China's Space Program News Thread

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The Jiuquan Satellite Launch Center is ready for its mission of sending Shenzhou-11 spaceship and Tiangong-2 space lab into space. Two carrier rockets are already ready at the center for blast-off, first to send into space the Tiangong-2 space lab and then to ferry two astronauts with Shenzhou-11 to dock with the lab for a joint space travel for up to 30 days.

Jiuquan is so far China's one and only launch site for manned space flights. And the center has just gone through a three-year thorough revamp which has transformed it into a better facility for launching manned spacecrafts.

"The revolving platform will envelope the spacecraft while flights of stairs reach the work station to facilitate our engineers. Besides the huge temperature differences between winter and summer, there are a lot of sand grains brought in through strong winds which cause difficulties for testing and launching operations. So we need to clean up and maintain the work station in good order very often," explains Li Bing, chief engineer with the testing and launching station at the Jiuquan Satellite Launch Center.

According to Li, up to 22 full-length technological renovations have been done during the past three years in order to forge a more favorable environment for launching manned spaceships in future. Li and his staff are confident when facing the new challenge that they have two instead of one carrier rockets complete with manned spacecrafts. His team now has to serve both the Shenzhou-11 and Tiangong-2 and their carrier rockets at the same time.

"This is the first time for us to have two manned spacecraft and two carrier rockets at the launching site at the same time. We have to carry out the maintenance work simultaneously. Up till now our work has been carried out smoothly to ensure the successful accomplishment of the two missions," says Li Bing.

 

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China is ready to conduct the experiments on quantum communications after the country launches the world's first quantum satellite, according to researchers at the Shanghai Control Center for Quantum Secure Communications.

The control center has been running test operations for the coming experiments in coordination with five other sub-control centers in Beijing, Xinjiang Uygur Autonomous Region, Qinghai Province, Yunnan Province and Tibet Autonomous Region.

"The sub-control centers are like the limbs of a person, and the main control center is like the brain. So the brain sends directions to the limbs, and the limbs respond by doing a series of movements. In the experiment, the satellite transmits data to the earth, and the main control center would collect and analyze the data before giving orders to sub-control centers about what to do next," said Zhang Wenzhuo, a researcher at the control center.

Researchers said the experiments will be conducted at night to avoid disturbance from strong sunlight, and so far many tests have been run at night. However, they say the ultimate goal is to achieve absolute secure information transmission around the clock.

 

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Researchers from the Key Laboratory of Quantum Information of the Chinese Academy of Sciences in Hefei, capital of east China's Anhui Province, have made a new achievement in the research of the semiconductor quantum chip, the "brain" of quantum computer in the future.

The successful development in the research of semiconductor quantum chip has paved the way for quantum logic operations and information processing. In addition, the researchers are updating the technology for quantum memory control.

"Our next development direction is to make the quantum memory device small and neat so as to extend its lifespan. Our final objective is to make it a device as convenient to use as a classic and portable USB flash disk so that quantum state information can be transmitted over great distances," said Zhou Zongquan, a researcher of the lab.

 

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Chinese scientists have finished equipment joint debugging for the world's first quantum-communications network are ready to officially put it into use within the year. The equipment system of the 2,000-kilometer Jing-Hu quantum-communications network connecting Beijing (Jing) and Shanghai (Hu) has run smoothly for over six months. The line passes by the country's major secret communication network nodes in Jinan and Hefei cities.

More than three fourths of the construction of the main network of Jing-Hu line has been completed. Scientists and engineers have been undertaking the work of offline installation. Once put into use, the quantum-communications network will allow communication under highest level of protection over long distances including phone calls, video calls and emails, said Chen Yu'ao, the project's chief engineer.

"As our computing power gets better, the methods once considered safe are no longer safe. Specially, when it comes to quantum computation, the public-key cryptography is no longer safe. Quantum computing perfectly annotates the saying 'when God closes a door, He opens a window.' That is to say, when this is such a powerful spear as quantum computation, the method also provides a shield to guard against possible security breaches that come along with this type of computation," said Chen Yu'ao, chief engineer of the Jing-Hu quantum-communications network.

Safety of the quantum-communications security technology is decided by the subatomic properties of the photons. Different from conventional data-encryption methods that use 0s and 1s to encrypt and decrypt information, quantum communication allows users to code information into the specific quantum state of photons, the smallest energy unit in this type of communication. As the act of eavesdropping inevitably alters the quantum state, users on both ends of the quantum-communications network will be alerted when there is a security breach.

Despite the difficulty of sending photons over long distances, Chinese scientists have successfully increased the information transmission rate to over 100 kilometers in the ground network, which, together with a quantum satellite scheduled to be launched, will complete the world's first integrated quantum-communications system.

 

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The Chine se banks and governments will resort to the quantum encryption system to transmit important safety data after the world's first optic fiber network Bejing-Shanghai line opens in late 2016.

At present, China has taken the lead in transmitting quantum encryption data in the financial field in the same city. The Industrial and Commercial Bank of China (ICBC) is the country's first financial company using quantum encryption.

"All our equipment here at this room is for quantum communications. The big one is used to generate secret keys and the small one to send data. All our data can be sent to another center which has the same equipment as ours after this one generates secret keys, so the two centers can exchange data safely," said Zhang Zhuhong, head of Internet at ICBC date center in Shanghai.

