, S.; Saito, S.; Lin, R. P.; Krucker, S.; FOXSI Team

2013-07-01

Understanding electron acceleration in solar flares requires X-ray studies with greater sensitivity and dynamic range than are available with current solar hard X-ray observers (i.e. the RHESSI spacecraft). RHESSI employs an indirect Fourier imaging method that is intrinsically limited in dynamic range and therefore can rarely image faint coronal flare sources in the presence of bright footpoints. With greater sensitivity and dynamic range, electron acceleration sites in the corona could be studied in great detail. Both these capabilities can be advanced by the use of direct focusing optics. The recently flown Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload demonstrates the feasibility and usefulness of hard X-ray focusing optics for solar study. FOXSI features grazing-incidence replicated nickel optics from the NASA Marshall Space Flight Center and fine-pitch silicon strip detectors developed by the Astro-H team at JAXA/ISAS. FOXSI flew successfully on November 2, 2012, producing images and spectra of a microflare and performing a search for nonthermal emission (4-15 keV) from nanoflares in the quiet Sun. Nanoflares are a candidate for providing the required energy to heat the solar corona to its high temperature of a few million degrees. A future satellite version of FOXSI, featuring similar optics and detectors, could make detailed observations of hard X-rays from flare-accelerated electrons, identifying and characterizing particle acceleration sites and mapping out paths of energetic electrons as they leave these sites and propagate throughout the solar corona.

Identification of Possible Interstellar Dust Impact Craters on Stardust Foil I033N,1

NASA Astrophysics Data System (ADS)

Ansari, A.; ISPE Team; 29,000 Stardust@home Dusters

2011-12-01

The Interstellar Dust Collector onboard NASA's Stardust Mission - the first to return solid extraterrestrial material to Earth from beyond the Moon - was exposed to the interstellar dust stream for a total of 229 days prior to the spacecraft's return in 2006 [1]. Aluminum foils and aerogel tiles on the collector may have captured the first samples of contemporary interstellar dust. Interstellar Preliminary Examination (ISPE) focuses in part on crater identification and analysis of residue within the craters to determine the nature and origin of the impacting particles. Thus far, ISPE has focused on nine foils and found a total of 20 craters. The number density of impact craters on the foils exceeds by far estimates made from interstellar flux calculations [2]. To identify craters, foil I1033N,1 was scanned with the Field Museum's Evo 60 Scanning Electron Microscope (SEM) at a resolution of 52 nm/pixel with a 15 kV and 170-240 pA beam. Contamination was monitored according to the ISPE protocol: four 4 μm × 3 μm areas of C layers of different thicknesses on a Stardust-type Al foil were irradiated 20 times for 50 s each, while the C and Al signals were recorded with energy-dispersive X-ray spectroscopy (EDS). The C/Al ratio did not increase after 20 repetitions on each of the four areas. The same experiment repeated 7 months later yielded identical results. Thus, analysis with the SEM results in no detectable contamination. Crater candidates were manually selected from SEM images, then reimaged at higher resolution (17 nm/pixel) in order to eliminate false detections. The foil was then sent to Washington University for Auger Nanoprobe elemental analysis of crater 11_175 (diam. 1.1 μm), and to the Naval Research Laboratory for focused ion beam work and transmission electron microscopy and EDS. Twelve crater candidates (diam. 0.28 - 1.1 μm), both elliptical and circular, were identified. The number density of craters on foil 1033N is 15.8 cm^-2. Auger measurements of crater 11_175 revealed the presence of C, O, Al, Si, a small amount of Na, and possibly Ce and Zn [3] - both components of solar cell cover glass - indicating that this particular crater resulted from a particle that impacted the spacecraft's solar panels. TEM/EDS analysis determined the presence of solar cell glass.

The Plasma Environment at Enceladus and Europa Compared

NASA Astrophysics Data System (ADS)

Rymer, Abigail; Persoon, Ann; Morooka, Michiko; Heuer, Steven; Westlake, Joseph H.

2017-10-01

The plasma environment near Enceladus is complex, as revealed during 16 encounters of the Cassini spacecraft. The well documented Enceladus plumes create a dusty, asymmetric exosphere in which electrons can attach to small ice particles - forming anions, and negatively charged nanograins and dust - to the extent that cations can be the lightest charged particles present and, as a result, the dominant current carriers. Several instruments on the Cassini spacecraft are able to measure this environment in both expected and unexpected ways. Cassini Plasma Spectrometer (CAPS) is designed and calibrated to measure the thermal plasma ions and electrons and also measures the energy/charge of charged nanograins when present. Cassini Radio Plasma Wave Sensor (RPWS) measures electron density as derived from the ‘upper hybrid frequency’ which is a function of the total free electron density and magnetic field strength and provides a vital ground truth measurement for Cassini calibration when the density is sufficiently high for it to be well measured. Cassini Langmuir Probe (LP) measures the electron density and temperature via direct current measurement, and both CAPS and LP can provide estimates for the spacecraft potential which we compare. The plasma environment near Europa is similarly complex and, although not so comprehensively equipped and hampered by the non-deployment of its high gain antenna, the Galileo spacecraft made similar measurements during 9 Europa flybys and recent observations have suggested that, like Enceladus, Europa might have active plume activity. We present a detailed comparison of data from the Cassini and Galileo sensors in order to assess the plasma environment observed by the different instruments, discuss what is consistent and otherwise, and the implications for the plasma environment at Enceladus and Europa in the context of work to date as well as implications for future studies.

Two Phase Technology Development Initiatives

NASA Technical Reports Server (NTRS)

Didion, Jeffrey R.

1999-01-01

Three promising thermal technology development initiatives, vapor compression thermal control system, electronics cooling, and electrohydrodynamics applications are outlined herein. These technologies will provide thermal engineers with additional tools to meet the thermal challenges presented by increased power densities and reduced architectural options that will be available in future spacecraft. Goddard Space Flight Center and the University of Maryland are fabricating and testing a 'proto- flight' vapor compression based thermal control system for the Ultra Long Duration Balloon (ULDB) Program. The vapor compression system will be capable of transporting approximately 400 W of heat while providing a temperature lift of 60C. The system is constructed of 'commercial off-the-shelf' hardware that is modified to meet the unique environmental requirements of the ULDB. A demonstration flight is planned for 1999 or early 2000. Goddard Space Flight Center has embarked upon a multi-discipline effort to address a number of design issues regarding spacecraft electronics. The program addressed the high priority design issues concerning the total mass of standard spacecraft electronics enclosures and the impact of design changes on thermal performance. This presentation reviews the pertinent results of the Lightweight Electronics Enclosure Program. Electronics cooling is a growing challenge to thermal engineers due to increasing power densities and spacecraft architecture. The space-flight qualification program and preliminary results of thermal performance tests of copper-water heat pipes are presented. Electrohydrodynamics (EHD) is an emerging technology that uses the secondary forces that result from the application of an electric field to a flowing fluid to enhance heat transfer and manage fluid flow. A brief review of current EHD capabilities regarding heat transfer enhancement of commercial heat exchangers and capillary pumped loops is presented. Goddard Space Flight Center research efforts applying this technique to fluid management and fluid pumping are discussed.

Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

NASA Technical Reports Server (NTRS)

Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

1972-01-01

With missions to Jupiter, the spacecraft will be exposed for extended duration to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine sporeforming and three nonsporeforming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2-, 12-, and 25-MeV electrons at different doses with simultaneous exposure to a vacuum of 0.0013 N/sqm at 20 and -20 C. The radioresistance of the subpopulation was dependent on the isolate, dose, and energy of electrons. Temperature affected the radioresistance of only the sporeforming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J/kg, while nonsporeforming isolates (micrococci) were reduced 1.5 to 2 logs/1500 J/kg with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons.

Power requirements for commercial communications spacecraft

NASA Technical Reports Server (NTRS)

Billerbeck, W. J.

1985-01-01

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

Spacecraft Charging Issues for Launch Vehicles

NASA Technical Reports Server (NTRS)

Buhler, Janessa L.; Minow, Joseph I.; Trout, Dawn H.

2014-01-01

Spacecraft charging is well known threat to successful long term spacecraft operations and instrument reliability in orbits that spend significant time in hot electron environments. In recent years, spacecraft charging has increasingly been recognized as a potentially significant engineering issue for launch vehicles used to deploy spacecraft using (a) low Earth orbit (LEO), high inclination flight trajectories that pass through the auroral zone, (b) geostationary transfer orbits that require exposures to the hot electron environments in the Earths outer radiation belts, and (c) LEO escape trajectories using multiple phasing orbits through the Earths radiation belts while raising apogee towards a final Earth escape geometry. Charging becomes an issue when significant areas of exposed insulating materials or ungrounded conductors are used in the launch vehicle design or the payload is designed for use in a benign charging region beyond the Earths magnetosphere but must survive passage through the strong charging regimes of the Earths radiation belts. This presentation will first outline the charging risks encountered on typical launch trajectories used to deploy spacecraft into Earth orbit and Earth escape trajectories. We then describe the process used by NASAs Launch Services Program to evaluate when surface and internal charging is a potential risk to a NASA mission. Finally, we describe the options for mitigating charging risks including modification of the launch vehicle andor payload design and controlling the risk through operational launch constraints to avoid significant charging environments.

Cluster Inter-Spacecraft Communications

NASA Technical Reports Server (NTRS)

Cox, Brian

2008-01-01

A document describes a radio communication system being developed for exchanging data and sharing data-processing capabilities among spacecraft flying in formation. The system would establish a high-speed, low-latency, deterministic loop communication path connecting all the spacecraft in a cluster. The system would be a wireless version of a ring bus that complies with the Institute of Electrical and Electronics Engineers (IEEE) standard 1393 (which pertains to a spaceborne fiber-optic data bus enhancement to the IEEE standard developed at NASA's Jet Propulsion Laboratory). Every spacecraft in the cluster would be equipped with a ring-bus radio transceiver. The identity of a spacecraft would be established upon connection into the ring bus, and the spacecraft could be at any location in the ring communication sequence. In the event of failure of a spacecraft, the ring bus would reconfigure itself, bypassing a failed spacecraft. Similarly, the ring bus would reconfigure itself to accommodate a spacecraft newly added to the cluster or newly enabled or re-enabled. Thus, the ring bus would be scalable and robust. Reliability could be increased by launching, into the cluster, spare spacecraft to be activated in the event of failure of other spacecraft.

Characterization of spacecraft and environmental disturbances on a SmallSat

NASA Technical Reports Server (NTRS)

Johnson, Thomas A.; Nguyen, Dung Phu Chi; Cuda, Vince; Freesland, Doug

1994-01-01

The objective of this study is to model the on-orbit vibration environment encountered by a SmallSat. Vibration control issues are common to the Earth observing, imaging, and microgravity communities. A spacecraft may contain dozens of support systems and instruments each a potential source of vibration. The quality of payload data depends on constraining vibration so that parasitic disturbances do not affect the payload's pointing or microgravity requirement. In practice, payloads are designed incorporating existing flight hardware in many cases with nonspecific vibration performance. Thus, for the development of a payload, designers require a thorough knowledge of existing mechanical devices and their associated disturbance levels. This study evaluates a SmallSat mission and seeks to answer basic questions concerning on-orbit vibration. Payloads were considered from the Earth observing, microgravity, and imaging communities. Candidate payload requirements were matched to spacecraft bus resources of present day SmallSats. From the set of candidate payloads, the representative payload GLAS (Geoscience Laser Altimeter System) was selected. The requirements of GLAS were considered very stringent for the 150 - 500 kg class of payloads. Once the payload was selected, a generic SmallSat was designed in order to accommodate the payload requirements (weight, size, power, etc.). This study seeks to characterize the on-orbit vibration environment of a SmallSat designed for this type of mission and to determine whether a SmallSat can provide the precision pointing and jitter control required for earth observing payloads.

Active control of spacecraft potentials at geosynchronous orbit

NASA Technical Reports Server (NTRS)

Goldstein, R.; Deforest, S. E.

1976-01-01

Tests have been conducted concerning the active control of the potentials of the geosynchronous satellites ATS-5 and ATS-6. The ATS-5 tests show that a simple electron emitter can be used to reduce the magnitude of the potential of a spacecraft which has been charged negatively by the environment. The ATS-6 ion thruster had also a pronounced effect on the potential barrier. In this case, the flux of high-energy primary ions and of low-charge exchange ions produces a space-charge neutralization effect which the electron gun alone cannot achieve.

Plasma Waves Associated with Energetic Particles Streaming into the Solar Wind from the Earth’s Bow Shock.

DTIC Science & Technology

1980-12-08

when the magnetic field changed in such a way that the ISEE spacecraft were brought into the ion foreshock region. The lower panels of Figures 1 and 2...electrons in the absence of ions usually occurs when the spacecraft is downstream from the electron foreshock boundary but upstream of the ion... foreshock boundary. Two well-defined upstream ion events occur in the following hour as shown in Figure 5. The top panel shows that a moderately intense ion

On the Utilization of In-flight Radiation-induced Performance Data and Anomaly Resolution of Commercial Off the Shelf (COTS) Electronics

NASA Technical Reports Server (NTRS)

LeBel, Kenneth A.; Poivey, Christian; Barth, Janet L.

2003-01-01

This viewgraph presentation presents an overview of the use of in-flight science data to review the radiation effects on commercial off the shelf (COTS) electronics used in recent spacecraft missions. The authors review the hazards that the space radiation environment pose for spacecraft electronics. They specifically discuss long term effects such as total ionizing dose (TID) and short term effects like single particle events (SEE). The advantages of using COTS electronics despite not being radiation hardened are mentioned. The reasons cite for tracking in-flight performance of COTS electronics include: anomaly resolution, validate ground tests and environmental predictions and provide lessons for future designers. Sample radiation impacts of science data from the following missions are analyzed: SOHO/LASCO 3 Coronograph, Microwave Anisotrophy Probe, Hubble Space Telescope and Chandra X-Ray Observatory.

Electron plasma oscillations in the Venus foreshock

NASA Technical Reports Server (NTRS)

Crawford, G. K.; Strangeway, R. J.; Russell, C. T.

1990-01-01

Plasma waves are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These wave signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. The electron foreshock boundary is clearly evident in the data as a sharp onset in wave activity and a peak in intensity. Wave intensity is seen to drop rapidly with increasing penetration into the foreshock. The peak wave electric field strength at the electron foreshock boundary is found to be similar to terrestrial observations. A normalized wave spectrum was constructed using measurements of the electron plasma frequency and the spectrum was found to be centered about this value. These results, along with polarization studies showing the wave electric field to be field aligned, are consistent with the interpretation of the waves as electron plasma oscillations.

Modeling, Analysis, and Interpretation of Photoelectron Energy Spectra at Enceladus Observed by Cassini

NASA Astrophysics Data System (ADS)

Taylor, S. A.; Coates, A. J.; Jones, G. H.; Wellbrock, A.; Fazakerley, A. N.; Desai, R. T.; Caro-Carretero, R.; Michiko, M. W.; Schippers, P.; Waite, J. H.

2018-01-01

The Electron Spectrometer (ELS) of the Cassini Plasma Spectrometer has observed photoelectrons produced in the plume of Enceladus. These photoelectrons are observed during Enceladus encounters in the energetic particle shadow where the spacecraft is largely shielded from penetrating radiation by the moon. We present a complex electron spectrum at Enceladus including evidence of two previously unidentified electron populations at 6-10 eV and 10-16 eV. We estimate that the proportion of "hot" (>15 eV) to "cold" (<15 eV) electrons during the Enceladus flybys is ≈ 0.1-0.5%. We have constructed a model of photoelectron production in the plume and compared it with ELS Enceladus flyby data by scaling and energy shifting according to spacecraft potential. We suggest that the complex structure of the electron spectrum observed can be explained entirely by photoelectron production in the plume ionosphere.

Near-Earth Space Radiation Models

NASA Technical Reports Server (NTRS)

Xapsos, Michael A.; O'Neill, Patrick M.; O'Brien, T. Paul

2012-01-01

Review of models of the near-Earth space radiation environment is presented, including recent developments in trapped proton and electron, galactic cosmic ray and solar particle event models geared toward spacecraft electronics applications.

Cost-Effective NEO Characterization Using Solar Electric Propulsion (SEP)

NASA Astrophysics Data System (ADS)

Dissly, R. W.; Reinert, R.; Mitchell, S.

2003-05-01

We present a cost-effective multiple NEO rendezvous mission design optimized around the capabilities of Ball's 200-kg NEOX Solar Electric Propelled microsatellite. The NEOX spacecraft is 3-axis stabilized with better-than 1 milliradian pointing accuracy to serve as an excellent imaging platform; its DSN compatible telecommunications subsystem can support a 6.4-kbps downlink rate at 3 AU earth range. The spacecraft mass is <200kg at launch to allow launch as a cost-effective secondary payload. It uses proven SEP technology to provide 12km/s of Delta-V, which enables multiple rendezvous' in a single mission. Cost-effectiveness is optimized by launch as a secondary payload (e.g., Ariane-5 ASAP) or as a multiple manifest on a single dedicated launch vehicle (e.g., 4 on a Delta-II 2925). Following separation from the LV, we describe a candidate mission profile that minimizes cost by using the spacecraft's 12km/s of SEP Delta-V to allow orbiting up to 4 separate NEO's. Orbiting as opposed to flying by augments the mission's science return by providing the NEO mass and by allowing multiple phase angle imaging. The NEOX Spacecraft has the capability to support a 20kg payload drawing 100W average during SEP cruise, with >1kW available during the NEO orbital phase when the SEP thrusters are not powered. We will present a candidate payload suite that includes a visible/NIR imager, a laser altimeter, and a set of small, self-righting surface probes that can be used to assess the geophysical state of the object surface and near-surface environments. The surface probe payload notionally includes a set of cameras for imaging the body surface at mm-scale resolution, an accelerometer package to measure surface mechanical properties upon probe impact, a Langmuir probe to measure the electrostatic gradient immediately above the object surface, and an explosive charge that can be remotely detonated at the end of the surface mission to excavate an artificial crater that can be remotely observed from the orbiting spacecraft.

SMART: The Future of Spaceflight Avionics

NASA Technical Reports Server (NTRS)

Alhorn, Dean C.; Howard, David E.

2010-01-01

A novel avionics approach is necessary to meet the future needs of low cost space and lunar missions that require low mass and low power electronics. The current state of the art for avionics systems are centralized electronic units that perform the required spacecraft functions. These electronic units are usually custom-designed for each application and the approach compels avionics designers to have in-depth system knowledge before design can commence. The overall design, development, test and evaluation (DDT&E) cycle for this conventional approach requires long delivery times for space flight electronics and is very expensive. The Small Multi-purpose Advanced Reconfigurable Technology (SMART) concept is currently being developed to overcome the limitations of traditional avionics design. The SMART concept is based upon two multi-functional modules that can be reconfigured to drive and sense a variety of mechanical and electrical components. The SMART units are key to a distributed avionics architecture whereby the modules are located close to or right at the desired application point. The drive module, SMART-D, receives commands from the main computer and controls the spacecraft mechanisms and devices with localized feedback. The sensor module, SMART-S, is used to sense the environmental sensors and offload local limit checking from the main computer. There are numerous benefits that are realized by implementing the SMART system. Localized sensor signal conditioning electronics reduces signal loss and overall wiring mass. Localized drive electronics increase control bandwidth and minimize time lags for critical functions. These benefits in-turn reduce the main processor overhead functions. Since SMART units are standard flight qualified units, DDT&E is reduced and system design can commence much earlier in the design cycle. Increased production scale lowers individual piece part cost and using standard modules also reduces non-recurring costs. The benefit list continues, but the overall message is already evident: the SMART concept is an evolution in spacecraft avionics. SMART devices have the potential to change the design paradigm for future satellites, spacecraft and even commercial applications.

Training for spacecraft technical analysts

NASA Technical Reports Server (NTRS)

Ayres, Thomas J.; Bryant, Larry

1989-01-01

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

Characterization of Magnetospheric Spacecraft Charging Environments Using the LANL Magnetospheric Plasma Analyzer Data Set

NASA Technical Reports Server (NTRS)

Hardage, Donna (Technical Monitor); Davis, V. A.; Mandell, M. J.; Thomsen, M. F.

2003-01-01

An improved specification of the plasma environment has been developed for use in modeling spacecraft charging. It was developed by statistically analyzing a large part of the LANL Magnetospheric Plasma Analyzer (MPA) data set for ion and electron spectral signature correlation with spacecraft charging, including anisotropies. The objective is to identify a relatively simple characterization of the full particle distributions that yield an accurate predication of the observed charging under a wide variety of conditions.

Fire extinguishment and inhibition in spacecraft environments

NASA Technical Reports Server (NTRS)

Deris, John

1987-01-01

It was concluded that it is essential that NASA develop a comprehensive approach to fire extinguishment and inerting in spacecraft environments. Electronic equipment might be easily protected through use of an onboard inert gas generating system. The use of Halon 1301 presents serious technological challenges for agent cleanup and removal of the toxic and corrosive products of combustion. Nitrogen pressurization, while effective, probably presents a serious weight penality. The use of liquid water sprays appears to be the most effective approach to general purpose spacecraft fire protection.

Brane Craft

NASA Technical Reports Server (NTRS)

Janson, Siegfried

2017-01-01

A Brane Craft is a membrane spacecraft with solar cells, command and control electronics, communications systems, antennas, propulsion systems, attitude and proximity sensors, and shape control actuators as thin film structures manufactured on 10 micron thick plastic sheets. This revolutionary spacecraft design can have a thickness of tens of microns with a surface area of square meters to maximize area-to-mass ratios for exceptionally low-mass spacecraft. Communications satellites, solar power satellites, solar electric propulsion stages, and solar sails can benefit from Brane Craft design. It also enables new missions that require low-mass spacecraft with exceptionally high delta-V. Active removal of orbital debris from Earth orbit is the target application for this study.

Time delay occultation data of the Helios spacecraft for probing the electron density distribution in the solar corona

NASA Technical Reports Server (NTRS)

Edenhofer, P.; Lueneburg, E.; Esposito, P. B.; Martin, W. L.; Zygielbaum, A. I.; Hansen, R. T.; Hansen, S. F.

1978-01-01

S-band time delay measurements were collected from the spacecraft Helios A and B during three solar occultations in 1975/76 within heliocentric distances of about 3 and 215 earth radius in terms of range, Doppler frequency shift, and electron content. Characteristic features of measurement and data processing are described. Typical data sets are discussed to probe the electron density distribution near the sun (west and east limb as well) including the outer and extended corona. Steady-state and dynamical aspects of the solar corona are presented and compared with earth-bound-K-coronagraph measurements. Using a weighted least squares estimation, parameters of an average coronal electron density profile are derived in a preliminary analysis to yield electron densities at r = 3, 65, 215 earth radius. Transient phenomena are discussed and a velocity of propagation v is nearly equal to 900 km/s is determined for plasma ejecta from a solar flare observed during an extraordinary set of Helios B electron content measurements.

Electron distributions upstream of the Comet Halley bow shock - Evidence for adiabatic heating

NASA Technical Reports Server (NTRS)

Larson, D. E.; Anderson, K. A.; Lin, R. P.; Carlson, C. W.; Reme, H.; Glassmeier, K. H.; Neubauer, F. M.

1992-01-01

Three-dimensional plasma electron (22 eV to 30 keV) observations upstream of Comet Halley bow shock, obtained by the RPA-1 COPERNIC (Reme Plasma Analyzer - Complete Positive Ion, Electron and Ram Negative Ion Measurements near Comet Halley) experiment on the Giotto spacecraft are reported. Besides electron distributions typical of the undisturbed solar wind and backstreaming electrons observed when the magnetic field line intersects the cometary bow shock, a new type of distribution, characterized by enhanced low energy (less than 100 eV) flux which peaks at 90-deg pitch angles is found. These are most prominent when the spacecraft is on field lines which pass close to but are not connected to the bow shock. The 90-deg pitch angle electrons appear to have been adiabatically heated by the increase in the magnetic field strength resulting from the compression of the upstream solar wind plasma by the cometary mass loading. A model calculation of this effect which agrees qualitatively with the observed 90-deg flux enhancements is presented.

An interstellar precursor mission

NASA Technical Reports Server (NTRS)

Jaffe, L. D.; Ivie, C.; Lewis, J. C.; Lipes, R. G.; Norton, H. N.; Stearns, J. W.; Stimpson, L.; Weissman, P.

1977-01-01

A mission out of the planetary system, with launch about the year 2000, could provide valuable scientific data as well as test some of the technology for a later mission to another star. Primary scientific objectives for the precursor mission concern characteristics of the heliopause, the interstellar medium, stellar distances (by parallax measurements), low energy cosmic rays, interplanetary gas distribution, and mass of the solar system. Secondary objectives include investigation of Pluto. Candidate science instruments are suggested. Individual spacecraft systems for the mission were considered, technology requirements and problem areas noted, and a number of recommendations made for technology study and advanced development. The most critical technology needs include attainment of 50-yr spacecraft lifetime and development of a long-life NEP system.

