A joint space mission between NASA and the Japan Aerospace Exploration Agency (JAXA), within the Earth Science Enterprise programme of the European Space Agency, that was launched on 27 November 1997 from the Tanegashima Space Center, Japan, into a near-circular, low-inclination orbit at a height of 350 km, inclined at 35° to the equator. It carries five instruments: precipitation radar (PR), TRMM microwave imager (TMI), visible and infrared scanner (VIRS), clouds and the Earth’s radiant energy systems (CERES), and lightning imaging sensor (LIS). The mission measures diurnal variations in tropical precipitation and evaporation.

http://global.jaxa.jp/projects/sat/trmm/ About Tropical Rainfall Measuring Mission.