SpaceX and Elon Musk announced on Monday thaton the BFR (Big Falcon Rocket) spaceship for a flight around the moon planned for 2023.
Kelly tweeted his good wishes to Maezawa on Tuesday, "Good luck on your trip and if you need someone with a little experience to go with you, my schedule is wide open in 2023."
The lunar mission could take four or five days, which would feel like a hot minute to Kelly, who has logged 520 days in space, including a yearlong mission on the International Space Station. Kelly retired from NASA in 2016.
Maezawa retweeted Kelly's message, but didn't actually chime in to say if he would consider the astronaut's offer.
The Japanese billionaire entrepreneur plans to take a group of artists with him on the moon trip as a part of a project called #dearMoon. Maezawa, an avid art collector, hopes the experience will inspire the artists to create new works based on their adventure.