Joseph Silk is not a fantasist or science fiction author. He holds a doctorate in astronomy from Harvard University and taught astrophysics and cosmology at Oxford University. But what he wrote in his book Back to the Moon: The Next Giant Leap for Humankind will certainly seem like fantasy to many people: He suggests that humans should establish settlements on the moon – whole cities under the lunar landscape. Survival is possible, he explains, in the wide lava tubes that researchers have discovered on the moon. These underground caverns, he claims, could even be large enough to host entire cities and offer natural protection from any life-threatening solar-induced activity. Cities in these large lava tubes would also be shielded from meteorite impacts and could survive micrometeorite bombardments and the occasional violent solar eruption unscathed.
He also writes that regolith and water are sufficiently abundant to allow settlers to fabricate glassy bricks with which to construct dwellings. Additionally, Silk suggests, the water on the moon could be harnessed to produce fuel. This is important because the moon’s significantly lower gravity compared to Earth makes it an optimal launchpad for onward interplanetary missions. Silk acknowledges that tourism and the extraction of raw materials on the moon (e.g. rare earth elements) could be profitable economic sectors, but his real interest lies in the construction of gigantic telescopes on the far side of the moon. According to the astronomer, these could provide us with insights into the history of the universe that are beyond the capabilities of terrestrial telescopes or even the powerful telescopes already deployed in space.
Silk is convinced that humans will colonize Mars at a later date, but a seven-month journey to Mars with a subsequent return to Earth is currently “beyond our capability for human space flight.” The human exploration of Mars “is far in the future,” he states, and will only be possible decades from now.
Robert Zubrin takes a different view in his recently published book The New World on Mars. What We Can Create in the Red Planet. As the founder of the Mars Society, Zubrin has had a major impact on Elon Musk, whose goal is the colonization of Mars.
According to Zubrin, Mars presents numerous advantages over the moon, and in the distant future could even be turned into a second Earth through a process of “terraforming,” which is not possible on the moon. “Mars is endowed with all the resources needed to support not only life but also the development of a technological civilization. In contrast to Earth’s desert Moon, Mars possesses oceans of water in the form of huge glaciers and ice sheets, and it’s frozen into the soil as permafrost. It also holds vast quantities of carbon, nitrogen, hydrogen, and oxygen, all in forms readily accessible to those clever enough to use them … Virtually every element of significant interest to industry is known to exist on the Red Planet.” Mars therefore offers a wealth of raw materials and minerals that surpass those found on the moon, and more water can be extracted on Mars than on the moon.
Zubrin is much more optimistic than Silk regarding the feasibility of traveling to Mars. With the advent of Elon Musk’s impressive Starship, there are now viable technical means to reach Mars directly, eliminating the need for detours via the moon. Of course, Zubrin is also aware of the dangers posed by cosmic radiation on the long journey to Mars and the health impacts of such a long space flight (such as bone loss). However, he believes that these problems can be overcome and that the health risks from radiation have frequently been overstated.
According to Zubrin, the first Mars missions would probably be government-funded, However, the colonization of the planet would not be feasible with state funds alone and would only be possible with private-sector initiatives. The Mars colony could leverage its unique advantages, such as the fact that it is much easier and more cost-effective to access the resource-rich asteroids between Earth and Mars from Mars. Zubrin also believes that the challenging living conditions on Mars and the constant need to find novel solutions to problems would lead to an innovation boost, which would ultimately also benefit the economy on Earth.
There is consensus among authors such as Silk and Zubrin that humanity is on the verge of taking the next giant leap, namely the colonization of other celestial bodies. The only real difference between the two is that Silk prioritizes the moon as the first step, while Zubrin believes Mars should be humankind’s next frontier. As part of NASA’s Artemis program, which aims to establish a permanent station on the moon, the next human landing on the moon will probably take place this decade. However, Elon Musk has set his sights even further, with the ambitious goal of sending the first humans to Mars before the end of this decade.
A race is already brewing that, given what we know today, will probably be between Elon Musk’s SpaceX on the one hand and the Chinese on the other. The Chinese also have ambitious plans and want to send people to the moon this decade and to Mars in the following decade. One thing all the plans have in common is that this time it’s not about planting a flag in the ground and then spending the next few decades basking in the pride of that achievement, but about establishing permanent bases on both the moon and Mars, and exploiting these celestial bodies economically.
