> Those "martian" cities will be needed as giant shelters on Earth before we can build them on Mars. Which is a far stronger argument for building them than an

> Those "martian" cities will be needed as giant shelters on Earth before we can build them on Mars. Which is a far stronger argument for building them than any space program. The harder problems of colonizing mars do not include "can we build domes without a substantial pressure differential tearing them apart".