Another delay besets the heavy launcher on which China's space program is betting
Somewhere in China, technicians are struggling with their machine tools, trying to make huge but perfectly shaped metal structuresâ€”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 availableâ€”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.
â€śOur plan has encountered some difficultiesâ€ť in three recent test failures, Liang tells China Daily, an English-language state-mouthpiece newspaper aimed at foreign readers. â€śWhen an object is bigger, its technical risks and functional defects are also magnified,â€ť 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 â€śprobablyâ€ť 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.
China's main spacecraft builder, the China Academy of Space Technology (CAST), may be hedging its bets on Long March 5 by developing a bigger version of its DFH-4 bus that, with a designed launch mass of 5.5 tons, is just small enough for launch to geosynchronous orbit by a current rocket, Long March 3B (see table). CAST is developing that larger bus, DFH-4E, along with a smaller derivative of the baseline DFH-4 called DFH-4S. The program is ahead of DFH-5, which state space marketing company China Great Wall Industry Corp. says â€śis still in its initial development phase.â€ť In late 2010, DFH-5 was due to go into service in 2016 or 2017, but no firm target is given now. The DFH-5 bus will â€śmeet the demand for new-generation large [geostationary] communications satellites and Earth-observation satellites.â€ť
Long March 11 will launch much smaller satellites. With solid fuel, it will be ready for firing at short notice, offering the ability to send a reconnaissance spacecraft aloft almost as soon as a tactical need for one arisesâ€”for example, to sweep a patch of ocean for enemy ships. Liang describes Long March 11 as having value in civil missions such as post-disaster reconnaissance, but Chinese space officials routinely refer to non-military applications of equipment that have obvious military uses. One official last year said that the payload of a then-planned but unnamed solid launcher might be 1 ton.
Long March 7, the second member of the new liquid-propellant Chinese launcher family, has also been delayed, though perhaps not much. A year ago, it was due to fly late in 2013; now the target is 2014. It and a smaller relative, Long March 6, will use body and booster diameters of 3.35 and 2.5 meters, which Chinese industry is already adept at building for rockets dating back to the 1960s that use toxic hydrazine fuel.
Liang adds that Long March 7 may become China's manned launcher. As such, it would replace Long March 2F, a member of the hydrazine-fueled family that should ultimately be superseded by the group of rockets now under development. The authorities will surely not rush to anoint Long March 7 as their manned launcher, however. Apart from redundant and more robust systems, it will presumably need a long record of unmanned launches before it is trusted to carry people.
Long March 7 and Long March 6 will use kerosene fuel. Liang says the old hydrazine-burning Long Marches will serve alongside the new generation for 10-20 years. Long March 6 appears to be intended for launching reconnaissance satellites on polar orbits. A year ago, its program timing was close to that of Long March 7; the latest report makes no mention of it.
The state space industry is scheduled during the current five-year planning period, 2011-15, to request government approval to develop a launcher for manned Moon missions, China Daily says in the same report. Since that planning period is already well underway, the industry must hope to launch full-scale development no earlier than 2016. The Moon rocket, with an 8-meter diameter, would loft 100 tons to low Earth orbit, making it smaller than the U.S. Saturn V used in the 1960s and 1970s. The Tianjin space manufacturing base has been sized for diameters up to 10 meters.
The U.S. Apollo program experience suggests that a 100-ton throw weight to low orbit would not be enough to launch a lunar mission in a single shot, so Chinese space program managers appear to be considering at least two launches for each mission: one for the major part of their lunar spacecraft and one for the manned capsule. The Long March 7 is evidently a candidate for the separate launch.
|Total mass (kg/lb.)||5,100/11,200||3,800/8,400||5,500/12,000||6,500â€“7,000/14,300-15,400|
|Payload mass (kg/lb.)||600/1,300||450/990||1,000/2,200||1,200-1,500/2,600-3,300|
|Total power (watts)||10,000||7,000||16,000||15,000â€“20,000|
|Power supplied to payload (watts)||8,000||4,000||11,000||Not available|
|Sources: CAST and China Great War Industry Corp.|