PARIS — French-China cooperation in space-based astronomy and biomedical research has been slowed by the U.S. government’s continued redefining of what is and what is not allowed for export to China, an official with the French space agency, CNES, said Sept. 18.

France has several bilateral missions planned with the China National Space Administration. One is called Cardiospace, which will be launched on China’s Tiangong-2 space station module in 2016 and used to study Chinese taikonauts’ circulation. Two Cardiospace units were delivered to the Astronaut Center of China in March and June to be integrated into the 20,000-kilogram Tiangong-2.

A more recent agreement concerns an astronomy satellite called SVOM, or Space-based multi-band astronomical Variable Objects Monitor, that is scheduled for launch in 2021 aboard a Chinese Long March rocket. CNES is providing two of the four SVOM instruments, which are designed to detect and analyze gamma-ray bursts, and to alert ground-based telescopes to their occurrence.

Biomedical research of the kind being conducted with the Cardiospace experiment is a large business between China and the West, including the United States. But the “space” element sets it apart in U.S. technology export regulations, known as the International Traffic in Arms Regulations.

ITAR regulations generally are being rewritten to restrict fewer space-related items and correct what even some of the original backers of a 1999 export crackdown agree has been an unintended consequence in sharply reducing certain U.S. exports.

U.S. Rep. C.A. Dutch Ruppersberger (D-Md.) on Sept. 17 said ITAR is why U.S. companies’ share of global space exports has fallen from 72 percent to 27 percent in the 15 years since ITAR was expanded to cover virtually all space components. “And it’s still slipping,” he said during an address to the U.S. Commercial Space Transportation Advisory Committee.

Many space industry officials would disagree that the drop in U.S. space exports should be laid entirely at ITAR’s doorstep. But space component manufacturers have complained for years that once-regular customers in Europe, Asia and elsewhere have moved to other suppliers because of ITAR.

ITAR’s ongoing reforms do not change the strict U.S. ban on space exports to China, which is why CNES had to spend so much time stripping the Cardiospace and SVOM missions of every U.S. component for which there was a reasonable replacement.

Fabienne Casoli, CNES deputy director for science, said Sept. 18 that the problem was a kind of shell game in which a component classed as OK for export today is reclassed tomorrow as being on the prohibited list.

Similarly, she said, CNES officials designing the SVOM instruments have been obliged to make educated guesses of future ITAR iterations that may occur before the mission is launched in 2021.

“The American export restraints caused us to take more time than we would have needed otherwise to determine the two sides’ share of responsibility,” Casoli said of negotiations with China over SVOM. “The components we were going to use in the beginning were not the ITAR list, but were put on the list later. The other problem we have is components that are not currently on the ITAR list, but that might be added later.”

Casoli said CNES has reduced to the bare minimum the amount of U.S. content in both SVOM and Cardiospace, and that those that remain have been closely analyzed to determine the likelihood of a future ITAR classification.

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Peter B. de Selding was the Paris bureau chief for SpaceNews.