After a planned launch on Nov. 26, 2011, the Mars Science Laboratory (MSL), aka Curiosity, will reach Mars in August, the third Red Planet landing since the rovers Spirit and Opportunity touched down in 2004. Those machines were impressive, but they stand in the large shadow of Curiosity, which?at 10 feet long and 1984 pounds?is twice as long and five times as heavy as its predecessors. "The thing about MSL is how much bigger it is," Diana Blaney, a mission co-investigator, says. "The instruments are much more complex, plus we're on a mobile platform."
Curiosity picks up where the 2008 Mars Phoenix Lander left off; that mission proved the existence of water on Mars and discovered perchlorate, a potential food source for microbes. Curiosity hopes to show there's organic material on Mars, a requirement for habitability. "If you have sources of food and water and organic material, you could say, you have the building blocks of life," Curiosity co-investigator Nilton Renno says.
The Power Source
Engineers hope Curiosity will rove for at least two years, relying on a unique power source. NASA is forgoing solar panels of the past, and instead packing the rover with nuclear-powered batteries called Radioisotope Thermoelectric Generators (RTGs). Drawing energy from the natural decay of plutonium-238, RTGs produce almost five times more power than solar panels on previous rovers. They also perform well in conditions that are dusty or without sunlight.
The SAM
Among its other functions, the Sample Analysis at Mars (SAM) suite features a remote-sensing device capable of targeting pinhead areas on rock formations from up to seven meters away. ChemCam, as it is known, can then shoot a laser beam at the rock and analyze the vaporized material using a light-reading spectrograph. "It has the potential to really study chemical evolution at a different scale than before," co-investigator Blaney says. "We'll be able to map composition at a fine scale." The SAM suite consists of three instruments. The aforementioned tunable laser beam, a Quadrupole Mass Spectrometer (QMS), and a Gas Chromatograph (GC). This scientific trinity will work to analyze samples on the surface, inside Martian boulders and below ground, searching for the organic building blocks of life.
Wheels and Actuators
At 20-inches in diameter, Curiosity's wheels are larger than those of an average car?and twice the size of those on the Spirit and Opportunity rovers. To maneuvering over rough Martian landscape, each wheel features high-traction cleats and a dedicated motor. The front and rear wheels actually have two motors apiece, enabling independent steering. All of this makes for impressive handling: Curiosity can turn 360 degrees in place. But its impressive mobility came at a price. A snafu in the development and testing of the actuator motors caused a two-year launch delay, and added $560 million to the cost of building and deploying the rover.
The Landing System
Unlike its smaller roving cousins, which used airbags to cushion their entry on Mars, MSL is far too large and heavy (nearly a ton) to bounce to safety on Mars. Engineers devised a unique, only-in-the-dreams-of-a-NASA-engineer, precision system based on a rocket-powered backpack called Sky Crane. In the initial stages of descent, a parachute 165 feet in diameter deploys. The parachute jettisons, and rockets kick in, providing upward thrust to further slow the rover's descent. Radar detects the landing surface and orients the crane upright. Hovering with the aid of the rocket streams, the crane lowers the rover to the surface on cables, then releases Curiosity to begin its amazing mission.
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