On June 24, the SpaceX Falcon Heavy rocket is scheduled to take off, and it will take with it the most precise clock in the universe. The Deep Space Atomic Clock, created in NASA’s Jet Propulsion Laboratory, is an ultra-precise device that is about 50 times more stable than your average GPS satellite clock. “A clock that is off by even a single second could mean the difference between landing on Mars and missing it by miles,” NASA wrote in a statement. Scientists at NASA have been perfecting time for 20 years to create this clock, which only loses one second every 9 million years. The device, which uses mercury ions, will help spacecrafts navigate more autonomously by allowing the spacecraft to receive signals from Earth and then using those signals to calculate its location using an onboard navigation system. This means the Falcon Heavy may soon be able to navigate through space on its own, without much interference from Earth.