[HN Gopher] Lava Tubes on the Moon Maintain Comfortable Room Tem...
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       Lava Tubes on the Moon Maintain Comfortable Room Temperatures
       Inside
        
       Author : pseudolus
       Score  : 47 points
       Date   : 2022-07-31 12:02 UTC (3 days ago)
        
 (HTM) web link (www.universetoday.com)
 (TXT) w3m dump (www.universetoday.com)
        
       | edm0nd wrote:
       | TIL the moon has lava tubes whoa
       | 
       | https://en.wikipedia.org/wiki/Lunar_lava_tube
        
         | adastra22 wrote:
         | I mean we visited a collapsed lava tube on one of the Apollo
         | missions (15 I think?).
        
         | jrussino wrote:
         | There was recently a proposal to send rovers to explore them:
         | https://en.wikipedia.org/wiki/Moon_Diver_(spacecraft)
         | 
         | Check out the video on this page for a ton of details:
         | https://www.kiss.caltech.edu/lectures/2018_Moon_Diver.html
         | 
         | That particular mission concept was not funded, unfortunately,
         | but I'm hopeful that we'll do something like this soon. As
         | others in this thread have said, aside from just being really
         | cool these lava tubes on the moon (and Mars!
         | https://en.wikipedia.org/wiki/Martian_lava_tube) are an
         | interesting candidate for human habitats.
        
       | kemiller wrote:
       | Wait... so does this mean the moon really IS made of Swiss
       | cheese?
        
       | [deleted]
        
       | bell-cot wrote:
       | Issues:
       | 
       | Discovery - Other than spots where part of a lava tube's roof has
       | already collapsed, how quick & cheap is it to discover and map
       | the lava tubes under some non-trivial part of the lunar surface?
       | 
       | Scale - Let's say there's a lovely lava tube, X meters in
       | diameter and Y meters below the surface, in a location where we'd
       | like to build a moonbase. For a give size of moonbase, there will
       | be fairly narrow ranges of X and Y values where the lava tube is
       | actually suitable for housing the moonbase.
       | 
       | Cut & Fill Competition - Lava tubes aren't magical. If an area on
       | the moon has deep, stable "soil" (vs. near-surface bedrock)
       | containing ~few larger pieces of rock, then "dig a trench,
       | install tubular habitat, fill trench back in" may give a far
       | lower cost and/or higher predictability than "starting looking
       | for the perfect lava tube...".
       | 
       | Stability - If you're not familiar with the things that often go
       | wrong when humans start digging and building structures,
       | Practical Engineering (
       | https://www.youtube.com/channel/UCMOqf8ab-42UUQIdVoKwjlQ ) is a
       | pretty good intro. Note that we have a _lot_ of experience with
       | and data on how to do such things on the Earth. On the moon...not
       | so much. Some very painful and expensive lessons seem inevitable.
        
         | DennisP wrote:
         | > If the scientists' gravity analyses are correct, the lava
         | tube near Marius Hills could easily house a large U.S. city
         | such as Philadelphia
         | 
         | https://www.nbcnews.com/mach/science/gigantic-lava-tube-coul...
        
       | dr_dshiv wrote:
       | I can't wait until we set up base, blow up a large sporting arena
       | and get the moonball games televised! If everyone on earth wants
       | to watch something, then it can make money. And then, finally, we
       | have a financial incentive for moon infrastructure. Moon sports
       | ftw!
        
         | api wrote:
         | The moon is in general a better place than Mars for a first
         | attempt at a space settlement in part because there's more
         | options for monetization. It might not pay for the whole thing
         | but it would at least offset it a bit.
         | 
         | There are other big reasons too, like help being only days away
         | instead of months away in the event of a catastrophe.
         | 
         | Once we figure out how to do a space settlement on the moon,
         | then we could try Mars. Mars is likely a better long term home
         | for humans but it's about 60X as far away in terms of travel
         | time.
        
           | uncertainrhymes wrote:
           | If only we had some other long term home closer at hand.
        
       | chiph wrote:
       | I wanted to know how anyone could know this without having
       | actually measured it. They have modeled it using known
       | regolith/rock insulation values (presumably from the Apollo
       | samples).
       | 
       | > The researchers used computer modeling to analyze the thermal
       | properties of the rock and lunar dust and to chart the pit's
       | temperatures over a period of time.
       | 
       | I'm not sure I'd trust a lining applied to a naturally-formed
       | tube wall to retain air. But if we were to build our own tunnels
       | with a lunar TBM1, where we could control what the tunnel wall is
       | like, yeah, that'd be fine.
       | 
       | 1 https://en.wikipedia.org/wiki/Tunnel_boring_machine
        
         | nickff wrote:
         | The tunnels have been structurally stable for a long time,
         | sealing them seems much easier and more reliable than boring a
         | new tunnel, sealing it, and hoping it remains stable.
         | 
         | What kind of control do you think you'd have that would make
         | the 'artificial' tunnel better?
        
           | margalabargala wrote:
           | They've been structurally stable under a specific, unchanging
           | load for a very long time. If suddenly they are pressurized
           | to 1 atm, that may very well change.
        
           | vorpalhex wrote:
           | Preventing it from collapsing by increasing structural
           | durability seems wise.
        
             | nickff wrote:
             | The grandparent didn't say anything about reinforcing the
             | TBM-made tunnel, it just asserted that it would be
             | controlled. What techniques would be used for "increasing
             | structural durability" that are only applicable to TBM-made
             | tunnels?
        
               | aurizon wrote:
               | I would expect a lava tube from a drained lava flow to
               | vary greatly. We see many have collapsed over the ages.
               | It would provide an insulated underground tube miles in
               | potential extent. That said, the danger of a roof fall
               | would be low in some spots and ready to fall anytime in
               | others. This is still rock, about 6 tonnes earth mass per
               | cubic meter (one tonne on the moon). That means a very
               | strong tunnel liner is needed. It also needs to be air
               | tight. Research into the use of regolith as an ingredient
               | of a concrete needs to be done. One traditional concreted
               | mass is baking bricks of regolith. More research into
               | brick baking from various lunar materials is also needed.
               | A blown up fabric habitat would work inside this sealed
               | brick tunnel.
        
               | dylan604 wrote:
               | Can you do that without water? That would be the ultimate
               | so the little that is available doesn't have to be used
               | in construction materials
        
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