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About MOS-1/1B

MOS-1 satellite. Credit: JAXA

The MOS (Marine Observation Satellite) Constellation, made up of MOS-1 and 1B, were Japan’s first marine observation satellites, owned and operated by the National Space Development Agency of Japan (NASDA), now JAXA (Japan Aerospace Exploration Agency). MOS-1 and 1B were launched in February 1987 and February 1990, and completed operations in November 1995 and April 1996, respectively.

Mission parameters
Launch Date19 February 19877 February 1990
End Date29 November 199517 April 1996
Orbit Type909 km909 km
Orbit Period103 min103 min
Repeat Cycle17 days17 days

MOS-1/1B Objectives

MOS-1 and 1B, Japan’s first marine observation 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.


MESSR (Multi-spectral Electronic Self-Scanning Radiometer)

MESSR was a four-band pushbroom radiometer, with two visible (VIS) spectral bands and two near-infrared (NIR) bands, with a 50 m Ground Sample Distance (GSD) and a swath width of 100 km. For increased reliability of data, two copies of MESSR were onboard the spacecraft, each with swath widths of 100 km, yielding a combined swath width of 200 km. The instrument could achieve global coverage in 17 days.

MESSR Instrument Characteristics
Spectral Band1 (VIS)2 (VIS)3 (VIS)4 (NIR)
Wavelength Range (nm)510 – 690610 – 690720 – 800800 – 1100
Spatial Resolution (m)50505050
Swath Width (km)100100100100


MSR (Microwave Scanning Radiometer)

MSR was a passive microwave radiometer with two channels operating at respective frequencies of 24 GHz and 31 GHz, and corresponding ground resolutions of 32 km and 23 km, providing global coverage in 5 days.

MSR Instrument Characteristics
Frequency (GHz)23.831.4
Spatial Resolution (km)3223
Swath Width (km)317317


VTIR (Visible and Thermal Infrared Radiometer)

VTIR was a mechanical-scanning radiometer with a visible (VIS) spectral band, and three thermal infrared (TIR) bands. The instrument scanned cross-track swaths 1500 km wide, with along-track scans provided by the motion of the spacecraft. VTIR had a ground resolution of 0.9 km for the VIS band with daily global coverage, and 2.7 km for the TIR bands with global coverage in 2 days.

MESSR Instrument Characteristics
Spectral Band1 (VIS)2 (TIR)3 (TIR)4 (TIR)
Wavelength Range (nm)0.5 – 0.76.0 – 7.010.5 – 11.511.5 – 12.5
Spatial Resolution (m)
Swath Width (km)1500150015001500