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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 217 records · Page 12
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NASA NTRS1999

Hardware and Methods of the Optical End-to-End Test of the Far Ultraviolet Spectroscopic Explorer (FUSE)

The Far Ultraviolet Spectroscopic Explorer (FUSE), currently being tested and scheduled for a 1999 launch, is an astrophysics satellite designed to provide high spectral resolving power (Lambda/(Delta)Lambda = 24,000-30,000) over the interval 90.5-118.7 nm. The FUSE optical path consists of four co-aligned, normal incidence, off-axis parabolic, primary mirrors which illuminate separate Rowland circle spectrograph channels equipped with holographic gratings and delay line microchannel plate detectors. We describe the hardware and methods used for the optical end-to-end test of the FUSE instrument during satellite integration and test. Cost and schedule constraints forced us to devise a simplified version of the planned optical test which occurred in parallel with satellite thermal-vacuum testing. The optical test employed a collimator assembly which consisted of four co-aligned, 15" Cassegrain telescopes which were positioned above the FUSE instrument, providing a collimated beam for each optical channel. A windowed UV light source, remotely adjustable in three axes, was mounted at the focal plane of each collimator. Problems with the UV light sources, including high F-number and window failures, were the only major difficulties encountered during the test. The test succeeded in uncovering a significant problem with the secondary structure used for the instrument closeout cavity and, furthermore, showed that the mechanical solution was successful. The hardware was also used extensively for simulations of science observations, providing both UV light for spectra and visible light for the fine error sensor camera.

Conard, Steven J.↗
NASA NTRS1977

Application of altitude control techniques for low altitude earth satellites

The applications sensors of many low altitude earth satellites designed for recording surface or atmospheric data require near zero orbital eccentricities for maximum usefulness. Coverage patterns and altitude profiles require specified values of orbit semimajor axis. Certain initial combinations of semimajor axis, eccentricity, and argument of perigee can produce a so called 'frozen orbit' and minimum altitude variation which enhances sensor coverage. This paper develops information on frozen orbits and minimum altitude variation for all inclinations, generalizing previous results. In the altitude regions where most of these satellites function (between 200 and 1000 kilometers) strong atmospheric drag effects influence the evolution of the initial orbits. Active orbital maneuver control techniques to correct evolution of orbit parameters while minimizing the frequency of maneuvers are presented. The paper presents the application of theoretical techniques for control of near frozen orbits and expands upon the methods useful for simultaneously targeting several inplane orbital parameters. The applications of these techniques are illustrated by performance results from the Atmosphere Explorer (AE-3 and -5) missions and in preflight maneuver analysis and plans for the Seasat Oceanographic Satellite.

Nickerson, K. G.↗
NASA NTRS2024

A Survey of Modeling Activities by NASA’s Orbital Debris Program Office

NASA’s Orbital Debris Program Office (ODPO) develops and maintains a number of modeling tools to analyze and simulate the orbital debris environment. One of the most important products produced by the NASA ODPO is the Orbital Debris Engineering Model (ORDEM). This model can be used by satellite designers and operators to design missions for better protection against the debris environment. The ODPO is currently working on the next generation, designated ORDEM 4.0. ORDEM 4.0 will include many known features from previous models, such as the ability to input a spacecraft orbit and time and the ability to compute the flux as a function of debris size, impact speed, impact direction, and debris material densities, as well as uncertainty information on the flux. A new addition will be a parameterized debris shape model based on laboratory hypervelocity impact tests, including DebriSat. ORDEM is primarily based on dedicated debris measurements, such as by the Haystack Ultrawideband Satellite Imaging Radar (HUSIR), NASA’s Goldstone radar, and observations of geosynchronous orbits (GEO) using the Eugene Stansbery-Meter Class Autonomous Telescope (ES-MCAT). In addition to ORDEM, the ODPO also maintains other models, such as the LEO-to-GEO Environment Debris (LEGEND) model for studies of long-term evolution of Earth’s debris environment, with the ability to study various mitigation and remediation strategies. Another model, the Satellite Breakup Risk Assessment Model (SBRAM), is used to analyze how satellite breakups may affect critical space missions (such as the ISS) on short notice. In addition to these models, the ODPO maintains other secondary models used to model satellite explosions and collisions, analyze radar, optical, and in situ data, and to model such things as solar activity and orbit evolution. In this presentation, a survey of these models will be presented, showing how the different models are used together to create a comprehensive picture of Earth’s debris environment.

