The Low-G Accelerometer Calibration System Orbital Accelerometer Experiment. Volume 2. Experiment Analyses and Results

Abstract

Specs Physics Laboratory; Atmoapherlc and Ionospheric physics, radiation from the atmosphere, density and composition of the atmosphere, auroraa and alrglow; magnetoapherlc phyalca, coamlc raya, generation and propagation of plaama waves In the magnetoaphere; aolar physics, studlee of solar magnetic fields; space astronomy, x-ray astronomy; the effects of nuclear explosion«, magnetic storms, and solar activity on the earth's atmosphere. Ionosphere, and magnetosphsre; the effects of optical, electromagnetic, and particulate radiation« In «pace on apace systems. THE AEROSPACE CORPORATION ÄTSf '"'"'•-'--^ --iEl Segundo, California THE LOGACS (Low-G Accelerometer Calibration System) experiment, which contained a miniature electrostatic accelerometer (MESA), was placed in a low-altitude polar orbit on 22 May 1967. The experiment provided approximately 100 hours of acceleration data from which the accelerometer scale factor, accelerometer null bias, and atmospheric drag on the satellite were calculated.Extensive comparisons of the data to various model atmospheres are made. These analyses are the more interesting because of the intense solar and geomagnetic activity during the latter part of the LOGACS flight. From the data, both midlatitude and polar models of atmospheric density have been developed over altitudes for which LOGACS data were available.An analysis was also performed to determine wind characteristics normal to the LOGACS' orbit plane. The results confirm that the atmosphere (up to 100 nmi) has high-velocity winds in the high-latitude regions as a result of the great magnetic storm. Theoretical analysis shows these winds can be described as convective motion due to excessive heating of the polar thermosphere. Models of atmospheric density have been developed over the altitudes for which LOGACS data were available. Both midlatitude models and polar and auroral models are formulated and presented.An analysis was also performed on the LOGACS data to determine the wind magnitude and characteristics normal to the orbit plane of the in experiment. The results confirm that the earth's atmosphere (up to the altitude of 100 nmi) rotates with the earth and find that hiph-velority winds are present in high-latitude regions as a result of the Rreat magnetic storm,

Thermospheric dynamics during the March 22, 1979, magnetic storm: 2. Comparisons of model predictions with observations

“…The night sector is generally characterized by more wavelike structures, indicating phase progression toward the equator, horizontal scales of 1500 km, and density perturbations of 20-40%. The reversals referred to in points 2 and 3 above are also evident in other wind and ion drift measurements during disturbed times [Pearson, 1973;Rees et al, 1985]. These discrepancies may be explicable in part by erroneous positioning, latitudinal extent, or orientation of the driving convection pattern in the TGCM.…”

Thermospheric winds from the satellite electrostatic triaxial accelerometer system

“…erometer calibration system experiment [Feess, 1973;Pearson, 1973]. Major advances in the experimental description of high-latitude winds [Hays et al, 1981;Spencer et al, 1981;Killeen et al, 1982] have been made possible by the polarorbiting Dynamics Explorer satellite (DE 2).…”