BILLIONAIRE Elon Musk plans to launch a “private passenger” on a space trip around the Moon.

The mission will be operated by Musk’s SpaceX rocket company, but there’s no telling who will actually be on board, The Sun reports.

SpaceX first announced its Moon mission back in February 2017, but details were light at the time.

The rocket firm originally planned to send two private citizens on a space trip around Earth’s closest neighbour, using the company’s Big Falcon Rocket.

However, it now seems that just one passenger will be on board.

In a tweet last night, SpaceX wrote: “SpaceX has signed the world’s first private passenger to fly around the Moon aboard our BFR launch vehicle.”

SpaceX added that it was “an important step toward enabling access for everyday people who dream of travelling to space.”

Importantly, SpaceX didn’t actually reveal who the passenger was.

Instead, Mr Musk’s firm promised to announce the identity of the soon-to-be-astronaut on Monday, September 17.

PayPal and Tesla founder Mr Musk is staying tight-lipped too, but offered a key hint.

Someone on Twitter said “Elon, it’s you, isn’t it?”, to which he replied with the Japanese flag emoji.

This likely means the person set to take part in the flight will be either Japanese, or living in Japan.

It’s also probable that the person will be very rich — building the rocket and launching it will likely cost billions.

There’s no word on whether the passenger will have to fund the trip themselves, or if SpaceX will be picking up some (or all) of the cost.

The mission is expected to use SpaceX’s upcoming Big Falcon Rocket system.

The 48-metre-tall spaceship sits atop a 58-metre booster rocket, and is expected to carry SpaceX’s manned missions to Mars — which Mr Musk says may begin as soon as next year.

Mr Musk’s lunar loop trip is a good opportunity to test the BFR before it takes aim at the red planet.

Sadly, we have no idea when the trip-around-the-Moon mission will take place.

Neil Armstrong became the first man on the moon on July 20, 1969, so perhaps the trip may be timed to coincide with the 50th anniversary of that historic feat next year.

This Moon trip will be a bit of much-needed positive publicity for controversial SpaceX boss Mr Musk.

Just last week, the billionaire was propositioned by a porn firm to star in a weed-themed adult movie.

It came just days after billionaire Mr Musk was filmed smoking weed live on camera.

The PayPal founder appeared on the Joe Rogan Experience podcast, puffing on a joint for all the world to see.

The billionaire is also facing three potential lawsuits in different countries after accusing a British diver of being a “paedo”.

Vernon Unsworth, who helped in the rescue of children from a Thailand cave earlier this year, was attacked by Mr Musk on Twitter.

Mr Musk dubbed Mr Unsworth a “paedo guy” without offering any proof, and doubled down on the accusation in several tweets sent later.

The Tesla boss did eventually apologise, but later queried why Mr Unsworth hadn’t actually sued him — hoping to cast doubt on the diver’s character.

Mr Unsworth is now reportedly preparing to sue Mr Musk — who has a net worth of $20.4 billion — for defamation in London, New York and Thailand.