Ever since humans became a spacefaring species, settling down on other planets has seemed an inevitability—even a necessity. Scientific titans including Stephan Hawking and Carl Sagan believed humans were “obliged” to leave Earth, if only to ensure our survival as a species. The dinosaurs didn’t have a space program, as the space-industry axiom goes, and look where it got them.

But increasingly it seems that it will be a man-made disaster, rather than an asteroid, that leads to our own demise on Earth: Last month, Jeff Bezos, the Amazon and Blue Origin aerospace manufacturing Chief Executive Officer who wants to put humans back on the moon as early as 2024, said that we are “destroying the planet” with heavy industry and climate change, and that humans will “have to go to space if we are to continue to have a thriving civilization.”

But there are less existential reasons for humans to spread out into the cosmos, from a romantic pursuit of interplanetary manifest destiny to the immeasurable reservoirs of frozen water, gold, platinum, and other rare metals locked up in other celestial bodies including the moon. Colonization on Earth, however, especially in pursuit of resources, is colored by a history of genocide, cultural cleansing, and environmental destruction. There is a growing social justice movement that calls for policies to prevent the same fate in space. […]