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I've been mulling over a thought for quite some time now. As we gear up for a return to the Moon and possibly Mars, I can't help but think about one of the major issues from the Apollo missions: the pervasive and abrasive nature of moon dust, which affected everything from spacesuits to machinery.

I'm interested in the advancements over the past 50 years that aim to tackle this issue. Does anyone know of a solid long-term solution for managing moon dust, especially if we plan on mining on the Moon? I've seen concepts involving suits attached to the outside of vehicles and habitats, but it seems it would only be a matter of time before those suits need to be fully replaced due to abrasive dust.

Alternatively, I fear that humanity might end up confined to directing robots from an office, which certainly isn't the vision of space exploration we were promised.

Looking forward to your insights and discussion!

Thanks,

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I am a big proponent of simply washing the suits regularly. This was infeasible during Apollo, because of mass limitations, however, with the dawn of Starship and potential ISRU water, using a bunch of water to hose down the astronauts before they take off their suits is completely valid. Just have the airlock function like the inside of an industrial dishwasher.

Besides hosing down the astronauts, there are also concepts for "liquid airlocks" which would require the astronauts to fully submerge themselves in order to enter the habitat. This alone might clean off lots of the dust, but engineers could also use this as an ultrasonic bath which is excellent at removing dust and debris from objects. These have some issues like boil-off, but I think these are easily solvable with a lid or even a thin oil-like substance that coats the surface of the liquid which is exposed to vacuum to stop it from evaporating. In general, I think these are really cool, and could even be used as vehicle-entry into bases without needing to constantly pump atmosphere into and out of airlocks.

From a maintenance or life-cycle engineering perspective, regularly cleaning the suits of abrasive dust before it becomes a problem is an obvious approach. Most mechanical wear processes aren't linear, but rather rapidly reach a steady state and then eventually "suddenly" break down very rapidly. If you have, for example, a shielded bearing and you replace the shield before it fails and dust gets into the rolling elements, all it costs is a little plastic disk instead of a whole expensive bearing. I think that with regular cleaning and the replacement of wear components and certain "sacrificial" parts, moon dust could be effectively handled.

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    $\begingroup$ I have thought a vacuum airlock would be good after getting to go on a tour of the JSC meteorite sample lab, I remember besides wearing bunny suits we each stepped briefly into what was basically a vacuum shower with air blowing on us. I realize lunar regolith needs more than that, but I can imagine it including vacuum hoses with brushes that the astronauts would use on themselves and each other in the airlock. But I had not heard of or thought of the liquid idea which sounds much more thorough. Maybe not on the early missions but for sure later. $\endgroup$ May 3 at 22:30
  • $\begingroup$ Thank you all for the thoughtful reply. The concept of a liquid airlock is particularly novel and exciting to me. It really sparks the imagination! Regarding the idea of having a thin, oil-like layer on top of the liquid to prevent evaporation, I have some concerns, and I am sure there is an obvious solution. Could this oil potentially cause issues by allowing dust to adhere to the outside of the suits? This could be problematic, especially considering the various equipment astronauts handle and use on a daily basis. Thank you again so much for your answers! $\endgroup$
    – Twicks
    May 11 at 17:39
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We won't know if we are "there yet" until new suit designs are tried out on the Moon. The problem is certainly being worked on. Check the links below.

Moon dust is abrasive, which causes wear on parts moving in relation to each other. Movement is required for functional utility of a suit.

The big design problem with pressure suit design is change in volume with joint movement. If any volume change occurs, energy is needed to return to the neutral position (pressure x volume = work). To meet this requirement of constant volume, two types of constant volume joints have traditionally been employed: Bearing Seals and Bellows.

Below is the torso section of the Extravehicular Mobility Unit (EMU) suit which makes extensive use of bearing joints:

enter image description here enter image description here https://ingeniumcanada.org/aviation/education/space-suit-hero-upper-torso-assembly

The seals and bearings are complex, and a major source of suit leakage, even without moon dust gritting things up.

enter image description here

The alternative design is the bellows joint which allows flexion but not rotation. This elbow bellows is combined with bearing seals at each end to permit rotation. enter image description here

An Investigation on the Configuration of Spacesuit Soft Joints International Conference on Civil, Materials and Environmental Sciences (CMES 2015) IOP Conf. Series: Materials Science and Engineering 187 (2017) 012014 doi:10.1088/1757-899X/187/1/012014

A bellows joint works on the same principle as a vacuum cleaner hose: Circumferential bands prevent change in diameter while soft sections in between allow flexion. A longitudinal restrainer is required to prevent internal pressure of an EVA suit from ballooning the length of the bellows. This restrainer defines the axis of permissible flexion. Bellow joints are very dust resistant. However, because they cannot rotate, they need to be paired with bearing seals.

Without these constant-volume joints, suit pressure would immobilize the astronaut. Unfortunately, bearing joints (with their seals) are a necessary evil. With their tight tolerances and rubber seals, they are very susceptible to abrasion from regolith dust. And efforts to blow dust out risks driving it deeper into crevices.

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My former colleague Kristen John has a presentation on dust problems and mitigations on ntrs: Survive the Dust: Dust Mitigation Technology to Enable Survive the Night Capabilities

enter image description here

(The presentation is not specifically about suits but dust issues in general)

Examples of approaches mentioned in the presentation:

  • Low energy surface coatings to make the dust easier to remove

  • Blowing dust off with compressed gas

  • Electrostatic precipitation (for internal gas flows)

  • Electrodynamic dust shields:

high voltage pulses will 'walk' particles from surfaces

  • Use of Dust Tolerant Mechanisms
  • Develop a Lunar Dust Sensor

The presentation includes a list of resources and is a useful introduction to semi-current (2022) NASA approaches to the topic.

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