Submillimeter Limb-emission Sounder JEM/SMILES aboard the Space Station

摘要

A submillimeter limb-emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as "KIBO") at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb-emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gases by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator-Superconductor (SIS) mixer, which is operated at 4.5K in a dedicated cryostat combined with a mechanical cooler. SMITES will observe ozone-depletion-related molecules such as ClO, HCl, HO_2, HNO_3, BrO and O_3 in the frequency bands at 624.32-626.32GHz and 649.12-650.32GHz. A scanning antenna will cover tangent altitudes from 10 to 60km in every 53 seconds, while tracing the latitudes from 38S to 65N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid-latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2GHz with a resolution of 1.8MHz. This high-resolution spectroscopy will allow us to detect weak emission lines attributing to less-abundant species.