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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
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

An overview of the evolution of Landsat-4

Landsat-4 was launched on July 16, 1982, from Vandenberg Air Force Base in California. This launch culminated over a decade of planning, design, and implementation effort. During this period, many decisions and choices had to be made involving such items as the characteristics of the second-generation observing instrument named the Thematic Mapper (TM), the orbital altitude and coverage pattern, the configuration of the ground processing systems, etc. In total, the design and operation of Landsat-4 depart substantially from those of the successful Landsat 1, 2, and 3 series. Results derived from the operation of Landsat-4 systems and analyses of data products indicate that there have been very significant successes associated with Landsat-4. The TM provides observations that are considerably improved over the Multispectral Scanner (MSS). The middle-infrared bands at 1.6 and 2.2 micrometers, for example, are providing land-cover classification results that meet or exceed expectations. It is now hoped that successful operation of Landsat-4, Landsat-D' (D-prime), and the Tracking and Data Relay Satellite System (TDRSS) will permit the acquisition of a worldwide set of TM and MSS observations.

Salomonson, V. V.↗
NASA NTRS1984

Landsat-4 sensor performance

Preflight and in-orbit sensor and data measurements indicate that TM meets or exceeds most specifications. Measured spectral band edges meet instrument specifications in 12 out of 14 cases; there is ample dynamic range. The signal-to-noise ratio exceeds specifications, except for band 3, channel 4; and band 7 channel 7 is very noisy but still meets specifications. The modulation transfer function of channel 4, band 2, is smaller than specified. Registration errors between the primary focal plane (PFP) and the cold focal plane (CFP) are about 0.75 pixels along-scan and 0.2 pixels across scan. Forward and reverse scan discontinuities are well within ground-processing capabilities to rectify. Instrument gain variability, up to 7 percent for band 5, requires use of the internal calibration (IC) system to assure radiometric accuracy. Preliminary applications evaluation of image contents indicates that TM provides much better definition of edges than MSS.

Barker, J. L.↗
NASA NTRS1985

Payload transportation at KSC

Cargo ground processing at John F. Kennedy Space Center (KSC) involves either a horizointal or vertical mode of assembly and processing of the STS payloads. Consequently, cargos are commonly referred to as horizontal or vertical payloads. The process flow for each mode requires different facilities and transportation requirements. Occasionally, a mixed mission cargo containing both horizontal and vertical payload elements will require a combination of horizontal and vertical transportation between facilities. Some of the engineering challenges and innovative solutions to satisy the unique on-site payload transportation requirements at KSC. In particular, some of the more demanding design requirements of the multiuse mission support equipment are presented, and the resulting engineering designs and unique solutions are outlined.

Donahue, M. E.↗
NASA NTRS1985

An Analysis of the High Frequency Vibrations in Early Thematic Mapper Scenes

The motion of the mirrors in the thematic mapper (TM) and multispectral scanner (MSS) instruments, and the motion of other devices, such as the TDRSS antenna drive, and solar array drives onboard LANDSAT-4 cause vibrations to propagate through the spacecraft. These vibrations as well as nonlinearities in the scanning motion of the TM mirror can cause the TM detectors to point away from their nominal positions. Two computer programs, JITTER and SCDFT, were developed as part of the LANDSAT-D Assessment System (LAS), Products and Procedures Analysis (PAPA) program to evaluate the potential effect of high frequency vibrations on the final TM image. The maximum overlap and underlap which were observed for early TM scenes are well within specifications for the ground processing system. The cross scan and scan high frequency vibrations are also within the specifications cited for the flight system.

