NASA‘s great planet hunter, the Kepler Space Telescope, is running out of fuel. The end is near. NASA announced Friday that it is made the decision to put it into an “hibernation-like state”, so it can rest until it can send one last data haul home. And, after a long and wonderful run, we all need to say a proper goodbye with respect and admiration.
Kepler has been in space for more than 9 years. It launched in March, 2009 on its first mission to find how common Earth-like ‘exoplanets’ are in the Milky Way. It stared at around 150,000 stars simultaneously, using the transit system (looking for dips in the light from stars that would suggest a planet in their orbits). Thanks to Kepler, it is thought that “about 20 percent of sunlike stars host a roughly Earth-size planet in the habitable zone — that just-right range of distances where liquid water could exist on a world’s surface.” That’s according to space.com.
When two of Kepler’s “orientation-maintaining reaction wheels” failed in 2013, engineers figured out how to stabilize the telescope using sunlight pressure, and Kepler went on its extended mission (K2) in 2014. According to nasa.gov, as of May, 2018, Kepler had found 2,650 confirmed exoplanets. That number will go up after the mission ends. Scientists are still vetting more than 2,000 planet candidates, and more will come with the last data set.
On August 2nd, “during its allotted Deep Space Network time” Kepler will be activated, maneuvered to a position where its antenna is pointed back to Earth, and downlink the data. If it has any fuel left after that, it will attempt another campaign. But, its curtains for the telescope. It can’t be refueled, as it’s millions of miles from home, orbiting the sun. The TESS will take up the planet hunting mantle, and Kepler will become another skeleton in the sky. R.I.P., Kepler.