Very early on Tuesday morning, Jared Isaacman, a billionaire entrepreneur, is scheduled to launch to space for a second time. The five-day mission, known as Polaris Dawn, is a collaboration between Mr. Isaacman and SpaceX, the rocket company led by Elon Musk.

It will mark some milestones for private spaceflight — the first spacewalk conducted by nonprofessional astronauts, and the farthest journey from Earth by anyone since NASA’s moon landings more than 50 years ago.

How do I watch the Polaris Dawn launch?

It is scheduled for 3:38 a.m. Eastern time on Tuesday from NASA’s Kennedy Space Center in Florida. If bad weather or technical glitches arise, the launch window extends until 7:38 a.m.

SpaceX is providing live coverage of the launch on its website and its X account.

Why has the flight been delayed?

The launch was scheduled for Aug. 28, but was called off because of a helium leak. After that, unsettled weather around Florida has proved troublesome — not so much for the launch, but for the splashdown on the sixth day.

The Polaris Dawn mission carries limited amounts of air, food, and other supplies. “Unlike an I.S.S. mission, we don’t have the option to delay long on orbit, so we must ensure the forecast is as favorable as possible before we launch,” Mr. Isaacman explained on X.

The weather outlook for the return to Earth appears better, but the odds that Polaris Dawn will get off the ground are still iffy. There is only a 40 percent chance of favorable weather for liftoff. Weather is similarly problematic for Wednesday and improves slightly on Thursday.