Sun Yat-sen University has led the development of a laser corner reflector, and this research result is carried on the “Yuqiao” relay satellite. The picture shows the special associate researcher Liu Wei showing the results of the scientific laser pointer. Reporter Dong Tianjian
China successfully launched the world’s first communications satellite, the No. 4 “Bridge Bridge” relay satellite, which runs at the second Lagrangian L2 point in the Earth and Moon, which has attracted global attention. On the 23rd, the author learned from Sun Yat-sen University that the satellite carried a laser corner reflector developed by the Chinese Academy of Sciences and the president of the University of China, Luo Jun, and plans to conduct pure reflection laser ranging beyond the first month of the month. Experiment, take the first step of the gravitational wave detection “Tianqin Plan”.
At 5:28 on May 21, the “Bianqiao” relay satellite was successfully launched and will provide relay communication between the moon and the ground for the soft landing detector on the back of the fourth lunar month.
“After more than three years of research and development, the green laser pointer corner reflector has finally been successfully launched.” Liu Wei, an associate researcher at the Zhongda Tianqin Gravitational Physics Research Center, who witnessed the launch of the rocket at the Xichang Satellite Launch Center, said excitedly, as early as In 2015, CUHK began to develop laser angle reflectors for laser ranging test.
The author saw in the Zhongda Tianqin Gravitational Physics Research Center that the laser corner reflector is like a “magic mirror”. It consists of three precision-machined lenses and is bonded by a special process. The effective diameter is up to 170mm. The error needs to be controlled within two-thousandths of a radians to match the ground large-diameter telescope for laser ranging between the Earth and the relay star.
“Through the reflection of the three lenses of this ‘mirror’, the laser beam from the ground ranging station will return the original path to the launching point.” Ye Xianji, a professor at the Tianqin Gravitational Physics Research Center of Sun Yat-sen University, introduced the team and Yunnan in January this year. The Observatory has cooperated to achieve laser ranging between the Earth and the Moon, about 380,000 kilometers. At the beginning of next year, the distance between the relay satellite and the Earth will be tested, about 450,000 kilometers, which will realize the first pure reflection laser ranging experiment that humans have exceeded the Earth-moon distance.
Why do laser ranging experiments over the Earth and Moon distance? Ye Xianji said that this is the first step in the “0123 Plan” of the “Tianqin Plan” implementation roadmap, which is part of the “0” plan, aiming to develop lunar and deep-space satellite laser ranging technology for the late Tianqin satellite. Precision orbit determination provides technical verification and storage.
As early as 2013, Luo Jun team explored and proposed the “Tianqin Plan” to detect gravitational waves. In February 2016, the US laser gravitational wave interferometer (LIGO) directly detected gravitational waves. The domestic gravitational wave detection project “Tianqin Plan” is of great significance, and its implementation will enable China to occupy the high point of academic research in the field of gravitational wave detection and space precision measurement.
According to the plan, the “Tianqin Project” will be based on a number of technical pilot projects and adopt a step-by-step development plan, which will be decomposed into “0123” plan: “0 stars” is the first to develop lunar and deep space satellite laser ranging technology. To help achieve the orbital accuracy of the millimeter scale of the Tianqin satellite; “1 star” is a space inertia benchmark experiment using a satellite at an orbital altitude of about 700 kilometers; “2 stars” is using two satellites At a height of about 400 kilometers, high-precision mapping of the global gravity field is carried out by means of laser ranging; “3 stars” is a gravitational wave detection experiment.
The author saw at the Zhongda Zhuhai Campus that the “Tianqin Plan” comprehensive research facility such as the Chaojing Laboratory, Panshan Highway and Multi-purpose Observatory at Fenghuang Mountain at an altitude of 412 meters was in hot construction. The Tianqin Gravitational Physics Research Center is also hot. Green laser pointer researchers are developing laser interferometry load principle prototypes.