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China Daily: Tiangong II pushes new research boundaries
Update time: 10-30-2018
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Space lab fulfills all planned missions within two years 

Early on April 2, Tiangong I fell back to earth after first entering service in September 2011.

Its exterior broke up and incinerated in the morning sky as scientists worldwide witnessed the final stages of China's first space laboratory before its remains plunged into the southern Pacific Ocean.

Now, all eyes are on its successor, Tiangong II, China's sole space lab orbiting Earth. It recently passed its second anniversary in orbit since being sent into space from the Jiuquan Satellite Launch Center, Gansu province, on Sept 15, 2016.

Lin Xiqiang, deputy director of the China Manned Space Engineering Office, said Tiangong II would safely end its orbit under manual control after July.

"Tiangong II has fulfilled all its planned missions within its designed two-year life span," Lin said.

It will now focus on conducting additional experiments and testing new space applications that can benefit society, he added.

These benefits include providing valuable geological data for research and disaster relief, as well as enhancing local economies in the Ningxia Hui autonomous region and Yunnan province, home to many companies involved in the country's space sector, he said.

The space laboratory serves as a symbol of national pride and scientific education, where people can cultivate their love for space technology and exploration, Lin added.

A simulator displays the successful docking of Tiangong II and the Shenzhou XI manned spacecraft

on Oct 19, 2016. [Photo by Wang Juan/For China Daily]

Tiangong II carries a payload of 600 kilograms in total. It is conducting research ranging from particle physics to materials science and remote-sensing technologies, according to the engineering office.

In late 2016, Tiangong II docked with Shenzhou XI and hosted two astronauts, Jing Haipeng and Chen Dong, for 33 days in China's longest human space flight mission to date.

Last year, it was visited by the Tianzhou I cargo spacecraft to test and verify refueling capabilities in microgravity, making China the third country, after Russia and the United States, to master the technique. Such capability is crucial to maintaining a space station.

The 10.4-meter-long, 8.6 metric-ton Tiangong II also tests advanced life support systems for astronauts who will man China's upcoming space station, whose core module will be launched around 2020, with the entire station set to be completed about two years later, CMSEO said.

Lin said the country's manned space program is also expanding its global cooperation and exchanges to jointly promote the peaceful use of space technologies, adding China has already cooperated with Russia, France, Germany and Italy.

As of Oct 3, China had received 36 international science cooperation project proposals from 25 countries and regions for its space station, Lin said. The projects cover a range of topics including astrophysics, medicine, life science and bioengineering.

"China will continue to uphold the principles of peaceful, fair and mutually beneficial use of space technologies, and expand exchanges and cooperation with other countries," Lin said.

On Oct 12, Chen Jie, director of general planning at CMSEO, said China has established a 37-member committee to set various technical standards for its space station. These standards are expected to be completed by 2020.

They will cover research and development of manned space technology, its applications and related services, said Chen, adding that the new standards represent a breakthrough in China contributing its knowledge to "space-related international norms".

The International Space Station, the only one in operation, will be retired in 2024, although efforts are being made to possibly extend this to 2028 or beyond. But this risks pushing the station's hardware close to its certified operational limits, according to NASA.

It also means China could become the only country with a functioning space station capable of critical in-orbit research after the international station is retired.

In the meantime, Tiangong II's payloads are operating in good conditions and carrying out experiments as planned, said Guo Lili, director of payload operation at the Technology and Engineering Center for Space Utilization of the Chinese Academy of Sciences, or CAS.

"Tiangong II's new chapter of scientific research and discovery has just begun," she said.

Fruitful experiments

Tiangong II orbits the Earth once every 90 minutes, CMSEO said. The space lab, whose name translates as "Heavenly Palace", houses the world's first and most accurate timepiece, the Cold Atomic Clock in Space.

The clock uses atomic physics, lasers and the microgravity in space to keep time. It will take 300 billion years before it loses a single second, according to CAS.

Such ultraprecise timepieces are generally used for calibrating extremely sensitive electronics, such as global positioning systems, or conducting experiments in physics that depend on extreme accuracy.

The clock is just one of many items of advanced scientific equipment launched with Tiangong II. Another notable item is the academy's botanic growth chamber that allowed the astronauts to grow rice and plants to maturity in space for the first time.

