A Cosmic SUV Blasts Off for Mars

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Terry Renna / AP

A rocket carrying NASA's Mars-bound Curiosity rover lifts off from Cape Canaveral, Fla., on Nov. 26, 2011

Nobody is going to call the Mars Curiosity rover "plucky." Back in 1997, plucky got used a lot, when NASA's first Mars rover, the microwave-oven-sized Sojourner, landed on the Red Planet and began toddling about. Spirit and Opportunity, a pair of golf-cart-sized Mars cars, followed in 2004 — and scrappy was the preferred adjective for them. On Saturday morning, the space agency's third-generation, SUV-sized Curiosity rover blasted off from Cape Canaveral, Fla., commencing a 255-day journey that should have it on the surface of Mars on Aug. 6, 2012. Prepare to hear the word rugged a lot.

The Curiosity rover is a bruiser of a vehicle by almost any measure — 9ft. 10 in. (3 m) long, and 7 ft. (2.1 m) tall, with a weight of 1,982 lb (899 kg). It's stuffed with instruments to study the chemistry, geology and possible biology of Mars, and will do that work with the aid of a robotic arm equipped with drills and scoops, and multiple cameras — including one that will operate at human-eye level, giving the images it sends back a familiar frame of reference that will make scales and perspectives easier to understand.

NASA Launches Curiosity Rover to Mars

The ship cost a cool $2.5 billion to design, build and launch, and that price tag is one reason NASA will be especially anxious until it arrives safely next summer. For all the remarkable things Curiosity should do when it does touch down, it's the method NASA has developed to get it there that is especially ingenious.

Like all Mars missions, Curiosity blasted off in a precise window in which the ever changing distance between Mars and Earth affords it the quickest trip possible. At the moment of launch, the blue planet and the red planet were 127 million miles (205 million km) apart, which is less than a third of the maximum distance they reach during their differing orbits around the sun. That's still a lot of cosmic real estate to cover though, enough that when the rover does land, any signal beamed from Mars to Earth or Earth to Mars — traveling at light speed — will take nearly 14 minutes to arrive.

For the previous three rovers, the business of actually landing on the surface — remarkable as it was — had a certain Ringling Brothers quality to it. Sealed inside a descent shell, the Mars cars would plunge through the atmosphere, aided by braking rockets, parachutes and simple air resistance until their rate of descent had slowed sufficiently, at which point they would simply fall the rest of the way, swaddled in a cocoon of inflatable air bags. The rovers didn't so much touch down as bounce down, bounding and rolling across the surface until they came to a stop and the bags could be shed.

There will be no such ignominious arrival for Curiosity. Entering Mars's tenuous atmosphere about 81 miles (131 km) above the ground, it will free-fall until it's about 7 miles (11 km) up and descending at 900 m.p.h. (1,448 km/h). At that point, parachutes will be deployed, and shortly after that, braking thrusters will fire. Finally, about 66 ft. (20 m) up, long nylon cables will spool out of the hovering descent shell, lowering the rover gently to the ground. As soon as this so-called sky crane has done its work, the descent shell will kick its engines once more, tossing itself out of the way and crash-landing at a safe distance.

"Basically, this thing is a Transformer," says launch director Omar Baez, a veteran of the previous three rover missions. "It starts as a pancake, it opens up and you've got six wheels, you've got mass, you've got all kinds of protuberances coming out of it, and it's all got to work right the first time."

Assuming it does, Curiosity will get straight to business (the local Mars time at the moment of arrival, according to the prime mission timeline, will be equivalent of 3 p.m., so there'll be no excuse for not putting in a full day). The rover's landing site is the Gale Crater, along the equator in the eastern Martian hemisphere. The crater is a massive formation — about the size of Rhode Island and Connecticut combined — and assuming Mars was once as wet as scientists are all but certain it was, much of that square mileage would have been underwater, making it a good place to look for the residue of life. Conditions are a little less hospitable to biology now, of course, with the temperature never getting above freezing, and often plunging as low a -130°F (-90°C).

If all goes well, Curiosity will survive those punishing conditions for one Martian year (98 weeks), but since previous rovers have dramatically exceeded their minimum life spans, there is reason to believe Curiosity will too. "I bet there's going to be some knockout science and some great pictures and a great experience," says Baez. If the rover's little brothers are any indication, that's a bet worth taking.