Momo-1, also known as MOS-1 (Marine Observation Satellite-1), was Japan's first Earth observation satellite. Launched by the National Space Development Agency of Japan (NASDA) on February 19, 1987, MOS-1 was part of Japan's effort to develop its space technology and capabilities in satellite-based Earth observation.

The primary mission of MOS-1 was to monitor the Earth's environment and provide data for various applications, including oceanography, agriculture, forestry, and disaster management.