Drill reaches Utah mine chamber where six trapped

Rescue crews drilled into a deep chamber where six miners are trapped in a collapsed Utah coal mine but heard no sound through a microphone lowered into the cavity.
"The fact that we have not picked any sound, I believe, should not be interpreted as bad news," Crandall Canyon Mine co-owner Robert Murray told reporters late on Thursday. "There could be a number of factors as to why sounds in there might not be picked up."
The six men have not been heard of since Monday when the mine caved in. Murray said an analysis of the air in the chamber indicated it contained 20 percent oxygen, no methane and only a small amount of carbon monoxide. "That is almost perfect air to support human life," he said.
Murray said the 2 1/2-inch (6-cm) drill had pierced through the chamber late on Thursday night. He said rescue worked would monitor the microphone while a larger, 9-inch hole was being drilled to insert a camera into the cavity.
Murray said that it would now take at least another four to five days to reach the miners but that if they were still alive, the hole could be used to provide food, water, and air while a larger opening was created to get them out. Officials say the men could potentially survive for weeks in an underground chamber if they were not killed by the initial collapse.
Asked if the men were definitely in the target reached, Murray replied: "No, we can't be sure but we think so. We think that's where they are... They didn't move far, I'm sure, from that area." Murray has insisted that an earthquake triggered the mine's collapse but geologists dispute that, saying that shaking recorded by their instruments was caused by the cave-in.
Controversy has also risen over reports that the miners were engaged in a dangerous operation called "retreat mining" when the shaft collapsed - though Murray has denied that such a technique was being used. Retreat mining involves supporting the mine's roof with a column of coal, then removing those pillars and allowing the shaft to collapse as miners move to safety.
The Crandall Canyon Mine is on a high desert plateau some 140 miles (225 km) south of Salt Lake City, in what is known as Utah's "castle country" because of the towering rock spires that dot the bleak landscape.