Mark Matney↗
NASA NTRS2014

SPHERES National Lab Facility

SPHERES is a facility of the ISS National Laboratory with three IVA nano-satellites designed and delivered by MIT to research estimation, control, and autonomy algorithms. Since Fall 2010, The SPHERES system is now operationally supported and managed by NASA Ames Research Center (ARC). A SPHERES Program Office was established and is located at NASA Ames Research Center. The SPHERES Program Office coordinates all SPHERES related research and STEM activities on-board the International Space Station (ISS), as well as, current and future payload development. By working aboard ISS under crew supervision, it provides a risk tolerant Test-bed Environment for Distributed Satellite Free-flying Control Algorithms. If anything goes wrong, reset and try again! NASA has made the capability available to other U.S. government agencies, schools, commercial companies and students to expand the pool of ideas for how to test and use these bowling ball-sized droids. For many of the researchers, SPHERES offers the only opportunity to do affordable on-orbit characterization of their technology in the microgravity environment. Future utilization of SPHERES as a facility will grow its capabilities as a platform for science, technology development, and education.

Free Flyer↗
NASA NTRSDate not supplied

Optical Characterization of DebriSat Fragments in Support of Orbital Debris Environmental Models

The NASA Orbital Debris Program Office (ODPO) develops, maintains, and updates orbital debris environmental models, such as the NASA Orbital Debris Engineering Model (ORDEM), to support satellite designers and operators by estimating the risk from orbital debris impacts on their vehicles in orbit. Updates to ORDEM utilize the most recent validated datasets from radar, optical, and in situ sources to provide estimates of the debris flux as a function of size, material density, impact speed, and direction along a mission orbit. On-going efforts within the NASA ODPO to update the next version of ORDEM include a new parameter that highly affects the damage risk – shape. Shape can be binned by material density and size to better understand the damage assessments on spacecraft. The in situ and laboratory research activities at the NASA ODPO are focused on cataloging and characterizing fragments from a laboratory hypervelocity-impact test using a high-fidelity, mock-up satellite, DebriSat, in controlled and instrumented laboratory conditions. DebriSat is representative of present-day, low Earth orbit satellites, having been constructed with modern spacecraft materials and techniques. The DebriSat fragment ensemble provides a variety of shapes, bulk densities, and dimensions. Fragments down to 2 mm in size are being characterized by their physical and derived properties. A subset of fragments is being analyzed further in NASA’s Optical Measurement Center (OMC) using broadband, bidirectional reflectance measurements to provide insight into the optical-based NASA Size Estimation Model. Additionally, pre-impact spectral measurements on a subset of DebriSat materials were acquired for baseline material characterization. This paper provides an overview of DebriSat, the status of the project, and ongoing fragment characterization efforts within the OMC.

Heather M Cowardin↗
NASA NTRS2021

Optical Characterization of DebriSat Fragments in Support of Orbital Debris Environmental Models

The NASA Orbital Debris Program Office (ODPO) develops, maintains, and updates orbital debris environmental models, such as the NASA Orbital Debris Engineering Model (ORDEM), to support satellite designers and operators by estimating the risk from orbital debris impacts on their vehicles in orbit. Updates to ORDEM utilize the most recent validated datasets from radar, optical, and in situ sources to provide estimates of the debris flux as a function of size, material density, impact speed, and direction along a mission orbit. On-going efforts within the NASA ODPO to update the next version of ORDEM include a new parameter that highly affects the damage risk – shape. Shape can be binned by material density and size to better understand the damage assessments on spacecraft. The in situ and laboratory research activities at the NASA ODPO are focused on cataloging and characterizing fragments from a laboratory hypervelocity-impact test using a high-fidelity, mock-up satellite, DebriSat, in controlled and instrumented laboratory conditions. DebriSat is representative of present-day, low Earth orbit satellites, having been constructed with modern spacecraft materials and techniques. The DebriSat fragment ensemble provides a variety of shapes, bulk densities, and dimensions. Fragments down to 2 mm in size are being characterized by their physical and derived properties. A subset of fragments is being analyzed further in NASA’s Optical Measurement Center (OMC) using broadband, bidirectional reflectance measurements to provide insight into the optical-based NASA Size Estimation Model. Additionally, pre-impact spectral measurements on a subset of DebriSat materials were acquired for baseline material characterization. This paper provides an overview of DebriSat, the status of the project, and ongoing fragment characterization efforts within the OMC.

Heather M. Cowardin↗
NASA NTRS1980

A solar encounter mission - Starprobe

Accurate measurements of the internal mass distribution and dynamics of the sun as well as in situ observations of its environs are proposed through a JPL-designed satellite, STARPROBE. Scheduled for launch in 1988 under NASA's five-year plan, the probe will conduct radiometric experiments to determine the solar quadrupole moment (J2), fields-and-particles experiments (evaluating such phenomena as heating, acceleration, and peak random velocity of solar wind), and optical experiments potentially superior to those of the Earth-orbiting Solar Optical Telescope (SOT). With flight times ranging from 2.7 to 5.9 years, present delivery options comprise planetary gravity-assist trajectories that will give the spacecraft a perihelion of four solar radii at a 90 deg-inclination. Owing to science- and mission requirements, the thermal shield of the craft should tolerate a solar flux 3000 times greater than that at earth, radioisotope thermoelectric generators supplying 700 watts of power, and a three-axis stabilization system with reaction wheels providing control torque. Implementation concepts now under study may change some of the details of the design.

