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China's Shijian-10, the second of four scientific space missions, carries a collection of microgravity experiments.

China's Shijian-10, the second of four scientific space missions, carries a collection of microgravity experiments.


China takes microgravity work to new heights

China's space science ambitions mark a new milestone today with the launch of a microgravity research satellite set for 2 a.m. Wednesday morning Beijing time. The Shijian-10 (SJ-10) spacecraft carries 20 experiments covering fluid physics, materials science, and the effects of radiation and microgravity on various biological systems.

The mission deepens China's international cooperation in space, carrying an experiment jointly developed with the European Space Agency (ESA). "We have been sharing scientific data and sharing results" with China, says Antonio Verga, an ESA microgravity researcher in Noordwijk, the Netherlands. In particular, ESA scientists worked with Chinese colleagues on the Geospace Double Star Exploration Program, though the mission's two satellites were developed and launched by China's National Space Science Center (NSSC). SJ-10 "is the first cooperative mission in which ESA is actually flying a piece of hardware on a Chinese mission," Verga says.

The SJ-10 spacecraft will be launched on a Long March 2D rocket from the Jiuquan Satellite Launch Center in northwestern Gansu province. After 12 days in orbit, a re-entry capsule will return most samples to Earth, landing in Inner Mongolia. The short time frame is typical for space microgravity missions, Verga says. Experiments on the orbiter will continue for three more days, running on batteries for power.

Microgravity researchers welcome China's growing interest. "They are improving a lot the level of their research," says Ricard González-Cinca, a physicist at the Polytechnic University of Catalonia in Barcelona, Spain, who is not involved in the mission.

The scientific payload is a grab bag of experiments. It’s “a very interesting mission,” says NSSC Director General Wu Ji in Beijing. Two combustion experiments will test how materials used in spacecraft burn in space to find ways of making safer capsules for human spaceflight, for example, while another experiment will study crystal growth in semiconductor materials and alloys. Three experiments will investigate how radiation affects genetics, also partly to make future human spaceflight safer. Early mouse embryos will be watched to see whether they develop normally, for clues to whether humans or other mammals could reproduce in space.

One experiment seeks to shed light on a very earthly phenomenon. The Soret Coefficient in Crude Oil experiment—a collaboration among between ESA, NSSC, France’s Total oil company, and PetroChina—will investigate the behavior of crude oil under high pressure to understand the characteristics of deep oil reservoirs. Their apparatus has six cylinders, each containing a milliliter of crude oil subjected to more than 400 times atmospheric pressure. One end of the tubes will be heated, the other end cooled. Verga says that under the very high pressures found about 4 kilometers underground, lighter oil components diffuse toward the warmer, or lower, levels of a reservoir, whereas heavier components rise despite gravity. The Soret Coefficient measures this effect. This happens over geologic timescales on Earth, but Verga says they hope to replicate the process in a few weeks in the microgravity of space. A better understanding of the phenomenon "is important for oil companies doing exploration," he says.

SJ-10 is one of four missions all initiated at the same time under a 2011 Strategic Priority Program on Space Science. The Dark Matter Particle Explorer was the first to be launched, last December. This summer, NSSC will put its Quantum Experiments at Space Scale satellite in orbit to test the concept of quantum entanglement. The Hard X-ray Modulation Telescope, to study high-energy physics processes in space, will follow probably before the end of the year.

*Correction, 18 April, 7:13 a.m.: A previous version of this story gave an incorrect underground depth for the high pressures being replicated by the Soret Coefficient in Crude Oil experiment.