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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
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NASA NTRS1978

Sound Guard

Lubrication technology originally developed for a series of NASA satellites has produced a commercial product for protecting the sound fidelity of phonograph records. Called Sound Guard, the preservative is a spray-on fluid that deposits a microscopically thin protective coating which reduces friction and prevents the hard diamond stylus from wearing away the softer vinyl material of the disc. It is marketed by the Consumer Products Division of Ball Corporation, Muncie, Indiana. The lubricant technology on which Sound Guard is based originated with NASA's Orbiting Solar Observatory (OSO), an Earth-orbiting satellite designed and built by Ball Brothers Research Corporation, Boulder, Colorado, also a division of Ball Corporation. Ball Brothers engineers found a problem early in the OSO program: known lubricants were unsuitable for use on satellite moving parts that would be exposed to the vacuum of space for several months. So the company conducted research on the properties of materials needed for long life in space and developed new lubricants. They worked successfully on seven OSO flights and attracted considerable attention among other aerospace contractors. Ball Brothers now supplies its "Vac Kote" lubricants and coatings to both aerospace and non-aerospace industries and the company has produced several hundred variations of the original technology. Ball Corporation expanded its product line to include consumer products, of which Sound Guard is one of the most recent. In addition to protecting record grooves, Sound Guard's anti-static quality also retards particle accumulation on the stylus. During comparison study by a leading U.S. electronic laboratory, a record not treated by Sound Guard had to be cleaned after 50 plays and the stylus had collected a considerable number of small vinyl particles. The Sound Guard-treated disc was still clean after 100 plays, as was its stylus.

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NASA NTRS2019

Full Inversion of Solar Relativistic Electron Events Measured by the Helios Spacecraft

The Parker Solar Probe and the incoming Solar Orbiter mission will provide measurements of solar energetic particle (SEP) events at close heliocentric distances from the Sun. Up to present, the largest data set of SEP events in the inner heliosphere are the observations by the two Helios spacecraft. Aims.We re-visit a sample of 15 solar relativistic electron events measured by the Helios mission with the goal of better characterizing the injection histories of solar energetic particles and their interplanetary transport conditions at heliocentric distances <1AU. Methods. The measurements provided by the E6 instrument on board Helios provide us with the electron directional distributionsin eight di erent sectors that we use to infer the detailed evolution of the electron pitch-angle distributions. The results of a Monte Carlo interplanetary transport model, combined with a full inversion procedure, were used to fit the observed directional intensities in the 300–800 keV nominal energy channel. Unlike previous studies, we have considered both the energy and angular responses of the detector. This method allowed us to infer the electron release time profile at the source and determine the electron interplanetary transport conditions. Results. We discuss the duration of the release time profiles and the values of the radial mean free path, and compare them with thevalues reported previously in the literature using earlier approaches. Five of the events show short injection histories (<30 min) at the Sun and ten events show long-lasting (>30 min) injections. The values of mean free path range from 0.02AU to 0.27AU.Conclusions. The inferred injection histories match with the radio and soft X-ray emissions found in literature.We find no dependence of the radial mean free path on the radial distance. In addition, we find no apparent relation between the strength of interplanetary scattering and the size of the solar particle release.

Pacheco, D.↗
NASA NTRS1978

Disposal of radioactive iodine in space

The possibility of space disposal of iodine waste from nuclear power reactors is investigated. The space transportation system utilized relies upon the space shuttle, a liquid hydrogen/liquid oxygen orbit transfer vehicle, and a solid propellant final stage. The iodine is assumed to be in the form of either an iodide or an iodate, and calculations assume that the final destination is either solar orbit or solar system escape. It is concluded that space disposal of iodine is feasible.

Burns, R. E.↗
NASA NTRS1981

Estimation of solar gravitational harmonics with Starprobe radiometric tracking data

The potential gravitational science return of a proposed spacecraft mission, called Starprobe, is investigated. The current mission plan is to place a spacecraft in a highly eccentric, highly inclined solar orbit with a perihelion distance of four solar radii. A covariance analysis based on Kalman filtering theory is performed to predict the accuracies with which gravitational parameters associated with the nonsphericity of the sun and relativistic effects can be estimated with radiometric tracking data. The accuracies are computed as functions of the quality and quantity of the radiometric data, the orbital parameters, the magnitude and character of the nongravitational accelerations acting on the spacecraft, and the errors in the tracking station locations and the ephemeris of the earth relative to the sun.

