Deep-space laser-ranging missions ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I for astrodynamics and astrometry

Abstract

Deep-space laser ranging will be ideal for testing relativistic gravity, and mapping the solar-system to an unprecedented accuracy. ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I are such missions. ASTROD I is a mission with a single spacecraft; it is the first step of ASTROD with 3 spacecraft. In this talk, after a brief review of ASTROD and ASTROD I, we concentrate of the precision of solar astrodynamics that can be achieved together with implications on astrometry and reference frame transformations. The precision planetary ephemeris derived from these missions together with second post-Newtonian test of relativistic gravity will serve as a foundation for future precise astrometry observations. Relativistic frameworks are discussed from these considerations.