China’s retrievable research spacecraft returns to Earth
China has successfully concluded its recoverable research mission, known as Shijian-10 (SJ-10), with the landing of the satellite’s re-entry capsule on Monday, April 18. The return vehicle touched down at about 4:30 a.m. EDT (8:30 GMT) at the planned landing site in Siziwang Banner in north China’s Inner Mongolia Autonomous Region.
The bullet-shaped spacecraft lifted off on April 5 atop a Long March 2D rocket at 1:38 p.m. EDT (17:38 GMT) from Launch Area 4 located at the Jiuquan Satellite Launch Center, located in northwest China’s Gansu Province. The mission returned to Earth after a 12-day stay in low-Earth orbit (137 × 300 miles; 220 × 482 km), inclined 63 degrees, during which 19 scientific experiments were carried out. According to Chinese media, the capsule was in good condition after landing.
The capsule separated from the mission’s orbital module about 15 minutes before its landing. It will be now delivered to the China Academy of Space Technology (CAST) and to the Chinese Academy of Sciences (CAS) for further analysis and assessment. The orbital module will remain in space to carry out further studies.
The car-sized Shijian-10 spacecraft has a launch mass of about 3.6 metric tons and is capable of carrying up to 1,320 lbs. (600 kg) of payload. It is based on the FSW satellite bus. The craft is powered by batteries instead of solar panels.
During its stay on orbit, the satellite conducted six experiments relating to fluid physics, three pertaining to combustion, and eight of materials science in the field of physical science, three experiments of radiation biology, three dealing with gravitational biology, and four of biotechnology in the field of life science.
One of the best-known experiments aboard Shijian-10 is the development of over 6,000 mouse embryos in space. This experiment, overseen by CAS, was designed to culture 2-cell or 4-cell stages of the embryos in a specialized instrument for about 96 hours.
On Sunday, the state-run Xinhua press agency confirmed that this study ended in success by developing early-stage mouse embryos in space. Chinese media report that 600 embryos were put under a high-resolution camera, which took pictures every four hours for four days and sent them back to Earth. The rest of the embryos loaded on the satellite were injected with fixatives at 72 hours after the launch for studies on the effects of space environment on embryonic development.
Another well-known experiment on board Shijian-10 is the Soret Coefficient in Crude Oil (SCCO) study. This research is a partnership between ESA, China’s National Space Science Centre, France’s Total oil company, and China’s PetroChina oil company. It consists of six sturdy cylinders, each containing just one milliliter of crude oil but compressed up to 500 times the normal pressure at sea level on Earth and heated on one end and cooled on the other to look at a diffusion process ongoing in Earth’s oil reservoirs. According to ESA, SCCO measured how hydrocarbon molecules redistribute when the temperature is not uniform.
The Space experiment of Evaporation and Fluid Interfacial Effects (EFILE), designed by the Chinese Academy of Sciences (CAS), studied the thermocapillary effect at the liquid-gas phase-change interface on evaporation in the space environment. By injection of a liquid droplet on the heating subtract, two kinds of sessile drop evaporation processes were investigated by the scientists.
Other physical experiments that were carried into space include ignition and burning of solid materials in microgravity and also a study on colloidal assembling.
The spacecraft also hosted experiments investigating molecular biology mechanism of space radiation mutagenesis and the roles of space radiation on genomic DNA and its genetic effects. One of the studies analyzed biological effects and the signal transduction of microgravity stimulation in plants.
The Shijian program started with the launch of the Shijian-1 satellite in 1971. The project includes various orbital flights for the demonstration of new technical systems for use on spacecraft as well as scientific missions. The first recoverable spacecraft in the series was Shijian-8, launched in 2006. The current Shijian-10 program was initiated in 2008 for the phases of space experiments selection, engineering preparations of space techniques, and scientific facilities designs. However, the program was stopped before the starting of the engineering phase and was restarted again in 2011.
According to Tang Bochang, general designer of the Shijian-10 mission, with improved carrying and supporting capabilities and microgravity environment, this spacecraft is likely to become China’s new generation of scientific experiment platform.
China’s first recoverable satellite was launched in 1975 and, so far, 24 recoverable satellites have been launched and recovered by the country.
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