It's an old question, but despite many estimates - based on Frank Drake's famous equation - that our own Milky Way galaxy could contain up to a million alien civilisations, the search for extra-terrestrial intelligence begun in 1961 has so far failed. Funding for SETI - as it's known - has also been a problem, although private money has partly filled the gap. But SETI scientists are now hopeful that, after a 25-year pause, the US Congress will mandate NASA to spend ten million dollars a year, for the next two years, renewing the search.

And it's not all about intelligence, as everyone agrees the discovery of life of any kind on another planet would be astounding - with some of the most exciting developments in this field much closer to home.

This week on The Real Story we ask a panel of space scientists: are we any closer to finding extra-terrestrial life? What new approaches are showing promise? How will we know if we've found it? And what might that life be like?

(Photo: VLA Radio Telescope, New Mexico. Credit: Education Images/UIG/Getty Images)