Nasa's new space observatory, the Transiting Exoplanet Survey Satellite, or Tess, has already taken up the search for planets in the nearby cosmos, and giant telescopes both on the ground and in space are being created to detect and observe exoplanets - planets that circle stars outside our solar system.
Watch to find out about its incredible journey.
Four years into the mission, after the primary mission objectives had been met, some mechanical failures temporarily halted observations. "It was an extremely clever approach to doing this kind of science", said Leslie Livesay, director for astronomy and physics at NASA's Jet Propulsion Laboratory, who served as Kepler project manager during mission development.
The space telescope was nearly lost in 2013 when Kepler had a failure, but engineers found a way to fix it and help the mission carry on until this month. Originally only created to operate for around three and a half years, the spacecraft ultimately spent over nine and a half years in operation. This second phase of Kepler's science program was called the K2 mission. They and Kepler are old spacecraft far beyond their design lifetimes. Thanks in part to its groundbreaking camera, Kepler was able to broaden that search and locate smaller, rockier planets much more similar to Earth.
Borucki, who dreamed up the mission decades ago, said one of his favorite discoveries was Kepler 22b, a water planet bigger than Earth but in an area where it is not too warm and not too cold - the type "that could lead to life".
Before retiring the spacecraft, scientists pushed Kepler to its full potential, successfully completing multiple observation campaigns and downloading valuable science data even after initial warnings of low fuel.
And those discoveries have helped shape future missions. TESS, the Transiting Exoplanet Survey Satellite, launched in April and is the newest planet hunter for NASA.
Kepler's retirement marks just the beginning of a quest to end humankind's cosmic loneliness.
Now that it has no fuel, the telescope can't correct its very specific orbit, so it is drifting farther and farther from our planet. And in 2017 "Kepler" found "assosolare system" of the eight planets just like ours (after Pluto was demoted and transferred to the category of dwarf planets).
"While this may be a sad event, we are by no means unhappy with the performance of this marvellous machine", NASA project system engineer Charlie Sobeck said. Recently, the MAST archive team won a NASA Group award for their work in hosting the Kepler data sets.
When launched, it was expected to last only six years, but it managed to outlive its designed lifespan by three years.
The Kepler space telescope launched from Earth on March 6, 2009. "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".