COPIAPO, Chile — Each of the 33 miners trapped a half-mile underground lived on two spoonfuls of tuna, a sip of milk, a bite of crackers and a morsel of peaches. Every other day.

They were so careful in eating what was supposed to be a two-day emergency supply that when the outside world finally reached them 17 days after a mine collapse, they still had some food left.

The discipline the men have already shown will be essential during the four months it may take rescuers to dig a hole wide enough to get them out of their shelter. The first communications with the trapped miners, now able to talk through a fixed line with their rescuers above – show how determined they have been to stay alive.

“We heard them with such strength, such spirit, which is a reflection of what for them has been a gigantic fortitude and a very well-organized effort,” Mining Minister Laurence Golborne said Tuesday after talking with the miners at length the night before through an intercom system lowered into their underground refuge. “The way that they have rationed the food, just as they’ve performed throughout this crisis, is an example for all of us.”

The miners were plunged into darkness by the Aug. 5 collapse of the main shaft of a gold and silver mine that runs like a corkscrew for more than four miles under a barren mountain in northern Chile’s Atacama desert. They gained contact with the outside world Sunday when rescuers drilled a narrow bore-hole down to their living-room-sized shelter after seven failed attempts.

“It’s been like a heart that’s breaking, but we’re thankful they’re all alive,” bore-hole driller Rodrigo Carreno told The Associated Press as he prepared to leave Tuesday. “We did everything we could to save them, and in the end we succeeded.”

The miners said they have honored the same hierarchy they used on any work shift, following the directions of 54-year-old shift foreman Luis Urzua.

They conserved the use of their helmet lamps, their only source of light other than a handful of vehicles whose engines contaminate the air supply. They fired up a bulldozer to carve into a natural water deposit, but otherwise minimized using the vehicles that contaminate the available air.

The miners can still reach many chambers and access ramps in the lower reaches of the mine, and have used a separate area some distance from their reinforced emergency refuge as their bathroom. But they have mostly stayed in the refuge, where they knew rescuers would try to reach them.

The room has become stiflingly hot and stuffy. Leaving it allows them to breathe better air, but wandering too far is risky in the unstable mine, which has suffered several rock collapses since the initial accident. It’s also spooky, since headlamps can illuminate only small areas of the vast space.

Rescue efforts advanced considerably Tuesday as a third bore-hole prepared to break through to the miners, and a huge machine arrived from central Chile to carve out a tunnel just wide enough for the miners to be pulled out one-by-one. That machine won’t begin drilling for several days.

Andres Sougarret, the rescue effort’s leader, estimated that it would take three to four months to pull the men out. But Davitt McAteer, a former assistant secretary of the U.S. Mine Safety and Health Administration, called that “perhaps the most conservative model.”

“Twenty-five hundred feet is not a terribly, terribly big hole to drill,” McAteer said. “We ought to be able to get them out in a period of weeks, not months.”

Meanwhile, three 6-inch-wide shafts will serve as the miners’ “umbilical cords” — one for supplies, another for communications and a third to guarantee their air supply.

A steady flow of emergency supplies was sent down to the miners on Tuesday in a rocket-shaped metal tube called a “paloma,” Spanish for dove, which takes an hour to descend.