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. Re-entry was originally expected sometime between May 2016 and November 2017, but occurred sooner due to heightened solar activity. The probe's primary sensor, the precipitation radar, was switched off for the final time on 1 April 2015 and the final scientific sensor, LIS, was turned off on 15 April 2015. Re-entry occurred on 16 June 2015 at 06:54 UTC.