The spacecraft, SPHEREx and PUNCH, had been expected to launch on a SpaceX rocket on Saturday. Two NASA missions will have to wait longer for a launch aboard a single rocket. Both aim to unravel mysteries about the universe — one by peering far from Earth, the other by looking closer to home.

NASA and SpaceX on Friday will count down to a long-awaited crewed rocket launch that will allow them to bring home U.S. astronauts Butch Wilmore and Suni Williams, who have been stuck on the International Space Station for nine months.