According to one of the astronauts aboard NASA's 1968 Apollo 8 mission, it would be "stupid" and "almost ridiculous" to pursue a crewed mission to Mars.
"What's the imperative? What's pushing us to go to Mars? I don't think the public is that interested," said Bill Anders, who orbited the Moon before returning to Earth 50 years ago, in a new documentary by BBC Radio 5 Live.
Anders argued that there are plenty of things NASA could be doing that would be a better use of time and money, like the uncrewed InSight rover that recently touched down to study Mars' interior.
The comments, by one of the most accomplished space explorers in human history, illustrates a deep and public philosophical rift about whether the future of spaceflight will be characterized by splashy crewed missions or less expensive automated ones.
The crux of Anders' argument on the BBC boils down to his perception that NASA is fuelling a vicious cycle of highly-publicized missions that bolster its image, improve its funding, and attract top talent so that it can launch more highly-publicized missions.
Sending an astronaut to Mars would dominate the news cycle, but wouldn't push the frontier of practical scientific knowledge, Anders argued - a mismatch, essentially, between the priorities of NASA and those of the public.
That skepticism places Anders among the ranks of other high-profile critics of NASA, Elon Musk's SpaceX, and Jeff Bezos' Blue Origin - all three of which have set their sights on the Red Planet.
For instance, science communicator and advocate Bill Nye predicted last year that no layperson would want to settle Mars. Nye also doubled down last month to say that anyone planning on terraforming Mars must be high on drugs.
But Anders' own Apollo 8 crewmate Frank Borman disagreed, arguing in the documentary that crewed exploration is important.
"I'm not as critical of NASA as Bill is," Borman told BBC. "I firmly believe that we need robust exploration of our Solar System and I think man is part of that."
However, even Borman draws the line somewhere between exploration and settlement.
"I do think there's a lot of hype about Mars that is nonsense," Borman said. "Musk and Bezos, they're talking about putting colonies on Mars. That's nonsense."