NASA revealed on Saturday, July 7, that the Kepler Space Telescope is almost out of fuel and that the space agency decided to put the spacecraft in a hibernation-like state.

Kepler's Fuel Running Very Low

NASA said that the Kepler team was notified that the fuel tank of Kepler is running very low. The planet-hunting spacecraft was placed into hibernation safe mode past Monday to prepare for the downloading of the science data collected during the observatory's latest observation campaign.

NASA expects that observations for the next campaign can start with the remaining fuel once the science data has been downloaded.

Top Priority For The Remaining Fuel

Kepler has been on its 18th observation campaign since May 12 collecting data from the part of the sky towards the constellation of Cancer that it earlier studied in 2015. Astronomers hope that the latest data will provide them with a chance to confirm previous exoplanet candidates and find new ones. Returning these data back to Earth is the highest priority for the remaining fuel of the spacecraft.

Deep Space Network Time

Transmitting back these data requires the spacecraft to point its large antenna back to Earth during the allotted Deep Space Network time set in early August. Until this time, Kepler will remain stable and parked in a no-fuel-use safe mode.

The Kepler team will wake up the spacecraft on August 2 and maneuver it to the correct orientation to downlink the data. The team will start its 19th observation campaign on August 6 if the download is successful.

Mission Expected To End Soon

NASA already expects that the mission is coming to an end soon as the spacecraft runs low in fuel. Given the amount of fuel Kepler had during launch and estimates on how much of this has been used over the past nine years, NASA determined that the spacecraft's fuel supplies would run out this year.

"With nary a gas station to be found in deep space, the spacecraft is going to run out of fuel. We expect to reach that moment within several months," Charlie Sobeck, system engineer for the Kepler space telescope mission said in March. "Our current estimates are that Kepler's tank will run dry within several months."

Kepler's Successor

NASA has already launched Kepler's successor, the Transiting Exoplanet Survey Satellite, or TESS, which will also hunt for exoplanets. The spacecraft is designed to find Earth-sized planets that orbit within the "habitable zone" of stars.