NASA's Mars Science Laboratory rover, to be launched in 2009, may touch down on the surface of the Red Planet using a method modelled on the Sikorsky S-64 Skycrane external-lift helicopter. The US space agency wants to ensure the rover will make a "wheels down" landing on Mars that will allow it to begin operations immediately, with no need for airbags - such as those used to cushion the Mars Exploration Rover landings - or unfolding solar panels, antennas and other equipment.

The skycrane concept, which is in the early stages of study, would use a spacecraft that will make a rocket-powered descent to a hover altitude of 16ft (5m), allowing the rover to slip slowly down a deployed tether and be placed gently on the surface. The skycrane craft would then manoeuvre laterally and crash-land safely away from the rover. NASA must weigh the risks of the skycrane method, compared with the proven airbag system, against the benefit of ensuring the rover will be ready for immediate operations on the surface.

Source: Flight International