Report - School of Physics

∼ 5 × 10 5 m, or 1.5 × 10 −4 R ⊙ . This is still significantly above the photometric stability
limits of 10 −7 −10 −8 AU, or 10 3 −10 4 m, derived by Svensson & Ludwig (2005)
for stars with log g = 4.4. Note, however, that this only concerns thermally-driven
granulation, thus determining only the lowest possible level of stellar astrometric
stability.
Understanding the Planetary Population of our Galaxy (Piotto): the proposal
underlines the importance of the field to ESA and to Europe. It argues that
most disciplines start with the discovery and study of individual objects, before
moving on to the more mature stage in which large, unbiased samples of objects
are studied. In the decade 2015–25, an open issue will be the discovery and characterisation
of large unbiased samples of planets down to habitable systems. This
should provide information necessary to understand how the environment and nature
of the parent star affects the resulting planetary population; how stellar metallicity,
multiplicity, crowding, and population influence the nature, habitability and
survival of planetary systems. The proposal suggests a transit-type follow-up to
Kepler/Eddington, using a significantly larger aperture and improved detector technologies
to obtain much improved samples/statistics; combined with the availability
of large (> 25 m) ground-based telescopes for follow-up spectroscopic observations.
Exo-planet Detection and Characterisation (Surdej): the proposal underlines
the general importance of the field to ESA and to Europe, and proposes to
intensify efforts towards a Darwin-like mission, including further emphasis on coronography,
perhaps as an ESA instrument on TPF-C. The proposal also underlines
the importance to astrobiology of sample-return missions in the Solar System, for
example to Mars, Europa, and Titan. Otherwise, no specific instrument approach
or design is considered.
Evolution of Atmospheres and Ionospheres of Planets and Exo-Planets
(André): the proposal considers a combination of in situ observations of Solar System
planets and remote sensing of exo-planets in order to advance understanding
of the long-term evolution of the atmospheres and ionospheres of planets (and large
moons), and to identify the important sources and sinks of atmospheres and ionospheres
of planets during different parts of their evolution. No specific instrument
approach or design is considered.
Planetary Habitability in the Solar System and Beyond (Bertaux): the
proposal underlines the general importance of the field to ESA and to Europe. It includes
suggestions for intensifying the search for (past) life on Mars through robotic
exploration in order to refine probability estimates of life beyond the Solar System.
It also notes the potential problem that ESA’s Darwin mission is presently designed
as its own candidate surveyor, and argues that a preliminary programme, possibly
ground-based, should undertake the advanced search so that Darwin can focus
its observing time on spectral acquisition of Earth-mass planets. The suggestion
is to conduct this survey, under ESA responsibility, using Doppler measurements,
reaching the required accuracies of 0.1–0.8 m s −1 through the accumulation of large
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