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

NASA Astrophysics Data System (ADS)

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

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

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

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

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

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

Insulating Material for Next-Generation Spacecraft

NASA Technical Reports Server (NTRS)

White, Susan; Johnson, Sylvia; Salerno, Louis; Kittel, Peter; Roach, Pat; Helvensteijn, Ben; Kashani, Ali

2006-01-01

A report discusses the development of a flexible thermal-insulation material for cryogenic tanks in next-generation spacecraft. This material is denoted Advanced Reusable All-temperature Multimode Insulation System (ARAMIS). The report begins by describing the need for ARAMIS and the technological challenges of developing a single material that is useable throughout the temperature range from storage of liquid hydrogen (20 K) to atmospheric-reentry heating (>2,000 K), has the requisite low thermal conductivity, resists condensation of moisture without need for a gas purge, and withstands reentry heating for a 400-mission lifetime. The report then discusses laboratory apparatuses for testing materials that have been and will be considered as candidates for the development of ARAMIS.

Radar systems for the water resources mission, volume 1

NASA Technical Reports Server (NTRS)

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Hanson, B. C.; Komen, M. J.; Mcmillan, S. B.; Parashar, S. K.

1976-01-01

The state of the art determination was made for radar measurement of: soil moisture, snow, standing and flowing water, lake and river ice, determination of required spacecraft radar parameters, study of synthetic-aperture radar systems to meet these parametric requirements, and study of techniques for on-board processing of the radar data. Significant new concepts developed include the following: scanning synthetic-aperture radar to achieve wide-swath coverage; single-sideband radar; and comb-filter range-sequential, range-offset SAR processing. The state of the art in radar measurement of water resources parameters is outlined. The feasibility for immediate development of a spacecraft water resources SAR was established. Numerous candidates for the on-board processor were examined.

Internal charging analysis tools, NUMIT 2.0 and 3D NUMIT, and those applications on Europa Clipper and Juno missions

NASA Astrophysics Data System (ADS)

Kim, W.; Chinn, J. Z.; Katz, I.; Jun, I.; Garrett, H. B.

2016-12-01

One of the major concerns in the spacecraft design due to natural space environment interaction is the internal charging in dielectric materials and floating conductors, especially for missions encountering a high radiation environment such as NASA's Juno and proposed Europa Clipper Missions. Sufficiently energetic electrons can penetrate the spacecraft structure or electronics chassis and stop within dielectrics and floating conductors. Electrons can accumulate in dielectrics over time due to the dielectrics' very low conductivity. If the electric field resulting from a charge buildup becomes higher than the breakdown threshold of the dielectric, discharge may occur, potentially damaging near-by sensitive electronics. Indeed, numerous spacecraft anomalies and failures have been attributed to this phenomenon, referred to as internal electrostatic discharge (iESD). Therefore, accurate assessment of the risk of iESD for a given space environment and dielectric geometry is important for spacecraft reliability. To evaluate the risk of iESD, we developed a general three dimensional internal charge analyses method, 3D NUMIT by combining a Monte Carlo radiation transport simulation tool such as MCNPX or GEANT4 and a commercial FEA software such as COMSOL. Also for a simple and fast internal charging assessment, we significantly improved the widely used one dimensional internal charging assessment code, NUMIT and named NUMIT 2.0. We will show the new features of NUMIT 2.0 and the capability of 3D NUMIT with several examples of applications of those tools to iESD assessments on Juno and Europa Clipper Missions.

Omni-directional Particle Detector (ODPD) on Tiangong-2 Spacecraft

NASA Astrophysics Data System (ADS)

Guohong, S.; Zhang, S.; Yang, X.; Wang, C.

2017-12-01

Tiangong-2 spacecraft is the second space laboratory independently developed by china after Tiangong-1, which was launched on 15 September 2016. It is also the first real space laboratory in china, which will be used to further validate the space rendezvous and docking technology and to carry out a series of space tests. The spacecraft's orbit is 350km height and 42° inclination. The omni-directional particle detector (ODPD) on Tiangong-2 spacecraft is a new instrument developed by China. Its goal is the anisotropy and energy spectra of space particles on manned space flight orbit. The ODPD measures the energy spectra and pitch angle distributions of high energy electrons and protons. It consists of one electron spectrum telescope, one proton spectrum telescope and sixteen directional flux telescopes. The ODPD is designed to measure the protons spectrum from 2.5MeV to 150MeV, electrons spectrum from 0.2MeV to 1.5MeV, the flux of electrons energy >200keV and protons energy>1.5MeV on 2∏ space, also the ODPD has a small sensor to measure the LET spectrum from 1-100MeV/cm2sr. The primary advantage can give the particle's pitch angle distributions at any time because of the sixteen flux telescopes arrange form 0 to 180 degree. This is the first paper dealing with ODPD data, so we firstly spend some time describing the instrument, its theory of operation and its calibration. Then we give the preliminary detecting results.

Electron density distribution and solar plasma correction of radio signals using MGS, MEX, and VEX spacecraft navigation data and its application to planetary ephemerides

NASA Astrophysics Data System (ADS)

Verma, A. K.; Fienga, A.; Laskar, J.; Issautier, K.; Manche, H.; Gastineau, M.

2013-02-01

The Mars Global Surveyor (MGS), Mars Express (MEX), and Venus Express (VEX) experienced several superior solar conjunctions. These conjunctions cause severe degradations of radio signals when the line of sight between the Earth and the spacecraft passes near to the solar corona region. The primary objective of this work is to deduce a solar corona model from the spacecraft navigation data acquired at the time of solar conjunctions and to estimate its average electron density. The corrected or improved data are then used to fit the dynamical modeling of the planet motions, called planetary ephemerides. We analyzed the radio science raw data of the MGS spacecraft using the orbit determination software GINS. The range bias, obtained from GINS and provided by ESA for MEX and VEX, are then used to derive the electron density profile. These profiles are obtained for different intervals of solar distances: from 12 R⊙ to 215 R⊙ for MGS, 6 R⊙ to 152 R⊙ for MEX, and from 12 R⊙ to 154 R⊙ for VEX. They are acquired for each spacecraft individually, for ingress and egress phases separately and both phases together, for different types of solar winds (fast, slow), and for solar activity phases (minimum, maximum). We compared our results with the previous estimations that were based on in situ measurements, and on solar type III radio and radio science studies made at different phases of solar activity and at different solar wind states. Our results are consistent with estimations obtained by these different methods. Moreover, fitting the planetary ephemerides including complementary data that were corrected for the solar corona perturbations, noticeably improves the extrapolation capability of the planetary ephemerides and the estimation of the asteroids masses. Tables 5, 6 and Appendix A are available in electronic form at http://www.aanda.org

Radio science electron density profiles of lunar ionosphere based on the service module of circumlunar return and reentry spacecraft

NASA Astrophysics Data System (ADS)

Wang, M.; Han, S.; Ping, J.; Tang, G.; Zhang, Q.

2017-09-01

The existence of lunar ionosphere has been under debate for a long time. Radio occultation experiments had been performed by both Luna 19/22 and SELENE missions and electron column density of lunar ionosphere was provided. The Apollo 14 mission also acquired the electron density with in situ measurements. But the results of these missions don't well-matched. In order to explore the lunar ionosphere, radio occultation with the service module of Chinese circumlunar return and reentry spacecraft has been performing. One coherent S-band and X-band radio signals were recorded by China deep space stations, and local correlation was adopted to compute carrier phases of both signals. Based on the above work, the electron density profiles of lunar ionosphere was obtained and analyzed.

Titan/Centaur D-1T TC-2, Helios A flight data report. [of space missions

NASA Technical Reports Server (NTRS)

1975-01-01

Background data of spacecraft launching and flight are presented. A system analysis of the space vehicles is included, specifically on: (1) electronic equipment, (2) hydraulic equipment, (3) telemetry, (4) propulsion systems, (5) software (computers), and (6) guidance. Spacecraft and launch vehicle configurations are shown and described.

Our Solar System at a Glance. Information Summaries.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

The United States has explored the solar system with automated spacecraft and human-crewed expeditions that have produced a quantum leap in our knowledge and understanding of the solar system. Through the electronic sight and other "senses" of our automated spacecraft, color and complexion have been given to worlds that for centuries…

Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm

PubMed Central

Nakamura, R.; Sergeev, V. A.; Baumjohann, W.; Owen, C. J.; Petrukovich, A. A.; Yao, Z.; Nakamura, T. K. M.; Kubyshkina, M. V.; Sotirelis, T.; Burch, J. L.; Genestreti, K. J.; Vörös, Z.; Andriopoulou, M.; Gershman, D. J.; Avanov, L. A.; Magnes, W.; Russell, C. T.; Plaschke, F.; Khotyaintsev, Y. V.; Giles, B. L.; Coffey, V. N.; Dorelli, J. C.; Strangeway, R. J.; Torbert, R. B.; Lindqvist, P.‐A.; Ergun, R.

2017-01-01

Abstract During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they simultaneously crossed the reconnection separatrix layer during this very intense reconnection event. These include (1) energy dispersion of the energetic ions and electrons traveling earthward, accompanied with high electron energies in the vicinity of the separatrix; (2) energy dispersion of polar rain electrons, with a high‐energy cutoff; and (3) intense inward convection of the magnetic field lines at the MMS location. The high temporal resolution measurements by MMS provide unprecedented observations of the outermost electron boundary layer. We discuss the relevance of the energy dispersion of the electrons, and their pitch angle distribution, to the spatial and temporal evolution of the boundary layer. The results indicate that the underlying magnetotail magnetic reconnection process was an intrinsically impulsive and the active X‐line was located relatively close to the Earth, approximately at 16–18 RE. PMID:29399431

Measurements Verifying the Optics of the Electron Drift Instrument

NASA Astrophysics Data System (ADS)

Kooi, Vanessa; Kletzing, Craig; Bounds, Scott; Sigsbee, Kristine M.

2015-04-01

Magnetic reconnection is the process of breaking and reconnecting of opposing magnetic field lines, and is often associated with tremendous energy transfer. The energy transferred by reconnection directly affects people through its influence on geospace weather and technological systems - such as telecommunication networks, GPS, and power grids. However, the mechanisms that cause magnetic reconnection are not well understood. The Magnetospheric Multi-Scale Mission (MMS) will use four spacecraft in a pyramid formation to make three-dimensional measurements of the structures in magnetic reconnection occurring in the Earth's magnetosphere.The spacecraft will repeatedly sample these regions for a prolonged period of time to gather data in more detail than has been previously possible. MMS is scheduled to be launched in March of 2015. The Electron Drift Instrument (EDI) will be used on MMS to measure the electric fields associated with magnetic reconnection. The EDI is a device used on spacecraft to measure electric fields by emitting an electron beam and measuring the E x B drift of the returning electrons after one gyration. This paper concentrates on measurements of the EDI’s optics system. The testing process includes measuring the optics response to a uni-directional electron beam. These measurements are used to verify the response of the EDI's optics and to allow for the optimization of the desired optics state. The measurements agree well with simulations and we are confident in the performance of the EDI instrument.

Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm

NASA Astrophysics Data System (ADS)

Varsani, A.; Nakamura, R.; Sergeev, V. A.; Baumjohann, W.; Owen, C. J.; Petrukovich, A. A.; Yao, Z.; Nakamura, T. K. M.; Kubyshkina, M. V.; Sotirelis, T.; Burch, J. L.; Genestreti, K. J.; Vörös, Z.; Andriopoulou, M.; Gershman, D. J.; Avanov, L. A.; Magnes, W.; Russell, C. T.; Plaschke, F.; Khotyaintsev, Y. V.; Giles, B. L.; Coffey, V. N.; Dorelli, J. C.; Strangeway, R. J.; Torbert, R. B.; Lindqvist, P.-A.; Ergun, R.

2017-11-01

During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they simultaneously crossed the reconnection separatrix layer during this very intense reconnection event. These include (1) energy dispersion of the energetic ions and electrons traveling earthward, accompanied with high electron energies in the vicinity of the separatrix; (2) energy dispersion of polar rain electrons, with a high-energy cutoff; and (3) intense inward convection of the magnetic field lines at the MMS location. The high temporal resolution measurements by MMS provide unprecedented observations of the outermost electron boundary layer. We discuss the relevance of the energy dispersion of the electrons, and their pitch angle distribution, to the spatial and temporal evolution of the boundary layer. The results indicate that the underlying magnetotail magnetic reconnection process was an intrinsically impulsive and the active X-line was located relatively close to the Earth, approximately at 16-18 RE.

Comparative study of energetic heliospheric electrons at wind and geotail

NASA Technical Reports Server (NTRS)

Chaizy, P. A.; Lanzerotti, L. J.; Lin, R. P.; Lepping, R. P.; Kokubun, S. K.; Bosqued, J.-M.; Sanderson, T. R.; Yamamoto, T.

1997-01-01

The current fleet of both heliospheric and magnetospheric spacecraft provides a unique opportunity of studying spatio-temporal plasma phenomena. Among the numerous topics that can be addressed by such a fleet, figures the 3D study of energetic (greater than 20 keV) solar electron) solar electron events. WIND and GEOTAIL are particulary interesting for such analysis: more than two years of data; up to 3/4 continuous days spent by GEOTAIL in the solar wind; and comparable experiments. During solar electron events, rapid electron flux changes can be associated with these structures. Sometimes they are seen at both spacecraft with a time difference corresponding to the convection time, but sometimes they are observed at one spacecraft but not at the other. Several preliminary conclusions can be drawn from such events: (1) there is direct evidence that, within distances lower than 1.5 x 10(exp 6) km at 1 A (approximately 7000 km at the sun), there are significant spatial variations of (a) the magnetic field line connections to the source region and probably of (b) the particle propagation features; (2) magnetic field lines inside and outside particle propagation structures can keep distinct access to the source region for more than one hour; (3) flux waves, of probable local origin, were observed; and (4) within one hour, spatial flux discrepancies, separated by magnetic structures, may remain or disappear.

Juno Radio Science Observations and Gravity Science Calibrations of Plasma Electron Content in Io Plasma Torus

NASA Astrophysics Data System (ADS)

Yang, Y. M.; Buccino, D.; Folkner, W. M.; Oudrhiri, K.; Phipps, P. H.; Parisi, M.; Kahan, D. S.

2017-12-01

Interplanetary and Earth ionosphere plasma electrons can have significant impacts on radio frequency signal propagation such as telecommunication between spacecraft and the Deep Space Network (DSN). On 27 August 2016, the first closest approach of The Juno spacecraft (Perijove 1) provided an opportunity to observe plasma electrons inside of the Io plasma torus using radio science measurements from Juno. Here, we report on the derivations of plasma electron content in the Io plasma torus by using two-way coherent radio science measurements made from Juno's Gravity Science Instrument and the Deep Space Network. During Perijove 1, Juno spacecraft passed through the inner region (perijove altitude of 1.06 Jovian Radii) between Jupiter and the Io plasma torus. Significant plasma electron variations of up to 30 TEC units were observed while the radio link between Juno and the DSN traveled through the Io plasma torus. In this research, we compare observations made by open-loop and closed-loop processes using different frequency radio signals, corresponding Io plasma torus model simulations, and other Earth ionosphere observations. The results of three-dimensional Io plasma model simulations are consistent with observations with some discrepancies. Results are shown to improve our understanding of the Io plasma torus effect on Juno gravity science measurements and its calibrations to reduce the corresponding (non-gravity field induced) radio frequency shift.

Design of an FPGA-based electronic flow regulator (EFR) for spacecraft propulsion system

NASA Astrophysics Data System (ADS)

Manikandan, J.; Jayaraman, M.; Jayachandran, M.

2011-02-01

This paper describes a scheme for electronically regulating the flow of propellant to the thruster from a high-pressure storage tank used in spacecraft application. Precise flow delivery of propellant to thrusters ensures propulsion system operation at best efficiency by maximizing the propellant and power utilization for the mission. The proposed field programmable gate array (FPGA) based electronic flow regulator (EFR) is used to ensure precise flow of propellant to the thrusters from a high-pressure storage tank used in spacecraft application. This paper presents hardware and software design of electronic flow regulator and implementation of the regulation logic onto an FPGA.Motivation for proposed FPGA-based electronic flow regulation is on the disadvantages of conventional approach of using analog circuits. Digital flow regulation overcomes the analog equivalent as digital circuits are highly flexible, are not much affected due to noise, accurate performance is repeatable, interface is easier to computers, storing facilities are possible and finally failure rate of digital circuits is less. FPGA has certain advantages over ASIC and microprocessor/micro-controller that motivated us to opt for FPGA-based electronic flow regulator. Also the control algorithm being software, it is well modifiable without changing the hardware. This scheme is simple enough to adopt for a wide range of applications, where the flow is to be regulated for efficient operation.The proposed scheme is based on a space-qualified re-configurable field programmable gate arrays (FPGA) and hybrid micro circuit (HMC). A graphical user interface (GUI) based application software is also developed for debugging, monitoring and controlling the electronic flow regulator from PC COM port.

Effect of Voltage Level on Power System Design for Solar Electric Propulsion Missions

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.

2003-01-01

This paper presents study results quantifying the benefits of higher voltage, electric power system designs for a typical solar electric propulsion spacecraft Earth orbiting mission. A conceptual power system architecture was defined and design points were generated for system voltages of 28-V, 50-V, 120-V, and 300-V using state-of-the-art or advanced technologies. A 300-V 'direct-drive' architecture was also analyzed to assess the benefits of directly powering the electric thruster from the photovoltaic array without up-conversion. Fortran and spreadsheet computational models were exercised to predict the performance and size power system components to meet spacecraft mission requirements. Pertinent space environments, such as electron and proton radiation, were calculated along the spiral trajectory. In addition, a simplified electron current collection model was developed to estimate photovoltaic array losses for the orbital plasma environment and that created by the thruster plume. The secondary benefits of power system mass savings for spacecraft propulsion and attitude control systems were also quantified. Results indicate that considerable spacecraft wet mass savings were achieved by the 300-V and 300-V direct-drive architectures.

Electrostatic-probe measurements of plasma parameters for two reentry flight experiments at 25000 feet per second

NASA Technical Reports Server (NTRS)

Jones, W. L., Jr.; Cross, A. E.

1972-01-01

Unique plasma diagnostic measurements at high altitudes from two geometrically similar blunt body reentry spacecraft using electrostatic probe rakes are presented. The probes measured the positive ion density profiles (shape and magnitude) during the two flights. The probe measurements were made at eight discrete points (1 cm to 7 cm) from the vehicle surface in the aft flow field of the spacecraft over the altitude range of 85.3 to 53.3 km (280,000 to 175,000 ft) with measured densities of 10 to the 8th power to 10 to the 12th power electrons/cu cm, respectively. Maximum reentry velocity for each spacecraft was approximately 7620 meters/second (25,000 ft/sec). In the first flight experiment, water was periodically injected into a flow field which was contaminated by ablation products from the spacecraft nose region. The nonablative nose of the second spacecraft thereby minimized flow field contamination. Comparisons of the probe measured density profiles with theoretical calculations are presented with discussion as to the probable cause of significant disagreement. Also discussed are the correlation of probe measurements with vehicle angle of attack motions and the good high altitude agreement between electron densities inferred from the probe measurements, VHF antenna measurements, and microwave reflectometer diagnostic measurements.

Radiation Dose Testing on Juno High Voltage Cables

NASA Technical Reports Server (NTRS)

Green, Nelson W.; Kirkham, Harold; Kim, Wousik; McAlpine, Bill

2008-01-01

The Juno mission to Jupiter will have a highly elliptical orbit taking the spacecraft through the radiation belts surrounding the planet. During these passes through the radiation belts, the spacecraft will be subject to high doses of radiation from energetic electrons and protons with energies ranging from 10 keV to 1 GeV. While shielding within the spacecraft main body will reduce the total absorbed dose to much of the spacecraft electronics, instruments and cables on the outside of the spacecraft will receive much higher levels of absorbed dose. In order to estimate the amount of degradation to two such cables, testing has been performed on two coaxial cables intended to provide high voltages to three of the instruments on Juno. Both cables were placed in a vacuum of 5x10(exp -6) torr and cooled to -50(deg)C prior to exposure to the radiation sources. Measurements of the coaxial capacitance per unit length and partial discharge noise floor indicate that increasing levels of radiation make measurable but acceptably small changes to the F EP Teflon utilized in the construction of these cables. In addition to the radiation dose testing, observations were made on the internal electrostatic charging characteristics of these cables and multiple discharges were recorded.

Radiation Dose Testing on Juno High Voltage Cables

NASA Technical Reports Server (NTRS)

Green, Nelson W.; Kirkham, Harold; Kim, Wousik; McAlpine, Bill

2008-01-01

The Juno mission to Jupiter will have a highly elliptical orbit taking the spacecraft through the radiation belts surrounding the planet. During these passes through the radiation belts, the spacecraft will be subject to high doses of radiation from energetic electrons and protons with energies ranging from 10 keV to 1 GeV. While shielding within the spacecraft main body will reduce the total absorbed dose to much of the spacecraft electronics, instruments and cables on the outside of the spacecraft will receive much higher levels of absorbed dose. In order to estimate the amount of degradation to two such cables, testing has been performed on two coaxial cables intended to provide high voltages to three of the instruments on Juno. Both cables were placed in a vacuum of 5x10-6 torr and cooled to -50 C prior to exposure to the radiation sources. Measurements of the coaxial capacitance per unit length and partial discharge noise floor indicate that increasing levels of radiation make measurable but acceptably small changes to the F EP Teflon utilized in the construction of these cables. In addition to the radiation dose testing, observations were made on the internal electrostatic charging characteristics of these cables and multiple discharges were recorded.

Does a Local B-Minimum Appear in the Tail Current Sheet During a Substorm Growth Phase?

NASA Astrophysics Data System (ADS)

Sergeev, V. A.; Gordeev, E. I.; Merkin, V. G.; Sitnov, M. I.

2018-03-01

Magnetic configurations with dBz/dr > 0 in the midtail current sheet are potentially unstable to various instabilities associated with the explosive substorm onset. Their existence is hard to confirm with observations of magnetospheric spacecraft. Here we use remote sensing by low-altitude spacecraft that measured the loss cone filling rate during electron-rich solar particle event, providing information about magnetic properties of the tail current sheet. We found a latitudinally localized anisotropic 30 keV electron loss cone region embedded inside an extended region of isotropic solar electron precipitation. It was persistently observed for more than 0.5 h during isolated growth phase event by six Polar Operational Environmental Satellites spacecraft, which crossed the premidnight auroral oval. The embedded anisotropic region was observed 1° poleward of the outer radiation belt boundary over 4-5 h wide magnetic local time sector, suggesting a persistent ridge-type Bz2/j maximum in the equatorial plasma sheet at distances 15-20 RE. We discuss infrequent observations of such events taking into account recent results of global magnetohydrodynamic simulations.

ISTP SBIR phase 1 Full-Sky Scanner: A feasibility study

NASA Technical Reports Server (NTRS)

1986-01-01

The objective was to develop a Full-Sky Sensor (FSS) to detect the Earth, Sun and Moon from a spinning spacecraft. The concept adopted has infinitely variable resolution. A high-speed search mode is implemented on the spacecraft. The advantages are: (1) a single sensor determines attitude parameters from Earth, Sun and Moon, thus eliminating instrument mounting errors; (2) the bias between the actual spacecraft spin axis and the intended spin axis can be determined; (3) cost is minimized; and (4) ground processing is straightforward. The FSS is a modification of an existing flight-proven sensor. Modifications to the electronics are necessary to accommodate the amplitude range and signal width range of the celestial bodies to be detected. Potential applications include ISTP missions, Multi-Spacecraft Satellite Program (MSSP), dual-spin spacecraft at any altitude, spinning spacecraft at any altitude, and orbit parameter determination for low-Earth orbits.

ISTP SBIR phase 1 Full-Sky Scanner: A feasibility study

NASA Astrophysics Data System (ADS)

1986-08-01

The objective was to develop a Full-Sky Sensor (FSS) to detect the Earth, Sun and Moon from a spinning spacecraft. The concept adopted has infinitely variable resolution. A high-speed search mode is implemented on the spacecraft. The advantages are: (1) a single sensor determines attitude parameters from Earth, Sun and Moon, thus eliminating instrument mounting errors; (2) the bias between the actual spacecraft spin axis and the intended spin axis can be determined; (3) cost is minimized; and (4) ground processing is straightforward. The FSS is a modification of an existing flight-proven sensor. Modifications to the electronics are necessary to accommodate the amplitude range and signal width range of the celestial bodies to be detected. Potential applications include ISTP missions, Multi-Spacecraft Satellite Program (MSSP), dual-spin spacecraft at any altitude, spinning spacecraft at any altitude, and orbit parameter determination for low-Earth orbits.

Cryogenic thermal conductivity measurements on candidate materials for space missions

NASA Astrophysics Data System (ADS)

Tuttle, James; Canavan, Edgar; Jahromi, Amir

2017-12-01

Spacecraft and instruments on space missions are built using a wide variety of carefully-chosen materials. It is common for NASA engineers to propose new candidate materials which have not been totally characterized at cryogenic temperatures. In many cases a material's cryogenic thermal conductivity must be known before selecting it for a specific space-flight application. We developed a test facility in 2004 at NASA's Goddard Space Flight Center to measure the longitudinal thermal conductivity of materials at temperatures between 4 and 300 K, and we have characterized many candidate materials since then. The measurement technique is not extremely complex, but proper care to details of the setup, data acquisition and data reduction is necessary for high precision and accuracy. We describe the thermal conductivity measurement process and present results for ten engineered materials, including alloys, polymers, composites, and a ceramic.

Preliminary analysis of coronal electron content measurements from spacecraft Helios A around first solar occultation

NASA Technical Reports Server (NTRS)

Edenhofer, P.; Esposito, P. B.; Martin, W. L.; Zygielbaum, A. I.; Hansen, R. T.; Hansen, S. F.; Lueneburg, E.

