NASA engineers referred to the most crucial moments in the Mars Curiosity mission last summer as the "seven minutes of terror." During that time, without the guidance or control of any humans back on earth, the rover had to enter the martian atmosphere, descend from an initial speed of 13,000 miles per hour, and land on target in one insanely expensive, intact piece.
"And the computer," as the engineer in this dramatic little NASA trailer explains, "has to do it all by itself":