Spice harvesteredit

From Dune

A Spice Harvester is a large, heavy, mobile factory that is dropped by carrier ships (known as Carryalls) onto spice fields. These machines would then harvest and process the spice off the top of the desert floor.

This immense farming mechanism is used solely on Arrakis, as it was the only known source of spice before the Tleilaxu developed a substitute.

Because of the vibrations caused by the harvesters, 2 or 3 ornithopters (called spotters) flew in the sky above the spice harvester, watching for wormsign (an obvious sign that a sandworm is approaching). Upon detecting wormsign, the harvester would be picked up immediately to clear it out of the way. A sandworm can be large enough to swallow the harvesters.

A good example of this process is seen in Dune (novel) when Duke Leto Atreides travels into the desert to inspect the process.