Nothing is beyond us, the new legends say. So choose well. - David Brin

Analog, or Asimov's Magazine, or The Magazine of Fantasy and Science Fiction.

It also became clear why the nations were expected to commence major space enterprises. Henceforth, the raw materials for industrial civilization were to be taken from Earth’s lifeless sisters, not the mother world. All mines currently being gouged through Terra’s crust were to be phased out within a generation and no new ones started. Henceforth, Earth must be preserved for the real treasures—its species—and man would have to look elsewhere for mere baubles like gold or platinum or iron.

The worst mistake of first contact, made throughout history by individuals on both sides of every new encounter, has been the unfortunate habit of making assumptions. It often proved fatal.