In the first part of this series, we briefly investigated the current obstacles to space exploration. Now we will turn our attention once again to what we can do. We have already demonstrated our ability to go to and return from the Moon, as well as deploy robotic missions to Mars. To colonize the Moon or Mars, we will have to do much more than that, but the technology to go there and return already exists.
From the earliest days of the space race after World War Two, the Soviet space program and their American counterparts at NASA have planned and proposed permanent outposts throughout our solar system. Most of those plans are beyond the scope of this article, but there are a few worth looking at. A permanent base on the Moon appeared to be the next logical step in the American space program since the Apollo missions demonstrated our ability to put astronauts on the moon and bring them home.
The Soviet space program felt the same way and devised a plan to build just such a base years before their counterparts at NASA could beat them to it. Known in declassified documents as the Zvezda Moonbase, the Soviets intended to use the installation first as a military command post then expanded the concept for future development of their unrealized Lunar Expeditionary Complex. The goal overall was to create a sustainable human presence on the Moon before anyone else could, this was all part of the canceled N1-L3 lunar program overshadowed by the success of the American Apollo Program.
NASA also seriously studied building lunar outposts from the Project Horizon proposal to build a US Army fort in 1959, through the similar US Air Force Project Lunex in 1961, to a sub-surface base proposed in 1962 in the Sea of Tranquility. None of those proposals went very far, and with the cancellation of Soviet lunar exploration plans, the urgency to build an outpost on the moon waned quickly.
New interest in lunar exploration and settlement has come about slowly but surely as more national space programs and commercial interests have developed around the world. Robotic missions and new proposals from China, India, SpaceX, and Space Adventures has spurred a reevaluation of colonization of the Moon. Even the European Space Agency has been studying where to place permanent outposts for decades.
All of these proposals take the good with the bad when it comes to outposts on the Moon. On the one hand, the Moon is close to Earth, and we have over fifty years’ experience visiting, orbiting and returning from the Moon. On the other hand, as one of my favorite books about colonizing the Moon warns, “The Moon is a Harsh Mistress.” The Moon has long day and night cycles, temperature changes go from about -178 degrees Celsius to over 126 degrees Celsius between day and night, gravity there is about one-sixth of what we are used to on Earth, and the surface is awash in abrasive moon dust while it is constantly bombarded by radiation and micrometeoroids.
Most modern proposals for a colony (or colonies) on the Moon advocate for some kind of underground construction, either by covering the colony in lunar regolith (dust, soil, broken rock, and other materials) or finding and building in undiscovered lava tubes left over from long-dormant volcanic activity. These methods provide increased protection from radiation, micrometeoroids and air leaks from the colony. The tradeoff here is in increased construction complexity and potential difficulty in later expansion.
The alternative proposals are a variety of prefabricated surface modules, locally sourced modules constructed in-situ or a mixture of the two. Any surface structures would still require increased shielding from radiation, micrometeoroid impacts, and temperature extremes. Both the underground and surface options still have to contend with energy requirements through either solar or nuclear power or a blend of both.
In part three of this article, we will look at Martian colony options.