So far, 15 of the 33 miners have made the 15-minute journey in the Phoenix II escape pod, one of three designed for the operation by NASA and Chilean Navy engineers.
With an inside diameter of 21” (0.5m), a height of 14’ (4.2m) and weighing 420kg, the Phoenix II pod was chosen for the rescue as it is small enough to manoeuvre narrow points and kinks in the shaft.
The design of the pod can be traced to a mining disaster that took place in Germany in 1955 when three miners were trapped in Dahlbusch colliery following an underground fire.
Engineers there developed a device that could be dropped into a small borehole and lowered and raised quickly and repeatedly. The three miners were trapped 855m below the Earth’s surface, although a vertical 42m borehole was drilled above them from the next level in the mine.
The system that was developed, the Dahlbusch Bomb, had a length of 2.5m and a diameter of 38.5cm and has been deployed numerous times, notably in 1963 when it was used to rescue 11 miners trapped at 58m in the Lengede iron ore mine in Germany.
Phoenix II, which will be lowered to a depth of 625m at a speed of 91cm per second, has retractable wheels at the top and bottom of the capsule to aid its journey.
Before the ascent the miners are being fitted with a biometric belt so that doctors can monitor vital signs, along with an oxygen mask and a helmet containing two-way communications equipment.
Once in Phoenix, a harness straps the miner to the centre of the capsule before being winched to the surface.