The Mars rover Curiosity, now just days from landing on the Martian surface, is something of a technological marvel, unlike anything that has come before it. It packs some of the most high-tech scientific hardware ever sent into space aboard a robotic spacecraft, delicate tools and complex systems that will allow it to conduct the most sophisticated science ever performed on the surface of Mars.
But first NASA engineers have to slow it from 13,000 miles per hour to zero in just seven minutes and place carefully into an extremely hostile environment. It's a delicate act, an art form really, but it's been done before. Curiosity doesn't stand alone, but on the shoulders of giants.
Curiosity's landing will be the most technologically dazzling landing on another planet ever conceived by human spaceflight engineers, but it isn't happening without the benefit of experience. Since the 1960s, the United States and Russia (then the Soviet Union) have been building expensive, sophisticated machines and slamming them into other planetary bodies. Some missed their targets completely, some were crushed like soda cans, some were bashed to pieces, and some lucky few made it long enough to beam a signal back home.