1977-01-01

Steady-state and dynamical features of the electron density distribution in the solar corona emerge from a preliminary analysis of Helios A electron content measurements. There are strong indications that correlations can be established with earth-bound K-coronagraph measurements.

Modeling of environmentally induced transients within satellites

NASA Technical Reports Server (NTRS)

Stevens, N. John; Barbay, Gordon J.; Jones, Michael R.; Viswanathan, R.

1987-01-01

A technique is described that allows an estimation of possible spacecraft charging hazards. This technique, called SCREENS (spacecraft response to environments of space), utilizes the NASA charging analyzer program (NASCAP) to estimate the electrical stress locations and the charge stored in the dielectric coatings due to spacecraft encounter with a geomagnetic substorm environment. This information can then be used to determine the response of the spacecraft electrical system to a surface discharge by means of lumped element models. The coupling into the electronics is assumed to be due to magnetic linkage from the transient currents flowing as a result of the discharge transient. The behavior of a spinning spacecraft encountering a severe substorm is predicted using this technique. It is found that systems are potentially vulnerable to upset if transient signals enter through the ground lines.

Assessing Pre-Service Candidates' Web-Based Electronic Portfolios.

ERIC Educational Resources Information Center

Lamson, Sharon; Thomas, Kelli R.; Aldrich, Jennifer; King, Andy

This paper describes processes undertaken by Central Missouri State University's Department of Curriculum and Instruction to prepare teacher candidates to create Web-based professional portfolios, Central's expectations for content coverage within the electronic portfolios, and evaluation procedures. It also presents data on portfolio construction…

ScienceCast 202: Escape of the Destructive Electrons

NASA Image and Video Library

2015-12-14

Earth is surrounded by electrons that can be disruptive to our technology. NASA is using high-altitude balloons and spacecraft to monitor and understand these particles in the radiation belts surrounding our planet.

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.

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Astrophysics Data System (ADS)

Barrie, A. C.; Adrian, M. L.; Yeh, P.; Winkert, G. E.; Lobell, J. V.; Viňas, A. F.; Simpson, D. G.; Moore, T. E.

2008-12-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6° × 180° fields-of-view (FOV) are set 90° apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° × 180° fan about the its nominal viewing (0° deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 7.6-Mb s-1. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mb s-1. Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present simulations of the CCSDS 122.0-B-1 algorithm- based compression of the FPI-DES electron data. Compression analysis is based upon a seed of re- processed Cluster/PEACE electron measurements. Topics to be discussed include: (i) Review of compression algorithm; (ii) Data quality; (iii) Data formatting/organization; (iv) Compression optimization; and (v) Implications for data/matrix pruning. We conclude with a presentation of the base-lined FPI data compression approach.

The 1983 tail-era series. Volume 1: ISEE 3 plasma

NASA Technical Reports Server (NTRS)

Fairfield, D. H.; Phillips, J. L.

1991-01-01

Observations from the ISEE 3 electron analyzer are presented in plots. Electrons were measured in 15 continuous energy levels between 8.5 and 1140 eV during individual 3-sec spacecraft spins. Times associated with each data point are the beginning time of the 3 sec data collection interval. Moments calculated from the measured distribution function are shown as density, temperature, velocity, and velocity azimuthal angle. Spacecraft ephemeris is shown at the bottom in GSE and GSM coordinates in units of Earth radii, with vertical ticks on the time axis corresponding to the printed positions.

Energy Dependence of Electron-Scale Currents and Dissipation During Magnetopause Reconnection

NASA Astrophysics Data System (ADS)

Shuster, J. R.; Gershman, D. J.; Giles, B. L.; Dorelli, J.; Avanov, L. A.; Chen, L. J.; Wang, S.; Bessho, N.; Torbert, R. B.; Farrugia, C. J.; Argall, M. R.; Strangeway, R. J.; Schwartz, S. J.

2017-12-01

We investigate the electron-scale physics of reconnecting current structures observed at the magnetopause during Phase 1B of the Magnetospheric Multiscale (MMS) mission when the spacecraft separation was less than 10 km. Using single-spacecraft measurements of the current density vector Jplasma = en(vi - ve) enabled by the accuracy of the Fast Plasma Investigation (FPI) electron moments as demonstrated by Phan et al. [2016], we consider perpendicular (J⊥1 and J⊥2) and parallel (J//) currents and their corresponding kinetic electron signatures. These currents can correspond to a variety of structures in the electron velocity distribution functions measured by FPI, including perpendicular and parallel crescents like those first reported by Burch et al. [2016], parallel electron beams, counter-streaming electron populations, or sometimes simply a bulk velocity shift. By integrating the distribution function over only its angular dimensions, we compute energy-dependent 'partial' moments and employ them to characterize the energy dependence of velocities, currents, and dissipation associated with magnetic reconnection diffusion regions caught by MMS. Our technique aids in visualizing and elucidating the plasma energization mechanisms that operate during collisionless reconnection.

Space Weathering Experiments on Spacecraft Materials

NASA Technical Reports Server (NTRS)

Cooper, R.; Cowardin, H.; Engelhar, D.; Plis, Elena; Hoffman, R.

2017-01-01

A project to investigate space environment effects on specific materials with interest to remote sensing was initiated in 2016. The goal of the project is to better characterize changes in the optical properties of polymers and Mylar, specifically those found in multi-layered spacecraft insulation, due to electron bombardment. Previous analysis shows that chemical bonds break and potentially reform when exposed to high energy electrons. Among other properties these chemical changes altered the optical reflectance as documented in laboratory analysis. This paper presents results of the initial experiment results focused on the exposure of materials to various fluences of high energy electrons, used to simulate a portion of the geosynchronous space environment. The paper illustrates how the spectral reflectance changes as a function of time on orbit with respect to GEO environmental factors and investigates the survivability of the material after multiple electron doses. These results provide a baseline for analysis of aging effects on satellite systems used for remote sensing. They also provide preliminary analysis on what materials are most likely to encompass the high area-to-mass population of space debris in the geosynchronous environment. Lastly, the paper provides the results of the initial experimentation as a proof of concept for space aging on polymers and Mylar for conducting more experiments with a larger subset of spacecraft materials.

Architecture Studies Done for High-Rate Duplex Direct Data Distribution (D4) Services

NASA Technical Reports Server (NTRS)

2002-01-01

A study was sponsored to investigate a set of end-to-end system concepts for implementing a high-rate duplex direct data distribution (D4) space-to-ground communications link. The NASA Glenn Research Center is investigating these systems (both commercial and Government) as a possible method of providing a D4 communications service between NASA spacecraft in low Earth orbit and the respective principal investigators using or monitoring instruments aboard these spacecraft. Candidate commercial services were assessed regarding their near-term potential to provide a D4 type of service. The candidates included K-band and V-band geostationary orbit and nongeostationary orbit satellite relay services and direct downlink (D3) services. Internet protocol (IP) networking technologies were evaluated to enable the user-directed distribution and delivery of science data. Four realistic, near-future concepts were analyzed: 1) A duplex direct link (uplink plus downlink communication paths) between a low-Earth-orbit spacecraft and a principal-investigator-based autonomous Earth station; 2) A space-based relay using a future K-band nongeosynchronous-orbit system to handle both the uplink and downlink communication paths; 3) A hybrid link using both direct and relay services to achieve full duplex capability; 4) A dual-mode concept consisting of both a duplex direct link and a space relay duplex link operating independently. The concepts were analyzed in terms of contact time between the NASA spacecraft and the communications service and the achievable data throughput. Throughput estimates for the D4 systems were based on the infusion of advanced communications technology products (single and multibeam K-band phased-arrays and digital modems) being developed by Glenn. Cost estimates were also performed using extrapolated information from both terrestrial and current satellite communications providers. The throughput and cost estimates were used to compare the concepts.

Energetic Particle Propagation in the Inner Heliosphere as Deduced from Low Frequency (less than 100 kHz) Observations of Type III Radio Bursts

NASA Technical Reports Server (NTRS)

Cane, H. V.; Erickson, W. C.

2003-01-01

Solar energetic particle (SEP) events are well-associated with solar flares. It is observed that the delay between the time of the flare and the first-arriving particles at a spacecraft increases with increasing difference between the flare longitude and the footpoint of the field line on which the spacecraft is located. This difference we call the "connection angle" and can be as large as approximately 120 deg. Recently it has been found that all SEP events are preceded by type III radio bursts. These bursts are plasma emission caused by the propagation of 2-50 keV flare electrons through the solar corona and into the solar wind. The drift of these type III radio bursts to lower and lower frequencies enables the propagation of the flare electrons to be traced from the Sun to about 1 AU. We have made an extensive analysis of the type III bursts associated with greater than 20 MeV proton events and find that, in most cases, the radio emission extends to the local plasma frequency when the energetic particles arrive within a few hours of the flare. We conclude that this emission at the lowest possible frequency is generated close to the spacecraft. We then use the time from when the burst started at the Sun to when it reached the local plasma frequency to infer the time it took the radio producing electrons to travel to the spacecraft. We find that these delay times are organized by the connection angle and correlate with the proton delay times. We also find that the differences between the radio delays at Wind and Ulysses are matched by differences in the relative arrival times of the energetic particles at the two spacecraft. The consistent timing between the relative arrival times of energetic electrons and protons and the start of the lowest frequency radio emissions suggests that the first arriving particles of both species are accelerated as part of the flare process and that they propagate to the spacecraft along trajectories similar to those of the lower energy flare electrons. To be detected by observers at locations distant from the nominal field lines originating in the flaring regions the particles must undergo lateral transport. The continuity of the radio bursts suggests that the cross-field transport may occur in the interplanetary medium.

NASCAP simulation of laboratory charging tests using multiple electron guns

NASA Technical Reports Server (NTRS)

Mandell, M. J.; Katz, I.; Parks, D. E.

1981-01-01

NASCAP calculations have been performed simulating exposure of a spacecraft-like model to multiple electron guns. The results agree well with experiment. It is found that magnetic field effects are fairly small, but substantial differential charging can result from electron gun placement. Conditions for surface flashover are readily achieved.

LONGITUDINAL AND RADIAL DEPENDENCE OF SOLAR ENERGETIC PARTICLE PEAK INTENSITIES: STEREO, ACE, SOHO, GOES, AND MESSENGER OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lario, D.; Ho, G. C.; Decker, R. B.

Simultaneous measurements of solar energetic particle (SEP) events by two or more of the spacecraft located near 1 AU during the rising phase of solar cycle 24 (i.e., STEREO-A, STEREO-B, and near-Earth spacecraft such as ACE, SOHO, and GOES) are used to determine the longitudinal dependence of 71-112 keV electron, 0.7-3 MeV electron, 15-40 MeV proton, and 25-53 MeV proton peak intensities measured in the prompt component of SEP events. Distributions of the peak intensities for the selected 35 events with identifiable solar origin are approximated by the form exp [ - ({phi} - {phi}{sub 0}){sup 2}/2{sigma}{sup 2}], where {phi}more » is the longitudinal separation between the parent active region and the footpoint of the nominal interplanetary magnetic field (IMF) line connecting each spacecraft with the Sun, {phi}{sub 0} is the distribution centroid, and {sigma} determines the longitudinal gradient. The MESSENGER spacecraft, at helioradii R < 1 AU, allows us to determine a lower limit to the radial dependence of the 71-112 keV electron peak intensities measured along IMF lines. We find five events for which the nominal magnetic footpoint of MESSENGER was less than 20 Degree-Sign apart from the nominal footpoint of a spacecraft near 1 AU. Although the expected theoretical radial dependence for the peak intensity of the events observed along the same field line can be approximated by a functional form R {sup -{alpha}} with {alpha} < 3, we find two events for which {alpha} > 3. These two cases correspond to SEP events occurring in a complex interplanetary medium that favored the enhancement of peak intensities near Mercury but hindered the SEP transport to 1 AU.« less

Computing in the presence of soft bit errors. [caused by single event upset on spacecraft

NASA Technical Reports Server (NTRS)

Rasmussen, R. D.

1984-01-01

It is shown that single-event-upsets (SEUs) due to cosmic rays are a significant source of single bit error in spacecraft computers. The physical mechanism of SEU, electron hole generation by means of Linear Energy Transfer (LET), it discussed with reference made to the results of a study of the environmental effects on computer systems of the Galileo spacecraft. Techniques for making software more tolerant of cosmic ray effects are considered, including: reducing the number of registers used by the software; continuity testing of variables; redundant execution of major procedures for error detection; and encoding state variables to detect single-bit changes. Attention is also given to design modifications which may reduce the cosmic ray exposure of on-board hardware. These modifications include: shielding components operating in LEO; removing low-power Schottky parts; and the use of CMOS diodes. The SEU parameters of different electronic components are listed in a table.

Energetic particle characteristics of magnetotail flux ropes

NASA Technical Reports Server (NTRS)

Scholer, M.; Klecker, B.; Hovestadt, D.; Gloeckler, G.; Ipavich, F. M.; Galvin, A. B.

1985-01-01

During the recent ISEE-3 Geotail Mission three events have been identified from the magnetometer data which are consistent with a spacecraft crossing of a magnetotail flux rope. Energetic electron and proton observations obtained by the Max-Planck-Institut/University of Maryland sensor system during two of the possible flux rope events are presented. During one event remote sensing of the flux rope with energetic protons reveals that the flux rope is crossed by the spacecraft from south to north. This allows determination of the bandedness of the magnetic field twist and of the flux rope velocity relative to the spacecraft. A minimal flux rope radius of 3 earth radii is derived. Energetic proton intensity is highest just inside of the flux rope and decreases towards the core. Energetic electrons are streaming tailward near the outer boundary, indicating openness of the field lines, and are isotropic through the inner part of the flux rope.

Our Understanding of Space Weather features responsible for geostationary satellite anamolies (P39)

NASA Astrophysics Data System (ADS)

Rajaram, G.; et al.

2006-11-01

girija60@yahoo.com The topic of space weather effects on operational anomalies on spacecraft is one of considerable research investigation, with both pure and applied aspects. This is because of the very high costs involved in fabricating and operating spacecraft, and in insuring them against the harmful effects of space weather. This is more true for geostationary satellites than of low-orbiting spacecraft, as the former operate in the high-risk environment of the Earth’s outer radiation belts, with its large vagaries in spatial and time variations of high- energy electron and proton distributions (BAKER 2003). Without doubt, plasma and magnetic field emissions from active regions on the Sun are the root cause for spacecraft anomalies. Our study for 2005 shows that over 95% of anomalies can be related to some definite activity on the Sun, ranging from high-speed solar wind streams with their 27-day recurrence patterns/coronal holes/coronal mass ejections preceded by X or M type of flares/and magnetic cloud events. The most energetic solar activity events are generally accompanied by a large rise in solar MeV proton densities at geo-stationary orbit (WILKINSON 1994), and they account for definite anomalies classified as SEU (Single Event Upsets which most often are reversible through resetting commands). Any particles in the low energy ranges (eV and keV, and these could be of magnetospheric or ionospheric origin), are believed to cause external charging effects in exposed parts of the spacecraft such as solar power arrays and power cables. These mainly result in power losses which are debilitating over a period of time. The most dangerous and often irrecoverable damage is due to electronics in the 1-5 MeV range which cause deep dielectric discharge of arc type in semi-conductors comprising spacecraft instruments. Following major solar activity, the populations of these rise to more than (5x103) particles/cm2.ster.sec, with large spatial and time variations (LOVE et al. 2000). When the influence of these relativistic electrons in the neighborhood of geo-stationary spacecraft builds up to values exceeding 108/cm2.ster.day, satellite anomalies invariably occur.Our study finds that these ‘Relativistic electron events’ accompanied by satellite anomalies invariably occur following sharp, well-defined shocks in the inter-planetary medium, and we are trying to understand the relationship between the two. We also notice that anomalies due to space weather effects are very satellite-specific, with differing threshold values seen for different satellites.

Cross-comparison of spacecraft-environment interaction model predictions applied to Solar Probe Plus near perihelion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchand, R.; Miyake, Y.; Usui, H.

2014-06-15

Five spacecraft-plasma models are used to simulate the interaction of a simplified geometry Solar Probe Plus (SPP) satellite with the space environment under representative solar wind conditions near perihelion. By considering similarities and differences between results obtained with different numerical approaches under well defined conditions, the consistency and validity of our models can be assessed. The impact on model predictions of physical effects of importance in the SPP mission is also considered by comparing results obtained with and without these effects. Simulation results are presented and compared with increasing levels of complexity in the physics of interaction between solar environmentmore » and the SPP spacecraft. The comparisons focus particularly on spacecraft floating potentials, contributions to the currents collected and emitted by the spacecraft, and on the potential and density spatial profiles near the satellite. The physical effects considered include spacecraft charging, photoelectron and secondary electron emission, and the presence of a background magnetic field. Model predictions obtained with our different computational approaches are found to be in agreement within 2% when the same physical processes are taken into account and treated similarly. The comparisons thus indicate that, with the correct description of important physical effects, our simulation models should have the required skill to predict details of satellite-plasma interaction physics under relevant conditions, with a good level of confidence. Our models concur in predicting a negative floating potential V{sub fl}∼−10V for SPP at perihelion. They also predict a “saturated emission regime” whereby most emitted photo- and secondary electron will be reflected by a potential barrier near the surface, back to the spacecraft where they will be recollected.« less

Heat capacity mapping radiometer for AEM spacecraft

NASA Technical Reports Server (NTRS)

Sonnek, G. E.

1977-01-01

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

An update on the OpenOrbiter I Mission and its paradigm's benefits for the defense, homeland security and intelligence communities

NASA Astrophysics Data System (ADS)

Straub, Jeremy

2017-05-01

The OpenOrbiter I spacecraft is the culmination of significant work on reducing the cost levels of a CubeSat-class spacecraft. By redesigning the spacecraft from the ground up, down to the component level, to use readily available electronic and physical components, the cost of CubeSat construction has been significantly reduced. This paper provides an overview of the OpenOrbiter I mission, to date. It then focuses on the benefits that can be provided by the lower-cost, low-risk spacecraft. The paper discusses the prospective utility of this mission paradigm for the defense, homeland security and intelligence communities.

Open-systems Architecture of a Standardized Command Interface Chip-set for Switching and Control of a Spacecraft Power Bus

NASA Technical Reports Server (NTRS)

Ruiz, B. Ian; Burke, Gary R.; Lung, Gerald; Whitaker, William D.; Nowicki, Robert M.

2004-01-01

This viewgraph presentation reviews the architecture of the The CIA-AlA chip-set is a set of mixed-signal ASICs that provide a flexible high level interface between the spacecraft's command and data handling (C&DH) electronics and lower level functions in other spacecraft subsystems. Due to the open-systems architecture of the chip-set including an embedded micro-controller a variety of applications are possible. The chip-set was developed for the missions to the outer planets. The chips were developed to provide a single solution for both the switching and regulation of a spacecraft power bus. The Open-Systems Architecture allows for other powerful applications.

Prediction, Measurement, and Control of Spacecraft Charging Hazards on the International Space Station(ISS)

NASA Astrophysics Data System (ADS)

Koontz, Steve; Alred, John; Ellison, Amy; Patton, Thomas; Minow, Joseph; Spetch, William

2010-09-01

Orbital inclination, 51.6 degrees, and altitude range, 300 to 400 km,(low-Earth orbit or LEO) determine the ISS spacecraft charging environment. Specific interactions of the ISS electrical power system and metallic structure with the Earth’s ionospheric plasma and the geomagnetic field dominate spacecraft charging processes for ISS. ISS also flies through auroral electron streams at high latitudes. In this paper, we report the character of ISS spacecraft charging processes in Earth’s ionosphere, the results of measurement and modelling of the subject charging processes, and the safety issues for ISS itself as well as for ISS interoperability with respect to extra vehicular activity(EVA) and visiting vehicle proximity operations.

Replacing ODCs in a Critical Hand Cleaning Manual Electronics Assembly Operation

NASA Technical Reports Server (NTRS)

Bonner, J. K.; Walton, Sharon

1997-01-01

The manufacture of high reliability electronics assemblies for spacecraft and ground support equipment still often involves manual assembly processes. In addition, rework and repair of critical assemblies aslo often entails manual assembly processes.

Significance of Environmental Variables on Flight Electronics and Design Concerns for Extreme Environments

NASA Astrophysics Data System (ADS)

Hazeli, K.; Kingstedt, O. T.

2017-05-01

It is critical to investigate the performance of electronic systems and their components under the environments experienced during proposed missions to improve spacecraft and robotic vehicle functionality and performance in extreme environments.

The effect of electron collisions on rotational populations of cometary water

NASA Technical Reports Server (NTRS)

Xie, Xingfa; Mumma, Michael J.

1992-01-01

The e-H2O collisional rate for exciting rotational transitions in cometary water is evaluated for conditions found in Comet Halley during the Giotto spacecraft encounter. In the case of the 0(00)-1(11) rotational transition, the e-H2O collisional rate exceeds that for excitation by neutral-neutral collisions at distances exceeding 3000 km from the cometary nucleus. The estimates are based on theoretical and experimental studies of e-H2O collisions, on ion and electron parameters acquired in situ by instruments on the Giotto and Vega spacecraft, and on results obtained from models of the cometary ionosphere. Thus, the rotational temperature of the water molecule in the intermediate coma may be controlled by collisions with electrons rather than with neutral molecules, and the rotational temperature retrieved from high-resolution IR spectra of water in Comet Halley may reflect electron temperatures rather than neutral gas temperatures in the intermediate coma.

Charging/discharge events in coated spacecraft polymers during electron beam irradiation in a scanning electron microscope

NASA Astrophysics Data System (ADS)

Czeremuszkin, G.; Latrèche, M.; Wertheimer, M. R.

2001-12-01

Spacecraft, such as those operating in geosynchronous orbit (GEO), can be subjected to intense irradiation by charged particles, for example high-energy (e.g. 20 keV) electrons. The surfaces of dielectric materials (for example, polymers used as "thermal blankets") can therefore become potential sites for damaging electrostatic discharge (ESD) pulse events. We simulate these conditions by examining small specimens of three relevant polymers (polyimide, polyester and fluoropolymer), both bare and coated, in a scanning electron microscope (SEM). The coatings examined include commercial indium-tin oxide (ITO), and thin films of SiO 2 and a-Si:H deposited by plasma-enhanced chemical vapor deposition (PECVD). All coatings are found to greatly modify the observed ESD behavior, compared with that of the bare polymer counterparts. These observations are explained in terms of the model for ESD pulses proposed by Frederickson.

Previous design restraints and radiation damage effects of low energy particles

NASA Technical Reports Server (NTRS)

Trainor, J. H.

1972-01-01

Spacecraft design fluences and damage by low energy electrons and protons are summarized. For electron energies 5 MeV, the design fluence is 10 to the 11th power electrons/sq cm; for energies 5 MeV, the integral spectrum is assumed to go as 1/E sq. The design fluences for proton energies 30 MeV is 1.5 x 10 to the 9th power protons/sq cm; for energies 100 MeV, it is 5 x 10 to the 14th power protons/sq cm. The radioisotope thermoelectric generator gamma and neutron radiation constraints are listed. Damage due to electron energies 0.5 MeV and proton energies 10 MeV are summarized for effects on spacecraft thermal surfaces, reflective surfaces, and refractive materials. The high frequency noise figure for field effect transistors may increase markedly, and another effect is the buildup of charge on insulating surfaces, resulting in large electric fields.

Flag and Footprints Mission Mars: Preliminary Design Review Two

NASA Astrophysics Data System (ADS)

1998-01-01

SMI has developed a preliminary guideline for a flag and footprints manned mission to Mars. The manned mission is a split mission where the return and ground supplies will be sent on a cargo spacecraft. The crew spacecraft will leave on a high-energy trajectory once the cargo spacecraft has arrived in the prescribed orbit about Mars. The trajectory will be approximately 150-day from Low Earth Orbit (LEO) to the prescribed rendezvous orbit. The crew spacecraft will then dock with the orbiting cargo spacecraft for refuel and resupply. In addition, once safely docked, the crew members will transfer to the Mars Excursion Vehicle (MEV) for transport to the Martian surface. Each vehicle will be equipped with all necessary subsystems. To facilitate the transport of a large payload from Earth to Mars, the cargo spacecraft will utilize Ion propulsion. The Ion propulsion is ideal due to the high Isp characteristics. The crew spacecraft will be propelled with high-thrust RL-10 engines. Due to the smaller mass of the crew spacecraft, the spacecraft will utilize a 150-day high-energy trajectory. The MEV propulsion will be hypergolic. This choice of fuel is due to the reliability and simplicity of use. The crew members will stay on the surface of Mars for 30-days. During the 30-days, the crew will perform a series of scientific and exploratory experiments. To broaden the astronauts range of exploration, the astronauts will have access to three Unmanned Aerial Vehicles (UAV) and one rover while on the surface. The scientific experiments will consist of several soil and rock analyses as well as atmospheric study. Upon completion of the 30-day ground phase, the astronauts will return to the orbiting crew ship for return to Earth. SMI's flag and footprints mission outlines the fundamental systems and general requirements for these systems. SMI feels that with the fulfillment of these fundamental systems, this mission will be a highly desirable and potential candidate for development by NASA.

