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.

During its two-year mission, the four satellites of PUNCH (Polarimeter to Unify the Corona and Heliosphere) will study the sun’s outer atmosphere, the corona, to determine how it transitions ...

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.