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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Coupled orbiting inertial reference systems and Geopotential Research Mission (GRM) geodesy

Two spacecraft, one following the other with a separation of a few hundred kilometers and orbiting at an altitude of 160 km in a 90-degree polar orbit, are used to detect the minute variations in the earth's gravitational field. Housed in a capacitive cavity located at the centroid of the spacecraft is a free-floating metallic spherical proof-mass, which is the sensor controlling the thrusters that nullify all nongravitational forces on the spacecraft. The proof-mass in each spacecraft is the inertial-guidance reference for its host spacecraft, and the proof-masses are coupled together by a millimeter-wave link. This coupled system detects minute changes in the spacecraft's orbital positions and thus measures the anomalies present in the gravitational field of the earth. To derive a global geodetic model of the gravitational field with an amplitude resolution of 1 milligal and a spatial resolution of 100 km requires that the relative velocity between the proof-mass references be determined to within 1 micron/s.

Keating, T.↗
NASA NTRS1980

SPS overview: Requirements, alternatives, and reference system

Basic requirements for the SPS were established. The SPS is considered to be nondepletable with a large positive energy payback over its useful life, capable of base-load operation with no fundamental constraints on capacity. It is compatible with power grids, economically competitive and environmentally acceptable. It should not make excessive use of critical resources, and should be capable of development with reasonable cost, time, and risk. Several of the power generation options and equipment considered are discussed. The reference set of efficiencies defined to represent goals for each step in the power conversion-transmission-reception chain is also described.

Livingston, L. E.↗
NASA NTRS2015

Mars OASIS (Mars Operational Agricultural System for In-Situ Specialization) System Reference Manual

In order to enable long term habitation on planetary surfaces, a means of sustainable food production must be developed. Addressing this need for surface habitats on Mars, the MarsOASIS team has developed a concept for a Martian surface greenhouse for unmanned crop production research as a proof of concept for larger scale food production facilities for manned surface missions. Utilizing in-situ resources such as the Martian atmosphere, sunlight, and UV-C radiation, the greenhouse aims to provide a sustainable method of long-term food production requiring minimal consumable resources. The MarsOASIS system is capable of growing a full life cycle of Outredgeous lettuce with its autonomous control system designed for a unmanned environment, only requiring teleoperation in extreme circumstances. A reduced-scope prototype of MarsOASIS is being developed to test technologies such as a natural/artificial hybrid lighting system, a closed water recycling system, remote teleoperation, and fully autonomous monitoring and control of the greenhouse. The prototype is currently in the final stages of design, with a full demonstration of plant life cycle testing set to occur in summer 2015. Results from this prototype demonstration will help quantify the feasibility of the innovative approaches seen in the MarsOASIS design.

Asa Darnell↗
NASA NTRS1971

The relation of the European Datum to a geocentric reference system

Over 31,000 precision reduced optical observations of GEOS-1 and 2 in 70 two-day orbital arcs were used at Goddard Space Flight Center (GSFC) in a dynamical solution to determine center-of-mass coordinates for 15 tracking stations on the European Datum. Comparisons with the results obtained at Centre National d'Etudes Spatiales (CNES) give agreement of about 1.5 ppm for chord lengths. After considering a scale correction to the European Datum (ED) of 1950 to account for the absence of geoid heights at the time of its reduction, agreement to a few ppm between the CNES/GSFC and the ED chords is obtained. However, a small systematic difference between survey and satellite results remains for stations in southeastern France and Switzerland.

Marsh, J. G.↗
NASA NTRS1974

Stellar tracking attitude reference system

A satellite precision attitude control system was designed, based on the use of STARS as the principal sensing system. The entire system was analyzed and simulated in detail, considering the nonideal properties of the control and sensing components and realistic spacecraft mass properties. Experimental results were used to improve the star tracker noise model. The results of the simulation indicate that STARS performs in general as predicted in a realistic application and should be a strong contender in most precision earth pointing applications.

