March 25, 2013
Credit: Long March 3C: CMSEO
Somewhere in China, technicians are struggling with their machine tools, trying to make huge but perfectly shaped metal structures—perfectly round, and with complex internal shapes to withstand the loads of an 800-ton rocket accelerating toward orbital velocity. The technicians have routinely succeeded in making such structures before, but none so big. As these people are all too aware, the bigger they are, the harder they are to get right.
Upon the efforts of these technicians rests much of the future of China's space efforts. Modules of a planned space station will need the rocket, Long March 5, that will be built with these structures. So will a range of oversize spacecraft, presumably including powerful reconnaissance satellites, for which China is building a special plant. Even China's next-generation commercial communications satellite bus is under development for the world market, based on the assumption that Long March 5 will be available. This Long March is the long pole in the Chinese space tent.
It will be available—just not as soon as expected, says Liang Xiaohong, deputy head of the China Academy of Launch Vehicle Technology (CALT). Long March 5, to be the heaviest and most technologically difficult member of China's new space-launcher family, has been delayed by at least another year, to 2015, due to challenges in making its structure, Liang says.
Another launcher, which would improve China's ability to loft military satellites on short notice thanks to its solid fuel, is due to fly in 2016 under the designation Long March 11, while the industry is also preparing to seek funding for an enormous Moon rocket, says the official.
Chinese space engineers have long recognized the challenge that is holding up Long March 5, which will have a hydrogen-fueled core first stage and be comparable to the U.S. Delta IV. Repeatedly, when asked which aspect of their program most concerned them, they have noted to Aviation Week the difficulty in precise manufacturing of the launcher's 5-meter-dia. (16.4-ft.) body. Propulsion, which usually ranks high on the list of space-launcher technology troubles, is not mentioned as a problem, presumably because the Long March 5 engines were fully developed years ago.
“Our plan has encountered some difficulties” in three recent test failures, Liang tells China Daily, an English-language state-mouthpiece newspaper aimed at foreign readers. “When an object is bigger, its technical risks and functional defects are also magnified,” he says. The specific challenge is in machining. CALT is pushing its suppliers, he says, thereby revealing that the machining work is not done in-house.
In 2007, the Long March 5 was due to make its first flight in 2013. A year ago, the target had slipped to 2014. China Daily now says the first flight will “probably” occur in 2015. Neither current Chinese space launchers nor others that are being developed in parallel with Long March 5 can handle the 20-ton modules of China's space station or the largest spacecraft that will be built at a new plant at Tianjin (AW&ST Jan. 28, p. 27). At least in its early versions, the Long March 7 medium-heavy sibling of Long March 5 will not be able to loft satellites based on a new spacecraft bus, the DFH-5.