Super Low Altitude Test Satellite
SLATS, the Super Low Altitude Test Satellite, is a JAXA satellite intended to demonstrate operations in very low Earth orbit (below 200 km), using ion engines to cancel out aerodynamic drag and equipped with sensors to determine atomic oxygen density, an exposure facility to measure material degradation in the 200 km orbit, and a small camera. Initial designs had conventional, though slightly canted, solar panels (compare to the aerodynamic shape and on-body solar panels of GOCE, which flew in a 255 km orbit).
SLATS will be launched on a H-IIA rocket alongside the GCOM-C satellite to a 630 km orbit, followed by orbit-lowering manoeuvres by a combination of chemical propulsion and aerobraking, with final operation at an altitude below 180 km. The launch is to take place on early 2017. As of December 2015, the satellite is manifested for 'FY2016 or later' on JAXA's launch schedule page.