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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 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Discussion meeting on Gossamer spacecraft (ultralightweight spacecraft)

Concepts, technology, and application of ultralightweight structures in space are examined. Gossamer spacecraft represented a generic class of space vehicles or structures characterized by a low mass per unit area (approximately 50g/m2). Gossamer concepts include the solar sail, the space tether, and various two and three dimensional large lightweight structures that were deployed or assembled in space. The Gossamer Spacecraft had a high potential for use as a transportation device (solar sail), as a science instrument (reflecting or occulting antenna), or as a large structural component for an enclosure, manned platform, or other human habitats. Inflatable structures were one possible building element for large ultralightweight structures in space.

Brereton, R. G.↗
NASA NTRS1979

Interactions between a spacecraft and an ion thruster produced environment

A model of the charge-exchange plasma flow around a spacecraft is used to determine charge-exchange plasma densities and arrival rates at various locations on the spacecraft. A general assessment of particle deposition and effects of such are presented as they relate to the spacecraft and particular science instruments. Various aspects of the interactions between the ion thruster produced environment and a Comet Rendezvous (CR) spacecraft are addressed. No instruments will be affected adversely when the thrusters are off, excluding those that have passive radiators which may collect mercury.

Carruth, M. R., Jr.↗
NASA NTRS1980

Eight microprocessor-based instrument data systems in the Galileo Orbiter spacecraft

Instrument data systems consist of a microprocessor, 3K bytes of Read Only Memory and 3K bytes of Random Access Memory. It interfaces with the spacecraft data bus through an isolated user interface with a direct memory access bus adaptor, and/or parallel data from instrument devices such as registers, buffers, analog to digital converters, multiplexers, and solid state sensors. These data systems support the spacecraft hardware and software communication protocol, decode and process instrument commands, generate continuous instrument operating modes, control the instrument mechanisms, acquire, process, format, and output instrument science data.

Barry, R. C.↗
NASA NTRS1981

Experimental and analytical evaluation of ion thruster/spacecraft interactions

Studies were conducted to both identify the environment produced by ion thrusters and to assess the interaction of this environment on a typical spacecraft and typical science instruments. Spacecraft charging and the charge exchange that accompanies it is discussed in detail. Electromagnetic interference was characterized for ion engines. The electromagnetic compatibility of ion thrusters with spacecraft instruments was determined. The effects of ion thruster plumes on spacecraft were studied with particular emphasis on external surface currents.

Carruth, M. R., Jr.↗
NASA NTRS1981

Interactions between a spacecraft and an ion thruster produced environment

The electron bombardment ion thruster is a candidate propulsion device for several proposed interplanetary missions. A comet rendezvous mission is expected to be the first use of a Solar Electric Propulsion System (SEPS). Because this is the first use of such a system, it is necessary to understand the interactions between the spacecraft and the environment produced by the SEPS. A preliminary assessment of the interactions between a thruster produced environment and the Comet Rendezvous spacecraft, including its science instruments, is presented which concludes that compatibility between the SEPS and the spacecraft can be obtained.

Carruth, M. R., Jr.↗
NASA NTRS1980

Pointing control for the International Comet Mission

The design of the pointing control system for the proposed International Comet Mission, intended to fly by Comet Halley and rendezvous with Comet Tempel-2 is presented. Following a review of mission objectives and the spacecraft configuration, design constraints on the pointing control system controlling the two-axis gimballed scan platform supporting the science instruments are discussed in relation to the scientific requirements of the mission. The primary design options considered for the pointing control system design for the baseline spacecraft are summarized, and the design selected, which employs a target-referenced, inertially stabilized control system, is described in detail. The four basic modes of operation of the pointing control subsystem (target acquisition, inertial hold, target track and slew) are discussed as they relate to operations at Halley and Tempel-2. It is pointed that the pointing control system design represents a significant advance in the state of the art of pointing controls for planetary missions.

