The effort to save 33 men trapped deep in a Chilean mine is an unprecedented challenge, mining safety experts said Tuesday. It means months of drilling, then a harrowing three-hour trip in a cage up a narrow hole carved through solid rock.
If all of that is successful, the freed men will emerge from the earth and "feel born again," said an American miner who was part of a group dramatically rescued in 2002 with similar techniques. But that rescue pulled men from a spot only one-tenth as deep.
"They're facing the most unusual rescue that has ever been dealt with," said Dave Feickert, director of KiaOra, a mine safety consulting firm in New Zealand that has worked to improve China's dangerous mines. "Every one of these rescues presents challenging issues. But this one is unique."
First, engineers must use a 31-ton drill to create a "pilot" hole from the floor of the Atacama Desert down 2,200 feet (700 meters) to the area in the San Jose mine where the men wait.
Then, the drill must be fitted with a larger bit to carve out a rescue chimney that will be about 26 inches (66 centimeters) wide - a task that means guiding the drill through solid rock while keeping the drill rod from snapping or getting bogged down as it nears its target.
Finally, the men must be brought up one at a time inside a specially built cage - a trip that will take three hours each. Just hauling the men up will itself take more than four days - if there are no problems.
"Nothing of this magnitude has happened before; it's absolutely unheard of," said Alex Gryska, a mine rescue manager with the Canadian government.
Gryska said he is confident Chile's state-run Codelco mining company, with its vast expertise in the world's top copper-producing nation, would successfully drill the hole out. But he said he is worried about the three to four months officials say it will take to do so - and the key role the miners themselves will play in their own rescue.
Chilean officials said the miners will have to remove upward of 3,000 tons of rock as it falls into the area where they are trapped. There is little danger to the men - the area includes a shelter and about 500 meters (yards) of a shaft outside that. But as the rock starts to fall a month from now, the men will work in nonstop shifts to remove it with wheelbarrows and industrial sweepers.
"The thing that concerns me is welfare of workers, their mental state. That will be real tough," said Gryska. "From a health perspective, it's hot down there. They're talking about working 24/7 in 85 degrees for two months. Their mental state for that work will be critical."
Early on, Chile's Health Minister Jaime Manalich said at least five of the men showed signs of depression. But spirits have improved with a supply of water, food, special clothes to keep them dry in damp conditions and the first verbal communication with loved ones this week.
Late Tuesday, the government released another video of the miners that shows them smiling, shaved and wearing red T-shirts. The short video, which doesn't appear to have sound, is a stark contrast to previous videos that pictured the men shirtless and more subdued, with some getting emotional while recording a message for loved ones.
Earlier, Chilean officials met with four "life sciences" specialists from NASA in Santiago.
Michael Duncan, NASA's deputy chief medical officer who is leading the team in Chile, said his group had been asked to provide help in nutrition and behavioral health.
Duncan, speaking at a news conference in Santiago, said his team viewed two videos the miners made of themselves and their surroundings - and they clearly raised some concern about weight loss.
He said a priority was increasing the miners' caloric intake, getting them on a regular sleep schedule and ensuring they remain optimistic.
"These miners showed us tremendous strength in surviving as long as they did without any contact with the surface," he said. "What we want to try to avoid is any kind of situation of hopelessness on the part of the miners."
That could mean increasing their contact with the outside world - including bringing in celebrities or even astronauts who have survived long periods of isolation in space, Duncan said.
If the miners remain healthy during their long period underground and if the drilling goes as planned, they will then face the ordeal of being stuffed into a tubular, metal cage for three hours as they are slowly pulled up.
Experts say one of the few times such a technique was used was when nine U.S. miners were hauled out of the flooded Quecreek Mine near Somerset, Pennsylvania, in 2002. But those men were trapped for just three days 73 meters (240 feet) underground.
Quecreek survivor Mark Popernack noted the Chilean miners "already went through more than what we went through," but the Somerset, Pennsylvania, resident said no matter the method, "to come up is the best thing in the world."
"If they make it, if they get that hole drilled, when they come out of there, they'll feel like they're being born again," said Popernack.
"Enjoy the ride, that's my advice to them," he said. "It'll be a long ride, but they'll enjoy it. Because when they see the light of day, they're going to feel pretty good."