InSight Landing on Mars
Rob Manning: Although we've done it before, landing on Mars is hard. And this mission is no different. The process to get from the top of the atmosphere of Mars to the surface we call "entry, descent, and landing" or EDL.
It takes thousands of steps to go from the top of the atmosphere to the surface. And each one of them has to work perfectly to be a successful mission.
The process starts well above the atmosphere of Mars. The cruise stage faces the Sun. It also has its radio antenna which faces Earth. But now we don't need the cruise stage. Its job is done. The next step, just 7 minutes before arriving to the top of the Mars atmosphere, is to separate the cruise stage.
Before you hit the top of the atmosphere though, the space capsule has to orient itself so that the heat shield is precisely facing the atmosphere.
Now the fun begins. The vehicle is moving at nearly 13,000 miles an hour. But it's hitting the top of the atmosphere at a very shallow angle. 12 degrees. Any steeper, the vehicle will hit the thicker part of the atmosphere and will melt and burn up. Any shallower, the vehicle will bounce off the atmosphere of Mars.
At the very top of the atmosphere it's about 70 miles above the surface of Mars. And the air is starting to get thicker and thicker and thicker. As it does that, the temperature in the heat shield gets well over a thousand degrees centigrade--enough to melt steel.
Over the next 2 minutes, the vehicle decelerates at a back-breaking 12 Earth G's. From 13,000 miles an hour to about 1,000 miles an hour.
At about 10 miles above the surface of Mars a supersonic parachute is launched out of the back of the vehicle. Fifteen seconds after the parachute inflates it's time to get rid of the heat shield. Six pyrotechnic devices fire simultaneously, allowing the heat shield to fall and tumble away from the vehicle, exposing the lander to the surface of Mars.
Ten seconds after the heat shield is dropped, three pyrotechnically deployed legs are released and locked for landing.
About a minute later the landing radar is turned on, sending pulses toward the surface of Mars as the vehicle starts to try to measure how high it is above the surface and how fast it's going.
At about a mile above the surface of Mars the lander falls away from the backshell and lights its engines. And very quickly the vehicle must rotate out of the way so that the parachute and the backshell doesn't come down to hit it.
The last thing that has to happen is that on the moment of contact the engines have to shut down immediately. If they don't, the vehicle will tip over.
So if all the steps of entry, descent, and landing happen perfectly and we are safely on the surface of Mars, we'll be ready to do some exciting new science.