COROT stands for Convection Rotation and planetary Transits and is a big step forward for the ESA for the search after extrasolar planets. It is the first mission for the search after rocky planets around nearby stars. Furthermore it is the first European Mission for asteroseismology at other stars.
The telescope launched in December 2006 with a Soyuz-Fregat launcher at Baikonur, Kazakhstan, because this was less expansive than a launch by an Ariane rocket. COROT is a mission led by the French National Space Agency, CNES and was first proposed in December 1996. COROT was placed on a circular polar orbit with an altitude of 827 km. The durability is planned for 2,5 years.
COROT's main tasks are:
to detect planets in other stellar systems as they pass in front of their parent stars, blocking some of the light.
to study stellar interiors by detecting the ripples spreading across a star's surface, altering its brightness. The exact nature of the ripples allows astronomers to calculate the star's precise mass, age, and chemical composition.
It consists of a 30-centimetre space telescope and uses the telescope to monitor closely the changes in a star's brightness that comes from a planet crossing in front of it. The telescope is made of two mirrors which are an afocal system (reducing the size of the light beam). The mirrors are made of zerodur and the bar linking is made of composite material with a very low thermal coefficient. In addition COROT use two cameras - one for each of the two mission objectives (exoplanet search and asteroseismology), and the on-board computer processors.
While it is looking at a star, COROT is also able to detect ‘starquakes’, acoustical waves generated deep inside a star that send ripples across a star's surface, altering its brightness.
This technique is known as asteroseismology and ESA's Solar and Heliospheric Observatory (SOHO) has been taking similar observations of the Sun for years.
From the ground, the only planets detected around other stars have been giant gaseous worlds (Jupiter-like planets), over 10 times the diameter of the Earth. Most of the planets COROT will detect are expected to be 'hot-Jupiters' those with orbits of 50 days or less (closer to their parent star than Mercury is to the Sun). Each hot Jupiter is a large gas giant planet in close orbit around its central star. An unknown percentage of the planets detected by COROT are expected to be rocky worlds, maybe just a few times larger than the Earth.
In most cases, such proximity to a star would scorch them beyond habitability. However, if such a world were discovered around a red dwarf star, it could be placed at exactly the right distance for liquid water to exist on its surface.
The COROT telescope was build by Thales-Alenia-Space in France and over 100 engineers and over 80 scientists are involved in this mission. CNES and the CNRS are responsible for 70% of the costs of this program, the rest comes from several other European countries plus Brazil.
ESA then plans to continue its search for Earth-like worlds into the second decade of the century with the launch of the Darwin mission. This flotilla of 4 or 5 spacecraft will take pictures of Earth-like worlds, allowing scientists to search for signs of life.