Microwaves aren’t just useful for reheating leftovers. They can also set up landing pads on other worlds – at least according to a study published by a consortium of scientists from the University of Central Florida, Arizona State University and Cislune, a private company. Her research shows how a combination of sorting the lunar soil and then blasting it with microwaves can create a landing pad for future rockets on the moon – and save any surrounding buildings from being blown up by dust particles traveling at 10,000 km/h.
This system works in large part because certain minerals on the moon’s surface are magnetic, and these same minerals are also very susceptible to microwave heating. In particular, a type of glassy mineral called ilmenite, which makes up about 1-2% of the lunar surface, is highly magnetic.
Ilmenite is formed when the moon is hit by small meteors, forming material called agglutinates. Older lunar soils (that is, those not recently destroyed by a meteor) have up to 60% of the soil composed of these agglutinates, while “younger” lunar soils have only about 20%. So the concentrations are high enough in some places that contain significant amounts of older regolith.
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According to this UT interview, understanding regolith will be key to building any type of lunar base.
So if future researchers wanted to build a landing pad, they could zap this older soil with powerful microwaves to sinter it together and create a durable enough surface for a rocket to land on without having to sandblast everything around it. This sandblasting would be particularly nasty since there is no air to slow down the dust particles like there would be on Earth.
The solution seems simple enough – irradiate the soil with microwaves to sinter it together. Systems can always be improved, however, and this microwave sintering process is no exception. The researchers found that by subjecting the regolith to a process known as conditioning, they could increase the amount of microwaves absorbed and thus the effectiveness of the heating process.
The preparation in this case involves sieving the soil and hitting it with a magnetic field, causing the more magnetic soil to move toward the magnet, while the non-magnetic soil simply falls back to the ground. dr Phil Metzger, one of the lead authors of the study, compares the process to what recyclers do here on Earth – they sort material by its magnetic strength, which allows magnetic material, like regular steel, to be separated from more valuable stainless steel, which is non-magnetic .
In this UT video, we describe why in situ resource utilization is useful for all sorts of things.
If the magnet on the moon is turned off, the magnetic earth would be on the non-magnetic type. And since magnetic soil is also much more susceptible to microwaves, the treatment process could increase the amount of energy the material absorbs by 60-80%.
That’s an absurd improvement, and one that could dramatically reduce the necessary size of the microwave power supply needed for such a mission. Given the weight of some microwave power supplies, any reduction in their weight could dramatically lower the cost of the overall program.
The paper also looks at other potential methods of creating landing pads, including polymer-based through pavement-based pads. However, the cost effectiveness of using in situ resources, such as those found in the microwave sintering project, is most effective at the current price point to put devices into orbit.
While that price could drop significantly in the coming decades, this technique appears to be one of the best for Artemis mission planners hoping to land a reusable rocket on the moon within this decade. For now, the next research steps would involve testing the microwave power source and similar tests on the ground in a simulated lunar environment, including in vacuum. If some microwave dishes are something, smelling the resulting stuff might not be the best idea.
UCF – Methods of constructing lunar landing sites may involve microwave lunar soil
UT – What is the best way to build landing pads on the moon?
Subtitles – Lunar landers could spray landing pads immediately upon arrival on the moon
UT – NASA is investing in a plan to build landing pads and other structures on the moon out of regolith
Artist’s impression of a lunar base.
Credit – NASA