We'll have to wait at least another day to see SpaceX's historic Polaris Dawn astronaut mission lift off.

Polaris Dawn, which will conduct the first-ever private spacewalk, had been scheduled to launch early Tuesday morning (Aug. 27) from NASA's Kennedy Space Center in Florida. But a helium leak has forced a delay of at least 24 hours.

"Teams are taking a closer look at a ground-side helium leak on the Quick Disconnect umbilical. Falcon and Dragon remain healthy and the crew continues to be ready for their multi-day mission to low Earth orbit. Next launch opportunity is no earlier than Wednesday, August 28," SpaceX announced in an X post on Monday evening (Aug. 26). 

The launch, atop a Falcon 9 rocket, is now targeted for 3:38 a.m. EDT (0738 GMT) on Wednesday, though there are two backup opportunities on that day as well — 5:23 a.m. EDT (0923 GMT) and 7:09 a.m. EDT (1109 GMT). You can watch the action via a SpaceX webcast, which will begin at around midnight EDT (0400 GMT).