China launches flyby mission to the moon
A Long March 3C rocket launched a robotic Chinese space probe Thursday, setting the stage for a looping flight around the moon and a high-speed dash back to Earth to test technology and procedures needed for a planned robotic sample return mission in 2017.
Chinese news agencies reported the 184-foot-tall Long March booster blasted off from the Xichang Satellite Launch Center in Sichuan province, but the launch time and other details were not immediately available. The ascent was intended to put the solar-powered spacecraft, known in some quarters as Chang'e-5 T1, on a "free return" trajectory around the moon.
iCrossChina, a website associated with the Xinhua News Agency, reported "the test spacecraft separated from its carrier rocket and entered the expected orbit shortly after the liftoff." The report was attributed to the State Administration of Science, Technology and Industry for National Defense.
The uncrewed test vehicle is expected to swing around the moon and return to Earth in about a week, slamming into the atmosphere at nearly 7 miles per second, or roughly 25,000 mph. Touchdown is targeted for China's Inner Mongolia Autonomous Region.
"The mission is to obtain experimental data and validate re-entry technologies such as guidance, navigation and control, heat shield and trajectory design for a future touch-down on the moon by Chang'e-5, which is expected to be sent to the moon, collect samples and return to Earth in 2017," iCrossChina reported.
"It is the first time China has conducted a test involving a half-orbit around the moon at a height of 380,000 kilometers (236,000 miles) before having the spacecraft return to Earth."
A spokesman for the Chinese space agency said before launch the spacecraft will come in at an angle that will allow it to skip one or more times off the top of the discernible atmosphere, somewhat like a stone skipping across still water.
The idea is to use one or more atmospheric dips to slow the vehicle and avoid the most extreme temperatures generated by atmospheric friction.
The "skip re-entry" technique requires precise flight control and alignment. If the entry angle is too shallow, a spacecraft can skip off the atmosphere with enough velocity to return to space on a trajectory that would prevent another entry attempt. Conversely, if the entry angle is too steep, a spacecraft can be subjected to extreme braking forces and temperatures, possibly triggering the vehicle's destruction.
But the Chinese say if the technique works it will help pave the way for the proposed Chang'e-5 lunar sample return mission.
Jiang Jie, a rocket "expert" quoted by the Chinese news agency, said the lunar return flight represented an engineering challenge because "the mission requires that the rocket send the spacecraft to a fixed spot in space."
"Any inaccuracy will mean that the spacecraft will fail to enter the moon's orbit," she said.
The lunar flyby and return mission is the latest in a series of flights intended to perfect the technology and procedures needed for more advanced moon missions, including a sample return flight and eventual crewed missions. The Chang'e-1 spacecraft, launched in 2007, was the first Chinese craft to orbit the moon. Chang'e-2 followed suit in 2010.
More recently, the Chang'e-3 spacecraft landed on the surface of the moon in December 2013 and deployed a small rover, known as Yutu, or Jade Rabbit. It was the first spacecraft to successfully touch down on the moon since the Soviet Union's Luna 24 mission in 1976.
A backup spacecraft, Chang'e-4, was not launched, but presumably could be used in a future mission or some other capacity.
James Lewis, director and senior fellow at the Center for Strategic and International Studies, wrote in a blog hosted by the University of Nottingham that China's long-range goal is a crewed lunar landing mission. Not for military gain or direct economic benefit, but for national pride.
"The economic rationale for lunar exploration is dubious," he wrote. "Nor is there any military advantage to a lunar presence. However, it is hard to see how a global audience will interpret a Chinese landing on the moon while the U.S. sits on the sidelines as anything but the arrival of a new leading power.
"Discussions with NASA administrators and members of Congress suggest U.S. political leaders are at least for now, entirely indifferent to this, perhaps itself an indication of a waning global role."
For the Chinese, however, an aggressive lunar program provides "invaluable results."
"Two bombs and a satellite was Mao's way of demonstrating that China was also a great power," Lewis said. "For his successors, the manned (space) program plays the same role. Unlike the Apollo program, it may not demonstrate the superiority of the Chinese system to the world, but it successfully demonstrates it to the Chinese themselves, a conspicuous display of national power and wealth that asserts China's return to confidence and authority."
