NASA said: “To nail the timing of this critical event, Perseverance uses a new technology – Range Trigger – to calculate its distance to the landing target and open the parachute at the ideal time to hit the mark.”
The 70.5ft-wide parachute will open about 240 seconds into the flight at an altitude of about seven miles.
Then, just 20 seconds after deployment, Perseverance’s heat shield will drop away and the rover’s cameras will start to watch the approaching ground.
Since Mars’s atmosphere is paper-thin compared to Earth’s the parachute will only slow the rover down to about 200mph.
Perseverance will instead have to rely on the Skycrane – a jetpack-like powered descent platform armed with eight thrusters pointing at the ground.
NASA said: “Once it’s about 6,900ft (2,100m) above the surface, the rover separates from the backshell, and fires up the descent stage engines.”