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.

SpaceX launch scheduled for Wednesday will carry replacement crew for astronauts who have been stuck on the International Space Station since their troubled Starliner mission.

Tense, public squabbles between SpaceX CEO Elon Musk and NASA have stirred the space industry, but behind the scenes, space science has continued business as (almost) normal.