With the launch of China's first microgravity satellite, SJ-10, early on Wednesday, scientists look forward to the results of experiments that could shed new light on a range of questions, from biology to the physical properties of substances, in a weightless environment.

The recoverable satellite blasted off from the Jiuquan Satellite Launch Center in Gansu province at 1:38 am, carried by a Long March 2-D rocket. It will stay in orbit for several days before its return capsule heads back to Earth. The orbital module will continue to conduct experiments for a few more days.

"Microgravity - the environment created during weightlessness - is an extreme condition that changes every physical phenomenon we are familiar with, which is why microgravity research has been a science hot spot internationally," said Hu Wenrui, the chief scientist on the SJ-10 project, who is a prominent physicist and a member of the Chinese Academy of Sciences.

For example, liquids cannot be contained without the use of containers on Earth. But in a microgravity environment, liquids can float without a container, which makes it possible to determine the material's characteristics, to understand its chemical reactions and to develop new materials with new functions.

Microgravity experiments are normally carried out in various space facilities, such as space stations, shuttles, research rockets or orbiting satellites. The SJ-10 is designed to return to Earth.

"The recoverable satellite is a useful and efficient tool for microgravity experiments, compared with space stations and research rockets," Hu said.

A research rocket, the cheapest option for such experiments, can create, at most, a 10-minute period of weightlessness for microgravity experiments. A typical satellite can stay a couple weeks in gravity-free space.

Space shuttles and orbiting space stations are much more costly, yet less flexible than satellites.

"For example, we are going to send some stem cells and early mouse embryos into space to study their development under microgravity conditions," said Kang Qi, a researcher at the Institute of Mechanics under the science academy and the chief designer of the experiment systems aboard SJ-10.

"To minimize the influence of gravity on them, we will assemble the samples only eight hours ahead of the launch, which would not be possible if we were using a manned spacecraft."

Designed in the shape of a bullet, SJ-10 will carry out 28 scientific inquiries. Eleven of the experiments will be recovered on Earth, while the others will remain in orbit.

The experiments include fundamental research in fluid physics, research to enhance fire safety for manned spaceflight, some biological experiments to improve human health and experiments related to coal combustion and materials processing.

"We are not repeating any experiments that have been carried out by other countries. Every single experiment is new," Hu, the chief scientist, said.

China's space science authority, known as the Commission on Science, Technology, and Industry for National Defense before its functions were merged into the Ministry of Industry and Information Technology and other ministries, has solicited experimental projects for the SJ-10 since 2005.

The 28 experiments selected were chosen from 218 candidates collected from research institutes and universities, both in and out of China.

The project was temporarily laid aside as a result of institutional adjustments in China's space science bodies. The science academy restarted it in 2011 as part of the larger Strategic Priority Program on Space Science, which plans to launch four satellites by the end of 2016.

The first in the program - focused on dark matter in the universe - was launched in December and has begun to collect data.

chengyingqi@chinadaily.com.cn

(China Daily 04/07/2016 page5)