Life has not yet been found on Mars, and no one is sure whether it will be. But some researchers say it is not too early to consider the possibility that humans could do irreversible damage to indigenous Martian life. — Should Mars be treated like a wildlife preserve? – space – 05 February 2009 – New Scientist
My opinion? hell yes. we need to be careful that we don’t contaminate the entire planet with our own filth, if only to find out of Mars has any life of it’s own, even if it’s in microbe form.