Post by a425couple
This was a pleasant, short, very early Clarke book.
Takes place on the moon in about year 2165. ---
IMHO, a fine book, but not in the league of 2001, 2010,
Hammer of God, Songs of Distant Earth, Rendezvous with Rama,
Fountains of Paradise, or Imperial Earth.
Arthur Clarke wrote of many totally new ideas, and
a fair number of those ideas /'proposals' did later
His real 'advance' in this book, was mining of the moon
at VERY deep depths to get to precious materials.
(See my June 11 post about "Earthlight" about minerals.)
In this book, on the moon, they drilled a hole 100 km
deep to get to the core where rich deposits of metal are.
Counter pressure is done by injecting heavy silicone oil.
Currently, on Earth, our deepest mine is under 4 km.
Here are reads:
The top ten deepest mines in the world - Mining Technology
Sep 11, 2013 - AngloGold Ashanti's Mponeng gold mine, located south-west
of Johannesburg in South Africa, is currently the deepest mine in the
world. The operating depth at Mponeng mine ranged from between 2.4km to
more than 3.9km below the surface by the end of 2012.
List of deepest mines - Wikipedia
This is a list of the deepest mines by maximum operating depth.,.
Number, Name of mine ... "[SLIDESHOW] The Deepest Underground Mines in
Terrifying Facts About the World's Deepest Gold Mine - Gizmodo
Dec 16, 2013 - Oh, the things humans will do to get their grubby hands
on gold—a metal mostly prized for its ornamental use, hoarded in bank
vaults and jewelry boxes, though we've arbitrarily decided it's worth,
uh, its weight in gold.* The deepest gold mine in the world is Mponeng,
a 2.5-mile hole in the ground in South Africa.
How hot is the deepest mine in the world?
The rock face temperature reaches 60 °C (140 °F). By 2008, the mine
reached 3.9 km (2.4 mi) underground. This made it the deepest mine in
the world, surpassing the 3.5 km (2.2 mi) deep East Rand Mine by a
How deep is the deepest hole in the world?
The Kola Superdeep Borehole was just 9 inches in diameter, but at 40,230
feet (12,262 meters) reigns as the deepest hole. It took almost 20 years
to reach that 7.5-mile depth—only half the distance or less to the
mantle.Feb 19, 2015
"But the most intriguing discovery made by the Kola borehole
researchers is undoubtedly the detection of biological activity
in rocks more than two billion years old. The clearest evidence
of life came in the form of microscopic fossils encased in
organic compounds that remained surprisingly intact despite the
extreme pressures and temperatures of the surrounding rock.
While data produced by the Kola drilling project continues to be
analyzed, the drilling itself was forced to stop in the early 1990s
when unexpectedly high temperatures were encountered. While the
temperature gradient conformed to predictions down to a depth of about
10,000 feet, temperatures after this point increased at a higher rate
until they reached 180 °C (or 356 °F) at the bottom of the hole. This
was a drastic difference from the expected 100 °C (212 °F). Also
unexpected was a decrease in rock density after the first 14,800 feet.
Beyond this point the rock had greater porosity and permeability which,
paired with the high temperatures, caused the rock to behave more like
a plastic than a solid and made drilling near impossible."