THE International Space Station will soon host the most accurate clock ever sent into space. It will allow for better synchronisation of clocks on Earth and also probe exotic physics.

The experiment, called Atomic Clock Ensemble in Space (ACES), will be built by EADS Astrium and is scheduled to fly to the space station in 2014, the European Space Agency announced last week. It will keep track of time by measuring the frequency of microwaves absorbed by cooled caesium atoms.

On Earth, the accuracy of caesium clocks is limited by gravity. The atoms are cooled by using lasers to slow …