Chile mine rescue: 5 final steps to freedom

4. The capsule descends

The 13-foot-long, 926-pound rescue capsule, called the Phoenix, was designed by NASA engineer Clinton Cragg with the Chilean Navy. It can carry one person at a time. It will descend into the shaft with a paramedic and also a rescue coordinator, who will assess the miners and determine a final order for evacuation (although the general order already appears to be determined).

The capsule is about 21.5 inches in diameter. Mr. Cragg described the capsule to AOL News:

The capsule also has to be able to withstand the friction of traveling up and down the rock walls of the mine shaft multiple times, so the NASA team gave it wheels. (And suggested an alternative: Teflon-coated sliding blocks attached to the outside of the capsule.)

"Metal scraping on rock would not last," Cragg said.

It had to have an escape hatch, in case it got stuck in the shaft. It also got a safety harness, a clock, and a way to communicate with the miner inside. NASA's medical experts weighed in, and other design elements were added: an oxygen tank, a light and a flat space in the bottom of the capsule for miners to stretch their legs.

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