tation and planetary T
ransits) is a space mission led by the French Space Agency (CNES)
in conjunction with the European Space Agency (ESA)
and other international partners. The mission has two objectives: to search for extrasolar planets
with short orbital periods, particularly those of large terrestrial size
, and to perform asteroseismology
by measuring solar-like oscillations
in stars. It was launched at 14:28 GMT
on December 27
, atop a Soyuz 2.1b
carrier rocket. COROT subsequently reported first light
on January 18
It is the first mission of its kind. It detected its first extrasolar planet, COROT-Exo-1b
, in May 2007.
COROT consists of a 27 cm (10.6 inch) diameter afocal telescope
with an array of spectroscopic
detectors. The satellite, built in the Cannes Mandelieu Space Center
, has a launch mass of 630 kg, is 4.10 metres long, 1.984 metres in diameter and is powered by two solar panels . A Russian Soyuz 2-1B
rocket lifted the satellite into a circular polar orbit
with an altitude of 827 km on 27 December 2006
. The first scientific observation campaign started on February 3 2007
Over its planned 2½ year mission it will observe perpendicular to its orbital plane, meaning there will be no Earth occultations, allowing 150 days of continuous observation. During the northern summer it will observe in an area around Serpens Cauda and during the winter it will observe in Monoceros. During the remaining 30 days between the two main observation periods, COROT will observe 5 other patches of sky.
The probe will monitor the brightness of stars, watching for the slight dimming that happens in regular intervals when planets transit their primary sun. COROT will be sensitive enough to detect rocky planets several times larger than Earth; it is also expected to discover new gas giants, which currently comprise almost all of the known extrasolar planets.
COROT will also undertake asteroseismology. It can detect luminosity variations associated with acoustic pulsations of stars. This phenomenon allows calculation of a star's precise mass, age and chemical composition and will aid in comparisons between the sun and other stars.
In each field of view there will be one main target star for the asteroseismology as well as up to nine other targets. Simultaneously, it will be recording the brightness of 12,000 stars brighter than apparent magnitude 15.5 for the extrasolar planet study. It is expected that a few dozen planets will be found as a result of this project.
The primary contractor for the construction of the COROT vehicle was CNES
, to which individual components were delivered for vehicle assembly. The COROT equipment bay, which houses the data acquisition and pre-processing electronics, was constructed by the LESIA Laboratory at the Paris Observatory
and took 60 man-years
to complete. The COROT camera, also constructed by the LESIA Laboratory, took 25 person-years to complete.
Before the beginning of the mission, the team stated with caution that COROT would only be able to detect planets a few times to several times larger than Earth and that it was not specifically designed to detect habitable planets
(it would instead assess their potential for habitability). According to the press release announcing the first results, COROT's instruments are performing with higher precision than had been predicted, and may be able to find planets down to the size of Earth.
COROT should be assumed to only detect a small percentage of planets within its detection range due to the low percentage of existing planets that would likely make transits from the angle of observation from our Solar System. Expectations are that any planetary systems detected within a suitable range for further observations will be followed up by the future Darwin and Terrestrial Planet Finder spacecrafts or other projects like Kepler (NASA), New Worlds Mission, or Space Interferometry Mission.
On May 3, 2007, it was reported that COROT had discovered a 'hot Jupiter
orbiting a sun-like star 1,500 light years away. This planet has a radius approximately 1.78 times that of Jupiter
, a mass approximately 1.3 times that of Jupiter, and orbits its parent star once every 1.5 days. On the 300th day of operations ESA reported that "CoRoT is discovering exo-planets at a rate only set by the available resources to follow up the detections". On December 20, 2007, additional results were published, declaring that a second exoplanet, COROT-Exo-2b
had been discovered, this time with a radius 1.4 times and a mass 3.5 times that of Jupiter
. The orbital period is less than two days. Results on asteroseismology
were published in the same press release. Three papers describing the two exoplanets, with radial-velocity follow-up, appeared in Astronomy and Astrophysics
in May 2008 (Barge 2008, Alonso 2008 and Bouchy 2008
In May 2008, findings of two new exoplanets, as well as an unknown celestial object COROT-Exo-3b were announced by ESA. COROT-Exo-3b appears to be "something between a brown dwarf and a planet." In addition COROT has detected a faint signal, which could be another exoplanet with a radius as small as 1.7 Earth's radius. The existence of this object, which could be a rocky exoplanet, has not been confirmed yet.
Overviews in the popular press
Peer-reviewed manuscripts: COROT discoveries