Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, September 6, 1994 TAG: 9409080020
SECTION: NATIONAL/INTERNATIONAL PAGE: A-4 EDITION: METRO
SOURCE: Associated Press
DATELINE: WASHINGTON LENGTH: Medium
- Jules Verne
``A Journey to the Centre of the Earth,'' 1864.
One hundred thirty years later, words still fail the explorers who venture into the Earth.
``The whole thing is pure exploration,'' said Bill Stone. ``If you haven't been there, you can't understand it.''
For 44 days this spring, Stone and his teammates were underground in a natural abyss in southern Mexico, descending three-quarters of a mile vertically under the surface, then swimming through a half-mile long underwater tunnel to an air-filled cavern beyond.
They eventually got down to 4,839 feet - just short of a mile - the deepest humans have gone in a cave in the Western Hemisphere, the fifth deepest in the world. One member of the expedition died in the attempt.
Why did they do it? Because, as the cliche goes, it was there.
``It's unknown territory down there,'' Stone said. ``It's basically the last bastion on this planet of truly manned geographical exploration. If you ask `Who has been doing exploration in the last 30 years?' you can pretty much say it's been 12 Apollo astronauts who set foot on the moon and the cave explorers of the world.''
Not spelunkers. Not even cavers. Explorers.
``I think of myself as a modern age explorer, that's what this is all about,'' Stone said. ``It happens to be the frontier right now.''
This particular frontier, Sistema Huautla, is a 35-mile-long complex of interconnected deep limestone caverns in the Mexican state of Oaxaca. Previous attempts at exploration of the cave were stopped by a passage flooded to the ceiling with water. No scuba diving equipment was adequate.
When he's not rappelling down a shaft or swimming through nearly opaque water underground, Stone, 41, is a research structural engineer at the National Institute of Standards and Technology in Gaithersburg, Md., a place where inventors can stretch their minds at government expense.
With eight colleagues, he designed a life-support system that allows a swimmer to remain underwater for 6-8 hours - twice that, when two units are joined.
Their goal was a ``sump'' at the deepest known point in the Mexican cave where the water completely filled the sloping tunnel. The explorers were to don their backpacks and swim into the watery obstacle, seeking a way on to presumed air-filled passages on the other side.
``You cannot get to where we got this year with traditional scuba diver apparatus,'' he said ``It's just too inefficient, blowing away all that gas every time you breathe underwater.''
His device is based on the space suit principle, but it's more complicated because built-in computers adjust a helium-oxygen mixture for the diver, while astronauts set and forget their pure oxygen flow. Exhaled gas is recirculated to remove carbon dioxide by a special process.
``Otherwise, you'd be wasting precious molecules,'' Stone said. ``Every pound carried to that dive site is paid for in sweat and blood.''
Cave explorers carry in their heavy equipment and supplies and bring most of it out. Their ethic is not to litter.
``Ten thousand feet of rope, over 100 shafts you have to go up and down every time you carry something to the dive site,'' Stone said of the Mexican cave. ``You are also carrying your body weight in addition to whatever your cargo is.''
To reach the underwater passage, Stone's team - which numbered up to 20 at times - rigged more than 2 miles of rope down large, steeply descending tunnels, following a river most of the way. There were 60 sheer drops - the longest 360 feet - in inky blackness, lit only by the puny glow of their headlamps and backdropped by the hiss of falling water.
The cavers also needed to string ropes to cross 30 other places where the boiling underground river was too dangerous to wade or swim.
Where they stopped, Stone said, is considered the most remote point yet reached by humans inside the Earth, 4,839 feet deep, miles from where they entered the cave.
by CNB