WASHINGTON, Nov. 26 (Xinhua) -- A nuclear-powered U.S. rover lifted off on Saturday morning to help assess Mars' habitability, or whether the Red Planet is or ever was an environment able to support life.
The car-sized rover, atop an Atlas V rocket, blasted off at about 10:02 a.m. EDT (1502 GMT) from Cape Canaveral Air Force Station in Florida, NASA TV shows.
"Liftoff of the Atlas V with Curiosity, seeking clues to the planetary puzzle about life on Mars," said NASA commentator George Diller as the white rocket soared skyward.
The rover, nicknamed Curiosity, will journey for over eight months before touching down on Mars in August 2012, following a journey of 354 million miles (556 million km), using a jet pack and tether system to be lowered to the surface.
"A signal from the spacecraft ... has been received by officials on the ground," NASA announced an hour after liftoff.
At nearly a ton, the six-wheeled vehicle, also known as the Mars Science Laboratory, dwarfs all previous robots sent to the surface of the planet. It is about twice as long and more than five times as heavy as any previous Mars rover. Its 10 science instruments include two for ingesting and analyzing samples of powdered rock delivered by the rover's robotic arm.
During a prime mission lasting one Martian year -- nearly two Earth years -- researchers will use the rover's tools to study whether the landing region has had environmental conditions favorable for supporting microbial life and favorable for preserving clues about whether life existed.
Curiosity is the first instrument of its kind, and largest, most scientifically capable spacecraft ever destined for the surface of another planet. It is equipped with a generator that converts heat from the natural decay of a non-weapons-grade plutonium into electricity. The electricity will power rover systems and keep it warm in an environment where average temperatures are minus 64 degrees Fahrenheit.
The 2.5-billion-dollar project "is an incredibly important flagship mission for this agency ... as important as Hubble (space telescope)," observed Doug McCuistion, NASA's Mars exploration program director.
But the spacecraft also is two years late and almost a billion dollars over budget. Its launch comes at a time when NASA -- still struggling to find its way after the retirement of America's iconic shuttle fleet -- is anxious to exhibit its technological competence and prowess.
Curiosity will land near the base of a layered mountain three miles (five kilometers) high inside the Gale Crater on Mars. The crater spans almost 100 miles -- an area as large as Connecticut and Rhode Island combined.
Planetary geologists are intrigued because data from the U.S. Mars Reconnaissance Orbiter suggest the low-lying crater floor once was wet with water. Scientists also think the site might be rife with "organics" -- carbonaceous compounds that are key chemical building blocks for life.
Life on Earth emerges when liquid water is combined with a source of energy, such as sunlight, and carbon compounds.