The Moss That Could Terraform Mars

Wow, so we're 'protecting the environment' of Mars now? Is every dead rock somehow a precious thing? Bad news for spreading to the stars - the universe is likely jam-packed with nothing but dead rocks.

We don't have an ethical duty to keep every rock as we found it. Else we'd have to blast Earth back to a naked magma sphere, to be perfectly ethical?

There's room for us in the universe too.