Undated-AP -- The shuttle is no more than a heavy glider as it returns to Earth.
Roger Launius (LAW'-nee-uhs), a spaceflight historian at the National Air and Space Museum, says "it has all the aerodynamic capability of a brick."
He says the landing process begins half a world away from the runway as the shuttle turns around and fires rockets to slow down. That brings its orbit closer to Earth.
The spacecraft then turns around to fly forward -- without rocket power -- at a precisely controlled angle. Most of the flying is controlled by computer.
Launius says at about 400-thousand feet, while flying at more than 16-thousand miles-an-hour, the shuttle begins a series of swooping banks to slow further. It usually makes one last wide turn to approach the runway. And there's no second chance.
He says, "It comes down real fast and real hard."