Over time, that kind of information will allow forecasters to improve the models they use, says Skofronick Jackson. It also will let scientists studying climate change calibrate satellite-radiometer data collected as early as the 1970s to find long-term trends in precipitation patterns, she says.

JAXA and NASA engineers here are overseeing the environmental test sequence on the 3,200-kg (7,055-lb.) spacecraft. If all goes as planned, it should be ready to launch in February 2014, according to Art Azarbarzin, GPM project manager here.

However, that is being carried as an internal launch date, with a 50% confidence level, he says. NASA has promised Congress it will be able to launch the spacecraft by June 2014, an 11-month slip that was forced by the devastating earthquake that hit Japan in March 2011, damaging test facilities at JAXA's Tsukuba City site north of Tokyo, just as the two large Japanese radars were being tested. Debris from test-chamber walls contaminated the clean test environment, Azarbarzin says, and the loss of power prevented maintenance of proper temperature and humidity levels. As a result, the DPR had to be cleaned and retested before it could be shipped to Goddard for integration into the satellite.

The spacecraft also suffered from normal development delays in Japan and the U.S., including a problem perfecting the coating on the reflector for the GMI that Goddard engineers solved with a new vendor.

NASA's portion of the mission is capped at $932.8 million, including reserves. In addition to JAXA, other agencies participating in the effort by sharing their radiometer data are French space agency CNES and the Indian Space Research Organization, with their joint Meghatropiques mission; the U.S. National Oceanic and Atmospheric Administration; Europe's Eumetsat and the U.S. Defense Department through its Defense Meteorological Satellite Program.

Nine U.S. and international satellites will soon be united by the GPM mission, a partnership co-led by NASA and JAXA. To watch an animation of the constellation in action, check out the digital edition of AW&ST on leading tablets and smartphones, or go to AviationWeek.com/video