What Kinds of Life Forms Could Actually Live on Mars?

Yesterday, NASA reignited our hopes of finding alien life when it announced the first direct evidence of liquid water on Mars. But before we start indulging in fantasies of space crabs and reptilian beings, we ought to remember that Mars is a frigid world with a thin atmosphere. And that raises an obvious question:… »9/29/15 3:03pm9/29/15 3:03pm