HR: 1340h
AN: SF53A-0735    [Abstracts]
TI: Formation Flying of LEO Satellites Using GPS
AU: * Svehla, D
EM: svehla@bv.tum.de
AF: Forschungseinrichtung Satellitengeod\"asie, TU Munich, Arcisstrasse 21, Munich, D-80333 Germany
AU: Rothacher, M
EM: rothacher@bv.tum.de
AF: Forschungseinrichtung Satellitengeod\"asie, TU Munich, Arcisstrasse 21, Munich, D-80333 Germany
AB: The GRACE satellites can be considered as the first formation flying of two LEO satellites in space equipped with GPS receivers used for precise orbit determination. Since the distance between these two satellites is relatively small, the GRACE satellites allow for the first time to form a highly accurate GPS baseline in space that is uninterrupted and continues in time. In the case of several LEO satellites in space like, e.g., GRACE, COSMIC and SWARM, the GPS baselines form a LEO network in space independent of the ground network. We show different zero- and double-difference, kinematic and reduced-dynamic POD approaches for the GRACE formation flying over two years. We compare several ambiguity resolution strategies for the GPS baseline in space like Melbourne-Wbbena wide-laning with narrow-lane bootstrapping and the quasi-ionosphere-free (QIF) approach and demonstrate that 95%-100% of all ambiguities can be resolved. The ambiguity-free and ambiguity-fixed results for kinematic and reduced-dynamic POD are compared with the K-band measurements (KBR). The best POD approaches show an agreement on the level of 3 mm with KBR, which is an improvement by a factor of about 7 compared to the zero-difference and ambiguity-free cases, where both satellites are estimated independently. Since the signals received by a LEO GPS receiver are not affected by tropospheric refraction, the GRACE GPS baseline in combination with the K-band is suitable to study the impact of higher-order terms of the ionospheric refraction, use of signal-to-noise ratio and the effects of GPS receiver antenna patterns on LEO POD.
DE: 1227 Planetary geodesy and gravity (5420, 5714, 6019)
DE: 1229 Reference systems
DE: 1241 Satellite orbits
SC: Special Focus: Advances in Data Acquisition, Management, Analysis and Display [SF]
MN: 2004 AGU Fall Meeting