MINI-ASTROD: MISSION CONCEPT AND STUDY PROGRESS

The success of lunar laser ranging, the proposition of gravitational-wave detection in space using laser-interferometric techniques, together with a couple of mission proposals to test relativistic gravity using optical methods triggered the proposition of a systematic development of Laser Astrodynamics in the solar system in 1993. In this context, ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) mission concept was proposed. Mini-ASTROD is a down-scaled version of ASTROD. This mission concept has one spacecraft carrying a payload of a telescope, two (plus two spare) lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme and yet give important scientific results. These scientific goals include a better measurement of the relativistic parameters (γ, β to 10-7 and others with improvement), a better sensitivity (several times better) in using optical Doppler tracking method for detecting gravitational waves, a potential of measuring the solar angular momentum via Lense-Thirring effect and measurement of many solar system parameters more precisely. These will enable us to build a more precise ephemeris and astrodynamics. The weight of this spacecraft is estimated to be about 300-350 kg with a payload of about 100-120 kg. The present orbit option is to launch with an initial period about 290 days and to pass by Venus twice to receive gravity-assistance for achieving shorter periods. In this paper, we review the scientific goals and the mission scheme, and present the current study progress.