The Great Pulse

The great pulse was a gamma ray burst, that passed straight through the solar system. It is considered to have marked the end of The First Sol War. In space it caused major cancer out break and disastrous equipment failures, destroying the already strained solar system economy. However earth was hurt the most. It stripped the atmosphere's ozone layer, and due to the The Orbital Wall formed from the war meant no one could escape. So the inhabitants of earth moved underground, building the place known as Terralan.