A helium leak on the launch pad has forced SpaceX to hold off an overnight launch attempt of the Polaris Dawn mission with billionaire Jared Isaacman and three crewmates for at least one day.

“Teams are taking a closer look at a ground-side helium leak on the Quick Disconnect umbilical,” SpaceX posted on X late Monday. “Falcon and Dragon remain healthy and the crew continues to be ready for their multi-day mission to low-Earth orbit.”

The planned early Tuesday liftoff now shifts to early Wednesday. A Falcon 9 carrying the Crew Dragon Resilience and its four crew is targeting a 3:38 a.m, liftoff from KSC’s Launch Pad 39-A with backup options at 5:23 a.m. and 7:09 a.m. More backup options during the same times are available Thursday morning.

When it does launch, the first-stage booster, which is making its fourth flight, will aim for a recovery landing downrange in the Atlantic on the droneship A Shortfall of Gravitas.

The Crew Dragon Resilience is flying for the third time having debuted on the Crew-1 mission in 2020 and also having flown the Inspiration4 mission in 2021.

That second flight was Isaacman’s first trip to space, a three-day orbital mission that was the first ever all-commercial spaceflight that raised more than $250 million for St. Jude Children’s Research Hospital.

In 2022, Isaacman announced the Polaris Program in partnership with SpaceX with up to three missions with Polaris Dawn as the first. The final mission would be the first crewed flight of the in-development Starship and Super Heavy.

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But first up, Isaacman will be flying with one of his pilot buddies, former Air Force pilot Scott Poteet, and two SpaceX employees, Sarah Gillis and Anna Menon.

The highlight of the trip is what would be the first commercial spacewalk, targeting day three of the five-day orbital flight.

Isaacman and Gillis will venture outside the spacecraft that will open its hatch and vent the entire atmosphere out, meaning all four crew members will be wearing the new extravehicular activity (EVA) spacesuits that SpaceX developed in the last 2 1/2 years, and all breathing 100% oxygen.

Isaacman and Gillis will be connected to a 12-foot-long tether as they each spend about 15-20 minutes outside Resilience.

The flight also will take the spacecraft to a record 870-mile orbital altitude, test out a new Starlink communication experiment and tackle 40 more science and research efforts.