Spaceborne superconducting sounder ( SMILES-2 ) for upper-atmosphere observation

The Superconducting Submillimeter-Wave LimbEmission Sounder 2 (SMILES-2) is a proposed satellite mission for the comprehensive observation of Earth’s atmosphere with superconducting receivers. The SMILES-2 mission will have four SIS/HEB receivers with bands near 487, 527 GHz, 557, 576 GHz, 623, 653 GHz, and 1.8, 2 THz to observe spectral lines of atomic oxygen, OH, O3, O2, H2O, CO, NO, NO2, N2O, ClO, HCl, and BrO. The atmospheric limb will be scanned in an altitude range from 20 km to more than 160 km in a minute or shorter time. The low-noise superconducting receivers will provide highly qualified limb spectra of a variety of atmospheric species, from which we can retrieve temperature and wind over the whole altitude range encompassing the stratosphere, mesosphere, and lower thermosphere. The global temperature and wind profiles of the whole atmosphere measured by a single instrument will be the most scientifically useful data for studying the lower and upper atmosphere coupling. The wind precision of SMILES-2 measurement is estimated to be better than 3 m/s with an altitude resolution of 3 km in the upper stratosphere and mesosphere, and 10 m/s with an altitude resolution of 5 km in the lower thermosphere. We are now studying the feasible design of the mission to be boarded on a Japanese small satellite.