The Mars Science Laboratory (MSL) mission to the Red Planet features the largest rover ever built, aptly named Curiosity. With dimensions comparable to those of a small car, the new robot is currently undergoing preparation stages at NASA's Jet Propulsion Laboratory, in Pasadena, California, on schedule for its 2011 launch date. The American space agency recently announced that the heat shield for the rover, which is undoubtedly the largest shield ever to be sent with an unmanned mission, was finally complete and awaiting to be mated with the finished exploration vehicle.

“The Mars Science Laboratory aeroshell is the most complex capsule to fly to Mars. The design had to address the large size and weight of the rover, the largest ever sent to Mars, and the requirement for landing at a more-precise point on Mars,” the Lockheed Martin Space Systems Co. Program Manager, Rich Hund, explained.

The 15-foot (4.5-meter) -wide aeroshell is even larger than the one the Apollo 11 mission to the Moon used when reentering Earth's atmosphere. It easily outclasses those of missions such as MER, Viking, or the Phoenix Mars Lander, in terms of size and complexity.

As a reference point, the twin Martian rovers and MER components, Spirit and Opportunity, were protected by an 8.5-foot (2.6-meter) -wide shield, whereas the Apollo spacecraft only had a 13-foot (some 4-meter) -wide shield. In order for Curiosity to be able to withstand the 3,800 degrees Fahrenheit (2,100 degrees Celsius) that form on the outside of the aeroshell when it enters the thin Martian atmosphere, the shield was plated with Phenolic Impregnated Carbon Ablator tiles, which are a new kind of shield components.

They will undergo testing on Mars for the first time with the MSL. The descent of the craft will most likely be filmed by the Mars Reconnaissance Orbiter (MRO), though a final landing point has yet to be determined.

The shield is but the first part of NASA's intricate mission of landing the automobile-sized rover on the Martian surface. Once it's no longer needed, the shield and its extensions will be jettisoned, and the craft carrying the MSL will begin a powered descent towards the surface. A “sky crane” will land the rover on Mars using cables and wires, and it will then take off and crash somewhere else.

After the heat shield is disposed of, the only things between Curiosity and annihilation will be a few parachutes, which have the sole purpose of decelerating its speed until the crane's thrusters are enough to overcome the planet's gravity, Space informs.