It is a view that astronomers would die for: a shimmering, blue, alien world with oceans and continents and vegetation changing colour with seasons. A vision like this, across the galactic void, would be unambiguous proof of the existence of extraterrestrial life. Planets outside our solar system are many hundred thousand billion miles distant, however, and the prospect of observing them has been considered utterly remote by most scientists. But European researchers have now begun work on a research programme that could culminate in such an instrument, a flotilla of orbiting mirrors that could return clear pictures of exo-planets, worlds that circle other stars. 'It is the one irrefutable way of deciding if another world has life on it,' said Professor Antoine Labeyrie, of the Observatoire de Haute Provence, in France. 'If you can see there is chlorophyll and vegetation that changes colour as plants die or flourish as the planet swings round its sun, then you have found a world with life on it.

Whether this has evolved to a complex level is a different matter.' Labeyrie's space telescope is unlikely to be built for decades, although preliminary optical tests have already begun. In the meantime, the European Space Agency (Esa) is preparing to launch a programme aimed at developing less complex missions for pinpointing stars with life-bearing planets. If these succeed, the Exo-Earth Imager could follow them.

View: Full Article | Source: The Guardian