Editing Mars Science Laboratory (section)

==== {{anchor|Sky crane landing}} Sky crane ====
{{Main|Sky crane (landing system)}}
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[[File:675608main_edl20120809-full.jpg|thumb|Entry events from parachute deployment through powered descent ending at sky crane flyaway]]
[[File:593484main pia14839 full Curiosity's Sky Crane Maneuver, Artist's Concept.jpg|thumb|Artist's conceptIon of ''Curiosity'' being lowered from the rocket-powered descent stage]]

For several reasons, a different landing system was chosen for MSL compared to previous Mars landers and rovers. ''Curiosity'' was considered too heavy to use the airbag landing system as used on the [[Mars Pathfinder]] and [[Mars Exploration Rover]]s. A legged lander approach would have caused several design problems.<ref name="spaceflightnow.com_1"/> It would have needed to have engines high enough above the ground when landing not to form a dust cloud that could damage the rover's instruments. This would have required long landing legs that would need to have significant width to keep the center of gravity low. A legged lander would have also required ramps so the rover could drive down to the surface, which would have incurred extra risk to the mission on the chance rocks or tilt would prevent ''Curiosity'' from being able to drive off the lander successfully. Faced with these challenges, the MSL engineers came up with a novel alternative solution: the sky crane.<ref name="spaceflightnow.com_1"/> The sky crane system lowered the rover with a {{convert|7.6|m|foot|abbr=on}}<ref name="spaceflightnow.com_1"/> tether to a soft landing—wheels down—on the surface of Mars.<ref name="EntryDescentLanding"/><ref name="scientificamerican"/><ref name="Mars rover lands on Xbox Live"/> This system consists of a bridle lowering the rover on three nylon tethers and an electrical cable carrying information and power between the descent stage and rover. As the support and data cables unreeled, the rover's six motorized wheels snapped into position. At roughly {{convert|7.5|m|abbr=on}} below the descent stage the sky crane system slowed to a halt and the rover touched down. After the rover touched down, it waited two seconds to confirm that it was on solid ground by detecting the weight on the wheels and fired several [[pyrotechnic fastener|pyros]] (small explosive devices) activating cable cutters on the bridle and umbilical cords to free itself from the descent stage. The descent stage then flew away to a crash landing  {{convert|650|m|foot|abbr=on}} away.<ref>{{cite web |url=http://www.nasa.gov/mission_pages/msl/news/msl20120807.html |title=Orbiter Images NASA's Martian Landscape Additions |access-date=August 9, 2012 |date=August 8, 2012 |work=NASA}}</ref> The sky crane concept had never been used in missions before.<ref name="youtube"/>