Precise Determination of the Baseline Between the TerraSAR-X and TanDEM-X Satellites
Abstract
TerraSAR-X, launched on June 15, 2007, and TanDEM-X, to be launched in September 2009, both carry the Tracking, Occultation and Ranging (TOR) category A payload instrument package. The TOR consists of a high-precision dual-frequency GPS receiver, called Integrated GPS Occultation Receiver (IGOR), for precise orbit determination and atmospheric sounding and a Laser retro-reflector (LRR) serving as target for the global Satellite Laser Ranging (SLR) ground station network. The TOR is supplied by the GeoForschungsZentrum Potsdam (GFZ) Germany, and the Center for Space Research (CSR), Austin, Texas. The objective of the German/US collaboration is twofold: provision of atmospheric profiles for use in numerical weather predictions and climate studies from the occultation data and precision SAR data processing based on precise orbits and atmospheric products. For the scientific objectives of the TanDEM- X mission, i.e., bi-static SAR together with TerraSAR-X, the dual-frequency GPS receiver is of vital importance for the millimeter level determination of the baseline or distance between the two spacecrafts. The paper discusses the feasibility of generating millimeter baselines by the example of GRACE, where for validation the distance between the two GRACE satellites is directly available from the micrometer-level intersatellite link measurements. The distance of the GRACE satellites is some 200 km, the distance of the TerraSAR-X/TanDEM-X formation will be some 200 meters. Therefore the proposed approach is then subject to a simulation of the foreseen TerraSAR-X/TanDEM-X formation. The effect of varying space environmental conditions, of possible phase center variations, multi path, and of varying center of mass of the spacecrafts are evaluated and discussed.
- Publication:
-
37th COSPAR Scientific Assembly
- Pub Date:
- 2008
- Bibcode:
- 2008cosp...37.1562K