8-1 Exploring A Crystal Cave

Narrator: Hidden a thousand feet beneath the surface of the earth. A natural wonder. A scientific mystery. A place as deadly as it is beautiful. Nothing like it has ever been discovered.

But it's so hot, exploring it could cost lives. These crystals may determine if life exists on other planets. But only if science can unlock the secrets of the Giant Crystal Cave.

April 2000. What starts as an ordinary workday for two miners transforms into a remarkable discovery. The attention of the world's scientists turns to the mine. A stunning cave a thousand feet down. The cave is filled with crystals.

And now, these experts in biology, space exploration, and geology will attempt to shed light on the discovery. The newcomers have unique skills to help unravel this mysterious discovery.

Chris McKay, NASA scientist, Mars mission planner. Penny Boston, expert in finding life in extreme environments. Stein-Erik Lauritzen, specializing in geological time.

It's a half-hour winding drive, a thousand feet down toward the center of the earth. It's almost 104 degrees here. Humidity 60 percent.

The site that greets them isn't what you'd expect in a mine. A busy high-tech nerve center. Gonzalo Infante heads up the operation. It's taken his team years to invent life support systems and safety protocols that make exploring the cave possible.

His team has also invented camera equipment that can hold up in the punishing heat. Beyond this critical mission control is a tunnel, and the newcomers are eager to see what lies beyond.

Nothing can prepare the scientists for what lies before them. Their first look at the magical Crystal Cave.

These stunning pillars are made from the same common mineral as drywall, called gypsum. But there's nothing common about these crystals. They've grown five times larger than any previously discovered.

Prof. Paolo Forti: This is an order of magnitude of difference. This is astonishing.

Narrator: The giant crystals are extremely rare because gypsum takes a long time to grow. Two critical ingredients are needed: submersion in water and heat in excess of 120 degrees. So conditions inside the cave must have been stable and underwater for a very long time to create such massive crystals.

Prof. Paolo Forti: Chris, look to this rosette. Gypsum roses! It's gigantic! In normal caves, are of 10 centimeters in diameter. Look this. It's astonishing.

Narrator: The Crystal Cave isn't just hot. It's deadly. The crystals are searing hot to touch. Razor sharp, but also soft, like human fingernails. Here, the Sahara meets the Amazon, all in one claustrophobic cavern.

At temperatures above 113 degrees, the body tries to shed heat. But in 100 percent humidity, that sweat can't evaporate, and the heat is trapped inside the body. The vital signs of the explorers are closely watched in mission control because cells can die and organs can fail.

It's time to return. They've stayed 10 minutes, twice as long as the safe limit.

Explorer: Copy. We are coming out.

Explorer: Okay, let's go. Should we follow you, Tulio, now?

Tulio: Yeah.

Explorer: The same way we came in?

Tulio: Sí. Okay. Respect the order, please. Okay.

Narrator: They're torn between their bodies, which are screaming for them to leave, and the sight that compels them to stay.

Explorer: Okay, please don't stop. Okay.

Narrator: Dr. Giovine checks vital signs. Blood pressure and pulse are dangerously high. And with mission control's temperature hovering near 104 degrees, their bodies' core temperatures take a long time to cool down.

The scientists now understand the obsession of the Naica explorers. The Crystal Cave is breathtakingly beautiful and deadly. It's a unique scientific enigma that they're determined to unravel.