Curiosity will be "the largest and most complex piece of equipment ever placed on the surface of another planet," said Doug McCuistion, director of NASA's Mars exploration program.
Ten feet long, 9 feet wide, and 7 feet tall at its mast, Curiosity is about twice the size of previous rovers Spirit and Opportunity, weighs 1 ton and is loaded with 10 science instruments. Its formal name is Mars Science Laboratory, or MSL.
In a spacecraft first, Curiosity will be lowered to Mars' surface by a jet-pack and a tether system similar to the sky cranes used by helicopters to insert heavy equipment in inaccessible spots on Earth. It's a kind of precision landing that officials say will benefit future explorers on Mars.
The rover is scheduled to arrive at the mineral-rich Gale Crater in August, 81/2 months after embarking on the 354 million-mile voyage aboard an Atlas V rocket.
It's a treacherous journey to Mars, and the road is littered with failures. In all, more than three dozen missions have aimed over the decades at the most Earthlike planet known, but fewer than half have succeeded. Of this flotilla, only one lander is still working on the dry, barren, cold surface - Opportunity - and only three craft still are observing the planet from orbit.
Curiosity is the capstone of what NASA calls the year of the solar system. A spacecraft is in route to Jupiter after lifting off in August from Cape Canaveral, and twin lunar probes launched in September will arrive at the moon New Year's weekend.
A huge crowd - 13,500 invited guests - is expected for Curiosity's Thanksgiving-weekend send-off.
There will be more anxiety than usual over the launch. Curiosity holds 10.6 pounds of plutonium, more than enough to power the rover on the Martian surface for two years. A nuclear generator won out over solar energy because it allows for a bigger workload and more flexibility. The plutonium is encased in several protective layers in case of a launch accident.
Despite all its fancy upgrades, Curiosity will go no faster than the one-tenth-mile-per-hour logged by past Martian rovers. But it is expected to venture more than 12 miles during its two-year mission.