Earths on the horizon

This satellite is the first which is sufficiently sensitive to unmask small planets capable of sheltering life elsewhere in the Universe. In ten years or so astronomers have already discovered around 200 exoplanets around other suns but they have not yet fished out from their nets anything that resembles our good old Earth, or even anything comparable to the other planets of the Solar System: the majority of them are hot Jupiters, in other words large gaseous planets gravitating in very close proximity to their star.

It should not however be concluded from this that our Solar System is unique: the technologies used up until now only enabled the detection of exoplanets which cause relatively large scale observable effects, such as hot Jupiters. To have any hope of locating exoEarths, more powerful space based instruments were necessary. In brief, CoRoT was needed.

Observations concerning the first exoplanet, detected during CoRoT’s first exploratory phase, were made public in the month of May. But we were out of luck: it’s not an Earth. It is a Jupiter type giant, with a mass equivalent to 1.3 times that of Jupiter and whose rays are 1.78 greater than that of Jupiter. The host star is a Sun type star. In brief, in the field of astrophysics nothing earth shattering was revealed. But, once again, the precision with which the transit of this exoplanet was observed was already greater than that anticipated in the satellite's technical specifications, even though the analysis of the data has not yet been completed. For this ‘exoplanet' aspect of the mission the future is also very promising, and Liège researchers may soon find themselves amongst the discoverers.

In total, CoRoT should discover hundreds, and probably thousands, of exoplanets. This considerable growth in the samples of exoplanets will provide vital statistics concerning the formation of planetary systems: what proportion of stars is encircled by a planetary system? Is there a correlation between the type of star and the type of planet gravitating around it? Etc.

In the aftermath of CoRoT

Amongst all these exoplanets, astronomers hope to find several dozen which are ‘habitable’, that is to say rocky planets located at a distance from their star at which the development of life is possible. Certainly, 'habitable' does not mean 'inhabited'. To overcome this last step in the search for extraterrestrial life we will need to wait for successor missions, such as Kepler or Darwin, which will supply spectroscopic images of exoplanetary atmospheres in order to detect within them the traces of CO₂, water and ozone. These missions could take off within a year or two in the case of the Kepler mission, and within a good ten years in the case of the Darwin mission. Whilst we wait, all eyes are turned to CoRoT.