SMILES-2 is a proposed spaceborne mission using THz superconducting receiver for measurement of the Earth's atmospheric thermal limb emission. The mission concept is prepared for the call-for-proposals for JAXA/ISAS M-class scientific satellite mission. SMILES-2 will measure wind, temperature, atmospheric compositions in the stratosphere, mesosphere and lower thermosphere, and their diurnal cycles. Three-band receiver at 638 GHz, 763 GHz, and 2 THz can cover the unprecedented wide altitude range of wind and temperature observation. A technical concern of the mission is a large power consumption requirement to the resource of an M-class satellite orbiting a non-sun-synchronous orbit. Large power is necessary to operate cryocooler for cooling superconducting devices that work at temperature of around 4 K. We are studying measures to reduce the power consumption and enhance the feasibility of the mission.