STS-GPS (Space Transportation System - Global Positioning System) Tracking Experiment for Gravitation Estimation: Feasibility Study

摘要

The report summarizes the results of a feasibility study to estimate the gravitation parameters using GPS and IMU measurements onboard the Space Shuttle. The primary objective of the study was to determine the feasibility of estimating perturbations in the gravity vector at the Shuttle altitude to an accuracy of 1 mgal or better (1-sigma) in each axis. A detailed error analysis of the effect of measurement errors on the Shuttle acceleration estimation accuracy was carried out which resulted in the identification of critical errors. Techniques to mitigate the effect of these critical errors were developed. A survey of available hardware to demonstrate the experiment on the Shuttle in 1990-1991 was undertaken and candidate instruments (e.g., GPS receiver, IMU, processor, tape recorder) to support the experiment objectives were identified. Integration of the experiment instrumentation system on the shuttle as a mission kit was carried out. The results of the error analysis, hardware selection and Shuttle integration analysis clearly established the feasibility of the proposed Air Force experiment to map the gravity field in regions where data availability is generally limited. The Air Force STS-GPS Tracking experiment is a low-cost alternative to obtain the gravitation data in restricted areas. Keywords: Space transportation system; Global positioning system; Inertial measurement unit; Gravitation; Space shuttle; Estimation. (JHD)