Tiangong atom clock 'accurate'

The Chinese Academy of Sciences says that an atomic clock has lost the equivalent of only one second in 30 million years during its two years in orbit on Tiangong-2, China’s space lab.

Unlike most atomic clocks, this clock uses cold atom technology to ensure its ultra precision. Hot atom clocks have almost reached their limits in regard to long-term stability. Modern time-keeping systems on Earth and the global navigation satellite system rely heavily on atomic clocks.

The high accuracy of the cold atom clock is attributed to the microgravity environment in space as well as the coldness of the atoms the clock uses.

Under microgravity conditions, cold atoms are pushed by lasers. By observing their performance, it is possible to obtain more precise time signals than on Earth.