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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 NTRS1994

Construction of temperature compensated constant voltage (VT) curves for super Ni-Cd (tm) cells

Tests to establish current-voltage characteristics at selected temperatures for 9 a-h Super Nickel-Cadmium cells were conducted at Hughes Industrial Electronics Company's Electron Dynamics Division (HIEC/EDD) under sponsorship of NASA/GSFC through their prime spacecraft contractors Fairchild Space (SMEX/SAMPEX) and TRW (TOMSEP). Curves were constructed using techniques established by Webster, Ford, et al, at NASA/GSFC in the late 1960's - early 1970's time period for conventional nickel cadmium cells used on OAO and OSO aircraft. The NASA/GSFC techniques were slightly modified by HIEC/EDD to fit the Super Ni-Cd situation.

Baer, David A.↗
NASA NTRS1993

COMET service module capillary pumped loop thermal control system test results

The COMmercial Experiment Transporter (COMET) is a satellite that will be launched aboard the Conestoga rocket. The COMET Service Module is designed, integrated and tested by Defense Systems Incorporated for Westinghouse Commercial Space. The Capillary Pumped Loop (CPL) was integrated into the Service Module by OAO Corporation for Defense Systems Incorporated. The Service Module's primary function is to carry payloads to space, providing them with utilities such as tightly controlled thermal environment, electrical power, attitude control, data management, and communications while in orbit. This paper presents the results of functional and performance testings of the CPL Thermal Control System (TCS) for the COMET Service Module.

Yun, James Seokgeun↗
NASA NTRS1997

Observations of Accreting Pulsars

We summarize 5 years of continuous monitoring of accretion-powered pulsars with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. Our 20-70 keV observations have determined or refined the orbital parameters of 13 binaries, discovered five new transient accreting pulsars, measured the pulsed flux history during outbursts of 12 transients (GRO J1744-28, 4U 0115+634, GRO J1750-27, GS 0834-430, 2S 1417-624, GRO J1948+32, EXO 2030+375, GRO J1008-57, A0535+26, GRO J2058+42, 4U 1145-619, and A1118-616), and also measured the accretion torque history during outbursts of six of those transients whose orbital param- eters were also known. We have also continuously measured the pulsed flux and spin frequency for eiaht persistently accreting pulsars (Her X-1, Cen X-3, Vela X-1, OAO 1657-415, GX 301-2, 4U 1626-67, 4U 1538-52, and GX 1+4). Because of their continuity and uniformity over a long baseline, BATSE observations have provided new insights into the long-term behavior of accreting magnetic neutron stars. We have found that all accreting pulsars show stochastic variations in their spin frequencies and luminosities, including those displaying secular spin-up or spin-down on long timescales, which blurs the con- ventional distinction between disk-fed and wind-fed binaries. Pulsed flux and accretion torque are strongly correlated in outbursts of transient accreting pulsars but are uncorrelated, or even anti- correlated, in persistent sources. We describe daily folded pulse profiles, frequency, and flux measurements that are available through the Compton Observatory Science Support Center at NASA/Goddard Space Flight Center.

Bildsten, Lars↗
NASA NTRS1997

Observations of Accreting Pulsars

We summarize five years of continuous monitoring of accretion-powered pulsars with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. Our 20-70 keV observations have determined or refined the orbital parameters of 13 binaries, discovered 5 new transient accreting pulsars, measured the pulsed flux history during outbursts of 12 transients (GRO J1744-28, 4U 0115+634, GRO J1750-27, GS 0834-430, 2S 1417-624, GRO J1948+32, EXO 2030+375, GRO J1008-57, A 0535+26, GRO J2058+42, 4U 1145-619 and A 1118-616), and also measured the accretion torque history of during outbursts of 6 of those transients whose orbital parameters were also known. We have also continuously measured the pulsed flux and spin frequency for eight persistently accreting pulsars (Her X-1, Cen X-3, Vela X-1, OAO 1657-415, GX 301-2, 4U 1626-67, 4U 1538-52, and GX 1+4). Because of their continuity and uniformity over a long baseline, BATSE observations have provided new insights into the long-term behavior of accreting magnetic stars. We have found that all accreting pulsars show stochastic variations in their spin frequencies and luminosities, including those displaying secular spin-up or spin-down on long time scales, blurring the conventional distinction between disk-fed and wind-fed binaries. Pulsed flux and accretion torque are strongly correlated in outbursts of transient accreting pulsars, but uncorrelated, or even anticorrelated, in persistent sources. We describe daily folded pulse profiles, frequency, and flux measurements that are available through the Compton Observatory Science Support Center at NASA-Goddard Space Flight Center.

