Advocates of space exploration and colonization debate whether the United States should pursue a Mars-first or Moon-first policy. Broadly speaking, four driving forces will impel the exploration and colonization of celestial structures in our solar system: scientific inquiry, commerce, geopolitics, and the yearning to create new societies. As we examine each in turn, we will see that the logic strongly favors a focus on the Moon.
Scientific inquiry. Establishing outposts on moons, planets, or asteroids will enable the nations of the Earth to conduct scientific investigations that yield insights into the nature of the universe in which we live. The ability to peer into space without the obscuring effect of Earth’s atmospheric blanket and to gather physical samples from various heavenly objects will advance our knowledge of astronomy, physics, geology, weather dynamics, the origins of the Earth, the origins of the cosmos, and much more. Man’s quest for knowledge is limitless. Space exploration will allow us to push those limits.
However, it is not obvious that Mars is any better a candidate for conducting these inquiries than the Moon. On the one hand, Mars is more similar to Earth than the Moon. It has stronger gravity. It has a semblance of an atmosphere. And it is more geologically active. No question, there is much to be learned from the red planet, and humans will want to establish settlements on it one day. But there is just as much, if not more, to be learned from the Moon.
The Moon has essentially zero atmosphere, making it an ideal platform for telescopes and sensors peering into the stars. Moreover, the Moon, ripped from the Earth in a massive collision in the early eons of the solar system, enjoys a shared history with our planet. A study of early lunar geology will lend more insight into the Earth’s early geology than a study of Mars ever could. Perhaps most important, the lack of atmosphere and significant geological activity over the past two or three billion years has left the lunar surface undisturbed by the forces of erosion. A study of the age and composition of lunar craters can tell us much about the incidence of wandering, extra-planetary bodies in the solar system over the millennia.
For purposes of argument, let us posit that the examination of both the Moon and Mars both have scientific value and that, for this, the first of our four criteria, the case for settling one or the other is a draw.
Commerce. When it comes to commerce, there is no comparison between the Moon and Mars. The Moon wins hands down. Due to its proximity to Earth — allowing for near-instantaneous communication and two-three days’ travel time — the destiny of the Moon is to form part of an integrated Earth/Moon economic system. By contrast, the length of time it takes for communications to reach Mars from Earth and return — 3 to 22 minutes one way, depending upon the relative position of the two planets — effectively makes telephone conversations impossible, greatly impeding commerce. Travel time between Earth and Mars is roughly seven months, comparable the time it took to travel in the 16th century between Portugal or the Netherlands to the spice islands of the East Indies. To be sure, there was an economic connection in the age of sail between homeland and colony but it was tenuous. The links were worth maintaining because the East Indies had something — cloves, cinnamon, nutmeg, mace — worth trading. There is little prospect of Mars producing anything the Earth wants or needs within the foreseeable future.
By contrast, the Moon is an extension of cislunar space, and cislunar space is fast becoming a critical adjunct to Earth’s economy. As of 2019 there were nearly 5,000 satellites orbiting the Earth: satellites for telecommunications, satellites for weather tracking, satellites for remote sensing, and satellites for military purposes. In the future there will be many thousands more. We could see orbiting manufacturing facilities that exploit the unique properties of near-zero gravity and the vacuum of space. We could see vast arrays to collect solar energy and beam it to earth. Undoubtedly, we will see orbiting military stations armed with sensors, nuclear weapons and hypersonic missiles. Due to Earth’s gravity well and the incredible expense of launching material into orbit, maintaining this multi-trillion-dollar cislunar economy will be conducted most cost-effectively from the Moon. Servicing cislunar assets will provide a stable economic underpinning for the lunar economy.
Any additional exports of products or services from the Moon is pure bonus. One much-discussed possibility is the mining, refining and export of He-3, the helium isotope that many hope will fuel radioactive-free nuclear fusion (assuming fusion becomes practicable). Similarly, the Moon could function as a near-Earth platform for the exploration and colonization of the solar system. In theory, it will be cheaper to mine frozen water from lunar craters never exposed to the sun and convert it into rocket propellant than to lift the fuel out of the Earth’s gravity well. Finally, as colonies implant themselves on the Moon, they could become centers for fabrication and manufacturing themselves. The Mars-first vision views the Moon as little more than a cislunar gas station, but the orb’s close proximity will make it Earth’s invaluable economic satellite.
Geopolitics. Sadly, the destiny of nations is to seek military advantage over their peers and competitors, and there is no evidence to suggest that dynamic will change in the near future. In the U.S., which has the world’s most technologically advanced military, modern warfare depends upon satellite communications for remote sensing and communications. Understanding this dependence, rising powers such as China seek the means to disrupt those communications by developing the capacity to destroy those satellites. In turn, the U.S. military is developing the means to defend its satellites — hence the recent creation of the U.S. Space Force.
The military arms race will lead ineluctably to the establishment of weapons platforms in orbit. Those systems will evolve, adding more armor, electronic defenses, and secondary weapons systems to protect the platforms themselves. Like an expanding board of the ancient oriental game of Go, military systems will leapfrog to the Moon, where it will be possible to erect stable, highly fortified weapons platforms. In a very real sense, to quote Javier Rodriguez from “Dust Mites,” “He who controls the Moon controls cislunar space. And he who controls cislunar space dominates the Earth.” As long as other great powers are capable of mobilizing the resources to build a space-based military — and China seems a formidable enough adversary to do so — the U.S. will need to stay a step ahead. It may take several decades, but the hopscotching of weapons systems from Earth to orbit to the Moon is inevitable,
By contrast, there is no prospect that Mars will become an integral part of U.S. military planning in the 21st century.
New worlds, new societies. Just as it is inevitable that the quest for military dominance will impel humans into space, so it is inevitable that a yearning for economic, religious and ideological freedom will spur humans to contemplate settling the Moon, Mars, asteroids, or even the moons of distant planets. Persecuted religious and ethnic groups — Jews, Mormons, libertarians, hippie communes, personality-driven cults, cyber-collectives, or entities we cannot yet imagine — will flee Earth just as the Puritans, Quakers and Catholics fled England to forge societies in their own image. Some may strive to create colonies in cislunar space, others on the Moon. And others, seeking to vault as far from the rest of humanity as they, may pitch camp on Mars. Any such colonies located within the Earth-Moon economic system have a much greater chance of long-term survival, however, than colonies established in the depths of space living an isolated and precarious existence. In the competition between the Moon and Mars, consider the “new worlds” motive a draw.
In sum, of the four forces propelling settlement and colonization, the two most powerful, commerce and the military, favor the Moon and two others are inconclusive. Utopians might find freedom anywhere in the solar system, including Mars, but those who participate in the Earth-Moon economic system are far more likely to prosper and grow in numbers. The quest for scientific knowledge will support outposts on the Moon and Mars alike, but lunar scientific settlements will find support from other lunar colonies while expeditions to the Moon will lead an existence as lonely as the outposts in Antarctica.
It is common sense for U.S. government and industry to prioritize the moon or planet that holds out the greatest economic, business, and military return on investment. And that means the Moon, not Mars.