NASA opened a new chapter in the history of interplanetary exploration Monday when its $2.5 billion nuclear-powered robot Curiosity beamed back pictures from the surface of Mars. The 1-ton mobile lab is the largest rover ever sent to Mars, and its high-speed landing was the most daring to date, using a rocket-powered sky crane to lower the six-wheeled vehicle gently to the Red Planet’s surface. “Touchdown confirmed,” said a member of mission control at NASA’s Jet Propulsion Laboratory as scientists hugged each other and the room erupted in cheers late Sunday. “We are wheels down on Mars. Oh, my God,” the NASA member said. A dusty image of Curiosity’s wheel, taken from a camera on the vehicle, confirmed the arrival of the rover and its sophisticated toolkit designed to hunt for signs that life once existed there. A second image arrived within seconds, showing the shadow of the rover on the Martian surface. The official landing time was 10:32 p.m. Sunday on the U.S. West Coast, according to a NASA statement. The nuclear-powered rover is now set for a two-year mission to explore the Red Planet, including a long climb up a mountain to analyze sediment layers that are up to a billion years old. When the landing was announced after a tense, seven-minute entry, descent and landing, NASA’s Jet Propulsion Laboratory filled with jubilation as the mission team cheered and exchanged Mars chocolate bars. President Barack Obama described the landing as “an unprecedented feat of technology that will stand as a point of national pride far into the future.” Charles Bolden, the NASA administrator, applauded all the other nations – such as France and Australia – whose scientists contributed to experiments on board the rover’s Mars Science Lab. Success had been anything but certain. NASA’s more recent rover drop-offs involved smaller craft that were cushioned with the help of airbags. In the final moments, the MSL craft accelerated with the pull of gravity as it neared Mars’s atmosphere, made a fiery entry at 21,240 kilometers per hour and then slowed with the help of a supersonic parachute. After that, an elaborate sky crane powered by rocket blasters kicked in, and the rover was lowered down by nylon tethers, apparently landing upright on all six wheels. Scientists do not expect Curiosity to find aliens or living creatures, but they hope to use it to analyze soil and rocks for signs the building blocks of life may have supported life in the past. The project also aims to study the environment to prepare for a possible human mission there.