SpaceX’s Polaris Dawn crew will attempt the most dangerous spacewalk ever

SpaceX is preparing to conduct the first-ever private spacewalk. Until now, only government-trained astronauts have been able to leave a spacecraft and venture into space. But the Polaris Dawn mission, scheduled to launch after August 30, will change that and likely be the most dangerous private space mission in history.

The main risk is that Crew Dragon, which will carry the four astronauts into orbit, doesn’t have an airlock. When they perform a spacewalk, or extravehicular activity (EVA), on the International Space Station, they don their spacesuits and enter a sealed room. Before venturing into space, the air in that room is sucked out, and the rest of the station is kept sealed and filled with air.

Polaris Dawn’s crew is expected to spend up to five days in orbit. On the third day, the entire spacecraft will depressurize for about two hours, requiring even the two crew members who won’t leave the capsule to wear special spacewalk suits. It’s not an entirely new procedure — many of NASA’s Gemini and Apollo spacecraft from the 1960s and ’70s didn’t have airlocks — but it is far riskier than a spacewalk, in which astronauts can retreat to the relative safety of an airlock if something goes wrong.

“You’re throwing away all of the safety of the spacecraft, right? And the suit becomes the spacecraft,” mission commander Jared Isaacman said at a press conference on August 19. Isaacman is SpaceX’s head of the Polaris program and the project’s billionaire funder.

Another source of risk is the brand new spacesuits themselves. Though they undergo extensive testing in a vacuum chamber, any new type of gear tends to pose more risk than gear that has already been abused in space. There are other dangers, too: The flight will travel farther from Earth than humans have gone since the end of the Apollo program in 1972, and they will have to deal with radiation and possibly micrometeorites.

Isaacman is the only one of the four crew members who has been in space: the other three are a retired test pilot, SpaceX’s chief astronaut trainer, and one of SpaceX’s chief space operations engineers. All three have worked in mission control on previous flights and have been training intensively for two years for this mission.

“They’re not government astronauts, but they’re not space tourists either, and they’re professionals,” said Laura Forczyk, an independent space industry consultant. “I can’t think of four non-government astronauts better suited for this mission.”

So the Polaris Dawn mission carries many inherent risks, but those risks should be greatly mitigated by the extreme level of preparation that SpaceX and its astronauts will undertake. While there is no space mission without risk, much less a risk-free spacewalk, this will be a crucial test of Crew Dragon and SpaceX’s new spacewalk suit, and the astronauts will also be conducting nearly 40 science experiments while in space.

“All spacewalks are dangerous, but I wouldn’t say this one is particularly dangerous,” Forczyk said. “They’ve looked at every scenario, they have backups and redundancies for every scenario, and they’re very well prepared.”