Nearly seven months after landing, NASA’s last vehicle, the Perseverance, will still survive the “seven minutes of terror” as its landing on Mars is dubbed before the ultra-dangerous maneuver.
The chosen location, the Jagero Crater, is the most dangerous landing site ever built. In seven minutes, the rover must go to zero at a speed of 20,000 km / h.
The landing will take place on Thursday at 8:55 pm GMT (3:55 pm in Washington, 9:55 pm in France).
-130 km: entering the atmosphere-
Ten minutes before Mars entered the atmosphere, the ship was separated from the cruise phase which supplied it with fuel during the voyage.
It is composed only of a rear shield, a heat shield in front, and, caught between the two, the descent stage, which is connected to the rover.
At an altitude of about 130 km, it enters the atmosphere at a speed of 20,000 km / h, causing friction to reach temperatures of 1,300 ° C. The heat shield protects the rover from this scorching heat.
-11 km: Inauguration of Parachute-
But the atmosphere is not enough to slow the ship, which is still moving at 1,500 km / h.
At a height of about 11 km, a huge supersonic parachute of 21 m diameter is positioned in the rear shield, at a suitable time according to the remaining distance for the landing location.
This slows the ship down to about 300 km / h.
-9 km: heat shield released-
20 seconds after opening the parachute, the heat shield is released: the rover it was guarding first encountered in a Martian environment.
A whole new technology, called “Terrain Relative Navigation” (TRN), comes into play: images recorded live by the ship’s cameras are compared to maps recorded in its system, where to avoid Dangerous zones are pre-defined. Keeping these figures in mind, the ship decides on the final landing location.
-2 km: Retro-propelled stage-
At an altitude of about 2 km, the rear shield – and its parachute – are dropped.
The rover is no longer associated with the landing position, which is equipped with eight motors at the bottom, which are lighter to slow it down. After maneuvers to get away from the parachute, the rover descends vertically, just above its landing site.
-20m: Separating the rover-
At about 20 meters above the ground, it reached a speed of 2.7 km / h, slower than the speed at which a man walks. The rover then descends with the cable for a system of pulse, during the last fifteen seconds (a phase called “skycrane”).
The vehicle deploys its wheels at this time. When the latter realizes the ground, the lines are cut and the descent stage makes one final push to crash as far as possible.
Due to the delay in transmission between Earth and Mars, when the landing would be confirmed by NASA, it would have actually occurred several minutes earlier.