Kepler forced into retirement

Since March 2009, the Kepler space telescope has scanned the Universe, searching for evidence of distant, undiscovered worlds. By measuring tiny dips in light caused by objects orbiting in front of faraway stars, Kepler has identified 135 confirmed planets to date, with thousands more waiting to be verified. The changes in light are minute, and detecting them needs a steady gaze – something that Kepler can no longer manage since two of its four stabilisation wheels stopped functioning properly. These wheels point the telescope in a particular direction and hold it there, and their malfunction makes it impossible for Kepler to continue its mission accurately.

Of the planets identified by Kepler and other similar space telescopes, it is the handful of Earth-like planets that have most excited astronomers searching for signs of extraterrestrial life. Because Earth is the only place in the Universe known to support life, finding similar planets (in terms of size, orbit and composition) is considered the best bet for discovering it elsewhere. So far the search has come up empty-handed, but with plenty of data still to be analysed, Kepler will continue to assist the planet-hunters’ quest for some time to come. Earlier this year, scientists used Kepler’s findings to estimate the number of Earth-sized planets in the Milky Way at 17 billion – meaning there’s plenty of work left to do!

Unfortunately, that work will have to continue without the hobbled Kepler – though there just might be life in the telescope yet. NASA is currently considering whether it is economically worthwhile to reconfigure the retired satellite and use its instruments to monitor other astronomical features, such as comets or asteroids. Until then, Kepler will remain in orbit around our Sun, awaiting further instructions.