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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 361 records · Page 20

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NASA NTRS1981

Solar hot water system installed at Las Vegas, Nevada

A solar energy hot water system installed in a motor inn at Las Vegas, Nevada is described. The inn is a three story building with a flat roof for installation of the solar panels. The system consists of 1,200 square feet of liquid flat plate collectors, a 2,500 gallon insulated vertical steel storage tank, two heat exchangers, and pumps and controls. The system was designed to supply approximately 74 percent of the total hot water load.

Source record↗

NASA NTRS1981

A BAPTA employing rotary transformers, stepper motors and ceramic ball bearings

The utilization of rotary transformers as an alternative to slip rings for the power transfer from solar panels to a satellite's main body could be advantageous, especially if an ac bus system is taken into consideration. Different approaches with main emphasis on the electromagnetic design were investigated and showed efficiencies of up to 99% with a 3 kW power capability. A solidly preloaded pair of ball bearings with ceramic balls assures proper transformer air gaps and acceptable torque changes over temperature and temperature gradients. The bearing and power transfer assembly is driven by a direct drive stepper motor with inherent redundancy properties and needs no caging mechanism.

Auer, W.↗

NASA NTRS1980

Anti-reflection coatings applied by acid leaching process

The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

Pastirik, E.↗

NASA NTRS1980

Space fabrication - The key to future large space systems

Construction techniques for large space structures are discussed. It is pointed out that in contrast to assembly in orbit and the deployment technique space fabrication offers favorable densities (transporting structural materials on reels) and can be adapted to automated construction. A space fabrication machine containing reels of flat sheet material and sets of rollers or dies is described, as is a machine for fabricating composite material (which must be heated for forming and then cooled to achieve structural strength). The use of fabrication machines to build such structures as space platforms, microwave radiometers, and satellite power systems is discussed. The versatility of the machine when operated in conjunction with the Space Shuttle and a set of jigs is illustrated by showing how large square solar panels and large hexagonal structures could be constructed. The need for a flight demonstration of the fabrication machine is stressed.

Savage, M.↗

NASA NTRS1981

The NASA Tracking and Data Relay Satellite System and its impact on spacecraft support in the space transportation system era

The space tracking, data acquisition and communication network systems and capabilities available to NASA are discussed, with emphasis on the Tracking and Data Relay Satellite System (TDRSS). Scheduled to come into operation in 1983, TDRSS will be the prime support system for communication with the Space Shuttle, Spacelab, and the automated spacecraft to be launched into earth orbit by the Space Transportation System. TDRSS will consist of two specialized data relay satellites in geosynchronous orbit, about 130 deg apart; each TDRSS spacecraft has a three-axis stabilized configuration, with sun-oriented solar panels, and will weigh about 2200 kg at launch. The NASA Spaceflight Tracking and Data Network, currently used to support 30-40 spacecraft per day, is described, and plans for changes in the network are discussed. The 26 antennas of the network will be consolidated into an expanded Deep Space Network, after TDRSS is in operation.

Smylie, R. E.↗

NASA NTRS1982

Control system design for the large space systems technology reference platform

Structural models and classical frequency domain control system designs were developed for the large space systems technology (LSST) reference platform which consists of a central bus structure, solar panels, and platform arms on which a variety of experiments may be mounted. It is shown that operation of multiple independently articulated payloads on a single platform presents major problems when subarc second pointing stability is required. Experiment compatibility will be an important operational consideration for systems of this type.

Edmunds, R. S.↗

NASA NTRS1982

Solar drum positioner mechanisms

The need for additional power on spinning satellites required development of deployable solar arrays activated, as on a 3-axis vehicle, after separation from a booster or shuttle orbiter. Mechanisms were developed for telescopically extending a secondary 36.3 kg (80 lb.), 2.13 m (84 in.) diameter spinning solar drum for a distance of 2.0 m (80 in.) or more along the spin axis. After extension, the system has the capability of dynamically controlling the drum tilt angle about the spin axis to provide precision in-orbit balancing of the spacecraft. This approach was selected for the SBS, ANIK C, ANIK D, WESTAR B and PALAPA B satellites. It was successfully demonstrated during the in orbit deployment of the aft solar panels of the SBS F-3 and F-1 satellites, subsequent to the November 1980 and September 1981 launches.

