January 2, 2007
(PLANETQUEST) -- The first space-based mission designed to search for planets around other stars was successfully launched on December 27.
The CoRoT (Convection, Rotation and planetary Transits) mission, led by the French national space agency, is expected to significantly increase the total number of known extrasolar planets. It will provide the first detections of rocky planets, perhaps just a few times the mass of Earth.
Over its 2.5-year mission, CoRoT will monitor tens of thousands (60,000) of stars with its 30-centimeter primary mirror and an array of charge-coupled devices, searching for planetary transits. A transit occurs when an orbiting planet crosses the face of a star, causing a slight dip in brightness.
The rocky planets the mission can find will be located close to their parent stars - closer than Venus - and too hot to support life. But CoRoT will help lay the groundwork for future missions specifically designed to search for habitable planets, including NASA's SIM PlanetQuest and Terrestrial Planet Finder.
"The key result of CoRoT will be a better estimate of the frequency of planets of a few times the size of the Earth," said Dr. Chas Beichman, executive director of Caltech's Michelson Science Center. "It will be a big confidence-builder."
Dr. Jean Schneider, a senior researcher at the Paris Observatory, notes that CoRoT will open new vistas of knowledge in a relatively young field.
"In addition to detecting tens of transiting hot Jupiters (compared to 18 known today), we should be able to detect and measure the size of the first super-Earths," Schneider said in an e-mail interview. He defines a super-Earth as a planet about twice as large as the Earth. "We will also be able to detect and measure, for the first time, moons and rings of exoplanets."
Schneider, who first proposed the search for planets with CoRoT in the late 1980s, is also the originator of the Extrasolar Planets Encyclopedia, a well-known professional website that tracks and catalogs new planet discoveries (http://exoplanet.eu/). When the site was launched before the discovery of the first extrasolar planet in February 1995, Schneider said, he had little inkling that the field would expand so rapidly.
"There were a few encouraging signs ... but at that time we were also in a complete fog; we had no idea if exoplanets were exceptional or common."
Now, Schneider's website lists extensive data for more than 200 planets beyond our sun, and new discoveries are posted regularly.
Successors to this European mission include NASA's Kepler mission, scheduled for launch in 2008. With a 0.95-meter mirror, Kepler will work the same way as CoRoT, looking for planetary transits. Kepler is expected to find the first potentially habitable planets in orbits similar to Earth.
In addition to its planet-search program, CoRoT will provide a window into stellar evolution by observing subtle variations in starlight caused by sound waves rippling across the surfaces of many different types of stars. The study of these stellar "seismic waves" will give scientists detailed insight into the internal conditions of stars.
CoRoT was developed in partnership with the European Space Agency, Austria, Spain, Germany and Brazil. The spacecraft was launched aboard a Soyuz spacecraft from the Baikonur cosmodrome in Kazakhstan.
Written by Randal Jackson/PlanetQuest
