The Mars rover Curiosity successfully landed on the planet early on Monday morning, in an event watched online by millions of people.
The 900kg vehicle, more properly known as the Mars Science Laboratory (MSL), landed near the foot of a mountain in the Gale Crater at 6.32am BST, roughly 36 weeks after it left Earth. Curiosity's mission is to look for signs of past habitability in the crater, ahead of potential future manned missions to the Red Planet.
"Today, the wheels of Curiosity have begun to blaze the trail for human footprints on Mars," NASA administrator Charles Bolden said in a statement. "Curiosity, the most sophisticated rover ever built, is now on the surface of the Red Planet, where it will seek to answer age-old questions about whether life ever existed on Mars — or if the planet can sustain life in the future."
The first image returned from Curiosity is that of its own shadow on Mars's rocky surface. That black-and-white shot will be followed by colour imagery in the next few days. NASA has also published photos of its staff's jubilation at the successful landing.
Curiosity touched ground after what the scientists called The Seven Minutes of Terror — namely the seven minutes of slowdown between the spacecraft hitting Mars's atmosphere at 20,000 kilometres per hour and making a gentle landing on the surface.
At the various stages of the landing, Curiosity broadcast signals back to the Canberra Deep Space Communication Complex (CDSCC) in Australia, which was monitoring the situation on behalf of NASA. Some signals came directly, while others were relayed through NASA's Mars Odyssey spacecraft, which already orbits the planet.
"The Seven Minutes of Terror has turned into the Seven Minutes of Triumph," NASA associate administrator for science John Grunsfeld said. "My immense joy in the success of this mission is matched only by overwhelming pride I feel for the women and men of the mission's team."
NASA is still getting results from previous missions to Mars. The Opportunity rover is still sending back images, but its twin Spirit was . Those rovers were sent up in 2003, and were expected to last only a few months on the Martian surface.
Curiosity's scientific instruments have 15 times the mass of those carried aboard Spirit and Opportunity, making it necessary for the vehicle to be five times as heavy and twice as long as either of its forebears.
The MSL will use a laser to probe the composition of rocks, then drill out and scoop up soil and powdered rock samples for analysis by its laboratory instruments. NASA already reckons that the lower layers of the nearby crater-mountain include clay and sulphates — a suggestion that Mars used to be at least partially wet.