SpaceX Prepares for Historic Private Spacewalk

SpaceX's attempt at the first ever private spacewalk next week will be a test of trailblazing equipment, including slim spacesuits and a cabin with no airlock, in one of the riskiest missions yet for Elon Musk's space company.

A billionaire entrepreneur, a retired military fighter pilot and two SpaceX employees are poised to launch aboard a modified Crew Dragon craft, before embarking on a 20-minute spacewalk 700 km into space two days later.

Until now, walking into the empty expanse of space has only been attempted by government astronauts on the International Space Station (ISS), 400 km above Earth.

SpaceX's five-day mission - dubbed Polaris Dawn - will swing in an oval-shaped orbit, passing as close to Earth as 190 km and as far as 1,400 km, the farthest any humans will have ventured since the end of the United States' Apollo moon program in 1972.

Crew members, including billionaire Jared Isaacman, will don SpaceX's new, slimline spacesuits, and the Crew Dragon vehicle will be modified so it can open its hatch door in the vacuum of space - an unusual process that removes the need for an airlock.

"They're pushing the envelope in multiple ways," retired NASA astronaut Garrett Reisman said in an interview. "They're also going to a much higher altitude, with a more severe radiation environment than we've been to since Apollo."

The mission has been bankrolled by Isaacman, the founder of electronic payment company Shift4. He has declined to say how much he has spent, but it is estimated to be over $100 million.

Joining him will be mission pilot Scott Poteet, a retired U.S. Air Force lieutenant colonel, and SpaceX employees Sarah Gillis and Anna Menon, both senior engineers at the company.

For SpaceX, which has pioneered cheap, reusable rockets and expensive private spaceflight, the mission is an opportunity to advance technologies that could be used on the moon and Mars.