LunarStar Subsatellite "GAUSS" - A Proposal for the Complete Gravity Field Determination of the Moon

Abstract

GAUSS will be provided by Germany as a contribution to LUNARSTAR Mission in the NASA Discovery program. The main scientific objectives of the LUNASTAR mission are the exploration of a lunar atmosphere, the study of lunar geochemistry and the surface evolution of the Moon In connection with a determination of the total gravity field with high resolution (typically 70 - 70), considerable new insight will be gained in the following areas: Global shape model of the Moon, near/far-side dichotomy, structure and evolution of large impact craters and basins, evolution of the lithosphere, comparative planetology. It is proposed to provide a subsatellite with a total mass of ~ 16 kg dedicated only to gravity field determination. GAUSS shall relay phase coherent microwave signals (S-band) from LUNARSTAR to Earth with an overall Doppler accuracy of better than 1 mm/s. The frequency source (USO) onboard the Lunastar main spacecraft. From the Doppler data collected at the German and US groundstations both local and global gravity information will be derived. The time duration for the gravimetry mapping part of the LUNARSTAR has reached its 100 km altitude polar circular orbit. GAUSS will remain in the eccentric polar lunar transfer orbit (200 km - 5000 km). Launch is forseen in October 2001.