SpaceX tweeted tonight that on Monday, September 17, it will announce the name of the first private passenger who will fly around the Moon on the company’s Big Falcon Rocket (BFR). A time frame for the flight was not mentioned. Last year SpaceX founder and CEO Elon Musk announced that he would fly two people around the Moon in 2018 using the Falcon Heavy (FH) rocket, but revealed at the time of the FH’s first flight that he abandoned those plans and would wait for the BFR.

A second tweet reminded everyone that only 24 humans have flown around the Moon so far and none since 1972.

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. pic.twitter.com/64z4rygYhk — SpaceX (@SpaceX) September 14, 2018

Only 24 humans have been to the Moon in history. No one has visited since the last Apollo mission in 1972. https://t.co/gtC39uBC7z — SpaceX (@SpaceX) September 14, 2018

The BFR is still in development. It is described as a Saturn V-class rocket that will be used to send humans to Mars. The second stage — Big Falcon Spaceship (BFS) — would carry the crew. Conceptual illustrations like the one in the tweet above continue to evolve.

Musk said in February that he expects the first BFR flight to Earth orbit to take place in three to four years, followed by trips to the Moon and eventually Mars.

In February 2017, Musk surprised the world by announcing that he would fly two people around the Moon in 2018 using the Falcon Heavy (FH) and Crew Dragon. The latter is being developed as part of NASA’s commercial crew program and has not flown yet. The FH made its first flight on February 6, 2018, but Musk revealed at the time said he has “tabled” plans for human-rating that rocket and will wait for the more capable BFR.

SpaceX’s website says that the announcement on Monday will be at 6:00 pm Pacific Time (9:00 pm Eastern). A link to a webcast is posted there already.