Called Curiosity, the rover's mission will be to search for clues to whether Mars ever had—or still has—environments favorable for life.
The compact car-size, 2,000-pound (900-kilogram) robot is due to lift off Saturday from Cape Canaveral in Florida aboard an Atlas V rocket at 10:02 a.m. ET. If anything delays tomorrow's lift-off, NASA has until December 18 to attempt the launch.
If the launch goes smoothly, the rover will be the first NASA craft to land on another planet using an innovative design dubbed the sky crane, which will lower the rover to the surface on cables in a similar fashion to a helicopter lowering a payload.
NASA needed a new landing system because Curiosity is nearly twice the size and five times heavier than its cousins, the Mars rovers Spirit and Opportunity, which landed in 2004 encased in protective airbags.
With such a hefty machine, airbags wouldn't be able to safely cushion the new rover's fall.
"While we have our fingers crossed that everything at the launch goes well, it's really when we get to Mars next summer that we begin to hold our collective breath," said Rob Manning, chief engineer for the new rover at NASA's Jet Propulsion Laboratory in Pasadena, California.
(Related pictures: "Five 'Cursed' Mars Missions.")
New Way to Land on Mars
Upon arrival at Mars next August, the spacecraft carrying Curiosity will enter the red planet's atmosphere at an initial speed of 13,000 miles (21,000 kilometers) an hour.
Watch an animation of the Mars rover's projected landing and mission highlights.
Once atmospheric friction has slowed its fall to about 1,000 miles (1,600 kilometers) an hour, the craft will deploy parachutes to further slow its descent.
After popping off its heat shield, the rover will use landing radar to orient itself to the ground. Then, about a mile (1.6 kilometers) above the Martian surface, the sky crane—with the rover attached—will detach from the spacecraft's backshell and fire retrorockets.
Once it's traveling at less than 2 miles (3.2 kilometers) an hour, the crane will gently lower the rover on nylon cords until the robot's wheels sense the Martian surface, at which point the sky crane will detach from the rover and fly away.
"Because there will be a near 14-minute time delay for the signal to reach us here on Earth, due to the vast distances between our planets, [Curiosity] will have to complete the entry, descent, and landing phase completely autonomously," Manning said.
"No doubt it will be some anxious moments, since all we can do is wait and watch."
Mars Rover to Need Daily Naps
Ultimately, the goal is to land Curiosity within a 25-mile-wide (40-kilometer-wide) ellipse inside a 96-wile-wide (155-kilometer-wide) impact basin near Mars's equator called Gale Crater.
The crater appears to have once housed a lake fed by an adjoining ancient river. In addition, Gale Crater features a three-mile-high, gently sloping mountain near its middle with exposed layers of sediments and what seem to be water-bearing minerals.
Like a chemistry lab on wheels, Curiosity will study the crater using a suite of 11 science instruments, including two high-definition cameras and a rock-vaporizing laser mounted on a seven-foot-high (two-meter-high) mast.
Also, the rover's 6-foot-long (1.9-meter-long) robotic arm is outfitted with a rotating suite of tools and sample-collection devices, including a power drill.
Loaded with all this gear, Curiosity is the most power-hungry robot yet to explore the red planet.
So unlike the solar-powered Spirit and Opportunity, the new rover is equipped with an onboard plutonium power plant—the Radioisotope Thermoelectric Generator—that's able to produce 100 watts around the clock.
Still, Curiosity will need to go into "sleep" mode on a daily basis to recharge its batteries so it can carry out its duties.
"While Curiosity can walk and chew gum at the same time, it can't keep it up for very long before it has to stop and rest, because of this energy limitation," Manning said.
If all goes as planned, the plutonium generator will give Curiosity enough electrical power to explore its new home for at least one Martian year, equal to two Earth years.
Reading Mars's Watery Past
NASA scientists believe water may have flowed through Gale Crater for a significant length of time about three billion years ago, making it an ideal spot to search for traces of habitability.
"The beauty of our landing site is that there is a mountain at the center of this crater which has a stack of sedimentary materials, of which our orbital data says that local environmental conditions might have been habitable early on in Mars history," said Richard Zurek, chief scientist for NASA's Mars exploration program.
"The basic essentials for life may have not only started within Gale Crater but may have persisted and might have been preserved today in the surrounding rocks."
Unlike Spirit and Opportunity, which could only scratch the surfaces of rocks, Curiosity will be able to drill a few inches into a rock, scoop up the powdered material, and run it through onboard instruments.
The rover's experiments will not only look at the mineralogy of the rock but will also search for organic materials possiby left behind by life-forms.
And by traveling up the slope of the mountain, the rover will be able to examine the different rock layers and trace the history of Mars's watery past.
"We are talking about a stack of material that is hundreds of meters thick that is a record of history that is a hundred million years [long]," Zurek said.
"In that stratified stack of rocks ... we hope we can just read through time—that's what makes it such an exciting site," he said.
In addition, he said, "we love to think about the possibilities, but Mars has surprised us at every turn. Even if some of what we thought was true, we [usually] find new questions."