AMID a puff of lunar dust, Chang’e-3 touched down on the moon at 9:12 p.m. Saturday, making China the third nation to land a craft on the celestial body.

    Scientists erupted in cheers at the command center in Beijing as a computerized display showed the probe had landed in a flat plain known as Sinus Iridum, Latin for Bay of Rainbows, an unvisited area in the moon’s north.

    Lan Xiaohui, designer of Chang’e-3’s thrust engine, told CCTV “the landing was perfect.”

    The Chang’e-3 began its approach from an orbit about 15 kilometers above the moon. The final descent was controlled with the main engine and 28 small thrusters, which took the craft from a speed of 1.7 kilometers per second to almost zero within a few minutes.

    Instruments on board allowed the probe to analyze the landing area and make adjustments from 100 meters away.

    Four meters above the surface, the engine was switched off, and the Chang’e-3 went into free fall. Upon touching down, the on board camera snapped an image of its surroundings and sent it back to operators at the Beijing Aerospace Control Center.

    It was the first soft landing on the moon in nearly four decades. The United States crashed three spacecraft before it succeeded with the technique, while the former Soviet Union took 11 attempts. China hit the bull’s eye on the first try.

    Chinese space scientists and engineers were holding their breath throughout the lengthy process with fear that the force of impact on landing and the fine lunar dust might damage some critical electronic or mechanical parts.

    Zhang Tingxin, chief commander of the rover system, told China Central Television that the separation of the rover from the probe was “smoother than expected.”

    He gave the biggest credit to the automatic landing system on Chang’e, which found and landed the spacecraft on an almost entirely flat ground without any human intervention.

    “The landing vehicle was in a very good position. After the touch down, it was standing almost entirely vertically with only one or two degrees of tilt,” he said.

    Lan said he was most concerned about the final 30 meters, as the spacecraft searched for the best landing spot. But the engines did a “great job,” he said.

    Liu Jianjun, a lunar geologist with the National Astronomical Observatories, said the level area would be good for the rover’s exploration. “We have seen few shadows on the photos sent back by the landing camera. The fewer shadows, the flatter the terrain and the better for the mission,” he told CCTV.

    Before touch down, the probe hovered and scanned the landing area, and moved horizontally, to secure the safest spot.

    This procedure, to avoid any cracks or bumps, had not been used previously in a lunar landing and placed a high demand on rockets, sensors and software.

    Wu Weiren, chief designer of the lunar exploration project, told Xinhua that Chang’e-3 had gone through the most challenging phase of the landing by itself, with “almost zero” human interference.

    “The biggest risk was that all the critical devices of this mission are newly developed, and there was uncertainty about the terrain of the landing zone,” he said.

    Chang’e-3 is part of the second phase of China’s lunar program, which includes orbiting, landing and returning to Earth. It follows the success of the Chang’e-1 and Chang’e-2 missions in 2007 and 2010, respectively.

    Chang’e-3 is the world’s first soft-landing of a probe on the moon in nearly four decades. The last such soft-landing was carried out by the Soviet Union in 1976.

    (SD-Agencies)