Russian engineers begin drilling the world's deepest hole - May 24th, 1970

On this day in 1970, Soviet engineers began drilling the deepest man-made hole ever dug.

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Episode Transcript

Speaker 1 (00:00):
This Day in History Class is a production of iHeartRadio.
Hello and Welcome to This Day in History Class, a
show that plumbs the depths of history one day at
a time. I'm Gabe Lucier and in this episode, we're
looking at well a hole in the ground. But bear
with me because it also happens to be one of

(00:21):
the most important contributions of Soviet era science, as well
as an impressive feat of engineering prowess and patience. The
day was May twenty fourth, nineteen seventy, Soviet engineers began

(00:44):
drilling the deepest man made hole ever dug, known as
the Cola Super Deep Borehole, it ultimately reached a depth
of approximately seven and a half miles below the Earth's surface.
For reference, that's about four thousand feet deeper than the
deepest point of the ocean and equivalent to the height

(01:05):
of Mount Everest and Mount Fuji combined. It took the
Soviets roughly twenty years to dig the hole as deep
as they did, and while the project was abandoned abruptly
in nineteen ninety two, more than three decades later, the
Borehole remains the deepest artificial point on Earth. Before we

(01:26):
get to why anyone would want to dig such a
deep hole. Let's talk a little more about the hole
itself for starters. It was actually a series of holes
that branched off from a central one. The deepest was
called SG three, and it stretched about forty thousand, two
hundred and thirty feet deep into the planet's outermost layer.

(01:49):
But if you're imagining a yawning, bottomless chasm, think again.
As the hole is actually only nine inches in diameter,
there was no risk of falling into it, but scientists
still could have dropped their keys down there, so they
had to be careful. The borehole was located, as its
name suggests, on the Kola Peninsula in northwestern Russia. Drilling

(02:12):
was conducted there at a scientific research station not far
from the Norwegian border. As for why the Soviets began
drilling in the first place, the main reason was for
the sake of science. Researchers simply wanted to learn more
about the Earth's crust, including what it was made of
and how it had formed and changed over time. Extracting

(02:35):
resources like fossil fuels wasn't a part of the mission,
but the Soviets did collect rock samples, which in some
cases proved just as interesting as the ones NASA was
bringing back from the Moon, and speaking of the moon landing,
that ties in with the other reason the Soviets were
so intent on digging the deepest hole possible bragging rights.

(02:57):
The US had overtaken the USSA are in the space race,
but the race to the center of the Earth was
still anyone's game in the eyes of the press and
the public. Digging a hole was far less flashy than
space exploration, but both superpowers were still eager to claim
whatever glory there was in conquering the deep frontier. In

(03:20):
nineteen fifty eight, the US launched its own Cold War
drilling operation, known as Project Mohole. Its rather lofty goal
was to reach the Earth's mantle, the layer beneath the
planet's crust, by drilling deep into the floor of the
Pacific Ocean, where the crust is thinner. Unfortunately, progress was slow,

(03:42):
and in nineteen sixty six, Congress cut the project's funding
after learning the drillers had only gone a tenth of
a mile after roughly eight years on the job. Meanwhile,
in the Soviet Union, plans were proceeding much more smoothly
thanks to several closely guard did technical advances. Drilling officially

(04:03):
began on May twenty fourth, nineteen seventy, and would continue
with occasional pauses until nineteen ninety two. At first, the
team employed a modified drilling rig used for drilling oil wells,
then in nineteen seventy four it upgraded to a purpose
built rig installed on site to allow them to dig

(04:24):
even deeper. The crew made many surprising discoveries the deeper
they went, including the presence of water, which had been
thought impossible due to the impermeability of the rock layer
above it. The biggest surprise, though, by far, was the
discovery of more than a dozen species of fossilized micro organisms,

(04:45):
many of which were more than two billion years old.
Those relics of ancient life were found four miles beneath
the surface, raising all kinds of questions about how the
creatures could have survived the extreme pressures and tempered of
those depths, and whether any other life forms still might.
As you might imagine, drilling deep into the earth and

(05:08):
finding signs of life spurred some wild rumors amongst the locals.
The most persistent claim was that the scientists had drilled
into an extremely hot cavern by mistake, and when they
lowered a microphone to investigate, they heard what sounded like
tortured screams. Of course, that was all an urban legend,

(05:29):
but to this day you'll still find some folks in
the region who insist the borehole is really an entrance
to hell, though again, with only a nine inch diameter,
you'd have to be a pretty skinny demon to slip
through it. The Kola Super Deep Borehole was supposed to
go as deep as possible, ideally all the way to

(05:50):
the Earth's mantle, some twenty five miles beneath the surface
in the end, though after almost twenty years of drilling,
the Soviets only made it about a third of the
way there. Part of the reason the project was halted
was due to the collapse of the Soviet Union and
all the political and economic turmoil that came with it,

(06:10):
but there were other factors as well. For one thing,
the temperatures at the bottom of the seven and a
half mile whole far exceeded expectations. The team had anticipated
heat of about one hundred degrees celsius or two hundred
and twelve degrees fahrenheit, but instead temperatures soared to one
hundred and eighty degrees celsius or three sixty five fahrenheit,

(06:33):
nearly twice as hot as their models had predicted. Not
only was that hot enough to deform the drill bits
and other apparatus, it was also hot enough to cause
a change in the rocks themselves. The scientists reported that
rocks below the first fifteen thousand feet behaved more like
plastic than solid rock. They were more porous and permeable

(06:56):
than the rocks found farther up, and combined with the
high temperatures that made drilling through them next to impossible.
With no clear way forward and future funding up in
the air, the scientists and engineers at COLA had no
choice but to call it quits. Data produced by the
drilling project continued to be studied at COLA for the

(07:16):
next several years, but eventually the research station was closed
completely and the borehole was sealed with a heavy metal cap.
The abandoned dig site has since become a popular destination
for eccentric tourists, but since you can't actually look into
the hole itself, you might be better off visiting the
nearby mining town of Zapple. Yarny its home to the

(07:40):
Coola Core Repository, which displays many of the rock samples
recovered during the drilling. Unlike the space race, nobody really
won the race to the Earth's mantle. There have been
a few promising efforts over the years, including drilling projects
led by Germany and Japan, but as of twenty twenty three,
Lacola Super Deep Borehole is still the one to beat.

(08:06):
I'm Gabe Lucier and hopefully you now know a little
more about history today than you did yesterday. You can
learn even more about history by following us on Twitter, Facebook,
and Instagram at TDI HC Show, and if you have
any comments or suggestions, you can always send them my
way by writing to this Day at iHeartMedia dot com.

(08:29):
Thanks to Chandler Mays and Ben Hackett for producing the show,
and thanks to you for listening. I'll see you back
here again tomorrow for another day in History class.