Humans are poised to try to colonise Mars some time in the next few decades - and if there IS life on Mars, we'll have to be careful not to jeopardise it.
David Weintraub is a physicist and astronomer who lectures at Vanderbilt University in Tennessee, and joins us to mull over the ethical dilemmas that inter-planetary colonisations throw up.
Photo: By NASA/JPL-Caltech [Public domain], via Wikimedia Commons
