Complex sentence: One of the miners, Conway, reveals that the Daleks are planning to drop a bomb into their mineshaft to punch out the Earth's core, which will be replaced with a giant motor enabling the aliens to pilot Earth to their home world of Skaro.
Split into simpler sentences: One of the miners, Conway, reveals that the Daleks are planning to drop a bomb into their mineshaft to remove the Earth's core. Following the explosion, the core will be replaced with a giant motor enabling the aliens to pilot Earth to their home world of Skaro.