SpaceX's second private flight has sent passengers, including Saudi Arabia's first female astronaut, rocketing towards the International Space Station.
The SpaceX Falcon rocket launched from NASA's Kennedy Space Centre on Sunday night, and the four passengers are expected to reach the space station in their capsule on Monday.
They will spend just over a week there before returning home with a splashdown just off the coast of Florida.
Saudi Arabia's first astronauts in decades are stem cell researcher Rayyanah Barnawi, and Royal Saudi Air Force fighter pilot Ali al Qarni.
"This is a dream come true for everyone," Ms Barnawi said before the flight.
"Just being able to understand that this is possible - if me and Ali can do it, then they can do it, too."
The journey was organised by Houston-based Axiom Space and the crew is led by Peggy Whitson, a former NASA astronaut who now works for the company.
Ms Whitson holds the US record for the most accumulated time in space - 665 days and counting.
Rounding out the crew is John Shoffner, a US businessman who owns a sports car racing team.
The company would not reveal how much the latest tickets cost, but previously cited per-seat prices of $55m (£44m).
NASA's latest price list shows per-person, per-day charges of $2,000 (£1,600) for food and up to $1,500 (£1,200) for sleeping bags and other gear.
The charge to get gear to the space station in advance is around $10,000 (£8,000) per pound, with the same fee for disposing of it afterwards. It costs the same again for the items to be handed back intact.
The guests will have access to most of the station as they conduct experiments, photograph Earth and chat with schoolchildren back home, demonstrating how kites fly in space when attached to a fan.