- 4504 - MAR'S OPEN PITS? - could shelter astronauts? - The pit craters possibly open into a larger cave that could provide a sheltered environment for both astronauts and hypothetical Martian life. A mysterious pit on the flank of an ancient volcano on Mars has generated excitement recently because of what it could reveal beneath the surface of the Red Planet.
--------------- 4504 - MAR'S OPEN PITS? - could shelter astronauts?
- The pit, which is only a few meters across,
was actually imaged on August 15, 2022 by NASA's Mars Reconnaissance Orbiter,
which was about 159 miles above the Martian surface at the time. This hole in
the ground is also not alone. It's one of many seen on the flanks of a trio of
large volcanoes in the Tharsis region of Mars.
-
- This particular pit is found on a lava flow
on the extinct volcano Arsia Mons, and appears to be a vertical shaft. That
raises a question: Is it just a narrow pit, or does it lead to a much larger
and remarkable cavern? Or, could it perhaps be a really deep lava tube formed
underground long ago when the volcano was still active?
-
- There are several reasons why pits and caves
on Mars are of interest. For one, they could provide shelter for astronauts in
the future; because Mars has a thin atmosphere and lacks a global magnetic
field, it cannot ward off radiation from space the way that Earth does.
Consequently, radiation exposure on the Martian surface averages between 40 and
50 times greater than on Earth.
-
- The other enticing aspect of these pits is
they might not just provide shelter for human astronauts; they could hold
astrobiological interest in the sense that they could have been sheltered
abodes for Martian life in the past, if microbial life indeed exists there.
-
- The presence of these so-called holes on the
flanks of volcanoes is a big clue that they are probably connected to volcanic
activity on Mars. Channels of lava can flow away from a volcano underground;
when the volcano grows extinct, the channel empties. That leaves behind a long,
underground tube. We see such tubes not only on Mars, but also on the moon and
on Earth.
-
- Sometimes, if the crust is thin enough, the
ceiling of these tubes collapses. If a collapse happens along the tube's entire
length, it forms a feature called a “rille”, which is a long trench commonly
found on the moon and sometimes in other areas of Mars.
-
- If the tube's ceiling just collapses in
small areas, however, we get pits like those imaged on Arsia Mons. Planetary
scientists have also seen pit chains on the flanks of Martian volcanoes, which
are linear stretches of multiple pits seemingly following the length of a lava
tube.
-
- How deep these pits descend is a
mystery. It remains uncertain whether
the pits open into a large cavern or whether they are contained to a small,
cylindrical depression. Some Martian pits have been imaged when the sun is high
enough in the sky to illuminate what appears to be the sides of the pit wall,
which implies they are shafts that go straight down into the flank of the
volcano. This would seem to suggest these pits are unlikely to open into larger
caves or tubes. -
-
- This would make them similar to pit craters
found on the volcanic mountains of Hawaii, which also don't open up to anything
larger and which are produced by the collapse of material deeper underground,
which causes material above to sink.
However, pits on the moon have been shown to have boulder-strewn floors
that appear as though they could lead to a larger subterranean volume.
-
- Pits can also be formed through tectonic
stresses that fracture a world's surface, and these may be less likely to lead
to a larger cavern. One other possible
explanation is that these pits open up into where underground rivers once
flowed billions of years ago.
-
- We can see a similar phenomenon on Earth,
in the form of a geological feature called a “karst”, which forms when
limestone bedrock dissolves and weakens, creating pits and sinkholes that open
up into areas of groundwater.
-
- If that is the case on Mars, then, if the
Red Planet ever once had life, those organisms may have sheltered in
karsts. Running water down the flank
of an active volcano would have been warm, providing the perfect protected
environment for life to flourish and stay safe.
-
- Still, this is all speculation for now.
We'll only have some concrete answers after future missions actually explore
some of these pits. Though a rover that drives to the edge of a pit would be
unable to descend, an airborne mission along the same lines as NASA's Ingenuity
helicopter, which operated on Mars for three years before it became grounded in
January 2024 after damaging one of its rotor blades, would have the ability to
hover over and descend into a pit to see what is down there.
-
- If these pits do open up into caves, they
may become a preferred landing site for future crewed missions to Mars that
will require astronauts to build a sheltered basecamp away from the world's
unrelenting radiation.
-
-
June 20, 2024 MAR'S
OPEN PITS? -
could shelter astronauts?
4504
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