Development of a Spacecraft Materials Selector Expert System

NASA Technical Reports Server (NTRS)

Pippin, G.; Kauffman, W. (Technical Monitor)

2002-01-01

This report contains a description of the knowledge base tool and examples of its use. A downloadable version of the Spacecraft Materials Selector (SMS) knowledge base is available through the NASA Space Environments and Effects Program. The "Spacecraft Materials Selector" knowledge base is part of an electronic expert system. The expert system consists of an inference engine that contains the "decision-making" code and the knowledge base that contains the selected body of information. The inference engine is a software package previously developed at Boeing, called the Boeing Expert System Tool (BEST) kit.

Autonomy enables new science missions

NASA Astrophysics Data System (ADS)

Doyle, Richard J.; Gor, Victoria; Man, Guy K.; Stolorz, Paul E.; Chapman, Clark; Merline, William J.; Stern, Alan

1997-01-01

The challenge of space flight in NASA's future is to enable smaller, more frequent and intensive space exploration at much lower total cost without substantially decreasing mission reliability, capability, or the scientific return on investment. The most effective way to achieve this goal is to build intelligent capabilities into the spacecraft themselves. Our technological vision for meeting the challenge of returning quality science through limited communication bandwidth will actually put scientists in a more direct link with the spacecraft than they have enjoyed to date. Technologies such as pattern recognition and machine learning can place a part of the scientist's awareness onboard the spacecraft to prioritize downlink or to autonomously trigger time-critical follow-up observations-particularly important in flyby missions-without ground interaction. Onboard knowledge discovery methods can be used to include candidate discoveries in each downlink for scientists' scrutiny. Such capabilities will allow scientists to quickly reprioritize missions in a much more intimate and efficient manner than is possible today. Ultimately, new classes of exploration missions will be enabled.

Advanced optical sensing and processing technologies for the distributed control of large flexible spacecraft

NASA Technical Reports Server (NTRS)

Williams, G. M.; Fraser, J. C.

1991-01-01

The objective was to examine state-of-the-art optical sensing and processing technology applied to control the motion of flexible spacecraft. Proposed large flexible space systems, such an optical telescopes and antennas, will require control over vast surfaces. Most likely distributed control will be necessary involving many sensors to accurately measure the surface. A similarly large number of actuators must act upon the system. The used technical approach included reviewing proposed NASA missions to assess system needs and requirements. A candidate mission was chosen as a baseline study spacecraft for comparison of conventional and optical control components. Control system requirements of the baseline system were used for designing both a control system containing current off-the-shelf components and a system utilizing electro-optical devices for sensing and processing. State-of-the-art surveys of conventional sensor, actuator, and processor technologies were performed. A technology development plan is presented that presents a logical, effective way to develop and integrate advancing technologies.

Wide-Temperature Electronics for Thermal Control of Nanosats

NASA Technical Reports Server (NTRS)

Dickman, John Ellis; Gerber, Scott

2000-01-01

This document represents a presentation which examines the wide and low-temperature electronics required for NanoSatellites. In the past, larger spacecraft used Radioisotope Heating Units (RHU's). The advantage of the use of these electronics is that they could eliminate or reduce the requirement for RHU's, reduce system weight and simplify spacecraft design by eliminating containment/support structures for RHU's. The Glenn Research Center's Wide/Low Temperature Power Electronics Program supports the development of power systems capable of reliable, efficient operation over wide and low temperature ranges. Included charts review the successes and failures of various electronic devices, the IRF541 HEXFET, The NE76118n-Channel GaAS MESFET, the Lithium Carbon Monofluoride Primary Battery, and a COTS DC-DC converter. The preliminary result of wide/low temperature testing of CTS and custom parts and power circuit indicate that through careful selection of components and technologies it is possible to design and build power circuits which operate from room temperature to near 100K.

Solar corona electron density distribution

NASA Astrophysics Data System (ADS)

Esposito, P. B.; Edenhofer, P.; Lueneburg, E.

1980-07-01

The paper discusses the three and one-half months of single-frequency time delay data which were acquired from the Helios 2 spacecraft around the time of its solar occultation. The excess time delay due to integrated effect of free electrons along the signal's ray path could be separated and modeled following the determination of the spacecraft trajectory. An average solar corona and equatorial electron density profile during solar minimum were deduced from the time delay measurements acquired within 5-60 solar radii of the sun. As a point of reference at 10 solar radii from the sun, an average electron density was 4500 el/cu cm. However, an asymmetry was found in the electron density as the ray path moved from the west to east solar limb. This may be related to the fact that during entry into occultation the heliographic latitude of the ray path was about 6 deg, while during exit it was 7 deg. The Helios density model is compared with similar models deduced from different experimental techniques.

Electron Emission Properties of Insulator Materials Pertinent to the International Space Station

NASA Technical Reports Server (NTRS)

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

2004-01-01

We present the results of our measurements of the electron emission properties of selected insulating and conducting materials used on the International Space Station (ISS). Utah State University (USU) has performed measurements of the electron-, ion-, and photon-induced electron emission properties of conductors for a few years, and has recently extended our capabilities to measure electron yields of insulators, allowing us to significantly expand current spacecraft material charging databases. These ISS materials data are used here to illustrate our various insulator measurement techniques that include: i) Studies of electron-induced secondary and backscattered electron yield curves using pulsed, low current electron beams to minimize deleterious affects of insulator charging. ii) Comparison of several methods used to determine the insulator 1st and 2nd crossover energies. These incident electron energies induce unity total yield at the transition between yields greater than and less than one with either negative or positive charging, respectively. The crossover energies are very important in determining both the polarity and magnitude of spacecraft surface potentials. iii) Evolution of electron emission energy spectra as a function of insulator charging used to determine the surface potential of insulators. iv) Surface potential evolution as a function of pulsed-electron fluence to determine how quickly insulators charge, and how this can affect subsequent electron yields. v) Critical incident electron energies resulting in electrical breakdown of insulator materials and the effect of breakdown on subsequent emission, charging and conduction. vi) Charge-neutralization techniques such as low-energy electron flooding and UV light irradiation to dissipate both positive and negative surface potentials during yield measurements. Specific ISS materials being tested at USU include chromic and sulfuric anodized aluminum, RTV-silicone solar array adhesives, solar cell cover glasses, Kapton, and gold. Further details of the USU testing facilities, the instrumentation used for insulator measurements, and the NASA/SEE Charge Collector materials database are provided in other Spacecraft Charging Conference presentations (Dennison, 2003b). The work presented was supported in part by the NASA Space Environments and Effects (SEE) Program, the Boeing Corporation, and a NASA Graduate Fellowship. Samples were supplied by Boeing, the Environmental Effects Group at Marshall Space Flight Center, and Sheldahl, Inc.

RELEC Mission: Relativistic Electron Precipitation and TLE study on-board small spacecraft

NASA Astrophysics Data System (ADS)

Svertilov, Sergey

The main goal of RELEC mission is studying of magnetosphere relativistic electron precipitation and its acting on the upper Atmosphere as well as transient luminous events (TLE) observation in wide range of electromagnetic spectrum. The RELEC set of instruments includes two identical detectors of X- and gamma-rays of high temporal resolution and sensitivity (DRGE-1 & DRGE-2), three axe directed detectors of energetic electrons and protons DRGE-3, UV TLE imager MTEL, UV detector DUV, low-frequency analyser LFA, radio-frequency analyser RFA, module of electronics intended for commands and data collection BE. During the RELEC mission following experiments will be provided: - simultaneous observations of energetic electron & proton flux (energy range ~0.1-10.0 MeV and low-frequency (~0.1-10 kHz) electromagnetic wave field intensity variations with high temporal resolution (~1 ms); - fine time structure (~1 mcs) measurements of transient atmospheric events in UV, X- and gamma rays with a possibility of optical imaging with resolution of ~km in wide FOV; - measurements of electron flux pitch-angle distribution in dynamical range from ~0.1 up to 105 part/cm2s; - monitoring of charge and neutral background particles in different areas of near-Earth space. Now the all RELEC instruments are installed on-board small spacecraft manufactured by Lavochkin space corporation. The launch is scheduled on May, 2014 as by-pass mission with Meteor spacecraft. The RELEC mission orbit is planned to be quasi-circular solar-synchronous with about 700 km height. The total volume of transmitted data is about 1.2 Gbyte per day.

The coronal electron density distribution determined from dual-frequency ranging measurements during the 1991 solar conjunction of the Ulysses spacecraft

NASA Technical Reports Server (NTRS)

Bird, M. K.; Volland, H.; Paetzold, M.; Edenhofer, P.; Asmar, S. W.; Brenkle, J. P.

1994-01-01

Dual-frequency ranging and Doppler measurements were conducted in support of the Ulysses Solar Corona Experiment (SCE) at and around the spacecraft's first solar conjunction in 1991 August. The differential group delay time between range codes on the two downlink carrier signals at the wavelengths 13.1 and 3.6 cm, a direct measure of the total electron content between spacecraft and ground station, was used to derive the electron density distribution in the solar corona. Linear power-law representations of the coronal electron density were derived for the range of solar distances from 4 solar radii to 40 solar radii on both sides of the Sun. The corona was found to be very nearly symmetric; the radial falloff exponent being 2.54 +/- 0.05 for occultation ingress (east solar limb) and 2.42 +/- 0.05 for egress (west limb), respectively. The departure of these exponents from the inverse equare relation implies that significant solar wind acceleration is occurring within the radial range of the observations. The electron density level was found to be considerably lower than that observed during the 1988 December solar occultation of Voyager 2. Although the smoothed sunspot number R(sub z) (a standard indicator of solar activity) was almost the same in 1988 December and 1991 August, the mean electron density at 20 solar radii was found to be 1.7 +/- 0.1 x 10(exp 3)/cu cm during the Ulysses conjunction, a decline by almost a factor of 4 from the value obtained during the Voyager conjunction.

Telecommunications in cometary environments

NASA Technical Reports Server (NTRS)

Flock, W. L.

1981-01-01

Propagation effects on telecommunications in a cometary environment include those due to dust, the inhomogeneous plasma of the coma and tail, and ionization generated by impact of neutral molecules and dust on the spacecraft. Attenuation caused by dust particles is estimated to be on the order of 10 to the minus 5th power dB for the Halley Intercept Mission. Ionization generated by impact on the spacecraft is estimated to result in an electron content of 10 to the 12th power to 10 to the 13th power el/sq meters (3 eV electrons) along the telecommunications path. An estimate of the electron content due to Comet Halley itself is 10 to the 16th power to 10 to the 17th power el/sq meters, compared to a content of 10 to the 16th power to 10 to the 18th power el/sq meters for the Earth's ionosphere and 10 to the 17th power to 10 to the 18th power el/sq meters for the interplanetary medium. The electron content of the plasma near Comet Halley will cause excess range delay, and a Doppler shift of the signal from the spacecraft will occur in propagation to the rate of change of the path electron content. It is recommended that S and X down-link frequencies by employed to monitor the path electron content and amplitude scintillation and spectral broadening of the received signals. These measurements will provide a quantitative base of knowledge that will be valuable for radio science and telecommunications system design purposes.

Autonomous spacecraft attitude control using magnetic torquing only

NASA Technical Reports Server (NTRS)

Musser, Keith L.; Ebert, Ward L.

1989-01-01

Magnetic torquing of spacecraft has been an important mechanism for attitude control since the earliest satellites were launched. Typically a magnetic control system has been used for precession/nutation damping for gravity-gradient stabilized satellites, momentum dumping for systems equipped with reaction wheels, or momentum-axis pointing for spinning and momentum-biased spacecraft. Although within the small satellite community there has always been interest in expensive, light-weight, and low-power attitude control systems, completely magnetic control systems have not been used for autonomous three-axis stabilized spacecraft due to the large computational requirements involved. As increasingly more powerful microprocessors have become available, this has become less of an impediment. These facts have motivated consideration of the all-magnetic attitude control system presented here. The problem of controlling spacecraft attitude using only magnetic torquing is cast into the form of the Linear Quadratic Regulator (LQR), resulting in a linear feedback control law. Since the geomagnetic field along a satellite trajectory is not constant, the system equations are time varying. As a result, the optimal feedback gains are time-varying. Orbit geometry is exploited to treat feedback gains as a function of position rather than time, making feasible the onboard solution of the optimal control problem. In simulations performed to date, the control laws have shown themselves to be fairly robust and a good candidate for an onboard attitude control system.

Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations

NASA Astrophysics Data System (ADS)

Chen, L.-J.; Hesse, M.; Wang, S.; Gershman, D.; Ergun, R. E.; Burch, J.; Bessho, N.; Torbert, R. B.; Giles, B.; Webster, J.; Pollock, C.; Dorelli, J.; Moore, T.; Paterson, W.; Lavraud, B.; Strangeway, R.; Russell, C.; Khotyaintsev, Y.; Lindqvist, P.-A.; Avanov, L.

2017-05-01

An electron diffusion region (EDR) in magnetic reconnection with a guide magnetic field approximately 0.2 times the reconnecting component is encountered by the four Magnetospheric Multiscale spacecraft at the Earth's magnetopause. The distinct substructures in the EDR on both sides of the reconnecting current sheet are visualized with electron distribution functions that are 2 orders of magnitude higher cadence than ever achieved to enable the following new findings: (1) Motion of the demagnetized electrons plays an important role to sustain the reconnection current and contributes to the dissipation due to the nonideal electric field, (2) the finite guide field dominates over the Hall magnetic field in an electron-scale region in the exhaust and modifies the electron flow dynamics in the EDR, (3) the reconnection current is in part carried by inflowing field-aligned electrons in the magnetosphere part of the EDR, and (4) the reconnection electric field measured by multiple spacecraft is uniform over at least eight electron skin depths and corresponds to a reconnection rate of approximately 0.1. The observations establish the first look at the structure of the EDR under a weak but not negligible guide field.

Radiation shielding for future space exploration missions

NASA Astrophysics Data System (ADS)

DeWitt, Joel Michael

Scope and Method of Study. The risk to space crew health and safety posed by exposure to space radiation is regarded as a significant obstacle to future human space exploration. To countermand this risk, engineers and designers in today's aerospace community will require detailed knowledge of a broad range of possible materials suitable for the construction of future spacecraft or planetary surface habitats that provide adequate protection from a harmful space radiation environment. This knowledge base can be supplied by developing an experimental method that provides quantitative information about a candidate material's space radiation shielding efficacy with the understanding that (1) shielding is currently the only practical countermeasure to mitigate the effects of space radiation on human interplanetary missions, (2) any mass of a spacecraft or planetary surface habitat necessarily alters the incident flux of ionizing radiation on it, and (3) the delivery of mass into LEO and beyond is expensive and therefore may benefit from the possible use of novel multifunctional materials that could in principle reduce cost as well as ionizing radiation exposure. The developed method has an experimental component using CR-39 PNTD and Al2O3:C OSLD that exposes candidate space radiation shielding materials of varying composition and depth to a representative sample of the GCR spectrum that includes 1 GeV 1H and 1 GeV/n 16O, 28Si, and 56Fe heavy ion beams at the BNL NSRL. The computer modeling component of the method used the Monte Carlo radiation transport code FLUKA to account for secondary neutrons that were not easily measured in the laboratory. Findings and Conclusions. This study developed a method that quantifies the efficacy of a candidate space radiation shielding material relative to the standard of polyethylene using a combination of experimental and computer modeling techniques. The study used established radiation dosimetry techniques to present an empirical weighted figure of merit (WFoM) approach that quantifies the effectiveness of a candidate material to shield space crews from the whole of the space radiation environment. The results of the WFoM approach should prove useful to designers and engineers in seeking alternative materials suitable for the construction of spacecraft or planetary surface habitats needed for long-term space exploration missions. The dosimetric measurements in this study have confirmed the principle of good space radiation shielding design by showing that low-Z¯ materials are most effective at reducing absorbed dose and dose equivalent while high-Z¯ materials are to be avoided. The relatively high WFoMs of carbon composite and lunar- and Martian-regolith composite could have important implications for the design and construction of future spacecraft or planetary surface habitats. The ground-based measurements conducted in this study have validated the heavy ion extension of FLUKA by producing normalized differential LET fluence spectra that are in good agreement with experiment.

Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

NASA Technical Reports Server (NTRS)

Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

1973-01-01

With missions to Jupiter, the spacecraft will be exposed for extended durations to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine spore-forming and three non-spore-forming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2, 12, and 25 MeV electrons at different doses with simultaneous exposure to a vacuum of 1.3 x 10(-4) N m-2 at 20 and -20 degrees C. The radioresistance of the subpopulation was dependent on the isolate, dose and energy of electrons. Temperature affected the radioresistance of only the spore-forming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J kg-1 (10 J kg-1=1 krad), while non-spore-forming isolates (micrococci) were reduced 1.5-2 logs/1500 J kg-1 with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons. The bacterial isolates were exposed to 3 keV protons under the same conditions as the electrons with a total fluence of 1.5 x 10(13) p cm-2 and a dose rate of 8.6 x 10(9) p cm-2 s-1. The results showed that only 20% of S. epidermidis and 45% of B. subtilis populations survived exposure to the 3 keV protons, while the mean survival of the spacecraft subpopulation was 45% with a range from 31.8% (non-spore-former) to 64.8% (non-spore-former). No significant difference existed between spore-forming and non-spore-forming isolates.

Precipitating auroral electrons and lower thermospheric nitric oxide densities: SNOE, POLAR, SAMPEX, and NOAA/POES Comparisons for Geomagnetic Storms in 1998-2001

NASA Astrophysics Data System (ADS)

Baker, D. N.; Fisher, T. A.; Barth, C. A.; Mankoff, K. D.; Kanekal, S. G.; Bailey, S. M.; Petrinec, S. M.; Luhmann, J. G.; Mason, G. M.; Mazur, J. E.; Evans, D. S.

2002-05-01

Nitric oxide (NO) densities measured at altitudes between 97 and 150 km have been acquired using the UVS sensor onboard the Student Nitric Oxide Explorer (SNOE) spacecraft during the years 1998-2001. These data are compared with energetic electron fluxes (E>25 keV) measured concurrently using a sensitive sensor system (LICA) onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) spacecraft. Geomagnetic storm intervals are examined to determine altitude and latitude variations of NO density as it compares to energetic electron precipitation. A broader statistical analysis is then carried out using daily averages of peak NO densities (at 106 km altitudes) and electron intensities measured by SAMPEX/LICA and by the TED sensor system onboard the NOAA/Polar Orbiting Environmental Satellite (POES) spacecraft. We also use the PIXIE instrument onboard POLAR to obtain global views of 2-12 keV x-rays emanating from the upper atmosphere. This gives a broad synoptic measure of relatively low-energy electron precipitation into the atmosphere. Latitude versus time displays of the UVS, PIXIE, LICA and TED data show excellent temporal and spatial correlations of the data sets. More detailed comparisons help us to assess spectral and local time relationships between auroral particle inputs and lower thermospheric chemical responses. These results are potentially quite important since past modeling has shown that particle inputs are significant for changing the chemistry and subsequent dynamics of the atmosphere.

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

NASA Technical Reports Server (NTRS)

Westphal, A. J.; Allen, C.; Ansari, A.; Bajt, S.; Bastien, R. S.; Bassim, N.; Bechtel, H. A.; Borg, J.; Brenker, F. E.; Bridges, J.;

Orion Exploration Flight Test Post-Flight Inspection and Analysis

NASA Technical Reports Server (NTRS)

Miller, J. E.; Berger, E. L.; Bohl, W. E.; Christiansen, E. L.; Davis, B. A.; Deighton, K. D.; Enriquez, P. A.; Garcia, M. A.; Hyde, J. L.; Oliveras, O. M.

2017-01-01

The principal mechanism for developing orbital debris environment models, is to make observations of larger pieces of debris in the range of several centimeters and greater using radar and optical techniques. For particles that are smaller than this threshold, breakup and migration models of particles to returned surfaces in lower orbit are relied upon to quantify the flux. This reliance on models to derive spatial densities of particles that are of critical importance to spacecraft make the unique nature of the EFT-1's return surface a valuable metric. To this end detailed post-flight inspections have been performed of the returned EFT-1 backshell, and the inspections identified six candidate impact sites that were not present during the pre-flight inspections. This paper describes the post-flight analysis efforts to characterize the EFT-1 mission craters. This effort included ground based testing to understand small particle impact craters in the thermal protection material, the pre- and post-flight inspection, the crater analysis using optical, X-ray computed tomography (CT) and scanning electron microscope (SEM) techniques, and numerical simulations.

Wheel configurations for combined energy storage and attitude control systems

NASA Technical Reports Server (NTRS)

Oglevie, R. E.

1985-01-01

Integrated power and attitude control system (IPACS) studies performed over a decade ago established the feasibility of simultaneously storing electrical energy in wheels and utilizing the resulting momentum for spacecraft attitude control. It was shown that such a system possessed many advantages over other contemporary energy storage and attitude control systems in many applications. More recent technology advances in composite rotors, magnetic bearings, and power control electronics have triggered new optimism regarding the feasibility and merits of such a system. This paper presents the results of a recent study whose focus was to define an advanced IPACS and to evaluate its merits for the Space Station application. Emphasis is given to the selection of the wheel configuration to perform the combined functions. A component design concept is developed to establish the system performance capability. A system-level trade study, including life-cycle costing, is performed to define the merits of the system relative to two other candidate systems. It is concluded that an advanced IPACS concept is not only feasible but offers substantial savings in mass and life-cycle cost.

Quantifying the Spatial and Temporal Properties of Microbursts with Multi-spacecraft Missions

NASA Astrophysics Data System (ADS)

Shumko, M.; Turner, D. L.; Sample, J. G.; O'Brien, T. P., III; Claudepierre, S. G.; Fennell, J. F.; Johnson, A.; Blake, J. B.; Agapitov, O. V.; Crew, A. B.; Klumpar, D. M.; Spence, H. E.

2017-12-01

The outer electron Van Allen radiation belt is highly variable, and is at times, depleted on the order of one day or less. One loss mechanism potentially capable of depleting the belts on such timescales is electron microbursts, a sporadic and sudden burst of electrons, routinely observed in Low Earth Orbit (LEO). To quantify their contribution to radiation belt electron loss, their spatio-temporal morphology must be well characterized and constrained. These properties can be investigated by multi-spacecraft missions e.g. Focused Investigations of Relativistic Electron Burst Intensity, Range, and Dynamics (FIREBIRD-II), AeroCube 6 (AC6) and the Van Allen Probes (VAP). We present results of microburst scale sizes derived using FIREBIRD-II and AC-6 CubeSats pairs. In addition, we present results of a conjunction between AC6 and VAP at L 5. Lower band chorus was observed by the EMFISIS instrument, while microbursts were observed with its MagEIS instrument, and AC6 in LEO. We believe that this MagEIS observation is the first known measurement of an electron microburst outside of LEO.

Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hao, Y. X.; Zong, Q. -G.; Zhou, X. -Z.

Here, we present an analysis of “boomerang-shaped” pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact withmore » electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.« less

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

NASA Technical Reports Server (NTRS)

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

1980-01-01

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

Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions

NASA Astrophysics Data System (ADS)

Hao, Y.; Zong, Q.; Zhou, X.; Rankin, R.; Chen, X.; Liu, Y.; Fu, S.; Spence, H. E.; Blake, J. B.; Reeves, G. D.

2017-12-01

We present an analysis of "boomerang-shaped" pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on June 7th, 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90º pitch angle electrons, the phase change of the flux modulations across energy exceeds 180º, and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wave field reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift-resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.

Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions

NASA Astrophysics Data System (ADS)

Hao, Y. X.; Zong, Q.-G.; Zhou, X.-Z.; Rankin, R.; Chen, X. R.; Liu, Y.; Fu, S. Y.; Spence, H. E.; Blake, J. B.; Reeves, G. D.

2017-08-01

We present an analysis of "boomerang-shaped" pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact with electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.

Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions

DOE PAGES

Hao, Y. X.; Zong, Q. -G.; Zhou, X. -Z.; ...

2017-07-10

Here, we present an analysis of “boomerang-shaped” pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on 7 June 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90° pitch angle electrons, the phase change of the flux modulations across energy exceeds 180° and increasingly tilts with time. Using estimates of the arrival time of particles of different pitch angles at the spacecraft location, a scenario is investigated in which shock-induced ULF waves interact withmore » electrons through the drift resonance mechanism in a localized region westward of the spacecraft. Numerical calculations on particle energy gain with the modified ULF wavefield reproduce the observed boomerang stripes and modulations in the electron energy spectrogram. The study of boomerang stripes and their relationship to drift resonance taking place at a location different from the observation point adds new understanding of the processes controlling the dynamics of the outer radiation belt.« less

The effects of the geosynchronous energetic particle radiation environment on spacecraft charging phenomena

NASA Technical Reports Server (NTRS)

Reagan, J. B.; Imhof, W. L.; Gaines, E. E.

1977-01-01

The energetic electron environment at the geosynchronous orbit is responsible for a variety of adverse charging effects on spacecraft components. The most serious of these is the degradation and failure of a complementary-metal-oxide-semiconductor (CMOS) electronic components as a result of internal charge-buildup induced by the energetic electrons. Efforts to accurately determine the expected lifetime of these components in this orbit are hampered by the lack of detailed knowledge of the electron spectrum and intensity, particularly of the more penetrating energies greater than 1.5 MeV. This problem is illustrated through the calculation of the dose received by a CMOS device from the energetic electrons and associated bremsstrahlung as a function of aluminum shielding thickness using the NASA AE-6 and the Aerospace measured electron environments. Two computational codes which were found to be in good agreement were used to perform the calculations. For a given shielding thickness the dose received with the two radiation environments differ by as much as a factor of seven with a corresponding variation in lifetime of the CMOS.

