NASA's Perseverance rover fires up its descent stage engines as it nears the Martian surface in this illustration. This phase of its entry, descent and landing sequence, or EDL, is known as powered descent. Hundreds of critical events must execute perfectly and exactly on time for the rover to land safely on Feb. 18, 2021. The cruise stage separates about 10 minutes before entering into the atmosphere, leaving the aeroshell, which encloses the rover and descent stage, to make the trip to the surface. At about 6,900 feet (2,100 meters) above the surface, the rover separates from the parachute and backshell. At this point, the rover is joined to the descent stage, which functions as a sort of jetpack for the rover. The descent stage fires up its engines, flies to a reachable self-selected safe landing target, levels out, and slows to its final descent speed of about 1.7 mph (2.7 kph). It then initiates the skycrane maneuver about 12 seconds before touchdown, roughly 66 feet (20 meters) a