Japanese billionaire Yusaku Maezawa announced Thursday the postponement of his journey around the Moon on a SpaceX rocket, a voyage that boasts an artist-filled crew.

"We were planning for our lunar orbital mission 'dearMoon' to take place in 2023, but seems like it will take a little longer," Maezawa said.

"We're not sure when the flight will be," the entrepreneur said on X, formerly Twitter.

The crew on the mission announced in 2018 would be travelling on SpaceX's Starship rocket, which is still under development and will be the most powerful rocket ever built when complete.

The postponement was "due to the on-going development of Starship", according to a statement on dearMoon's website.

"The vehicle's first flight test in April 2023 provided numerous lessons learned that are directly contributing to upgrades being made to improve the probability of success on future Starship flights," the statement read.

Maezawa bought all the seats aboard the rocket and in 2021 created a competition in which artists could apply to join him.

From about one million applicants, Maezawa chose a multinational crew of eight: DJ and producer Steve Aoki, YouTuber Tim Dodd, artist Yemi AD, photographers Rhiannon Adam and Karim Iliya, filmmaker Brendan Hall, actor Dev Joshi, and K-pop musician TOP.

There were also two backup crew members: snowboarder Kaitlyn Farrington and dancer Miyu.

Their planned trip will last about six days and circumnavigate the Moon without landing, according to a mission profile graphic on the dearMoon website.

The Starship's second flight test "could launch as soon as mid-November, pending regulatory approval", according to the SpaceX website.

Maezawa, the founder of Japan's largest online fashion mall, flew to the International Space Station aboard a Russian Soyuz rocket in 2021.