The physical infrastructure on the Moon will be critical to any long-term human presence there, as both America and China prepare for a permanent human presence on the Moon. A self-deploying tower is increasingly one of the most important parts of this physical infrastructure. These towers can support a variety of equipment, from solar panels to communications equipment, and the more weight they can withstand the moon's gravity, the more powerful they are. Therefore, it is important to understand the best structural design for these towers. This is the goal of recent work by researchers at North Carolina State University and NASA's Langley Research Center.
Several technologies underlie this structure, which was developed as part of NASA's Self-Erectable Lunar Tower for Instruments (SELTI) project. One of the most important technologies is the material from which the tower is made. In their study, researchers examined two types of materials: the corrugated rollable tube mast (COROTUB) and the collapsible tube mast (CTM).
Let’s first look at the design around COROTUB. COROTUB is a patented technology developed for use with small satellites. For example, it would allow a CubeSat to deploy an antenna many times larger while still being packed into a relatively compact package. Adapting the technology to an extendable boom mast for use on the moon is an obvious next step.
Fraser discusses why we should return to the moon.
CTM, on the other hand, is commercially available from Opterus. It is designed to roll flat into a shape similar to a roll of tape. Once extended, it can carry a payload located at the top of the mast. Its design seems much simpler than COROTUB's, but on the surface they have almost the same weight limitations.
However, one of the most important features of these towers lies not in the boom material itself, but in the supporting structure – in this case a cable. The article looks at designs with and without support cables that could counteract the force of the instruments at the tip of the boom and force them to tilt to one side. Imagine a giant sunflower with its pedals bending to one side, but on the other side it's held in place by a metal cable.
The systems with this supportive cable structure perform better in almost all measures used by the authors. The methods they used included a type of mathematical analysis known as the Rayleigh-Ritz method, typically used to calculate loads on structures. But the calculation of these structures on the Moon is different from that on Earth. For one thing, much less gravity and no wind would require additional support.
Isaac Arthur is exploring the possibility of using the moon as an industrial center – presumably this would involve building towers.
Credit – Science and Futurism with Isaac Arthur YouTube channel
However, the system must experience enormous temperature differences depending on whether it is on the illuminated or unilluminated side of the moon. These did not initially appear to be part of the calculations used in the analysis.
COROTUB and CMT are not the only potential technologies that want to solve this problem either. We previously reported on Honeybee Robotics' LUNARSABER project, whose 100m tall masts would solve a similar problem as the COROTUB and CMT-based towers. While it remains to be seen what technology will be used in a full prototype on the moon, the fact that more than one organization is looking at the technology is a promising indication. And since housing literal lights is one of the use cases of these towers, it's only a matter of time before more light shines on this technology – and the lunar surface below.
Learn more:
J Daye, A Lee and J Fernandez – Structural architectures for self-erecting lunar towers
UT – A tower on the moon could provide astronauts with light, power and guidance
UT – NASA's new solar sail extends and sets sail
UT – A lunar base needs a transportation system
Mission statement:
Artist's conception of a moon base.
Photo credit – ESA – P. Carril
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