Cosmic Vision: the CoRoT scientific community proposes 4 mission concepts
As CoRoT is collecting its first light curves, the scientific community prepares the next generation of planet-hunters and, on June 29th, submitted to ESA four mission concepts in the framework of the call for proposals of the European Cosmic Vision 2015-2025 scientific space programme. The goals, the technologies and the mission profiles of these satellites are of different kinds, but all aim at advancing our knowledge of exoplanetary systems 10 years after CoRoT and Kepler (launch expected in 2009).
The missions proposed are the following:
|PLATO, a very wide field photometric telescope working around the SEL-2 point and able, for at least 4 years, to observe a large sample of stars. PLATO has for objective to simultaneously study these stars and their planets, in order to better understand the formation and the evolution of the extrasolar systems. By observing many bright and nearby objects (100 000 stars, mv = 11-12), PLATO will open a new way by making possible to perform combined astronomical surveys from space and Earth (e.g. visible and UV spectroscopy, radial velocities) and thus significantly improving the scientific added value of these observations. PLATO may be seen as a super-CoRoT, gathering a large scientific community in Europe and beyond (USA, India), continuing the effort undertaken in the fields of stellar seismology and search for rocky planets by the transit method. Depending on the design chosen, PLATO will be able to explore all or part of the celestial vault. The PLATO proposal leader is Claude Catala, LESIA (Paris Observatory).|
SEE-COAST, a coronographic telescope around the SEL-2 point, equipped with a spectro-polarimeter working in the visible and near-IR. The main goal of SEE-COAST is to precisely characterize the light reflected by the exoplanets orbiting at more than 1 astronomical unit from their parent star (super-Earths or Jupiter-like giants), enabling to unveil if these planets host an atmosphere and what their main chemical elements and physical parameters are (albedo, temperature, pressure, rotation period, seasons…) Rings or planetary companions (moons) could also be detected. With a 1.8-m diameter mirror, the SEE-COAST telescope demands razor-sharp optics to reach the requested level of image quality performances. Several concepts of coronographic patterns are under study and trade-off. The SEE-COAST proposal leader is Jean Schneider, LUTH (Paris Observatory).
|PEGASE, a 3-spacecraft formation flying interferometry mission aiming at preparing DARWIN and proving the concept in orbit. It is a Bracewell interferometer (nulling interferometry, cancelling out the signal of the object on-axis), enabling spectroscopic measurements in near-IR of the hot Jupiters (also called Pegasids) and the exozodiacal light coming from the dust disks. The PEGASE flotilla could be injected into an Earth high elliptic orbit or around the SEL-2 point. It is based upon the R&D studies led at the moment in the field of nulling interferometry (Persee test bench) and CNES feasibility studies on formation flying. Beyond the technology demonstration goals, PEGASE could scientifically prepare the DARWIN mission, bringing an improved knowledge of the stellar environments and performing a first physical and chemical characterization of potential individual planetary targets and of their atmosphere. The PEGASE proposal leader is Marc Ollivier, IAS (Orsay).|
DARWIN, lastly, a flagship space interferometry mission appearing for several years among the future programmes of ESA in the field of the search for habitable planets. DARWIN is made up of 5 spacecraft flying together, with 4 collector satellites (mirror diameter between 1 and 2 m) and one beam-combiner satellite. It can be seen as a double Bracewell interferometer (which cancels out not only the star light, but also the exozodiacal light), working in near and mid-IR and able to detect the combined occurrence of absorption bands of three molecules considered up to now as the best signature of biological activity : water, ozone and carbon dioxyde. Beyond this exhilarating goal, the DARWIN instrument, with its interferometric baseline of 500 m in the image mode and angular resolution performances comparable with those of VLTI, is also designed to be used as a powerful tool for a number of disciplines in astrophysics (e.g. study of our Galactic centre, star formation, growth of black holes, matter in supernova ejecta). DARWIN, as all the great-size space telescopes, will be flying around the SEL-2 point and will most likely be implemented in a large international cooperation. The DARWIN proposal leader is Alain Leger, IAS (Orsay).
To be exhaustive, to these four proposals coming from the CoRoT community may be added two other multi-purpose instrument concepts, Luciola and Fresnel, likely to bring contributions to exoplanetary science.
The missions short-listed by ESA will be known in October 2007, after a selection process lasting all this summer. Then will start a technical and finantial assessment phase, leading to decide to build one class-M mission and one class-L mission, between 2015 and 2020.
For further information on the Cosmic Vision programme.