- 4559 - MOON CAVES - need to be explored? - Lunar orbiting satellites first spotted pits on the moon's surface decades ago. Many of these were thought to be openings that connected to substantial underground tunnels that form through volcanic processes, but only now has this been confirmed through the analysis of radar data.
------------------------- 4559
- MOON CAVES
- need to be explored?
-
- Moon caves tell us about the shared origins
of the Earth and the moon. The pit in
“Mare Tranquillitatis” leads to an underground cave system. Using radar, a Nasa
spacecraft, “Lunar Reconnaissance Orbiter” (LRO), has confirmed the existence
of caves beneath the lunar surface.
-
- Some of the tunnels thought to exist on the
moon are expected to be lava tubes, which are also found on Earth. When molten
lava flows out of the ground, the lava stream eventually cools and hardens into
a crust. The lava inside is still molten, and continues to flow. Once the lava
has flowed away, it leaves an empty tunnel called a lava tube. These formation
processes are thought to be very similar on the Earth and the moon.
-
- Radar (electromagnetic waves of 12.6cm
wavelength) fired at acute angles towards these lunar pits, partially
illuminated the shadowed subterranean areas to generate measurable radar echo
signals. The timing and amplitude of the
reflected signals allowed researchers to compare with simulations and build up
a picture of the underground terrain. Data indicate that the largest "Mare
Tranquillitatis" pit leads to a cave 80 meters long and 45 meters wide: an
area equivalent to around half a football field..
-
- It is likely that the lunar surface is home
to hundreds of such caves. It is widely thought that around 4.5 billion years
ago, a young Earth violently collided with a Mars-sized proto-planet, splitting
our youthful planet into the Earth and moon system we have today.
-
- After this high energy impact, the moon may
have become molten. It is therefore hardly surprising that caves of seemingly
volcanic origin, bearing striking similarities with volcanic caves here on
Earth, are present on the moon. Volcanic
activity on the moon petered out about entirely around 50 million years ago.
-
- On Earth, we live in an unusually lucky
environment, which protects us from threats from outer space. For example,
Jupiter, the largest planet in our solar system, is well placed to
gravitationally drag asteroids away from Earth. This minimizes the frequency of
cataclysmic asteroid collisions with our planet, such as the one that spelled
the end of the dinosaurs.
-
- One less obvious threat to life on Earth is
ionizing radiation. The whole solar system is constantly bathed in a soup of
charged particles called galactic cosmic rays, which are accelerated to huge
speeds by distant supernova explosions, sending them on a collision course with
Earth.
-
- In addition, periodic events called coronal
mass ejections from our own sun fling highly energetic particles in our
direction in much larger numbers, but on a less frequent basis. The Earth's magnetic field protects us from
this radiation to a large degree, by funneling the charged particles towards
the north and south poles.
-
- This is the origin of “aurora borealis”
and “australis” that light up the night sky at high latitudes. The Earth's
thick atmosphere also protects us, but we still get some exposure: a return
transatlantic flight, where we are higher up in the atmosphere, gives the
traveler a dose of radiation equivalent to five X-ray scans.
-
- Now spare a thought for our moon, which
possesses neither an atmosphere nor a notable magnetic field. Far from being a
"sea of tranquility" (the name of the site of the first human landing
on the moon in 1969), the lunar surface is constantly bombarded by high-energy
radiation.
-
- This poses a serious challenge for
populating a moon base with humans. Astronauts bouncing about on the lunar
surface will soak up about 10 times more radiation than experienced on a
transatlantic flight and about 200 times what we get on Earth's surface.
-
- Although our bodies can deal with the
generally harmless low levels of background radiation we experience on Earth,
exposure to high levels of ionizing radiation can have serious health
implications. When ionizing radiation interacts with the body, it can ionize
the atoms contained within cells, stripping them of electrons. This damage can
sometimes prevent DNA from replicating properly, and in extreme cases, can
cause cell death.
-
- For these reasons, any moon base must
provide adequate radiation shielding to protect its inhabitants. However,
radiation shielding is best provided by dense material, which is expensive to
transport to the moon from Earth.
-
- Hence, naturally shielded areas, like the
recently discovered caves, are being earmarked as possible locations for human
habitation on the moon. These caves would afford its residents a whopping 130
to 170 meters of solid rock shielding, enough to halt even the highest energy
radiation.
-
-
September 18, 2024 MOON
CAVES - need to be explored? 4559
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------ “Jim Detrick” -----------
--------------------- --- Wednesday, September
18, 2024
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