A few months ago, when European Space Agency director general Johann-Dietrich Woerner laid out a vision for his agency to lead the way in establishing an international Moon Village, I had a feeling of déjà vu. In January 2004 President George W. Bush announced his own Vision for Space Exploration, in which the U.S. would lead the world back to the moon. Once we had gone there, and humans had learned to live and work successfully on another world, we would head on to Mars as the ultimate destination.

Bush's idea was inspiring enough that, in addition to NASA, no fewer than 13 international space agencies signed on to participate in developing a plan for reaching the moon. Unfortunately, the plan's implementation was badly flawed. NASA tried to relive the glory days of Apollo by focusing on one-use vehicles that would transport everything to the moon from Earth. Apollo was a fantastic achievement, but it was not sustainable, which was in part why the program was canceled in the early 1970s. Bush's vision proved too expensive to sustain as well, and in 2010 President Barack Obama declared that the U.S. had no need to go back to the moon, saying, in essence, that we've been there, done that. Instead, he said, we would go to Mars without taking that interim step.

But a return to the moon is crucial to the future of human space exploration—and not just for the experience it would give us in off-world living. Our satellite is also rich in resources, notably water ice, which can be split via electrolysis into oxygen and hydrogen. These elements can then be used in fuel cells and in making liquid rocket fuel. If we are ultimately heading to Mars (or anywhere else), hauling that fuel off the surface of Earth is terribly inefficient. Much better to launch it from the moon, where gravity is one sixth as strong.

A return to the moon could also inspire the next generation and advance technology just as Apollo did—but do so in a sustainable, stepwise manner. The taxpayer needs to see a return on investment for this endeavor and not only in technology development. For example, a spacecraft-refueling depot orbiting the moon—supplied with fuel refined from lunar resources, privately operated and selling its products to various space agencies—is one commercial on-ramp to bring the moon into our economic sphere of influence. Such activities could result in a major reduction in launch mass from Earth's surface, thereby cutting the cost of space missions. This has the potential to create a slew of industries that in turn create high-tech and well-paid jobs.

The immediate next step in lunar exploration should be robotic prospectors on the lunar surface to define the extent, form, distribution, and ease of extractability and refinement of those resources identified from orbit. An international effort could facilitate this critical operation. NASA does have a Resource Prospector mission in development, but it is being done on a shoestring budget that could be cut at any time. Russia also has a Lunar-Resurs program under development, partnering closely with the European Space Agency. And let us not forget China, which became in 2013 the third nation to successfully soft-land on the moon. China plans to return lunar samples to Earth within the next couple of years, again following the U.S. and Russia.

Currently the U.S. vision for human space exploration is to use a robotic spacecraft to capture a small boulder from an asteroid, about one meter in diameter, and redirect it to an orbit around the moon. Humans will then explore that boulder as practice for an eventual voyage to Mars. But this so-called Asteroid Redirect Mission will have no applicability to Mars, largely because working in microgravity is a very different proposition from working on the surface of a planet. Basically, it is a fast track to nowhere.

Which brings us back to Woerner's Moon Village, which spacefaring nations applauded when it was presented at the ESA-led “Moon 2020-2030” meeting last December. Right now the U.S. is standing on the sidelines, watching other nations move on. Yes, Mars is the ultimate destination, but our country has an ill-defined pathway on how to get there. The moon is the enabling asset and the key to our achieving that goal. We need to redefine the way we look at human space exploration such that any money spent on space travel can be viewed as an investment in the future.