Vice President Pence speaks at the National Space Council meeting in Huntsville, Ala., on Tuesday. (Eric Schultz/AP)

VICE PRESIDENT PENCE wants America to boldly go where man has gone before: the moon, and fast. He announced Tuesday that NASA has five years to put humans back on the lunar surface “by any means necessary.” If the agency cannot do that, he said, it is NASA that will have to change — not the mission.

The hurry with which the Trump administration seems determined to carry out so ambitious an aim makes clear that the primary goal is to advance not science but the image of U.S. dominance. China landed a spacecraft on the moon’s far side this year. An Israeli craft is in orbit and scheduled to land soon, and India plans to follow. The United States blasted off in the 1960s not only because it was difficult but also because officials wanted to show we could do something hard more quickly than our adversaries. Now, the nation is eager to prove itself again.

Is the administration prepared to back its bluster with cash? NASA has a limited budget, and President Trump’s requests to Congress suggests funding will become scarcer still. Another trip to the lunar surface would cost an estimated $100 billion or more. Keeping astronauts there for extended periods of time would be even pricier. Robotic probes, on the other hand, can provide answers to compelling scientific questions on the comparative cheap. The Opportunity rover to Mars survived on the red planet for 15 years and cost only $800 million. The Cassini spacecraft’s 20-year trip around the solar system found the building blocks of life on one of Saturn’s moons, and Juno is still hovering above Jupiter to study the universe’s origins.

There is surely important science humans could do on the moon that robots cannot carry out on their own. Experimenting with building on the surface, too, could help pave the way for commercial activity in space. And one way to figure out whether humans can survive on a celestial body is to put them on a celestial body — which is perhaps a more productive enterprise than having them float around above it in a $100 billion space station. But pretty as the concept of plopping astronauts down to, as Mr. Pence said, “mine oxygen from lunar rocks that will refuel our ships” or “extract water from the . . . craters of the south pole” may be, we don’t know how to do any of that yet. How do we start figuring it out? Send some robots.

There are bad reasons to go back to the moon, and there are better ones. Sticking another American flag in the ground just to watch it wave will accomplish little. Anyone calling for the 21st-century lunar renaissance should be thoughtful about the space program’s goals and honest about the costs. Under this administration, unfortunately, that may be too much to ask.