Entry, Descent & Landing

The subsystem — and the few dramatic minutes — that gets a spacecraft from the top of an atmosphere to a safe landing: a heat shield to survive entry, a parachute or thrusters to slow down, and legs or airbags to touch down.

The ablative or reusable shield that protects a spacecraft from the searing heat of atmospheric entry, where air violently compressed ahead of the vehicle's bow shock can reach thousands of degrees (the heating is dominated by shock compression, not friction). Ablative shields char and carry heat away as they erode.

The decelerator that slows a spacecraft in an atmosphere after the heat shield has done its work — from the supersonic parachutes of Mars landers to the splashdown chutes of crew capsules.

The thrusters, legs, or airbags that manage the final touchdown — from the sky-crane of the Mars rovers to the propulsive landings of crew and booster vehicles.