TRMM Satellite Out of Station-keeping Fuel

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.

Core Observatory Commissioning Continues

The Global Precipitation Measurement mission's Core Observatory commissioning activities continued normally this week. Both the GPM Microwave Imager and the Dual-frequency Precipitation Radar (DPR) are collecting science data and NASA and the Japan Aerospace Exploration Agency released the first images from the instruments on March 25.

The DPR's functional checkout activities and internal calibration continued. The first external calibration using the Active Radar Calibration site in Tsukuba, Japan, was performed on March 23. 

GPM Performs Yaw Turn, Continues Calibration

On March 17, the team executed GPM's first scheduled yaw turn to turn the orientation of the spacecraft 180 degrees. Yaw is the left/right orientation in the horizontal plane of the spacecraft's motion. The spacecraft is now "flying backwards." Yaw maneuvers will be performed approximately every 40 days for spacecraft thermal control, as the angle between the spacecraft's orbit and the sun changes. This keeps the side of the spacecraft that is designed to remain cold from overheating. Yaw maneuvers are performed primarily using the spacecraft's reaction wheels.

Global Precipitation Measurement Constellation

Nine U.S. and international satellites will soon be united by the Global Precipitation Measurement (GPM) mission, a partnership co-led by NASA and the Japan Aerospace Exploration Agency (JAXA). NASA and JAXA will provide the GPM Core satellite to serve as a reference for precipitation measurements made by this constellation of satellites, which will be combined into a single global dataset continually refreshed every three hours.

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