Instead of a big huge lava tube, perhaps what's needed in the early period is a reasonable-sized cave. What would be the ideal volume for an early underground lunar station? Probably no more than several thousand cubic meters at most?Besides the lava tubes, are there any other processes on the Moon that could have created caves - perhaps smaller ones?Here's a good article by Paul Spudis:https://www.airspacemag.com/daily-planet/cave-living-moon-180961494/QuoteBut lava tubes are found only in the maria, which are mostly concentrated near the equator and at low latitudes. One of the biggest drawbacks to cave living on the Moon is that we don’t have any near the poles. At the poles there is near-constant sunlight, along with deposits of water ice—valuable resources essential for human habitation. Yet enjoying the advantages of underground living doesn’t require caves. It is possible to place a habitat at the bottom of a deep crater, lay out an airlock, access tunnels, electrical cables and cooling lines, and then backfill (cover over) the crater with lunar regolith (soil) using a bulldozer. This simple construction technique provides all the thermal and protection advantages of cave dwelling, without restricting the outpost location to a less than optimum locality.The advantages of cave life seem so attractive that every time a new lunar lava tube discovery is made, there is a call to use them to live on the Moon or other planets (most recently shown in the current “Mars” television mini-series). But people live where they can make their livelihoods and on the Moon, that “pay dirt” is at the poles, in the form of water and electrical power. The Willie Sutton principle still prevails.
But lava tubes are found only in the maria, which are mostly concentrated near the equator and at low latitudes. One of the biggest drawbacks to cave living on the Moon is that we don’t have any near the poles. At the poles there is near-constant sunlight, along with deposits of water ice—valuable resources essential for human habitation. Yet enjoying the advantages of underground living doesn’t require caves. It is possible to place a habitat at the bottom of a deep crater, lay out an airlock, access tunnels, electrical cables and cooling lines, and then backfill (cover over) the crater with lunar regolith (soil) using a bulldozer. This simple construction technique provides all the thermal and protection advantages of cave dwelling, without restricting the outpost location to a less than optimum locality.The advantages of cave life seem so attractive that every time a new lunar lava tube discovery is made, there is a call to use them to live on the Moon or other planets (most recently shown in the current “Mars” television mini-series). But people live where they can make their livelihoods and on the Moon, that “pay dirt” is at the poles, in the form of water and electrical power. The Willie Sutton principle still prevails.
There are several exciting items about lava tubes.1) they may contain frozen volatile like water2) less time to clear and setup for use. It takes a significant amount of time to bore a tunnel. The Lava tube comes complete with a probably pre-sealed and structurally significant material already on the walls of the tube. No mining or processing needed just heat and reform into a solid glass surface.3) possible cache of high concentrations of other low % existing in total minerals on the Moon such as Carbon.Problem is until something goes in and takes a look and samples, the answers about what could be there is only speculation.As Spudis says initially Poles are easier to set up an initial Base. Later with significant high speed electrically powered ground transportation (such as a HyperLoop), having large cities anywhere on the surface no longer becomes tied to where there is constant sunlight and abundance of water. Cheap transport of bulk material (including water) around on the surface with L1 and L2 based SPS 24/7 power the initial limitations favoring the Poles disappear.
Quote from: redliox on 10/21/2017 02:10 pmI believe the lava tubes, like at Marius Hills, definitely should be investigated.How could a probe explore a skylight like one of these?Google found this:https://www.nasa.gov/pdf/637136main_Whittaker_Presentation.pdfThe rappel example is how I imagined it.Random thought: I wonder if the ice at the poles could also create caves or at least overhangs. I think the lunar poles have moved over time so you could imagine a situation of different layers with different amounts of ice. Or perhaps an impact within or at the edge of a crater laying magma over icy ground that disappears out from under the much stronger roof.
I believe the lava tubes, like at Marius Hills, definitely should be investigated.How could a probe explore a skylight like one of these?
A new site may have been found near the North Lunar Pole at Philolaus Crater. It also has the advantage of being on the Near Side.
I am happy to accept the interpretation that these may be skylight openings into voids, but I am not keen on the interpretation that the void is a lava tube. This is the floor of an impact crater, where impact melt would be expected, and there is no sign of basalt flows which might include lava tubes. The network of fractures in the crater floor is similar to many found in other melt areas. I would be happier if this story only talked about voids and fractures but did not mention lava tubes. In fact I got the impression from Pascal's talk that he had probably had some criticism about the mention of lava tubes, and was trying to backpedal a bit on it.
Quote from: oldAtlas_Eguy on 10/23/2017 05:52 pmThere are several exciting items about lava tubes.1) they may contain frozen volatile like water2) less time to clear and setup for use. It takes a significant amount of time to bore a tunnel. The Lava tube comes complete with a probably pre-sealed and structurally significant material already on the walls of the tube. No mining or processing needed just heat and reform into a solid glass surface.3) possible cache of high concentrations of other low % existing in total minerals on the Moon such as Carbon.Problem is until something goes in and takes a look and samples, the answers about what could be there is only speculation.As Spudis says initially Poles are easier to set up an initial Base. Later with significant high speed electrically powered ground transportation (such as a HyperLoop), having large cities anywhere on the surface no longer becomes tied to where there is constant sunlight and abundance of water. Cheap transport of bulk material (including water) around on the surface with L1 and L2 based SPS 24/7 power the initial limitations favoring the Poles disappear.By time we are ready for large lunar colonies, running 2500km buried water pipe from poles to lava cave shouldn't be a big under taking. Pipe doesn't need to be huge only need a few 1000 cubic meters of water a year for launch and top recycled life support water. Power would be beamed from Space Solar Satellites, building these for earth may well be colonies main business.