The Mars explorer named Curiosity was launched successfully on Saturday and is expected to land on the planet on August 6, 2012. Because Curiosity is a much larger object than previous explorers, engineers needed to develop a new way of giving it a soft landing and this new technique is causing some anxiety to mission scientists about whether the rover can survive the landing. Some of them refer to the final stages of the landing as ‘six minutes of terror’.
You can see an animation (made back in 2005) of what the landing should look like.
Here is a test run of the final stage done in the laboratory.