Report - School of Physics
Report - School of Physics
Report - School of Physics
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Without any further mission dedicated to terrestrial planet searches, there will be no<br />
real understanding <strong>of</strong> the distribution <strong>of</strong> such planets in general (e.g., in other parts<br />
<strong>of</strong> the Galaxy or in clusters), and the number <strong>of</strong> targets discovered by Kepler may in<br />
any case be very small. Eddington would observe stars in a variety <strong>of</strong> environments,<br />
i.e., field stars and stars in open clusters, and will thus consolidate the search for<br />
planets across different stellar parameters (including metallicity, age, mass, binary<br />
status, density <strong>of</strong> surrounding stellar population, etc.).<br />
More generally, experiments need repeatability: single experiment results always<br />
provoke more questions, and if the results are controversial it is only reasonable that<br />
they are checked independently. Having just one mission aimed at the detection <strong>of</strong><br />
terrestrial planets appears risky and inadequate, in particular considering the effort<br />
being made for future missions that aim at studying these planets (Darwin/TPF).<br />
The present working group emphasises the value <strong>of</strong> aiming to launch such a mission<br />
at the earliest opportunity, preferably before 2010. Should it turn out that it is only<br />
possible to launch Eddington significantly later, ESA should consider a larger-scale<br />
post-Kepler mission on a longer time schedule.<br />
OWL and Kepler/Eddington<br />
The OWL science case is currently not so much based on finding Earth-like planets,<br />
but rather on imaging or spectroscopy <strong>of</strong> nearby candidates detected by other means.<br />
To this extent OWL’s primary science case is as a follow-up instrument. On the<br />
other hand there are no prospects other than Darwin/TPF for finding all nearby<br />
Earth-mass planets (transits can only discover a small fraction), so its use for Earthmass<br />
planet searches in a survey-type mode would be valuable, and should add to<br />
its contribution to the field. Such a survey might be undertaken during the mirrorfilling<br />
phase, although detailed feasibility studies <strong>of</strong> this approach have not yet been<br />
made.<br />
OWL/Dome C versus Darwin/TPF<br />
As summarised in Section 3.1.2 and Table 8, appropriate Antarctic observations<br />
could at least partially compete with some aspects <strong>of</strong> the Darwin/TPF missions.<br />
However, some key spectral regions are accessible only from space, e.g. O 3 at 9.6 µm<br />
and CO 2 at 15 µm. Trade-<strong>of</strong>fs would depend on the number <strong>of</strong> objects visible,<br />
the S/N ultimately attainable from Darwin, and the accessible spectral range and<br />
the resulting scientific information that can be inferred for exo-planetology and<br />
exobiology. Further investigations will be needed in order to understand whether<br />
such Antarctic-based observations could be considered as realistic in the medium<br />
term.<br />
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