NASA is about to turn off the Kepler spacecraft, and it will drift away

Enlarge / NASA's planet-hunting Kepler spacecraft has run out of fuel. (credit: NASA)

After more than nine years in operation, the Kepler Space Telescope has run out of hydrazine fuel. Mission managers will now send a command to the spacecraft, which is presently trailing Earth in a heliocentric orbit about 150 million kilometers away, to turn off the spacecraft's transmitters. It will be cast adrift into the silent blackness of space.

But though the spacecraft's effective mission will end, it will live on in troves of data that scientists have yet to process. Already, during its lifetime, the spacecraft has found 2,681 confirmed planets and an additional 2,899 candidate planets that require follow-up confirmation from ground-based telescopes. Those numbers were current as of Monday evening.

Kepler can safely be counted as one of the most transformative missions that NASA has ever sent into space. Prior to its launch, astronomers knew planets existed around other stars, but their knowledge beyond that was fuzzy. Now, astronomers have a wealth of information. "Because of Kepler, what we think about our place in the universe has changed," Paul Hertz, Astrophysics Division director at NASA Headquarters, said Tuesday during a conference call with reporters.