On March 7, 2009, NASA launched the Kepler space telescope into orbit around the Sun. Outside the Earth’s atmosphere, it would be free to peer deeply into a cross-section of our galaxy in search of new planets orbiting other stars.
After nine years in action covering two separate mission phases (designated as Kepler and K2), the Kepler space telescope finally ran out of fuel and was forced to cease operations in October 2018. But over the course of its lifespan, it discovered more than 2,600 new planets, at least a few of which may be capable of supporting life.
In addition to the 2,681 objects already classified as exoplanets (planets outside the solar system), the U.S. space agency listed another 2,899 candidates for planetary status that have yet to be verified, and a positive result is expected for most. As of 2015, the data from the initial Kepler mission (K2 data was not yet available) had confirmed the existence of 30-50 Earth-sized planets known to be orbiting inside their star’s “habitable zone,” which means temperatures would allow for the existence of water on the surface.
“As NASA’s first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond.”
These were the words of Thomas Zurbuchen, the associate administrator of NASA’s Science Mission Directorate in Washington, marking the occasion of Kepler’s official retirement from active duty.