Leblanc, D. R.↗
NASA NTRS1981

Solar Maximum Mission - A systems overview

The Solar Maximum Mission (SMM), or the central effort of the Solar Maximum Year research endeavor is discussed. The mission's attempt to exploit the synergistic advantages of correlated data to obtain a complete picture of solar phenomena is stressed, as is the coordination provided by a world-wide network of ground-based observations. The prominent features of the SMM observatory, including the payload module and the solar-array system, are shown diagramatically and the science instruments (coronagraph/polarimeter, ultraviolet spectrometer/polarimeter, soft X-ray polychromater) are discussed. Descriptions of the spacecraft's electrical power system, attitude determination and control systems and communications systems are also included. The Experiment Operations Facility, which provides quick response to rapidly changing solar conditions and permits coordination with a multitude of ground observatories and coordinated experiments, is described.

Guha, A. K.↗
NASA NTRS1981

Planetary science with Space Telescope

The capabilities of the Space Telescope observatory which will comprise a 2.4 m primary mirror scheduled for launch into low earth orbit in late 1983 by the Shuttle are discussed. Attention is given to the first generation of science instruments, including two imaging systems, two complementary spectrographs, a high-speed photometer, and a fine guidance/astrometry system. A specific observing program, an intercomparison of Uranus and Neptune, is examined in detail.

Caldwell, J.↗
NASA NTRS1981

A study of central cryogenic cooling system for the comet rendezvous spacecraft

Several science instruments required temperatures between 100 K and 120 K on a proposed Halley Flyby, Tempel-2 Rendezvous Mission. Significant features of the thermal environment are a large variation in heliocentric as well as comet distance, very large solar panels for a Solar Electric Propulsion stage, and the comet dust environment. The best cooling is achieved by one central radiative cooler connected by insulated cryogenic heat pipes to the instruments. The conceptual design is of a single-stage rectangular shielded radiator deployed on a boom some distance from the spacecraft bus and solar panels. Thermal modeling determined sensitivity to solar and comet distance and was used to optimize cooler geometry.

Salazar, R. P.↗
NASA NTRS1981

Spacecraft computer resource margin management

The conduction of the Project Galileo Orbiter, with 18 microcomputers and the equivalent of 360K 8-bit bytes of memory contained within two major engineering subsystems and eight science instruments, requires that the key onboard computer system resources be managed in a very rigorous manner. Attention is given to the rationale behind the project policy, the development stage, the preliminary design stage, the design/implementation stage, and the optimization or 'scrubbing' stage. The implementation of the policy is discussed, taking into account the development of the Attitude and Articulation Control Subsystem (AACS) and the Command and Data Subsystem (CDS), the reporting of margin status, and the response to allocation oversubscription.

Larman, B. T.↗
NASA NTRS1982

A scheme for tracking and pointing at small celestial bodies during high velocity encounters

A scheme has been developed and verified for closed-loop tracking and pointing space-borne science instruments at small celestial bodies, such as comets and asteroids, during high velocity encounters. To overcome ephemeris uncertainties for these bodies, the scheme involves sequential estimation of flyby model parameters. The design consists of a two-axis gimballed platform mounted on a three-axis stabilized spacecraft. A platform-mounted optical tracker provides closed-loop target measurements and precision micro-step actuators enable high-rate platform slewing. For comet missions which involve dust particle impact disturbances, a dual-mode attitude control scheme is presented for minimizing transient response time.

Burdick, G. M.↗
NASA NTRS1982

Mars Orbiter Study. Volume 1: Summary

Spacecraft system and subsystem designs were developed at the conceptual level to perform either of two Mars orbiter missions, a climatology mission and an aeronomy mission. The HS 376 spacecraft is the basis for the design because it has the lowest cost due to its production line status. The mission design, science instrument accommodation, and spacecraft design are summarized.

