Copiaco, Chile (CNN) -- The 33 miners trapped far below the surface of the Earth appear in mind and spirit to be as strong as "solid rock" and are working well together as a team, Chilean Health Minister Jaime Manalich said Thursday.
Each miner has been given a task, he said. For example, the men have been divided into teams of four plus a team leader who are responsible for managing the tubes that carry the supplies that are their lifeblood.
One miner is in charge of setting the schedule of when they eat and sleep, another of nutritional matters and another of medical needs, he said.
They have been asked to simulate night and day on their own and to sleep in shifts -- half the men sleep while the other half work and make sure everyone on the other half is OK.
Representatives of NASA arrived on site on Wednesday. After assessing the miners' situations and needs, the NASA experts will present options and recommendations Friday evening.
NASA engineers are also helping design the conveyance -- a cage or a capsule to be equipped with oxygen, light and communication abilities -- that will be used to hoist the miners to the surface.
Manalich predicted it would take 1-1/2 to 2 hours to lift each man to safety, a process that would take about three days.
Though no decisions have yet been made, Manalich said rescuers were prepared to arrange for the men to be blindfolded or sedated as they are hoisted up.
In addition, he said, contingency plans are being made to lift out any miners who may be unable to aid in their rescue due to illness or injury.
But Manalich said he is now concentrating on another mission, one that has taxed him even as it has affected the miners: "We are now in a different phase, to keep them healthy and alive for a long period of time in these extreme conditions, and I feel that is a very hard task for my shoulders. It is a hard mission."