Fast Plasma Instrument for MMS: Data Compression Simulation Results

NASA Astrophysics Data System (ADS)

Barrie, A.; Adrian, M. L.; Yeh, P.; Winkert, G.; Lobell, J.; Vinas, A. F.; Simpson, D. G.

2009-12-01

Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6° x 180° fields-of-view (FOV) are set 90° apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45° x 180° fan about the its nominal viewing (0° deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb s-1 of electron data while the DIS generates 1.1-Mb s-1 of ion data yielding an FPI total data rate of 6.6-Mb s-1. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. Currently, the FPI data rate allocation to the CIDP is 1.5-Mb s-1. Consequently, the FPI-IDPU must employ data/image compression to meet this CIDP telemetry allocation. Here, we present updated simulations of the CCSDS 122.0-B-1 algorithm-based compression of the FPI-DES electron data as well as the FPI-DIS ion data. Compression analysis is based upon a seed of re-processed Cluster/PEACE electron measurements and Cluster/CIS ion measurements. Topics to be discussed include: (i) Review of compression algorithm; (ii) Data quality; (iii) Data formatting/organization; (iv) Compression optimization; (v) Investigation of pseudo-log precompression; and (vi) Analysis of compression effectiveness for burst mode as well as fast survey mode data packets for both electron and ion data We conclude with a presentation of the current base-lined FPI data compression approach.

CeREs_VCLS_CubeSat_0002

NASA Image and Video Library

2018-04-10

A host of CubeSats, or small satellites, are undergoing the final stages of processing at Rocket Lab USA’s facility in Huntington Beach, California, for NASA’s first mission dedicated solely to spacecraft of their size. This will be the first launch under the agency’s new Venture Class Launch Services. Scientists, including those from NASA and various universities, began arriving at the facility in early April with spacecraft small enough to be a carry-on to be prepared for launch. A team from NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, completed final checkouts of a CubeSat called the Compact Radiation Belt Explorer (CeREs), before placing the satellite into a dispenser to hold the spacecraft during launch inside the payload fairing. Among its missions, the satellite will examine the radiation belt and how electrons are energized and lost, particularly during events called microbursts — when sudden swarms of electrons stream into the atmosphere. This facility is the final stop for designers and builders of the CubeSats, but the journey will continue for the spacecraft. Rocket Lab will soon ship the satellites to New Zealand for launch aboard the company’s Electron orbital rocket on the Mahia Peninsula this summer. The CubeSats will be flown on an Educational Launch of Nanosatellites (ELaNa) mission to space through NASA’s CubeSat Launch Initiative. CeREs is one of the 10 ELaNa CubeSats scheduled to be a part of this mission.

Development of hydrogen peroxide technique for bioburden reduction

NASA Astrophysics Data System (ADS)

Rohatgi, N.; Schwartz, L.; Stabekis, P.; Barengoltz, J.

In order to meet the National Aeronautics and Space Administration (NASA) Planetary Protection microbial reduction requirements for Mars in-situ life detection and sample return missions, entire planetary spacecraft (including planetary entry probes and planetary landing capsules) may have to be exposed to a qualified sterilization process. Presently, dry heat is the only NASA approved sterilization technique available for spacecraft application. However, with the increasing use of various man-made materials, highly sophisticated electronic circuit boards, and sensors in a modern spacecraft, compatibility issues may render this process unacceptable to design engineers and thus impractical to achieve terminal sterilization of the entire spacecraft. An alternative vapor phase hydrogen peroxide sterilization process, which is currently used in various industries, has been selected for further development. Strategic Technology Enterprises, Incorporated (STE), a subsidiary of STERIS Corporation, under a contract from the Jet Propulsion Laboratory (JPL) is developing systems and methodologies to decontaminate spacecraft using vaporized hydrogen peroxide (VHP) technology. The VHP technology provides an effective, rapid and low temperature means for inactivation of spores, mycobacteria, fungi, viruses and other microorganisms. The VHP application is a dry process affording excellent material compatibility with many of the components found in spacecraft such as polymers, paints and electronic systems. Furthermore, the VHP process has innocuous residuals as it decomposes to water vapor and oxygen. This paper will discuss the approach that is being used to develop this technique and will present lethality data that have been collected to establish deep vacuum VHP sterilization cycles. In addition, the application of this technique to meet planetary protection requirements will be addressed.

Instrument and spacecraft faults associated with nuclear radiation in space

NASA Technical Reports Server (NTRS)

Trainos, J. H.

1994-01-01

A review is given which surveys the variety of faults and failures which have occurred in space due both to the effects of single, energetic nuclear particles, as well as effects due to the accumulated ionizing dose or the fluence of nuclear particles. The review covers a variety of problems with sensors, electronics, instruments and spacecraft from several countries.

Accelerated life testing of spacecraft subsystems

NASA Technical Reports Server (NTRS)

Wiksten, D.; Swanson, J.

1972-01-01

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

Experimental Studies of Spray Deposition on a Flat Surface in a Vacuum Environment

NASA Technical Reports Server (NTRS)

Golliher, Eric L.; Yao, S. C.

2015-01-01

Cooling of spacecraft components in the space environment is an on-going research effort. The electronics used in modern spacecraft are always changing and the heat flux is increasing. New, one-of-a-kind missions require new approaches to thermal control. In this research, under vacuum conditions, a pulsed water spray impinged on a small disc, while a high speed data acquisition system recorded the temperature histories of this copper disc. The water droplets froze quickly and accumulated on the disc as the spray continued. After the spray stopped, the frozen water that remained on the disc then sublimated into the vacuum environment and cooled the disc. This paper examines two important aspects of this process: 1) the difference in spray start up and shutdown in a vacuum environment versus in a standard atmospheric pressure environment, and 2) the water utilization efficiency in a vacuum environment due to the effects of drop trajectories and drop bouncing on the surface. Both phenomena play a role during spray cooling in a vacuum. This knowledge should help spacecraft designers plan for spray cooling as an option to cool spacecraft electronics, human metabolic generated heat, and heat from other sources.

The Potential and Equipotentiality of Spacecraft

NASA Astrophysics Data System (ADS)

Afonin, V. V.

2004-01-01

The problem of maintenance of the equipotentiality of spacecraft surfaces is considered. The method under examination is the use of the ``conductive thermal-vacuum multilayer blanket'' (CMLB), whose outer surface represents a fabric woven of threads of glass fiber type with interwoven metal threads. The process of spacecraft potential formation and methods of the potential calculation are described, and the results of such a calculation for the illuminated and shadowed parts of spacecraft surfaces in some characteristic near-Earth plasma environments are presented. The CMLB model is described, and the potential distribution near the CMLB surface is calculated. The conclusion was drawn that the conductive thermal-vacuum multilayer blanket used in some cases on Russian spacecraft does not ensure the equipotentiality of spacecraft surfaces, and in the case of using CMLB, the differential spacecraft charging in outer regions of the Earth's magnetosphere may reach a dangerous level for onboard electronic systems. In spite of the fact that CMLB guards against large-scale powerful discharges, one cannot exclude discharges completely, what may result in broadband noise enhancement and cause onboard systems failures.

Ion acoustic waves in the solar wind

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Frank, L. A.

1978-01-01

Plasma wave measurements on the Helios 1 and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are shortwavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic wave turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered.

Trajectory selection for the Mariner Jupiter/Saturn 1977 project

NASA Technical Reports Server (NTRS)

Dyer, J. S.; Miles, R. F., Jr.

1974-01-01

The use of decision analysis to facilitate a group decision-making problem in the selection of trajectories for the two spacecraft of the Mariner Jupiter/Saturn 1977 Project. A set of 32 candidate trajectory pairs was developed. Cardinal utility function values were assigned to the trajectory pairs, and the data and statistics derived from collective choice rules were used in selecting the science-preferred trajectory pair.

A survey of candidate missions to explore Saturn's rings

NASA Technical Reports Server (NTRS)

Wells, W. C.; Price, M. J.

1972-01-01

The ring system around Saturn is discussed. Exploration of the rings is required for an understanding of their origin and the hazard they represent to spacecraft near Saturn. In addition the rings may provide useful clues to the origin of the solar system. This study examines the problem of ring system exploration and recommends a sequence of missions which will collect the data required.

Design and Evaluation of Candidate Pressure Distribution and Air Data System Tile Penetration for the Aeroassist Flight Experiment

NASA Technical Reports Server (NTRS)

Vontheumer, Alfred E.

1990-01-01

This program objectives were to produce a pressure measurements system that penetrates the thermal protection system of a spacecraft and is able to obtain accurate pressure data. The design was tested vibro-acoustically, aerothermally, and structurally and found to be adequate. This design is a possible replacement of the current pressure system on the orbiter.

Statistical evaluation of vibration analysis techniques

NASA Technical Reports Server (NTRS)

Milner, G. Martin; Miller, Patrice S.

1987-01-01

An evaluation methodology is presented for a selection of candidate vibration analysis techniques applicable to machinery representative of the environmental control and life support system of advanced spacecraft; illustrative results are given. Attention is given to the statistical analysis of small sample experiments, the quantification of detection performance for diverse techniques through the computation of probability of detection versus probability of false alarm, and the quantification of diagnostic performance.

Electrostatic solitary waves in current layers: from Cluster observations during a super-substorm to beam experiments at the LAPD

NASA Astrophysics Data System (ADS)

Pickett, J. S.; Chen, L.-J.; Santolík, O.; Grimald, S.; Lavraud, B.; Verkhoglyadova, O. P.; Tsurutani, B. T.; Lefebvre, B.; Fazakerley, A.; Lakhina, G. S.; Ghosh, S. S.; Grison, B.; Décréau, P. M. E.; Gurnett, D. A.; Torbert, R.; Cornilleau-Wehrlin, N.; Dandouras, I.; Lucek, E.

2009-06-01

Electrostatic Solitary Waves (ESWs) have been observed by several spacecraft in the current layers of Earth's magnetosphere since 1982. ESWs are manifested as isolated pulses (one wave period) in the high time resolution waveform data obtained on these spacecraft. They are thus nonlinear structures generated out of nonlinear instabilities and processes. We report the first observations of ESWs associated with the onset of a super-substorm that occurred on 24 August 2005 while the Cluster spacecraft were located in the magnetotail at around 18-19 RE and moving northward from the plasma sheet to the lobes. These ESWs were detected in the waveform data of the WBD plasma wave receiver on three of the Cluster spacecraft. The majority of the ESWs were detected about 5 min after the super-substorm onset during which time 1) the PEACE electron instrument detected significant field-aligned electron fluxes from a few 100 eV to 3.5 keV, 2) the EDI instrument detected bursts of field-aligned electron currents, 3) the FGM instrument detected substantial magnetic fluctuations and the presence of Alfvén waves, 4) the STAFF experiment detected broadband electric and magnetic waves, ion cyclotron waves and whistler mode waves, and 5) CIS detected nearly comparable densities of H+ and O+ ions and a large tailward H+ velocity. We compare the characteristics of the ESWs observed during this event to those created in the laboratory at the University of California-Los Angeles Plasma Device (LAPD) with an electron beam. We find that the time durations of both space and LAPD ESWs are only slightly larger than the respective local electron plasma periods, indicating that electron, and not ion, dynamics are responsible for generation of the ESWs. We have discussed possible mechanisms for generating the ESWs in space, including the beam and kinetic Buneman type instabilities and the acoustic instabilities. Future studies will examine these mechanisms in more detail using the space measurements as inputs to models, and better relate the ESW space measurements to the laboratory through PIC code models.

Inner magnetospheric electron temperature and spacecraft potential estimated from concurrent Polar upper hybrid frequency and relative potential measurements

NASA Astrophysics Data System (ADS)

Boardsen, S. A.; Adrian, M. L.; Pfaff, R.; Menietti, J. D.

2014-10-01

Direct measurement of low < 1 eV electron temperature is difficult to make in the Earth's inner magnetosphere for electron densities (Ne) < 3 × 102 cm-3. We compute these quantities by solving current balance equations in low-density regions. Concurrent measurements from the Polar spacecraft of the relative potential (VS - VP), between the spacecraft body and the electric field probe, and the electron density (Ne), derived from upper hybrid frequency (fUHR), were used in the current balance equations to solve for the electron temperature (Te), Vs, and Vp. Where VP is the probe potential and VS is the spacecraft potential relative to the nearby plasma. The assumption that the bulk plasma electrons are Maxwellian is used in the computations. Our data set covered 1.5 years of measurements when fUHR was detectable (L < 10). The following "averaged" Te versus L relation for 3 < L < 5 was obtained: Te = 0.58 + 0.49 (L - 3) eV. This expression is in reasonable agreement with extrapolations of ionospheric Te measurements by Akebono at lower altitudes. However, the solution is sensitive to the photoemission coefficients, substituting those of Scudder et al. (2000) with those of Escoubet et al. (1997), the Te curve shifted upward by ~1 eV. Also, the solution is sensitive to measurement error of VS - VP, applying a voltage shift of ±0.1 and ±0.2 V to VS - VP, the relative median error for our data set was computed to be 0.27 and 1.04, respectively. We believe that our Te values computed outside the plasmasphere are unrealistically low. We conclude that this method shows promise inside the plasmasphere but should be used with caution. We also quantified the Ne versus VS - VP relationship. The running median Ne versus VS - VP curve shows no significant variation over the 1.5 year period of the data set, suggesting that the photoemission coefficients did not change significantly over this time span. The Scudder et al. (2000) Ne model, based on only one Polar orbit, is in reasonable agreement (within a factor of 2) with our results.

Measuring the spacecraft and environmental interactions of the 8-cm mercury ion thrusters on the P80-1 mission

NASA Technical Reports Server (NTRS)

Power, J. L.

1981-01-01

The subject interface measurements are described for the Ion Auxiliary Propulsion System (IAPS) flight test of two 8-cm thrusters. The diagnostic devices and the effects to be measured include: 1) quartz crystal microbalances to detect nonvolatile deposition due to thruster operation; 2) warm and cold solar cell monitors for nonvolatile and volatile (mercury) deposition; 3) retarding potential ion collectors to characterize the low energy thruster ionic efflux; and 4) a probe to measure the spacecraft potential and thruster generated electron currents to biased spacecraft surfaces. The diagnostics will also assess space environmental interactions of the spacecraft and thrusters. The diagnostic data will characterize mercury thruster interfaces and provide data useful for future applications.

(abstract) Follow-on Missions for the Pluto Spacecraft

NASA Technical Reports Server (NTRS)

Weinstein, Stacy; Salvo, Chris; Stern, Alan

1994-01-01

The Pluto Fast Flyby mission development baseline consists of 2 identical spacecraft (120 - 165 kg) to be launched to Pluto/Charon in the late 1990s. These spacecraft are intended to fly by Pluto and Charon in order to perform various remote-sensing scientific investigations and have a mission development cost less than $400M (FY92$) through launch plus 30 days. The long-life (6 - 10 years) mission duration and lightweight design make the Pluto spacecraft a good candidate for a number of other flyby missions to objects in the outer Solar System, and some of these were investigated by JPL in cooperation with NASA Code SL's (Solar System Exploration) Outer Planets Science Working Group (OPSWG) in 1993. The JPL team looked at what it would mean to fly one of these missions (if a third spacecraft were available) in terms of flight time, spacecraft modifications, and science payload resources; the OPSWG recommended science investigation modifications for the different targets based on the available resources. The missions could, in many cases, utilize less capable launch vehicles, thereby reducing life-cycle cost of the mission. Examples of the sort of targets which were investigated and looked attractive in terms of flight time are: Uranus, Neptune, Uranus/Neptune dual-mission, Trojan asteroids (624 Hektor, 617 Patroclus, others), 5145 Pholus (the reddest object known in the solar system), and Kuiper Belt objects (i.e., 1992 QB1) . This paper will present the results of this investigation in terms of potential science return, performance, and the potential for life-cycle cost reductions through inheritance from Pluto Fast Flyby .

Spacecraft System Failures and Anomalies Attributed to the Natural Space Environment

NASA Technical Reports Server (NTRS)

Bedingfield, Keith, L.; Leach, Richard D.; Alexander, Margaret B. (Editor)

1996-01-01

The natural space environment is characterized by many complex and subtle phenomena hostile to spacecraft. The effects of these phenomena impact spacecraft design, development, and operations. Space systems become increasingly susceptible to the space environment as use of composite materials and smaller, faster electronics increases. This trend makes an understanding of the natural space environment essential to accomplish overall mission objectives, especially in the current climate of better/cheaper/faster. This primer provides a brief overview of the natural space environment - definition, related programmatic issues, and effects on various spacecraft subsystems. The primary focus, however, is to catalog, through representative case histories, spacecraft failures and anomalies attributed to the natural space environment. This primer is one in a series of NASA Reference Publications currently being developed by the Electromagnetics and Aerospace Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center (MSFC), National Aeronautics and Space Administration (NASA).

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

NASA Technical Reports Server (NTRS)

Dakermanji, George; Lee, Leonine; Spitzer, Thomas

2016-01-01

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

Fast Plasma Investigation for MMS: Simulation of the Burst Triggering System

NASA Technical Reports Server (NTRS)

Barrie, A. C.; Dorelli, J. C.; Winkert, G. E.; Lobell, J. V.; Holland, M. P.; Adrian, M. L.; Pollock, C. J.

2011-01-01

The Magnetospheric Multiscale (MMS) mission will study small-scale reconnection structures and their rapid motions from closely spaced platforms using instruments capable of high angular, energy, and time resolution measurements. To meet these requirements, the Fast Plasma Instrument (FPI) consists of eight (8) identical half top-hat electron sensors and eight (8) identical ion sensors and an Instrument Data Processing Unit (IDPU). The sensors (electron or ion) are grouped into pairs whose 6 degree x 180 degree fields-of-view (FOV) are set 90 degrees apart. Each sensor is equipped with electrostatic aperture steering to allow the sensor to scan a 45 degree x 180 degree fan about the its nominal viewing (0 deflection) direction. Each pair of sensors, known as the Dual Electron Spectrometer (DES) and the Dual Ion Spectrometer (DIS), occupies a quadrant on the MMS spacecraft and the combination of the eight electron/ion sensors, employing aperture steering, image the full-sky every 30-ms (electrons) and 150-ms (ions), respectively. To probe the diffusion regions of reconnection, the highest temporal/spatial resolution mode of FPI results in the DES complement of a given spacecraft generating 6.5-Mb (raised dot) per second of electron data while the DIS generates 1.1-Mb (raised dot) per second of ion data yielding an FPI total data rate of 6.6-Mb (raised dot) per second. The FPI electron/ion data is collected by the IDPU then transmitted to the Central Data Instrument Processor (CIDP) on the spacecraft for science interest ranking. Only data sequences that contain the greatest amount of temporal/spatial structure will be intelligently down-linked by the spacecraft. This requires a data ranking process known as the burst trigger system. The burst trigger system uses pseudo physical quantities to approximate the local plasma environments. As each pseudo quantity will have a different value, a set of two scaling factors is employed for each pseudo term. These pseudo quantities are then combined at the instrument, spacecraft, and observatory level leading to a final ranking of data based on expected scientific interest. Here, we present simulations of the fixed point burst trigger system for the FPI. A variety of data sets based on previous mission data as well as analytical formulations are tested. Comparisons of floating point calculations versus the fixed point hardware simulation are shown. Analysis of the potential sources of error from overflows, quantization, etc. are examined and mitigation methods are presented. Finally a series of calibration curves are presented, showing the expected error in pseudo quantities based solely on the scale parameters chosen and the expected data range. We conclude with a presentation of the current base-lined FPI burst trigger approach.

Langmuir Probe Spacecraft Potential End Item Specification Document

NASA Technical Reports Server (NTRS)

Gilchrist, Brian; Curtis, Leslie (Technical Monitor)

2001-01-01

This document describes the Langmuir Probe Spacecraft Potential (LPSP) investigation of the plasma environment in the vicinity of the ProSEDS Delta II spacecraft. This investigation will employ a group of three (3) Langmuir Probe Assemblies, LPAs, mounted on the Delta II second stage to measure the electron density and temperature (n(sub e) and T(sub e)), the ion density (n(sub i)), and the spacecraft potential (V(sub s)) relative to the surrounding ionospheric plasma. This document is also intended to define the technical requirements and flight-vehicle installation interfaces for the design, development, assembly, testing, qualification, and operation of the LPSP subsystem for the Propulsive Small Expendable Deployer System (ProSEDS) and its associated Ground Support Equipment (GSE). This document also defines the interfaces between the LPSP instrument and the ProSEDS Delta II spacecraft, as well as the design, fabrication, operation, and other requirements established to meet the mission objectives. The LPSP is the primary measurement instrument designed to characterize the background plasma environment and is a supporting instrument for measuring spacecraft potential of the Delta II vehicle used for the ProSEDS mission. Specifically, the LPSP will use the three LPAs equally spaced around the Delta II body to make measurements of the ambient ionospheric plasma during passive operations to aid in validating existing models of electrodynamic-tether propulsion. These same probes will also be used to measure Delta II spacecraft potential when active operations occur. When the electron emitting plasma contractor is on, dense neutral plasma is emitted. Effective operation of the plasma contactor (PC) will mean a low potential difference between the Delta II second stage and the surrounding plasma and represents one of the voltage parameters needed to fully characterize the electrodynamic-tether closed circuit. Given that the LP already needs to be well away from any near-field disturbances around the Delta II, it is possible to use the same probe with a simple reconfiguration of the electronics to measure potential with respect to the ambient plasma. The LP measurement techniques are outlined in the following text and discussed in detail in the Appendix. The scientific goals of the investigation, the physical and electrical characteristics of the instrument, and the on-orbit measurement requirements are also discussed in this document.

The Lewis Research Center geomagnetic substorm simulation facility

NASA Technical Reports Server (NTRS)

Berkopec, F. D.; Stevens, N. J.; Sturman, J. C.

1977-01-01

A simulation facility was established to determine the response of typical spacecraft materials to the geomagnetic substorm environment and to evaluate instrumentation that will be used to monitor spacecraft system response to this environment. Space environment conditions simulated include the thermal-vacuum conditions of space, solar simulation, geomagnetic substorm electron fluxes and energies, and the low energy plasma environment. Measurements for spacecraft material tests include sample currents, sample surface potentials, and the cumulative number of discharges. Discharge transients are measured by means of current probes and oscilloscopes and are verified by a photomultiplier. Details of this facility and typical operating procedures are presented.

Deployable Propulsion, Power and Communications Systems for Solar System Exploration

NASA Technical Reports Server (NTRS)

Johnson, L.; Carr, J.; Boyd, D.

2017-01-01

NASA is developing thin-film based, deployable propulsion, power, and communication systems for small spacecraft that could provide a revolutionary new capability allowing small spacecraft exploration of the solar system. By leveraging recent advancements in thin films, photovoltaics, and miniaturized electronics, new mission-level capabilities will be enabled aboard lower-cost small spacecraft instead of their more expensive, traditional counterparts, enabling a new generation of frequent, inexpensive deep space missions. Specifically, thin-film technologies are allowing the development and use of solar sails for propulsion, small, lightweight photovoltaics for power, and omnidirectional antennas for communication.

Orbital science's 'Bermuda Triangle'

NASA Astrophysics Data System (ADS)

Sherrill, Thomas J.

1991-02-01

The effects of a part of the inner Van Allen belt lying closest to the earth, known as the South Atlantic Anomaly (SAA) upon spacecraft including the Hubble Space Telescope (HST), are discussed. The area consists of positively charged ions and electrons from the Van Allen Belt which become trapped in the earth's dipole field. Contor maps representing the number of protons per square centimeter per second having energies greater than 10 million electron volts are presented. It is noted that the HST orbit causes it to spend about 15 percent of its time in the SAA, but that, unlike the experience with earlier spacecraft, the satellite's skin, internal structure, and normal electronic's packaging provides sufficient protection against eletrons, although some higher energy protons still get through. Various charged particle effects which can arise within scientific instruments including fluorescence, Cerenkov radiation, and induced radioactivity are described.

Smart motor technology

NASA Technical Reports Server (NTRS)

Packard, D.; Schmitt, D.

1984-01-01

Current spacecraft design relies upon microprocessor control; however, motors usually require extensive additional electronic circuitry to interface with these microprocessor controls. An improved control technique that allows a smart brushless motor to connect directly to a microprocessor control system is described. An actuator with smart motors receives a spacecraft command directly and responds in a closed loop control mode. In fact, two or more smart motors can be controlled for synchronous operation.

Research on spacecraft electrical power conversion

NASA Technical Reports Server (NTRS)

Wilson, T. G.

1983-01-01

The history of spacecraft electrical power conversion in literature, research and practice is reviewed. It is noted that the design techniques, analyses and understanding which were developed make today's contribution to power computers and communication installations. New applications which require more power, improved dynamic response, greater reliability, and lower cost are outlined. The switching mode approach in electronic power conditioning is discussed. Technical aspects of the research are summarized.

