It sounds like something out of a cheesy science fiction novel, but scientists have long considered the possibility of creating an elevator that connects the Earth to the moon, making the trip between the two planetary bodies much easier. A number of practical considerations spring to mind immediately when contemplating such an endeavor, not the least of which is the financial cost of engineering and building such a system. A new paper, however, reaches the surprising conclusion that this barrier, among others, is not so great as to be prohibitive, and the reality of a space elevator may manifest within our lifetimes.
The paper, written by astronomy students Zephyr Penoyre and Emily Sandford and published on the online research archive arXiv, details a proposed “lunar space elevator” and describes the engineering difficulties involved in constructing one, as well as unique solutions to these problems. The students’ proposal leverages technology that already exists, instead of relying upon technology which has yet to be invented, by suggesting the construction of an elevator starting on the moon and reaching 200,000 miles to geostationary orbit.
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This construction method would eliminate the need to place a counterweight near Earth’s orbit to balance out the gravitational effects of building an elevator from the ground up to the moon, and also eliminates the risk of relative motion between the Earth and the moon to twist or bend the elevator. As this method attaches the elevator to a satellite in geostationary orbit, rather than the Earth’s surface, additional space travel is required to move from the Earth to the elevator, though the costs of this trip would be substantially less than the current cost of travelling to the moon.
The researchers propose that the cable used to support the elevator, which they call the Spaceline, would be thinner than a pencil and weigh about 88,000 pounds, which is within the possible payload weight of a rocket ship to the moon. A number of different materials could be used to create this Spaceline, including carbon nanotubes, a remarkably strong and light synthetic material which has so far only ever been produced in short lengths and is often considered in various space elevator designs.
A space elevator would make possible the establishment of a zero-gravity base camp in space, as well as an eventual moon base.
However, the researchers argue that other materials such as Kevlar, Dyneema, and Zylon, which are cheaper and easier to manufacture, could be used under their specifications. Though Penoyre and Sandford speculate that this project would easily cost a few billion dollars, the price is “within the whim of one particularly motivated billionaire,” bringing to mind the likes of Jeff Bezos and Elon Musk, both of whom have already invested significant portions of their personal fortunes into space exploration technology.
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Penoyre and Stanford also provide several practical justifications for investing in space elevator technology. The researchers argue that using a spaceline to move an elevator from geostationary orbit to the moon would be free, as the elevator could be powered by solar panels, and the cost of moving from the Earth to the elevator would be less than moving into a geostationary orbit. They also note that the development of this infrastructure would make transport of both people and materials across space much easier, and the engineering challenge of building a Spaceline would push forward technological capabilities. Additionally, a space elevator would make possible the establishment of a zero-gravity base camp in space, as well as an eventual moon base.
There are a number of scientific and economic advantages to returning to the moon generally. One potential application is the mining of valuable raw materials, such as helium-3, neodymium and gadolinium, which are thought to be buried beneath the moon’s surface. Helium-3, a rare material on Earth, could theoretically be used to fuel nuclear power generators, among other applications. The low-gravity vacuum of the moon has the potential to be a unique environment for scientific experiments, and establishing a human settlement on the moon would provide good experience for settling on other planets, most notably Mars.