Properties of SELENE Small Satellites for Selenodetic Measurements: Rstar (OKINA) and Vstar (OUNA)

Abstract

SELENE Main Orbiter (KAGUYA) has separated two small sub-satellite (1) the Relay Satellite “Rstar (OKINA)”, and (2) the VLBI Radio Satellite “Vstar (OUNA)”. These sub-satellites started to perform 4-way Doppler measurements using Relay Satellite Transponder (RSAT) and multi frequency differential VLBI using VLBI Radio Sources (VRAD) for selenodesy. Initial check out was executed and properties of satellite bus equipments, onboard mission instruments, and observation systems including ground stations were evaluated. Electric power and thermal control subsystems have shown that they conduct as designed and inspected in the ground tests. The release mechanisms have given the spin which can maintain the stability of the satellite attitudes. Communication functions of mission instruments conform to the link budgets. These results suggest that Rstar and Vstar have enough performances to produce efficient selenodetic data by RSAT/VRAD observations.