The MOS 1A and 1B satellites, also known as Momo 1A and 1B, were Japan's first Earth resources satellites. The satellites were designed to monitor ocean currents, sea surface temperature, atmospheric water vapour, ocean chlorophyll levels, precipitation, and land vegetation. They also acted as relays for data from remote surface sensor platforms. MOS 1B was upgraded for flight from the engineering model for MOS 1A. Spacecraft: 3-axis stabilised with momentum wheels, hydrazine thrusters. Nadir pointing. S-, X-band downlink, S-band uplink. Single solar panel with 1-axis articulation. Payload: Multispectral Electronic Self-Scanning Radiometer (MESSR) - covers 4 bands between 0.51 and 1.1 micron, 50 m resolution, 200 km swath. Designed to observe ice distribution, land use, snow cover, ocean chlorophyll. Visible and Thermal Infrared Radiometer (VTIR) - covers 6 bands between 0.5 and 12.5 microns, 0.9 - 2.7 km resolution, 1500 km swath. Designed to monitor snow, cloud, ice coverage, sea surface temperatures. Microwave Scanning Radiometer (MSR) - 2 frequency radiometer (23.8, 31.4 GHz) with 23-32 km resolution, 317 km swath. Monitors atmospheric water vapour content, snowfall, and rainfall.

Design Life: 2 years. Total Length: 2.4 m. Maximum Diameter: 1.5 m. Total Mass: 742 kg.

Ocean remote sensing. MOS-1 (Momo-1). Observation of marine phenomena such as sea color and temperature. Establishment of common technology necessary for Earth observation satellites. Launching organization NASDA. Launch time 0123 GMT.

Marine observation. Continuation of Earth observation functions of MOS-1; establishment of common technology necessary for Earth-observation satellites. Launching organization NASDA. Name MOS-1b 'Momo-1b'. Launch time 0133 UT.

• 2 - McDowell, Jonathan, The United Nations Registry of Space Objects, Harvard University, 1997. HTML when accessed: http://hea-www.harvard.edu/QEDT/jcm/space/un/un.html
• 6 - JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. HTML when accessed: http://msl.jpl.nasa.gov/home.html
• 279 - McDowell, Jonathan, Launch Log, October 1998. HTML when accessed: http://hea-www.harvard.edu/~jcm/space/log/launch.html