In the coming years, NASA will be sending astronauts to the Moon for the first time since the Apollo Era. This time, and as part of the Artemis Program, NASA also plans to build the necessary infrastructure to establish a sustained human presence on the Moon and eventually missions to Mars – including the Artemis Base Camp and the orbiting Lunar Gateway.
They’ll be getting some new equipment, such as the exploration Extravehicular Mobility Unity (xEMU) spacesuit and a fancy new lunar lander. Of course, as the Artemis astronauts will also have to deal with the same hazards as their predecessors – not the least of which is lunar dust (or regolith). Luckily, NASA is investigating a possible solution in the form of a handheld electron/ultraviolet (UV) device that could mitigate this hazard.
Dr. Inseob Hahn, a program technologist and the project lead at NASA/JPL, described the device as a “Moon duster” and said it “will be like a typical duster spray on your desk, but it operates without air.” This technology could become a regular feature for future lunar missions, allowing astronauts to clean themselves off after conducting extravehicular activity (EVA) on the surface.
A Sticky Problem
As the Apollo astronauts learned, much of the lunar surface is covered in a thick sheet of fine powder, which is essentially the pulverized remains of moon rocks. Over the course of billions of years, the Earth-Moon system has been bombarded with meteorites, comets, and asteroids. Whereas Earth is protected by its thick atmosphere, which causes most of these objects to burn during entry (or lost most of their mass), the Moon has no such protection.
It also doesn’t have the atmospheric and geological activity Earth does, which erases the evidence of these impacts over time. For these reasons, the Moon’s surface has always been pockmarked, cratered, and covered with tiny shards of “moon dust.” To complicate matters, the lack of an atmosphere and magnetic field means that the lunar surface is constantly exposed to charged particles emanating from the Sun (aka. solar wind).
This causes the fine-grained silica to become electrostatically charged, which combined with its jagged nature, makes it especially sticky and abrasive. For the Apollo astronauts, this dust was a constant nuisance, sticking to spacesuits, optical lenses, thermal blankets, and equipment. It caused damage to spacesuits, got into the lunar lander, and technical problems and even respiratory issues for the astronauts themselves.
It was also highly resistant to cleaning efforts, with astronauts reporting that even vigorous brushing could not remove it. Nevertheless, NASA and other space agencies need to have mitigation measures in place if future plans for lunar exploration are to be successful. This is especially true since the Artemis Program calls for the creation of a “sustainable program of lunar exploration” – in other words, returning to the Moon to stay!
An Electrostatic Solution?
To date, NASA, the ESA, and other space agencies and research institutes have been testing various methods (using Apollo soil samples) for the mitigation of lunar regolith. This includes recent efforts on behalf of the ESA to develop new materials for spacesuits, for which they partnered with the French-developer Comex, the German Institutes for Textile and Fiber Research, and the Austrian Space Forum.
In addition, technologists from NASA’s Goddard Space Center – as part of the Dynamic Response of the Environments at Asteroids, the Moon, and moons of Mars (DREAM2) program – recently unveiled a new type of coating that could protect future rovers, landers, and other vehicles. This coating consists of atomic layers of titanium oxide that are applied directly to the dry pigments of paints using an advanced technique known as atomic layer deposition.
However, these methods are predictably expensive and require that complex design features be incorporated into all hardware destined for the lunar surface in the future. Fortunately, a team of researchers from NASA’s Jet Propulsion Laboratory (JPL) and the University of Colorado Boulder (UCB) has been working towards the realization of a non-contact, standalone system that would be handheld and portable.
The handheld device relies on a focused beam of electrons that would neutralize the electrostatic charge from regolith, allowing for its removal without imposing any restrictions on mission parameters. The technology is based on insights gained from previous studies of the natural electrostatic dust lofting process, which can happen on the surface of airless bodies, including the Moon and asteroids.
The way it works is simple, yet elegant. When an electron beam or UV field is applied to micro-cavities (which naturally form in a pile of dust) it causes a substantial negative charge to build on the surface of the dust particles. The repulsive force between these negatively charged particles eventually reaches the point where it causes them to eject them from the surface they were clinging to.
To test their concept, researchers at CU Boulder (led by Xu Wang) placed a lunar regolith simulant manufactured by NASA into a vacuum chamber. They then aimed the electron beam at a number of surfaces coated with these particles, including spacesuit fabric, glass, and solar panels. So far, the test results have been very encouraging, with an average of about 75-85% of the dust particles “jumping off” the surfaces, usually in just a few minutes.
The team is currently developing a testbed at NASA/JPL to evaluate how the technology would perform in the extreme cold of the lunar environment. Beyond that, the researchers are looking at various experimental methods to increase the cleaning efficiency of the electron beam. The faster it can remove dust, the more time astronauts will have for conducting vital research that can only be done on the Moon.
Given the cost-effectiveness that a handheld device would have versus advanced coatings and materials, it’s not hard to envision portable electron/UV devices integrated into future vehicles and habitats. Specifically, there could be cradles in the airlock where “Moon dusters” are placed to recharge between uses. Whenever crews return from an EVA, they could spend a few minutes “dust-busting” their suits and equipment before setting foot inside their habitat again.
This would not only significantly reduce the likelihood that dust will play havoc with mechanical devices and electronics. It will also be a windfall for astronaut health, as research has shown that exposure to regolith can lead to respiratory health problems (like bronchitis and lung cancer). Frankly, there are enough health hazards for astronauts without having to worry about inhaling jagged mineral particulates!
Further Reading: NASA