Nasa scientists may still be celebrating their discovery of liquid water on Mars, but they now face some serious questions about how they can investigate further and look for signs of life on the red planet. The problem is how to find life without contaminating the planet with bugs from Earth. The Guardian view on the discovery of liquid water on Mars: cause for great celebration
Editorial: Now the search is on to find living organisms on the red planet. Even traces of primitive microbes would rank among the most important discoveries in history
