NASA and SpaceX are closer than ever to a moment both have been preparing for since the beginning of the Commercial Crew program in 2010. SpaceX’s Falcon 9 and Crew Dragon spacecraft are now set to fly with NASA astronauts Doug Hurley and Bob Behnken onboard, making a trip to the International Space Station, and both the agency and SpaceX announced that they have officially passed the final flight readiness review, meaning everything is now a ‘go’ for launch, TechCrunch reports.

According to NASA Commercial Crew Program manager Kathy Leuders during a press conference on Monday, May 25, everything went well with all pre-launch flight checks thus far, including a full-length static test fire of the Falcon 9’s engines, and a dress rehearsal of all launch preparation including strapping Hurley and Behnken into the rocket.

The only remaining major hurdle for SpaceX and NASA now is the weather, which is currently only looking around 40% favorable for a launch attempt on schedule for Wednesday, May 27 at 4:33 PM EDT, though during the press conference officials noted it is actually trending upwards.

SpaceX and NASA will be paying close attention to the weather until Wednesday, and since this is a highly sensitive mission with actual astronauts on board the spacecraft, they’ll err on the side of caution for scrubbing the launch if weather isn’t looking good. That said, they do have a backup opportunity of May 30 in case they need to make use of that, as well as another window on May 31.