New roadmap to guide ESA in search for exoplanets
28 Oct 2010The idea of other planets hidden in the vastness of space has long captured human imagination and there has been a recent explosion in the number of exoplanets discovered, with the total fast approaching 500. As the research community heads towards this milestone, ESA called on them for recommendations on how the Agency could build upon this success. The result is a recently published roadmap from the Exoplanet Roadmap Advisory Team (EPR-AT), which looks at the future of the field and how to reach their ultimate, long-term goal: finding an Earth-like planet with possible signatures of life.
Finding a twin of our own planet has long been the holy grail of exoplanet research. But whilst it represents the end destination for the new roadmap, the journey is equally important as it allows a better understanding of exoplanets and exoplanetary systems themselves. The authors of this roadmap, who come from research institutions across Europe, focus on three key areas: the continued detection of ever smaller exoplanets, the characterisation of their internal structure, and analysing the composition of their atmospheres, including the search for biosignatures.
Biosignatures would provide the best indication yet of life on other worlds but are likely outside of the realm of present-day facilities. Broadband photometry or low resolution spectroscopy from ground-based telescopes can already reveal some molecular species in exoplanetary atmospheres, but detection of actual biosignatures on small, Earth-like planets will likely require future, dedicated facilities, on ground and in space.
"Space telescopes aren't just important because they can find smaller planets," notes Malcolm Fridlund, Secretary for EPR-AT. "They also provide more detail than can be achieved from the ground, such as spectroscopic information about terrestrial atmospheres."
Such research illustrates a shift in emphasis; as space missions like Kepler and COROT detect more and more planets it is no longer satisfactory just to find them, researchers want to characterise them too in order to conduct detailed comparative planetology. Ground-based telescopes, equipped with highly sensitive spectrometers, are also crucial in both following up the initial space-based detection and analysing the planet's characteristics. With this synergy in mind the authors of the report make recommendations across three broad categories: ground, space and technology.
There may, however, be a catch in one hypothesis underpinning the search for a 'second Earth'; having a terrestrial mass might not necessarily make it an analogue of the Earth. "We cannot make an effective search for terrestrial planets until we properly understand what that term means. Recently two small bodies with approximately the same mass and not too different diameter have been found. One of them has characteristics compatible with its being made of iron and rock, the other of ice and rock: are both terrestrial?" asks Fridlund. By travelling down the route outlined by EPR-AT the community will be able to better define what they are looking for. "Answering this question will help lead us to the ultimate goal of finding out if there is life elsewhere in the Universe," Fridlund adds.
For further information please contact:
Malcolm Fridlund, Secretary, Exoplanet Roadmap Advisory Team
Notes for Editors:
The Exoplanet Roadmap Advisory Team (EPR-AT) was appointed by ESA with the purpose of advising the Agency on a scientific and technological roadmap to pursue in order to address one of the most exciting goals in modern astrophysics: the discovery and characterization of exoplanetary systems, with the ultimate, long-term goal of detecting biomarkers on habitable planets.
The EPR-AT was led by Artie Hatzes, Thuringer Landessternwarte, Germany, and included Anthony Boccaletti, Observatoire de Meudon, France; Rudolf Dvorak, Institute for Astronomy, University of Vienna, Austria; Giusi Micela, INAF - Osservatorio Astronomico di Palermo, Italy; Alessandro Morbidelli, Observatoire de la Cote d'Azur, France; Andreas Quirrenbach, Landessternwarte, Heidelberg, Germany; Heike Rauer, German Aerospace Center (DLR), Germany; Franck Selsis, Laboratoire d'Astrophysique de Bordeaux (LAB), France; Giovanna Tinetti, University College London, United Kingdom; Stephane Udry, Université de Genève, Switzerland; with Anja C. Andersen, Dark-Cosmology Center, Copenhagen, Denmark as external expert, and Malcolm Fridlund, ESA, as secretary.
The roadmap was prepared by the EPR-AT following a consultation process with the scientific community, which included a Call for White Papers, presentations at several international conferences and a dedicated, open workshop at which the draft roadmap was discussed.