Kogut, J.↗
NASA NTRS1985

Thematic Mapper Data Quality and Performance Assessment in Renewable Resources/agriculture/remote Sensing

Analysis of the early thematic mapper (TM) data indicate the TM sensor and associated ground processing are performing equal to the high expectations and within advertised specifications. The overall TM system with improved resolution, together with additional and more optimumly placed spectral bands shows much promise for benefits in future analysis activities. By selecting man-made features of known dimensions (e.g., highways, airfields, buildings, and isolated water bodies), an assessment was made of the TM performance relative to the specified 30-meter (98-foot) resolution. The increase of spatial resolution of TM (30 m) over MSS (80 M) appears to be significant not only in resolving spectrally distinct classes that were previously undefinable but also in distinguishing within-field variability. An Important result of the early TM evaluation and pre-TM analyses was the development of an integrated system to receive LANDSAT-4 TM (as well as MSS) data and analyze the data via various approaches.

Bizzell, R. M.↗
NASA NTRS1985

Some experiences with botanical experiments in the orbiter middeck

The use of the Plant Growth Unit for botanical flight experiments on the STS-3 and 51-F flights is described. Inadequate temperature control on the STS-3 flight required a modification which eliminated the cooler night cycle on the 51-F flight. In-flight photography was added to the 51-F flight procedures because the postflight recovery period was sufficiently long to produce a gravity-induced bending in some plants. Ground processing at Dryden Flight Center was accomplished but improvements in the facilities available would be desirable.

Merek, E. L.↗
NASA NTRS1984

Spacelab Mission Implementation Cost Assessment (SMICA)

A total savings of approximately 20 percent is attainable if: (1) mission management and ground processing schedules are compressed; (2) the equipping, staffing, and operating of the Payload Operations Control Center is revised, and (3) methods of working with experiment developers are changed. The development of a new mission implementation technique, which includes mission definition, experiment development, and mission integration/operations, is examined. The Payload Operations Control Center is to relocate and utilize new computer equipment to produce cost savings. Methods of reducing costs by minimizing the Spacelab and payload processing time during pre- and post-mission operation at KSC are analyzed. The changes required to reduce costs in the analytical integration process are studied. The influence of time, requirements accountability, and risk on costs is discussed. Recommendation for cost reductions developed by the Spacelab Mission Implementation Cost Assessment study are listed.

Guynes, B. V.↗
NASA NTRS1986

Rarefied flow lift-to-drag measurements of the Shuttle Orbiter

This report presents a discussion of the analysis and the results of sensitive micro-g accelerometry measurements on the Shuttle Orbiter in the rarefied flow flight regime, that is, from altitudes of 60 km to 160 km. A brief description of the experimental apparatus called High Resolution Accelerometer Package (HiRAP) is given along with a description of the ground processing to obtain the lift-to-drag ratio (L/D) from the flight measurements. The flight results of L/D from six missions are presented and discussed. Comparisons are made with preflight wind tunnel data in the near continuum viscous interaction regime and preflight analytical estimates in the rarefied transition regime. Excellent agreement is obtained between flight and wind tunnel data in the viscous regime, but differences are noted between flight and preflight predictions in the transition regime. Free molecule flow F/D data are also obtained on each mission. Comparisons of flight data with classical theory show that complete diffuse reflection is not an appropriate model for rarefied aerodynamic coefficient calculations, and, for the Shuttle, some specular fraction is required. Surface reflection laws are explored to define the sensitivity of the L/D measurements to gas-surface molecule interactions.

Blanchard, R. C.↗
NASA NTRS1986

Radiometric calibration of the Shuttle Imaging Radar (SIR-C) system

The radiometric calibration accuracy of the Shuttle Imaging Radar (SIR-C) sensor is discussed. The analysis includes the antenna, RF electronics, the digital data handling system, the platform attitude control, attitude determination accuracy, and orbit effects. The radiometric distortion of the image products by the ground processing system used for the image formation is also considered. Since the SIR-C system is a dual-frequency quad-polarized system (i.e., 8 channels), the amplitude and phase error is considered over all possible operating modes and environments for absolute and relative (long-term and short-term) calibration within a channel and across channels.

