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Space


Geostationary Meteorological Satellite (GMS)

The Japanese geostationary satellite is a crucial element in forecasting and warning of typhoon development and subsequent flooding. The Japanese Geostationary Meteorological Satellite (GMS) series, also known as its nickname, "Himawari" (meaning a "sunflower"), is on the geostationary orbit at 140 degrees of east longitude to carry out weather observation from space being part of the World Weather Watch (WWW) project of the World Meteorological Organization. The images of the earth and clouds sent from this satellite series have been used in many areas such as weather forecasts in TV or newspaper.

Japan's Geostationary Meteorological Satellite (GMS) system was originally developed by NASDA relying heavily on the US GOES design and is now jointly run by NASDA and the Japan Meteorological Agency. The American firm Hughes was the prime contractor, working for Japan's NEC Corporation.

Himawari 1 was launched 1977-07-14 by a Delta in the US, the others flown from Japans own Tanegashima Space Center. The Geostationary Meteorological Satellite (GMS) was Japan's contribution to the international GARP (Global Atmospheric Research Program). One major objective of GARP was to obtain synoptic global meteorological data sets for 1 year's duration (to include two optimized observing periods of a few weeks each). These data served as raw material to optimize computer models for meteorological prediction. It was hoped that determination could be made of the time limitation for short-term modeling. This spacecraft was roughly cylindrical with a height of 345 cm and a diameter of 216 cm. The cylindrical surface was covered with solar cells which could provide 225 W. The satellite was spin-stabilized with a despun earth-pointing antenna. The satellite was positioned near 140 deg E. Designed to operate for 5 years, the satellite was turned off in 1981 after 4 1/2 years in orbit.

The GMS-2 was launched from NASDA's Tanegashima Space Center in Kagoshima Prefecture, Japan at 05:03 (JST). GMS-2 was launched in August 1981, and was operational in December that year in place of GMS. GMS-2 was roughly cylindrical with a height of 345 cm and a diameter of 216 cm. The cylindrical surface was covered with solar cells which provided 225 W. The satellite was spin-stabilized with a despun earth-pointing antenna. The satellite was positioned near 140 deg E and was designed to operate for 5 years. This was a follow-on GMS type spacecraft launched and controlled by NASDA of Japan. The spacecraft was turned off in September 1984. The satellite was positioned near 140 deg E and was designed to operate for 5 years. This was a follow-on GMS type spacecraft launched and controlled by NASDA of Japan.

GMS-3, launched 1984-08-02, was spin-stabilized with a despun earth-pointing antenna. The satellite was positioned near 140 deg E and was designed to operate for 5 years. This was a follow-on GMS type spacecraft launched and controlled by NASDA of Japan.

GMS-4 was a spin-stabilized (100 rpm) spacecraft with an on-orbit mass of approximately 325 kg, a diameter of 2.1 m and a height (after apogee kick motor separation) of 3.4 m (Figure 4.69). Solar cells applied to the exterior of the spacecraft bus generate up to 300 W. and the overall design life is five years. Hydrazine thrusters maintain the desired geostationary position and counteract perturbations attempting to alter the vehicle's inclination.

The major Earth-oriented instrument is the Visible and Infrared Spin Scan Radiometer (VISSR), "used to obtain visible and infrared spectrum mappings of the Earth and its cloud cover with a specially designed optical telescope and detector system" (Reference 581). Visible images are collected in the 0.50-0.75 µm band with a resolution of 1.25 km, and the infrared signatures are taken in the 10.5-12.5, µm band with a 5.0-km resolution. Thirty minutes are required to obtain a full Earth image consisting of 2,500 narrow strips. A separate payload, called the Space Environment Monitor (SEM), measures the flux of solar protons, alpha particles, and electrons.

While outwardly almost identical to GMS-4, GMS-5 hosted a more sophisticated VISSR with one visible band (0.55-0.9 µm) and three IR bands (10.5-11.5, µm, 11.5-12.5 µm, and 6.5-7.0 µm). The relative visible and IR resolution will remain unchanged. The height of the spacecraft will increase slightly to 3.5 m as will the on-orbit mass of 338 kg. In place of the SEM, an experimental COSPAS-SARSAT transponder was carried (Reference 582).

GMS 5 was a Japanese geostationary meteorological spacecraft launched 1995-03-18. It replaced GMS 4 (1989-070A) and was initially parked at 140 E longitude. It carried visible and infrared spin-scan radiometers that provided global pictures every 25 minutes at a resolution of 1.25 km (visible) and 5.0 km (infrared). It also had an infrared channel to monitor water vapor content in the atmosphere. Other instruments on board were for search-and-rescue relays and for relaying weather data from ground/sea-based monitoring platforms. The spacecraft had a stabilized earth pointing platform and a 100 rpm spinning section. The spacecraft had a diameter of 215 cm and a height of 354 cm.

After the "Himawari-5", the GMS series was replaced by a Multifunctional Transport Satellite series to broaden its scope of operation. It is operated by the Japan Meteorological Agency for climatic observation. GMS 5 was to be deactivated once MTSAT was operational. The November 15, 1999 launch of MTSAT on an H-2 rocket ended in failure when the rocket veered off course. GMS 5 is at the end of its five-year design lifetime in mid-2000. However, operations were extended by employing procedures to save on fuel used for station-keeping. As of June 2003, GOES-9 had replaced Japan's GMS 5. MTSAT-1RA, the replacement for GMS 5, was planned for launch in 2004.

After the "Himawari-6", the GMS series was replaced by a Multifunctional Transport Satellite series to broaden its scope of operation. It is operated by the Japan Meteorological Agency for climatic observation.

Improvement of channels

GMS GMS-2 GMS-3 GMS-4 GMS-5 MTSAT-1R MTSAT-2 Himawari-8 Himawari-9
Channel
and
Wavelength
Visible (0.50-0.70 m) Visible (0.55-0.90 m) Visible (0.46 m)
Visible(0.51 m)
Visible(0.64 m)
Near Infrared (0.86 m)
Near Infrared (1.6 m)
Near Infrared (2.3 m)
IR4 (3.5-4.0 m) IR (3.9 m)
IR (6.2 m)
IR (7.0 m)
IR (7.3 m)
IR (8.6 m)
IR (9.6 m)
IR (10.4 m)
IR (11.2 m)
IR (12.3 m)
IR (13.3 m)
IR3 (6.5-7.0 m)
(Water vapor)
IR (Infrared)
(10.5-12.5 m)
IR1
(10.5-11.5 m)
IR1
(10.3-11.3 m)
IR2 (11.5-12.5 m)




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Page last modified: 04-08-2015 21:39:54 ZULU