Mease, K. D.↗
NASA NTRS1995

LDEF's contribution to the selection of thermal control coatings for the Space Station

The design of the Space Station presented new challenges in the selection and qualification of thermal control materials that would survive in low Earth orbit for a duration of up to 30 years. Prior to LDEF, flight data were obtained from Orbiting Solar Observatory (OSO) satellites, a number of Orbiter flights, and limited ground tests. The excellent data obtained from the OSO satellites were based on calorimetry and temperature measurements which were transmitted to Earth; these satellites were not recovered. For some of these flight experiments it was difficult to distinguish between changes due to contamination, atomic oxygen (AO), ultraviolet radiation (UV), particle radiation and the synergistic effects between them. The data from Shuttle flights were primarily focused on developing a better understanding of atomic oxygen (AO) effects. Although UV and AO were present, the relatively short duration of the Orbiter flights, about one week, was viewed as too short to show the effects from UV or possible synergistic interactions with AO and contamination. At the beginning of the program in 1989 there was no established design data base for AO resistant thermal control coatings for the Space Station. Then came the Long Duration Exposure Facility (LDEF). It provided the first long life data for materials exposed and recovered from space with a characterized environment. Post flight analysis proved data on the effects of contamination on optical properties in the ram (velocity) and wake directions and the erosion of Teflon and multilayer insulation (MLI) covers. The results from LDEF confirmed and, in some cases, modified the approach used for the Space Station, as well as helped to focus our development activities. These development activities resulted in a number of new technical solutions which are applicable to many spacecraft surfaces and missions. LDEF also showed the detrimental effects that could occur from silicone contamination, an issue that has not been completely resolved. An investigation was initiated in 1993 on the effects of silicone contamination and was continuing at the time this paper was prepared.

Babel, Henry W.↗
NASA NTRS1977

Earth orbital assessment of solar electric and solar sail propulsion systems

The earth orbital applications potential of Solar Electric (Ion Drive) and Solar Sail low-thrust propulsion systems are evaluated. Emphasis is placed on mission application in the 1980s. The two low-thrust systems are compared with each other and with two chemical propulsion Shuttle upper stages (the IUS and SSUS) expected to be available in the 1980s. The results indicate limited Earth orbital application potential for the low-thrust systems in the 1980s (primarily due to cost disadvantages). The longer term potential is viewed as more promising. Of the two systems, the Ion Drive exhibits better performance and appears to have better overall application potential.

Teeter, R. R.↗
NASA NTRS1990

Solar minimum Lyman alpha sky background observations from Pioneer Venus orbiter ultraviolet spectrometer - Solar wind latitude variation

Measurements of interplanetary H I Lyman alpha over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar system shows that the rate of charge exchange with solar wind protons is 30 percent less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum.

Ajello, J. M.↗
NASA NTRS2011

Effects of Low Activity Solar Cycle on Orbital Debris Lifetime

Long duration of low solar activity in the last solar minimum has an undesirable consequence of extending the lifetime of orbital debris. The AFRL TacSat-2 satellite decommissioned in 2008 has finally re-entered into the atmosphere on February 5th after more than one year overdue. Concerning its demise we have monitored its orbital decay and monthly forecasted Tacsat-2 re-entry since September 2010 by using the Orbital Element Prediction (OEP) model developed by the AFRL Orbital Drag Environment program. The model combines estimates of future solar activity with neutral density models, drag coefficient models, and an orbit propagator to predict satellite lifetime. We run the OEP model with solar indices forecast by the NASA Marshall Solar Activity Future Estimation model, and neutral density forecast by the MSIS-00 neutral density model. Based on the two line elements in 2010 up to mid September, we estimated at a 50% confidence level TacSat-2's re-entry time to be in early February 2011, which turned out to be in good agreement with Tacsat-2's actual re-entry date. The potential space weather effects of the coming low activity solar cycle on satellite lifetime and orbital debris population are examined. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of solar flux on the orbital debris population in the 200-600 km altitude environment. The results are discussed for developing satellite orbital drag application product.

Cable, Samual B.↗
NASA NTRS1980

Study of multi-kW solar arrays for Earth orbit application

Low cost low Earth orbit (LOW) and geosynchronous Earth orbit (GEO) Solar Array concepts in the 300 to 1000 kW range which could be reduced to hardware in the mid 1980's, are identified. Size scaling factors and longer life demands are recognized as the prime drivers for the designs if low life cycle costs for energy are to be achieved. Technology is identified which requires further development in order to assure component readiness and availability. Use of the low concentration ratio (CR) concentrator, which uses gallium arsenide solar cells for both LEO and GEO applications, is recommended.

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NASA NTRS1991

Human exploration of space and power development

Reasons for mounting the Space Exploration Initiative, the variables facing U.S. planners, and the developmental technologies that will be needed to support this initiative are discussed. The three more advanced technological approaches in the field of power generation described include a lunar-based solar power system, a geosynchronous-based earth orbit solar power satellite system, and the utilization of helium-3/deuterium fusion reaction to create a nuclear fuel cycle. It is noted that the major elements of the SEI will include a heavy-lift launch vehicle, a transfer vehicle and a descent/ascent vehicle for use on lunar missions and adaptable to Mars exploration.

