It’s finally happening. NASA has announced that its Kepler telescope may have seen its last exoplanet, as the spacecraft has now all but run out of fuel.
In a statement, NASA said its Kepler telescope would end its latest hunt for exoplanets, and use its remaining fuel to send its science data back to Earth. If fuel levels are as low as thought, this means Kepler's hunt for planets will end.
“NASA’s Kepler team has received data showing that the spacecraft’s ability to point precisely has degraded,” the agency said. “In order to preserve high-value science data collected during its latest observation campaign, the Kepler team has placed the spacecraft in a stable, no-fuel-use sleep mode.”
Kepler was observing planets beyond our Solar System as part of its Observation Campaign 19, which began on August 29. For 27 days it observed thousands of stars, looking for dips in light as planets passed in front, known as the transit method.
A small number of these stars were already known to have exoplanets, including the TRAPPIST-1 system, which contains seven Earth-sized planets. However, the bulk of the stars were those that weren’t known to have planets.
With the telescope running out of fuel, NASA is eager to get as much data from it as possible. Positioned 150 million kilometers (93 million miles) from Earth, Kepler needs fuel to point itself back to our planet and send data our way. Without fuel, it can no longer do this.
Kepler will send this data back to Earth between October 10 and 15, with the telescope being kept in safe mode until then. But this might not be the end of the mission entirely – if the spacecraft successfully sends back all its data, NASA will try to find new planets as part of Observation Campaign 20.
Even if it can no longer look at planets, there will be plenty more discoveries to come from Kepler. Scientists will still need to pore through its data, which will take years, with many more planets expected to be found.
But if the telescope can no longer point itself towards other stars, this will mean this latest batch from Campaign 19 contains the last planets Kepler will ever see. And that’s a huge loss for exoplanet science.
Kepler has almost single-handedly ignited the field of exoplanet science. Since it launched in 2009 it has found more than 2,600 worlds beyond our Solar System, the vast majority of exoplanets we have discovered.
NASA launched a new planet hunter, the Transiting Exoplanet Survey Satellite (TESS), earlier this year to take over the reins. But the loss of Kepler will bring an end to a pivotal chapter in the history of finding new worlds. So long, and thanks for all the planets.