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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
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NASA NTRS1980

Measurement of hydroxyl temperatures in the upper atmosphere with a high sensitivity spectrometer

The hydroxyl temperatures in the upper atmosphere were measured over a five-week period in January and February of 1975 and 1976 in order to determine the variation of the rotational temperatures of OH with stratospheric warming events occurring over the New England area. The OH temperatures were also recorded during the summer of 1975 in the Fairfield, Connecticut area. Data show a wide fluctuation in temperatures amounting to as much as a couple of hundred degrees in the course of an evening. A modified Ebert-Fastie spectrometer with a focal length of 1 meter was used to examined the vibration-rotation bands of atmospheric OH in the 7000 to 9000 range. This wavelength was searched and the strongest signal was obtained from the 6-2 band (band head at 8280 A). Graphs show the 6-2 band of the Meinel OH spectrum, the real time and average spectra for the 6-2 band of OH, and rotational temperature of OH vs time for two evenings.

Mcelaney, J. H.↗
NASA NTRS1993

Upper Atmosphere Research Satellite (UARS) attitude accuracy using coarse attitude sensors

The Upper Atmosphere Research Satellite (UARS) uses fixed-head star trackers (FHST's) and inertial reference units (IRU's) to determine and control its attitude. This combination of fine sensors results in attitude knowledge accuracies to better than 10 arc-seconds (1 sigma). UARS also has a variety of coarse attitude sensors on board: the three-axis magnetometer (TAM), the coarse Sun sensor (CSS), the fine Sun sensor (FSS), and the Earth sensor assembly (ESA). By comparing attitude solutions using coarse sensors with FHST-determined attitude solutions, estimates can be made of the accuracy of the coarse sensors. This paper presents the results of an analysis that compares attitude solutions using various combinations of UARS coarse attitude sensor data with FHST attitude solutions.

Krack, K.↗
NASA NTRS1993

Upper Atmosphere Research Satellite attitude disturbances during shadow entry and exit

The Upper Atmosphere Research Satellite (UARS), as with the Landsat-4 and Landsat-5 spacecraft, experiences large attitude disturbances when entering and exiting the Earth's shadow. Previous investigations have provided some evidence linking these disturbances to rapid bending of the solar array but have also raised questions. For example, the magnitudes of the roll attitude disturbances have shown an unmolested asymmetry, and the timing of the disturbances at sunrise appears to disagree with the modeled timing. A better understanding of this phenomenon is important in assessing the implications for UARS science gathering and for future mission design analysis. To this end, UARS attitude, sensor, and actuator data are used to evaluate the disturbances as they vary with solar beta angle and solar array drive angle. The attitude data are examined during specific periods of interest, such as the month in which the solar array was parked in its high-noon position, and are also tracked from the beginning of the mission to determine any trends that may result from changing mass properties due to cryogen boiloff and propellant usage. Attitude rate and torque profiles are derived from inertial reference until data and related to the disturbances seen in the attitude data. The timing of the disturbances with respect to spacecraft sunset and sunrise is characterized to allow event predictions. Stability during the disturbances is discussed in terms of science instrument requirements. Finally, the results are compared with the behavior predicted by models that are based on solar array bending.

Lambertson, M.↗
NASA NTRS1995

Upper Atmosphere Research Satellite Validation Workshop III: Temperature and Constituents Validation

The Upper Atmosphere Research Satellite (UARS) was launched in September 1991. Since that time data have been retrieved continuously from the various instruments on the UARS spacecraft. These data have been processed by the respective instrument science teams and subsequently archived in the UARS Central Data Handling Facility (CDHF) at the NASA Goddard Space Flight Center, Greenbelt, Maryland. This report contains the proceedings from one of the three workshops held to evaluate the progress in validating UARS constituents and temperature data and to document the quality of that data. The first workshop was held in Oxford, England, in March 1992, five and one-half months after UARS launch. The second workshop was held in Boulder, Colorado in October 1992. Since launch, the various data have undergone numerous revisions. In many instances these revisions are a result of data problems identified during the validation workshops. Thus, the formal validation effort is a continually ongoing process.

Grose, William L.↗
NASA NTRS1999

The Upper Atmosphere Research Satellite: From Coffee Table Art to Quantitative Science

The Upper Atmosphere Research Satellite (UARS) has provided an unprecedented set of observations of constituents of the stratosphere. When used in combination with data from other sources and appropriate modeling tools, these observations are useful for quantitative evaluation of stratospheric photochemical processes. This is illustrated by comparing ozone observations from airborne Differential Absorption Lidar (DIAL), from the Polar Ozone and Aerosol Measurement (POAM), from the Microwave Limb Sounder (MLS), and from the Halogen occultation Experiment (HALOE) with ozone fields generated with a three dimensional model. For 1995-96, at polar latitudes, observations from DIAL flights on December 9 and January 30, and POAM and MLS between late December and late January are compared with ozone fields from the GSFC 3D chemistry and transport model. Data from the three platforms consistently show that the observed ozone has a negative trend relative to the modeled ozone, and that the trend is uniform in time between early and mid winter, with no obvious dependence on proximity to the vortex edge. The importance of chlorine catalyzed photochemistry to this ozone loss is explored by comparing observations from MLS and HALOE with simulations for other northern winters, particularly 1997-98.

Douglass, Anne R.↗