A presentation about the Darwin proposal will be made at the UK's National Astronomy Meeting at the University of Southampton on Friday 11th April by Dr Alan Penny of the Rutherford Appleton Laboratory.
Darwin will make a unique contribution to this search since it will be able not only to look for planets as small as the Earth but also to study their atmospheres. The search would concentrate on 300 Sun-like stars, many of them visible with the naked eye, which lie within 50 light-years of Earth -- next door in astronomical terms.
One exciting possibility would be the detection of large amounts of water in the atmosphere of an Earth-like planet, as this would indicate that the planet has oceans like the Earth. An even more exciting prospect would be the detection of considerable amounts of ozone. Such ozone could only be produced from plentiful oxygen, which in turn could only be generated by life. The detection of both water and ozone would mean that there was a significant amount of life presently alive on the planet. This life would be carbon-based oxygen-producing life, like the algae in the Earth's oceans or the vegetation on the Earth's continents.
Darwin's six telescopes would either be joined together by long arms in a rigid structure, or would each be mounted on individual spacecraft. In the former case, the rigid structure would rotate to build up the image. In the latter case, the individual spacecraft would have their own rocket motors, and dance around each other to build up the image. It is only recently that space technology has progressed to the stage where such a large telescope is feasible.
Another unique aspect of the Darwin Project is that it has to be sent deep into the solar system, somewhere between Mars and Jupiter, where it would be four times further away from the Sun than the Earth. This is to avoid the dust floating around in the inner Solar System. Known as 'zodiacal dust', this debris can actually be seen with the naked eye in rural areas at sunset and sunrise. Seen in the infrared, the zodiacal light is bright enough to drown out the faint light from planets. However, the dust does not extend beyond Mars, so it is possible to escape from it by locating the telescope further from the Sun.
The idea of using such a telescope deep in the solar system to avoid the zodiacal dust is the brainchild of Dr Alain Leger of the Institut d'Astrophysique Spatiale in Paris. Dr Leger is the Principal Investigator of the Darwin Project team.
Darwin is one of two alternative projects competing for selection as a future ESA 'Cornerstone' mission. Scientists and engineers will examine the technological and scientific aspects of both competitors before coming to a decision. If Darwin is selected, it would be launched around the year 2015. The winning project will not be chosen for several years.
The following illustrations are available via the WWW at the following location:
Further information on the mission is available at the Darwin WWW page.