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Tropical Rainfall Measuring Mission spacecraft falls to Earth

Visualization of the TRMM satellite in space over a tropical cyclone. Image Credit: NASA

Visualization of the TRMM satellite in space over a tropical cyclone. Image Credit: NASA

A satellite, built jointly by NASA and the Japan Aerospace Exploration Agency (JAXA ) to measure the amount of rainfall on Earth, has ended its long-lasting mission in a fiery demise. According to the U.S. Strategic Command’s Joint Functional Component Command for Space, the Tropical Rainfall Measuring Mission (TRMM ) spacecraft re-entered the Earth’s atmosphere on June 15, 2015, at 11:55 p.m. EDT, over the South Indian Ocean.

Most of the spacecraft burned up in the atmosphere during its uncontrolled re-entry. NASA estimates that 12 components of the TRMM spacecraft could have survived re-entry. These objects included two propellant tanks, a nitrogen pressurant tank, four Reaction Wheel Assembly (RWA) flywheels, two Solar Array Drive Assembly (SADA) actuators, a High Gain Antenna (HGA) boom bracket, a HGA antenna bracket, and a TRMM Microwave Imager (TMI) Bearing and Power Transfer Assembly (BAPTA) housing and shaft. Surviving objects are metallic (titanium alloys) and are not toxic.

“Any sightings of suspected TRMM debris should be reported to local authorities,” NASA said in a statement. “Debris could have sharp edges and should not be touched or handled, in the unlikely event someone were to find TRMM fragments.”

NASA has stated that the chances of one of these pieces striking someone is approximately 1 in 4,200. The total mass of objects expected to survive is estimated to be approximately 247 lbs. (112 kg).

NASA, conferring with the U.S. Government and some foreign space agencies, has reduced that risk from re-entering space objects even more – to less than 1 in 10,000.

TRMM is a moderate-sized satellite. Uncontrolled re-entries of objects more massive than TRMM are not frequent, nor are they all that unusual. However, since the beginning of the Space Age, there has been no confirmed report of an injury resulting from re-entering space objects.

The U.S. Space Surveillance Network, operated by the Defense Department’s Joint Space Operations Center (JSpOC), had been closely monitoring TRMM’s descent since the mission was ended in April.

TRMM was a research satellite designed to improve our understanding of the distribution and variability of precipitation within the tropics as part of the water cycle in the current climate system.

The satellite was launched on a Mitsubishi H-II rocket from Japan’s Tanegashima spaceport in 1997 on a planned three-year mission, but managed to be fully operational for 17 years. In 2001, the mission was extended until 2005, when residual propellant would reach the minimum required for controlled re-entry from 249 miles (400 km) altitude.

After considerable analysis and review, TRMM was relieved of the controlled re-entry requirement to prolong its mission until the Global Precipitation Measurement (GPM) spacecraft could be launched (then predicted to be 2010, actually launched in February 2014).

NASA ceased station-keeping maneuvers of TRMM near the end of the spacecraft’s fuel supply in July 2014. The instruments on the satellite were finally turned off on April 8, 2015, and the spacecraft slowly descended from its orbit.

“The TRMM dataset will continue to be used for research to improve global weather and climate models. The data meet exacting standards for data preservation, so that future scientists will be able to use the data. The dataset also is being processed to make up one continuous climate data record with the follow-on GPM, also a joint project between the U.S. and Japan,” NASA said.



Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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