SpaceX delayed its seventh test launch of Starship by 24 hours on Wednesday due to weather concerns, pushing back an experiment that will feature the spacecraft’s first payload deployment test in what may be the latest milestone for the Elon Musk-owned aerospace company as it develops reusable rockets.

While Suni Williams and Butch Wilmore’s situation is unusual, their return trip will be pretty routine, as they were already slated to fly home on a SpaceX capsule as part of a scheduled crew rotation.