Liquid Water Found on Mars

There's a lake on Mars, it's been revealed today. It's not very big, but it is described as a proper body of liquid water probably around 22 metres wide and at least a metre deep. Scientists from the National Institute for Astrophysics say it's the first conclusive proof that H2O exists there currently, even though there's evidence of it having been there in the past. Water, of course, is a prerequisite for life as we know it.. Ed Howker has the details, and we talk to astrobiologist Manish Patel and Tom Kerss, an astronomer based at the Royal Observatory Greenwich.