Momo-1(MOS-1), Japan's first marine observation satellite, was launched in 1987 as a link in a global satellite observation system for more effective natural resource utilization and for environmental protection.

Momo-1 was equipped with three types of sensors: MESSR,( a spectrometer for measuring visible near infrared radiation), VTIR, (a device for measuring visible thermal infrared radiation), MSR, (for measuring microwave radiation).These sensors finished their roles of sending waves on November 29, 1995.

Momo-1b(MOS-1b), which has the same functions as Momo-1, was launched subsequently as a follow-up and finished its operation on April 17,1996.