Watch live: the historic and risky spacewalk attempt of the Polaris Dawn mission

Their week-long mission, called Polaris Dawn, is completely private with no NASA involvement, but it’s not a billionaire trip. This spacewalk is a critical test of the technical skills that SpaceX will need to achieve Elon Musk’s ultimate goal of building a city on Mars.

It’s also a risky feat for all four members of the Polaris Dawn crew: Jared Isaacman, benefactor and billionaire mission commander; Anna Menon and Sarah Gillis, two SpaceX engineers; and Scott Poteet, a retired Air Force pilot who previously led strategy at Isaacman’s company Shift4.

Even though only two will perform the spacewalk, the entire crew will float in the vacuum of space, wearing new spacesuits that have not yet been tested in orbit. The stakes are high.

“I know they take safety very seriously,” said Leroy Chiao, a retired NASA astronaut who spent more than 36 hours on spacewalks and consulted for SpaceX on its Time Safety Advisory Committee for 12 years, he told Business Insider in an email.

He added that SpaceX knows any accident would have a “severe impact” on commercial human spaceflight, “if not kill it.”

The Polaris program plans to broadcast the spacewalk live, most likely on the X. Business Insider will post details here as they become available.

According to SpaceX, the spacewalk will begin at 2:23 a.m. ET on Thursday. If you’re on the West Coast, it’s Wednesday at 11:23 p.m. SpaceX says there is also a backup opportunity on Friday.

“I will be watching with great interest,” Chiao said.

The Polaris Dawn spacewalk plan

The spacewalk procedure begins 48 hours before opening Crew Dragon’s hatch with a “pre-breather.”

The two-day process is supposed to slowly depressurize the spacecraft’s cabin and eventually put the crew on 100 percent oxygen. This helps to clear nitrogen from their blood and prevent a dangerous condition called “codes”.

This procedure is similar to the one astronauts on the International Space Station use before their spacewalks, although their pre-breaths last only a few hours because they do so in the confines of a small, enclosed space. Crew Dragon it has no airlock, so the crew must balance the pressure in the entire cabin with the pressure in their spacesuits and give everyone’s bodies a chance to adjust. Hence a longer pre-breath of 48 hours.

After the pre-breather, the Polaris crew should don their spacesuits—the first SpaceX ever designed for spacewalks. Each space suit will be connected to the spacecraft by an umbilical cord that will provide the astronauts with what they need to survive, such as power and air.

When the moment finally comes, the crew plans to open the hatch of the spacecraft. Since there is no airlock, this will expose the entire cabin of the vehicle and its crew to the vacuum of space.

“You’re taking a lot of risk at that point,” Isaacman said in an Aug. 19 briefing.

“You give up all the safety of your vehicle,” he added.

Then, if all goes according to plan, Isaacman and Gillis will leave the spacecraft to conduct tests on their spacesuits, but will always maintain contact with one of the many railings added to the exterior of the spacecraft for this mission. The other two – Menon and Poteet – will stay inside providing support.

The risks and stakes are high

The Polaris Dawn spacewalk plan – no sax, fully open space vehicle – is not entirely unprecedented. NASA’s Gemini and Apollo programs did the same.

Abhi Tripathi, former Dragon mission director at SpaceX who now leads mission operations at UC Berkeley’s Space Science Laboratory, told BI that the spacecraft was designed “from the ground up” to withstand unplanned depressurization events.

Tripathi added that he sees “no particular risk” with the spacewalk. In fact, he admitted to feeling a bit of “FOMO and jealousy” seeing his former colleagues Menon and Gillis go into space.

In addition, SpaceX spent two and a half years upgrading the Crew Dragon, testing it and running simulations with the four crew members to prepare for this spacewalk.

Chiao also expressed confidence that the company had “thoroughly reviewed” its flight plans.

But trying something new in space is risky. And there are many new features in this plan: a 48-hour pre-breathing protocol, the spacesuits, the fact that a Crew Dragon spacewalk has never happened before, and the fact that all crew members will be new to spacewalking.

Isaacman previously flew into space in 2021 on another Crew Dragon flight he commanded. Poteet was the mission director for that flight, called Inspiration4. Menon and Gillis have provided ground support for several SpaceX missions. None of them had ever been in the real vacuum of space before.

“They’re going to test a new suit with people who have never done this before,” Chiao said.

He added that depressurizing the entire cabin also adds risks to the two people who remain inside. They will also wear spacesuits, but it will still be a more precarious situation than sitting in a sealed, pressurized, environmentally controlled spaceship.

As with any mission or spacewalk, there is a risk that any of the millions of pieces of space debris orbiting Earth could impact the spacecraft and endanger its crew.

Tripathi previously worked in flight reliability at SpaceX, a division that is now led by Bill Gerstenmaier, who previously spent four decades overseeing various human spaceflight programs at NASA.

“I feel very comfortable that there is perhaps no better team in the world from a safety perspective than the people who are trying to make sure that every I is dotted and T is crossed at SpaceX,” Tripathi said.