Down That Long Dusty Trail USC

While Mars can claim some unique features – the largest volcano and the deepest canyon in the solar system – its rocky, dusty, cold landscape has yet to yield signs of the ultimate prize: life. Three simple words – follow the water – have become the mantra of astrobiologists studying the Red Planet because the presence of water is believed to be a prerequisite for life, either past or present. But as scientists look for evidence of water on Mars, they are faced with an underlying dilemma: Will they know life when they see it?