Jared Isaacman, CEO of Shift4 integrated payment processing solutions, participated in the first private spacewalk by a group of astronauts who left a SpaceX capsule after a delay of a few hours, testing a new line of spacesuits in the company's riskiest mission yet.

Along with the billionaire entrepreneur is a retired military fighter pilot and two SpaceX employees. The four have been orbiting Earth aboard Crew Dragon since Tuesday's pre-dawn launch from Florida of the Polaris Dawn mission.

This is a developing story. Check back here for updates. 

Reuters contributed to this report.