Klestadt, B.↗
NASA NTRS1976

Use of calibration maneuvers for improved performance of strapdown attitude reference systems

Conventional strapdown configurations require precise knowledge of the orientation of the gyro input axes as well as a moderately large, fast computer to provide inertial attitude. This paper presents the mechanization and discusses the operation and performance of an omnidirectional, strapdown pointing control system called All Sky Pointer which does not require precise gyro alignment or a sophisticated computer. Errors caused by gyro-optical sensor misalignment, gyro-integrator bias, and scale factor error are compensated for by the use of calibration maneuvers. Control and computation are provided by an electronics package utilizing technology similar to that found in hand-held calculators. Simulation results indicate that sub arc-minute pointing performance is possible and pointing errors are reduced by as much as an order of magnitude compared with uncompensated systems.

Lorell, K. R.↗
NASA NTRS1976

Experiment S-213 selenocentric geodetic reference system

Development and implementation of a photogrammetric system was undertaken to provide accurate selenodetic positions and topographic mapping of all areas overflown by orbital spacecraft. The system was installed in the scientific instrument module (SIM) bay of the Apollo command service module (CSM). In theory, this system provided everything a photogrammetrist could want: the position of each exposure station would be obtained from Earth-based tracking; the orientation of each photograph could be computed from the synchronized stellar exposure and the lock-angles determined by preflight calibration; and the scale of each stereomodel would be obtained directly from the altimeter data. Operationally, the data acquisition was adequate, but less than optimum. Systematic errors are believed to be the result of the primitive orbit determination procedures in use at the time of the Apollo 15 mission, inadequate models of the lunar gravity field, and spacecraft oscillations induced by uncoupled thrusting and various activities of the astronauts.

Doyle, F. J.↗
NASA NTRS1977

Flight-control/navigation inertial reference system

The preliminary design of a redundant strapdown navigation system for integrated flight-control/navigation use has been completed. Based on application of tuned-gimbal gyros, a compact configuration (13 in x 13 in x 14 in) has been achieved for fail-operational/fail-operational redundancy. Test data are presented for strapdown system test programs including flight testing of the LN-50 tuned-gimbal gyro system. Testing of a redundant sensor configuration is currently in process. Strapdown gyro development also includes ring laser and nuclear magnetic resonance techniques.

Ebner, R. E.↗
NASA NTRS1980

NASA's 25 kW Power Module - Reference System

The paper deals with a 25-kW orbit-based power system which will be used to expand the Shuttle/Spacelab mission durations in a sortie mode and as an orbit-based platform for spacecraft in a free-flying mode. Consideration is given to operations, system description, capabilities and resources, and growth potential.

Powell, L. E.↗
NASA NTRS1980

Reference System Description

Several candidate antenna configurations are evaluated in terms of weight, efficiency, and structural rigidity. Particular emphasis is given to the waveguide slot array and its application to solar power satellites SPS. The electronic aspects of an SPS specific waveguide slot array are defined.

Lunden, C. D.↗
NASA NTRS1980

SPS silicon reference system

The design analysis of a silicon power conversion system for the solar power satellite (SPS) is summarized. The solar array, consisting of glass encapsulated 50 micrometer silicon solar cells, is described. The general scheme for power distribution to the array/antenna interface is described. Degradation by proton irradiation is considered. The interface between the solar array and the klystron equipped power transmitter is described.

Woodcock, G. R.↗
NASA NTRS1982

Feasibility evaluation and study of adapting the attitude reference system to the Orbiter camera payload system's large format camera

A design concept that will implement a mapping capability for the Orbital Camera Payload System (OCPS) when ground control points are not available is discussed. Through the use of stellar imagery collected by a pair of cameras whose optical axis are structurally related to the large format camera optical axis, such pointing information is made available.

Source record↗
NASA NTRS1983

Protoptype integrated design (Pride) system reference manual. Volume 2: Schema definition

An initial description of an evolving relational database schema is presented for the management of finite element model design and analysis data. The report presents a description of each relation including attribute names, data types, and definitions. The format of this report is such that future modifications and enhancements may be easily incorporated.

Fishwick, P. A.↗