The Zito probe is a deep Earth probe launched by Giovanni Zito in the fourth book, the Opal Deception. It was released ten years ahead of schedule, and threw Foaly's predictions into disarray. It was able to be used early as Opal Koboi had given Giovanni Zito (whom she had mesmerised) the technology to cut through the crust without "frying half a continent". It was released into a rich high grade (around 80%) heamatite (iron ore) orebody which allowed it to travel to the core at 5 metres a second without being destroyed.
Objective and Description
The probe was a grapefruit sized object, encased in several million tons of molten iron. Giovanni Zito launched the probe by detonating an enormous nuclear explosion underground, which melted the iron and created a fissure. The orebody descended into the fissure at a speed of 16 feet per minute. The true mind behind the probe was a disguised Opal Koboi, who had mesmerized Zito into creating the probe. The true nature of the probe was to fall into a chute and cut a chunk out of Haven. Opal planned to do this by planting charges at a depth of 155 miles in chute E37 thus creating a new path of least resistance for the iron to fall through. If it had succeeded then not only would half of Haven be destroyed with around a 55% casualty rate, but fairy communication signals would be open for the world to hear.