Horizon goes behind the scenes at NASA as they countdown to the landing of a 2.5 billion-dollar rover on the surface of Mars. In six days time, the nuclear-powered vehicle - the size of a car - will be winched down onto the surface of the Red Planet from a rocket-powered crane. That's if things go according to plan: Mars has become known as the Bermuda Triangle of space because..我们一路奋战,不是为了能改变世界,而是为了不让世界改变我们。