The first fully private mission to the International Space Station is set to blast off Friday with a four-member crew from startup company Axiom Space.
The partnership has been hailed by NASA, which sees it as a key step in its goal to commercialize the region of space known as "low Earth orbit," leaving the agency to focus on more ambitious endeavors deeper into the cosmos.
Takeoff is set for 11:17 am (1517 GMT) from the Kennedy Space Center in Florida on a SpaceX rocket.
Commanding the Axiom-1 mission will be former NASA astronaut Michael Lopez-Alegria, a dual citizen of the United States and Spain.
He is joined by three paying crewmates: American real estate investor Larry Connor, Canadian businessman Mark Pathy, and Israeli former fighter pilot and entrepreneur Eytan Stibbe.
The widely reported price for tickets -- which includes eight days on the outpost -- is $55 million.
But unlike the recent, attention-grabbing suborbital flights carried out by Blue Origin and Virgin Galactic, Axiom says its mission shouldn't be considered tourism.
On board the ISS, which orbits 250 miles (400 kilometers) above sea level, the quartet will carry out scientific research projects, including on aging in space, experiments with stem cells, and a technology demonstration of a self-assembling spacecraft.
"The distinction is that our guys aren't going up there and floating around for eight days taking pictures and looking out of the cupola," Derek Hassmann, operations director of Axiom Space, told reporters at a pre-launch briefing.
"I mean we have a very intensive and research-oriented timeline plan for them."
In addition, crewmember Stibbe plans to carry out a tribute to his friend Ilan Ramon, Israel's first astronaut, who died in the 2003 Space Shuttle Columbia disaster when the spaceship disintegrated upon reentry.
Surviving pages from Ramon's space diary, as well as mementos from his children, will be brought to the station by Stibbe.
The Axiom crew will live and work alongside the station's regular crew: currently three Americans and a German on the US side, and three Russians on the Russian side.
The company has partnered for a total of four missions with SpaceX, and NASA has already approved in principle the second, Ax-2.
Axiom sees the voyages as the first steps of a grander goal: to build its own private space station. The first module is due to launch in September 2024, president and CEO Michael Suffredini said.
The plan is for it to initially be attached to the ISS, before eventually flying autonomously when the latter retires and is deorbited sometime after 2030.