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MOS

Space-based oceanography is conducted in Japan by two Marine Observation Satellites (MOS) placed in sun-synchronous orbits of approximately 910 km with an inclination of 99.1 degrees. After 10 years of development MOS 1 (aka Momo 1 or "Peach tree") was launched in February, 1987, and was followed by MOS 1b (Momo 1b) in February, 1990, into an orbital plane only a few degrees away from MOS 1. The program objectives include:

• "a Development of observation sensors; verification of their functions and performances, and experimental observation of the Earth (in particular the oceans) using such sensors;
• Basic experiments on a data collection system (DCS);
• Establishment of fundamental technologies for Earth observation satellites" (Reference 583).

Funded and managed by NASDA, the MOS program selected NEC Corporation as the prime contractor with significant assistance by Mitsubishi Electric, Toshiba, and Fujitsu. Each 740-kg, 3-axis-stabilized spacecraft consists of a box-shape bus (1.3 m by 1.5 m by 2.4 m) with a single solar array (2.0 m by 4.5 m). The selected orbit permits a repeating groundtrack with a period of 17 days.

The MOS payload consists of four primary classes of instruments. Two 70-kg Multi-spectral Electronic Self-Scanning Radio-meters (MESSR) return images in four bands (0.51-0.59 µm, 0.61-0.69 µm, 0.72-0.80 µm, and 0.80-1.1 µm) with a ground resolution of 50 m and a swath of 100 km. The fields-of-view of the two MESSR sensors are slightly overlapped (15 km) to provide stereo viewing. The 25-kg Visible and Thermal Infrared Radiometer (VTIR) operates in one visible and three IR bands: 0.5-0.7,µm, 6-7 µm, 10.5-11.5 µm, and 11.5-12.5 µm with ground resolutions of 900 m (visible) and 2,700 m (JR) and a swath of 1,500 km. The 54 kg Microwave Scanning Radiometer (MSR) is tuned to two frequencies: 23.8 GHz and 31.4 GHz. The swath is 317 km with respective resolutions of 23 km and 32 km. Finally, the Data Collection System Transponder (DCST) collects data from DCP's transmitting in the 400 MHz band and relays the information to data acquisition and processing facilities at a frequency of 1.7 GHz. MESSR and VTIR data are transmitted at 1.7 GHz and 8 GHz, while MSR data are downlinked at 2 GHz. MOS 1 and MOS 1b are expected to remain operational until about 1997 and 2001-2002, respectively (References 583-585).

REFERENCES

583. "Japan's New Space Bid", Spaceflight, April, 1987, p. 138-141.

584. NASDA. National Space Development Agency of Japan, NASDA, 1992, pp. 21-22.

585. N. W. Davis, "Japan Stresses Multisatellite Remote Sensing", Aerospace America, March 1993, p. 28.

Sources and Resources

• Adapted from: Europe and Asia in Space 1993-1994, Nicholas Johnson and David Rodvold [Kaman Sciences / Air Force Phillips Laboratory]

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