Goodbye to TRMM, Japan's first rain radar in space

Artist concept of TRMM in space over the eye of a tropical cyclone. 

Credit: NASA

After 17 years of groundbreaking 3-D images of rain and storms, the joint NASA and JAXA (Japan Aerospace Exploration Agency) Tropical Rainfall Measuring Mission (TRMM) will come to an end next year.

NASA predicts that science operations will cease in or about April 2015, based on the most recent analysis by mission operations at NASA's Goddard Space Flight Center, Greenbelt, Maryland.

On July 8, 2014, pressure readings from the fuel tank indicated that TRMM was near the end of its fuel supply.

As a result, NASA ceased station-keeping maneuvers that would keep the satellite at its operating altitude of 402 km (249.8 miles).

Atmospheric drag is slowing TRMM, and it has begun its slow drift downward. Some fuel has been retained to conduct debris avoidance maneuvers to ensure the satellite remains safe during the drift down to re-entry, which is predicted to occur in the summer of 2015.

Originally launched in 1997 as a three-year mission, TRMM's extended mission life has provided a boon to the scientific understanding of precipitation and its role in broad weather patterns and climate.

TRMM has allowed scientists to better understand how rain varies daily, seasonally and annually; how El Niño affects global rain patterns; how regional rain events like the Indian monsoon vary throughout the season; and even how humans have affected local precipitation through the effects of urban heat islands, deforestation and pollution.

"TRMM has been the world's foremost satellite for the study of precipitation and climate processes in the tropics, and an invaluable resource for tropical cyclone research and operations," says TRMM Project Scientist Scott Braun at NASA Goddard.

"Data from TRMM will continue to foster science well after the mission ends, and, when combined with data from the new Global Precipitation Measurement Core Observatory (GPM), launched earlier this year by NASA's partner the Japan Aerospace Exploration Agency (JAXA), will contribute to a long-term precipitation climate record."

This 3-D image of Hurricane Sandy's rainfall was created using TRMM Precipitation Radar data. 

It shows the storm as it appeared on Oct. 28, 2012. 

Credit: NASA /SSAI, Hal Pierce

Orbiting at an angle to the equator that covers 35 degrees north to 35 degrees south of the equator, TRMM carries five instruments that collectively measure the intensity of rainfall, characteristics of the water vapour and clouds, and lightning associated with the rain events.

One of the instruments, the Precipitation Radar, built by JAXA, is the first precipitation radar flown in space.

It returns images of storms that for the first time have revealed close-up, 3-D views of how rain bands in tropical cyclones develop, potentially indicating how strong the storms might become.