Living Planet   


The GRACE Mission: Status and Relevance to GOCE

Prof. Byron Tapley(1)and Prof Christoph Reigber(2)

(1) University of Texas, 3925 W. Braker Ln., Austin, United States
(2) GeoForschungZentrum Potsdam, Telegrafenberg A 17, D-14473 Potsdam, Germany


The Gravity Recovery and Climate Experiment (GRACE) is a dedicated satellite mission whose objective is to map the global gravity field with unprecedented accuracy over a spectral range from 500 km to 40,000 km. The measurement precision will support gravity field solutions in this frequency range that are between 10 and 1000 times better than our current knowledge. The mission profile calls for a gravity field solution with this accuracy every thirty days. Accurate measurements, with both high spatial and temporal resolution, will allow capture the gravitational signals associated with the mass exchange between the Earths solid, ocean and atmospheric system components. The primary measurement provided by the High Accuracy Inter-satellite Ranging System (HAIRS) is the range change between two satellites orbiting one behind the other at an approximate distance of 220 km. The range change is measured with a precision better than 10 microns over a ten second averaging interval. A highly accurate three-axis accelerometer, located at the satellite mass center, will be used to measure the surface force and attitude control induced accelerations. Satellite GPS receivers will position the satellites over the earth with centimeter level accuracy. The two satellites were launched on March 17, 2002 and were designed to operate for a period of five years.

This presentation will review the mission status and describe the status of the early science results, including the efforts to identify the time varying signal. Finall, the contributions to oceanography and hydrology Finally, the presentation will highlight possible contributions of the Grace Mission to the GOCE Mission objectives.


Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry