NASA and SpaceX plan to return one Crew Dragon spacecraft from orbit on Monday evening and launch another two days later, on Wednesday night.

The agency’s crew flight plans have been in flux since just before Halloween, when weather concerns and then a “minor medical issue” with one of the four astronauts on the Crew-3 mission delayed the rocket’s launch from October 31 into November.

Since that time, NASA and SpaceX, which provides the Crew Dragon spacecraft and Falcon 9 launch system, have been evaluating a host of issues in order to determine how best to launch the Crew-3 mission and return the four Crew-2 astronauts from the International Space Station.