WEEKLY WHINE

Realization of launch potential

What are some potential ways of increasing Earth's materials supply? One promising method might be to increase mining area, not on Earth, but on Earth's Moon. The lunar surface contains some minerals that may be helpful in constructing a long-term method of higher materials reclamation. For example, the Moon contains a number of H₂ deposits, some He, and perhaps small amounts of ice water, many of which would be necessary for a lunar base.

But what about elsewhere? The lunar regolith contains a number of important oxides that would be beneficial as construction materials and other functions. These could be used not only in space, but in Earth's private sector as well. Although the Moon certainly lacks the rare and precious materials that can be found on Earth in comparative abundance, it does have these resources as well as various other metals. Once these items can be obtained, they can be put to use on Earth, since there are no significant differences with the same resources when found on Earth, only that the relative ratios are more favourable.

So is it really feasible to expect that materials may be retrieved from the Moon, shipped all the way to Earth, and utilised at a low cost? At this point, obviously not. No nation is currently planning on any manned trip to the Moon, let alone establishment of a base there. When a base is established, it would be primarily a research outpost, and mining would only come later. It would be a high initial investment, but theoretically, it carries the potential of great profits.

The essential components would, unsurprisingly, begin with the mine itself. Early in the next century, research into extraterrestrial mining is expected to yield a realistic means by which materials may be extracted from the Moon. Then, they would be transported to Earth, starting with launch off the lunar surface. Mass drivers, or rail guns, would be a potential source of energy for this purpose. This would use a series of electromagnets to accelerate a conducting projectile to escape velocity. The projectile, of course, would be the vehicle containing a metric ton or whatever of lunar ore. From then, it would be brought to processing plants, either in lunar orbit, Earth orbit, or perhaps located at one of the first two Lagrange points. Each gravitational system containing two bodies has five Lagrange points associated with the smaller body, points at which gravitational forces conspire to hold a mass at that point. L₁, the first Lagrange point, is that at which Earth's gravity balances the Moon's gravity. L₂ and L₃ are also found along the Earth-Moon line, with the second point a bit closer to the Moon and the third point actually behind the Moon. L₄ is located 60° ahead of the Moon in its orbit, whilst L₅ trails the Moon by 60°. The five points do vary in one critical property. L₄ and L₅ are stable, but the first three points are not, ie, when a mass at either L₄ or L₅ deviates in the slightest from that point, gravitation will bring it back to the Lagrange point. However, at L₁, L₂, and L₃, when a mass moves a tiny bit away, gravitational forces will be imbalanced such that the object will tend away from the Lagrange point, probably toward either Earth or the Moon. The purpose of locating something at a Lagrange point would be to ensure that it stays in the same place relative to the lunar surface, so that the mass driver may launch the cargo along a straight line to processing plants located at, say, L₁.

Obviously, this type of technology is far in the future, but continued research will bring about gradual cost reduction until it's something that Congress might actually feel like doing.