FEATURE
Taking on Moondust
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NASA has ranked lunar dust as among the top hazards to mitigate before sending humans to the Moon for extended stays — and for good reason. Barbed and electro-statically charged, these ultra-tiny dust particles cling to everything, much like Styrofoam peanuts used for packing. They can gum up machinery, damage space suits, and worse, find their way into astronauts’ living quarters, which could cause long-term health problems for inhabitants. For the past couple years, Goddard’s Internal Research and Development (IRAD) program has funded innovative ideas aimed at understanding the physics that create the dusty environment and finding ways to mitigate it. Below are a few of those technologies.
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Mimicking the Self-Cleaning Lotus Plant
The lotus plant has inspired one Goddard aerospace engineer to develop a special coating that would mimic the plant’s unusual self-cleaning properties and help prevent the Moon’s powdery grit from accumulating on astronauts and their gear.
Wanda Peters is working with an Atlanta-based company, nGimat, to determine whether the two “lotus coatings” that the company has developed in collaboration with Georgia Tech would work on the lunar surface.
The lotus plant, which lives along muddy waterways in Asia, is well known for its ultra-hydrophobic nature. Despite living in muddy conditions, the plant’s leaves and flowers remain clean because they are composed of micron- and nano-scale structures that prevent dirt and water from adhering. Water droplets literally roll off, taking mud and tiny insects with them.
Widespread Application
The ability to replicate these properties could prove invaluable to NASA, says Peters, who heads Goddard’s Coatings Engineering Group. The Agency could coat spacesuits, radiators, solar arrays, and other equipment with the material to repel dust and prevent it from accumulating. “The question we need to answer is whether we can really get a lotus coating to work in real life.”
So far, environmental test results on nGimat’s two formulations are promising. Both have maintained their particle-shedding properties even when exposed to harsh ultraviolet light and other space-like conditions. However, she and her team have had trouble consistently reproducing the formulas. Consequently, Peters said she is considering developing her own coating in parallel with her current research.
Although she has high hopes for eventually producing a space-qualified lotus coating, she concedes that it’s only one of several strategies NASA will need to employ to make living and working on the Moon tolerable. Some super-fine dust particles still will find their way into astronauts’ living quarters. Consequently, Peters also is looking at other cleaning technologies, including air showers and vibration, to repel dust.
“Habitation areas on the Moon will be like any house. They will get dusty,” she says. But given the environmental hazards posed by Moondust, “we’ll need to minimize it as much as possible.”
### How to Solve the Lunar Dust Problem: Pave the Surface
Goddard technologist Eric Cardiff offers an unusual solution to help diminish the dust dilemma on the Moon: pave the area around a lunar base using nothing more than focused sunlight.
Cardiff is developing a prototype of a four-wheeled vehicle that would use a lens to focus sunlight onto the lunar surface. The sunlight-generated heat would melt or sinter the dust to create a hardened surface.
The current design employs a Fresnel lens, a very lightweight optic that bends light the same way as a normal lens, but takes up significantly less mass. For operations at NASA’s proposed polar base near Shackleton Crater, the so-called Dust Mitigation Vehicle (DMV) also would need a primary mirror to reflect the sunlight from the near-horizontal angle of the Sun onto the Fresnel lens.
Inspired by a Previous IRAD Investigation
Cardiff conceived the idea while working on an earlier IRAD-funded technique called vacuum pyrolysis to extract oxygen from the lunar soil. That early concept also made use of a Fresnel lens, which concentrated sunlight before it passed through a window and into a vacuum chamber where the light ultimately heated and melted the regolith, releasing small amounts of oxygen. From his research, he discovered that lunar soil melted at relatively low temperatures, giving birth to the possible dust-mitigation strategy.
Cardiff admits that the idea of melting dust isn’t new. A University of Tennessee professor has been working on similar applications using microwave-heating techniques. However, the professor’s concept would require substantially more power, which means that his device would have to be tethered to a power source or would have to carry very large and heavy solar panels. Cardiff also says that the technique isn’t as efficient. Only half of the energy put into the microwave emitters is released as microwave radiation, which means that the vehicles would have to carry large radiators for the “waste heat.”
The advantage of DMV, he says, is that it’s lightweight (less than 110 lbs. or 50 kg), requires little power, and could even be used as a science platform. As the top layers melted, the DMV could measure the regolith’s physical properties as well as its embedded gases.
The DMV was built as a remote-controlled prototype. It is being tested at the Goddard Propulsion Test Site over simulated lunar dust to see how fast the DMV can really work.
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