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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

A numerical model of electrodynamics of plasma within the contaminant gas cloud of the Space Shuttle Orbiter at low earth orbit

A two-dimensional cloud was used to study the plasma dynamics within the outgas cloud associated with the Orbiter. It is shown that the polarization field is not symmetric about the direction of motion of the outgas cloud. It rotates in a way that can be predicted in simple cases by the ratio of the Hall and Pederson currents within the outgas cloud. The polarization field magnitude produced in the model was not large.

Eccles, J. Vincent↗
NASA NTRS1992

TOPEX orbit determination and gravity recovery using Global Positioning System data from repeat orbits

A covariance analysis is presented for satellite tracking and gravity recovery with a differential Global Positioning System-based technique to be demonstrated on TOPEX in the early 1990s. The technique employs data from an ensemble of repeat ground tracks to recover a unique satellite epoch state for each track and a set of invariant positional parameters common to all tracks. The positional parameters represent the effect of mismodeled gravitational field on the satellite orbit. At an altitude of 1336 km, where gravity modeling is the dominant systematic error, averaging of random error over many arcs and adjustment of the gravity model reduce the final satellite position error. The positional parameters can then be used to produce a refined global gravity model. The analysis indicates that errors ranging from 5 to 8 cm in TOPEX altitude and 0.05 to 0.2 mGal for the gravity field can be achieved, depending on the number of repeat arcs used.

Wu, Jiun-Tsong↗
NASA NTRS1992

Space Shuttle Orbiter Fleet Leader Orbital Maneuvering Engine SN 002A injector replacement

During testing of the Fleet Leader Orbital Maneuvering Engine (OME) Serial Number (SN) 002A at the White Sands Test Facility (WSTF) in 1983 the injector was inadvertently damaged. After testing was completed in 1985, there was a concern that the performance of the engine and its response to specific test conditions might not be sufficiently representative of flight engines to provide valid test results. To correct this damage, the engine was returned to the manufacturer to replace the injector. The task assigned was to evaluate the damage and generate a unique process to repair the Fleet Leader OME while providing minimum impact to the overall life condition of the engine. In addition to successfully performing the repair operation, the as received condition of the engine and its components were documented for Fleet Leader reference. The engine is currently at WSTF where it has accumulated 11,341 seconds of firing time to date, 2615 seconds of which have occurred since the engine repair.

Riccio, Joseph R.↗
NASA NTRS1992

Methodology for the passive control of orbital inclination and mean local time to meet sun-synchronous orbit requirements

The mean local time (MLT) of equatorial crossing of a sun-synchronous Earth-observing spacecraft orbit drifts with inclination; therefore, in order to maintain the MLT, the inclination must be controlled. Inclination may be maintained actively by costly out-of-plane maneuvers or passively by using the perturbing forces due to the sun and moon. This paper examines the passive control approach using the Earth Observing System (EOS) as a basis for the discussion. Applications to Landsat and National Oceanic and Atmospheric Administration (NOAA) spacecraft are presented for comparison. This technique is especially beneficial to spacecraft lacking propulsion systems. The results indicate that passive inclination control appears to be the preferable maintenance method when spacecraft weight restrictions, operational considerations, and scientific requirements apply.

Folta, David↗
NASA NTRS1993

A simultaneous estimation of the mass of Mars and its natural satellites, Phobos and Deimos, from the orbital perturbations on the Mariner 9, Viking 1, and Viking 2 orbiters

The natural satellites of Mars, Phobos and Deimos, caused perturbations on the orbits of the Mariner 9, and the Viking spacecraft that were used to estimate the satellite masses. The Viking spacecraft were specifically targeted to make close flybys (within a few hundred kilometers) of Phobos in February 1977 and of Deimos in October 1977. These close encounters were used to estimate the moon's gravitational constant, GM (the universal constant of gravitation multiplied by the satellite mass). However, the Viking and Mariner 9 spacecraft made numerous flybys of Phobos and Deimos at distances of a few thousand kilometers. The tracking data from these more 'distant' encounters were processed to estimate the masses of Mars, Phobos, and Deimos.

Lemoine, F. G.↗
NASA NTRS2008

International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Erickson, Robert J.↗
NASA NTRS2016

Degradation of Beta Cloth Covering for a Battery Orbital Replacement Unit in Low Earth Orbit

Samples from the beta cloth cover for a battery orbit replaceable unit from the International Space Station (ISS) were characterized using optical and electron microscopy, UV-vis-NIR spectrophotometry, and x-ray energy dispersive spectroscopy. Results showed that in areas where the fabric was exposed to solar radiation the absorptance increased by as much as 20 percent, and the peak difference was in the ultraviolet, indicating that the increased absorptance may have been due to radiation. The emissivity of the material over a temperature range of 300 to 700 K was essentially unchanged.

Solar Physics↗
NASA NTRS2016

Degradation of Beta-Cloth Covering for a Battery Orbital Replacement Unit in Low Earth Orbit

Samples from the B-cloth cover for a battery orbit replaceable unit from the International Space Station were characterized using optical and electron microscopy, UV-vis-NIR spectrophotometry, and x-ray energy dispersive spectroscopy. Results showed that in areas where the fabric was exposed to solar radiation the absorptance increased by as much as 20 percent, and the peak difference was in the ultraviolet, indicating that the increased absorptance may have been due to radiation. The emissivity of the material over a temperature range of 300 - 700 K was essentially unchanged.

Solar Physics↗
NASA NTRS2019

Attitude Control and Orbit Determination of a Crewed Spacecraft with Lunar Lander in near Rectilinear Halo Orbit

NASA's Gateway program plans to place a crew-tended spacecraft in cislunar Near Rectilinear Halo Orbit (NRHO). The craft will support arrivals of crews in Orion and the undocking and return of a crewed lunar lander. The impact to at-titude control of a Gateway with the addition of a lunar lander is investigated. Perturbations from Orion and a lander's docking and undocking from the Gate-way are considered. Deep Space Network (DSN) tracking is supplemented with optical measurements to lunar north pole craters to analyze the possible benefit in solution accuracy and/or DSN scheduling relief.

Newman, Clark P.↗
NASA NTRS2007

Mars Reconnaissance Orbiter Mission: Systems Engineering Challenges on the Mars Reconnaissance Orbiter Mission

MRO project is a system of systems requiring system engineering team to architect, design, integrate, test, and operate these systems at each level of the project. The challenge of system engineering mission objectives into a single mission architecture that can be integrated tested, launched, and operated. Systems engineering must translate high-level requirements into integrated mission design. Systems engineering challenges were overcome utilizing a combination by creative designs built into MRO's flight and ground systems: a) Design of sophisticated spacecraft targeting and data management capabilities b) Establishment of a strong operations team organization; c) Implementation of robust operational processes; and d) Development of strategic ground tools. The MRO system has met the challenge of its driving requirements: a) MRO began its two-year primary science phase on November 7, 2006, and by July 2007, met it minimum requirement to collect 15 Tbits of data after only eight months of operations. Currently we have collected 22 Tbits. b) Based on current performance, mission data return could return 70 Tbits of data by the end of the primary science phase in 2008.

systems engineering↗