For example, a person has a safe and he needs a key to open it. It's the quantum state that is responsible for sending a secret key. If the key were intercepted by others, the receiver would be aware of that, and a new key would be sent again.

The quantum optical fiber communication network project, the Beijing–Shanghai line, was launched in 2013. The line will cover a total length of over 2,000 kilometers, connecting a network of numerous cities including Beijing, Jinan, Hefei and Shanghai. It will be the world's first wide-area optic fiber quantum private network.

 

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Locature in north China's Hebei Province, the Xinglong Observatory of the National Astronomical Observatories is one of the five observatories that will conduct quantum communication research jointly with the quantum satellite set to be launched this month.

The task of this particular observatory, according to a researcher, is quantum key distribution, which enables two parties to produce a shared random secret key known only to them. The key can then be used to encrypt and decrypt messages so as to guarantee secure communication.

The quantum key distribution will be finished in a three-floor building of the Xinglong Observatory. On the top floor is a one meter diameter telescope; the signal processing system locates on the second floor; and the newly developed integrated control system is on the first floor.

"The telescope is capable of conducting high speed rotation, which enables it to follow the satellite and receive the signal beacon. Then the received satellite beacon will go through the primary mirror and the second mirror, plus the third mirror to change the direction, to finally reach the quantum terminal," Wang Jianfeng, chief designer of the building and reconstruction of the ground observatory of China's quantum communication research , explained the mechanism to journalists.

The received photons will then be transmitted to an optical terminal to be analyzed based on the polarization properties of the photons. The signal processing system on the second floor will then receive the photons through several optical fibers and record the data.

 

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Chinese scientists at the Nanshan Observation Station in the Xinjiang Uygur Autonomous Region are retesting the astronomical telescope to ensure it could accurately capture the quantum to be sent by the satellite that is about to be launched in a few days.

The astronomical telescope was built last year specifically for quantum communication experiment. The tasks it carried out before were mostly measurements of simulated quantum satellite sent. Now it is being put into real action.

"It will communicate with the on-orbit satellite. The core of the communication is to establish a link that will provide a guarantee for quantum communication. The satellite has an orbit and we will capture the satellite through the predicted orbit, and we shall establish a link between them by the pre-designed orbit and the accurate direction indicated by the astronomical telescope and let them send signals to each other, thus completing the communication," said Wang Qiang, associate professor at the Institute of Optics and Electronics of Chinese Academy of Sciences.

The University of Science and Technology of China group, with an average age of 28, is in charge of the ground task of the Nanshan Observation Station.

"Currently we must ensure the telescope in a good state. We must retest every indicator to make sure it could complete the satellite task smoothly," said Li Dongdong, a doctorate student of the University of Science and Technology of China.

 

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The Lijiang ground station is not only the satellite ground station which has taken the shortest time to set up in China, it will also take on part of China's groundbreaking experimentation of a cutting-edge technology - quantum communication or quantum teleportation, all by tracking a satellite for precision.

Situated 3,200 meters above sea level, the Lijiang ground station consists of a 1.8-meter-aperture telescope, a quantum terminal and an integrated control system.

"We've transformed an existing 1.8-meter-aperture telescope. It's the one with the highest tracking precision in China. It gives in a less than 12-centimeter shake while tracking an object 500 kilometers away in space. Such a precision is more than enough for communication," explains He Dong, deputy chief designer of telescope subsystem in the quantum scientific experimentation.

During the upcoming experimentation, the Lijiang ground station is assigned to coordinate with another ground station in west China to do a two-direction entangled quantum distribution. When the quantum satellite travels past over this part of China, it sends down entangled photons to these two ground stations for them to receive. The ground stations have to be highly precise with their telescopes in targeting and tracking the passing satellite, to complete the experimentation."

"We at ground station are demanded to point our telescope to the target precisely and to lock our telescope onto tracking the target steadily. We have only five minutes to do both. We'll depend on the capability of our telescope, its tracking precision, to keep the target steadily in our field of view. By so doing, we can maintain the link, through which the satellite will send the entangled photons," He Dong explains further.

"Our telescope has already acquired this capability, after we have done all adjustments and a trial tracking on the moon of a sun. We are now waiting for this experimentation of quantum communication and quantum entanglement distribution," the deputy chief designer adds.

 

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China's Shenzhou-11 spaceship arrived at the Jiuquan Satellite Launch Center in northwest China on Saturday, just two months before it carries two astronauts into space for a 30-day mission.General assembly and testing will begin at the center ahead of the launch scheduled for mid-October, said a statement by China's manned space engineering office.The astronauts selected for the mission are both male and have been undergoing intense training, the statement said.

 

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Shenzhou-11 spacecraft will take on two major missions of ferrying astronauts and verifying space station technologies. "Because it will be the last manned spacecraft flight prior to the space station launch, we have carried out some verifications adapted to the space station to see whether the technologies will meet the requirements. This is the main objective," says Zhang Bainan the chief designer. "We have made enormous strides in technologies [from Shenzhou-1 to Shenzhou-9 spaceships which accomplished experimental flights]. The technical conditions have become mature when we launched the Shenzhou-10 spacecraft," adds Zhang Bainan.