The quality and the precision of the satellite orbit is a critical component of the OSTM mission and provides the central reference frame for the altimeter data. The analysis of OSTM altimeter data and data from TOPEX/Poseidon and Jason-1 requires that the orbits for all three missions be in a consistent reference frame, and calculated with the best possible standards to minimize error and maximize the data return from the 15+ year time series, particularly with respect to the application of

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... suring global sea level change. We discuss the (1) the validation of the tracking systems on OSTM by processing data from all available tracking systems on the spacecraft (SLR, DORIS, GPS and altimeter crossovers); (2) the production of a consistent set of orbits for TOPEX/Poseidon Jason-1 and the OSTM using updated orbit and geophysical model standards. The quality of the dynamic models and the tracking systems are also assessed. Extending the TOPEX, Jason-1, Jason-2 accurate and consistent orbit times series Acknowledgements: We acknowledge the International Laser Ranging Service (ILRS) for their support of Jason-1 & Jason-2, especially during the calibration phase; The new LPOD (SLR) solutions were developed by John Ries (UT/CSR); The DPOD2005 (DORIS) solutions are from P. Willis et al. (2008).