Study: Lava tubes on Mars and the Moon will be gigantic

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A new study comparing lava tubes on the Earth with those detected from orbit on Mars and the Moon now suggests that tubes on those other worlds will be many times larger than on Earth.

Researchers found that Martian and lunar tubes are respectively 100 and 1,000 times wider than those on Earth, which typically have a diameter of 10 to 30 meters. Lower gravity and its effect on volcanism explain these outstanding dimensions (with total volumes exceeding 1 billion of cubic meters on the Moon).

Riccardo Pozzobon adds: “Tubes as wide as these can be longer than 40 kilometres, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes. The latter are so big they can contain Padua’s entire city centre”.

Moreover, the data suggests their roofs, even at this size, will be very stable because of the lower gravity, making them excellent locations for large human colonies.

The researchers also suggest that there are many intact such lava tubes under the mare regions on the Moon, their existence only hinted at by the rare skylights created due to asteroid impact.


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  • Jerry Greenwood

    “The latter are so big they can contain Padua’s entire city centre”.

    I see Wales and 747s have a new size comparison standard to compete with.
    I was just getting my head wrapped around the old standard when the scientific community changes it.?

  • Nitecat

    I wonder if there are any located fairly close to the recently located water deposits. High speed mag – lev trains to carry the processed and purified water to the tube city ! I’m flashin’ back to Neil P. Ruzic’s ” where the winds sleep ” and Heinlein’s ” the moon is a harsh mistress ” . Lets do it !

  • LocalFluff

    @Nitecat What I’ve heard from geologists, is that lava tubes are actually uninteresting from a resource utilization point of view. They are dressed in boring useless basalt. But as you say, some might be near more interesting areas, such as frozen water ice caps now underground, that formed billions of years after the last volcanic activity that dug lava tubes.

    I wonder if there are huge lava tubes in the Olympus Mons structure. Great kilometer towering halls still secluded with captured gasses from the underworld. Such to make Satan thrive in it, as once under Iceland. Some spelunking adventure waiting for Bob there!

  • Tom Billings

    This is why the next step in Lunar Settlement should be a Ground-Penetrating Radar in orbit around the Moon. It should have a wavelength long enough to penetrate around 2 kilometers at an attainable power level, and a synthetic aperture system for high resolution, on the order of 1-10 meters. Probably, while it should have a minimum altitude of around 10 kilometers, its maximum altitude should be many times greater, to allow time for an ion engine propulsion system to correct the system’s orbit after each low pass near the Moon’s “Mascons”, which would otherwise quickly cause it to crash into the Moon’s surface.

    The lava tubes would initially shield people well from radiation on the surface, as well as temperature variations and the ever-present erosive dust of the surface, even when their habitat is only and inflatable brought from Earth. The resources of the surface regolith can be used to make more habitats once the raw materials are refined and placed into the lava tubes themselves. Once the highly ferrous nature of basaltic terrain is exploited to produce Iron and Nickel powders, that can be used to create a seal for sections of lava tube in which pressure can be brought up to Earth norms.

  • Tom Billings

    LocalFluff said:

    “What I’ve heard from geologists, is that lava tubes are actually uninteresting from a resource utilization point of view. They are dressed in boring useless basalt.”

    Find new geologists!

    Basalt has Oxygen! It has Iron, and Aluminum as well. What’s more, the basaltic regolith fines on the surface have about .1-.8 % of Native Nickel/Iron particles, from the re-condensation of impacted nickel/Iron meteoroids. Each of these is a useful construction material under the right design principles, in a number of different combinations.

    If you’re doing nothing more than treasure hunting, those are boring. If you are settling the Moon, they are the backbone of the colony!

  • Note also the environmental advantages of establishing your colony in an underground lava tube: no big temperate swings to deal with, protection from radiation, and you already have a standing structure you can use to seal for habitation.

  • John Hare

    Even if some desired resource is 1,000 km from the mine to the city, it’s about an hour commute in a vacuum mag-lev.

  • Alex Andrite

    All the better to hide the Locals during the day.

  • Brad

    That’s fascinating.

    If humans were to exploit any of these lunar lava tubes, it most likely would be those with apparent skylights, right? Lava tubes with skylights are easiest to find and provide easy surface access.

    So here is my big question: would a lunar lava tube with a skylight, serve as a cold trap that could accumulate lunar ice over the course of hundreds of millions of years?

    Could we be that lucky?

  • LocalFluff

    Ground penetrating radars are so important now. The probes now sampling Ryugu and Bennu should’ve been equipped with it! The cohesion of asteroids, and for example Phobos, is still poorly understood. It is fundamental for understanding how planets formed in the first place. But I think it’s coming. Both Chinese Lunar rovers had ground penetrating radars, as does the Martian Perseverance rover (a Norwegian radar, though, so we’ll see how that works out… I’m suspicious of the quality of anything dry that my neighboring people does.)

    @Tom But oxygen and iron and magnesium and titanium is to be found everywhere on the Moon, and are better where there’s sunlight to process it. The value of Lunar lava tubes is in their structure and environment rather than their material resources.
    There are some cool ideas around on how to explore them with rovers:

    @Brad Indeed they are cold traps. But water on the surface of the Moon is formed by the Solar wind protons marrying with oxygen in the rocks. And because lava tunes are closed from Sun beams, water should only form under skylight openings.

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