Randolph, J. E.↗
NASA NTRS1960

Thermal Design of the Micrometeoroid Satellite S-55

The thermal design of the micrometeoroid satellite S-55 involves both experimental and analytical approaches in selecting materials and coatings. A cutaway drawing of the S-55 satellite is shown. The purpose of which is to obtain scientific and engineering design data on the frequency and penetration hazard of micrometeoroids at altitudes between about 250 nautical miles and 700 nautical miles. The passive method of thermal control used involves the selection of materials and coatings that give the desired ratio of absorptivity to emissivity alpha/epsilon for keeping the telemetry temperature within narrow limits and also to prevent overheating of the separate experiments. The selection of a material or coating for this purpose, however, is dictated not only by its absorptivity and emissivity values, but also by its reliability and the constancy of these values under long exposure to the space environment. Several test programs have been conducted in order to evaluate the materials and coatings being considered. Some of these are as follows: (1) Ultraviolet radiation in a vacuum to study discoloration and weight change. (2) Solar radiation in a vacuum to determine maximum equilibrium temperature, discoloration, and weight loss. (3) Thermal cycling and thermal shock to study material integrity (leaking, spalling, melting, etc.). (4) Proton radiation to observe effects on color, crystal structure, and strength. (5) Determination of effects of heat associated with coating application on the leak rate of pressurized parts. (6) Absorptivity and emissivity measurements. The experimental tests outlined and the maximum use of coating methods successfully employed on previous satellites should provide high reliability of the material used for the thermal design of this vehicle. A theoretical analysis was made to determine the values of alpha/epsilon required for different areas in order that the telemetry remain within the desired temperature limits.

Hastings, Earl C., Jr.↗
NASA NTRS1961

Nasa Plans Report: Addendum - Section 1

The ultimate aim of the NASA Program is to provide means of making astronomical observation in all wavelengths of the electromagnetic spectrum and in addition to launch satellites designed for experiments in geodesy and relativity. However, in the near future, emphasis is being placed primarily on long wavelength radio astronomy and, particularly, on astronomical photometry and spectroscopy in the portion of the spectrum to the violet of 3000 Angstrom. It is these regions which are most completely cut off from observations from the earth's surface and, in addition, it is in the far ultraviolet wavelength region that many astrophysically important lines are found.

Roman, Nancy G.↗
NASA NTRS1972

Space Satellite Dynamics with Applications to Sunlight Pressure Attitude Control

A research program into three aspects of space satellite dynamics was carried out. First, a four-dimensional space-time formulation of Newtonian mechanics is developed. This theory allows a new physical interpretation of the conservation theorems of mechanics first derived rigorously by Noether. Second, a new concept for estimating the three angles which specify the orientation in space of a rigid body is presented. Two separate methods for implementing this concept are discussed, one based on direction cosines, the other on quaternions. Two examples are discussed: constant orientation in space, and constant rate of change of the three angles with time. Third, two synchronous equatorial orbit communication satellite designs which use sunlight pressure to control their attitude are analyzed. Each design is equipped with large reflecting surfaces, called solar sails, which can be canted in different directions to generate torques to correct pointing errors.

Stuck, B. W.↗
NASA NTRS1974

Orbital operation for large automated satellites

Orbital operations concepts for the shuttle launched Large Automated Satellites (LAS) are discussed. It includes the orbital operations elements and the major options for accomplishing each element. This study is based on the preliminary payload information available in Level I and II documents and on orbital operations methods used on past programs, both manned and unmanned. It includes a definition of detailed trade studies which need to be performed as satellite design details and organization responsibilities are defined. The major objectives of this study were to define operational methods and requirements for the long duration LAS missions which are effective and primarily economical to implement.

Lusk, J. L.↗
NASA NTRS1974

OSO-7 observations of a high-latitude X-ray source associated with Abell cluster A2052

An X-ray source with a flux of 1.6 times 10 to the -10th power ergs per sec/sq cm (2-10 keV) has been observed at high galactic latitude by the MIT X-ray detectors on the OSO-7 satellite. Designated GX 8+50, its position is 15 hr 14.2 min right ascension, 6 deg 51 min declination, with a 90 percent confidence error circle of area 0.5 sq deg. The data are consistent with a power-law spectrum with an exponent 1.2 (plus or minus 0.2) or a thermal-bremsstrahlung spectrum with kT = 4 plus or minus 1 keV. A likely identification is the Abell cluster A2052, whose center coincides with the radio source 3C 317.

Heinz, C. J.↗