UME-2 (ISS-b) was the second ionosphere satellite named after Ume. The satellite was designed for monitoring radio waves in the ionosphere and forecast conditions for optimal use of shortwave communications. UME-2 was put into orbit two years later - a power supply system failure caused Ume to malfunction one month after launching.

UME-2 kept gathering observation data even after its 1.5 year mission term. The operations were ended on February 23, 1983 because of deterioration of power generation.