The most accurate clock in space will start within a few days and start building highly synced networks from the best clocks on the planet. However, the project will only work for a few decades, and only a few years before it burns out as hair removal for the International Space Station at the end of the decade.

Atomic Clock in Space (ACES) is a European Space Agency (ESA) mission that generates time signals with unprecedented accuracy and transmits them to nine ground stations via lasers as they pass over the overhead at 27,000 km/h. This watch network is very closely synchronized and provides extremely accurate timekeeping around the world.

As a result, ACES can test Einstein’s theory of general relativity. This states that the passage of time is influenced by the strength of gravity and is very accurately affected. It also supports all research, from dark matter to string theory.

ACES is scheduled to be released on April 21st for the SpaceX Falcon 9 rocket from Kennedy Space Center, Florida. Upon reaching the ISS, the Canadarm2, the Canadian Space Agency’s robotic arm, attaches it to the outside of ESA’s Columbus Laboratory, where it remains in a vacuum in the space.

The package actually consists of two clocks. One is called SHM, which can be kept stable for a short period of time. Together, these watches are extremely accurate, losing less than a second for over 300 million years. It is 10 times more accurate than a GPS satellite clock.

Pharaohs are basically modeled on Paris’ atomic clocks that occupy the entire room. Its technology was no more than a cubic meter, miniaturization to something that could allow rocket launches and survive the harshness of living in space was by no means a feat.

To generate an accurate clock signal, the pharaoh expels a fountain of cesium atoms cooled to absolute zero and observes its interaction with the microwave field. On Earth, devices of 3 meters are required, but at microgravity, these atoms move slowly and are sprayed into smaller fountains, making them much smaller.

Simon Weinberg The ESA says that simply placing a teaspoon close can create an electromagnetic field strong enough to destroy the watch. “Just putting it in context, it’s better than the 100 million seconds we’re trying to measure here,” says Weinberg. “So it’s one hell of challenging work.”

The ACES concept dates back to the 1990s and was originally scheduled to be released at the Space Shuttle, which retired in 2011. Once you reach space, the first signal will not reach the Earth-bound clock for a year and a half. It takes about six months to outsource the device.

The ACES then operates until 2030, after which the ISS intentionally crashes into the Earth’s atmosphere and burns out. By that point, the new ultra-precision watch known as optical watches likely have created an atomic clock that has become obsolete on Earth, but by then it may not be small or robust enough to be used in space.

At one point, Weinberg says the ESA is aiming to launch a new generation of ACEs to replace what was lost in the ISS, whatever the technology was most appropriate back then. “We’ll go a long way from doing it, and we have to gather support, fundraising and more to make sure that happens.”