(a) "Shenzhou XI spaceship that blasted off from the Jiuquan Satellite Launch Centre in Inner Mongolia on Monday [Oct 17] morning will soon dock with the Tiangong-2 space laboratory, launched last month, which is carrying the world's first space-based cold atom clock.
"The ultra-accurate timepiece shares its core technology with cold atom interferometers, which can measure tiny changes in gravitational pull with unprecedented sensitivity, and one of the devices, to be built and put on the Chinese space station, could potentially be used to track nuclear submarines.
"Nuclear submarines can be massive, with the largest measuring more than 170 metres in length and displacing 48,000 cubic metres of water, and when they cruise several hundred metres below the ocean’s surface they generate many gravitational ripples. An extremely sensitive detector could catch and analyse the invisible ripples to locate and follow the submarine.
"Using cold atom interferometry to detect submarines is a controversial technology * * * China could be the first nation to do so, according to a researcher at the Beijing-based China Academy of Space Technology [(CAST); 中国空间技术研究院; based in Beijing]
(b) "Professor Tu Liangcheng 涂良成, who has studied the precise measurement of gravity at Wuhan's Huazhong University of Science and Technology 华中科技大学 * * * Tu said the Chinese navy desperately wanted to be able to track foreign nuclear submarines, but it was 30 years behind the capabilities of the United States when it came to submarine-detection technology. * * * There are many ways to measure gravitational variations.