Inner Space: A World of Giants

The Space Shuttle and International Space Station (ISS) put on a great light show these past few nights as they soared over the region. For a close-up view, you can check out NASA TV and watch the astronauts at work during missions to the ISS. 

Working in a hostile environment like the vacuum of space is a daunting challenge, with temperature swings of hundreds of degrees depending on whether you’re facing the sun or the void of space. And don’t forget the threats from UV radiation, micro-meteoroids, and even space junk. Space suits have come a long way since the Apollo moon landing suits, and it’s much easier for astronauts to work while remaining safe.

Closer to home, another group of explorers is conducting work and research in an environment every bit as hostile as outer space. Like astronauts, these Earth explorers, or terranauts [from the Latin terra (earth) and the Greek -nautes (sailor)], also must wear protective suits in order to stay alive as they study giants almost 1,000 feet underground.

These giants are huge crystals of selenite, which is a form of crystallized gypsum (the same material used in drywall). The largest crystals are more than 11 meters (36 feet) long and weigh more than 50 tons. This amazing, otherworldly cavern has been dubbed Crystal Cave of Giants, and was discovered accidentally by silver mine workers in Naica, Mexico in 2000.

The cavern is more than 300 meters (900 feet) below ground. Thanks to the cavern’s location near a magma chamber, the temperature holds steady at around 50 degrees Celsius (122 degrees Fahrenheit). It’s also quite humid, with a relative humidity of more than 90%. Using the National Weather Service Heat Index formula, this makes it feel like 179.8 degrees Celsius (355.7 degrees Fahrenheit) in the cave!

To put this in perspective, water boils at 100 degrees Celsius (212 degrees Fahrenheit).

The stresses on the human body are tremendous, and working in the cave can be fatal without wearing special cooling suits.

An insulated vest is worn next to the body to protect skin from frostbite. An “ice vest” made of frozen gel-filled pouches is worn on top of the insulated vest. The idea is to keep the body’s core from becoming overheated. A pair of rugged overalls is worn over the ice vest. The overalls not only keep the ice vest from melting too quickly, they also protect workers from the razor sharp edges of the crystals.

Workers also must wear a respirator, and breathe chilled air. This is accomplished by wearing a backpack cooler holding frozen metal ice bottles. A fan blows air over the frozen bottles and into a face mask.

Even with the protection, it’s tough to spend much time in the cave. According to one cave explorer, “Every minute you stay inside, the more unbearable it gets. You begin to breathe heavy, your heart rate jumps up and sweat is pouring down your hands . . . It becomes easy to get disoriented from the heat and your higher cognitive functions start to shut down.”

According to scientists, the crystals in the cave formed over 5 million years as mineral-rich water remained at a steady 50 degrees Celsius (122 degrees Fahrenheit). The submerged crystals were exposed when silver mine workers broke through into the cavern and drained the hot, mineral-rich water. With the cavern drained, the crystals are no longer growing and the temperature is slowly cooling.

Sometimes there really is something new under the sun — or under the ground.