After walking back plans to take a pair of passengers on a trip around the Moon before the end of 2018, SpaceX now says it has a single passenger ready and waiting to hop aboard its huge BFR, or Big Falcon Rocket, for a luna expedition.

Elon Musk's rocket-building company initially announced in early 2017 that the flight with two passengers would take place before the end of 2018, but this was put into doubt a year later when Musk said he was unsure about which model of rocket to use.

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Now though, the company says it will reveal details about the flight and the passenger on Monday, September 17, during a live video stream.

Currently in development and yet to fly, the BFR is what SpaceX intends to use to take humans into deep space. The ultimate goal is to take humans and cargo to the Moon, and then eventually to Mars, where Musk plans to establish a colony and turn humans into a multi-planetary species within his lifetime.

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It has also been suggested by Musk and SpaceX that the BFR could be used to launch satellites, and even provide a form of point-to-point travel on Earth, taking passengers almost anywhere on the planet within an hour. Musk has said a trip from New York to London would take just 29 minutes.

SpaceX said in a tweet on September 14: "SpaceX has signed the world's first private passenger to fly around the Moon aboard our BFR launch vehicle - an important step toward enabling access for everyday people who dream of traveling to space. Find out who's flying and why on Monday, September 17."

It isn't known at this stage if the passenger is one of the original pair, or someone new. When asked on Twitter if he would be the passenger, Musk replied with an emoji of the flag of Japan. This prompted his followers to begin guessing on who the individual might be - including a suggestion of Satoshi Nakamoto, the pseudonymous creator of bitcoin, which naturally led to chat of Musk being Nakamoto.

Powered by 31 Raptor engines, the BFR is capable of carrying 150 tons of payload into low Earth orbit.

Details released by SpaceX about the previously planned trip with two space tourists said how the trip would take about a week. It would see the rocket pass closely by the Moon, head further into space, then loop back around toward Earth. This new single-passenger trip will likely follow a similar route.

Those passengers, who were said to be "very serious" about the trip when approaching SpaceX with a "significant deposit", were not named.

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