For its first week in space, China's lunar orbiter circled Earth in elongated orbits with ever-increasing high points. Like a child in a swing pumping both legs to fly higher, the Chang'e spacecraft repeatedly fired its small thrusters to test its steering before the big jump all the way to the moon.
On Wednesday, the jump began. Between now and Nov. 5, any aiming or propulsion errors could be catastrophic. The true test of China's aspirations beyond Earth orbit is well under way.
Chang'e is pioneering new routes along the "sea lanes of space" that may be followed in later years by larger and larger space vehicles. China has been developing a variety of new vehicles to make the journey possible, including rockets and spaceships. But one of the most important vehicles in Beijing's plans will never travel in space: It's an oceangoing barge.
Using a barge to transport space may not sound like a big deal, but the system will play a critical role in China's growing space program.
Chinese space experts publicly mentioned the barge concept for the first time on Wednesday morning, with the official announcement of government approval for the next-generation launch vehicle.
They have not shown any photographs or artist's depictions of the system. Because the oceangoing vessel will need to travel through waters patrolled by Taiwan, perhaps there are good diplomatic reasons to avoid drawing attention to it. Nevertheless, Wednesday's confirmation of the plan for oceangoing missiles comes as no surprise to veteran space watchers — since everything else China had been doing, and talking about, strongly implied that they would need to start building this system, and soon.
An island spaceport for a new rocket
Last month, China officially approved plans to build a fourth spaceport on the southern island of Hainan. Commentators at that time pointed out that a southern launch site could provide an additional eastward "push" to enhance the payload performance of a rocket launched into orbit. The island site would also provide a variety of launch paths that would not overfly populated areas — a particular concern for China after a rocket failure in 1995 killed hundreds of people in a village near a launch site (the same rocket used for this month's moonshot, it turns out).
All these comments overlooked the most important advantage of the island launch site — its "reachability" from other places in China. Big new rockets, the kind that will be critical to any future expansion of Chinese space launch capabilities, can be transported from their factories to the new site without having to pass through tight railway tunnels. They can be made as long and wide as desired, then transported to the pad by barge.
Until now, all the rockets in China's Long March series have been assembled from components with basically the same dimensions — up to 50 feet (15 meters) long but less than 8 feet (2.4 meters) in diameter. More powerful units are created by strapping add-on segments to the sides of core vehicles. It is the same basic shape as is used by Chinese military missiles, as well.
This maximum diameter means that all of these vehicles can be transported piece by piece to all three existing inland launch sites by railroad. And they will continue to be shipped this way indefinitely, in support of launches of Shenzhou human spacecraft, of science and applications missions, of commercial communications satellites, and even of small moon probes like Chang’e 1.
But China's planned Long March 5 rocket is different. Designed to triple China’s current launch performance, and to match the power of the European Ariane 5 or Russia's Proton, the booster will also use a totally new combination of rocket propellants. And its tank structure is being completely redesigned — making it much wider than any previous space booster component built in China. Announced designs specify a diameter of almost 18 feet (5.4 meters) — clearly too large for long-distance surface transportation.
The long-awaited Long March 5 is supposed to make its first spaceflight about 2010. An artist’s conception of the rocket, in a sales brochure distributed two years ago, showed the rocket blasting off from a launch pad that had palm trees in the background — not the flora common at the current desert and mountain launch sites China now operates.
Rise of the space navy
Enter the oceangoing barge method. In their exhaustive study of overseas space programs for lessons they could use themselves, Chinese space experts no doubt noticed that, in the 1960s, barge transport was the key to moving Saturn rocket components from coastal factories to coastal launch sites in the United States. These facilities were located and constructed from the start to enable this method.
Russia, on the other hand, used a land-locked spaceport in the Kazakh desert. Rocket segments for small and medium-class rockets could be (and still are) transported by rail, but when Moscow built its superboosters, first for the Cold War moon race and later for its Buran shuttle, it had to build at the launch site an array of factories and an entire city to support the workers and their families, at immense cost.
Air transport, the key to moving NASA’s space shuttles from their factory and, later, from contingency landing fields back to Kennedy Space Center in Florida, was never a serious option for the Russians. Soviet engineers were barely able to move their hollow Buran fuselages and fuel tanks atop a converted bomber, but they didn’t own anything like the Boeing 747 transports for carrying a fully assembled shuttle — at least not until the very end of the program’s development, when it was too late.
China owns some 747s, but the blow to national pride of using a foreign-built plane to carry their country’s most advanced space hardware would probably be too great. Besides, there isn’t a 747-capable airfield close enough to the planned Hainan Island launch site.
So the connections between the new Long March 5, the new Hainan Island space base and the new requirement for transporting much wider rocket stages than ever before make perfect sense. The booster, Chinese space officials have stated, will be commercially justified as a carrier for Chinese-built communications satellites that already are being offered on the world market. It will carry the planned Chinese small Mir-class space station, and the planned robot moon rovers and sampler missions planned for the middle of the next decade. It will also open the path for Chinese astronaut missions to the vicinity of the moon or even other more interesting locations far from Earth.
The barge system, meanwhile, will inaugurate a space booster infrastructure design that will allow even larger rockets to reliably be moved from factory to launch pad. If and when China decides to build a Long March 6 — the equivalent of the Saturn 5 moon rocket that would be needed to land its astronauts on the lunar surface in a time frame competitive with U.S. plans — the first thousand miles of that vehicle’s travel will be by humble barge.
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