Analysis and Programming for Research in the Physics of the Upper Atmosphere

A versatile density model for the upper atmosphere (DENMOD) has been developed to provide quantitative density data. This software package consolidates recent atmospheric density models for convenient usage. Computations in the Jacchia 1977 Model have been streamlined. Methods are presented for comparative evaluations of various recent atmospheric density models, such as those included in DENMOD, with respect to the precision of satellite position predictions. These comparisons are benchmarked by accurate satellite tracking data obtained from CW Doppler beacon measurements. AFGL ephemerides systems are described which provide efficient calculations of satellite orbits expressed in a variety of forms. The utility of these programs has been expanded by adding the capability for performing ancillary calculations. These include evaluation of occultation conditions and viewing conditions for configurations of multiple observing platforms. With addition of magnetic field models which include field line tracing routines, these software systems can be used to evaluate the time-histories of various types of geomagnetic images (or footprints) of satellites as they traverse their orbits. Improvements have been made in the AFGL Rocket Trajectory System, a software system which provides statistical filtering of radar data for rocket launches. New rocket types have been added to the system's repertoire of thrust models. (Author)