Chile's mining minister announced that a shaft wide enough to provide an escape for 33 trapped miners in San Jose should reach the men by Saturday — and that their rescue could begin anywhere from two to 10 days after that.
CNN reported rescuers have just another 89 metres left to drill to reach the men who are stranded in a cavern some 624 metres underground.
Once reached, the time frame for the rescue will be determined by a technical evaluation of the risks involved, Mining Minister Laurence Golborne said Thursday, meaning the miners could be pulled out as early as Monday or Tuesday.
The countdown hinges on whether the rescue team decides to use steel piping to line the walls of the shaft and reduce the risk of a rock fall or other obstruction jamming an escape capsule that will carry the miners to the surface, Golborne said.
Inserting straight pipe with walls of half-inch-thick steel through a curved and fractured section of the shaft also risks clogging the hole or knocking rock loose. If sections of pipe break apart or get stuck, it could slow the rescue.
The alternatives are leaving the raw "live rock" without any reinforcement, inserting a sleeve in the top section only, or encasing the entire shaft, a process that would delay the rescue for another 10 days after the decision is made.
"They are all possible alternatives," Golborne said. "There are risks and benefits we have to think about."
Golborne said a decision will be based on technical factors once a video camera is lowered to thoroughly examine the shaft's walls.
While the "Plan A" and "Plan C" drills have been slowed by efforts to keep them on target, "Plan B" resumed Thursday with fresh bits carving through the final 90 metres.
Reuters reported the miners' relatives had their spirits boosted by the arrival of rescue material onto the site.
Deliveries also included parts for a huge crane that will be used to help hoist the miners to the surface.