Briggs, L. W.↗

NASA NTRS1981

Technology requirements for GaAs photovoltaic arrays

An analysis based on percent GaAs solar cell weight and cost is performed to assess the utility of this cell for future space missions. It is shown that the GaAs substrate cost and the end-of-life (EOL) advantage the cell can provide over the space qualified silicon solar cell are the dominant factors determining potential use. Examples are presented to show that system level advantages resulting from reduction in solar panel area may warrant the use of GaAs at its current weight and projected initial cost provided the EOL advantage over silicon is at least 20 percent.

Scott-Monck, J.↗

NASA NTRS1983

Hiding Solar-Array Bus Bars

End terminals mounted under cells, maximizing usable illuminated area. Reconfigured solar panel bus bars placed under cells, reducing portion of module area not occupied by active silicon. Underside of last cell in string of cells serves as contact for positive bus. Negative tab of last cell in string is wrapped around from top of cell. Tabs are connected to output boards mounted under cells.

Hufnagel, W. F.↗

NASA NTRS1982

Method for depositing an oxide coating

A metal oxide coating is plated onto a metal substrate at the cathode from an acid solution which contains an oxidizing agent. The process is particularly useful for producing solar panels. Conventional plating at the cathode avoids the presence of oxidizing agents. Coatings made in accordance with the invention are stable both at high temperatures and while under the influence of high photon flux in the visible range.

Mcdonald, G. E.↗

NASA NTRS1983

Multimission advanced configuration

The proposed multimission configuration reduces the number of reflectors present on the spacecraft and their related supporting structure (masts, booms) and at the same time divides the feed system from the reflector system for possible maintenance and/or payload substitution. This implies: An antenna system that is split into two parts: (1) the reflector with the platform (2) the feed subsystem with the payload. Reuse of the same reflector at different frequencies (to achieve this, the reflector system will use additional components, i.e., frequency sensitive subreflectors (FSS)). In case of in-orbit refurbishment or maintenance, the reflector system may remain in orbit with the platform. The presence of the FSS allows separation of the focal position sufficiently for the multiple-contoured beam applications required by future missions. There are two of these reflectors (one for TX function, one for RV deployed) on the east and west sides of the spacecraft, and the solar panels are on the north and south sides. The payloads are aligned along the yaw axis. Apart from the size, this configuration looks like a conventional spacecraft.

Saitto, A.↗

NASA NTRS1982

Characterization of the outgassing of spacecraft materials

Equations which describe material outgassing in spaceflight conditions are integrated over temperatures up to 125 C and with outgassing kinetic energies up to 40 kcal/mole. The outgassing rate is noted to be formulated as an expression of sublimation and evaporation, and can be a function of the materials of the outgassing process. The predicted mass loss rates for various materials are compared with mass loss rates from materials with known activation energies, e.g., silicone and solar panel samples, held at different temperatures and for varying time lengths. The comparisons are made for first order and more complex outgassing kinetics. The technique is concluded to be useful for a quick characterization of candidate materials for spaceflight considerations when contamination is a significant factor.

Scialdone, J. J.↗

NASA NTRS1983

Airborne reconnaissance in the civilian sector - Agricultural monitoring from high-altitude powered platforms

Design concepts and mission applications for unmanned high-altitude powered platforms (HAPPs) are discussed. A chemically powered HAPP (operating altitude 18-21 km, wingspan 26 m, payload 91 kg, endurance 2-3 days) would use current turboprop technology. A microwave-powered HAPP (operating altitude around 21 km, wingspan 57.9 m, payload 500 kg, endurance weeks or months) would circle within or perform boost-glide maneuvers around a microwave beam of density 1.1 kw/sq m. Of two solar-powered-HAPP designs presented, the more promising uses five vertical solar-panel-bearing fins, two of which can be made horizontal at night, (wingspan 57.8/98.3 m, payload 113 kg, endurance weeks or months). The operating altitude depends on the latitude and season: this HAPP design is shown to be capable of year-round 20-km-altitude flights over the San Joaquin Valley in California, where an agricultural-monitoring mission using Landsat-like remote sensors is proposed. Other applications may be better served by the characteristics of the other HAPPs. The primary advantage of HAPPs over satellites is found to be their ability to provide rapidly available high-resolution continuous or repetitive coverage of specific areas at relatively low cost.

