The first spacecraft dedicated to finding potentially habitable planets beyond our solar system is poised to blast off from Cape Canaveral tonight on a three-year mission to probe 150,000 stars in the most sweeping hunt for Earthlike objects ever undertaken by NASA.
By the end of the Kepler mission, scientists will probably know whether planets like ours -- where liquid water can exist on the surface to nurture life -- are common in the universe, or so rare that we are virtually alone in the cosmic sea.
For The Record
Los Angeles Times Tuesday, March 10, 2009 Home Edition Main News Part A Page 4 National Desk 1 inches; 30 words Type of Material: Correction
Kepler spacecraft: An article in Friday's Section A about NASA's Kepler spacecraft said lead mission scientist Bill Borucki was affiliated with UC Berkeley. He works for NASA's Ames Research Center.
"This is not just another science mission," said NASA Associate Administrator Ed Weiler in a news briefing at the space agency's headquarters in Washington. "If you ask me, are there other Earths out there, I'd say absolutely. But I can't prove it."
"We certainly won't find E.T.," added Bill Borucki, the lead mission scientist from UC Berkeley, "but we might find E.T.'s home."
The $590-million Kepler mission, scheduled to lift off at 7:49 p.m. Pacific time, consists of the widest-field telescope ever flown by NASA. The nearly 15-foot-long instrument has a 55-inch-wide mirror that can simultaneously scrutinize thousands of stars in its search for extrasolar planets, or exoplanets. It will accomplish this by looking for periodic dimming -- or winking -- of a star's light caused by planets crossing in front of it, which scientists refer to as a transit.
Many of the 340 or so known exoplanets, principally discovered by a team in Europe and another at UC Berkeley headed by well-known planet hunter Geoff Marcy, have been found using the same method.
But most of those planets are gas giants, like Jupiter, that orbit very close to their parent stars. Those planets would be far too hot to sustain life, even if they had a rocky surface.
No potentially habitable planet has been found outside our solar system.
Finding one by using ground-based telescopes has been extremely difficult because of atmospheric interference. Even the Hubble Space Telescope, which has a larger mirror, falls short because its field of view is too narrow. It's designed to look deeply rather than widely.
The Kepler spacecraft -- named after 17th century German astronomer Johannes Kepler, who discovered the laws of planetary motion -- will be able to scan a region of the northern sky between the constellations Cygnus and Lyra that contains about 4.5 million stars. Of the total, according to mission scientist Natalie Batalha of San Jose State University, 150,000 stars have been selected for intense study.
