SpaceX today announced plans to send two private citizens on a trip around the Moon next year. The launch will use the company’s Falcon Heavy rocket and Crew Dragon, neither of which has flown yet.

SpaceX is under contract to NASA to develop Crew Dragon as a “commercial crew” vehicle to take astronauts to and from the International Space Station (ISS). Today’s announcement stated that the private citizen trip to the Moon will take place after operational commercial crew flights have begun. SpaceX insists that its Crew Dragon, launched by the Falcon 9 rocket, will be operational in 2018, although the Government Accountability Office (GAO) expressed doubt that it would fly before 2019 in a report released earlier this month. In response, SpaceX President Gwynne Shotwell said “the [heck] we won’t fly before 2019.”

The company said again today that it plans to launch an unoccupied test version of Crew Dragon later this year and the first flight with a crew in the second quarter of 2018. Operational flights would ensue thereafter. SpaceX already launches a cargo version of Dragon to ISS; one is docked there right now. It is not outfitted for crews, however.

The Falcon Heavy rocket has been under development for several years. The date for its first launch has slipped repeatedly, most recently from November 2016 to sometime this summer. SpaceX says that it is two-thirds the size of the Saturn V rocket that sent Apollo astronauts to the Moon.

The two private citizens were not identified, but SpaceX says they have already paid a “significant deposit.” The price was not revealed.

The announcement comes just three days after a NASA media teleconference where two NASA officials discussed an ongoing internal study to determine the feasibility of putting a crew on the first launch of NASA’s new rocket — the Space Launch System (SLS). Under NASA’s current plan, the first SLS, Exploration Mission-1 (EM-1), will be launched with an unoccupied Orion spacecraft. It is scheduled for launch at the end of 2018, although that date appears likely to slip into 2019. A crew would not fly on SLS/Orion until the second launch, EM-2, currently targeted for August 2021. NASA Acting Administrator Robert Lightfoot has asked for a study to determine the safety, technical and cost implications of changing that plan and putting astronauts on EM-1 for an 8-9 day mission to lunar orbit. The study should be done in about a month.

The initial version of SLS will be able to launch 70 metric tons (MT) into low Earth orbit (LEO), compared to 54 MT for Falcon Heavy. Later versions of SLS will be capable of placing 105 MT and 130 MT into LEO.

Some view SpaceX’s announcement as a challenge to NASA — a new space race. The two did not paint that picture, however. SpaceX enthused about NASA’s role in getting the company to where it is today: “Most importantly, we would like to thank NASA, without whom this would not be possible.” Musk frequently praises NASA for rescuing his fledgling company a decade ago after it suffered three Falcon 1 launch failures in a row, but NASA selected it for the COTS commercial cargo development program anyway. SpaceX just launched its 10th commercial cargo mission for NASA on February 19. NASA selected SpaceX (and Boeing) for the final phase of the commercial crew program in 2014.

For its part, NASA said in a press release that it “commends its industry partners for reaching higher” and will continue to work with SpaceX “to ensure it safely meets its contractual obligations” on commercial crew and commercial cargo.

In an interview, Commercial Spaceflight Federation (CSF) President Eric Stallmer called the announcement “exciting” and, if it is a race, it is “in the best spirit possible.” If it motivates NASA to move more quickly, “that’s a win for everyone.” CSF is working with the international standards organization ASTM International on developing voluntary industry standards for commercial human spaceflight. The FAA’s Office of Commercial Space Transportation has limited regulatory authority now and is prohibited from developing new regulations until 2023, but industry could set its own standards. By law, companies must only provide informed consent to passengers who want to fly into space, warning them of the risks and letting them make their own decisions on whether to accept them.