CHINA has recently launched the construction of two 40-meter-aperture radio telescopes in Shigatse, located in Southwest China’s Tibet Autonomous Region, and in Changbai Mountain area in Northeast China’s Jilin Province, respectively. The two telescopes, developed by Shanghai Astronomical Observatory (SHAO) under the Chinese Academy of Sciences, are expected to offer technical support for the country’s lunar and deep-space probe missions in the future. Zheng Weimin, a researcher at SHAO, said that the two telescopes will further enhance the observation capability of the very-long-baseline interferometry (VLBI) network in China. “VLBI is a radio interferometry technology that can be used to obtain fine radio images and precise positions of cosmic objects, and can perform high-precision positioning of deep space probes,” Zheng said. Unlike conventional techniques, the VLBI technique can combine observation signals from different telescopes for joint processing, he explained. “In other words, it is a ‘virtual telescope’ with a size equal to the maximum separation between the telescopes,” Zheng added. The current VLBI network in China comprises four observatories across the country, located in Beijing, Shanghai, Urumqi and Kunming. The maximum distance from the current telescope baseline in China is about 3,200 kilometers from Shanghai to Urumqi. However, after the completion of the two new telescopes, the maximum distance from the new baseline in China will be about 3,800 kilometers from Changbai Mountain to Shigatse, which will increase the highest angular resolution by 18%, Zheng said. “That’s why it is necessary to build separate telescopes at Shigatse and Changbai Mountain,” he said, adding that the two new telescopes will further extend the VLBI network. The inclusion of the two new telescopes will also allow simultaneous observation of two targets in different celestial regions, providing stronger support for the lunar and deep-space probe missions in the future. (Xinhua) | 