SpaceX will launch an American billionaire aerospace hobbyist and three experienced astronauts on the first private commercial spacewalk on Wednesday.
Jared Isaacman will be carried out to a record altitude for an Earth-orbit mission of 870 miles, for an undisclosed price.
That distance is a third of the way to the moon and 600 miles away from Earth.
"This will be the first spacewalk by a commercial company and the furthest from Earth anyone has travelled in over half a century!" SpaceX founder Elon Musk said in a tweet.
Isaacman, who made his fortune from founding the payments firm Shift4 and took up flying jets as a hobby, will board the Crew Dragon capsule Resilience, atop a Falcon 9 rocket for the mission, which is named Polaris Dawn.
He and three others will travel on a five-day flight, the first of three Polaris program spaceflights, blasting off at around 3:38 am Eastern time on 28 August, with two other launch opportunities during a four-hour launch window.
Alongside Isaacman, who has been given the title of mission commander, will be retired US Air Force flyer Scott Poteet as pilot, Sarah Gillis, SpaceX lead space operations engineer for astronaut training, and Anna Menon, SpaceX lead operations engineer for crew operations development.
As well as trying to reach the highest Earth orbit ever flown since the Apollo moon landing program and participate in the first-ever commercial spacewalk, the astronauts will aim to carry out 36 research studies and experiments from 31 universities and other research partners and to test Starlink laser-based communications in space.
The spacecraft being used for this mission previously flew astronauts to and from the International Space Station as well as the Isaacson-funded first all-civilian mission to orbit, Inspiration4, in 2021.