Ume 2

The ISS (Ionosphere Sounding Satellite) series of satellites was Japan's first ionosphere sounding satellite project. After reaching orbit, they were named Ume. ISS b or Ume 2 was put into orbit two years later as a replacement. Ume-2 kept gathering observation data even after its 1.5 year mission term. It finished its operation on 23 February 1983, because of deterioration of power generation.