People could potentially live and work in lunar pits and caves with steady temperatures in the 60s
From: University of California - Los Angeles
July 26, 2022 -- Future
human explorers on the moon might have 99 problems but staying warm or cool
won't be one. A team led by planetary scientists at UCLA has discovered shady
locations within pits on the moon that always hover around a comfortable 63
degrees Fahrenheit.
The pits, and caves to
which they may lead, would make safer, more thermally stable base camps for
lunar exploration and long-term habitation than the rest of the moon's surface,
which heats up to 260 degrees during the day and drops to 280 degrees below
zero at night.
Pits were first
discovered on the moon in 2009, and since then, scientists have wondered if
they led to caves that could be explored or used as shelters. About 16 of the
more than 200 pits are probably collapsed lava tubes, said Tyler Horvath, a
UCLA doctoral student in planetary science, who led the new research. Two of
the most prominent pits have visible overhangs that clearly lead to some sort
of cave or void, and there is strong evidence that another's overhang may also
lead to a large cave.
Lava tubes, also found
on Earth, form when molten lava flows beneath a field of cooled lava or a crust
forms over a river of lava, leaving a long, hollow tunnel. If the ceiling of a
solidified lava tube collapses, it opens a pit that can lead into the rest of
the cavelike tube.
Horvath processed
images from the Diviner Lunar Radiometer Experiment -- a thermal camera and one
of six instruments on NASA's robotic Lunar Reconnaissance Orbiter -- to find
out if the temperature within the pits diverged from those on the surface.
Focusing on a roughly
cylindrical 100-meter-deep depression about the length and width of a football
field in an area of the moon known as the Mare Tranquillitatis, Horvath and his
colleagues used computer modeling to analyze the thermal properties of the rock
and lunar dust and to chart the pit's temperatures over a period of time.
The results, recently
published in the journal Geophysical Research Letters, revealed
that temperatures within the permanently shadowed reaches of the pit fluctuate
only slightly throughout the lunar day, remaining at around 63 degrees. If a
cave extends from the bottom of the pit, as images taken by the Lunar
Reconnaissance Orbiter Camera suggest, it too would have this relatively
comfortable temperature.
The research team,
which also included UCLA professor of planetary science David Paige and Paul
Hayne of the University of Colorado Boulder, believes the shadowing overhang is
responsible for the steady temperature, limiting how hot things get during the
day and preventing heat from radiating away at night. Meanwhile, the sunbaked
part of the pit floor hits daytime temperatures close to 300 degrees, some 40
degrees hotter than the moon's surface.
"Because the
Tranquillitatis pit is the closest to the lunar equator, the illuminated floor
at noon is probably the hottest place on the entire moon," said Horvath.
A day on the moon lasts
nearly 15 Earth days, during which the surface is constantly bombarded by
sunlight and is frequently hot enough to boil water. Unimaginably cold nights
also last about 15 Earth days. Inventing heating and cooling equipment that can
operate under these conditions and producing enough energy to power it nonstop
could prove an insurmountable barrier to lunar exploration or habitation. Solar
power -- NASA's most common form of power generation -- doesn't work at night,
after all. (NASA currently has no plans to establish an exploration base camp
or habitations on the moon.)
Building bases in the
shadowed parts of these pits allows scientists to focus on other challenges,
like growing food, providing oxygen for astronauts, gathering resources for
experiments and expanding the base. The pits or caves would also offer some
protection from cosmic rays, solar radiation and micrometeorites.
"Humans evolved
living in caves, and to caves we might return when we live on the moon,"
said Paige, who leads the Diviner Lunar Radiometer Experiment.
Diviner has been
mapping the moon continuously since 2009, producing NASA's second largest
planetary dataset and providing the most detailed and comprehensive thermal
measurements of any object in our solar system, including Earth. The team's
current work on lunar pits has improved data from the Diviner experiment.
"Because nobody
else had looked at things this small with Diviner, we found that it had a bit
of double vision, causing all of our maps to a be a bit blurry," said
Horvath. The team worked to align the many images taken by the instrument until
they could achieve an accurate thermal reading down to the level of single
pixel. This process yielded much higher resolution maps of the moon's surface.
Data from the early
stages of this lunar pit thermal modeling project were used to help develop the
thermal management system of the rover for NASA's proposed Moon Diver mission.
Horvath and Hayne were part of the science team for this mission, which aims to
have the rover rappel into the Tranquillitatis pit to research the layers of
lava flows seen in its walls and to explore any existing cave.
Horvath and Paige are
science team members for a new lunar-bound thermal camera led by Paul Hayne
named L-CIRiS, which will head to the lunar south pole in late 2023 to get the
first ground-based thermal images.
https://www.sciencedaily.com/releases/2022/07/220726160213.htm
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