SpaceX has announced plans to fly two private citizens around the Moon next year, in the first manned US mission since the 1970s.
The tourists, who have paid a "significant deposit" for the week-long trip, will travel using a spaceship being developed for NASA astronauts - as well as a heavy-lift rocket that is yet to be flown.
SpaceX chief executive Elon Musk said he hopes the privately funded flight - the first ever to travel beyond the International Space Station - will happen in late 2018.
Mr Musk did not reveal who his two customers are, nor how much they paid, but the entrepreneur told reporters they are not from Hollywood.
The pair's long lunar loop could seen them travel hundreds of thousands of miles - as a one-way trip to the Moon covers 384,400 km alone.
When asked whether his customers are aware of the dangers of space travel, Mr Musk said: "They're certainly not naive, and we'll do everything we can to minimize that risk, but it's not zero. But they're coming into this with their eyes open."
The billionaire described the plans as "incredibly exciting" - and said SpaceX plans to do more than one mission in the not-too-distant future.
"Like the Apollo astronauts before them, these individuals will travel into space carrying the hopes and dreams of all humankind, driven by the universal human spirit of exploration," he added.
"This presents an opportunity for humans to return to deep space for the first time in 45 years and they will travel faster and further into the solar system than any before them."
SpaceX says it is on track to send astronauts to the ISS on NASA's behalf in the middle of 2018, with the private Moon mission following about six months later.
Although the two lucky passengers are going to fly to the Moon, they will not land on its surface.
The pair are now going to embark on a series of health tests and training for their autonomous flight.
An unmanned test flight of the Crew Dragon capsule they will be travelling on is scheduled for later this year.
The design is similar to the spacecraft currently used to send cargo to the ISS, with upgrades to make it suitable for human transport.
It will launch on top of SpaceX's Heavy Falcon rocket, which is scheduled for its first test flight later this summer.
The company has enjoyed some considerable successes during its foray into space travel - as well as some failures.
Last September, a Falcon 9 rocket exploded on a launchpad in Florida - destroying more than $200m (€188m) worth of equipment.
