Performance of TOPEX/POSEIDON ''quick-look'' precision orbit determination in the extended mission

The TOPEX/POSEIDON spacecraft, launched on 10 August 1992, has just completed the first year of a three-year extended mission. This year has been characterized by a flight team operating with minimal resources, two satellite safeholds, reduction in Satellite Laser Ranging (SLR) tracking data, and some Global Positioning System Development Receiver (GPSDR) problems. This paper presents a summary of TOPEX/POSEIDON ''quicklook'' orbit determination using GPS and SLR tracking data since the fall of 1995 (beginning of extended mission). The main feature of this process is that orbits are produced with small radial position errors (< 5 cm RMS), on a short production schedule (4 days), with minimal resources. The paper also addresses the extended mission shortcomings and their impact on the precision orbit determination process. The ''quick-look'' orbits are used in support of the Interim Geophysical Data Record (IGDR) production.