Cosmic Vision 2015-2025: Planets and Life (Forwarded)

ESA News
http://www.esa.int

20 January 2006

Cosmic Vision 2015-2025: Planets and Life

We present the first in a series of four articles which look in detail at
the different concepts supporting the main themes of the Cosmic Vision --
Space Science for Europe 2015-2025.

Theme 1 -- What are the conditions for planet formation and the emergence
of life?

A question that fascinates mankind is what was the succession of events
after the Big Bang and the formation of stars and galaxies, and under
which conditions, that led to the origin of life on Earth? Equally
captivating is the question of whether life exists elsewhere in the
Universe and, if so, in what forms, on which kind of planets and linked to
which type of stars.

We are now at a unique moment in human history. For the first time, we are
able to build instruments that allow us to investigate directly how unique
the Earth is and whether or not we are alone in the Universe. Discovering
Earth's sisters and possibly life is the first step in the fundamental
quest of understanding what succession of events led to the emergence and
survival of life on Earth. For this, we need to know how, where and when
stars form from gas and dust and how, where and when planets emerge from
this process. This is certainly one of the most important scientific goals
that ESA and Europe could set themselves.

1.1 From gas and dust to stars and planets

While our understanding of stellar evolution is making giant leaps
forward, we still lack a comprehensive theory explaining why and how stars
form from interstellar matter and, apparently quite often, planetary
systems with them. The formation of planets has to be considered in the
wider context of star formation and circumstellar disc evolution.

Goal

Map the birth of stars and planets by peering into the highly obscured
cocoons where they form

Concepts

1. Investigate star-formation areas, proto-stars and proto-planetary discs
and find out what kinds of host stars, in which locations in the Galaxy,
are the most favourable to the formation of planets

2. Investigate the conditions for star formation and evolution

Mission Scenarios

1. Far-infrared observatory with high spatial and low to high spectral
resolution

1.2 From exo-pamets to biomarkers

To guide the theory of planet formation, a complete census of all the
planets from the largest to the smallest out to distances as large as
possible is required. This can be achieved by making use of a variety of
detection techniques, ranging from the high-precision measurement of
radial velocities, high-accuracy astrometry to detect the tiny reflex
motion of the star in the plane of the sky, and photometry to measure the
changes of brightness during a transit or during a gravitational lensing
event.

Goal

Search for planets around stars other than the Sun, looking for biomarkers
in their atmospheres, and image them

Concepts

1. Direct detection of Earth-like planets,with physical and chemical
characterisation of their atmospheres for the identification of unique
biomarkers

2. Systematic census of terrestrial planets

3. Ultimate goal: image terrestrial planets with a large optical
interferometer

Mission Scenarios

1. Near-infrared nulling interferometer with high spatial resolution and
low resolution spectroscopy

2. Terrestrial planet astrometric surveyor

1.3 Life and habitability in the Solar System

The quest for evidence of a second, independent genesis of life in the
Solar System must begin with an understanding of what makes a planet
habitable and how the habitable conditions change, either improving or
degrading with time. For instance, the environmental conditions on the
Earth today are not the same as when life first arose on this planet. The
early Earth, with its oxygen-free atmosphere, high ultraviolet radiation,
high temperatures and slightly acidic waters, could not support the highly
evolved life forms so familiar to us. However, life could not have arisen
on a planet with the environmental conditions that exist on Earth today.

Goal

Explore in situ the surface and subsurface of solid bodies in the Solar
System most likely to host -- or have hosted -- life

Concepts

1. Mars is ideally suited to address key scientific questions of
habitability. Europa is the other priority for studying internal
structure, composition of ocean and icy crust and radiation environment
around Jupiter

2. Environmental conditions for the appearance and evolution of life
include not only geological processes, the presence of water and
favourable climatic and atmospheric conditions, but also the magnetic and
radiation environment commanded by the Sun's magnetic field

Mission Scenarios

1. Mars exploration with landers and sample return

2. Europa orbiter and/or lander in Jupiter Exploration Programme (JEP)

3. Solar polar orbiter to chart the Sun's magnetic field in 3-D

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RELATED PUBLICATIONS

* ESA BR-247: Cosmic Vision -- Space Science for Europe 2015-2025
http://sci.esa.int/science-e/www/obj...objectid=38542