By Micah Maidenberg

Private-citizen astronauts traveling with SpaceX are poised to attempt the first commercial spacewalk, an operation that would push new boundaries at the Elon Musk-led company.

SpaceX aims to conduct the spacewalk, a centerpiece on the privately funded Polaris Dawn spaceflight, Thursday at 2:23 a.m. ET. The astronauts are set to test SpaceX-developed spacesuits, which the company envisions eventually being used on Mars.

Extravehicular activity, as spacewalks are called, is a fairly common part of orbital operations, like doing maintenance on the International Space Station. To date, spacewalks have only been conducted by government astronauts working on missions set up by national space agencies.

They are risky. Astronauts must maneuver through space with nothing between them and the vacuum of space but their spacesuits. The Polaris Dawn astronauts will be using SpaceX-designed and manufactured suits that are untested in orbit.

Jared Isaacman, a technology billionaire who is funding the flight, and Sarah Gillis, a SpaceX operations engineer, plan to exit from the vehicle for the walk, spending around 15 to 20 minutes outside. Both are set to stay connected by their hands or feet, as well as tethers, to the Crew Dragon spacecraft that is transporting them.

Scott Poteet, a retired Air Force pilot, and Anna Menon, a space operations engineer at SpaceX, are also on the flight. Isaacman paid for a separate SpaceX flight about three years ago.

The Polaris Dawn mission launched early Tuesday on a SpaceX rocket from Florida, and crew members began preparing for the spacewalk shortly after liftoff. Pressure levels inside the vehicle were slowly lowered as oxygen levels increased, helping get nitrogen out of the crew's bloodstreams and reduce decompression sickness.

On Tuesday, SpaceX said its Crew Dragon vehicle reached a distance of 870 miles above Earth, meaning the Polaris Dawn crew members were more than three times higher than the International Space Station -- the highest altitude humans have reached in space since NASA's Apollo program decades ago.

Both the private astronauts and their vehicle have undergone intensive testing over the past couple of years, according to SpaceX and members of the Polaris Dawn team. That has ranged from skydiving and entering a vacuum chamber to developing backup plans for the operation.

"In the event the hatch fails to close, they can manually close the hatch," Arthur Barriault, a space operations engineer at SpaceX, said in a company video. "We had them do that in a sideways suspension system, so gravity isn't helping them close or helping them open that hatch mechanism."

In addition to testing the spacesuits, the operation seeks to break new ground with Crew Dragon, SpaceX's low-Earth-orbit vehicle.

Because the craft has no airlock, all four crew members will don their suits before the vehicle is "vented," removing its pressure before the spacewalk and leaving its systems exposed to the vacuum of space. Crew Dragon has never been vented down in orbit.

SpaceX has said the spacewalk could be rescheduled for Friday morning if needed. The Polaris Dawn astronauts plan other tasks during their time on orbit, including scientific research and testing SpaceX's Starlink satellite network.

Write to Micah Maidenberg at micah.maidenberg@wsj.com

(END) Dow Jones Newswires

September 11, 2024 13:53 ET (17:53 GMT)

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