In the first of two programmes, the BBC's science reporter Jason Palmer, meets the researchers behind Seti, the Search for Extra-Terrestrial Intelligence and looks at the prospects for success in the face of funding issues and the sheer size of the task.
He talks to Seti's co-founder Frank Drake as well as its current active researchers, including Seth Shostak, Jill Tartar and Doug Vakoch.
(Image: Computer artwork of our solar system. Credit: Science Photo Library)