Lunar Outposts

Someday humans will live on Earth's Moon. However, before permanent settlements are established, people will probably occupy a series of lunar outposts. Each outpost will be visited one or more times for a few days to as long as a few months so that specific tasks can be performed; when the jobs are finished, the occupants will leave. Visitors to a lunar outpost will have to take with them almost everything they will need there, including the food they will eat and the air they will breathe.

The Apollo Outposts

The Apollo program of the National Aeronautics and Space Administration (NASA) placed six lunar outposts on the Moon between July 1969 and December 1972. Each one was part of a lunar landing mission during which two American astronauts landed a spacecraft on the surface of the Moon. The astronauts traveled on the surface of the Moon to place scientific instruments and gather geologic samples and then returned to orbit to rejoin the main spacecraft, in which another astronaut had been orbiting the Moon. Part of the landing craft remained on the Moon to be used as a launch platform; the rest was used to carry the astronauts back to lunar orbit. After the astronauts transferred everything necessary back to the main spacecraft, the landing craft was crashed onto the Moon. One reason for crashing the landers was to provide signals for the seismometers the astronauts had placed on the surface to study moonquakes.

Future Outposts

The Apollo missions were designed as brief visits to a variety of locations, and so there was no reason to establish reusable outposts. In the future, lunar outposts may be designed differently. Scientists have studied the rocks and soil returned from the Moon by the Apollo astronauts and have used telescopic and spacecraft observations to learn a great deal about the lunar environment. It is likely that future outposts will be located in areas that scientists want to study in more detail and will be more permanent facilities that can be visited more than once.

All future lunar outposts will have some features in common. The primary function of each outpost will be to keep the people who visit it alive. This includes protecting them from danger and providing what they need to remain healthy. Dangers in the lunar environment include radiation, extreme temperatures, and the vacuum of space. The Moon has almost no atmosphere, so the Apollo astronauts had to wear space suits when they left the landing craft. Any future lunar outpost will need to be airtight so that its visitors will be able to remove their space suits after they enter. An airlock would help reduce the amount of air lost to space each time someone entered or left the outpost.

Earth's atmosphere protects people from much of the harmful radiation produced by the Sun and moderates the temperatures on the planet's surface. The Moon lacks this natural protection, and so lunar outposts must protect their visitors. The longer people stay on the Moon, the more protection from radiation the outpost must provide, because the effects are cumulative. One way to protect against radiation is to shield the outpost with rock or soil. The surface of the Moon is covered by a soil layer called regolith, which has been produced by meteorite impact. This layer can be moved relatively easily to cover the outposts. A layer a few meters thick would protect the people inside from radiation. It also would help insulate the outpost and make it easier to maintain a comfortable temperature inside.

People need to eat food, drink water, and breathe air, and all these things must be taken along with them to a lunar outpost. These materials are all cycled through the body and turned into waste products, and so there must be toilets and air purification equipment to maintain a healthy environment.

The Purpose of Future Outposts

Other features of lunar outposts will depend on the tasks to be performed. Some activities of the Apollo astronauts will probably be repeated at future lunar outposts. Scientific instrument packages will be put in place, maintained, and serviced in order to provide information on the lunar environment, surface, and interior. Geologic fieldwork will be performed; samples of rock and soil will be gathered for this purpose. Some human exploration will be done, although robotic explorers, perhaps controlled remotely by people at the outpost, probably will also be used.

One scientific endeavor for which the Moon is well suited is astronomy. Although the lack of an atmosphere is a problem in terms of life support, it makes the Moon an almost ideal platform for astronomy. Because the Moon turns on its axis only once a month, targets may be observed continuously for many days. Light is not lost or distorted by traveling through air, and so even a small telescope can make useful observations. The farside of the Moon is the only place in the solar system that is always shielded from radio waves coming from Earth, and so it is a perfect place for radioastronomy. The Moon's weaker gravity, only one-sixth that of Earth, will make it possible to build bigger telescopes on the Moon than can be built on Earth.

Some outposts will probably be utilized to test technologies that will be used later in more permanently occupied bases. Some of these technologies will relate to maintenance of the bases, such as automated greenhouses to grow food and recycle carbon dioxide. Other technologies to be tested will include the extraction of hydrogen, oxygen, and other gases from lunar rocks and soil. The hydrogen and oxygen can be used for fuel, water, and breathing. Helium eventually may be used in fusion reactors to produce power.

The next lunar outposts could be constructed by NASA, a cooperating group of nations, a government-industry partnership, or even private for-profit companies. Lunar outposts have been built before, and more can be built in the future.

see also Asteroid Mining (volume 4); Closed Ecosystems (volume 3); Habitats (volume 3); Living on Other Worlds (volume 4); Lunar Bases (volume 4); Moon (volume 2); Power, Methods of Generating (volume 4); Resource Utilization (volume 4); Scientific Research (volume 4); Settlements (volume 4); Space Industries (volume 4).

Chris A. Peterson

Bibliography

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Burns, Jack O., Nebojsa Duric, G. Jeffrey Taylor, and Stewart W. Johnson. "Observatories on the Moon."Scientific American 262 (1990):42-49.

Chaikin, Andrew. A Man on the Moon: The Voyages of the Apollo Astronauts. New York:Viking Press, 1994.

Spudis, Paul D. The Once and Future Moon. Washington, DC: Smithsonian Institution Press, 1996.

Taylor, G. Jeffrey, and Paul D. Spudis, eds. Geoscience and a Lunar Base: A Comprehensive Plan for Lunar Exploration. Washington, DC: NASA Conference Publication 3070, 1990.

Wilhelms, Don E. To a Rocky Moon: A Geologist's History of Lunar Exploration. Tucson: University of Arizona Press, 1993.