Bildsten, Lars↗
NASA NTRS2000

XTE J1906+09 Observations with RXTE

The 89 s pulsar XTE J1906+09 was serendipitously discovered in a 1996 observation of the soft gamma repeater SGR 1900+14. Two outbursts, in 1996 September and 1998 September have been reported to date. Since this system appears to be transient, it is likely in a Be/X-ray binary, accreting material from a circumstellar disk around its companion. Preliminary pulse timing analyses of RXTE data from the 1998 September outburst revealed an orbital signature consistent with either (i) a low-eccentricity, short period orbit, similar to OAO 1657-415 or (ii) periastron passage in a longer orbital period, higher eccentricity Be/X-ray binary system. No companion has been identified to date due to the large 2 feet error radius of the current best position. SGR 1900+14 has been regularly monitored with RXTE since 1998. Because XTE J1906+09 is only 33 feet away, it often shares the RXTE/PCA field of view with SGR 1900+14, giving us a large number of archival PCA observations. We will present results of a search of RXTE data for outbursts of XTE 1906+09, including histories of pulse frequency, 2-30 keV intensity, pulse profiles, and energy spectra. Results of a pulse timing analysis of the detected outbursts will also be presented.

Wilson, Colleen A.↗
NASA NTRS1993

A Contracign out Success Story

This paper is based on the highly successfull Mission and Computing Support (MACS) Contract, between the Jet Propulsion Laboratory (JPL) and OAO Corporation, which encompasses a comprehensive set of work for information systems and services. JPL awarded the MACS contract in 1988 and saw very succeful operation during the first five years which were recently completed.

Contracting Outsourcing↗
NASA NTRS2012

Observations of Accreting Pulsars with the FERMI-GBM

The Gamma-ray Burst Monitor (GBM) on-board Fermi comprises 12 NaI detectors spanning the 8-1000 keV band and 2 BGO detectors spanning the 100 keV to 40 MeV band. These detectors view the entire unocculted sky, providing long (approximately 40 ks/day) observations of accreting pulsars daily, which allow long-term monitoring of spin-frequencies and pulsed uxes via epoch-folded searches plus daily blind searches for new pulsars. Phase averaged uxes can be measured using the Earth occultation technique. In this talk I will present highlights of GBM accretion-powered pulsar monitoring such as the discovery of a torque reversal in 4U1626-67, a high-energy QPO in A0535+26, and evidence for a stable accretion disk in OAO 1657-415.

Wilson-Hodge, Colleen↗
NASA NTRS2012

Assess Calibration Consistency of MODIS and AVHRR Thermal Infrared Bands Using SNO Observations Corrected for Atmospheric Effects

Monitoring environmental changes from space requires extremely well-calibrated observations to achieve the necessary high accuracy and stability. The calibration differences between the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Very High Resolution Radiometer (AVHRR) thermal bands provide a valuable quality assessment of the instrument performance. This letter compares the calibration differences between the Aqua MODIS and NOAA-18 AVHRR bands at 11.0 and 12.0 /Lm using simultaneous nadir overpass observations obtained in nearly parallel orbits. Impacts due to the relative spectral-response differences between the two sensors are estimated by MODTRAN simulations with real-time atmospheric profiles of temperature, water vapor, atmospheric pressure and ozone, and surface skin temperatures. Results show that the temperature difference after the removal of atmospheric impacts is within 0.30 K (or 0.40% in radiance) across the effective calibration range (or the 1l.0 l'm band/channel. For the 12.0 pm band, the differences are OAO K (or 0.50%) at the typical radiance and up to 0.70 K (or 0.90%) close to the maximum radiance, indicating an excellent calibration consistency between MODIS and AVHRR for both bands.

Wu, Aisheng↗