In preparation for the upcoming launch of SpaceX’s Falcon Heavy spacecraft, NASA explained the exact function of the Deep Space Atomic Clock (DSAC) payload through a Reddit forum. According to the space agency, the newly developed device will be able to help future missions navigate more efficiently and accurately in space.

NASA first announced the mission involving the DSAC earlier this Month. On June 18, the space agency announced via Twitter that it will host an online public forum to answer questions regarding the upcoming mission.

One of the questions asked by Reddit users to NASA was related to the function of the atomic clock and how it will serve as a navigational tool in space.

According to the space agency, the DSAC, which is about as big as a toaster, will function like a cosmic GPS tool. Previously, spacecraft depended on Earth-based atomic clocks for navigation. However, due to the distance between the spacecraft and the location of the clock, the exchange of information can get delayed and even distorted.

“Our ability to navigate spacecraft throughout deep space is driven by the ability to very accurately measure the length of time it takes a signal to travel from a ground antenna to the spacecraft – knowing how fast that signal travels and how long that trip took, we can compute the distance to the spacecraft,” NASA explained.

“The Deep Space Atomic Clock will give us that accurate and stable time-keeping capability in a package small enough and robust enough to fly into space – which means now we can use ‘one-way tracking,’ in which the signal is sent directly from the ground antenna to the spacecraft,” the agency added.

NASA is targeting to use the DSAC in its future missions to Mars. According to a statement from the space agency, by deploying a handful of spacecraft with atomic clocks onboard near Mars, it will be able to create a navigational network similar to GPS on the Red Planet. This network can be used to provide real-time directions to both humans and rovers on Mars’ surface.

NASA’s DSAC is set to launch aboard the Falcon Heavy on June 24. Aside from the atomic clock, SpaceX’s rocket will also carry other experimental payloads such as the solar-powered LightSail spacecraft.