Nasa's Curiosity rover has landed successfully on Mars and the most expensive and ambitious mission to reach the Red Planet is under way.
The \$2.5bn (£1.6bn) rover made a dramatic touchdown to cheers among staff at mission control some 154 million miles away.
Nasa said it had received a signal from the most hi-tech Mars explorer ever built after a plunge through the Martian atmosphere at 13,000 mph described as "seven minutes of terror".
Live: Follow the mission's progress
It slowed down with the help of a supersonic parachute before an elaborate sky crane powered by rocket blasters kicked in and, in a technological first, the rover - the size of a Mini - was lowered with nylon cables into a giant crater at 2 mph.
A video camera was set to capture the most dramatic moments - which would give people their first glimpse of a touchdown on another world.
"Touchdown confirmed," said engineer Allen Chen. "We're safe on Mars."
Minutes after the landing, Curiosity beamed back the first black and white pictures from the surface showing its wheel and its shadow, cast by the afternoon sun.
Over the next few days, it is expected to send back the first colour images.
There will also be several weeks of checks that all the equipment is working correctly. Then the six-wheel rover could take its first short drive and flex its robotic arm.
For the next two years it will drill into rocks and scoop up soil, exploring whether the planet's environment might once have supported life in the form of microscopic organisms.
Scientists agree Mars had water on its surface in ancient times, possibly as long as four billion years ago.
But precisely where, when and for how long there were lakes or oceans on Mars remains a mystery.
Scientists are also unsure whether, despite the presence of water, conditions were favourable or toxic to life.
Nothing could live on the radiation-cooked surface of Mars today, it is believed.
But some experts do not rule out the possibility of microbial bugs still living below the Martian surface.
After the successful landing, Nasa chief Charles Bolden said: "It's just absolutely incredible. It doesn't get any better than this."
President Barack Obama called the landing, which is eight years in the making, "an unprecedented feat of technology".
He tweeted: "I congratulate and thank all the men and women of Nasa who made this remarkable accomplishment a reality."
John Holden, from the US Office of Science and Technology Policy praised the "gutsy determination" of the team behind the mission.
"It will stand as an American point of pride far into the future," he said in a news conference after the launch, which saw the rover slice through the atmosphere of Mars at 13,000mph.
It is the space agency's seventh landing on Earth's neighbour - many other attempts by the US and other countries to zip past, circle or set down on Mars have failed.
Scientists hope the project will help prepare for a possible human mission to the planet. Mr Obama has called for such a mission by the 2030s.
Curiosity was launched in November 2011 from Cape Canaveral, Florida.