The "Tianqin Plan" is the Chinese Academy of SciencesLuo JunAcademicians in March 2014Huazhong University of Science and TechnologyProposed in an international conference of[1], July 2015Sun Yat-sen UniversityFor a scientific research plan launched by Sun Yat sen University and Huazhong University of Science and Technology, a research team is being set up to carry out preliminary research on the tasks of China's space gravitational wave detection plan, formulate the implementation plan and roadmap of China's space gravitational wave detection plan, and propose the "Tianqin" spaceGravitational waveDetection plan.
Gravitational wave research plan will take 20 years to complete the "Tianqin Plan" with a total investment of about 15 billion yuan.The Zhuhai Campus of Sun Yat sen University is building the ground infrastructure needed for gravitational wave research, and has started the construction of the tunnel hyperstatic laboratory and the ground station infrastructure for laser ranging.[2]
The "Tianqin Plan" has been officially launched in July 2015, and some key technology research has made concrete progress and is in the process of project approval.[3]
On February 21, 2016, Sun Yat sen University held a seminar to promote the implementation of the "Tianqin Plan" and released its roadmap "0123 Plan", which will take 15 to 20 years to launch satellites into the sky.[4]
Gravitational waveIt is the fluctuation of accelerating mass in time and space, and is also compared to the "ripple" of time and space.[2]
According to Einstein's Theory of Relativity, the huge movement of celestial bodies in the universe will distort space-time and spread like waves, which is called gravitational waves.In 2016, scientists from many countries first detected gravitational waves.
In April 2018, China's gravitational wave detection plan was actively implemented. Academician Luo Jun was the key figure of the gravitational wave detection "Tianqin" plan.In Wuhan, Hubei Province,Huazhong University of Science and TechnologyIn the air raid shelter under Yujia Mountain, Academician Luo Jun and his team are developing a gravitational wave detection device.[7]
Plan overview
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Zhongshan University Zhuhai CampusThe ground research infrastructure required by the "Tianqin Plan" will be built, and based on this, the national major scientific engineering projects facing the major national needs and the frontier of scientific foundation will be carried out.The infrastructure construction of cave hyperstatic laboratory and laser ranging ground station has been started, and some key technology research has also made concrete progress.The promotion of the Tianqin Program will make Sun Yat sen University one of the important academic research centers in the field of gravitational wave detection and precision space measurement in the world, and become a research base to promote a series of subsequent physical experiments in precision space measurement.[8]
It is reported that the "Tianqin Program" experiment itself will consist of three identical satellites (SC1, SC2, SC3) to form an equilateral triangle arrayInertial sensor, laser interferometry ranging and other core technologies to "sense" gravitational wave signals from the universe and explore the secrets of the universe.The three stars, shaped like a harp set up in space, can listen to the "sound" of gravitational waves in the deep universe, which is the "Tianqin Plan" for space gravitational wave exploration proposed by Chinese scientists.[9]The satellites themselves perform high-precision drag free control to suppress external interference such as solar wind and solar light pressure, and the distance changes caused by gravitational waves are accurately measured by laser between satellites.The important target of Tianqin is the gravitational wave generated by an ultra compact double white dwarf system RXJ0806.3+1527 with a period of only 5.4 minutes.[4]
Tianqin first requires three satellites to enter a pre selected orbit very accurately.In order to steadily achieve the goal, according to the number of satellites required for each mission, the "0123" plan roadmap has been formulated. Tianqin plan will first develop the laser ranging technology of moon and deep space satellites to help achieve the millimeter level orbit determination accuracy of Tianqin satellite;The space equivalence principle test experiment, the next generation gravity satellite experiment, etc., and finally the Tianqin space gravitational wave detection experiment:Detecting gravitational waves。[10]
In May 2020, deputy to the National People's Congress and chief scientist of China's Space Gravitational Wave Exploration Tianqin ProgramLuo JunAcademicians revealed that the proposal for the "Tianqin II" project had been submitted to the relevant superior departments before the Spring Festival, and all work was progressing steadily. Breakthroughs were made in key technologies, some of which were mature and had been tested on the "Tianqin I" project.“Tianqin No. 2”It is planned to launch around 2025[11]。
Important features
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LIGO in the United States
Compared with the LIGO (Laser Interferometric Gravitational Wave Observatory) in the United States, the Tianqin plan will have optical auxiliary means for gravitational wave detection. In addition, unlike the explosive gravitational waves detected by LIGO in a short time, the continuous gravitational waves detected by Tianqin in the low frequency band can be continuously verified.
The "Tianqin Plan" is not just basic research. The key technologies developed by the "Tianqin Plan" can be used in many fields, such as accurate measurement of the earth's gravity field, so that people can more deeply understand the distribution and changes of the earth, water resources and mineral resources.Another example is the accurate measurement of distance, ranging from the distance between two satellites to changes of an atomic scale.[10]
implementation phase
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The "Tianqin Plan" will be implemented in four phases: the first phase will complete the ground auxiliary facilities of the Tianqin Plan, such as the moon/satellite laser ranging system and large laser gyroscope;In the second stage, key technologies such as non towing control, spaceborne laser interferometer and experimental verification of space equivalent principle were completed;In the third stage, the verification of key technologies such as high-precision inertial sensing, intersatellite laser ranging, and global gravity field measurement will be completed;The fourth stage is to complete all the key technologies required for space gravitational wave detection, and launch three earth high orbit satellites for gravitational wave detection.[12]
It will take about 20 years to complete all four sub plans, with an investment of about 15 billion yuan.
international co-operation
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The "Tianqin Plan" will become an international cooperation project led by China.In 2016, in addition to many universities and research institutions in China, several core members of the LISA program research group were very willing to cooperate. Top professors from Germany, Italy and France also wanted to become partners or consultants. Several professors from Moscow University in Russia have participated.[10]
Significant progress
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On September 27, 2018xiangshan science conference The latest news about the "Tianqin Plan" came from the S45th academic seminar.A number of key technologies of the "Tianqin Program" have made significant progress, including inertial sensing, laser interferometry ranging, no drag control, satellite platform and other major technologies. These technologies will continue to enter the on orbit verification phase.
Tow free control technology is one of the key technologies to realize the space gravitational wave detection plan. In short, it is to make the inspection quality carried in the satellite "get rid of" various interference from the external environment, so that the inspection quality can drift freely and unimpeded.School of Physics, Huazhong University of Science and TechnologyProfessor Zhou Zebing introduced that the "Tianqin" drag free control technology has made a breakthrough in the laboratory and is moving forward according to the research plan.
The "Tianqin Plan" and the European LISA Plan are the few space gravitational wave detection plans in the world based on mature designs and schemes. Both plans are pushing forward against the clock.The main difference between the two plans is that their designed orbits are one around the earth and one around the sun, and their detection bands are slightly different."If the detection band of the Tianqin Program is about 10 times higher than LISA, the two groups of gravitational wave detectors can complement each other," said Ye Xianji, a professor at the Tianqin Center of Sun Yat sen University.[9]
