Like London buses, three Chinese satellite platforms are coming at once
China may have had limited success so far in exporting commercial satellites, but it is investing heavily for the future. The country has two satellite buses in service and has taken export orders for only six, one a replacement for the in-orbit failure of another. Yet it is keenly aware of the foreign commercial market and has three more buses under development, with the aim of offering a product range with launch weights of up to 7 metric tons.
Noting the rising importance of commercial demand within the global space industry, Chinese launcher builder China Academy of Launch Technology (CALT) described the national commercial space strategy at the International Astronautical Congress (IAC) in Beijing in September. Apart from China's need to improve technology, CALT officials emphasized the importance of offering a wide range of services and products, optimizing and packaging them as necessary. Hugely staffed Chinese state organizations often have trouble coordinating activities such as these. Marketing is also a priority, say CALT officials Shan Wenjie, Wang Chafe, Dai Kun and Kang Sibei. That, too, is not a strong point of traditionally defense-oriented government enterprises.
Customers from advanced countries may be slow in emerging, but in other advanced industries, including aeronautics, China has first learned international business with sales to poorer countries, and it is doing the same in the commercial space market.
Much can be inferred about China's approach from its contract last decade for Nigeria's Nigcomsat-1, says Joan Johnson-Freese of the U.S. Naval War College. “China built and launched that satellite in 2007, beating out 21 other bidders for the project,” she notes. “The price was right and China has been willing, indeed eager, to establish itself as the country that will train space professionals from developing countries, including Nigeria, Pakistan and Bolivia.”
Johnson-Freese points out that “China can prove the reliability of its technology—establish a track record—through programs with developing countries, and then try to expand to other, developed countries looking for low-risk and competitively priced space technology.”
Part of China's plan is to offer a wider variety of satellite buses—standardized but incomplete spacecraft designed to support various payloads, such as communications gear. Officials from spacecraft specialist China Academy of Space Technology (CAST), a sibling of CALT in the China Aerospace Science and Technology Corp. (CASC) group, note that communications satellites increasingly need greater power supplies and heat-dissipation capacity, more space for transponders and greater launch mass. That means that China, while increasing the size of its satellite buses, has been chasing a moving target.
China's current offering is limited, with apparently only one bus, the DFH-4, in production for commercial clients. The DFH-4 has a launch mass of up to 5.32 tons, a maximum dry mass of 2.2 tons, including a payload of 700 kg (1,543 lb.), and power of 10.5 kw, of which the payload receives up to 8 kw. CAST says 10 satellites built on that model bus have been launched, the last eight successfully. One, Venezuela's Venesat-1, has served for five years.
But three new satellite buses are being developed, all derived from the DFH-4 to varying degrees. The first, the DFH-4S (for “small” and “smart”), is aimed not at meeting demand for larger buses but at extending the range to a lower size. CAST says it began developing the DFH-4S in 2006, 10 years after the DFH-4 effort started and just as that latter bus was first launched.
The DFH-4S also introduces advances in avionics and batteries, which use lithium-ion technology, and it has a plasma propulsion system (PPS), says CAST. The maximum launch mass of a satellite built on the DFH-4S bus will be 4.6 tons and dry mass 1.59 metric tons, of which up to 450 kg will be the payload. Power will be 7.8 kw, of which up to 4 kw can be supplied to the payload.
The manufacturer says it has signed a sale for the DFH-4S but does not identify the customer, which is presumably another state agency. A forerunner of the new bus, the Chinese Experimental Satellite, “is also scheduled to be launched, through which CAST will facilitate in-orbit validation of PPS and other technology of communication satellites,” it says.
In 2010, CAST began developing another member of the family, the DFH-4E (for “enhanced”), using some new technology and some from the DFH-4S. “Compared with the DFH-4 platform, the DFH-4E has bigger communications-module dimensions, higher power capacity and heat-dissipation capability, and provides better adaptability for more complex payload design,” CAST officials Liu Likun, Wang Yihong, Shi Ming and Wei Qiang said at the IAC.
The DFH-4E will have triple-junction gallium-arsenide solar cells generating 65 kw per kilogram. By using lithium-ion instead of nickel-hydrogen technology for batteries, the designers have saved 80 kg, says CAST, which adds that it is also looking at further developments in solar cells and batteries. Like the DFH-4S, the DFH-4E will use a plasma (electrical) propulsion system. The attitude determination and control system is being improved to keep the DFH-4E aligned to within 0.04 deg. for roll and pitch and 0.1 deg. for yaw; the equivalent figures for the DFH-4 and DFH-4S are 0.06 deg. and 0.2 deg.
A further advance for the DFH-4E is the introduction of an overlapping arrangement for fitting more antennas on to the spacecraft.
The objective of the DFH-4E program is to create a competitive offering that benefits from DFH-4 and DFH-4S, says CAST. “DFH-4E system-level verification includes a mechanical model to demonstrate [the] longer cylinder and communications module (CM), multi-floor CM, enlarged propellant tank [and] overlap antenna. A thermal module is used to verify the thermal design of the multi-floor communication [module].” The electrical design, including interfaces between subsystems, has followed that of the DFH-4S. The DFH-4E is expected to pass all qualification requirements and “offer a mature platform to customers with little risk.”
The third new bus is the DFH-5, with a maximum mass of 7 tons matched to the throw-weight of the forthcoming Long March 5 heavy launcher. Total spacecraft power, up to 20 kw, will be almost double that of DFH-4. Three years ago, DFH-5 was due to go into service in 2016-17. CAST and China Great Wall Industry Corp. (CGWIC) have not updated that, but a year or two of development slippage may not matter, because the Long March 5 is running late. In March, state media said the launcher will “probably” fly in 2015.
The status of the old DFH-3 bus, first launched 19 years ago, is unclear. With a maximum launch mass of 2.32 tons, payload power of 1 kw and design life of “at least eight years,” it has little competitiveness in the international commercial market. CGWIC seems no longer to be promoting it for export, but it is still used for Chinese government missions, such as the Chang'e lunar exploration program. An upgraded design, the DFH-3B, with the same 15-year design life as the later Chinese buses, is in production, and a version with lithium-ion propulsion for north-south station keeping is due to be launched in 2015.
Chinese private enterprise will soon move into the international space industry, officials of CALT said at the IAC. “In China, there is no real private enterprise to take part in international commercial aerospace activities, but state-owned space enterprises have taken advantage of private enterprise's advanced technologies,” they said, giving no examples. “With the development of market economy reform and the progress of the scientific research power of private enterprises, we can believe that China's private enterprise will emerge on the international commercial aerospace stage in the near future.”
Still, the appearance of private China launch services in the next decade would be surprising. Across the Chinese economy, it is a challenge for private businesses to compete with protected state enterprises. And although the national leadership is seeking to liberalize the economy, resistance to competition from CASC and China Aerospace Science & Industry Corp., another state space manufacturer, will surely be powerful.