The Grace Mission: The Challenges of Using Micron-Level Satellite-to-Satellite Ranging to Measure the Earth's Gravity Field

The GRACE Mission, to be launched in mid-2001, will provide an unprecedented map of the Earth's gravity field every month. In this paper, we outline the challenges associated with this micron-level satellite-to-satellite ranging, the solutions used by the GRACE project, and the expected science applications of the data.