The Chinese space program raised its eyebrows again – this time because of its proposal to investigate the construction of a large spaceship at least one kilometer in length.

To put this in perspective, the International Space Station (ISS) is only 109 meters wide, but cost $ 150 billion (£ 110 billion) and took thirty missions over a decade to build. China’s proposal is for a spacecraft ten times the size of the ISS. It may sound crazy, but don’t make the mistake of dismissing it now.

"It’s about ambition, long-term thinking and determination. Such long-term thinking doesn’t go well with short-term Western thinking, which may mistakenly dismiss it as propaganda, "says space writer Brian Harvey, author of China in Space: The Great Leap Forward.

There is no doubt that China has made serious advances in space exploration recently. It has sent moon rock samples back to Earth for analysis, making it the third country to do so after the US and Russia; it landed a rover on Mars, an achievement that only the US had previously achieved; and it made the world’s first landing on the far side of the moon. In addition, China is now building the Tiangong space station, which was inhabited for 90 days this year and will eventually compete with the ISS.

Looking ahead, Harvey points to a 2009 Chinese report called Roadmap 2050, which is the blueprint for how China aims to become the world’s leading space nation by mid-century. "The horizon of Chinese space travel is not years or decades, but half centuries," he says.

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In other words, this latest announcement marks the beginning of China’s thinking about how to build such a spaceship in the future rather than a statement that it intends to begin building it.

The idea was featured in a broader call for research from the National Science Foundation of China – a funding agency managed by the country’s Ministry of Science and Technology. It is offering 15 million yuan (1.7 million pounds) for a five-year feasibility study of new lightweight designs and materials and construction techniques in space.

But why would China want a spaceship ten times larger than anything that has ever been built? The answer could be artificial gravity. An artificial gravity space station could help astronauts fight off some of the most damaging effects of weightlessness like muscle wasting and bone density loss.

On long-term space flights to Mars or beyond, artificial gravity could make a dramatic difference in keeping the crew healthy.

Stanley Kubrick’s 2001: A Space Odyssey showed a rotating space station © Alarmy

"Artificial gravity has been that ‘science fiction’ holy grail thing for human spaceflight for a century, and the main way to do it is through a large, spinning structure," said Zachary Manchester, assistant professor at the Robotics Institute Carnegie Mellon University, Pennsylvania.

Within a spinning structure, centrifugal force moves things outward. When the structures spin at the correct speed, it can create a force that mimics the effects of gravity.

The problem with this is that humans are very susceptible to rotational speeds. If you spin faster than a few revolutions per minute, the average person will suffer from motion sickness.

However, experiments have shown that these effects practically disappear at speeds of one to two revolutions per minute. So how big would a spaceship have to be to create Earth’s gravity by spinning at a leisurely 1-2 rpm?

"It turned out that you needed a structure about a kilometer in diameter," says Manchester, who received a grant from NASA in February of this year so that he and his colleagues could study a construction scenario for a one-kilometer space probe .

While China, after launching numerous components into space, appears to be considering how to build something huge in orbit, Manchester is investigating whether it would be possible to build a full structure that sits in the nose cone of a single large rocket, a SpaceX Falcon , would fold hard for example. It would then expand tremendously once it was deployed in space.

The key to this idea lies in the use of so-called mechanical metamaterials. These use scissor-like joints to fold down to a fraction of their unfolded size. The best known example of such a mechanical metamaterial is the Hoberman sphere. This children’s toy resembles a small spiky ball when at rest, but can expand into a large ball many times its original diameter.

The Hoberman Sphere, a children’s toy, is an example of a metamaterial that could help engineers design gigantic space stations © Getty Images

"It turned out that you can put together some really interesting mechanisms that can get very, very high rates of expansion," says Manchester.

The structures he studies can expand to hundreds of times their original size. Science ‘fictiony’ indeed! Only time will tell if either design will work, but it is now very clear that the world’s greatest space powers are looking forward to developing spacecraft that are much larger than any we’ve made to date.