Thanks to Centauri Dreams for the pointer to the ESA DARWIN proposal now here (high-resolution version also here). DARWIN is a space mission to detect the presence of life on other planets by spectroscopy: looking for biomarkers such as the presence of Ozone, water and methane together on terrestrial-sized planets. These are groups of gases that collectively would imply the presence of life.

Unfortunately it appears that DARWIN is slipping: its not currently hardware-funded, and has a planned launch-date of 2020, having slipped from 2012. This is when NASAs alternative Terrestrial Planet Finder and Space Interferometry Mission have been defunded indefinitely.

At the same time, the French COROT mission has just announced its first month-long series light-curves. COROT hunts for Earth-sized planets: it's a small space telescope that stares at the same patch of sky for long periods, looking for changes in the amount of light from stars that indicate a planet passing in front of a star. It has been much more successful than expected, having already announced its first exoplanet detection in April. NASA is also launching a similar mission, Kepler, in 2008.

So we face the prospect that any day now we may know of Earth-sized planets in a Habitable zone, and yet be over a decade from determining if they could contain life.

So do we have any other tricks up our sleeves? Other possibilities include the James Webb Space Telescope, the successor to the Hubble. With a launch planned in 2013, it would be able to determine some atmospheric features found in COROT detections, but would be too expensive to do the planet-hunting Darwin could do. Perhaps this could be imroved with occulters such as UMBRAS (thanks to enzo). Other novel detection missions include the Voyager Interstellar Mission (via), reusing exisiting 'end-of-life' spacecraft as telescopes.

And finally, could ground-based telescopes do it? tests have just started on a new 10M telescope in the Canaries that could help; in terms of larger scopes, colleagues of mine in NUI Galway have been collaborating on the design of Euro50, a proposed 50M telescope. Together with new techniques such as spectral deconvolution (via) may help.