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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

(abstract) Geology of the Venera and Vega Landing Sites

Geologic mapping of the seven Venera/Vega landing sites (radius of error = 150 km) using Magellan data has shown that the dominant type of terrain at these sites is plains. At the Venera 8 and 13 sites, where a nontholeiitic composition was measured for the surface material, the Magellan imagery shows that both these sites have unusual volcanic features associated with them, such as steep sided domes and coronalike features. At the other five sites, where no peculiar volcanic activity occurred within the landing circle, the landers measured geochemical signatures of tholeiitic basalts. This association between unusual volcanic activity and nontholeiitic composition suggests that the geochemistry measured by the landers correlates well with the morphology seen in the Magellan imagery. A strong correlation also exists between the SAR imagery and the TV panoramas taken by the Venera 9, 10, 13, and 14 landers. Based on Magellan data and the lander geochemical and TV panoramas, we have been able to suggest the most likely material in the Magellan imagery sampled by the landers.

Venera↗
NASA NTRSDate not supplied

Prelaunch Characterization and Performance of JPSS-3 VIIRS Reflective Solar Bands

The Joint Polar Satellite System 3 (JPSS-3) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is the fourth in a series (S-NPP VIIRS launched in October 2011, JPSS-1 VIIRS launched in November 2017, and JPSS-2 VIIRS currently undergoing spacecraft integration) of highly advanced polar-orbiting environmental satellites. JPSS-3 VIIRS underwent a comprehensive sensor-level Thermal Vacuum (TV) testing at the Raytheon Technologies El Segundo facility in the fall of 2020. While the test program provided characterization for many spatial, spectral, and radiometric aspects of the VIIRS sensor performance, this paper focuses on the radiometric performance of the 14 reflective solar bands (RSB) that cover the wavelength range from 0.41 to 2.3 μm. Key calibration parameters, such as the instrument gain, signal-to-noise ratio (SNR), dynamic range and radiometric uniformity, were derived in a TV environment for both the primary and redundant electronics at three instrument temperature plateaus: cold, nominal, and hot. This paper shows that all the JPSS-3 VIIRS RSB detectors have been well characterized, with the key performance metrics being comparable to those of the previous VIIRS instruments. Comparison of radiometric performance to sensor requirements, as well as a summary of key sensor testing and performance issues, will also be presented.

JPSS-3↗
NASA NTRSDate not supplied

Molecular Accumulation during JWST’s Optical Telescope Cryogenic Thermal Vacuum Testing

Maintaining molecular cleanliness during the JWST’s Optical Telescope/Instrument Module (OTIS) Cryogenic Thermal Vacuum (TV) test campaign was critical to the success of its optical mission on orbit. In the thermal vacuum tests leading up to the final cryogenic test to validate the OTIS flight hardware, NASA Johnson Space Center’s (JSC’s) TV Chamber A was fully characterized for molecular contamination. It was found to contain common volatile condensable materials (VCM), including hydrocarbons, plasticizers, and silicones, all of which absorb in JWST’s infrared wavelength region. Due to the risks involved, cleaning molecular contamination from the OTIS mirrors was not an option and heating the Primary Mirror (PM) segments would have also been a risky and expensive endeavor. As a result, a monitoring process was developed and implemented during four different Pathfinder or risk reduction tests that were scheduled to occur prior to the flight hardware test. The goal was to quantify and assess the risk of molecular contamination depositing on the PM resulting from relatively warm chamber shrouds “leading” colder PM mirrors during warmup, by a margin of 10-50 Kelvin (K). This was accomplished using Cryogenic Quartz Crystal Microbalances (CQCMs), held at temperatures slightly cooler than the segments to signal the onset of contamination events. Per the JWST Contamination Control Plan (CCP)1, the total Primary Mirror molecular allocation requirement was 50 angstroms. In all tests, the results showed an average accumulated molecular contamination of <10 angstroms.

optics↗
NASA NTRSDate not supplied

Molecular Accumulation during JWST’s Optical Telescope Cryogenic Thermal Vacuum Testing

Maintaining molecular cleanliness during the JWST’s Optical Telescope/Instrument Module (OTIS) Cryogenic Thermal Vacuum (TV) test campaign was critical to the success of its optical mission on orbit. In the thermal vacuum tests leading up to the final cryogenic test to validate the OTIS flight hardware, NASA Johnson Space Center’s (JSC’s) TV Chamber A was fully characterized for molecular contamination. It was found to contain common volatile condensable materials (VCM), including hydrocarbons, plasticizers, and silicones, all of which absorb in JWST’s infrared wavelength region. Due to the risks involved, cleaning molecular contamination from the OTIS mirrors was not an option and heating the Primary Mirror (PM) segments would have also been a risky and expensive endeavor. As a result, a monitoring process was developed and implemented during four different Pathfinder or risk reduction tests that were scheduled to occur prior to the flight hardware test. The goal was to quantify and assess the risk of molecular contamination depositing on the PM resulting from relatively warm chamber shrouds “leading” colder PM mirrors during warmup, by a margin of 10-50 Kelvin (K). This was accomplished using Cryogenic Quartz Crystal Microbalances (CQCMs), held at temperatures slightly cooler than the segments to signal the onset of contamination events. Per the JWST Contamination Control Plan (CCP)1, the total Primary Mirror molecular allocation requirement was 50 angstroms. In all tests, the results showed an average accumulated molecular contamination of <10 angstroms.

molecular, contamination, thermal vacuum, cryogeni↗
NASA NTRS1963

The fm demodulator with negative feedback

This paper describes the design and theory of operation of the wideband FM demodulator with feedback (FMFB receiver) used at the Andover, Maine, earth station for Telstar satellite communications tests. Performance data for the FMFB receiver indicate a clear advantage over the conventional FM receiver in many cases. The principal advantage lies in the ability of the FMFB receiver to raise the threshold at which “breaking” occurs for TV and other wideband signals.

TELSTAR SATELLITE↗
NASA NTRS1965

A mars spacecraft photographic system.

Spacecraft TV system for topographic reconnaissance of Mars surface consisting of single camera and slow-scan vidicon shutter system

SPACECRAFT TELEVISION↗
NASA NTRS1966

Screen of cylindrical lenses produces stereoscopic television pictures

Stereoscopic television pictures are produced by placing a colorless, transparent screen of adjacent parallel cylindrical lenses before a raster from two synchronized TV cameras. Alternate frames from alternate cameras are displayed. The viewers sensory perception fuses the two images into one three-dimensional picture.

Nork, C. L.↗
NASA NTRS1966

Circular, explosion-proof lamp provides uniform illumination

Circular explosion-proof fluorescent lamp is fitted around a TV camera lens to provide shadowless illumination with a low radiant heat flux. The lamp is mounted in a transparent acrylic housing sealed with clear silicone rubber.

Source record↗
NASA NTRS1965

Television system.

Mariner IV TV system for photographing Mars surface during flyby

PLANETARY ORBIT↗
NASA NTRS1965

Geophysical observations from Nimbus I.

Cloud height, ground- and sea-surface temperatures, ice forms, terrain features and soil moisture information from Nimbus I satellite equipped with TV cameras and IR radiometer

NIMBUS SATELLITE↗
NASA NTRS1966

Solar-pumped modulated laser.

Solar pumping and modulation of various laser materials for deep space communication, noting TV PICTURE transmission

SOLAR ENERGY↗
NASA NTRS1966

Observations on pulsating auroras.

Pulsating auroras observed near equatorward boundary of auroral displays during postbreakup phase with image orthicon TV and photometers

AURORAL ACTIVITY↗