Crew of SpaceX's Polaris Dawn complete first commercial spacewalk

The crew of SpaceX's Polaris Dawn mission on Thursday carried out the first commercial spacewalk in human history.

Live images showed tech billionaire Jared Isaacman and SpaceX engineer Sarah Gillis emerging from the hatch of the Crew Dragon capsule in space suits around 740 kilometres above the Earth.

The extravehicular activity (EVA) came two days after Isaacman, Gillis and two further crew members lifted off from Cape Canaveral spaceport on the west coast of Florida.

The astronauts tested a new space suit, designed for use on potential missions to the moon and Mars.

Isaacman and Gillis were attached to the spacecraft at all times, with air supplied via a hose.

The EVAs were carried out after a delay, the reasons for which SpaceX has not yet revealed.

Former German astronaut Ulrich Walter said the spacewalk was a potentially dangerous manoeuvre, as astronauts at the International Space Station (ISS) usually have several weeks to acclimatize for an EVA.

However, Walter said the fact that none of the four members were conventionally trained government astronauts represents "a sign of progress in space travel."

The Polaris Dawn mission is, for Walter, less about scientific achievements, but more about demonstrating the possibilities of space tourism.

"It's about showing people that even people who are not experienced astronauts can fly wonderfully," he argued.