June 16, 2015, Update: 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, according to the U.S. Strategic Command’s Joint Functional Component Command for Space through the Joint Space Operations Center (JSpOC). The U.S. Space Surveillance Network, operated by the Defense Department's JSpOC, had been closely monitoring TRMM’s descent since the mission was ended in April. Most of the spacecraft was expected to burn up in the atmosphere during its uncontrolled re-entry. Learn more.

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Frequently Asked Questions: TRMM Spacecraft Re-Entry

The Tropical Rainfall Measuring Mission (TRMM), a joint mission of NASA and the Japan Aerospace Exploration Agency, was launched in 1997 to study rainfall for weather and climate research. After over 17 years of productive data gathering, the instruments on TRMM were turned off on April 8 and the spacecraft will slowly descend from its orbit.

When will the TRMM spacecraft re-enter the atmosphere and burn up?

The spacecraft is estimated to reenter the atmosphere and largely burn up in mid-June 2015. It is not possible to predict in advance the exact time when re-entry will occur.

What risks are there to people and property from falling pieces of TRMM?

There is a very low risk to people and property from pieces of TRMM that reach Earth’s surface. Most of the spacecraft will burn up in the atmosphere during re-entry. Of the spacecraft's total mass (about 5,800 lbs.), 96 percent will never reach Earth. The chance that a piece of the spacecraft will strike a person is approximately 1 in 4,200.

Where will any remains of TRMM likely reach Earth's surface?

TRMM circles the Earth between the subtropical latitudes of both the northern and southern hemispheres. Due to natural variations in the near-Earth environment, a precise location of where spacecraft debris will re-enter cannot be forecast. The U.S. Space Surveillance Network, operated by the Department of Defense U.S. Strategic Command’s Joint Space Operations Center, will closely monitor the orbit of TRMM debris during its final days and issue periodic predictions of re-entry time and location.

How many NASA satellites, launch vehicles, and other large orbital debris re-enter Earth's atmosphere each year?

In recent years the number has been about half a dozen.

How many of these re-entries have resulted in confirmed personal injury or major property damage?

Since the beginning of the space age in the 1950s, there has been no confirmed report of an injury resulting from re-entering space objects.

Will some of the TRMM spacecraft remain in orbit to contribute to orbital debris?

No. After the TRMM spacecraft has re-entered, there will not be any components remaining on orbit to contribute to orbital debris.

When was the last time that a NASA science satellite re-entered Earth's atmosphere?

The Upper Atmosphere Research Satellite (UARS) re-entered in September 2011. UARS was a much larger satellite than TRMM – the size of a bus rather than an SUV. NASA received no reports of debris.

Who should be called if someone suspects they found space debris?

They should call their local authorities. The pieces of TRMM expected to survive re-entry are made of titanium or stainless steel.  Although these materials are not toxic, they could have sharp edges and should not be touched or handled by private individuals.

NASA Office of Communications
J.D. Harrington
j.d.harrington@nasa.gov