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How the Mars Curiosity Rover Works


A Noiseless, Patient Rover
Because of its size, Curiosity couldn't do an airbag-assisted landing. Instead, the Mars Science Laboratory used the sky crane touchdown system illustrated here, which is capable of delivering a much larger rover onto the surface of Mars.
Because of its size, Curiosity couldn't do an airbag-assisted landing. Instead, the Mars Science Laboratory used the sky crane touchdown system illustrated here, which is capable of delivering a much larger rover onto the surface of Mars.
Image courtesy NASA/JPL-Caltech

Within Mars, rising higher than Mount Rainier towers above Seattle, stands a sediment mountain 3 miles (5 kilometers) high. Composed of layers of minerals and soils -- including clays and sulfates, which point to a watery history -- these layers will provide an invaluable map of Martian geological history [sources: Siceloff; Zubritsky].

Past water would have flowed toward and collected in Gale's lowlands, making it a likely repository for the remains of streams, pools and lakes, and therefore an ideal place to find evidence of Mars's past habitability.

Like Walt Whitman's "noiseless patient spider," Curiosity will one day soon stand isolated on a promontory, sending back data from which its mission controllers will decide "how to explore the vacant vast surrounding." Its spidery resemblance does not end with poetic license or even its spindly, jointed legs, however; it extends to the spiderlike way the rover landed on the Martian surface.

Before we unravel that, however, let's look at the rocket-assisted jump the craft made when it first reached Mars.

When the spacecraft carrying Curiosity swung into the Martian atmosphere 78 miles (125 kilometers) above the ground, it steered and braked through a series of S-curves like those used by the space shuttles. During the minutes before touchdown, at around 7 miles (11 kilometers) up, the craft popped a parachute to slow its 900 mph (1,448 kph) descent. It then ejected its heat shield from the bottom of the cone, creating an exit for Curiosity.

The rover, with its upper stage clamped to its back like a turtle shell, fell clear of the cone. A few moments later, the upper stage's rim-mounted retro rockets blasted to life, stabilizing the pair into a hovering position about 66 feet (20 meters) above the surface; from here, the upper stage acted as a sky crane, lowering Curiosity like a spider on silk. Once the rover was safely on the ground, its tether was cut, and Curiosity set off on its journey [sources: NASA; JPL].

Shortly before touchdown, the Mars Descent Imager took high-definition color video of the landing zone. This footage aided with landing and provided a bird's-eye-view of the exploration area for researchers and mission specialists back home. Another array of instruments, the Mars Science Laboratory Entry, Descent and Landing Instrument Suite, will measure atmospheric conditions and spacecraft performance. NASA will use this data when planning and designing future missions.

The novel landing system was more complicated, but also more precisely controlled, than any before, enabling mission planners to bull's-eye the long-desired target of Gale Crater. Landing within Curiosity's 12-mile (20-kilometer) target area within the crater would have been impossible for Spirit and Opportunity, which needed five times as much area when bouncing down in their space-age bubble wrap. This success opened up a slew of desirable sites, including steep-walled craters previously off-limits due to their tricky terrain.

Curiosity will also lay the groundwork for future missions, just as previous Mars jaunts made the new rover's expedition possible. Such missions could include scooping up rocks and flying them back home, or carrying out more far-reaching surface surveys, seeking evidence of Martian microbial life and its key chemical ingredients [source: NASA].

Now that we've landed safe and sound, let's take a look at what kind of equipment comes standard with the Mars Science Laboratory package.