The Gravity Recovery and Interior Laboratory Mission (GRAIL) is the 11thmission of the NASA Discovery Program. Its objective is to help answer fundamentalquestions about the Moon's internal structure, thermal evolution, andcollisional history. GRAIL employs twin spacecraft, which fly in formation inlow altitude polar orbits around the Moon. An improved global lunar gravityfield is derived from high-precision range-rate measurements of the distancebetween the two spacecraft. The purpose of this paper is to describe the strategiesused by the GRAIL Orbit Determination Team to overcome challengesposed during on-orbit operations.
展开▼
