Tunnels on the moon

I recently read some interesting stuff on the prospects of using lava tubes on the moon to house a moon base.

Lava tube are left over from volcanic activity. They are self contained spaces in volcanic rock, found anywhere from a few meters under the surface, to a few thousand.

On Earth, these tubes are typically a few meters high. On the moon, they are likely to be ten times the size (none have been found yet, but i'm not sure any have been looked for).

If one of these tubes could be made air tight, and structurally sound, it could be an excellent basis for a lunar outpost. If a tube were found, say, ten meters beflow the surface, it would most likely be structurally strong enough to withstand a little light engineering, and could be propped up with steels imported from Earth (expensive), bricks made from the lunar regolith (difficult, and if you can build them, you're half way to not needing the lava tube) or perhaps an inflatable structure.

Some sort of spraying robot could then traverse the length of the tube, spraying the walls with plastic, or preferably a cement made from local regolith to make it air tight.

Ironically, the larger size of lunar lava tubes would make this exercise much more difficult, in terms of spraying, and keeping the tube at a reasonable temperature (note to self: check ambient temperature of lunar surface ).

The first such base, therefore, would want to be perhaps, five meters tall and ten meters long. The floor could be levelled with an inflatable pontoon, and fixtures bolted into the wall.

Larger tubes would have their advantages, though. Under artificial light, a garden would make the living space much more palatable, not to mention the benefits of a small farm, even a smelt and a factory.

Lava tubes might be used within a few years build up of resources on the moon.