SpaceX on Monday said that it has been approached by two private citizens interested in taking a trip around the moon next year.

The individuals, who haven’t yet been named, have already put down a “significant” deposit for the mission. The Verge notes that while SpaceX CEO Elon Musk declined to say exactly how much the trip would cost, he said it was comparable to the cost of a crewed mission to the International Space Station.

For reference, a ticket on the Russian Soyuz capsule costs NASA around $80 million.

SpaceX said they expect to conduct health and fitness tests and begin initial training later this year.

When the time comes, the individuals will blast off into outer space abroad a Crew Dragon capsule from Kennedy Space Center’s historic Pad 39A near Cape Canaveral using SpaceX’s Falcon Heavy rocket. That’s the same launch pad used by the Apollo program for its lunar missions.

The private citizens won’t be landing on the moon but will instead circumnavigate it, traveling faster and further into the solar system than any humans before them. Assuming the timeline sticks, it’ll all take place over the course of one week late next year. The total distance traveled will be between 300,000 to 400,000 miles.

SpaceX says others have also expressed strong interest in similar missions. If successful and sustainable, private flights like this could serve as a significant driver of revenue for SpaceX to the tune of up to 20 percent of annual revenue.

Image courtesy Mario Anzuoni, Reuters