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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

The relationship between the IMF B(y) and the distant tail (150-238 Re) lobe and plasmasheet B(y) fields

The relationships between the Solar Magnetospheric (SM) y-component of the interplanetary magnetic field (IMF) and the lobe and plasmasheet magnetic fields have been studied for the two ISEE-3 deep tail passes. It is found that for positive sector IMFs, 13 percent of the interplanetary magnetic field penetrates into the aberrated north-dawn and south-dusk lobe quadrants, and about the same amount in the north-dusk and south-dawn lobe quadrants for negative sector IMFs. For the above cases, field penetration is significantly less for opposite polarity IMFs. The former results are generally consistent with open magnetospheric models, but the latter (the lack of response in certain quadrants) are unexplained by theory at this time. If the magnitude of the plasmasheet B(y) fields are related to plasma pressure anisotropies, very small anisotropies of about 1.01 are expected.

Tsurutani, B. T.↗
NASA NTRS2009

Where is the Best Site on Earth? Domes A, B, C, and F, and Ridges A and B

The Antarctic plateau contains the best sites on earth for many forms of astronomy, but none of the existing bases were selected with astronomy as the primary motivation. In this paper, we try to systematically compare the merits of potential observatory sites. We include South Pole, Domes A, C and F, and also Ridge B (running NE from Dome A), and what we call Ridge A (running SW from Dome A). Our analysis combines satellite data, published results and atmospheric models, to compare the boundary layer, weather, free atmosphere, sky brightness, pecipitable water vapour, and surface temperature at each site. We find that all Antarctic sites are likely compromised for optical work by airglow and aurorae. Of the sites with existing bases, Dome A is the best overall; but we find that Ridge A offers an even better site. We also find that Dome F is a remarkably good site. Dome C is less good as a thermal infrared or terahertz site, but would be able to take advantage of a predicted OH hole over Antarctica during Spring.

Suanders, Will↗
NASA NTRS1979

Evaluation and Analysis of SEASAT-A Scanning Multichannel Microwave Radiometer (SSMR) Antenna Pattern Correction (APC) Algorithm. Sub-task 4: Interim Mode T Sub B Versus Cross and Nominal Mode T Sub B

The brightness temperature data produced by the SMMR Antenna Pattern Correction algorithm are evaluated. The evaluation consists of: (1) a direct comparison of the outputs of the interim, cross, and nominal APC modes; (2) a refinement of the previously determined cos beta estimates; and (3) a comparison of the world brightness temperature (T sub B) map with actual SMMR measurements.

Kitzis, J. L.↗
NASA NTRS1986

SQUID readout and ultra-low magnetic fields for Gravity Probe-B (GP-B)

The superconducting readout system to be used for resolving 0.001 arcsec changes in the gyroscope spin direction in the Relativity Gyroscope (GP-B) experiment is described. This system couples the London magnetic moment flux of the spinning gyro to a low noise superconducting quantum interference device (SQUID) detector. Resolution limits and noise performance of the detection system are discussed, and improvements obtained and expected with advanced SQUIDs are presented. Also described is the novel use of superconducting magnetic shielding techniques to obtain a 250 dB attenuation of the earth's magnetic field at the location of the gyroscopes. In this approach, expanded superconducting foil shields are coupled with fixed cylindrical superconducting shields and special geometric considerations to obtain the extremely high attenuation factor required. With these shielding techniques, it appears that the 0.5-Gauss earth field (which appears to the gyroscopes as an ac field at the satellite roll rate) can be reduced to the 10 to the -13th G level required by the experiment. Recent results concerning improvements in the performance of the superconducting foil techniques obtained with the use of a new computer-controlled cooling system are presented.

Lockhart, James M.↗
NASA NTRS1988

Unique cryogenic features of the Gravity Probe B (GP-B) experiment

Cryogenic designs to simplify launch-pad operations for the Gravity Probe B experiment (an orbital test of Einsteins's general theory of relativity using gyroscopes) while achieving an orbital lifetime of two years are discussed. The proposed system allows the probe to be loaded into a cold dewar, provides good structural support and thermal contact after insertion, and eliminates the need for a pumping system during ground hold. The use of a gamma alumina/epoxy minimizes the parasitic heat loads into the dewar through the telescope aperture and the tank supports.

Parmley, Richard T.↗
NASA NTRS1971

The gamma ray experiment for the Small Astronomy Satellite B (SAS-B)

A magnetic core digitized spark chamber gamma ray telescope has been developed for satellite use. The detector has the following characteristics: effective area = 500 cu/cm, solid angle = 1/4 SR; efficiency (high energy) = 0.29; and time resolution of better than two milliseconds.

Fichtel, C. E.↗
NASA NTRS2021

Mass and density of the transiting hot and rocky super-EarthLHS 1478 b (TOI-1640 b)

One of the main objectives of the Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of small rocky planets around relatively bright nearby stars. Here, we report the discovery and characterization of the transiting super-Earth planet orbiting LHS 1478 (TOI-1640). The star is an inactive red dwarf (J∼9.6mag and spectral type m3 V) with mass and radius estimates of 0.20±0.01 M and 0.25±0.01R, respectively, and an effective temperature of 3381±54K. It was observed by TESS in four sectors. These data revealed a transit-like feature with a period of 1.949 days. We combined the TESS data with three ground-based transit measurements, 57 radial velocity (RV) measurements from CARMENES, and 13 RV measurements from IRD, determining that the signal is produced by a planet with a mass of 2.33+0.20−0.20M and a radius of 1.24+0.05−0.05R. The resulting bulk density of this planet is 6.67 g cm−3, which is consistent with a rocky planet with an Fe- and MgSiO3-dominated composition. Although the planet would be too hot to sustain liquid water on its surface (its equilibrium temperature is about ∼595 K, suggesting a Venus-like atmosphere), spectroscopic metrics based on the capabilities of the forthcomingJames WebbSpace Telescope and the fact that the host star is rather inactive indicate that this is one of the most favorable known rocky exoplanets for atmospheric characterization.

M. G. Soto↗