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The Mars Premier mission that was to be flown in 2007 by CNES in cooperation with NASA/JPL included a rendezvous experiment to be performed in Mars orbit to validate key technologies applicable to a Sample Return mission. The experiment goal was to demonstrate the capability to detect and track a sample canister at long range and validate terminal rendezvous strategies including a capture.

This paper primarily addresses positioning performance improvements from in-situ orbiter to rover doppler tracking compared to DTE doppler only.

Unexpected energy increases during Earth flybys of both the Galileo and Near Earth Asteroid Rendzvous (NEAR) spacecraft have drawn evidence of spacecraft trajectory modeling errors, an unknown perturbing force or failure of Newtonian gravity.

This paper extends earlier analysis for autonomous orbit determination and control of Earth orbiting spacecraft. The earlier analysis was limited to a single spacecraft with a ground track repeat requirement. This work shows that a similar technique is applicable for two spacecraft flying in formation. Tracking and orbit determination functions are performed using the Global Positioning System (GPS).

A reduced dynamic filtering strategy that exploits the unique geometric strength of the Global Positioning System (GPS) to minimize the effects of force model errors has yielded orbit solutions for TOPEX/POSEIDON which appear accurate to better than 3 cm (1 sigma) in the radial component. Reduction of model error also reduces the geographic correlation of the orbit error. With a traditional dynamic approach, GPS yields radial orbit accuracies of 4-5 cm, comparable to the accuracy delivered by satellite laser ranging and the Doppler orbitography and radio positioning integrated by satellite (DORIS) tracking system. A portion of the dynamic orbit error is in the Joint Gravity Model-2 (JGM-2); GPS data from TOPEX/POSEIDON can readily reveal that error and have been used to improve the gravity model.

A.

When Topex/Poseidon, is launched in June 1992, the joint United States/French oceanographic satellite mission will carry a developmental Global Positioning System (GPS) receiver on board to support the planned GPS demonstration experiment. The navigation operations aspect of the demonstration will develop software and operational procedures for the GPS Data Processing Facility (GDPF) at NASA's Jet Propulsion Laboratory. This paper presents simulations and covariance analysis of operational scenarios in support of the GDPF. Multi-orbit filter techniques using GPS carrier phase and P-code pseudo-range are studied both to tune the filter parameters and to determine feasible arc lengths for use in operations. In addition, a baseline operational scenario is presented with performance results given in terms of end-to-end processing times and computational loading based on a prototype version of the operational software.