Sky Crane 
The plan for landing the Curiosity rover on Mars sounds like something created by the “Mythbusters”: Use a heat shield, a parachute, retrorockets, and a “sky crane” — a hovering platform that’ll winch the rover the final few feet to the surface. Oh, and you’ve got just seven minutes for the entire sequence — and unlike one of the Mythbusters’ favorite sayings, failure is not an option.
Curiosity is scheduled to land tonight in Gale Crater, a wide basin with a tall mountain at its center.
The crater may once have been filled with water. During its two-year main mission, the nuclear-powered rover will look for evidence of that ancient water in layers of rock at the base of the mountain, plus the rocks and dirt around the mountain. Its measurements will help scientists determine whether the region was habitable in the distant past.
That mission depends on a successful landing, which is the most complicated yet attempted.
A precisely controlled entry into the Martian atmosphere should place Curiosity inside a target landing zone that’s just 12 miles long.
Earlier rovers used airbags to cushion their final drop. But Curiosity is too big for that — it weighs a ton, and it’s the size of a minivan. Instead, a rocket-powered descent stage will hover just 65 feet above the surface and use the sky crane to winch the rover to a gentle landing — and the start of the most extensive exploration of the Martian surface to date.
Script by Damond Benningfield, Copyright 2012