Kepler blows its top April 9, 2009Posted by CosmicThespian in Space Missions.
Kepler is a space mission to search for extrasolar planets by looking for periodic transits – the dimming of a star’s light as an orbiting planet occasionally passes between the star and observers on Earth. Launched on March 7 aboard a Delta II rocket, the telescope will trail behind the Earth on a heliocentric (Sun-centered) orbit for 3.5 years. During its mission, the telescope will stare at the same patch of sky in the constellation Cygnus, monitoring 100,000 stars for the occasional transit of a planetary companion. The instrument is designed to be able to detect Earth-sized planets orbiting on Earth-like orbits around distant stars! Project scientists estimate that over its lifetime, Kepler could discover around 50 Earth-like worlds in this region of the Galaxy and many hundreds of other types of planets. A new age of exoplanet discovery is about to begin!
This is the type of science that can only be done from space. Planetary transits last for only a few hours and may only occur once or a few times a year. To maximize detection, one needs to stare at the same stars for several years. This simply can’t be done from Earth. Earth-bound observers can not use their telescope during the day and most areas of the sky are unavailable to us for large portions of the year as the Earth travels around the Sun. Plus, the change in brightness of a star due to the transit of an Earth-like world is very tiny; roughly one part in 10,000! To be able to definitively detect such a miniscule dip in brightness, we need a telescope that sits above the interference of the Earth’s atmosphere where turbulence and other meteorological effects can either mask the signal or produce false detections. In space we don’t have to worry about day and night or deal with the atmosphere. We can just stare!
Yesterday, the Kepler space mission achieved an important milestone. The telescope cover was released from the instrument and light has begun to fall onto the electronic detectors that will capture the images. Now begins the several week long process of calibrating the instrument by using images of stars before actual science operations can begin. The dust cover is now drifting away from Kepler on its own orbit around the Sun. From the JPL press release:
“The cover released and flew away exactly as we designed it to do,” said Kepler Project Manager James Fanson of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “This is a critical step toward answering a question that has come down to us across 100 generations of human history — are there other planets like Earth, or are we alone in the galaxy?”
An animation of the dust cover release can be found here.