Youngblood, J. W.↗

NASA NTRS1983

Exosat/Delta - Demonstrated short-term backup launcher capability through international cooperation

The instrumentation, performance parameters, Delta launch implementation, and development program of the Exosat, launched in February 1983 are described. The X ray satellite was integrated into the Delta vehicle over a three month period, and will survey mainly previously observed X ray objects by directing its detectors at them just before they are occulted by the moon. The 120 kg science package, powered by 260 W of power from solar panels, include low- and medium-energy imaging devices. The spacecraft was originally intended for Ariane launch, but scheduling conflicts, plus the need for a polar-type orbit, dictated the use of the Western Space and Missile Center. Maintenance of Delta compatibility throughout the development of the Exosat facilitated the transfer of launch vehicles, as did full existing documentation of the spacecraft and familiarity between the ESA and NASA managers of the development and launch programs, respectively.

Ganoung, J. K.↗

NASA NTRS1984

Management and Performance of APPLE Battery in High Temperature Environment

India's first experimental communication satellite, APPLE, carried a 12 AH Ni-Cd battery for supplying power during eclipse. Failure to deploy one of the two solar panels resulted in the battery operating in a high temperature environment, around 40 C. This also resulted in the battery being used in diurnal cycles rather than just half yearly eclipse seasons. The management and performance of the battery during its life of two years are described. An attempt to identify the probable degradation mechanisms is also made.

Suresh, M. S.↗

NASA NTRS1982

Welded solar cell interconnection

The efficiency of the welding of solar-cell interconnects is compared with the efficiency of soldering such interconnects, and the cases in which welding may be superior are examined. Emphasis is placed on ultrasonic welding; attention is given to the solar-cell welding machine, the application of the welding process to different solar-cell configurations, producibility, and long-life performance of welded interconnects. Much of the present work has been directed toward providing increased confidence in the reliability of welding using conditions approximating those that would occur with large-scale array production. It is concluded that there is as yet insufficient data to determine which of three methods (soldering, parallel gap welding, and ultrasonic welding) provides the longest-duration solar panel life.

Stofel, E. J.↗

NASA NTRS1984

Comet rendezvous

A Mariner Mark II spacecraft rendezvous mission with comet Kopff has been recommended by NASA's Solar System Exploration Committee, and is scheduled for a Shuttle launch in 1990. The spacecraft, which is scheduled to encounter the comet in 1994, will conduct a series of experiments including the study of the cometary nucleus, coma, and tail during perihelion passage; the determination of the nucleus and coma chemical/isotropic composition; the description of the nucleus's size, mass, rotation period, and pole occultation; distinctions of gas and dust hydrodynamics; and distinctions of solar wind interactions with the coma. The three-axis-stabilized spacecraft will be modular in design, and will incorporate a 490-Newton Insat engine, Viking Orbiter propulsion tanks, an Integrated Platform Pointing and Attitude Control Subsystem, and several scientific instruments. The spacecraft's Radio Frequency Subsystem will only use X-band telemetry with a downlink frequency of 8415 MHz, and an uplink frequency of 7161 MHz. The power sources in the present design include one radioisotope thermoelectric generator, three 3 Ah batteries, and a solar panel of approximately 7 sq m.

Draper, R. F.↗

NASA NTRS1984

Autonomous momentum management for space station

Momentum management for the CDG planar space platform is discussed. It is assumed that the external torques on the space station are gravity gradient and aerodynamic, both have bias and cyclic terms. The integrals of the cyclic torques are the cyclic momenti which will be stored in the momentum storage actuator. Techniques to counteract the bias torques and center the cyclic momentum and gravity gradient desaturation by adjusting vehicle attitude, aerodynamic desaturation using solar panels and radiators and the deployment of flat plates at the end of long booms generating aerodynamic torques are investigated.

Hahn, E.↗