On Monday, NASA Administrator Jim Bridenstine held a town hall for agency employees to begin talking about how they can return humans to the Moon by 2024. This was the goal set down by Vice President Mike Pence last week during a space policy speech in Huntsville, Alabama.

The discussion was short on details until Bridenstine was asked why an idea to use private rockets to launch the Orion spacecraft on an uncrewed test flight around the Moon was unworkable. The administrator replied that the agency had looked at a variety of options using United Launch Alliance's Delta IV Heavy rocket, SpaceX's Falcon Heavy rocket, or (perhaps most intriguingly) a combination of the two.

"By the way, I was for it, because the visuals would be beautiful," Bridenstine said. Unfortunately, none of these options really worked for a 2020 mission due to a variety of reasons. These included the availability of Delta IV Heavy rockets, launchpad issues, and Orion's lack of capability to dock autonomously with a rocket's upper stage in orbit.

Flying on the Falcon

However, Bridenstine then laid out one scenario that has huge implications, not for a 2020 launch, but one later on. Until now, it was thought that only NASA's Space Launch System could directly inject the Orion spacecraft into a lunar orbit, which made it the preferred option for getting astronauts to the Moon for any potential landing by 2024. However, Bridenstine said there was another option: a Falcon Heavy rocket with an Interim Cryogenic Propulsion Stage built by United Launch Alliance. "Talk about strange bedfellows," he mused about the two rocket rivals.

This plan has the ability to put humans on the Moon by 2024, Bridenstine said. He then emphasized—twice—that NASA's chief of human spaceflight, William Gerstenmaier, has yet to bless this approach due to a number of technical details. His reservations include the challenge of integrating the Falcon Heavy rocket in a horizontal position and then loading Orion with fuel in a vertical configuration on the launchpad. The Falcon Heavy would also require a larger payload fairing than it normally flies with. This would place uncertain stress on the rocket's side-mounted boosters.

"It would require time [and] cost, and there is risk involved," Bridenstine said. "But guess what—if we're going to land boots on the Moon in 2024, we have time, and we have the ability to accept some risk and make some modifications. All of that is on the table. There is nothing sacred here that is off the table. And that is a potential capability that could help us land boots on the Moon in 2024."

With this comment, Bridenstine broke a political taboo. For the first time, really, a senior NASA official had opened the door to NASA flying its first crewed missions to the Moon on a Falcon Heavy rocket built by SpaceX. An official with the company did not immediately respond to a request for comment.

Some big hurdles

There are, of course, considerable caveats to consider here. For one, Bridenstine said the SLS rocket, with its larger throw capacity, is still the agency's preferred option. But that rocket's first launch has been delayed until at least late 2020, and there is no guarantee it will be ready to fly by then.

There is also the matter of Gerstenmaier, who was seated in the front row of Monday's town hall. On multiple occasions, Bridenstine referred to the influential US spaceflight leader along the lines of, "Gerst is going to be so mad at me for saying all of this." Sources have told Ars that Gerstenmaier has, in fact, not yet bought into any of this.

Finally, there is politics. It is not clear whether Democrats would support a policy like this put forth by the Trump administration, although in the past they have been somewhat more favorable to private space companies such as SpaceX. Certainly there will be opposition from key Republican senators, such as Alabama's Richard Shelby, who will oppose any effort to sideline the SLS rocket.

For all of that, however, Bridenstine reiterated Pence's line that the "ends" of reaching the Moon matter far more than the "means." And he encouraged the NASA workforce to embrace the possibility of change that would accelerate what has, until now, been a rather slow pace in human spaceflight. "This is a big charge, and it comes straight from the top," Bridenstine said. "It's a once-in-a-lifetime opportunity."