Since December 1997, TRMM and the instruments it carries have provided valuable information to researchers, the applications community, and the public. On July 8, 2014, pressure readings from the fuel tank indicated that TRMM is at the end of its fuel. As a result, NASA has ceased station keeping maneuvers and TRMM has begun its drift downward from its operating altitude of 402 km. A small amount of fuel has been retained to conduct debris avoidance maneuvers to ensure the satellite remains safe during the drift down.
TRMM observations will continue as the spacecraft descends to 335 km, at which time it will be shutdown prior to re-entry. This date is nominally estimated to be February 2016, but may change depending on solar activity. While TMI and LIS will continue operating during the entire drift down period, the TMI data will be affected. TMI incidence angle will be changing as will the field of view. However, we expect useful data to continue especially for non-climate research.
JAXA has indicated that they may soon stop distribution of the radar data since useful science data is only possible within narrow altitude ranges near 400 and 350 km. When TRMM reaches 350 km (its original altitude), radar data may resume for a short period.