Mars Science Laboratory represents the first use of a "soft-landing" technique employed at Mars. The sheer mass of Mars Science Laboratory prevented engineers from using the familiar airbags to deliver their rover safely to the martian surface. As rovers become more capable and carry more instruments, they become larger. So, in order to accommodate this advanced mission, engineers designed a sky-crane method that will lower the rover to the surface.
After the parachute significantly slowed the vehicle and the heatshield (that protected the rover during entry) separated, the descent stage separated from the backshell. Using four steerable engines, the descent stage slowed the nested rover down even further to eliminate the effects of any horizontal winds. When the vehicle slowed to nearly zero velocity, the rover was released from the descent stage. A bridle and "umbilical cord" lowered the rover to the ground. During the lowering, the rover's front mobility system was deployed so that it was essentially ready to rove upon landing. When the on-board computer sensed that touchdown was successful, it cut the bridle. The descent stage then pitched away from the rover and powered away at full throttle to a crash-landing far from Mars Science Laboratory.