Video Transcript: Curiosity Rover's Risky Mars Landing

Entry descent and landing, also known as EDL, is referred to as a seven minutes of Terror because we've got literally seven minutes to get from the top of the atmosphere to the surface of Mars, going from 13,000 miles an hour to zero, in perfect sequence, perfect choreography, perfect timing, and the computer has to do it all by itself with no help from ground.  If any one thing doesn't work just right, it's game over.  

We slam into the atmosphere and develop so much aerodynamic drag our heat shield it heats up and it glows like the surface of the Sun, 1,600 degrees.  During entry the vehicles not only slowing down violently through the atmosphere but also we are guiding it like an airplane to be able to land in a very narrow constrained space.  This is one of the biggest challenges that we're facing and one that we have never attempted on Mars.  

Mars is actually really hard to slow down because it has just enough atmosphere that you have to deal with it otherwise it will destroy your spacecraft.  On the other hand, it doesn't have enough atmosphere to finish the job.  We're still going about a thousand miles an hour so that point we use a parachute.  

The parachute is the largest and strongest supersonic parachute that we've ever built to date.  It has to be able to withstand 65,000 pounds of force even though the parachute itself only weighs about 100 pounds.  When it opens up that fast it's a neck snapping nine G’s. 

At that point we have to get that heat shield off.  It's like a big lens cap blocking our view of the ground to the radar.  The radar has to take just the right altitude and velocity measurements at just the right time or the rest of the landing sequence won't work.  

This big huge parachute that we've got it'll only slow us down to about 200 miles an hour and that's not slow enough to land, so we have no choice but we've got to cut it off, and come down in rockets.  Once we turn those rocket motors on, if we don't do something, we’re going to smack right back into the parachute.  So the first thing we do is make this really radical divert movement.  We fly off to the side, diverting away from the parachute, killing our horizontal velocity and our vertical velocity, getting the rover moving straight up and down so it can look at the surface with its radar and see where we're going to land and we head straight down to the bottom of a crater, right beside a six-kilometer-high mountain.  

We can't get those rocket engines to close to the ground, because if we were to descend propulsively, with our engines all the way to the ground, we would essentially create this massive dust cloud.  That dust cloud could then go and land on the rover.  It could damage mechanisms and it could damage instruments.  So the way we solve that problem is by using the sky crane maneuver.

Twenty meters above the surface, we have to lower the rover below us on a tether that's 21 feet long and then gently deposit it, on its wheels, on the surface.  

As the rover touches down and is now on the ground, the descent stage it's in a collision course with the rover.  We must cut the bridle immediately and fly the descent stage to a safe distance from the rover.

Curiosity Touchdown, 10:31 p.m. PDT.  August 5, 22012