But first it faces a long, 354-million-mile (570-million-kilometer) journey to get there, taking about eight and a half months before landing in August 2012.

The landing itself is set to be a spectacular affair. A ravioli-shaped capsule will open to expose the rover suspended by a "rocket backpack" that will fire its engines to lower the MSL to the ground.

The rover's six wheels and suspension system should "pop into place just before touchdown," NASA said. Then, the machine goes into "surface mode," using a series of cameras and a long robotic arm to investigate the Martian terrain.

"It is not your father's rover," said Doug McCuistion, director of the Mars Program at NASA headquarters in Washington, describing it as "truly a wonder in engineering... the best of US imagination, the best of US innovation."

NASA sees the latest rover as a midway point in a long journey of Mars exploration that began with the landing of the Viking spacecraft in 1976 and may culminate with a human mission there in the 2030s.

The venture is not meant to hunt for life on Mars, but rather for signs that it once may have existed there.

Any clues it can send back about the habitability of Earth's neighbor, the fourth planet from the Sun, and about the radiation levels there will be important to NASA as it devises future exploration missions.

"This mission has the purpose of setting us up for an eventual life detection mission," said Vasavada. "The goal of this mission is to look for habitable environments on Mars."

The landing site was announced in July, a day after the space shuttle Atlantis returned to Earth from its final mission to the International Space Station, marking the formal end of the 30-year US shuttle era.

The project is meant to last two years, but NASA hopes that like some of its other rovers in the past, Curiosity will outlive its expected potential.

The rover has such advanced instruments that scientists expect it will return much more data than any other to date.

"Viking did the best it could, but it could only see a couple of samples. MSL is going to look at tons of samples," said Pamela Conrad, deputy principal investigator of sample analysis at Mars.

Her experiment, a set of three spectrometers, is "designed to not only sniff the atmosphere and look for volatile species but to evolve gases from solid samples and then sniff those gases that come out," she said.

"Mars very easily could have produced life. Mars could very easily have evolved the complex chemistry that is necessary to be a habitable environment. And that information is still on Mars."

Of course, those involved in the launch have some jitters over the mission too because it is so complicated.

Russia's failure this week to get its pioneering Mars probe off on the right course also serves as a grim reminder of the dangers involved.

The unmanned Phobos-Grunt spacecraft lost its course to Mars and is stuck in low-Earth orbit, threatening to crash within days.

"The thing at the top of my concern list is what I don't know," said MSL project manager Pete Theisinger. "These things are very complicated, you test the heck out of them, but you can't test all their interactions."