Man in the machine

FOR the past nine years Scott Maxwell has worked on Mars. Or at least as close to it as is possible on Earth. This, it turns out, is Pasadena, California, home to NASA's Jet Propulsion Laboratory (JPL), which manages many probes, rovers and satellites for America's space agency. From there Mr Maxwell has driven three Mars vehicles: Spirit and Opportunity,Vertical shaft impact crusher twins dispatched in 2004 as part of the Mars Exploration Rover (MER) mission, and, more recently, Curiosity, which touched down on the planet last August carrying Mars Science Laboratory (MSL).Of course, you don't just take Curiosity out for a spin. Mr Maxwell, who helped develop the driving software for the MERs and later became their principal pilot before moving on to direct the newer set of wheels, explains that you need to put yourself in the rover's head. This lets you picture and plot moves before typing the computer code that is then beamed to the vehicle. On February 8th, he announced a few days ago, he plans to shed the robot suit and resume his human life, but not before having trained other chauffeurs in the same mental gymnastics.

The MSL driving team comprises 16 operators, divvied up into groups specialising in mobility, moving the arm (to blast rocks with a laser to study their chemical composition and to take close-up photos) and managing the turret on the arm that houses a percussive drill. They drive the rover and deploy its instruments as instructed by the mission team, which meets each Earth day to decide, through consensus, where it should go on the following Mars day, or sol, and what science it should perform there.Mobile crusher

Mr Maxwell,Self-drive to China a member of the mobility team, demonstrates to your correspondent how he might move his hand in sympathy with the rover's multi-jointed wheels to think through the physical sequence. A computer scientist, Mr Maxwell then plots the route in software he developed that translates the driving sequence into commands that the on-board computer understands.travel to xinjiang But before instructions are beamed to one of two NASA satellites orbiting Mars, and thence to Curiosity, Mr Maxwell and his colleagues feed them into a simulator. Curiosity's several pairs of cameras―Mr Maxwell jokes that it has "more eyes than a potato"―provide stereoscopic images that let the boffins at JPL get a feel for the Martian landscape.metal machining This makes it easier to plan and test movements on a computer.