Rare earth elements and helium are just some of the resources scientists
believe are abundant on the Moon. The problem is how to get them here.
Rockets are not cost-efficient, otherwise, we would have already colonized
our natural satellite. Yet there is an alternative to rockets and it might
have just got doable: a lunar elevator.
Two astronomy students from the University of Cambridge and Columbia
University recently published a paper
on an invention dubbed Spaceline—a space elevator they say could be built
with existing technology and would cost only about $1 billion. And it would
be easy to build.
“By extending a line, anchored on the moon, to deep within Earth’s gravity
well, we can construct a stable, traversable cable allowing free movement
from the vicinity of Earth to the Moon’s surface. With current materials, it
is feasible to build a cable extending to close to the height of
geostationary orbit, allowing easy traversal and construction between the
Earth and the Moon,” Zephyr Penoyre and Emily Sandford write in the abstract
of their paper.
A cable to the Moon may sound like something out of a cartoon, but Penoyre
and Sandford are not joking. According to their idea, travellers to the Moon
would fly to the end of the cable on spacecraft and then transfer to
solar-powered autonomous vehicles that would climb the cable to the Moon. The
cable itself could be no thicker than the lead of a pencil and made from
Kevlar, which is much cheaper than other materials considered for a space
elevator.
Of course, the question everyone would ask is, why bother building a space
elevator to the Moon. True, there are potentially valuable minerals on the
Moon, but we have yet to determine if their mining is commercially viable.
But there is another reason a cheap enough space elevator could make sense:
helium-3.
Helium-3, many
believe, is the solution to the nuclear fusion problem, that is, how to make
it work. The element is scarce on Earth but thought to be abundant on the
Moon, with several governments eyeing lunar mining to get their hands on it.
The reason is helium-3 is a potentially much more efficient fuel for nuclear fusion
reactors than what researchers currently have access to on Earth. Combined
with deuterium—already used in nuclear fusion reactors—it turns into regular
helium with a single proton as a by-product, meaning a lot less energy waste
than other elements. What’s more, a deuterium-helium-3 fusion reaction would
be much easier to contain. Related:
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Yet not everybody shares the enthusiasm about helium-3. One critic,
planetary science and astrobiology professor Ian Crawford, for example, has likened helium-3 to
fossil fuels.
"It's a fossil fuel reserve. Like mining all the coal or mining all
the oil, once you've mined it … it's gone," Crawford told Space.com a
few years ago. According to him, mining helium-3 on the Moon would require
massive investments that do not justify the whole endeavor. With technology
moving relentlessly forward and previously expensive infrastructure becoming
cheaper thanks to this fact, the investment in helium-3 mining may not need
to be that massive.
However, the Spaceline has yet to prove its viability.
“A space elevator is like a railroad — you don’t build it unless you
expect a lot of railroad traffic,” physicist Marshall Eubanks told
NBC News. And that’s just a commercial concern. A much more serious one has
to do with safety: satellites orbiting the Earth could collide with the
cable.
These are just a couple of potential problems with the Spaceline and other
lunar elevator ideas. Because of these problems, it’s no wonder space
agencies have not been all too enthusiastic about the whole idea of linking
the Earth with the Moon via an elevator. It seems despite the promise of such
ideas, it will be a while before we get our hands on the lunar helium-3.
By Irina Slav for Oilprice.com
