Of all the planets and moons in our solar system other than Earth, the one with the greatest possibility for the discovery of life is still Mars (Report, 17 February). In orbit around Mars are a number of probes, some of which have detected the presence of methane plumes from the Martian surface. Methane gas reacts quickly with its environment and disappears unless something continuously replenishes it. Living things are one source of methane on Earth. Thus far every lander sent to Mars has been decontaminated so that, should evidence of life be found, we can be assured that it is native to Mars and not an Earth invader. Landing an impossible-to-decontaminate human being on a world that could harbour an independent ecosystem which has followed a completely different evolutionary track from our own would be the height of irresponsibility scientifically and morally. It risks destroying one of the most fascinating and beneficial research opportunities ever open to mankind. And all for a reality TV show? Really?! Until we can determine through robotic missions whether or not Mars is a dead world, we must be responsible and keep human beings off the red planet.
Professor Todd Huffman
Particle physics, Oxford University
