NASA astronaut Chris Williams flexes his muscles while on a spacewalk in this image snapped by fellow astronaut Jessica Meir on June 30, 2026. (Image credit: NASA/Jessica Meir)Mid-spacewalk, one NASA astronaut had to take a moment to show off his muscles. What is it? NASA astronaut Chris Williams recently left the confines of the International Space Station for a 7-hour-and-20-minute spacewalk with fellow astronaut Jessica Meir. This was Williams' second spacewalk and Meir's fifth.In a moment of fun, Williams flexed his muscles for a photo snapped by Meir during the strenuous spacewalk. With a big grin on his face, visible even through his spacesuit helmet, Williams raised his arms in a classic Muscle Beach pose as planet Earth glowed hundreds of miles beneath him.But the pair of astronauts weren't playing around in space; this spacewalk had a serious purpose. On June 30, Williams and Meir ventured into the void to replace a wrist joint on the space station's Canadarm2 robotic arm that had been malfunctioning.Canadarm2 has been operating for over 25 years, so it makes sense that every once in a while it needs a repair or upgrade. After making this swap, the old wrist joint will be sent back to Earth to be fixed in case it needs to be used as backup in the future.Why is it incredible?Williams' demeanor in this photo makes it seem like spacewalks are fun, or even easy. But his smile and playful pose for the camera are a major contrast to the incredible strength, stamina and careful work that it takes to complete a spacewalk.From preparation to suiting up, and doing incredibly precise work with a spacesuit on while floating in the vacuum of space while tethered to the space station, spacewalks are incredibly hard work. Williams may have been having a fun moment with Meir showing off in this photo, but the pair of astronauts were certainly using their muscles to get a tough job done.