On 24 June 2019, NASA is sending an atomic clock into space. Not just any old atomic clock, either. It’s up to 50 times more accurate than the atomic clocks aboard GPS satellites, its precision only changing by one second every 10 million years.

It’s only the size of a toaster, yet it could revolutionise deep-space travel.

It’s called the Deep Space Atomic Clock, and the next year will be crucial to its development, with NASA monitoring its performance as it orbits Earth at an altitude of 720 kilometres (447 miles) — nearly twice the distance from Earth as the International Space Station. It’ll be launched aboard SpaceX’s Falcon Heavy rocket.