<h2>AAS 99-144</h2>
<h2>Simulation of the Gravity Recovery and Climate Experiment (GRACE) Mission                                                                        </h2>
<h4>J-R. Kim, P. Roesset, S. Bettadpur, B. Tapley                                                                                                                                       </h4>
The University of Texas, Austin                                                                                                                                           
<h2> Abstract </h2>
The Gravity Recovery and Climatic Experiment (GRACE) is a dedicated spaceborne mission to map the gravity field with unprecedented accuracy. The satellites are planned to launch planed in 2001 over a lifetime of approximately 5years. It consists of two satellites, co-orbiting in nearly polar orbit, at approximately 300-500 km altitude, separated by 100-500 km along track. Primary measurements are the range change between two satellites, which are combined with the accelerometer, GPS and laser tracking measurements. After description of the mission and simulation procedure, we will describe the results of the numerical simulation studies in progress,