Cohen, Aaron↗
NASA NTRS2016

Mars Sample Thermal Control During Mars Ascent and Orbit

Although NASA has no official plans at this time for a mission to return samples from Mars, the Program Formulation Office of the Mars Exploration Program sponsors ongoing mission concept studies, systems analyses, and technology investments which explore different strategies for the potential return of samples from Mars, consistent with the charter of the program and stated priorities of the science community. Maintaining the thermal integrity of collected samples would be very important. In general, samples would be collected, sealed inside tubes, and left on the surface for later retrieval. They would then be inserted into an OS (Orbiting Sample), and carried to a Mars or Solar orbit via a MAV (Mars Ascent Vehicle). Subsequently, an Earth return vehicle would rendezvous with the OS and bring it back to Earth. During ascent from Mars, the OS could serve as the nose cone of the MAV and would be subjected to significant aerodynamic heating from the Martian atmosphere. Once the OS is released from the MAV, its external surface would be exposed to potentially several years of sunlight, eclipse, planetary IR, albedo, and space. The challenge is to ensure that these samples are kept at thermally moderate conditions to preserve their integrity in these widely different environments. Various thermal techniques have been investigated to achieve sample thermal control: use of thermal protection shields and surfaces (ablative and non-ablative) to protect them from adverse exposure to ascent heating, as well combinations of thermo-optical coatings during the orbital phase. The work described herein is part of this ongoing effort & will describe the key challenges related to the thermal control of the potential Mars samples during these phases and the corresponding schemes to overcome them.

Bhandari, Pradeep↗
NASA NTRS1975

Relativity experiment on Helios - A status report

The relativity experiment on Helios (Experiment 11) uses S-band and Doppler data, and spacecraft-solar-orbital data to measure the effects of general relativity in the solar system and the quadrupole moment in the solar gravitational field. Specifically, Experiment 11 is converned with measuring the following effects: (1) relativistic orbital corrections described by two parameters of the space-time metric which are both equal to unity in Einstein's theory; (2) orbital perturbations caused by a finite quadrupole moment of an oblate sun, described by zonal harmonics in the solar gravitational field.

Anderson, J. D.↗
NASA NTRS2007

Characterization of MODIS Solar Diffuser On-orbit Degradation

MODIS reflective solar bands (RSB) are calibrated on-orbit by a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). The SD bi-directional reflectance factor (BRF) was characterized pre-launch by the instrument vendor using reference samples traceable to NIST reflectance standards. Its on-orbit degradation is regularly monitored by the SDSM. It consists of a solar integration sphere (SIS) with 9 filtered detectors with wavelengths ranging from 0.41 to 0.94 micrometer, a rotating mirror assembly, and an electronics module. During each SD/SDSM calibration, the SDSM views the sunlight directly and the sunlight diffusely reflected from the SD panel. The time series of SDSM measurements (ratio of the SD view response to the Sun view response) is used to compute the SD BRF degradation at each SDSM detector wavelength. Since launch Terra MODIS has operated for more than seven years and Aqua for nearly five years. The SD panel on each MODIS instrument has experienced noticeable degradation with the largest changes observed in the VIS spectral region. Following a brief description of the MODIS RSB calibration methodology and SD/SDSM operational activities, this paper illustrates the SD on-orbit degradation results for both Terra and Aqua MODIS. It discusses the impacts on the SD RF degradation due to sensor operational conditions and SD solar exposure time. For Aqua MODIS, operated under the same conditions, the SD annual degradation rate is approximately 2.9% at 0.41 micrometers, 1.6% at 0.47 micrometers, and less than 1.1% at wavelengths above 0.53 micrometers. For Terra MODIS, however, an SD door (SDD) related anomaly in May 2003 had led to a decision to keep the SDD permanently at its open position. Since then its SD has experienced a much faster SD degradation rate.

Xiong, X.↗
NASA NTRS1982

Orbiter radiator panel solar focusing test

A test was conducted to determine the solar reflections from the Orbiter radiator panels. A one-tenth scale model of the forward and mid-forward radiator panels in the deployed position was utilized in the test. Test data was obtained to define the reflected one-sun envelope for the embossed silver/Teflon radiator coating. The effects of the double contour on the forward radiator panels were included in the test. Solar concentrations of 2 suns were measured and the one-sun envelope was found to extend approximately 86 inches above the radiator panel. A limited amount of test data was also obtained for the radiator panels with the smooth silver/Teflon coating to support the planned EVA on the Orbiter STS-5 flight. Reflected solar flux concentrations as high as 8 suns were observed with the smooth coating and the one-sun envelope was determined to extend 195 inches above the panel. It is recommended that additional testing be conducted to define the reflected solar environment beyond the one-sun boundary.

Howell, H. R.↗