CMOS Active Pixel Sensor Star Tracker with Regional Electronic Shutter

NASA Technical Reports Server (NTRS)

Yadid-Pecht, Orly; Pain, Bedabrata; Staller, Craig; Clark, Christopher; Fossum, Eric

1996-01-01

The guidance system in a spacecraft determines spacecraft attitude by matching an observed star field to a star catalog....An APS(active pixel sensor)-based system can reduce mass and power consumption and radiation effects compared to a CCD(charge-coupled device)-based system...This paper reports an APS (active pixel sensor) with locally variable times, achieved through individual pixel reset (IPR).

Vertical structure of the near-surface expanding ionosphere of comet 67P probed by Rosetta

NASA Astrophysics Data System (ADS)

Heritier, K. L.; Henri, P.; Vallières, X.; Galand, M.; Odelstad, E.; Eriksson, A. I.; Johansson, F. L.; Altwegg, K.; Behar, E.; Beth, A.; Broiles, T. W.; Burch, J. L.; Carr, C. M.; Cupido, E.; Nilsson, H.; Rubin, M.; Vigren, E.

2017-07-01

The plasma environment has been measured for the first time near the surface of a comet. This unique data set has been acquired at 67P/Churyumov-Gerasimenko during ESA/Rosetta spacecraft's final descent on 2016 September 30. The heliocentric distance was 3.8 au and the comet was weakly outgassing. Electron density was continuously measured with Rosetta Plasma Consortium (RPC)-Mutual Impedance Probe (MIP) and RPC-LAngmuir Probe (LAP) during the descent from a cometocentric distance of 20 km down to the surface. Data set from both instruments have been cross-calibrated for redundancy and accuracy. To analyse this data set, we have developed a model driven by Rosetta Orbiter Spectrometer for Ion and Neutral Analysis-COmetary Pressure Sensor total neutral density. The two ionization sources considered are solar extreme ultraviolet radiation and energetic electrons. The latter are estimated from the RPC-Ion and Electron Sensor (IES) and corrected for the spacecraft potential probed by RPC-LAP. We have compared the results of the model to the electron densities measured by RPC-MIP and RPC-LAP at the location of the spacecraft. We find good agreement between observed and modelled electron densities. The energetic electrons have access to the surface of the nucleus and contribute as the main ionization source. As predicted, the measurements exhibit a peak in the ionospheric density close to the surface. The location and magnitude of the peak are estimated analytically. The measured ionospheric densities cannot be explained with a constant outflow velocity model. The use of a neutral model with an expanding outflow is critical to explain the plasma observations.

Preliminary analysis of accelerated space flight ionizing radiation testing

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Stock, L. V.; Carter, D. J.; Chang, C. K.

1982-01-01

A preliminary analysis shows that radiation dose equivalent to 30 years in the geosynchronous environment can be accumulated in a typical composite material exposed to space for 2 years or less onboard a spacecraft orbiting from perigee of 300 km out to the peak of the inner electron belt (approximately 2750 km). Future work to determine spacecraft orbits better tailored to materials accelerated testing is indicated. It is predicted that a range of 10 to the 9th power to 10 to the 10th power rads would be accumulated in 3-6 mil thick epoxy/graphite exposed by a test spacecraft orbiting in the inner electron belt. This dose is equivalent to the accumulated dose that this material would be expected to have after 30 years in a geosynchronous orbit. It is anticipated that material specimens would be brought back to Earth after 2 years in the radiation environment so that space radiation effects on materials could be analyzed by laboratory methods.

South Atlantic anomaly and CubeSat design considerations

NASA Astrophysics Data System (ADS)

Fennelly, Judy A.; Johnston, William R.; Ober, Daniel M.; Wilson, Gordon R.; O'Brien, T. Paul; Huston, Stuart L.

2015-09-01

Effects of the South Atlantic Anomaly (SAA) on spacecraft in low Earth orbit (LEO) are well known and documented. The SAA exposes spacecraft in LEO to high dose of ionizing radiation as well as higher than normal rates of Single Event Upsets (SEU) and Single Event Latch-ups (SEL). CubeSats, spacecraft built around 10 x 10 x 10 cm cubes, are even more susceptible to SEUs and SELs due to the use of commercial off-the-shelf components for electronics and payload instrumentation. Examination of the SAA using both data from the Defense Meteorological Satellite Program (DMSP) and a new set of models for the flux of particles is presented. The models, AE9, AP9, and SPM for energetic electrons, energetic protons and space plasma, were developed for use in space system design. These models introduce databased statistical constraints on the uncertainties from measurements and climatological variability. Discussion of the models' capabilities and limitations with regard to LEO CubeSat design is presented.

Ballistic mode Mercury orbiter missions.

NASA Technical Reports Server (NTRS)

Hollenbeck, G. R.

1973-01-01

The MVM'73 Mercury flyby mission will initiate exploration of this unique planet. No firm plans for follow-on investigations have materialized due to the difficult performance requirements of the next logical step, an orbiter mission. Previous investigations of ballistic mode flight opportunities have indicated requirements for a Saturn V class launch vehicle. Consequently, most recent effort has been oriented to use of solar electric propulsion. More comprehensive study of the ballistic flight mode utilizing Venus gravity-assist has resulted in identification of timely high-performance mission opportunities compatible with programmed launch vehicles and conventional spacecraft propulsion technologies. A likely candidate for an initial orbiter mission is a 1980 opportunity which offers net orbiter spacecraft mass of about 435 kg with the Titan IIIE/Centaur launch vehicle and single stage solid propulsion for orbit insertion.

Multi-Functional Sandwich Composites for Spacecraft Applications: An Initial Assessment

NASA Technical Reports Server (NTRS)

Adams, Daniel O.; Webb, Nicholas Jason; Yarger, Cody B.; Hunter, Abigail; Oborn, Kelli D.

2007-01-01

Current spacecraft implement relatively uncoupled material and structural systems to address a variety of design requirements, including structural integrity, damage tolerance, radiation protection, debris shielding and thermal insulation. This investigation provided an initial assessment of multi-functional sandwich composites to integrate these diverse requirements. The need for radiation shielding was addressed through the selection of polymeric constituents with high hydrogen content. To provide increased damage tolerance and debris shielding, manufacturing techniques were developed to incorporate transverse stitching reinforcement, internal layers, and a self-healing ionomer membrane. To assess the effects of a space environment, thermal expansion behavior of the candidate foam materials was investigated under a vacuum and increasing temperature. Finally, a thermal expansion model was developed for foam under vacuum conditions and its predictive capability assessed.

Problems Encountered During the Recertification of the GLORY Solar Array Dual Axis Gimbal Drive Actuators

NASA Technical Reports Server (NTRS)

Saltzman, Marc; Schepis, Jospeh P.; Bruckner, Michael J.

2009-01-01

The Glory observatory is the current incarnation of the Vegetation Canopy Lidar (VCL) mission spacecraft bus. The VCL spacecraft bus, having been cancelled for programmatic reasons in 2000, was nearly integrated when it was put into storage for possible future use. The Glory mission was a suitable candidate for using this spacecraft and in 2006 an effort to recertify the two axis solar array gimbal drive after its extended storage was begun. What was expected to be a simple performance validation of the two dual axis gimbal stepper motors became a serious test, diagnosis and repair task once questions arose on the flight worthiness of the hardware. A significant test program logic flow was developed which identified decisions that could be made based on the results of individual recertification tests. Without disassembling the bi-axial gimbals, beginning with stepper motor threshold voltage measurements and relating these to powered drive torque measurements, both performed at the spacecraft integrator s facility, a confusing picture of the health of the actuators came to light. Tests at the gimbal assembly level and tests of the disassembled actuators were performed by the manufacturer to validate our results and torque discrepancies were noted. Further disassembly to the component level of the actuator revealed the source of the torque loss.

Dual Electron Spectrometer for Magnetospheric Multiscale Mission: Results of the Comprehensive Tests of the Engineering Test Unit

NASA Technical Reports Server (NTRS)

Avanov, Levon A.; Gliese, Ulrik; Mariano, Albert; Tucker, Corey; Barrie, Alexander; Chornay, Dennis J.; Pollock, Craig James; Kujawski, Joseph T.; Collinson, Glyn A.; Nguyen, Quang T.;

The 3HE in solar non-relativistic electron events

NASA Technical Reports Server (NTRS)

Reames, D. V.; Lin, R. P.

1985-01-01

The presence of 3He in 187 solar electron events observed on the ISEE-3 spacecraft during a 9-month period beginning in Aug. 1978 is reported. The 3He is present in over half of the events and in 2/3 of events with 19 keV electrons. It is suggested that 3He would be found in all electron events if these was a greater collection efficiency.

Low-energy particle experiments-electron analyzer (LEPe) onboard the Arase spacecraft

NASA Astrophysics Data System (ADS)

Kazama, Yoichi; Wang, Bo-Jhou; Wang, Shiang-Yu; Ho, Paul T. P.; Tam, Sunny W. Y.; Chang, Tzu-Fang; Chiang, Chih-Yu; Asamura, Kazushi

2017-12-01

In this report, we describe the low-energy electron instrument LEPe (low-energy particle experiments-electron analyzer) onboard the Arase (ERG) spacecraft. The instrument measures a three-dimensional distribution function of electrons with energies of ˜ 19 eV-19 keV. Electrons in this energy range dominate in the inner magnetosphere, and measurement of such electrons is important in terms of understanding the magnetospheric dynamics and wave-particle interaction. The instrument employs a toroidal tophat electrostatic energy analyzer with a passive 6-mm aluminum shield. To minimize background radiation effects, the analyzer has a background channel, which monitors counts produced by background radiation. Background counts are then subtracted from measured counts. Electronic components are radiation tolerant, and 5-mm-thick shielding of the electronics housing ensures that the total dose is less than 100 kRad for the one-year nominal mission lifetime. The first in-space measurement test was done on February 12, 2017, showing that the instrument functions well. On February 27, the first all-instrument run test was done, and the LEPe instrument measured an energy dispersion event probably related to a substorm injection occurring immediately before the instrument turn-on. These initial results indicate that the instrument works fine in space, and the measurement performance is good for science purposes.[Figure not available: see fulltext.

Integrating CCSDS Electronic Data Sheets into Flight Software

NASA Technical Reports Server (NTRS)

Wilmot, Jonathan

2017-01-01

This presentation will describe the new CCSDS Spacecraft Onboard Interfaces Services (SOIS) Electronic Data Sheet (EDS) standards and how they are being applied to data interfaces in software frameworks, tool chains, and ground systems across a range of missions at NASA and other agencies.

Comparison of Dawn and Dusk Precipitating Electron Energy Populations Shortly After the Initial Shock for the January 10th, 1997 Magnetic Cloud

NASA Technical Reports Server (NTRS)

Spann, J.; Germany, G.; Swift, W.; Parks, G.; Brittnacher, M.; Elsen, R.

1997-01-01

The observed precipitating electron energy between 0130 UT and 0400 UT of January 10 th, 1997, indicates that there is a more energetic precipitating electron population that appears in the auroral oval at 1800-2200 UT at 030) UT. This increase in energy occurs after the initial shock of the magnetic cloud reaches the Earth (0114 UT) and after faint but dynamic polar cap precipitation has been cleared out. The more energetic population is observed to remain rather constant in MLT through the onset of auroral activity (0330 UT) and to the end of the Polar spacecraft apogee pass. Data from the Ultraviolet Imager LBH long and LBH short images are used to quantify the average energy of the precipitating auroral electrons. The Wind spacecraft located about 100 RE upstream monitored the IMF and plasma parameters during the passing of the cloud. The affects of oblique angle viewing are included in the analysis. Suggestions as to the source of this hot electron population will be presented.

Charged Particle Periodicities in Saturn's Outer Magnetosphere

NASA Astrophysics Data System (ADS)

Carbary, J.; Mitchell, D.; Krimigis, S.; Krupp, N.

2006-12-01

The MIMI/LEMMS instrument on the Cassini spacecraft has measured energetic electrons in the energy range 20-300 keV within Saturn's magnetosphere. In the outer magnetosphere beyond about 20 RS, these electrons and their spectral index display strong variations with periods comparable to the 10.76 hour period measured by radio observations of Cassini. Inside about 20 RS, such electron variations may be present but are masked by satellite and ring effects. Electron periodicities are most easily recognized on the "night side" segments of the Cassini orbits, although they are also observed to some extent on the day side. For both day and night sides, a wavelet analysis of de-trended count rates in the 20-40 RS region reveals a mean period of 10.52 +/- 0.74 hrs for the six electron channels investigated. If constrained to the night side only, a wavelet analysis gives a mean period of 10.88 +/- 0.52 hours. These periods were obtained from several orbits of the Cassini spacecraft during the two-year period from SOI (July 2004) to the present (November 2006).

Pre- and posttreatment techniques for spacecraft water recovery

NASA Technical Reports Server (NTRS)

Putnam, David F.; Colombo, Gerald V.; Michalek, William F.

1987-01-01

The objective was to develop techniques for satisfactory pretreatment of waste water (urine and wash water) prior to recovery by distillation and satisfactory post-treatment of the recovered water and humidity condensate for purification to the high quality necessary for reuse. The effort included literature and laboratory investigations, feasibility evaluations of candidate approaches, and development of conceptual designs for a waste water pretreatment system and a recovered water post-treatment system.

A low-mass faraday cup experiment for the solar wind

NASA Technical Reports Server (NTRS)

Lazarus, A. J.; Steinberg, J. T.; Mcnutt, R. L., Jr.

1993-01-01

Faraday cups have proven to be very reliable and accurate instruments capable of making 3-D velocity distribution measurements on spinning or 3-axis stabilized spacecraft. Faraday cup instrumentation continues to be appropriate for heliospheric missions. As an example, the reductions in mass possible relative to the solar wind detection system about to be flown on the WIND spacecraft were estimated. Through the use of technology developed or used at the MIT Center for Space Research but were not able to utilize for WIND: surface-mount packaging, field-programmable gate arrays, an optically-switched high voltage supply, and an integrated-circuit power converter, it was estimated that the mass of the Faraday Cup system could be reduced from 5 kg to 1.8 kg. Further redesign of the electronics incorporating hybrid integrated circuits as well as a decrease in the sensor size, with a corresponding increase in measurement cycle time, could lead to a significantly lower mass for other mission applications. Reduction in mass of the entire spacecraft-experiment system is critically dependent on early and continual collaborative efforts between the spacecraft engineers and the experimenters. Those efforts concern a range of issues from spacecraft structure to data systems to the spacecraft power voltage levels. Requirements for flight qualification affect use of newer, lighter electronics packaging and its implementation; the issue of quality assurance needs to be specifically addressed. Lower cost and reduced mass can best be achieved through the efforts of a relatively small group dedicated to the success of the mission. Such a group needs a fixed budget and greater control over quality assurance requirements, together with a reasonable oversight mechanism.

Selection and Prioritization of Advanced Propulsion Technologies for Future Space Missions

NASA Technical Reports Server (NTRS)

Eberle, Bill; Farris, Bob; Johnson, Les; Jones, Jonathan; Kos, Larry; Woodcock, Gordon; Brady, Hugh J. (Technical Monitor)

2002-01-01

The exploration of our solar system will require spacecraft with much greater capability than spacecraft which have been launched in the past. This is particularly true for exploration of the outer planets. Outer planet exploration requires shorter trip times, increased payload mass, and ability to orbit or land on outer planets. Increased capability requires better propulsion systems, including increased specific impulse. Chemical propulsion systems are not capable of delivering the performance required for exploration of the solar system. Future propulsion systems will be applied to a wide variety of missions with a diverse set of mission requirements. Many candidate propulsion technologies have been proposed but NASA resources do not permit development of a] of them. Therefore, we need to rationally select a few propulsion technologies for advancement, for application to future space missions. An effort was initiated to select and prioritize candidate propulsion technologies for development investment. The results of the study identified Aerocapture, 5 - 10 KW Solar Electric Ion, and Nuclear Electric Propulsion as high priority technologies. Solar Sails, 100 Kw Solar Electric Hall Thrusters, Electric Propulsion, and Advanced Chemical were identified as medium priority technologies. Plasma sails, momentum exchange tethers, and low density solar sails were identified as high risk/high payoff technologies.

Feasibility of Juno radio occultations of the Io plasma torus

NASA Astrophysics Data System (ADS)

Phipps, P. H.; Withers, P.

2016-12-01

Jupiter's magnetosphere is driven by internally produced plasma. The innermost Galilean satellite, Io, isthe dominant source of this plasma. Volcanoes on Io's surface create an atmosphere of sulfur and oxygenwhich escapes into Jupiter's magnetosphere and becomes ionized. This ionized material is trapped byJupiter's magnetic field and creates a torus of plasma centered at Io's orbital radius, called the Io plasmatorus. This torus is divided into three regions distinct in both density and composition. Densities in thistorus can be probed by spacecraft via radio occultations. A radio occultation occurs when plasma comesbetween a spacecraft and a receiver during a time when the spacecraft is sending a radio signal. The Junospacecraft, which arrived in orbit around Jupiter in July 2016, is in an orbit which will be ideal forperforming radio occultations of the Io plasma torus. We test the feasibility of using thetelecommunications system on the Juno spacecraft to perform a radio occultation. Io plasma torusdensities derived from Voyager 1 data are used in creating a model torus. Using the Ka and X-band radiofrequencies we derive vertical profiles for the total electron content of the modeled Io plasma torus. AMarkov Chain Monte Carlo fit is performed on the derived profiles to extract, for each of the torusregions, the scale height and peak total electron content. The scale height can be used to derive atemperature for the torus while the peak total electron content can be used to derive the peak electrondensity. We show that Juno radio occultation measurements of the Io plasma torus are feasible andscientifically valuable.

Multispacecraft observations of the electron current sheet, neighboring magnetic islands, and electron acceleration during magnetotail reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Lijen; Bessho, Naoki; Bhattacharjee, Amitava

Open questions concerning structures and dynamics of diffusion regions and electron acceleration in collisionless magnetic reconnection are addressed based on data from the four-spacecraft mission Cluster and particle-in-cell simulations. Using time series of electron distribution functions measured by the four spacecraft, distinct electron regions around a reconnection layer are mapped out to set the framework for studying diffusion regions. A spatially extended electron current sheet (ecs), a series of magnetic islands, and bursts of energetic electrons within islands are identified during magnetotail reconnection with no appreciable guide field. The ecs is collocated with a layer of electron-scale electric fields normalmore » to the ecs and pointing toward the ecs center plane. Both the observed electron and ion densities vary by more than a factor of 2 within one ion skin depth north and south of the ecs, and from the ecs into magnetic islands. Within each of the identified islands, there is a burst of suprathermal electrons whose fluxes peak at density compression sites [L.-J. Chen et al., Nat. Phys. 4, 19 (2008)] and whose energy spectra exhibit power laws with indices ranging from 6 to 7.3. These results indicate that the in-plane electric field normal to the ecs can be of the electron scale at certain phases of reconnection, electrons and ions are highly compressible within the ion diffusion region, and for reconnection involving magnetic islands, primary electron acceleration occurs within the islands.« less

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.

Independence and Interdependence: An Analysis of Pre-Service Candidates' Use of Focused Assignments on an Electronic Discussion Forum during the Initial Field Experience

ERIC Educational Resources Information Center

Fisch, Audrey A.; Bennett, Deborah J.

2011-01-01

This article describes a case study using an electronic learning platform for creating an interactive learning community through asynchronous discussion to enhance the initial field experience of secondary math and English teacher candidates enrolled in Field Experience. We identified three problems with the field experience course--lack of…

Laboratory Experiments Enabling Electron Beam use in Tenuous Space Plasmas

NASA Astrophysics Data System (ADS)

Miars, G.; Leon, O.; Gilchrist, B. E.; Delzanno, G. L.; Castello, F. L.; Borovsky, J.

2017-12-01

A mission concept is under development which involves firing a spacecraft-mounted electron beam from Earth's magnetosphere to connect distant magnetic field lines in real time. To prevent excessive spacecraft charging and consequent beam return, the spacecraft must be neutralized in the tenuous plasma environment of the magnetosphere. Particle-In-Cell (PIC) simulations suggest neutralization can be accomplished by emitting a neutral plasma with the electron beam. Interpretation of these simulations also led to an ion emission model in which ion current is emitted from a quasi-neutral plasma as defined by the space charge limit [1,2]. Experiments were performed at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL) to help validate the ion emission model. A hollow cathode plasma contactor was used as a representative spacecraft and charged with respect to the chamber walls to examine the effect of spacecraft charging on ion emission. Retarding Potential Analyzer (RPA) measurements were performed to understand ion flow velocity as this parameter relates directly to the expected space charge limit. Planar probe measurements were also made to identify where ion emission primarily occurred and to determine emission current density levels. Evidence of collisions within the plasma (particularly charge exchange collisions) and a simple model predicting emitted ion velocities are presented. While a detailed validation of the ion emission model and of the simulation tools used in [1,2] is ongoing, these measurements add to the physical understanding of ion emission as it may occur in the magnetosphere. 1. G.L. Delzanno, J.E. Borovsky, M.F. Thomsen, J.D. Moulton, and E.A. MacDonald, J. Geophys. Res. Space Physics 120, 3647, 2015. 2. G.L. Delzanno, J.E. Borovsky, M.F. Thomsen, and J.D. Moulton, J. Geophys. Res. Space Physics 120, 3588, 2015. ________________________________ * This work is supported by Los Alamos National Laboratory.

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

NASA Technical Reports Server (NTRS)

Meyer, Marit E.

2015-01-01

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

26-day Periodicities in Low-Energy Electrons at Saturn

NASA Astrophysics Data System (ADS)

Carbary, J. F.

2016-12-01

A Lomb periodogram analysis has been carried out on the electron fluxes measured by the Electron Spectrometer (ELS) of the Cassini Plasma Science (CAPS) instrument. All available ELS data from 2004 to mid-2011 were used in the analysis. The observations were filtered so they were between 15 RS (1 RS = 60268 km) and the magnetopause, and farther than 0.5 RS from Titan. Within a 0.1 d to 50 d periodicity window, the strongest periodicities in the periodograms were at 26 d for electrons from 20 eV to 1000 eV, while for electrons at higher energies strong periodicities between 18 d and 20 d are associated with the trajectory of the spacecraft itself. Surprisingly, the amplitude of the 26 d period was a factor of 100 greater than the better known 10.7 h period associated with planetary rotation. The strongest periodicities were not field-aligned, but were between pitch angles of 30° and 150°. Results will be compared to those from energetic electrons (E > 27 keV). A signal near Titan's orbital period (15.9 d) is probably caused by the spacecraft trajectory, and a 2D flux model is used to demonstrate this.

Voyager 2 Uranus targeting strategy

NASA Technical Reports Server (NTRS)

Cesarone, R. J.; Gray, D. L.; Potts, C. L.; Francis, K.

1986-01-01

One of the major challenges involved in the Voyager 2 Uranus flyby is to deliver the spacecraft to an appropriate aimpoint at the optimum time, so as to maximize the science return of the mission, while yet keeping propellant expenditure low. An unusual targeting strategy has been devised to satisfy these requirements. Its complexity arises from the great distance of the planet Uranus and the limited performance capabilities of Voyager. This selected strategy is developed in relation to a set of candidate strategies, mission requirements and shifting science objectives. The analysis of these candidates is conducted via a Monte Carlo simulation, the results of which yield data for the comparative evaluation and eventual and selection of the actual targeting strategy to be employed.

Spacecraft Charging Technology Conference (9th) Held in Tsukuba, Japan on 4-8 April 2005. Book of Abstracts

DTIC Science & Technology

2005-04-01

Electron Emission for Modeling Spacecraft Charging(025ole) Adrian Wheelock - AFRL/VSBX Simulations of Current Coupling in Ion Beam...Boxue Du - Tianjin University Discharge Characteristic of Gamma-Ray Irradiated Polybutylene Naphthalatem3-*u) Shana Figueroa - Air Force Research...FAX : (858)826-1653 E-mail : myron.j.mandell @saic.com David L. Cooke, Adrian Wheelock Air Force Research Laboratory, Space Vehicles

An intelligent robot for helping astronauts

NASA Technical Reports Server (NTRS)

Erickson, J. D.; Grimm, K. A.; Pendleton, T. W.

1994-01-01

This paper describes the development status of a prototype supervised intelligent robot for space application for purposes of (1) helping the crew of a spacecraft such as the Space Station with various tasks, such as holding objects and retrieving/replacing tools and other objects from/into storage, and (2) for purposes of retrieving detached objects, such as equipment or crew, that have become separated from their spacecraft. In addition to this set of tasks in this low-Earth-orbiting spacecraft environment, it is argued that certain aspects of the technology can be viewed as generic in approach, thereby offering insight into intelligent robots for other tasks and environments. Candidate software architectures and their key technical issues which enable real work in real environments to be accomplished safely and robustly are addressed. Results of computer simulations of grasping floating objects are presented. Also described are characterization results on the usable reduced gravity environment in an aircraft flying parabola (to simulate weightlessness) and results on hardware performance there. These results show it is feasible to use that environment for evaluative testing of dexterous grasping based on real-time vision of freely rotating and translating objects.

Spacecraft fire-safety experiments for space station: Technology development mission

NASA Technical Reports Server (NTRS)

Youngblood, Wallace W.

