93-154
Early results from the TOPEX/POSEIDONGPS Precise Orbit Determination Demonstration,
Willy Bertiger*, Sien Wu**, Tom Yunck***, Ron Muellerschoen*, Pascal Willis****, Yoaz Bar-Sever*, Ab Davis*****, Bruce Haines*, Tim Munson*, Steve Lichten******, and Rick Sunseri*,
Abstract
TOPEX/POSIEDON a US/French oceanographic mission launched in August 1992, is the first earth satellite to carru a multi-channel, dual frequency GPS receiver capable of making high precision P-code pseudorange and carrier phase measurements. The receiver was placed on TOPEX/POSIEDON as an experiment to demonstrate the potential of differential GPS tracking for subdecimeter orbit determination. In addition to the receiver, TOPEX/POSIEDON carries two flight-proven tracking systems to provide the operational precise orbit determination needed to meet the mission scientific requirements. These include a French-built one-way Doppler system known as DORIS and a circular ring of laser retroreflectors. Here we evaluate the quality of the GPS-determined orbits by examining post-fit residuals, orbit comparisons with DORIS, and orbit repeatability on overlapping data arcs. Overlapping data arcs with 6 hours of common data out of a 30-hour arc have an average RMS altitude difference of 3.0 cm for 9 arcs. The average RMS altitude difference about the mean with a DORIS orbit was 5.7 cm.
* Member of the Technical Staff, Tracking Systems and Applications Section, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.
** Technical Group Leader, Tracking Systems and Applications Section, Jet Propulsion Laboratory,4800 Oak Grove Drive, Pasadena, California 91109.
*** Deputy Section Manager, Tracking Systems and Applications Section, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.
****Head, Geodetic Reasearch Laboratory, Institut Geographique National (IGN), France
*****Topex-GPS Experiment Manager, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.
******Group Supervisor, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.