Copiapo, Chile (CNN) -- There may be light at the end of a nearly completed tunnel for the 33 men trapped since August 5 almost half a mile below ground, with rescuers expected to reach them within a day, Chile's mining minister said Friday afternoon.
"Hopefully before that," Mining Minister Laurence Golborne told reporters about the time when a rescue drill is expected to pierce the roof of the mine. As of Friday afternoon, it was 40 meters (about 130 feet) away. "Maybe tomorrow morning, early Saturday. We have to wait and see."
Once the mine has been reached, the rescue process could begin within three to four days, Golborne told reporters. But mine engineers must decide first whether they need to encase the shaft with steel tubing to prevent rockfalls and further collapses during the extraction process. "If we do a full casing of the hole, those three to four days could go to eight to 10 days," Golborne told reporters.
One of the rescue coordinators, Rene Aguilar, an engineer for state copper company Codelco, said this week they may encase just the first 100 meters (328 feet) of the shaft, a process that could take just 10 hours.
Before anyone can be rescued, the hole must be widened so that the rescue capsule -- dubbed the Phoenix -- can land cleanly inside the tunnel without getting hung up on obstructions, Golborne said. To accomplish that, explosives will be lowered to the miners for use in widening the shaft, said Golborne, who expressed little concern that the subterranean pyrotechnics would pose any danger to the men.
"We have to take into consideration that we are talking here about miners that have experience, many of them are licensed to use explosives, they know how to manipulate them, they have already made the holes that they need to set the right quantities of explosives. ... So it will be a very controlled explosion that will be made after we break into the tunnel."
Then, authorities will lower a doctor and a rescuer into the chamber, Health Minister Jaime Manalich said. Medical and rescue personnel will be in place to start extracting and treating the miners Monday night, he said.
Once the miners have been extracted, they will undergo about two hours of health checks at a field hospital set up at the mine.
Barring complications, it will take about 24 to 36 hours to remove all the miners through the 2,300-foot hole, Manalich said. They will then be flown by helicopter to a hospital in the town of Copiapo -- approximately a 15-minute flight.
Miners who are healthy enough will be allowed to visit briefly with family members in a reunion area before being taken to the hospital, Manalich said.
Health officials have increased the miners' physical activity in recent days to gauge how they can handle the stress of being removed, Manalich said. The overall response has been good, he said, though some miners have exhibited anxiety or have had minor cardiac issues.
The miners have been in contact with the outside world through a small bore hole that sends them food, water, supplies and other necessities.
Rescue crews have been drilling three separate, wider holes to send down the rescue capsule and hoist the men to the surface. Those rescue attempts have been labeled Plans A, B and C.
Plan B was close to reaching the trapped miners at a depth of 624 meters (2,047 feet). The drill had reached 584 meters (1,916 feet) before it was stopped early Friday morning to replace the bit, Golborne told reporters.
Chilean President Sebastian Pinera said September 19, during his last visit to the site, that he planned to personally hug each of the miners as they were pulled from the rescue shaft. He is due to depart on a government tour to Europe in mid-October.
First lady Cecilia Morel Montes told reporters Friday night that her husband was in the south.
"He has a lot of obligations," she said. "Undoubtedly, he would like to be here permanently. But he also has to be permanently in a lot of other places and it's necessary to continue governing."
She said the crisis faced by the miners has brought Chileans together. "They have become very familiar to every Chilean," she said. "All Chileans are equally expectant, equally nervous; there's a lot of empathy toward the families."
She added that the men's liberation will occur "as soon as possible," but only after every precaution is taken to ensure their safety.
CNN's Lonzo Cook, Patrick Oppmann and Karl Penhaul contributed to this report.