MarsNews.com

Twin Mars rovers proving well worth the expense Houston Chronicle

Water can exist without life, but life requires water. The Mars rover Opportunity has found evidence that water once flowed on Mars, and that justifies more missions to search for signs of life.
Pictures taken by the NASA rover of sedimentary rocks suggest that salt water once pooled and sometimes flowed on Mars. If true, Mars once had a warmer climate more conducive to life, perhaps only microscopic forms.