Kepler was a space telescope designed to survey a portion of the Milky Way galaxy in search of exoplanets, which are planets outside our solar system.
Using data from the Kepler mission and the extended K2 mission, scientists have identified more than 2,800 candidate exoplanets and have confirmed more than 2,600 of these as bona fide planets. A handful of planets are thought to be rocky like Earth (but a bit bigger), and orbit in the habitable zone of their stars, where liquid water - an essential ingredient of life as we know it - might exist.
In 2013, Kepler was assigned a new mission called "K2." Two of the spacecraft's reaction wheels had failed, so engineers came up with a clever scheme to redesign the mission. K2 still hunted for planets, but it scanned a larger swath of sky than before, along the ecliptic plane. The mission began new types of research as well, such as the study of objects within our solar system, exploded stars, and distant supermassive black holes at the hearts of galaxies.
After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets - more planets even than stars - NASA's Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.
October 30, 2018 - End of Mission (ran out of fuel)
More than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.