Billionaire Jared Isaacman, the mission's financial backer, and SpaceX employee Sarah Gillis ventured for about ten minutes outside the capsule early Thursday.

The other two passengers, SpaceX engineer Anna Menon and retired Air Force pilot Scott Poteet, remained in their seats but were exposed to the vacuum of space, as the capsule has no airlock.

Here is more information about the four history-making Americans:

- Jared Isaacman, billionaire -

The driving force behind the mission is Jared Isaacman, a billionaire who serves as mission commander.

The 41-year-old American from Pennsylvania is the CEO of the digital finance company Shift4 Payments, which he founded in his family's basement when he was only 16.

Isaacman is a seasoned pilot who is qualified to fly military aircraft and holds several world records.

He had previously gone into space in 2021 as part of another SpaceX mission he chartered, Inspiration4, which was the first orbital spacecraft to feature no professional astronauts.

His lifelong passion for space exploration aligns with SpaceX's stated goal of making humankind a "multi-planet species."

"Throughout Earth's history, there have been periods when humans, had we existed, would have been wiped out," Isaacman wrote on X in August. "If there's a technical path to ensuring humanity's survival...it seems irresponsible not to pursue it."

Isaacman is married with two daughters.

- SpaceX employees Sarah Gillis and Anna Menon -

For the first time, SpaceX has sent two of its own employees into space.

Sarah Gillis, 30, oversees astronaut training for SpaceX, and had trained Isaacman for his Inspiration4 mission.

Her husband also works for Elon Musk's company, having helped develop the propulsion system for the spacecraft used in Polaris Dawn.

Anna Menon, 38, worked for NASA before joining SpaceX, where she is a lead space operations engineer.

She wrote a children's book about space titled "Kisses from Space" that she will read an excerpt from during the mission. Proceeds from the book go to support a children's hospital.

Her husband Anil Menon was selected to be an astronaut by NASA in 2021, but unlike his spouse, he has yet to go to space.

On the first day of the Polaris Dawn mission, Gillis and Menon became the two women to have traveled the farthest from Earth, at an altitude of around 1,400 km (870 miles).

NASA did not permit women to be astronauts until years after its Apollo missions to the Moon.

- Pilot Scott Poteet -

The last Polaris Dawn participant is Scott Poteet, a US Air Force veteran who enjoys completing triathlons in his spare time.

Poteet flew combat aircraft for 20 years, including as part of the esteemed Thunderbirds air aerobatic patrol.

He serves as the mission's pilot, given his professional experience.

Poteet is also a close friend of Isaacman's, having worked for several of the billionaire's companies.