1988-01-01

Three concept designs for low-gravity, fire-safety related experiments are presented, as selected for the purpose of addressing key issues of enhancing safety and yet encouraging access to long-duration, manned spacecraft such as the NASA space station. The selected low-gravity experiments are the following: (1) an investigation of the flame-spread rate and combustion-product evolution of the burning of typical thicknesses of spacecraft materials in very low-speed flows; (2) an evaluation of the interaction of fires and candidate extinguishers in various fire scenarios; and (3) an investigation of the persistence and propagation of smoldering and deep-seated combustion. Each experiment is expected to provide fundamental combustion-science data, as well as the fire-safety applications, and each requires the unique long-duration, low-gravity environment of the space station. Two generic test facilities, i.e., the Combustion Tunnel Facility and the Combustion Facility, are proposed for space station accommodation to support the selected experiments. In addition, three near-term, fire-safety related experiments are described along with other related precursor activities.

Constraining the Origin of Impact Craters on Al Foils from the Stardust Interstellar Dust Collector

NASA Technical Reports Server (NTRS)

Stroud, Rhonda M.; Achilles, Cheri; Allen, Carlton; Ansari, Asna; Bajt, Sasa; Bassim, Nabil; Bastien, Ron S.; Bechtel, H. A.; Borg, Janet; Brenker, Frank E.;

76 FR 65742 - Notice of Proposed Information Collection for Public Comment; Inspector Candidate Assessment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-24

... Information Collection for Public Comment; Inspector Candidate Assessment Questionnaire AGENCY: Office of the... following information: Title of Proposal: Inspector Candidate Assessment Questionnaire. OMB Control Number... trained and certified by HUD are requested to electronically submit the questionnaire via the Internet...

Preentry communications study. Outer planets atmospheric entry probe

NASA Technical Reports Server (NTRS)

Hinrichs, C. A.

1976-01-01

A pre-entry communications study is presented for a relay link between a Jupiter entry probe and a spacecraft in hyperbolic orbit. Two generic communications links of interest are described: a pre-entry link to a spun spacecraft antenna, and a pre-entry link to a despun spacecraft antenna. The propagation environment of Jupiter is defined. Although this is one of the least well known features of Jupiter, enough information exists to reasonably establish bounds on the performance of a communications link. Within these bounds, optimal carrier frequencies are defined. The next step is to identify optimal relative geometries between the probe and the spacecraft. Optimal trajectories are established for both spun and despun spacecraft antennas. Given the optimal carrier frequencies, and the optimal trajectories, the data carrying capacities of the pre-entry links are defined. The impact of incorporating pre-entry communications into a basic post entry probe is then assessed. This assessment covers the disciplines of thermal control, power source, mass properties and design layout. A conceptual design is developed of an electronically despun antenna for use on a Pioneer class of spacecraft.

NASA's Space Environments and Effects Program: Technology for the New Millennium

NASA Technical Reports Server (NTRS)

Hardage, Donna M.; Pearson, Steven D.

2000-01-01

Current trends in spacecraft development include the use of advanced technologies while maintaining the "faster, better, cheaper" philosophy. Spacecraft designers are continually designing with smaller and faster electronics as well as lighter and thinner materials providing better performance, lower weight, and ultimately lower costs. Given this technology trend, spacecraft will become increasingly susceptible to the harsh space environments, causing damaging or even disabling effects on space systems. NASA's Space Environments and Effects (SEE) Program defines the space environments and provides advanced technology development to support the design, development, and operation of spacecraft systems that will accommodate or mitigate effects due to the harsh space environments. This Program provides a comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this multitudinous information is properly maintained and inserted into spacecraft design programs. A description of the SEE Program, its accomplishments, and future activities is provided.

Materials for Spacecraft. Chapter 6

NASA Technical Reports Server (NTRS)

Finckenor, Miria M.

2016-01-01

The general knowledge in this chapter is intended for a broad variety of spacecraft: manned or unmanned, low Earth to geosynchronous orbit, cis-lunar, lunar, planetary, or deep space exploration. Materials for launch vehicles are covered in chapter 7. Materials used in the fabrication of spacecraft hardware should be selected by considering the operational requirements for the particular application and the design engineering properties of the candidate materials. The information provided in this chapter is not intended to replace an in-depth materials study but rather to make the spacecraft designer aware of the challenges for various types of materials and some lessons learned from more than 50 years of spaceflight. This chapter discusses the damaging effects of the space environment on various materials and what has been successfully used in the past or what may be used for a more robust design. The material categories covered are structural, thermal control for on-orbit and re-entry, shielding against radiation and meteoroid/space debris impact, optics, solar arrays, lubricants, seals, and adhesives. Spacecraft components not directly exposed to space must still meet certain requirements, particularly for manned spacecraft where toxicity and flammability are concerns. Requirements such as fracture control and contamination control are examined, with additional suggestions for manufacturability. It is important to remember that the actual hardware must be tested to understand the real, "as-built" performance, as it could vary from the design intent. Early material trades can overestimate benefits and underestimate costs. An example of this was using graphite/epoxy composite in the International Space Station science racks to save weight. By the time the requirements for vibration isolation, Space Shuttle frequencies, and experiment operations were included, the weight savings had evaporated.

Measurements of the spatial structure and directivity of 100 KeV photon sources in solar flares using PVO and ISEE-3 spacecraft

NASA Technical Reports Server (NTRS)

Anderson, Kinsey A.

1991-01-01

The objective of this grant was to measure the spatial structure and directivity of the hard X-ray and low energy gamma-ray (100 keV-2 MeV) continuum sources in solar flares using stereoscopic observations made with spectrometers aboard the Pioneer Venus Orbiter (PVO) and Third International Sun Earth Explorer (ISEE-3) spacecraft. Since the hard X-ray emission is produced by energetic electrons through the bremsstrahlung process, the observed directivity can be directly related to the 'beaming' of electrons accelerated during the flare as they propagate from the acceleration region in the corona to the chromosphere/transition region. Some models (e.g., the thick-target model) predict that most of the impulsive hard X-ray/low energy gamma-ray source is located in the chromosphere, the effective height of the X-ray source above the photosphere increasing with the decrease in the photon energy. This can be verified by determining the height-dependence of the photon source through stereoscopic observations of those flares which are partially occulted from the view of one of the two spacecraft. Thus predictions about beaming of electrons as well as their spatial distributions could be tested through the analysis proposed under this grant.

New DMSP database of precipitating auroral electrons and ions

NASA Astrophysics Data System (ADS)

Redmon, Robert J.; Denig, William F.; Kilcommons, Liam M.; Knipp, Delores J.

2017-08-01

Since the mid-1970s, the Defense Meteorological Satellite Program (DMSP) spacecraft have operated instruments for monitoring the space environment from low Earth orbit. As the program evolved, so have the measurement capabilities such that modern DMSP spacecraft include a comprehensive suite of instruments providing estimates of precipitating electron and ion fluxes, cold/bulk plasma composition and moments, the geomagnetic field, and optical emissions in the far and extreme ultraviolet. We describe the creation of a new public database of precipitating electrons and ions from the Special Sensor J (SSJ) instrument, complete with original counts, calibrated differential fluxes adjusted for penetrating radiation, estimates of the total kinetic energy flux and characteristic energy, uncertainty estimates, and accurate ephemerides. These are provided in a common and self-describing format that covers 30+ years of DMSP spacecraft from F06 (launched in 1982) to F18 (launched in 2009). This new database is accessible at the National Centers for Environmental Information and the Coordinated Data Analysis Web. We describe how the new database is being applied to high-latitude studies of the colocation of kinetic and electromagnetic energy inputs, ionospheric conductivity variability, field-aligned currents, and auroral boundary identification. We anticipate that this new database will support a broad range of space science endeavors from single observatory studies to coordinated system science investigations.

Variations in the magnetopause current layer

NASA Astrophysics Data System (ADS)

Laakso, H. E.; Middleton, H. R.

2017-12-01

We use multi-point observations from the Cluster spacecraft to investigate the variations in the magnetopause current layer. With help of the curlometer technique one can determine the magnetopause current and its variability. Most of the time the magnetopause location is moving back and forth, so during any given pass the current layer is crossed several times. We use such crossings to investigate the characteristics of the current layer as the solar wind pressure varies (and the magnetopause moves accordingly). In addition we take an advantage of the ambient electron measurements from the EDI experiment which have been calibrated against the PEACE electron spectrometer data. These data can be used to detect fast variations of 1 keV electrons at resolution of 1-100 ms. Overall, Cluster observations are highly complimentary to the MMS observations due to the polar orbit of the Cluster spacecraft which provide fast vertical profiles of the magnetopause current layer.

Optical radiation from the interaction of energetic atoms, ions, electrons, and photons with surfaces

NASA Technical Reports Server (NTRS)

Tolk, N. H.; Albridge, R. G.; Haglund, R. F., Jr.; Mendenhall, M. H.

1985-01-01

Heavy particle, electron, and UV photon bombardment of solid surfaces has been recently observed to result in the emission of infrared, visible, and ultraviolet radiation. This effect occurs over a wide range of incident projectile energies. Line radiation arising from transitions between discrete atomic or molecular levels may be attributed to the decay of excited particles which have been sputtered or electronically/chemically desorbed from the surface. Broadband continuum radiation, which is also observed, is believed to arise either from fluorescence of the near surface bulk or from the radiative decay of desorbed excited clusters. Spacecraft, in the ambient near Earth environment, are subject to such bombardment. The dynamics of energetic particle and photon beam interactions with surfaces which lead to surface erosion and glow phenomena will be treated. In addition, projected experimental and theoretical studies of oxygen and nitrogen beam surface interactions on materials characteristic of spacecraft surfaces will be discussed.

Electron heating and the potential jump across fast mode shocks. [in interplanetary space

NASA Technical Reports Server (NTRS)

Schwartz, Steven J.; Thomsen, Michelle F.; Bame, S. J.; Stansberry, John

1988-01-01

Two different methods were applied to determine the cross-shock potential jump in the de Hoffmann-Teller reference frame, using a data set that represented 66 crossings of the terrestrial bow shock and 14 interplanetary shocks observed by various ISEE spacecraft, and one crossing each of the Jovian bow shock and the Uranian bow shock made by the Voyager spacecraft. Results for estimates of the electrostatic potential based on an estimate of the jump in electron enthalpy correlated well with estimates based on Liouville's theorem, although the Liouville-determined values were systematically the higher of the two, suggesting that significant irreversible processes contribute to the shape of the downstream distribution. The potential jump corresponds to approximately 12-15 percent of the incident ion ram kinetic energy, and was found not to be controlled by the Mach number, plasma beta, shock geometry, or electron to ion temperature ratios.

A systems approach to solder joint fatigue in spacecraft electronic packaging

NASA Technical Reports Server (NTRS)

Ross, R. G., Jr.

1991-01-01

Differential expansion induced fatigue resulting from temperature cycling is a leading cause of solder joint failures in spacecraft. Achieving high reliability flight hardware requires that each element of the fatigue issue be addressed carefully. This includes defining the complete thermal-cycle environment to be experienced by the hardware, developing electronic packaging concepts that are consistent with the defined environments, and validating the completed designs with a thorough qualification and acceptance test program. This paper describes a useful systems approach to solder fatigue based principally on the fundamental log-strain versus log-cycles-to-failure behavior of fatigue. This fundamental behavior has been useful to integrate diverse ground test and flight operational thermal-cycle environments into a unified electronics design approach. Each element of the approach reflects both the mechanism physics that control solder fatigue, as well as the practical realities of the hardware build, test, delivery, and application cycle.

The Giotto electron plasma experiment

NASA Technical Reports Server (NTRS)

Reme, H.; Cotin, F.; Cros, A.; Medale, J. L.; Sauvaud, J. A.

1987-01-01

The RPA-Copernic experiment aboard Giotto is described. The experiment is designed to measure the three-dimensional distributions of electrons between 10 eV and 30 keV (by the RPA-1 EESA spectrometer) and the composition and distribution, close to the comet, of thermal positive ions in the mass range 10-213 amu (by the RPA-2 PICCA electrostatic mass analyzer). Three microprocessors interface RPA-1 EESA with RPA-2 PICCA and with the spacecraft and perform extensive onboard data processing. The experiment was operated successfully aboard the spacecraft in September 1985 during the encounter of Giotto with the comet Halley. The results provided by the EESA-1 indicate that the solar wind interaction with the comet Halley forms a well-defined bow shock with features quite different from the features of the comet Giacobini-Zinner bow shock; the data also showed a presence of accelerated keV electrons at the cometary bow shock, upstream and in the transition region.

MARS GLOBAL SURVEYOR LIGHTING TEST

NASA Technical Reports Server (NTRS)

1996-01-01

In KSC's Payload Hazardous Servicing Facility (PHSF), Jet Propulsion Laboratory (JPL) workers are conducting a solar illumination test of the solar panels on the Mars Global Surveyor. The Surveyor is outfitted with two solar arrays, each featuring two panels, that provide electrical power for operating the spacecraft's electronic equipment and scientific instruments, as well as charging two nickel hydrogen batteries that provide power when the spacecraft is in the dark. For launch, the solar arrays will be folded against the side of the spacecraft. The Mars Global Surveyor is being prepared for launch aboard a Delta II expendable launch vehicle during a launch window opening Nov. 6.

Anomalously high potentials observed on ISEE

NASA Technical Reports Server (NTRS)

Whipple, E. C.; Krinsky, I. S.; Torbert, R. B.; Olsen, R. C.

1985-01-01

Data from two electric field experiments and from the plasma composition experiment on ISEE-1 are used to show that the spacecraft charged to close to -70 V in sunlight at 0700 UT on March 17, 1978. Data from the electron spectrometer experiment show that there was a potential barrier of -10 to -20 V about the spacecraft during this event. The potential barrier was effective in turning back emitted photoelectrons to the spacecraft. The stringent electrostatic cleanliness specifications imposed on ISEE make the presence of differential charging unlikely. Modeling of this event is required to determine if the barrier was produced by the presence of space charge.

Three axis pulsed plasma thruster with angled cathode and anode strip lines

NASA Technical Reports Server (NTRS)

Cassady, R. Joseph (Inventor); Myers, Roger M. (Inventor); Osborne, Robert D. (Inventor)

2001-01-01

A spacecraft attitude and altitude control system utilizes sets of three pulsed plasma thrusters connected to a single controller. The single controller controls the operation of each thruster in the set. The control of a set of three thrusters in the set makes it possible to provide a component of thrust along any one of three desired axes. This configuration reduces the total weight of a spacecraft since only one controller and its associated electronics is required for each set of thrusters rather than a controller for each thruster. The thrusters are positioned about the spacecraft such that the effect of the thrusters is balanced.

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.

What's the Kepler Spacecraft Been Up To?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-03-01

Remember back in May 2013 when the second of Keplers reaction wheels failed, rendering it unable to control its precision pointing? As a result of a clever backup plan by intrepid scientists, Kepler is still going strong! This January, a paper was published describing some of the results from the first year of the extended Kepler mission, known as K2.K2: A Second ChanceHistograms of the K2 planet candidate sample (solid yellow) compared with planet candidates from the first four months of Kepler observations (blue diagonal lines). The histograms compare planet radius, orbital period, and brightness. [Vanderburg et al. 2016]After an incredibly successful five years discovering transiting exoplanets, the failure of two of Keplers reaction wheels (which allow it to maintain its orientation) looked like it would shut down the mission. Luckily, the scientific community came up with the ingenious plan of stabilizing the telescope using the radiation pressure exerted by the Sun. Though this solution limits Kepler to observing within the ecliptic plane, it has provided a new life lease for the project.Despite the significantly worsened pointing precision in the K2 mission, new analysis techniques have been developed that decouple the motion of the spacecraft from its observations, resulting in an observational precision for K2 thats within 35% of the original precision achieved by Kepler.Using these techniques, a team of scientists led by Andrew Vanderburg (HarvardSmithsonian Center for Astrophysics) analyzed the publicly released data from the first year of the K2 mission. In a new study, they describe the results from the 59,174 targets that Kepler has observed in that time.Planetary CandidatesVanderburg and collaborators report that K2 has detected 234 planetary candidates around 208 stars in its first year. These candidates span a range of sizes from gas-giant to smaller than the Earth, and have orbital periods that range from hours to more than a month. The list includes:26 candidates with sizes between 1 and 4 Earth radii, orbiting bright stars. These are well suited for precise radial velocity follow-up.10 candidates with radii between 1.6 and 4 Earth radii that are likely to have gaseous envelopes. These are well suited for atmospheric characterization.8 sub-Earth sized candidates, the smallest of which are about 0.75 times the size of Earth.Vanderburg and collaborators make all of their data products (light curves, spectra, vetting diagnostics, etc.) publicly available. Their observations and data provide an excellent starting point for follow-up on the many potential planets discovered by K2 within the first year of its proposed three-year mission. And given this already long list of candidates, its clear that while Keplers power may have been reined in slightly, this telescope still has many more discoveries to show us.CitationAndrew Vanderburg et al 2016 ApJS 222 14. doi:10.3847/0067-0049/222/1/14

Temporal Characteristics of Electron Flux Events at Geosynchronous Orbit

NASA Astrophysics Data System (ADS)

Olson, D. K.; Larsen, B.; Henderson, M. G.

2017-12-01

Geosynchronous satellites such as the LANL-GEO fleet are exposed to hazardous conditions when they encounter regions of hot, intense plasma such as that from the plasma sheet. These conditions can lead to the build-up of charge on the surface of a spacecraft, with undesired, and often dangerous, side effects. Observation of electron flux levels at geosynchronous orbit (GEO) with multiple satellites provides a unique view of plasma sheet access to that region. Flux "events", or periods when fluxes are elevated continuously above the LANL-GEO spacecraft charging threshold, can be characterized by duration in two dimensions: a spatial dimension of local time, describing the duration of an event from the perspective of a single spacecraft, and a temporal dimension describing the duration in time in which high energy plasma sheet particles have access to geosynchronous orbit. We examine the statistical properties of the temporal duration of 8 keV electron flux events at geosynchronous orbit over a twelve-year period. These results, coupled with the spatial duration characteristics, provide the key information needed to formulate a statistical model for forecasting the electron flux conditions at GEO that are correlated with LANL-GEO surface charging. Forecasting models are an essential component to understanding space weather and mitigating the dangers of surface charging on our satellites. We also examine the correlation of flux event durations with solar wind parameters and geomagnetic indices, identifying the data needed to improve upon a statistical forecasting model

JPL control/structure interaction test bed real-time control computer architecture

NASA Technical Reports Server (NTRS)

Briggs, Hugh C.

1989-01-01

The Control/Structure Interaction Program is a technology development program for spacecraft that exhibit interactions between the control system and structural dynamics. The program objectives include development and verification of new design concepts - such as active structure - and new tools - such as combined structure and control optimization algorithm - and their verification in ground and possibly flight test. A focus mission spacecraft was designed based upon a space interferometer and is the basis for design of the ground test article. The ground test bed objectives include verification of the spacecraft design concepts, the active structure elements and certain design tools such as the new combined structures and controls optimization tool. In anticipation of CSI technology flight experiments, the test bed control electronics must emulate the computation capacity and control architectures of space qualifiable systems as well as the command and control networks that will be used to connect investigators with the flight experiment hardware. The Test Bed facility electronics were functionally partitioned into three units: a laboratory data acquisition system for structural parameter identification and performance verification; an experiment supervisory computer to oversee the experiment, monitor the environmental parameters and perform data logging; and a multilevel real-time control computing system. The design of the Test Bed electronics is presented along with hardware and software component descriptions. The system should break new ground in experimental control electronics and is of interest to anyone working in the verification of control concepts for large structures.

Plasma Waves Observed in the Cusp Turbulent Boundary Layer: An Analysis of High Time Resolution Wave and Particle Measurements from the Polar Spacecraft

NASA Technical Reports Server (NTRS)

Pickett, J. S.; Franz, J. R.; Scudder, J. D.; Menietti, J. D.; Gurnett, D. A.; Hospodarsky, G. B.; Braunger, R. M.; Kintner, P. M.; Kurth, W. S.

2001-01-01

The boundary layer located in the cusp and adjacent to the magnetopause is a region that is quite turbulent and abundant with waves. The Polar spacecraft's orbit and sophisticated instrumentation are ideal for studying this region of space. Our analysis of the waveform data obtained in this turbulent boundary layer shows broadband magnetic noise extending up to a few kilohertz (but less than the electron cyclotron frequency); sinusoidal bursts (a few tenths of a second) of whistler mode waves at around a few tens of hertz, a few hundreds of hertz, and just below the electron cyclotron frequency; and bipolar pulses, interpreted as electron phase-space holes. In addition, bursts of electron cyclotron harmonic waves are occasionally observed with magnetic components. We show evidence of broadband electrostatic bursts covering a range of approx. 3 to approx. 25 kHz (near but less than the plasma frequency) occurring in packets modulated at the frequency of some of the whistler mode waves. On the basis of high time resolution particle data from the Polar HYDRA instrument, we show that these bursts are consistent with generation by the resistive medium instability. The most likely source of the whistler mode waves is the magnetic reconnection site closest to the spacecraft, since the waves are observed propagating both toward and away from the Earth, are bursty, which is often the case with reconnection, and do not fit on the theoretical cold plasma dispersion relation curve.

Evaluation of Space Power Materials Flown on the Passive Optical Sample Assembly

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; deGroh, Kim K.; Skowronski, Timothy J.; McCollum, Tim; Pippin, Gary; Bungay, Corey

1999-01-01

Evaluating the performance of materials on the exterior of spacecraft is of continuing interest, particularly in anticipation of those applications that will require a long duration in low Earth orbit. The Passive Optical Sample Assembly (POSA) experiment flown on the exterior of Mir as a risk mitigation experiment for the International Space Station was designed to better understand the interaction of materials with the low Earth orbit environment and to better understand the potential contamination threats that may be present in the vicinity of spacecraft. Deterioration in the optical performance of candidate space power materials due to the low Earth orbit environment, the contamination environment, or both, must be evaluated in order to propose measures to mitigate such deterioration. The thirty two samples of space power materials studied here include solar array blanket materials such as polyimide Kapton H and SiO(x) coated polyimide Kapton H, front surface aluminized sapphire, solar dynamic concentrator materials such as silver on spin coated polyimide and aluminum on spin coated polyimide, CV 1144 silicone, and the thermal control paint Z-93-P. The physical and optical properties that were evaluated prior to and after the POSA flight include mass, total, diffuse, and specular reflectance, solar absorptance, and infrared emittance. Additional post flight evaluation included scanning electron microscopy to observe surface features caused by the low Earth orbit environment and the contamination environment, and variable angle spectroscopic ellipsometry to identify contaminant type and thickness. This paper summarizes the results of pre- and post-flight measurements, identifies the mechanisms responsible for optical properties deterioration, and suggests improvements for the durability of materials in future missions.

Enabling Technologies for Entrepreneurial Opportunities in 3D printing of SmallSats

NASA Technical Reports Server (NTRS)

Kwas, Andrew; MacDonald, Eric; Muse, Dan; Wicker, Ryan; Kief, Craig; Aarestad, Jim; Zemba, Mike; Marshall, Bill; Tolbert, Carol; Connor, Brett

2014-01-01

A consortium of innovative experts in additive manufacturing (AM) comprising Northrup Grumman Technical Services, University of Texas at El Paso (UTEP), Configurable Space Microsystems Innovations & Applications Center (COSMIAC), NASA Glenn Research Center (GRC), and Youngstown State University, have made significant breakthroughs in the goal of creating the first complete 3D printed small satellite. Since AM machines are relatively inexpensive, this should lead to many entrepreneurial opportunities for the small satellite community. Our technology advancements are focused on the challenges of embedding key components within the structure of the article. We have demonstrated, using advanced fused deposition modeling techniques, complex geometric shapes which optimize the spacecraft design. The UTEP Keck Center has developed a method that interrupts the printing process to insert components into specific cavities, resulting in a spacecraft that has minimal internal space allocated for what traditionally were functional purposes. This allows us to increase experiment and instrument capability by provided added volume in a confined small satellite space. Leveraging initial progress made on a NASA contract, the team investigated the potential of new materials that exploit the AM process, producing candidate compositions that exceed the capabilities of traditional materials. These "new materials" being produced and tested include some that have improved radiation shielding, increased permeability, enhanced thermal properties, better conductive properties, and increased structural performance. The team also investigated materials that were previously not possible to be made. Our testing included standard mechanical tests such as vibration, tensile, thermal cycling, and impact resistance as well as radiation and electromagnetic tests. The initial results of these products and their performance will be presented and compared with standard properties. The new materials with the highest probability to disrupt the future of small satellite systems by driving down costs will be highlighted, in conjunction with the electronic embedding process.

Stardust Interstellar Preliminary Examination V: XRF Analyses of Interstellar Dust Candidates at ESRF ID13

NASA Technical Reports Server (NTRS)

Brenker, Frank E.; Westphal, Andrew J.; Simionovici, Alexandre S.; Flynn, George J.; Gainsforth, Zack; Allen, Carlton C.; Sanford, Scott; Zolensky, Michael E.; Bastien, Ron K.; Frank, David R.

