TRMM is the joint project of Japan and U.S. Japan is responsible for developing one of the onboard observation instruments, the Precipitation Radar (PR), and launching the satellite by H-II launch vehicle. Since the launch, the observation has been continued for more than 6 years, exceeding the initially planned nominal observation period of 3 years. TRMM has succeeded to collect huge valuable observation data, including meteorological phenomenon over land and sea, and the global hydrological cycle.

In last October, NASA, who is responsible for TRMM operation, proposed to terminate TRMM operation and to perform safe ocean disposal of the satellite through controlled re-entry as soon as possible. This proposal was due to the safety concern about the continuation of the operation of the satellite which has far exceeded its design life. JAXA asked NASA to study the possibility of continuing TRMM observation within the safety limitation, and has worked with NASA to find a solution of continuing the operation. However, today, JAXA has reached to the conclusion to agree to NASA's proposal.

It is expected that TRMM will terminate its observation operation during July, followed by the altitude lowering drift down phase. Controlled re-entry and safe ocean disposal will be completed about a year later.

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