CoAuthors

Frank Lemoine (NASA GSFC, USA); Douglas Chinn (SGT Inc, USA); Jennifer Beall (Emergent Space Technologies, USA); Stavros Melachroinos (SGT Inc, USA); Brian Beckley (SGT Inc., USA)

The SARAL spacecraft relies on both Satellite Laser Ranging (SLR) and DORIS data precision orbit determination (POD. We have evaluated the POD performance of SARAL by testing the measurement modeling for SLR and DORIS, and by assessing the performance of the force models, particularly with respect to the time-variable gravity modeling and the non-conservative forces. After adjusting the SLR tracking point offsets, and correcting the a priori estimate of the center of mass, we obtain SLR fits of 1.5 cm, with respect to the NASA GSFC SLR-DORIS time-variable gravity model time series. We report on the impact of the use of the Vienna Mapping Function (VMF) and application and other DORIS model improvements. We assess the current state of POD performance using the standard suite of POD tests: RMS of fit, orbit overlaps, intercomparisons with internal and external solutions, and the use of SARAL altimeter crossovers. Finally, we also review the contribution of SARAL DORIS data to the GSC solutions for the terrestrial reference frame, where SARAL has not been included in the GSC submissions for ITRF2013.