Nasa’s Kepler space telescope has run out of fuel and ended its mission to discover planets around other stars.
Launched in 2009, Kepler observed 530,506 stars and discovered more than 2600 confirmed planets. Kepler has also identified thousands more possible planets that are pending further investigation.
The mission was first conceived 35 years ago and detected planets by looking for the way a star’s light dims when a planet crosses the star’s face.
Originally designed to look for Earth-like planets in the habitable zone of stars like the sun, Kepler instead found a rich diversity of planets around many different types of stars. Red dwarf stars, which are smaller and cooler than the sun, provided rich pickings.
Many of the planets Kepler found around these stars are potentially habitable, yet have years that last only a few days. Mechanical failures ended the most precise phase of Kepler’s observations four years after launch but engineers and astronomers devised a way to continue searching for planets using the spacecraft.
Kepler is succeeded by the Transiting Exoplanet Survey Satellite (Tess), which Nasa launched in April. The European Space Agency is currently testing the CHaracterising ExOPlanet Satellite (Cheops), which will accurately measure the density of planets around other stars to determine if they are rocky planets like Earth.