Initial Orbit Determination Results for Jason‐1: Towards a 1 cm Orbit

ABSTRACT The U.S/French Jason-1 oceanographic mission iscarrying state-of-the-art radiometric tracking systems(GPS and DORIS) to support precise orbit determination(POD) requirements. The performance of the systems isstrongly reflected in the early POD results. Results ofboth internal and external (e.g., satellite laser ranging)comparisons indicate that the RMS radial accuracy is inthe range of 1—2 cm. We discuss the POD strategyunderlying these orbits, as well as the challenging issuesthat bear on the understanding and characterization of anorbit solution at the 1-cm level. We also describe a GPS-based system for producing science-quality orbits in nearreal time in order to support emerging applications inoperational oceanography. INTRODUCTION The Jason-1 spacecraft was launched from VandenbergAir Force Base on December 7, 2001, and has beensuccessfully placed in a circular, 1335-km orbit aroundthe Earth. A joint U.S./French oceanographic mission,Jason-1 represents the first in a series of altimetricmissions designed to carry on the legacy of precise sea-*To appear in the

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