Curlander, John C.↗
NASA NTRS1987

Development of the helium signature test for orbiter main propulsion system revalidation between flights

This paper presents the development of a test technique for revalidation of the Space Shuttle Orbiter Main Propulsion System during ground turnaround operations between flights of the Space Transportation System (STS). The Main Propulsion System consists of the three Space Shuttle Main Engines (SSME's) and the Main Propulsion System (MPS) connecting the SSME's to the orbiter/ground and orbiter/External Tank (ET) interfaces. The Helium Signature Test (HST) performs an end-to-end leak check of the MPS/SSME subsystems that serves as a final validation of those systems for reuse. The test was initially developed during the ground processing flow prior to the STS-6 launch of orbiter Challenger. The test was developed to fulfill a requirement for an overall subsystem leak check as a result of experience gained during the STS-6 Challenger Flight Readiness Firing (FRF) series, during which leaks were encountered in the SSME's that were not detected by routine fluid joint leak checks. The HST technique is described in detail, including orbiter and test equipment configuration, and compared to other leak detection methods used to revalidate MPS/SSME systems for reuse. The HST data base accumulated since STS-6 is summarized and future test applications are described.

Bilardo, Vincent J., Jr.↗
NASA NTRS1986

Contamination control of the space shuttle Orbiter crew compartment

Effective contamination control as applied to manned space flight environments is a discipline characterized and controlled by many parameters. An introduction is given to issues involving Orbiter crew compartment contamination control. An effective ground processing contamination control program is an essential building block to a successful shuttle mission. Personnel are required to don cleanroom-grade clothing ensembles before entering the crew compartment and follow cleanroom rules and regulations. Prior to crew compartment entry, materials and equipment must be checked by an orbiter integrity clerk stationed outside the white-room entrance for compliance to program requirements. Analysis and source identification of crew compartment debris studies have been going on for two years. The objective of these studies is to determine and identify particulate generating materials and activities in the crew compartment. Results show a wide spectrum of many different types of materials. When source identification is made, corrective action is implemented to minimize or curtail further contaminate generation.

Bartelson, Donald W.↗
NASA NTRS1988

NASA's post-Challenger safety program - Themes and thrusts

The range of managerial, technical, and procedural initiatives implemented by NASA's post-Challenger safety program is reviewed. The recommendations made by the Rogers Commission, the NASA post-Challenger review of Shuttle design, the Congressional investigation of the accident, the National Research Council, the Aerospace Safety Advisory Panel, and NASA internal advisory panels and studies are summarized. NASA safety initiatives regarding improved organizational accountability for safety, upgraded analytical techniques and methodologies for risk assessment and management, procedural initiatives in problem reporting and corrective-action tracking, ground processing, maintenance documentation, and improved technologies are discussed. Safety issues relevant to the planned Space Station are examined.

Rodney, G. A.↗
NASA NTRS1987

SAR image data compression for an on-line archive system

This paper summarizes the investigation of SAR image data compression for an on-line archive data distribution system. This system is planned for the ground processing system of Alaska SAR Facility (ASF) and Shuttle Imaging Radar (SIR-C). The objective of the SAR image data compression is to enable the data archive system to provide the remote users a large data base with good image quality, short response time, low transfer cost, and minimal decoding complexity. The requirements and limitations of the on-line archive data distribution system are presented. The effects of SAR image data characteristics on data compression are addressed. The users' survey results suggest that compression ratios between 10:1 and 20:1 appear suitable. Based on the algorithm evaluation results, the two-level tree-searched vector quantization technique has been recommended as the SAR image data compression algorithm for the on-line archive data distribution system.

Chang, C. Y.↗
NASA NTRS1988

GPS-based precision orbit determination - A Topex flight experiment

Plans for a Topex/Poseiden flight experiment to test the accuracy of using GPS data for precision orbit determination of earth satellites are presented. It is expected that the GPS-based precision orbit determination will provide subdecimeter accuracies in the radial component of the Topex orbit when the extant gravity model is tuned for wavelengths longer than about 1000 kms. The concept, design, flight receiver, antenna system, ground processing, and data processing of GPS are examined. Also, an accurate quasi-geometric orbit determination approach called nondynamic or reduced dynamic tracking which relies on the use of the pseudorange and the carrier phase measurements to reduce orbit errors arising from mismodeled dynamics is discussed.

