NASA’s Curiosity Rover is set to touch down on Mars on August 5 at exactly 10:31pm PDT. Curiosity, or the Mars Science Laboratory (MSL), is on a mission to study the climate, geology, and potential for past or present life on the red planet. But did you know there is something more… ominous afoot? In this video, set to appropriately terrifying music, mission engineers explain what “7 minutes of terror” means for them.
When the probe reaches Mars, it has to descend through the atmosphere. That journey takes 7 minutes. But when Curiosity is dropping to the land below, it will take 14 minutes for its signal to reach Earth millions of miles away. By the time NASA knows whether or not the plucky little rover has survived, it will have been either safely on Mars, or smashed into a thousand pieces for 7 minutes.
This is an incredibly complicated landing procedure with absolutely no margin for error. The atmosphere is actually just the wrong density for landings. We’re told, over sufficiently scary music, that the air on Mars is just thick enough that heat shielding is needed for decent, but still too thin to decelerate the craft very much. The Martian atmosphere is about 1% as dense as Earth’s.
To further slow the vehicle, a supersonic parachute will be deployed and the heat shield jettisoned, having served its purpose. At this point, the rover will still be plummeting toward the ruddy surface of Mars at over 200mph. The answer to this, like so many of life’s problems, is more rockets.
The rover drops off the bottom of the capsule, and uses a rocket assembly to get out of the way of the parachute and slow itself down. Slowly, the rover will head to the surface, all the time probing with its radar. To prevent dust from being kicked up and damaging the rover, the rocket assembly will be used to hover 20 meters above the ground while just the vehicle is lowered on a tether.
The last hurdle to be overcome is disposing of the landing rockets. The rocket stage will be shot off in the distance, leaving Curiosity on its own on a whole new world. Truly, this is a terrifying 7 minutes for the folks that spent years planning and developing this mission.