During his nearly year-long mission aboard the International Space Station, former NASA astronaut Scott Kelly garnered a large measure of attention for his Ironman feats, including setting a US record for the cumulative amount of time in space—520 days. Jeff Williams may be less well-known, but he will quietly become NASA’s new spaceflight Ironman on Wednesday morning.

Williams has reached 520 days after a Space Shuttle mission in 2000, two previous increments on the Space Station in 2006 and 2009, and he’s now nearing the end of his third mission to the Space Station. When he lands on September 6, Williams will have spent a cumulative 534 days in space, two weeks longer than Kelly’s total. (No NASA astronaut can equal the duration records of Russian cosmonauts. The all-time leader, Gennady Padalka, has spent 879 days in space over five missions).

In many ways, Williams' tenure at NASA has paralleled the development of the Space Station. After a decorated career as a test pilot, Williams was selected to become an astronaut in 1996, a time when the United States and Russia were in the formative stages of planning and developing the station as an international project. His first spaceflight, in May 2000, was just the third shuttle flight devoted to station construction. It helped pave the way for the first crews to live aboard the station, beginning in November, 2000. Williams is also the first NASA astronaut to spend three separate increments aboard the orbiting laboratory.

During an interview with NASA’s Rob Navias in June, Williams was asked to reflect on his duration record. “I think we would all agree that it’s an honor to spend any day in space, certainly to have accumulated that time is an honor for me,” Williams said. Then the astronaut made clear that he didn’t view his record as a personal achievement but rather as a testament to the station itself. “To be a part of it at the beginning, the middle, and now when it’s in the full utilization mode, and really stepping up in terms of the greater scientific community, that’s really the bigger story to me personally. This is the most significant technological achievement, in my opinion, in history.”

It is also true that, like his predecessor Kelly, Williams’ duration record may be short-lived. Another NASA veteran, Peggy Whitson, is scheduled to launch to the Space Station on November 16, 2016. Like Williams, Whitson will be making her third stint aboard the station, and with 376 days already in the bank, she will likely end up with a total of 555 to 560 days in space, putting her several weeks beyond Williams. At that point, NASA wouldn’t have a new Ironman to celebrate—rather an Ironwoman.