Cosmic Vision 2015-2025: Planets and Life
20 January 2006
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.
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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. |
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| 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. |
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| 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. |
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Goal Concepts
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