MMM Classics Year 10: MMM #s 91-100 - Moon Society

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.
CHRISTEN THESE TWO PROPOSED MISSIONS:
MMM invites readers to propose (a) name(s) for
our proposed Mars Permafrost Orbital Mapper and
Mars Lavatube Orbital Mapper. The name can be
drawn from mythology, literature, or history, or consist
of an appropriate acronym.
This not an idle exercise. Chapter space activists
were responsible for christening “Lunar Prospector”
in ‘89, a name which stuck through several deaths and
rebirths.
by Peter Kokh
PER•ma•frost: [from perma(nent) + frost] perennially
frozen subsoil. Also called pergelisol.
Where do we find permafrost (on Earth)?
We find permafrost mostly in circum arctic lands of
Alaska, Canada (Northwest Territories, northern Quebec,
northern Labrador), Greenland, Iceland, Scandinavia (Norway,
especially), and Russia-Siberia. Permafrost is the soil condition
that manifests itself in “tundra” type no-root or shallow-root
vegetation.
[loc. cit.: Permafrost can be differentiated into 3 main zones: (a)
continuous permafrost, where very little land is unfrozen and
where permafrost may reach depths over 600 meters or 2,000 feet;
(b) discontinuous permafrost, where patches of unfrozen ground
occur; and (c) sporadic permafrost, where patches of permafrost
occur in a generally unfrozen area. Overlying the permafrost is an
‘active’ layer of rock or soil which thaws in summer and freezes in
winter.]
How does permafrost form?
Permafrost forms in ground water areas through
gradual transition to ever more severe winters and ever shorter
and cooler summers. The deeper the ground water penetrates,
and the greater the water content per volume of soil, the thicker
and richer the permafrost layer.
Why do we think there may be extensive permafrost
deposits on Mars?
There is abundant evidence from high resolution
Viking photos of landforms for which the only plausible
explanation is that they were formed by water: tear drop shaped
islands in the middle of large valleys, relic beaches and ancient
Moon Miners’ Manifesto Classics - Year 10 - Republished January 2006 - Page 29