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In the fifteen years since the International Space Station has been in operation, this multi-nation venture has steadily advanced our understanding of science, from astronomy, to human physiology, to materials science. It represents a global effort in scientific research and includes five participating space agencies, from the U.S., Russia, Japan, Europe and Canada. Noticeably absent is China. The Chinese would like to see that change.

"As an astronaut, I have a strong desire to fly with astronauts from other countries," said Nie Haisheng, a Chinese astronaut and commander of the Shenzhou 10 mission in an interview with CNN. "I also look forward to going to the International Space Station.

But U.S. lawmakers see things differently. In fact, they passed an act barring NASA from any cooperative space ventures with China back in 2011, out of fears for national security. And they don't seem likely to change their mind anytime soon.

"Every time it gets mentioned at all anywhere near Congress, it gets shut down immediately," space analyst Miles O'Brien told CNN. "There is tremendous skepticism there about China. It is viewed as a foe, it is viewed as a government that seeks to take our intellectual property -- our national secrets and treasure."

China has tried to assuage those fears, advocating for a change in policy through political representatives and the Chinese astronauts themselves.

"The Chinese government has always advocated the peaceful use of outer space, it opposes space weaponization and an arms race in outer space. This position will not be changed," Wang Jin, a spokesman for the Ministry of Defense, told CNN.

Commander Nie Haisheng put it plainly.

"...Space is a family affair, many countries are developing their space programs and China, as a big country, should make our own contributions in this field."

And they've done just that. China launched its own manned space program in 1992 and has made steady progress ever since. They put their first man in space in 2003, completed their first spacewalk five years later, and in 2013, Commander Nie and his crew twice docked with the Tiangong-1 space lab, China's scaled-down version of the ISS, completing the country's longest space mission to date.

Most recently, China completed an unmanned mission to orbit the moon. In October, a small orbiter travelled 840,000 kilometers during its eight-day mission around the moon, capturing detailed images of Earth and its satellite.

So China is not sitting by the sidelines, waiting for an invitation to space. Their agency will move forward, as will ours. And perhaps sometime in the future, we can all work together.