SpaceX is preparing to launch its next private mission by the end of the month, featuring the first attempt to have the astronauts step out into space.

The Polaris Dawn mission — the first of three flights billionaire and Shift4 founder Jared Isaacman purchased from SpaceX in 2022 for his human spaceflight effort known as the Polaris Program — is set to launch from Florida in the early hours of Aug. 26.

“We don’t get the freedom of any time of day to launch but I think it’ll work out to [be] pretty close to dawn, which is very appropriate given the mission,” Isaacman told CNBC’s Investing in Space during an interview last month.

Isaacman will be commanding the mission, as he did while leading the historic Inspiration4 flight in 2021. He’s once again leading a crew of four, with longtime colleague Scott Poteet joining him as the pilot and Anna Menon and Sarah Gillis, a pair of SpaceX employees, serving as the flight’s medical officer and mission specialist, respectively.

The multi-day trip isn’t headed to a destination, but instead will be a free-flying mission tracing orbits that the crew hopes will go far from Earth.

“We’re going to a very high altitude that humans haven’t gone to in 50-plus years,” Isaacman said.

But the centerpiece of Polaris Dawn is the planned spacewalk.

Extravehicular activities, or EVAs, have been a regular part of NASA’s astronaut missions for years, such as when the agency needs maintenance done outside the International Space Station. But no private venture has attempted an EVA before.

Isaacman said he understands that going for a spacewalk means he and his crew will be “surrounded by death,” a moment for which they’ve been training extensively.

“The only thing that comes close to that is the vacuum chamber, and that’s where you’re pretty much feeling as close as it’s like to be in the vacuum conditions or space. … That definitely gives you the actual sensations of the pressure changes and the temperature changes, as well as just the psychological stressors of being in a very harsh environment,” Isaacman said.

The spacecraft will also take early passes through the high radiation zone known as the South Atlantic Anomaly.

“You ideally want to take that at the lowest altitude as you can because even down at 200 kilometers, the radiation level there is substantially higher … Our two or three passes at high altitude through the South Atlantic Anomaly will be almost the entirety of the radiation load on the mission and like an equivalency of three months on the International Space Station,” Isaacman said.

Day two will focus on some of the science and research that Polaris Dawn plans to accomplish — which will total about 40 experiments. The crew will also prep for the spacewalk, testing out the EVA suits.

“So we can make sure that … there’s nothing unexpected in microgravity versus what we were able to test on Earth,” Isaacman said.

Day three is the big one: The EVA.

Read Isaacman’s Q&A with CNBC’s Investing in Space newsletter here.