Engineers found out earlier this year that Kepler was almost out of fuel. They put it into safe mode then so they could use the remaining fuel wisely by receiving all the data Kepler had already gathered. After a while, they managed to turn it on again and gather more scientific data, knowing that soon it would be time to bid farewell to the Kepler space telescope.
When launched, it was expected to last only six years, but it managed to outlive its designed lifespan by three years. Now that it’s out of fuel, NASA decided to officially retire the spacecraft, letting it float in a safe orbit far from Earth. Some time next week, the engineers will send a command to turn off the spacecraft’s transmitter and other instruments and leave it to orbit.
Kepler was launched in 2009 with a mission of discovering worlds outside our own solar system, also known as exoplanets. At first, scientists didn’t discover many exoplanets, but in just a short time, Kepler discovered thousands of exoplanets.
“When we started conceiving this mission 35 years ago, we didn’t know of a single planet outside our solar system,” Kepler’s founding principal investigator, William Borucki (now retired), said in a press release. “Now that we know planets are everywhere, Kepler has set us on a new course that’s full of promise for future generations to explore our galaxy.”
During the first years of Kepler’s operations, the telescope was extremely successful. However, in 2012 its equipment malfunctioned. The situation got even worse the next year, and engineers feared they would need to bid farewell to the Kepler space telescope then. However, a solution arose in 2013, when scientists decided to use the pressure of sunlight to balance the spacecraft, keeping it steady for 83 days at a time. NASA then started a new mission called K2.
K2 enabled researchers to discover many planets, concluding that planets are extremely common. The two Kepler missions discovered and confirmed the existence of 2,681 planets in all.
All the data Kepler collected has now been safely returned to Earth. Several other exoplanet-hunting missions are expected to start in the future, including one using the James Webb Space Telescope, which will succeed both the Kepler and the Hubble Space Telescope.
Earlier this year, NASA launched the Transiting Exoplanet Survey Satellite (TESS), so it won’t run out of options to search for new planets. Still, TESS has a long way to go before it catches up to the success of Kepler’s mission.
This is not the final goodbye to Kepler though. Scientists have yet to analyze all the received data.
“We know the spacecraft’s retirement isn’t the end of Kepler’s discoveries,” Kepler Project Scientist Jessie Dotson said. “I’m excited about the diverse discoveries that are yet to come from our data and how future missions will build upon Kepler’s results.”