The biggest, most advanced robotic machine ever built to explore Mars is poised to launch Saturday on a mission to find places where life may have existed, or may live on today, NASA said this week.

The $2.5 billion Mars Science Laboratory has been described as a "dream machine" by US space agency scientists because of its state-of-the-art cameras, robotic arm, mobile chemistry lab and rock-zapping laser beam.

The launch of the 1,982-pound (899-kilogram) vehicle is set for November 26 at 10:02 am (1502 GMT) from Cape Canaveral Air Force Station in Florida.

After a nearly nine month journey to the red planet, the unmanned rover, nicknamed Curiosity, should make a spectacular rocket-powered sky crane landing before rolling off to scour Earth's nearest neighbor for interesting rocks.

"It is doing a real estate assessment. Where are those good schools on Mars? Where might there be microbes living or some type of life?" said Mary Voytek, director of the NASA Astrobiology Program.

The rover's landing spot on August 5, 2012 will be Gale Crater, chosen because it contains a three-mile (five-kilometer) high mountain and is believed to harbor low-lying layers of sediment and clay that may have held water, and therefore, life.

"This looks like a very promising place, that it had water sometime in its past that would make it a habitable place," said Michael Meyer, lead scientist for NASA's Mars Exploration Program.

On Earth, microbial life exists everywhere that water does, so scientists are hopeful the same may be true of Mars.

In August, NASA said it had found evidence of flowing salt water on steep Martian slopes, which if confirmed would be the first discovery of active liquid water on the red planet.

The data appeared to show briny water moving beneath the surface and was gathered by the Mars Reconnaissance Orbiter. However, Curiosity is not exploring those same areas and so will not be in a position to confirm the sighting.

No liquid water has been found on Mars, though ice has been discovered at the poles.

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.

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

"We are basically reading the history of Mars' environmental evolution," said John Grotzinger, project scientist for Mars Science Laboratory at the California Institute of Technology.

"We start at the bottom where the clays are, we go to the sulfates, and we come up and go to the top of the mound and get rocks we think were formed in largely non-water bearing environments representing the drier, more recent phase of Mars."

One of the key instruments on board is a joint French-US project called the Chemistry and Camera investigation, which can emit a laser beam with the energy of a million light bulbs and tell scientists what makes up a Martian rock.

"It's like an arm that can reach out up to 25 feet (eight meters) away, brush something off, analyze it, actually look at the weathering surfaces and the interior of the rock at the same time," said Roger Wiens, principal investigator.

The rover's robotic arm, meanwhile, can drill into the ground or into rocks to create a powder, and a mobile chemistry lab that can sift through the powder and tell scientists back on Earth what it contains.

"Do we anticipate that we will learn a whole lot about Mars? Absolutely. Do we know what specifically that will be? No clue," said Pam Conrad, deputy principal investigator, Sample Analysis at Mars, MSL.

"But we will learn more than we presently know about the Martian environment."

The equipment must first travel a long journey of 354 million miles (570 million kilometers), and if all goes as planned, NASA hopes the rover will survive for two years or longer.

Of course, those involved in the launch have some jitters over the mission because it is so complicated, and because a series of Russian, US and European efforts have failed to land as expected on Mars in past decades.

Russia's failure earlier this month to get its pioneering Mars probe -- the unmanned Phobos-Grunt spacecraft -- off on the right course also serves as a reminder of the dangers involved.