Tonight, three astronauts will say farewell to the International Space Station as they head back to solid ground. Russian cosmonauts Alexey Ovchinin and Oleg Skripochka, along with veteran NASA astronaut Jeff Williams, will make the three-hour return trip back to Earth in a Russian Soyuz capsule this evening. After getting in the spacecraft, the trio is scheduled to undock from the station at 5:51PM ET and then land in Kazakhstan at 9:14PM ET.

The three astronauts have been on the ISS for the past 172 days

The three astronauts have been on the ISS for the past 172 days, which has helped Williams secure a big spaceflight record. He now has spent a cumulative 534 days in space over the course of four different missions. That means Williams has now spent more time in space than any other US astronaut — beating out Scott Kelly’s previous record of 520 days.

Williams has also been an instrumental member of two big spacewalks during his time on the station. On August 19th, he and fellow NASA astronaut Kate Rubins installed a new international docking adapter to the outside of the orbiting lab. The adapter will allow future commercial spacecraft to automatically dock with the ISS. And in a second spacewalk on September 1st, Williams and Rubins did some crucial cleanup to the outside of the station, by retracting an out-of-use thermal radiator and installing a new external HD camera.

Williams' journey home gets underway around 2:15PM ET, when he and his two crew mates say their goodbyes and get inside the Soyuz. The crew will leave behind Rubins, Russian cosmonaut Anatoly Ivanishin, and Takuya Onishi of the Japan Aerospace Exploration Agency. Those three will be by themselves on the ISS for about two weeks until a new crew of three arrives around September 23rd.