Once a nuclear submarine entered a deep, massive ocean such as the Pacific, it used to be believed that it would remain undetectable until it surfaced. But a space-based submarine detection platform could locate it with unparalled precision.The two-man Shenzhou XI spaceship that blasted off from the Jiuquan Satellite Launch Center in Inner Mongolia on Monday 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 that will stay accurate for a billion years and be able to measure gravitational waves at the atomic level. The crew will spend 30 days in lab as part of bigger plan to build an international space station in six years. One task on their to-do list could be detecting and tracking nuclear submarines from space, using a technological breakthrough achieved by Chinese scientists.
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, some measuring more than 170 meters in length and displacing 48,000 cubic metres of water. When they cruise several hundred metres below the ocean’s surface they generate gravitational ripples that the detector could monitor and analyze to locate and follow the submarine.
China could be the first nation to use cold atom interferometry to detect submarines, according to a researcher at the Beijing-based China Academy of Space Technology, which has initiated and designed most of China’s space projects. The cold atom interferometer would be part of a super-cold atom laboratory in the space station’s experimental module.
Professor Tu Liangcheng, who has studied the precise measurement of gravity at Wuhan’s Huazhong University of Science and Technology, said the Chinese government had substantially increased funding for submarine detection technology in recent years. “There is a shift in the navy’s attitude to submarine warfare,” said Tu, who has been involved in military research projects.
But funding for submarine-hunting technology, including gravitational measurement, had now increased significantly, Tu said. The change reflects China’s ambition to develop a “blue-water” navy able to protect its national interests along important maritime trade routes spanning the globe.
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.
“Now we have enough money, and China’s strength in this field of research in on par with the US and Europe,” Tu said. “But the pressure is high, there is high expectation of a quick breakthrough, and we are short of hands.”
Besides the cold atom interferometer, China might consider other unconventional ways to detect submarines.
Nuclear submarines’ fission reactors produce neutrinos, extremely small particles can pass through materials such as water and walls without effort, potentially exposing a submarine’s location.
China has built some of the world’s largest and most advanced neutrino detectors, one at Shenzhen’s Daya Bay nuclear power plant and the other at a hydropower station in Sichuan, which at 2.4km below the earth’s surface is the world’s deepest underground laboratory.
Cao Jun, the researcher who led the Daya Bay neutrino detection project, said that detecting the elusive particles from a source 50km away, using current technology, required a detector weighing 20,000 tons. But new neutrino detection technologies were emerging, which might satisfy the military’s need for a portable platform.
A future technological breakthrough might enable scientists to develop neutrino detectors that could be placed on ships or space stations, Cao added.
The US and Europe also launched cold atom interferometer projects, but they were either cancelled or delayed, mainly due to funding shortfalls, and some Western scientists have expressed interest in joining the Chinese project.
China has told the European Space Agency that there could be a place for European astronauts on the Chinese space station, and some European astronauts have started learning Chinese to prepare for the trip.