At some point we will be going back to the Moon, not for just another flying visit or two, but to stay.
The Moon has almost no atmosphere, so we can build telescopes able to access all wavelengths, not just those not blocked by our atmosphere. Instruments supported by staff at a nearby base would be far more flexible and accessible than those in orbit, where any new instrument requires a space mission and has to survive the trauma of being launched. We could put radio telescopes on the far side of the Moon, where they wonít be reached by the worsening cacophony of radio interference we are generating on Earth. The solar wind directly impinges on the surface of the Moon, and will be easy to study. New experiments will just mean putting them outside, rather than planning another space mission.
The Moon will also be a good jumping off place for the exploration of the Solar System and beyond. The most expensive part of space missions is getting the spacecraft off the surface of the Earth and into space. The Moonís gravitational field is six times weaker that the Earthís and there is no air drag to worry about. We could even launch satellites using electromagnetic catapults. There are raw materials available locally, so we could build things there rather than here on Earth. However, to achieve these things we need to be able to live there.
The Moon has no atmosphere, so the colonists will have to make their own air to breathe. The Earthís atmosphere and magnetic field shield us from solar X-rays, ultraviolet radiation and high-energy particles. The Moon has neither, so they impact directly onto its surface. This is great for science, but not for long-term living. Science fiction stories have often depicted lunar bases as being enclosed in great plastic domes, which retain a breathable atmosphere. However, this provides little protection against solar X-rays and high-energy particles. In addition, with no atmosphere, the daily temperature variations on the lunar surface are huge: from around the boiling point of water during the day to far below zero during the night. The most feasible solution to these issues is to put the bases underground. Under a few metres of rock the temperature variations would be much smaller and most radiation would be blocked.
One big plus of having no atmosphere is that solar energy becomes very viable. Every lunar day is a clear and sunny one, and all the solar energy reaches the Moonís surface. Huge mirror heat collectors can provide heat for smelting minerals and solar cells can provide electricity. With energy and materials available locally, building spacecraft and launching them from the Moon is attractive.
The Apollo space missions found the Moon to be extremely dry, with a surface that has become vacuum-, heat- and freeze-dried over billions of years. A lack of local water would be a serious impediment to people living there. We use a lot of water, and shipping it all from Earth would be a problem. Now it looks as though that conclusion is wrong. Although most of the lunar surface is extremely dry, there is ice in permanently shaded craters near the Moonís poles. It is not clear where this water came from. It is possible it came from within the Moon or alternatively, it was brought by comets that collided with the Moon long ago. It has managed to persist on the surface because the Sunís heat never reaches it. Elsewhere on the Moon it would have been rapidly evaporated. Putting our base close to these water deposits will save us the problem of ferrying water from Earth. The water can be used for drinking and agriculture and by using electricity it can be converted to oxygen for breathing and hydrogen for use as rocket fuel. We will be going back to the Moon. Mankind has always been driven by an ìOutward Urgeî, which has not gone away.
Jupiter is in the southern sky after sunset; Mars and Saturn rise around midnight. The Moon will reach First Quarter on the 13th.
Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton.