 His analysis reveals that their technologically advanced civilization had attracted the attention of machines, who attacked with orbital bombardments that levelled the EMs' cities and cracked open the crust of the planet, permanently altering the ecosphere.The EMs used genetic engineering to adapt their bodies to use silicon and transistors for a nervous system.As the satellite is programmed to react only to high technology, not inbuilt features of organisms, the EMs are able to broadcast their message to other biological races unmolested.