After staring into the far reaches of our galaxy and beyond for nine years, space telescope Kepler was finally decommissioned by NASA on October 30, 2018 after expending all fuel reserves. Kepler’s primary function was to search for exoplanets of all kinds overall. However, the potential other Earth-like worlds discovered made most of the headlines, and understandably so. It launched on March 6, 2009 aboard United Launch Alliance’s Delta II rocket from Cape Canaveral Air Force Station in Florida, and its mission ended around 94 million miles away from us in an “Earth trailing” orbit around the sun.
Some of Kepler’s accomplishments during its time online included the mind-blowing discovery that there are more planets in our night sky than stars. According to the telescope’s mission page run by NASA, Kepler also taught us about the diversity of other solar systems and planets, and that up to 50% of observable stars in our sky likely have rocky, Earth-sized planets surrounding them. NASA additionally maintains both an Exoplanet Archive and Exoplanet Exploration page providing details on all Kepler’s discoveries to date and artistic interpretations of some of the most exciting finds.
One of the more recently famous Kepler discoveries that you may have heard of is “Tabby’s Star”. After volunteers classifying images on the site PlanetHunters.org noticed strange behavior in its light patterns, theories around the behavior’s cause bubbled up all over the Internet. Some even speculated that the observations would align with the existence of an alien energy-gathering megastructure called a “Dyson Sphere” (or Stapledon sphere, if you’re a sci-fi buff). Further study has revealed dust to be the most likely culprit, but the momentary excitement was in line with some of the telescope’s original inspiration: Are we alone?
Kepler may be gone, but the search for other worlds both like and unlike ours carries on. The Transiting Exoplanet Survey Satellite (TESS), launched into space on April 18, 2018, will continue studying planets around the brightest stars as seen from Earth. Scientists anticipate the catalog of confirmed exoplanet discoveries (Kepler’s currently numbering over 2,000) to expand by the hundreds very quickly as TESS begins its two-year mission, and a quick review of its progress confirms the likelihood of that prediction.