Moon Miners' Manifesto

#93 March 1996

MMM#93 Searching Mars for Lavatubes

Mars' vast shield volcanoes & lava sheets are prime territory for lurking lavatubes & prime real estate for the New Martians

  Whatever geological and scenic attractions may beckon siren-like to the first manned Mars expeditions, the "California" of future waves of Martian homesteaders is more likely to be the expectedly lavatube-riddled shield volcano flanks of Olympus, Arsia, Pavonis, Ascraeus, and Elysium - and likely similarly endowed vast lava sheets of the attendant Tharsis uplift region.

  The pre-excavated radiation shelter and the thermally buffered retreat of the tubes will make any settlement establishment much easier, giving it a considerable head start, as well as an enduring advantage. Mineralogical assets will also count, of course. And happily, the Tharsis region impinges on the head of the great Valles Marineris canyonland complex where many strata of rock will lay revealed for prospecting ease. Pavonis Mons, a great shield volcano already cited as possibly the most strategic mountain massif in the entire Solar System, its western flank the ideal site for a launch track complex, neighbors this canyonland head region on its eastern flank.

  But all this is little more than reasoned speculation. We do know what kind of terrain sports lavatubes on Earth and we do see analogous terrain on Mars. But that's it. On the Moon we have the added advantage of seeing actual examples of partially and wholly collapsed lavatubes (e.g. Hyginus and Hadley Rilles, respectively). Surveying such features on the ground will take generations. If we can search for them with orbiting instruments, our pre-settlement "treasure" maps of Mars will be enormously more helpful and propitious.

  While many, if not most tubes may lie within lava sheet layers that have been subsequently buried by later flows and thus be well below the surface, those in the uppermost flows should lie near enough to the surface to be detectable by appropriately tuned radar.

  Given our experience with the quixotic results of some of the Viking lander experiments, it only makes sense to fly such instruments first in low Earth orbit. We can then compare the findings with known "ground truth" and check the verisimilitude of the readings and better correct the calibration. Finding unsuspected tubes in various regions on Earth may be reward enough to merit such a precursor mission.

  This being done, a second such orbiter mission could do its tricks in orbit above the Moon, adding enormously to the practical knowledge necessary for intelligent planning of lunar development scenarios. The third tubefinder mission would head for Mars polar orbit. Lessons learned at Earth and at the Moon would allow mission planners to fly the leanest and lightest and least expensive probe to Mars capable of doing the job usefully well.

  Would permafrost deposits interfere with the readings and conclusions. Not likely, as the radar wavelengths for the former are LONGER - SHORTER by a factor of X. However the radar instrumentation needed for the two global searches would seem to make made-in-heaven bus mates - a "tundra and tube" mapper. If we did find permafrost and tubes in the same region, and we may not, that would mark the location as especially attractive for settlement development.

Lavatubes and their Uses:

On Earth, these features are typically a few tens of meters wide and high and hundreds to a few thousands of meters long. On the much less gravid Moon, and with the scale of Hadley Rille as evidence, we expect to find lavatubes hundreds of meters wide, and many tens of kilometers long. On Mars, with its in between 3/8ths normal gravity, we might expect such features to be in between in size, say 50- 100 meters wide and a few kilometers long. On both the Moon and Mars, "tubing" will be a major outdoor hobby, akin to limestone cave spelunking on Earth.

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