What Can We Learn By Drilling Into The Earth’s Mantle?


So, guys, I just learned that drilling into
the earth can tell us about outer space. What is going on here?! Hi guys, Lissette here for DNews. Scientists
are drilling into the earth. We all know the Earth is made of three major layers – the
core, mantle, and crust, which is where we all live. The crust floats on the mantle,
a super-thick layer of mostly slowly moving rock. We’ve been trying to reach the mantle
since the 1960s, but despite numerous expeditions, have still not dug past the crust. By all
accounts, attempting to reach the mantle is dangerous and expensive, so why are we trying
so hard to get down there? Because the mantle can tell us a lot about
the history and formation of our planet in the universe. The mantle makes up 84% of the
Earth’s volume and is incredibly hot with temperatures that range from around 1000 degrees
celsius close to the crust and about 4000 degrees celsius near the core. The weight
of everything above it creates pressure that builds up tremendously the closer we get to
the core. The crust varies from 5 to 60 km thick, with the thinnest layers found under
the ocean. The farthest we’ve gotten was in the 1980s in Russia’s Kola peninsula, where
they dug for 20 years and managed a 12 kilometer-deep hole, which was probably not even halfway
to the mantle. This and many expeditions have failed because of technical difficulties like
improper equipment and just plain bad luck in choosing spots to drill. But this doesn’t
mean scientists have given up. More recently, a team of scientists from the
International Ocean Discovery Program (IODP) drilled into the ocean crust and were able
to retrieve rocks that showed signs of life . We’re not talking about mole people or green
big eyed kind of life, but microbial life. The rocks contained methane and hydrogen,
which as one of the researchers stated “microbes can ‘eat’ to grow and form new cells”.
This is huge! Similar rocks, gases, and conditions are found in other planets. So, according
to the researchers, these rock specimens can aid our search and understanding of how extraterrestrial
life may exist in similar inhospitable conditions in the depths of the universe. But reaching the mantle doesn’t just teach
us about space, it also teaches us about earth. The mantle’s activity is largely responsible
for the movement of tectonic plates, which scientists theorize influences volcanic activity,
earthquakes, mountain ranges, and movement in the oceans. So understanding the mantle
more can help us better understand the earth’s current topography and it’s history – Including
how our continents shifted throughout the ages and are shifting today. If we can drill
down to the mantle, researchers could have this type of information straight from the
source, increasing the accuracy. Right now we can only make inferences about
the structure of the earth based on how fast an earthquake’s’ seismic waves, travel through
the planet and the routes they take, what we can see on the crust, and the composition
of rock samples. It wasn’t too long ago that by chance a volcano ejected a diamond
from the mantle that confirmed that there is an ocean’s worth of water in the mantle’s
transition zone! Scientists learned this because it contained ringwoodite, with a certain amount
of water in it. This tiny rock made a huge difference. And look, these rocks are great,
but they are inconsistent – we don’t know when the next mantle rock will be spewed out
of which volcano or if it will be intact enough for scientists to derive meaningful conclusions.
We got lucky with this diamond, but often these rocks are too damaged. Most have been
belched out from volcanoes, ejected by tectonic plate crashes, or carried upward to the ocean
floor. These treacherous and often erratic journeys leave scars on them, and leave scientists
with messy data. It’s hard to know what characteristics were a result of the journey
vs reflective of the mantle itself. So drilling down to the mantle could mean
that we would finally be able to get pristine samples of the mantle, and even an entryway
for further exploration. It could give us a clear look at the mantle’s composition,
how it’s moving, and more accurate readings of its velocity, pressure, and temperature.
In essence, what the earth and possibly the universe is made of. But the drilling we most often hear of is
tied to oil. To learn where oil comes from, check out this video over on TestTube News.

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