Isaacman, 41, and Gillis, 30, rose from the hatch door into space to test various body movements in the suit, voicing feedback to ground control to inform future design iterations. Their posture appeared stiff. They were able to move their arms at the elbow and shoulder but less so at the waist, back and neck.

The mission also verified procedures for the capsule, among other things, in a mission meant to test the limits of what private companies can do in orbit.

Ground teams at SpaceX’s Hawthorne, California, headquarters watched as the capsule’s hatch door sealed shut, and carried out leak checks as the astronauts returned to their cabin seats.

The first US spacewalk in 1965, aboard a Gemini capsule, used a similar procedure: the capsule was depressurised, the hatch opened, and a spacesuited astronaut ventured outside on a tether.

NASA Administrator Bill Nelson, whose agency helped fund Crew Dragon’s development beginning roughly a decade ago, lauded the latest accomplishment.

“Today’s success represents a giant leap forward for the commercial space industry and @NASA’s long-term goal to build a vibrant US space economy,” Nelson wrote on social media.

Isaacman has declined to say how much he is paying, but his missions are likely to cost hundreds of millions of dollars, based on Crew Dragon’s price of roughly $US55 million ($82 million) a seat for other flights.

Gillis started at SpaceX as an intern in 2015. Poteet, 50, is a retired US Air Force lieutenant colonel. Menon, 38, is a SpaceX engineer.

Loading

Throughout Wednesday, the craft circled Earth at least six times in an oval-shaped orbit as shallow as 190 km and stretching out as far as 1400 km, the farthest in space that humans have travelled since the last US Apollo mission to the moon in 1972.

Only government astronauts with several years of training have conducted spacewalks in the past. There have been roughly 270 on the International Space Station (ISS) since it was set up in 2000, and 16 by Chinese astronauts on China’s Tiangong space station.

Reuters

Get a note directly from our foreign correspondents on what’s making headlines around the world. Sign up for our weekly What in the World newsletter.