2014-01-01

Here, we report analyses by synchrotron X-ray fluorescence microscopy of the elemental composition of eight candidate impact features extracted from the Stardust Interstellar Dust Collector (SIDC). Six of the features were unambiguous tracks, and two were crater-like features. Five of the tracks are so-called midnight tracks that is, they had trajectories consistent with an origin either in the interstellar dust stream or as secondaries from impacts on the Sample Return Capsule (SRC). In a companion paper reporting synchrotron X-ray diffraction analyses of ISPE candidates, we show that two of these particles contain natural crystalline materials: the terminal particle of track 30contains olivine and spinel, and the terminal particle of track 34 contains olivine. Here, we show that the terminal particle of track 30, Orion, shows elemental abundances, normalized to Fe, that are close to CI values, and a complex, fine-grained structure. The terminal particle of track 34, Hylabrook, shows abundances that deviate strongly from CI, but shows little fine structure and is nearly homogenous. The terminal particles of other midnight tracks, 29 and 37, had heavy element abundances below detection threshold. A third, track28, showed a composition inconsistent with an extraterrestrial origin, but also inconsistent with known spacecraft materials. A sixth track, with a trajectory consistent with secondary ejecta from an impact on one of the spacecraft solar panels, contains abundant Ce and Zn. This is consistent with the known composition of the glass covering the solar panel. Neither crater-like feature is likely to be associated with extraterrestrial materials. We also analyzed blank aerogel samples to characterize background and variability between aerogel tiles. We found significant differences in contamination levels and compositions, emphasizing the need for local background subtraction for accurate quantification.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batalha, Natalie M.; /San Jose State U.; Rowe, Jason F.

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

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Space station needs, attributes and architectural options study. Volume 7-2: Data book. Commercial missions

NASA Technical Reports Server (NTRS)

1983-01-01

The history of NASA's materials processing in space activities is reviewed. Market projections, support requirements, orbital operations issues, cost estimates and candidate systems (orbiter sortie flight, orbiter serviced free flyer, space station, space station serviced free flyer) for the space production of semiconductor crystals are examined. Mission requirements are identified for materials processing, communications missions, bioprocessing, and for transferring aviation maintenance training technology to spacecraft.

Lithium-Ion Battery Program Status

NASA Technical Reports Server (NTRS)

Surampudi, S.; Huang, C. K.; Smart, M.; Davies, E.; Perrone, D.; Distefano, S.; Halpert, G.

1996-01-01

The objective of this program is to develop rechargeable Li-ion cells for future NASA missions. Applications that would benefit from this project are: new millenium spacecraft; rovers; landers; astronaut equipment; and planetary orbiters. The approach of this program is: select electrode materials and electrolytes; identify failure modes and mechanisms and enhance cycle life; demonstrate Li-ion cell technology with liquid electrolyte; select candidate polymer electrolytes for Li-ion polymer cells; and develop Li-ion polymer cell technology.

Material Properties of Three Candidate Elastomers for Space Seals Applications

NASA Technical Reports Server (NTRS)

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

2010-01-01

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

High-Capacity Communications from Martian Distances Part 4: Assessment of Spacecraft Pointing Accuracy Capabilities Required For Large Ka-Band Reflector Antennas

NASA Technical Reports Server (NTRS)

Hodges, Richard E.; Sands, O. Scott; Huang, John; Bassily, Samir

2006-01-01

Improved surface accuracy for deployable reflectors has brought with it the possibility of Ka-band reflector antennas with extents on the order of 1000 wavelengths. Such antennas are being considered for high-rate data delivery from planetary distances. To maintain losses at reasonable levels requires a sufficiently capable Attitude Determination and Control System (ADCS) onboard the spacecraft. This paper provides an assessment of currently available ADCS strategies and performance levels. In addition to other issues, specific factors considered include: (1) use of "beaconless" or open loop tracking versus use of a beacon on the Earth side of the link, and (2) selection of fine pointing strategy (body-fixed/spacecraft pointing, reflector pointing or various forms of electronic beam steering). Capabilities of recent spacecraft are discussed.

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

NASA Astrophysics Data System (ADS)

Cichocki, Filippo; Merino, Mario; Ahedo, Eduardo

2018-05-01

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

The Space Radiation Environment as it Relates to Electronic System Performance: Or Why Not to Fly Commercial Electronic Components in Space

NASA Technical Reports Server (NTRS)

Barth, Janet L.; Xapsos, Michael A.; LaBel, Kenneth A.; Polvey, Christian

2005-01-01

This viewgraph presentation offers an overview of the space radiation environment, primarily in near-Earth environments such as Low Earth Orbit (LEO). The presentation describes the Halloween solar event of 2003 as an example of how solar activity can affect spacecraft electronic systems. The lunar radiation environment is also briefly summarized.

Trajectory options for the DART mission

NASA Astrophysics Data System (ADS)

Atchison, Justin A.; Ozimek, Martin T.; Kantsiper, Brian L.; Cheng, Andrew F.

2016-06-01

This study presents interplanetary trajectory options for the Double Asteroid Redirection Test (DART) spacecraft to reach the near Earth object, Didymos binary system, during its 2022 Earth conjunction. DART represents a component of a joint NASA-ESA mission to study near Earth object kinetic impact deflection. The DART trajectory must satisfy mission objectives for arrival timing, geometry, and lighting while minimizing launch vehicle and spacecraft propellant requirements. Chemical propulsion trajectories are feasible from two candidate launch windows in late 2020 and 2021. The 2020 trajectories are highly perturbed by Earth's orbit, requiring post-launch deep space maneuvers to retarget the Didymos system. Within these windows, opportunities exist for flybys of additional near Earth objects: Orpheus in 2021 or 2007 YJ in 2022. A second impact attempt, in the event that the first impact is unsuccessful, can be added at the expense of a shorter launch window and increased (∼3x) spacecraft ΔV . However, the second impact arrival geometry has poor lighting, high Earth ranges, and would require additional degrees of freedom for solar panel and/or antenna gimbals. A low-thrust spacecraft configuration increases the trajectory flexibility. A solar electric propulsion spacecraft could be affordably launched as a secondary spacecraft in an Earth orbit and spiral out to target the requisite interplanetary departure condition. A sample solar electric trajectory was constructed from an Earth geostationary transfer using a representative 1.5 kW thruster. The trajectory requires 9 months to depart Earth's sphere of influence, after which its interplanetary trajectory includes a flyby of Orpheus and a second Didymos impact attempt. The solar electric spacecraft implementation would impose additional bus design constraints, including large solar arrays that could pose challenges for terminal guidance. On the basis of this study, there are many feasible options for DART to meet its mission design objectives and enable this unique kinetic impact experiment.

Liquid Rocket Booster (LRB) for the Space Transportion System (STS) systems study. Appendix D: Trade study summary for the liquid rocket booster

NASA Technical Reports Server (NTRS)

1989-01-01

Trade studies plans for a number of elements in the Liquid Rocket Booster (LRB) component of the Space Transportation System (STS) are given in viewgraph form. Some of the elements covered include: avionics/flight control; avionics architecture; thrust vector control studies; engine control electronics; liquid rocket propellants; propellant pressurization systems; recoverable spacecraft; cryogenic tanks; and spacecraft construction materials.

Annual Conference on Nuclear and Space Radiation Effects, 21st, Colorado Springs, CO, July 23-25, 1984, Proceedings

NASA Technical Reports Server (NTRS)

Winokur, P. S. (Editor)

1984-01-01

Radiation effects on electronic systems and devices (particularly spacecraft systems) are examined with attention given to such topics as radiation transport, energy deposition, and charge collection; single-event phenomena; basic mechanisms of radiation effects in structures and materials; and EMP phenomena. Also considered are radiation effects in integrated circuits, spacecraft charging and space radiation effects, hardness assurance for devices and systems, and SGEMP/IEMP phenomena.

CINEMA (Cubesat for Ion, Neutral, Electron, MAgnetic fields)

NASA Astrophysics Data System (ADS)

Lin, R. P.; Parks, G. K.; Halekas, J. S.; Larson, D. E.; Eastwood, J. P.; Wang, L.; Sample, J. G.; Horbury, T. S.; Roelof, E. C.; Lee, D.; Seon, J.; Hines, J.; Vo, H.; Tindall, C.; Ho, J.; Lee, J.; Kim, K.

2009-12-01

The NSF-funded CINEMA mission will provide cutting-edge magnetospheric science and critical space weather measurements, including high sensitivity mapping and high cadence movies of ring current, >4 keV Energetic Neutral Atom (ENA), as well as in situ measurements of suprathermal electrons (>~2 keV) and ions (>~ 4 keV) in the auroral and ring current precipitation regions, all with ~1 keV FWHM resolution and uniform response up to ~100 keV. A Suprathermal Electron, Ion, Neutral (STEIN) instrument adds an electrostatic deflection system to the STEREO STE (SupraThermal Electron) 4-pixel silicon semiconductor sensor to separate ions from electrons and from ENAs up to ~20 keV. In addition, inboard and outboard (on an extendable 1m boom) magnetoresistive sensor magnetometers will provide high cadence 3-axis magnetic field measurements. A new attitude control system (ACS) uses torque coils, a solar aspect sensor and the magnetometers to de-tumble the 3u CINEMA spacecraft, then spin it up to ~1 rpm with the spin axis perpendicular to the ecliptic, so STEIN can sweep across most of the sky every minute. Ideally, CINEMA will be placed into a high inclination low earth orbit that crosses the auroral zone and cusp. An S-band transmitter will be used to provide > ~8 kbps orbit-average data downlink to the ~11m diameter antenna of the Berkeley Ground Station. Two more identical CINEMA spacecraft will be built by Kyung Hee University (KHU) in Korea under their World Class University (WCU) program, to provide stereo ENA imaging and multi-point in situ measurements. Furthermore, CINEMA’s development of miniature particle and magnetic field sensors, and cubesat-size spinning spacecraft will be important for future nanosatellite space missions.

Ground/bonding for Large Space System Technology (LSST). [of metallic and nonmetallic structures

NASA Technical Reports Server (NTRS)

Dunbar, W. G.

1980-01-01

The influence of the environment and extravehicular activity remote assembly operations on the grounding and bonding of metallic and nonmetallic structures is discussed. Grounding and bonding philosophy is outlined for the electrical systems and electronic compartments which contain high voltage, high power electrical and electronic equipment. The influence of plasma and particulate on the system was analyzed and the effects of static buildup on the spacecraft electrical system discussed. Conceptual grounding bonding designs are assessed for capability to withstand high current arcs to ground from a high voltage conductor and electromagnetic interference. Also shown were the extravehicular activities required of the space station and or supply spacecraft crew members to join and inspect the ground system using manual on remote assembly construction.

Observations of Large-Amplitude, Parallel, Electrostatic Waves Associated with the Kelvin-Helmholtz Instability by the Magnetospheric Multiscale Mission

NASA Technical Reports Server (NTRS)

Wilder, F. D.; Ergun, R. E.; Schwartz, S. J.; Newman, D. L.; Eriksson, S.; Stawarz, J. E.; Goldman, M. V.; Goodrich, K. A.; Gershman, D. J.; Malaspina, D.;

Radiation effects measurements on spacecraft electrostatic discharge tapes, thermal blankets and thermooptical coatings

NASA Technical Reports Server (NTRS)

Bouquet, F. L.; Hribar, V. F.; Metzler, E. C.; Russell, D. A.

1984-01-01

Selective results are presented of laboratory radiation tests of metallic foil tapes, thermal blankets, and thermooptical coatings undertaken as part of the development and qualification of materials for the Galileo spacecraft. Of the two metallic foil tapes used for electrical continuity, the adhesive used on the aluminum embossed foil was superior to the copper embossed foil when exposed to simulated Jovian electrons. Proton-irradiation tests performed on a number of thermal blanket samples showed that black polyester on Kapton proved to be a lower weight loss (i.e., outgassing) material than Fluorglas. In addition, preliminary results concerning the response of thermooptical coatings to simulated Jovian electrons show that the ITO-coated polyester over a Kapton surface gave the lowest absorptance.

Ground/bonding for Large Space System Technology (LSST)

NASA Astrophysics Data System (ADS)

Dunbar, W. G.

1980-04-01

The influence of the environment and extravehicular activity remote assembly operations on the grounding and bonding of metallic and nonmetallic structures is discussed. Grounding and bonding philosophy is outlined for the electrical systems and electronic compartments which contain high voltage, high power electrical and electronic equipment. The influence of plasma and particulate on the system was analyzed and the effects of static buildup on the spacecraft electrical system discussed. Conceptual grounding bonding designs are assessed for capability to withstand high current arcs to ground from a high voltage conductor and electromagnetic interference. Also shown were the extravehicular activities required of the space station and or supply spacecraft crew members to join and inspect the ground system using manual on remote assembly construction.

The Sheath-less Planar Langmuir Probe

NASA Astrophysics Data System (ADS)

Cooke, D. L.

2017-12-01

The Langmuir probe is one of the oldest plasma diagnostics, provided the plasma density and species temperature from analysis of a current-voltage curve as the voltage is swept over a practically chosen range. The analysis depends on a knowledge or theory of the many factors that influence the current-voltage curve including, probe shape, size, nearby perturbations, and the voltage reference. For applications in Low Earth Orbit, the Planar Langmuir Probe, PLP, is an attractive geometry because the ram ion current is very constant over many Volts of a sweep, allowing the ion density and electron temperature to be determined independently with the same instrument, at different points on the sweep. However, when the physical voltage reference is itself small and electrically floating as with a small spacecraft, the spacecraft and probe system become a double probe where the current collection theory depends on the interaction of the spacecraft with the plasma which is generally not as simple as the probe itself. The Sheath-less PLP, SPLP, interlaces on a single ram facing surface, two variably biased probe elements, broken into many small and intertwined segments on a scale smaller than the plasma Debye length. The SPLP is electrically isolated from the rest of the spacecraft. For relative bias potentials of a few volts, the ion current to all segments of each element will be constant, while the electron currents will vary as a function of the element potential and the electron temperature. Because the segments are small, intertwined, and floating, the assembly will always present the same floating potential to the plasma, with minimal growth as a function of voltage, thus sheath-less and still planar. This concept has been modelled with Nascap, and tested with a physical model inserted into a Low Earth Orbit-like chamber plasma. Results will be presented.

Practical Applications of Cosmic Ray Science: Spacecraft, Aircraft, Ground Based Computation and Control Systems and Human Health and Safety

NASA Technical Reports Server (NTRS)

Atwell, William; Koontz, Steve; Normand, Eugene

2012-01-01

In this paper we review the discovery of cosmic ray effects on the performance and reliability of microelectronic systems as well as on human health and safety, as well as the development of the engineering and health science tools used to evaluate and mitigate cosmic ray effects in earth surface, atmospheric flight, and space flight environments. Three twentieth century technological developments, 1) high altitude commercial and military aircraft; 2) manned and unmanned spacecraft; and 3) increasingly complex and sensitive solid state micro-electronics systems, have driven an ongoing evolution of basic cosmic ray science into a set of practical engineering tools (e.g. ground based test methods as well as high energy particle transport and reaction codes) needed to design, test, and verify the safety and reliability of modern complex electronic systems as well as effects on human health and safety. The effects of primary cosmic ray particles, and secondary particle showers produced by nuclear reactions with spacecraft materials, can determine the design and verification processes (as well as the total dollar cost) for manned and unmanned spacecraft avionics systems. Similar considerations apply to commercial and military aircraft operating at high latitudes and altitudes near the atmospheric Pfotzer maximum. Even ground based computational and controls systems can be negatively affected by secondary particle showers at the Earth's surface, especially if the net target area of the sensitive electronic system components is large. Accumulation of both primary cosmic ray and secondary cosmic ray induced particle shower radiation dose is an important health and safety consideration for commercial or military air crews operating at high altitude/latitude and is also one of the most important factors presently limiting manned space flight operations beyond low-Earth orbit (LEO).

Combined space environment on spacecraft engineering materials

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

System status display information

NASA Technical Reports Server (NTRS)

Summers, L. G.; Erickson, J. B.

1984-01-01

The system Status Display is an electronic display system which provides the flight crew with enhanced capabilities for monitoring and managing aircraft systems. Guidelines for the design of the electronic system displays were established. The technical approach involved the application of a system engineering approach to the design of candidate displays and the evaluation of a Hernative concepts by part-task simulation. The system engineering and selection of candidate displays are covered.

Space Weather Impacts on Spacecraft Design and Operations in Auroral Charging Environments

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Parker, Linda N.

2012-01-01

Spacecraft in low altitude, high inclination (including sun-synchronous) orbits are widely used for remote sensing of the Earth s 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 are episodically exposed to environments characterized by a high flux of energetic (approx.1 to 10 s kilovolt) electrons in regions of very low background plasma density which is similar in some ways to the space weather conditions in geostationary orbit responsible for spacecraft charging to kilovolt levels. While it is well established that charging conditions in geostationary orbit are responsible for many anomalies and even spacecraft failures, to date there have been relatively few such reports due to charging in auroral environments. This presentation first reviews the physics of the space environment and its 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 and discuss how space weather impacts both spacecraft design and operations for vehicles on orbital trajectories that traverse auroral charging environments.

Analysis of GEO spacecraft anomalies: Space weather relationships

NASA Astrophysics Data System (ADS)

Choi, Ho-Sung; Lee, Jaejin; Cho, Kyung-Suk; Kwak, Young-Sil; Cho, Il-Hyun; Park, Young-Deuk; Kim, Yeon-Han; Baker, Daniel N.; Reeves, Geoffrey D.; Lee, Dong-Kyu

2011-06-01

While numerous anomalies and failures of spacecraft have been reported since the beginning of the space age, space weather effects on modern spacecraft systems have been emphasized more and more with the increase of their complexity and capability. However, the relationship between space weather and commercial satellite anomalies has not been studied extensively. In this paper, we investigate the geostationary Earth orbit (GEO) satellite anomalies archived by Satellite News Digest during 1997-2009 in order to search for possible influences of space weather on the anomaly occurrences. We analyze spacecraft anomalies for the Kp index, local time, and season and then compare them with the tendencies of charged particles observed by Los Alamos National Laboratory (LANL) satellites. We obtain the following results: (1) there are good relationships between geomagnetic activity (as measured by the Kp index) and anomaly occurrences of the GEO satellites; (2) the satellite anomalies occurred mainly in the midnight to morning sector; and (3) the anomalies are found more frequently in spring and fall than summer and winter. While we cannot fully explain how space weather is involved in producing such anomalies, our analysis of LANL data shows that low-energy (<100 keV) electrons have similar behaviors with spacecraft anomalies and implies the spacecraft charging might dominantly contribute to the GEO spacecraft anomalies reported in Satellite News Digest.

Using FLUKA to Calculate Spacecraft: Single Event Environments: A Practical Approach

NASA Technical Reports Server (NTRS)

Koontz, Steve; Boeder, Paul; Reddell, Brandon

2009-01-01

The FLUKA nuclear transport and reaction code can be developed into a practical tool for calculation of spacecraft and planetary surface asset SEE and TID environments. Nuclear reactions and secondary particle shower effects can be estimated with acceptable accuracy both in-flight and in test. More detailed electronic device and/or spacecraft geometries than are reported here are possible using standard FLUKA geometry utilities. Spacecraft structure and shielding mass. Effects of high Z elements in microelectronic structure as reported previously. Median shielding mass in a generic slab or concentric sphere target geometry are at least approximately applicable to more complex spacecraft shapes. Need the spacecraft shielding mass distribution function applicable to the microelectronic system of interest. SEE environment effects can be calculated for a wide range of spacecraft and microelectronic materials with complete nuclear physics. Evaluate benefits of low Z shielding mass can be evaluated relative to aluminum. Evaluate effects of high Z elements as constituents of microelectronic devices. The principal limitation on the accuracy of the FLUKA based method reported here are found in the limited accuracy and incomplete character of affordable heavy ion test data. To support accurate rate estimates with any calculation method, the aspect ratio of the sensitive volume(s) and the dependence must be better characterized.

Communications Blackout Prediction for Atmospheric Entry of Mars Science Laboratory

NASA Technical Reports Server (NTRS)

Morabito, David; Edquist, Karl

2005-01-01

When a supersonic spacecraft enters a planetary atmosphere with v >> v(sub sound), a shock layer forms in the front of the body. An ionized sheath of plasma develops around the spacecraft, which results from the ionization of the atmospheric constituents as they are compressed and heated by the shock or heated within the boundary layer next to the surface. When the electron density surrounding the spacecraft becomes sufficiently high, communications can be disrupted (attenuation/blackout). During Mars Science Laboratory's (MSL's) atmospheric entry there will likely be a communication outage due to charged particles on the order of 60 to 100 seconds using a UHF link frequency looking out the shoulders of the wake region to orbiting relay asset. A UHF link looking out the base region would experience a shorter duration blackout, about 35 seconds for the stressed trajectory and possibly no blackout for the nominal trajectory. There is very little likelihood of a communications outage using X-band (however, X-band is not currently planned to be used during peak electron density phase of EDL).

Adverse Space Weather at the Solar Cycle Minimum

NASA Astrophysics Data System (ADS)

Baker, D. N.; Kanekal, S. G.; McCollough, J. P.; Singer, H. J.; Chappell, S. P.; Allen, J. H.

2008-05-01

It is commonly understood that many types of adverse space weather (solar flares, coronal mass ejections, geomagnetic storms) occur most commonly around the maximum of the 11-year sunspot activity cycle. Other types of well-known space weather such as relativistic electron events in the Earth's outer magnetosphere (that produce deep dielectric charging in spacecraft systems) are usually associated with the period just after sunspot maximum. At the present time, we are in the very lowest activity phase of the sunspot cycle (solar minimum). As such we would not expect much in the way of adverse space weather events. However, in early to mid-February of 2008 quite prominent solar coronal holes produced two high-speed streams that in turn stimulated very large, long-duration relativistic electron enhancements in Earth's magnetosphere. These seem to have been associated with several spacecraft operational anomalies at various spacecraft orbital locations. We describe these recent space weather events and assess their operational significance in this presentation. These results show that substantial space weather events can and do occur even during the quietest parts of the solar cycle.

Profiles of electron temperature and Bz along Earth's magnetotail

NASA Astrophysics Data System (ADS)

Artemyev, A. V.; Petrukovich, A. A.; Nakamura, R.; Zelenyi, L. M.

2013-06-01

We study the electron temperature distribution and the structure of the current sheet along the magnetotail using simultaneous observations from THEMIS spacecraft. We perform a statistical study of 40 crossings of the current sheet when the three spacecraft THB, THC, and THD were distributed along the tail in the vicinity of midnight with coordinates XB \\in [-30 RE, -20 RE], XC \\in [-20 RE, -15 RE], and XD ~ -10 RE. We obtain profiles of the average electron temperature \\mlab Te\\mrab and the average magnetic field \\mlab Bz\\mrab along the tail. Electron temperature and \\mlab Bz\\mrab increase towards the Earth with almost the same rates (i.e., ratio \\mlab Te\\mrab/\\mlab Bz\\mrab ≈ 2 keV/7 nT is approximately constant along the tail). We also use statistics of 102 crossings of the current sheet from THB and THC to estimate dependence of Te and Bz distributions on geomagnetic activity. The ratio \\mlab Te \\mrab/\\mlab Bz\\mrab depends on geomagnetic activity only slightly. Additionally we demonstrate that anisotropy of the electron temperature \\mlab T∥/T⊥\\mrab ≈ 1.1 is almost constant along the tail for X \\in [-30 RE, -10 RE].

Augmentation method of XPNAV in Mars orbit based on Phobos and Deimos observations

NASA Astrophysics Data System (ADS)

Rong, Jiao; Luping, Xu; Zhang, Hua; Cong, Li

2016-11-01

Autonomous navigation for Mars probe spacecraft is required to reduce the operation costs and enhance the navigation performance in the future. X-ray pulsar-based navigation (XPNAV) is a potential candidate to meet this requirement. This paper addresses the use of the Mars' natural satellites to improve XPNAV for Mars probe spacecraft. Two observation variables of the field angle and natural satellites' direction vectors of Mars are added into the XPNAV positioning system. The measurement model of field angle and direction vectors is formulated by processing satellite image of Mars obtained from optical camera. This measurement model is integrated into the spacecraft orbit dynamics to build the filter model. In order to estimate position and velocity error of the spacecraft and reduce the impact of the system noise on navigation precision, an adaptive divided difference filter (ADDF) is applied. Numerical simulation results demonstrate that the performance of ADDF is better than Unscented Kalman Filter (UKF) DDF and EKF. In view of the invisibility of Mars' natural satellites in some cases, a visibility condition analysis is given and the augmented XPNAV in a different visibility condition is numerically simulated. The simulation results show that the navigation precision is evidently improved by using the augmented XPNAV based on the field angle and natural satellites' direction vectors of Mars in a comparison with the conventional XPNAV.

Studies of auroral X-ray imaging from high altitude spacecraft

NASA Technical Reports Server (NTRS)

Mckenzie, D. L.; Mizera, P. F.; Rice, C. J.

1980-01-01

Results of a study of techniques for imaging the aurora from a high altitude satellite at X-ray wavelengths are summarized. The X-ray observations allow the straightforward derivation of the primary auroral X-ray spectrum and can be made at all local times, day and night. Five candidate imaging systems are identified: X-ray telescope, multiple pinhole camera, coded aperture, rastered collimator, and imaging collimator. Examples of each are specified, subject to common weight and size limits which allow them to be intercompared. The imaging ability of each system is tested using a wide variety of sample spectra which are based on previous satellite observations. The study shows that the pinhole camera and coded aperture are both good auroral imaging systems. The two collimated detectors are significantly less sensitive. The X-ray telescope provides better image quality than the other systems in almost all cases, but a limitation to energies below about 4 keV prevents this system from providing the spectra data essential to deriving electron spectra, energy input to the atmosphere, and atmospheric densities and conductivities. The orbit selection requires a tradeoff between spatial resolution and duty cycle.