[PEM10-P09] SMILES-2 mission, conceptual design for applying to ISAS M-class mission
Keywords:satellite observation, middle atmosphere, limb observation, wind observation, atomic oxygen, submillimeter-wave
SMILES-2 is equipped with superconducting receivers at bands of 638 GHz, 763 GHz, and 2 THz. Comparing to the JEM/SMILES receiver, higher frequency and wider bandwidth are used for SMILES-2. The band of 638 GHz is used with JEM/SMILES but will be wider bandwidth of 8 GHz for SMILES-2 than that of JEM/SMILES, that is 2 GHz. The receiver at 2 THz for observation of atomic oxygen and OH uses a newly developed hot-electron bolometer (HEB) mixer. A cryocooler system to cool the superconducting devices to about 4 K will be a similar configuration with that of JEM/SMILES, but an improved system, that is having a longer life time which has been demonstrated with a ground test experiment. A concern of using cryocooled superconducting receivers on SMILES-2 is limitation of available power of small size (M-class) satellite. With the SMILES-2 orbit, that is 550 km altitude and 66 degree inclination, the ratio of time length of sun shade to the orbit period reaches 37 %. This large sun shade ratio increases the power demand during the sun shinning period because large current is required to charge batteries. The available power for the SMILES-2 mission instrument can be estimated to be less than 323 W on the assumption that a realistic electic power system of the small size satellite bus is used. We are seeking a feasible system design that consists of a cryocooler system consuming a power of 282 W and other mission instruments consuming 41 W. SMILES-2 is one of the space science mission concept submitted to the opportunity for JAXA/ISAS M-class missions which is planned to launch in 2024 and 2026.