A comparison of operationally determined atmospheric densities from satellite orbit solutions and the exospheric temperature from the JacchiaRoberts model
Abstract
Operational orbit determination by the Flight Dynamics Division at the Goddard Space Flight Center has yielded a data base of orbit solutions covering the onset of solar cycle 22. Solutions for nine satellites include an estimated drag adjustment parameter (rho sub 1) determined by the Goddard Trajectory Determination System (GTDS). The rho sub 1 is used to evaluate correlations between density variations and changes in the following: 10.7centimeter wavelength solar flux (F sub 10.7), the geomagnetic index A sub p, and two exospheric temperatures (T sub c and T sub infinity) adapted from the JacchiaRoberts atmospheric density model in GTDS. T sub c depends on the daily and 81day centered mean F sub 10.7; T sub infinity depends on T sub c and the geomagnetic index K sub p values. The highest correlations are between density and T sub infinity. Correlations with T sub c and F sub 10.7 are lower by 9 and 10 percent, respectively. For most cases, correlations with A sub p are considerably lower; however, significant correlations with A sub p were found for some highinclination, moderatealtitude orbits. Results from this analysis enhance the understanding of the drag model and the accommodation of atmospheric density variations in the operational orbit determination support. The degree of correlation demonstrates the sensitivity of the orbit determination process to drag variations and to the input parameters that characterize aspects of the atmospheric density model. To this extent, the degree of correlation provides a measure of performance for methods of selecting or modeling the thermospheric densities using the solar F sub 10.7 and geomagnetic data as input to the process.
 Publication:

Flight Mechanics/Estimation Theory Symposium, 1990
 Pub Date:
 December 1990
 Bibcode:
 1990fmet.symp..171W
 Keywords:

 Atmospheric Density;
 Atmospheric Models;
 Correlation;
 Drag;
 Goddard Trajectory Determination System;
 Orbit Calculation;
 Thermosphere;
 Aerodynamics;
 Data Bases;
 Estimating;
 Geomagnetism;
 Sensitivity;
 Solar Cycles;
 Solar Flux;
 Astrodynamics