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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Pulsed plasma microthruster for synchronous meteorological satellite /SMS/

Two completely self contained variable thrust flight prototype plasma propulsion systems using solid teflon as propellant were designed, built and laboratory tested. The impulse bit amplitude of each thruster is 25 micro lb-sec. Impulse bits can be provided at rates varying from 50 ppm to 110 ppm. The total impulse capability is 400 lb-sec. Only 23 watts of bus power are required at maximum pulse rate. The system was subjected and passed the required vibration schedule and thermal vacuum test after a minor change in capacitor end face material. A 13 million discharge life test of the system was subsequently performed.

Guman, W. J.↗
NASA NTRS1973

The Synchronous Meteorological Satellite /SMS/ system

Description of the fundamental design criteria and operational features of the spacecraft subsystems and ground facilities comprising the SMS program. The main objectives of the program are to provide day and night information on the earth's weather by means of earth imaging, retransmission of imaged data, data collection, data relay, and space environment monitoring. Attention is given to the launch and orbital station-keeping functions, onboard sensors used to provide remote imagery, data transmission from the satellite to command and regional ground stations, and examples of meteorological services resulting from use of this satellite.

Fordyce, D. V.↗
NASA NTRS1975

Data from a synchronous altitude satellite quartz crystal microbalance monitor

Results of one year's operation in orbit of the Quartz Crystal Microbalance Monitor on the ATS-6 satellite are presented. The data indicate a general decreasing trend for the first four and one-half months in orbit. At that time, a sudden increase in beat frequency occurred; this correlates in time with the firing of the North Cesium Ion Engine. A general increase in beat frequency is evidenced since that time. Laboratory tests conducted to investigate the phenomenon are described.

Rogers, J. F.↗
NASA NTRS1975

Synchronous meteorological satellite spin testing

The objective of the end-to-end spin test is to demonstrate both qualitatively and quantitatively that the satellite performs its intended functions under spinning conditions. The test is performed twice per satellite, once during the baseline functional test prior to environmental testing, and once during the final functional test. All satellite functions are demonstrated during the spin test with the exception of solar panel illumination, pyrotechnic device operation, VISSR infrared operation, and auxiliary propulsion system operation.

Mcbrady, D. J.↗
NASA NTRS1995

Cloud Properties Derived From GOES-7 for Spring 1994 ARM Intensive Observing Period Using Version 1.0.0 of ARM Satellite Data Analysis Program

This document describes the initial formulation (Version 1.0.0) of the Atmospheric Radiation Measurement (ARM) program satellite data analysis procedures. Techniques are presented for calibrating geostationary satellite data with Sun synchronous satellite radiances and for converting narrowband radiances to top-of-the-atmosphere fluxes and albedos. A methodology is documented for combining geostationary visible and infrared radiances with surface-based temperature observations to derive cloud amount, optical depth, height, thickness, temperature, and albedo. The analysis is limited to two grids centered over the ARM Southern Great Plains central facility in north-central Oklahoma. Daytime data taken during 5 Apr. - 1 May 1994, were analyzed on the 0.3 deg and 0.5 deg latitude-longitude grids that cover areas of 0.9 deg x 0.9 deg and 10 deg x 14 deg, respectively. Conditions ranging from scattered low cumulus to thin cirrus and thick cumulonimbus occurred during the study period. Detailed comparisons with hourly surface observations indicate that the mean cloudiness is within a few percent of the surface-derived sky cover. Formats of the results are also provided. The data can be accessed through the World Wide Web computer network.

Minnis, Patrick↗
NASA NTRS1975

Multiple rendezvous maneuvers at synchronous altitude

Rendezvous techniques between synchronous satellites were found using a cotangential elliptic phasing (CEP) transfer. This transfer is a closed elliptic orbit which is cotangent to the synchronous orbits of the chase vehicle and target satellite. The cotangent point lies on the line of apsides of the transfer orbit which coincides with the line of intersection of the synchronous orbits. The rendezvous maneuvers accomplish plane changes and phase shifts simultaneously, and these maneuvers are found to be optimal when the plane change is split equally between the velocity increments. The CEP transfer can be extended to several revolutions for a further reduction of fuel usage. A set of synchronous satellites was used in a simulated mission. An optimal sequence for rendezvous among these satellites was established such that the total sum of velocity increments is within the realm of estimated 1980 technology.

Creehan, E. J., Jr.↗
NASA NTRS1971

Coordinated auroral-electron observations from a synchronous and a polar satellite.

The ATS 5 satellite in synchronous orbit and the OV1-18 satellite in a low-altitude polar orbit carried similar experiments to measure auroral-particle fluxes in the energy range from 1/2 to 50 keV. Simultaneous electron flux observations are presented from 5 instances when the OV1-18 passed within a few hundred kilometers of the computed conjugate point to ATS 5. The integral flux levels were found to be generally comparable at the two locations with no evidence for angular distributions highly peaked along the field line. The spectrums were significantly harder at ATS 5 with average energies approximately a factor of 2 higher than at OV1-18. Evidence is presented for a dramatic difference in the shapes of the spectrums at the two locations with smoothly falling relatively featureless spectrums observed at ATS 5 and spectrums with a peak in the few keV range observed at OV1-18. Based on the 5 passes described here, there is evidence that the trapped component of the flux increases more rapidly than the precipitating component during more active times.

Sharp, R. D.↗
NASA NTRS1996

Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

Hoder, Douglas↗
NASA NTRS1967

OPLE experiment

Omega position location equipment feasibility experiment on using Omega navigation system and synchronous satellites for global location and data collection system

DATA ACQUISITION↗