MOS-1b, also known as Momo-1b, was a follow-up mission to the original MOS-1 (Marine Observation Satellite-1). Launched by Japan on February 7, 1990, MOS-1b continued the objectives set by its predecessor to monitor the Earth's environment and gather valuable data for various applications.

Similar to MOS-1, the primary mission of MOS-1b was to observe and monitor the Earth's environment. It aimed to provide data for applications in oceanography, agriculture, forestry, disaster management, and environmental monitoring.