In a somewhat cryptic tweet posted late last week, Elon Musk’s space faring company SpaceX announced that they had signed up their first passenger for a flight around the moon. The passenger’s identity was not revealed in the Tweet, though subsequent tweets posted by Musk himself suggest that their first customer may be from Japan.

The BFR, which was originally dubbed the “Big F*ckin Rocket” within SpaceX before being rebranded to “Big Falcon Rocket” for obvious publicity reasons. The platform promises to dwarf the Falcon Heavy, which is the most powerful rocket platform in use anywhere on the planet today (and another rocket in the SpaceX stable) by combining the force of 31 advanced Raptor engines. The Falcon Heavy is equipped with 27 older Merlin rocket engines, which altogether produce a maximum thrust of some 205,000 pounds of thrust each. The BFR may only boast four more engines than the Falcon Heavy, but each Raptor produces more than twice the thrust of a Merlin. At a maximum output of 430,000 pounds each, the BFR’s 31 engines will produce a whopping 13,330,000 pounds of thrust as it reaches the upper atmosphere, as compared to the Falcon Heavy’s total of just shy of 5.5 million pounds.

Despite offering little information thus far, the announcement actually offers some important insight into timelines and SpaceX’s manned space mission development. Originally, SpaceX had intended to send two human passengers on a trip around the moon using their Dragon crew capsule and the Falcon Heavy sometime this year, while they continued to develop the BFR with an eye toward Mars. SpaceX recently acknowledged that the Dragon capsule wouldn’t be ready for manned flights until April of next year. The announcement that the first moon flight will actually be aboard the forthcoming BFR rather than on the Falcon Heavy would seem to indicate plans to push their moon mission back even further.

How far will switching the BFR push their trip to the moon back? It’s hard to say — the BFR is little more than a paper rocket at this point, meaning that while there are plenty of specs to work with, the platform itself doesn’t exist yet. A great deal of development is yet to be completed, followed by a series of tests intended to ensure the BFR is safe for manned flight. Theoretically, that could all take years — but SpaceX’s decision to start selling tickets so soon might indicate that development is further along that it would seem.

Once completed, the BFR will measure some 30 feet wide, nearly three times that of their workhorse Falcon 9 rockets. It is expected to be fully reusable, standing at 348 feet tall with a crew compartment that encompasses 157.5 of those feet. That massive crew compartment is supposed to house 40 cabins capable of transporting as many as 100 passengers on a trip to Mars, making it the largest and most robust space craft ever built… once it actually has been built, that is.

Current predictions place the BFR’s first crewed flight at somewhere in 2024.