[3] Development of the satellite became a joint project between the space agencies of the United States and Japan, with Japan providing the Precipitation Radar (PR) and H-II launch vehicle, and the United States providing the satellite bus and remaining instruments.

TRMM is a joint project between the United States and Japan to measure rainfall between 35.0° North and 35.0° South at 350 km altitude.

[7] In 2005, NASA director Michael Griffin decided to extend the mission again by using the propellant originally intended for a controlled descent.

[8] Battery issues began to limit the spacecraft in 2014 and the mission operations team had to make decisions about how to ration power.

[7] In July 2014, with propellant on TRMM running low, NASA decided to cease station-keeping maneuvers and allow the spacecraft's orbit to slowly decay, while continuing to collect data.

The remaining fuel, initially reserved to avoid collisions with other satellites or space debris, was depleted in early March 2015.

[10] The Precipitation Radar (PR) was the first space-borne instrument designed to provide three-dimensional maps of storm structure.

It is based on the design of the highly successful Special Sensor Microwave/Imager (SSM/I) which has been flying continuously on Defense Meteorological Satellites since 1987.

The Visible and Infrared Scanner (VIRS) was one of the three instruments in the rain-measuring package and serves as a very indirect indicator of rainfall.

VIRS, as its name implies, sensed radiation coming up from the Earth in five spectral regions, ranging from visible to infrared, or 0.63 to 12 mm.

It only operated during January–August 1998, and in March 2000, so the available data record is quite brief (although later CERES instruments were flown on other missions such as the Earth Observing System (EOS) AM (Terra) and PM (Aqua) satellites.)

The imager's field of view allowed the sensor to observe a point on the Earth or a cloud for 80 seconds, a sufficient time to estimate the flashing rate, which told researchers whether a storm was growing or decaying.