We’ve seen not one but two delays now for SpaceX’s Crew-3 mission. While we hope for a speedy recovery for the crew member who suffered from the “minor medical issue,” we have to ask, What does this mean for the return home for Crew-2, the current residents of the ISS?
SpaceX’s Crew-3 is delayed to no sooner than Saturday evening, but there is a good chance the weather will be unfavorable again. As a result, another delay could push the launch of Crew-2’s replacements to Sunday or into next week.
Usually, the handoff between NASA crews occurs while both crews are on the station. This is called a direct handoff and temporarily brings the ISS capacity to 11. Then, a few days later, the previous crew begins their journey home by undocking their SpaceX Dragon spacecraft and deorbiting. This trip ends in splashing down off the coast of Florida.
A line in NASA’s blog post about the most recent delay may point toward NASA looking at alternative timelines for Crew-2, which means a departure of Crew-2 before Crew-3 has a chance to relieve them in person.
Mission teams are reviewing options including both direct and indirect handovers for the upcoming crew rotation at the microgravity laboratory.
“Indirect” refers to the departure of Crew-2 from the ISS before Crew-3 has arrived, most likely before they even launch.
Why might NASA not wait for Crew-3 to launch?
The apparent solution is to push back the departure of Crew-2 until Crew-3 arrives. Direct handoffs keep the ISS at a full crew size of seven and allow the science output to stay at its current level. Seems simple, right?
But the return of Crew-2 to Earth has more variables than just keeping the ISS crew size stacked. The SpaceX Dragon is only designed to stay on the station for 210 days (about seven months). Crew-2 launched to the ISS on April 23, making that 194 days in orbit as of the date of publish of this article. While 16 days seems like a lot to get a launch off, NASA probably doesn’t want to tempt fate.
Possible tight payload or weather timelines for Crew-2’s return
The weather for Crew-2’s splashdown is just as important as the weather for Crew-3’s launch. Safe conditions for crew recovery are needed at the designated landing zone before spacecraft deorbit. If there’s an opening before Crew-3’s launch, NASA may take it rather than risk poorer conditions post-launch.
Another idea could be the requirements of scientific experiments returning in Crew-2’s Dragon. Along with the astronauts, SpaceX brings scientific experiments back for their ground-based researchers. NASA astronauts conduct a lot of research for many different entities on the ISS, so any number of items could be time-based.
NASA confirmed to Space Explored that “an indirect handover would be in play with additional delay in [Crew-3’s] launch.” However, they did not confirm whether any outside factors are at play or if a departure could occur this week.
When will Crew-2 return?
Unknown. If Crew-2’s return would happen this week, NASA should have already released details. If Crew-3 delays continue, that would be when an indirect handover would come into play. However, there is still a chance NASA will delay Crew-2’s departure in favor of a direct handover, putting it sometime within the next two weeks.
I’m sure Crew-2’s Shane Kimbrough, Megan McArthur, Akihiko Hoshide, and Thomas Pesquet won’t complain about having more time in space. It’s a problem I wouldn’t mind having, either.