Drean, R.↗
NASA NTRS1983

Design of the Galileo remote science pointing actuators

This paper describes the two actuators developed for pointing the remote science instruments from the spinning Galileo spacecraft. Details of the key elements are presented together with their design features and developmental difficulties. Four techniques used for power and signal transfer across the actuators' rotating joints are also discussed.

Osborn, F. W.↗
NASA NTRS1983

Galileo Atmospheric Entry Probe System - Design, development, and test

The overall development of the Galileo Atmospheric Entry Probe System is described. The Probe will be carried to Jupiter by the Galileo Orbiter and released on an entry trajectory 150 days before entry. A complement of seven science instruments will measure the near-Jupiter radiation field and the characteristics of the Jovian atmosphere from a distance of about 5 Jupiter radii above the 1-bar level down to levels in the 10-20-bar range. Probe data are to be transmitted to earth via the Orbiter. System requirements are discussed. Probe design features and those features of the development test program peculiar to entry probes are described.

Givens, J. J.↗
NASA NTRS1983

The effects of Reed-Solomon code shortening on the performance of coded telemetry systems

The theory of Reed-Solomon code shortening in general was developed and the degradation due to shortening in the context of concatenated coding was qualified. It is shown that in the NASA/ESA concatenated system, significant degradations occur only when N 180. A Reed-Solomon code was concatenated with an inner (7, 1/2) convolutional code. Under some circumstances, it would be desirable to use a shorter outer code word length. For example, the format of the data coming from science instruments on board a spacecraft may lend itself naturally to a word length of 200 symbols rather than 223. To accommodate such code word lengths, the Reed-Solomon code can be shortened to an (N, N-32) code where N can be any integer between 33 and 255. Shortening the code, however, changes its performance. On one hand, the amount of redundancy per information symbol increases. Because of this increased redundancy, the amount of energy per information symbol is decreased by code shortening. The overall effect is to degrade the performance of the code.

Deutsch, L. J.↗
NASA NTRS1984

Large Deployable Reflector Science and Technology Workshop. Volume 3: Systems and Technology Assessment

The results of five technology panels which convened to discuss the Large Deployable Reflector (LDR) are presented. The proposed LDR is a large, ambient-temperature, far infrared/submillimeter telescope designed for space. Panel topics included optics, materials and structures, sensing and control, science instruments, and systems and missions. The telescope requirements, the estimated technology levels, and the areas in which the generic technology work has to be augmented are enumerated.

Leidich, C. A.↗
NASA NTRS1984

Technology Panel Reports

Results are presented from five technology panels which convened to identify relevant technologies within their discipline for the Large Deployable Reflector (LDR) and to assess the current and projected state of these technologies. The five panels considered the following topics: optics, materials and structure, sensing and control, science instruments, and systems and missions.

Source record↗
NASA NTRS1984

Telecommunications and data acquisition support for the Pioneer Venus Project: Pioneers 12 and 13, prelaunch through March 1984

The support provided by the Telecommunications and Data Acquisition organization of the Jet Propulsion Laboratory (JPL) to the Pioneer Venus missions is described. The missions were the responsibility of the Ames Research Center (ARC). The Pioneer 13 mission and its spacecraft design presented one of the greatest challenges to the Deep Space Network (DSN) in the implementation and operation of new capabilities. The four probes that were to enter the atmosphere of Venus were turned on shortly before arrival at Venus, and the DSN had to acquire each of these probes in order to recover the telemetry being transmitted. Furthermore, a science experiment involving these probes descending through the atmosphere required a completed new data type to be generated at the ground stations. This new data type is known as the differential very long baseline interferometry. Discussions between ARC and JPL of the implementation requirements involved trade-offs in spacecraft design and led to a very successful return of science data. Specific implementation and operational techniques are discussed, not only for the prime mission, but also for the extended support to the Pioneer 12 spacecraft (in orbit around Venus) with its science instruments including that for radar observations of the planet.

Miller, R. B.↗