Zheng Huiqiong, a researcher from the academy's Institute of Plant Physiology and Ecology, said, "Growing plants is a crucial capability for building a sustainable ecosystem to support humanity's long-term residence in space."

China has conducted similar experiments in the past but could only grow plants to an early stage due to limited space and technical difficulties. However, thanks to a newly developed incubator box, thale cress and rice can now be grown to their full potential, Zheng said.

Tiangong II is also equipped with POLAR, a gamma ray burst detector developed by an international collaboration including Chinese, Swiss and Polish scientific institutes. It is the world's first detector dedicated to measuring the polarizing effect of these bursts, which are flashes of gamma rays associated with extremely energetic explosions observed in distant galaxies. Bursts can last from 10 milliseconds to several hours.

Lyu Congmin, deputy chief engineer of the space application system for China's manned space program, said POLAR has successfully detected 55 gamma ray bursts.

Tiangong II has also contributed to the field of quantum communications, taken to new heights when the country launched Micius, the world's first quantum communications satellite, in August 2016.

Quantum information science is an emerging field that uses the strange properties of quantum mechanics to create new applications, such as ultrafast quantum supercomputers or hack-proof quantum communications.

Lyu said Tiangong II has conducted experiments on quantum key distribution-the exchange of cryptographic keys between two parties-by sending "entangled photos" (particles of light), from space to Earth. A cryptographic key is a string of bits used by a cryptographic algorithm to transform plain text into cipher text or vice versa.

This type of communication is inherently secure, because any attempt to eavesdrop will affect the entanglement and immediately be detected, Lyu said. Such technology will have widespread applications in fields where security is paramount, such as government, defense and finance.

Tiangong II's quantum experiments have consolidated China's leading global position in space quantum science and technology, Lyu said.

Benefiting society

During a livestream session on Nov 20, 2016, Jing Haipeng and Chen Dong, the astronauts aboard Tiangong II, conducted an unusual experiment in orbit-drinking the first cup of tea in microgravity.

They "poured" water into the bottom of a special cup and watched it flow upward into the chamber. The water then mixed with a pu'er tea paste, and the mixture was automatically heated without using a flame.

Jing then drank the tea while floating upside down. "Delicious" he said after finishing the drink while drifting leisurely in the cabin.

Jiang Xiaowei, vice-president of the Association for Space Biotechnology Development in Yunnan, the creator of the "space tea", said, "For decades, astronauts could only drink liquid by squeezing pre-made bags of fluid. Drinking tea in space, like on Earth, was unthinkable."

To improve astronauts' drinking experience in space, CMSEO created the special cup used in the demonstration. However, bioengineering the tea so that it could be drunk in space was very tricky, Jiang said.

The tea must dissolve fully without boiling water being used, as this can be dangerous in space, she said. The paste also cannot leave any residue, because this could create unnecessary trash in the cabin.

Yunnan is home to many of the country's tea producers, Jiang said. "The space tea can not only improve living standards and health for astronauts, its manufacturing techniques can also help reform China's tea industry and make it more appealing and competitive in the global market."

Space tea is one of many technologies that can benefit people on Earth. According to NASA, many of the technologies it has developed have filtered down to mass use, including dehydrated foods, memory foam, scratch-resistant lenses, baby formulas and body-imaging techniques in medicine.

Li Shenchong, a botanist from the Academy of Agricultural Sciences in Yunnan, said China is hoping to build a "flying greenhouse" in space to produce new varieties of plants and crops that can benefit future astronauts and local economies.

"The microgravity and radiation in space can mutate plants' genes, possibly leading to new varieties with more positive traits, such as high-yielding and insect-resistant types," he said.

Since 2016, China has sent 94 different types of garden flowers, medicinal plants and fungi into orbit for selective breeding, Li said.

"New plants with more positive traits will have higher economic values, and this will help improve earnings for farmers and make China a greener and more beautiful country."

Apart from commercial products, Tiangong II has provided geological and climate data for more than 70 government agencies and research institutes in China, Lyu said.

The data are widely used and invaluable for weather forecasting, environmental protection, disaster relief and use of land and marine resources, he added.

(Source: By Zhang Zhihao | China Daily | Updated: 2018-10-29 08:03)

@ Shanghai Institute of Optics and Fine Mechanics Tel:02169918000 Shanghai ICP NO.0501538