Tropical Rainfall Measuring Mission
Artist conception of the TRMM satellite
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| Mission type | Environmental research |
|---|---|
| Operator | JAXA / NASA |
| COSPAR ID | 1997-074A |
| SATCAT no. | 25063 |
| Spacecraft properties | |
| Launch mass | 3524 kg |
| Dry mass | 2634 kg |
| Power | 1100 W |
| Start of mission | |
| Launch date | 27 November 1997 |
| Rocket | H-II |
| Launch site | Tanegashima Space Center |
| End of mission | |
| Deactivated | 9 April 2015 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | LEO |
| Eccentricity | 0.0001344 |
| Perigee | 174 kilometers (108 mi) |
| Apogee | 176 kilometers (109 mi) |
| Inclination | 34.9372° |
| Period | 92.5 minutes |
| RAAN | 203.9770 degrees |
| Argument of perigee | 140.8634 degrees |
| Mean anomaly | 219.2792 degrees |
| Mean motion | 16.36482121 |
| Epoch | 15 June 2015 at 18:20:01 UTC |
The Tropical Rainfall Measuring Mission (TRMM) was a joint space mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall. The term refers to both the mission itself and the satellite that the mission used to collect data. TRMM was part of NASA's Mission to Planet Earth, a long-term, coordinated research effort to study the Earth as a global system. The satellite was launched on November 27, 1997 from the Tanegashima Space Center in Tanegashima, Japan.
As of July 2014, fuel to maintain orbital altitude was insufficient and NASA ceased station-keeping maneuvers for TRMM, allowing the spacecraft's orbit to slowly decay. Re-entry was originally expected sometime between May 2016 and November 2017. The probe was turned off on April 9, 2015 after its orbital decay accelerated. Re-entry occurred on June 16, 2015 at 06:54 UTC.
Tropical precipitation is a difficult parameter to measure, due to large spatial and temporal variations. However, understanding tropical precipitation is important for weather and climate prediction, as this precipitation contains three-fourths of the energy that drives atmospheric wind circulation. Prior to TRMM, the distribution of rainfall worldwide was known to only a 50% degree of uncertainty.
The concept for TRMM was first proposed in 1984. The science objectives, as first proposed, were:
Japan joined the initial study for the TRMM mission in 1986. Development of the satellite became a joint project between the space agencies of the U.S. and Japan, with Japan providing the Precipitation Radar (PR) and H-II launch vehicle, and the U.S. providing the satellite bus and remaining instruments. The project received formal support from the U.S. congress in 1991, followed by spacecraft construction from 1993 through 1997. TRMM launched from Tanegashima Space Center on 27 November 1997.
The Precipitation Radar was the first space-borne instrument designed to provide three-dimensional maps of storm structure. The measurements yielded information on the intensity and distribution of the rain, on the rain type, on the storm depth and on the height at which the snow melts into rain. The estimates of the heat released into the atmosphere at different heights based on these measurements can be used to improve models of the global atmospheric circulation. The PR operated at 13.8 GHz and measured the 3-d rainfall distribution over land and ocean surfaces. It defined a layer depth of perception and hence measured rainfall that actually reached the latent heat of atmosphere. It had a 4.3 km resolution at radii with 220 km swath.
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