Chapter 5: The Earth-Moon System

Neil Armstrong (1930–2012), commander of NASA's Apollo 11 mission, descends the ladder of the Apollo Lunar Module (or Lunar Excursion Module, LEM) to become the first human to set foot on the surface of the Moon.

Almost forgotten in the more than fifty years since we set foot on the Moon is the fact that NASA then had an aggressive plan for lunar exploration that would have culminated in a Moon base by 1980. Over the course of six Apollo landings, the time spent on the surface was extended from one to three days, the spacesuits were upgraded to allow moonwalks of up to seven hours, and the electric-powered rover was added to the mix. In 1968, as NASA prepared for its first piloted Apollo flight, it formed a working group to study the idea of a lunar station. After three exploratory missions to different landing sites, NASA would have sent six or more missions to a single site as preparation for a permanent base. The working group began its report by declaring that a twelve-astronaut International Scientific Lunar Observatory should be a major goal for the agency.

An artist's concept of a possible Moon colony. Just a few kilometers from the Apollo 17 Taurus Littrow landing site, a lunar mining facility harvests oxygen from the resource-rich volcanic soil of the eastern Mare Serenitatis. Here a marketing executive describes the high iron, aluminum, magnesium, and titanium content in the processed tailings, which could be used as raw material for a lunar metals production plant. This image produced for NASA by Pat Rawlings, (SAIC). Technical concepts for NASA's Exploration Office, Johnson Space Center (JSC).

The working group's recommended option was to develop new hardware to form the nucleus of a future base. A new Lunar Payload Module with a descent stage but no ascent stage would carry 7,000 pounds to the surface. Its heaviest item of cargo would be a one-ton shelter capable of housing two people for two weeks. It would also deposit two snazzy personal jetpacks for ranging over the surface and a rover or Moon buggy that could be driven by an astronaut or by flight controllers in Houston. The payload would also have included a solar furnace to test the extraction of useful ingredients from the soil, a one-foot telescope, a bioscience package, and various pieces of lab equipment. NASA’s advisory group estimated that doing the groundwork for a lunar base would add a billion dollars to the projected cost of the Apollo program.

It was a great idea but it ran into the buzzsaw of political reality. NASA's budget peaked in 1965, during the white heat of development for the Moon landings, at $5.25 billion, or 5 percent of the federal budget. President Lyndon Johnson was a staunch NASA supporter, but the cost of the Vietnam War soared to $25 billion in 1967 and Congress was looking to cut costs. After the euphoria of Neil Armstrong’s historic step, public interest waned and NASA’s budget went into sharp reverse.

Inflatable module for lunar base: With a number of studies ongoing for possible lunar expeditions, many concepts for living and working on Earth's natural satellite have been examined. This art concept reflects the evaluation and study at JSC by the Man Systems Division and Johnson Engineering personnel. A 16 meter diameter inflatable habitat such as the one depicted here could accommodate the needs of a dozen astronauts living and working on the surface of the Moon. Depicted are astronauts exercising, a base operations center, a pressurized lunar rover, a small clean room, a fully equipped life sciences lab, a lunar lander, selenological work, hydroponic gardens, a wardroom, private crew quarters, dust-removing devices for lunar surface work and an airlock.

In 2009, the Center for Strategic and International Studies produced an estimate of the cost of a lunar base. They assumed that a heavy-lift rocket will exist, and since at least three countries are likely to have such a capability, it's a fairly safe assumption. The project development costs were estimated at $35 billion, which is much cheaper than the $130 billion price of the International Space Station and, if spread over a decade, no more than the costs of flying the Space Shuttle. Base operating costs were estimated at $7.4 billion per year. Half of the operating costs come from assuming that no local resources would be available, so four tons of supplies per person per year would have to be shipped from the Earth to the Moon. The basic requirements per day per astronaut (assuming water is efficiently recycled) would be 2.5 liters (or 2.5 kg) of water for drinking and adding to food, 0.8 kg of oxygen, and 1.8 kg of dried food. The other central requirement is energy in the form of solar power. 

Clearly, a lunar base would be more attainable if it could be as self-sufficient as possible. The Moon was always thought of as a sterile, arid, meteor-blasted rock, so there was much excitement when orbiters sent back evidence of water in the mid-1990s. A number of craters, such as Shackleton crater, appeared to have high amounts of hydrogen, possibly suggesting water ice. In 2010, an Indian satellite found ice in the permanently shadowed regions of craters near the Moon’s north pole. This led to research showing that the Moon contains 600 million tons of ice in nearly pure sheets several meters thick. The other key ingredient for a lunar base is oxygen to breathe. The lunar soil or regolith is 40 to 45 percent oxygen by mass; it's fairly simple chemistry to heat it to 2,500 Kelvin using solar power and unlock it from minerals to generate 100 grams of breathable oxygen for every kilogram of soil. Water could also be split into oxygen and hydrogen, the main components of rocket fuel.

Even the material for a habitat could be created locally. Lunar soil is a unique blend of silica and iron-bearing minerals that can be fused into a glass-like solid using microwaves. Fairly simple technology can turn the dirt into hard ceramic bricks. The European Space Agency is developing a 3-D printer that can create wall blocks at three meters per hour, fast enough to build a whole habitat in a week. The cost of a Moon base shrinks dramatically if air, water, and building materials can be generated locally. All of the technologies needed to do it have been demonstrated in the lab.

Location, location, location. It's as crucial when buying a home as when planning a Moon base. The best spots are high mountains on the rims of large craters near the poles. They would be close to abundant water ice but high enough to be peaks of eternal light, always illuminated by the Sun so with access to solar energy all the time. At low latitudes, colonists would have to contend with extreme temperature variations, plus the 354-hour-long lunar night. But they could make use of one of the tunnels formed long ago when basaltic lava flowed on the Moon. The lava tubes can be as wide as 300 meters. They maintain a stable temperature of –20°C as well as provide protection from cosmic rays and meteorites. As you can see, past estimates of when there might be a Moon base were wildly optimistic, so we should take current estimates with a pinch of salt. The Chinese plan to build a Moon base by the late 2020s, and the U.S. and Europe, in partnership, hope to establish a base by the early 2030s.