Melbourne, William G.↗
NASA NTRS1989

On-board data analysis techniques for space plasma particle instruments

This article describes the on-board data analysis techniques used on two recent space plasma particle instruments to compute meaningful parameters of three-dimensional plasma distributions in real time. These parameters may be transmitted with much higher time resolution than the full distribution within the limited telemetry. In addition, they greatly reduce the ground processing requirements.

Curtis, D. W.↗
NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the landing/deceleration subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Landing/Deceleration Subsystem hardware. The Landing/Deceleration Subsystem is utilized to allow the Orbiter to perform a safe landing, allowing for landing-gear deploy activities, steering and braking control throughout the landing rollout to wheel-stop, and to allow for ground-handling capability during the ground-processing phase of the flight cycle. Specifically, the Landing/Deceleration hardware consists of the following components: Nose Landing Gear (NLG); Main Landing Gear (MLG); Brake and Antiskid (B and AS) Electrical Power Distribution and Controls (EPD and C); Nose Wheel Steering (NWS); and Hydraulics Actuators. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Due to the lack of redundancy in the Landing/Deceleration Subsystems there is a high number of critical items.

Compton, J. M.↗
NASA NTRS1991

Development of a relatchable cover mechanism for a cryogenic IR-sensor

A cover mechanism for use on the Infrared Background Signature Survey (IBSS) cryostat was developed. The IBSS IR-instrument is scheduled for STS launch in early 1991 as a payload of the Shuttle Payload Satellite (SPS) 2. The cover is hinged, with a motorized rope drive. During ground processing, launch, entry, and landing, the cryostat, which houses the IR-instrument, is required to be a sealed vacuum tight container for cooling purposes and contamination prevention. When on orbit, the cover is opened to provide an unobstructed field of view for the IR-instrument. A positive seal is accomplished through the use of latch mechanism. The cover and the latch are driven by a common redundant actuator consisting of dc motors, spur gears, and a differential gear. Hall probe limit switches and position sensors (rotary variable transformer) are used to determine the position of the cover and the latch. The cover mechanism was successfully qualified for thermal vacuum (-25 to 35 C), acoustic noise, vibration (6 Gs sine, 9.7 G RMS) and life cycles. Constricting requirements, mechanical and electronic control design, specific design details, test results of functional performance, and environmental and life tests are described.

Birner, R.↗
NASA NTRS1991

Retrievable Payload Carrier (RPC): Next generation Long Duration Exposure Facility

The Retrievable Payload Carrier (RPC) is described which is a multi-experiment, free-flyer spacecraft being privately developed to make in-space experimentation more accessible and economically feasible for research and development organizations. The carrier concept was derived from NASA's highly successful and flight proven Long Duration Exposure Facility (LDEF). The LDEF capabilities were enhanced to meet new customer requirements. This reusable payload carrier is planned for launch and retrieval by the space shuttle on a regular basis. The RPC's compact design facilitates flexible manifesting of the shuttle cargo bay space, thereby, permitting timely launches and retrievals. The vehicle is designed so that either the entire carrier can be retrieved from orbit, or individual experiment pallets can be removed and replaced in orbit. This gives customers even greater control over their experiment recoveries. A fully operational RPC System consists of: (1) a carrier spacecraft; (2) a ground control station for communication with customer payloads and the carrier; (3) a ground processing facility to provide refurbishment, final checkout, and integration of customer payloads and the carrier; and (4) the personnel required to support both the development and operation phases of the program. Customer payloads will fly 6 to 18 month missions, or longer, as required. Spreading launch, operations, and retrieval costs over multiple experimental payloads results in minimized customer costs. The RPC Program's initial objective is to operate a simple carrier system which meets basic customer service needs.

Perry, Arthur T.↗