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Background: While watching SSERVI Director’s Seminar Series: RIS4E (Science and Exploration of the Moon, Near Earth Asteroids, the Moons of Mars enabled by the Remote In Situ and Synchrotron Studies for Science and Exploration), more info here, speaker Tim Glotch mentioned (roughly 26 minutes into the presentation) that they used kites and might use drones in the future to perform LiDAR scans of pits and otherwise untraversable terrain during their simulated lunar analog environment tests at Hawaii.

Obviously, as also mentioned by Tim Glotch in presentation, kites and conventionally propelled drones using aerodynamic lift wouldn't work on the Moon since there's no atmospheric pressure to speak of, but this got me thinking that future foot on the ground activities on the Moon might use some way of hovering communications and science equipment higher above ground level, say to support various in situ ground operations and communicate with a distant or obstructed from direct line of sight base. One idea I had could be a type of a suction tube that collects surface dust at its head end touching the ground, sucking dust towards its tail end, where the exhaust is redirected towards the ground to achieve thrust and enable it to hover at some distance to the ground. Wild? Perhaps, but similar works here on the Earth at six times the gravity too by using jets of water to propel aquatic hoverboards. Add a spatially aware controller software, a few high precision accelerometers and a gimballed nozzle to the mix, and you get an autonomously hovering structure that could suspend communications antennae and/or remote sensing equipment above the lunar ground by the pressure of its dust, and be portable and easily erectable / collapsible wherever needed.

To the question: Wild ideas aside (and yes, there are a few other problems with it I didn't yet manage to address like that it would stir a lot of dust unless it's a highly efficient and precise recycler / rebreather system), one thing I'm rather unsure of is how does one design the suction head so it starts working in a nearly no atmospheric pressure environment and with no surface tension to speak of? And once such a system would start, would the lunar dust itself, now hopefully an aerosol inside the tube, provide sufficient surface tension, or would it clog the suction tube if no additional gas is continuously supplied to such a system and mixed with the dust intake?

For what is worth, this is not only relevant to my imagination gone wild, but will surely have to be addressed to run, say, mass separation systems for lunar regolith ISRU (In Situ Resource Utilisation), removal of sharp silicate dust from breathable air environments, and if this works out well enough, perhaps even hovercraft as means of (safe and durable) transport on the sharp and abrasive lunar regolith surface.

Has any research institute, groups or inventive individuals published papers or patents on designing industrial continuous suction systems for use in exospheric conditions, preferably with tests done on lunar regolith simulant, and what were their conclusions / results?

What is the lunar dust analog to additionally supplied gas mass ratio that could start and sustain suction and what is the expected durability and most frequent failure points of such equipment? Also, has anything like it, on a smaller scale, perhaps been done / tested by any of the Apollo missions?


TL;DR - Yes, I'm basically asking how does one design a vacuum cleaner that would work in vacuum. Well, kinda. Read the question. :)

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    $\begingroup$ Time to find out how to use static electricity to attract & collect dust. $\endgroup$ – Deer Hunter Oct 8 '14 at 3:12
  • $\begingroup$ @DeerHunter Yup, that was something I already considered, but it might as well prove more of a hindrance (topmost surface would be electrostatic already, but triboelectricity could result in catastrophic discharge) rather than help. I can't think of a simple way of designing around that, but sure, if it's an answer to my question, I'd accept it. ;) $\endgroup$ – TildalWave Oct 8 '14 at 3:15
  • $\begingroup$ Could benefit from an illustration of an aquatic hoverboard (in the Sports Illustrated swimsuit style, perhaps) $\endgroup$ – Deer Hunter Oct 8 '14 at 3:16
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    $\begingroup$ @DeerHunter Best I could find: pbs.twimg.com/profile_images/471793400425893888/eUWfUeCb.png :) $\endgroup$ – TildalWave Oct 8 '14 at 3:20
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    $\begingroup$ The only thing I know of is the OSIRIS-Rex TAGSAM, which requires expending a consumable, nitrogen gas, to move the regolith. $\endgroup$ – Mark Adler Oct 8 '14 at 6:00
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Have a look at this paper, which discusses using magnets to collect the regolith in tubes similar to a maglev system. It also claims that the very fine dust particles can remain electrostatically suspended above the surface, forming an abrasive pseudo-atmosphere. The lunar hoverboard would not be very popular with your fellow lunar residents.

Fortunately it seems to be easily meltable with microwaves. So roadbuilding might be as simple as a bulldozer followed by a downward-pointing magnetron.

Additionally, if I wanted a liquid-phase seal that I could feed incoming material through without having to cycle an airlock, I'd consider a column of mercury in a "U" shape. You will eventually lose mercury to vapor evaporation on the vacuum side, but very slowly.

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You cannot vacuum in a vacuum, if you want to use a pressure differential to move dust on the moon you will have to supply the gas yourself so it's no longer a vacuum. You could set up a system which releases gas which is then sucked up, however I doubt it's a viable proposition because you won't be able to match the vacuum power of space itself. Having the gas in the first place is a big problem.

One possible solution would be to build some sort of structure which when set down and anchored to a flat enough part of the lunar surface would be able to create a seal strong enough for partial atmospheric pressure to be established. Once atmosphere is pumped in you can then vacuum and collect the dust, then pump the atmosphere back out again.

This seems overly complicated and has many challenges compared to simply creating an efficient scooping mechanism.

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  • $\begingroup$ But did you see the link Mark Adler gave in a comment above? OSIRIS-Rex will "blow" dust into a filter. $\endgroup$ – LocalFluff Oct 8 '14 at 11:49
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    $\begingroup$ If you are an unanchored probe on a low-gravity body and all you want to do is collect a small amount of dust then blowing it into a filter makes sense. If you want economic, large scale regolith collection on the moon then it's not the best choice. $\endgroup$ – GdD Oct 8 '14 at 12:08

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