On the Moral Permissibility of Terraforming

Terraforming is a process of planetary engineering by which the extant environment of a planet is manipulated so as to produce an Earth-like ecosystem. This paper explores the ethical questions about the exploration of space and the exploitation of space resources that arise in the consideration of terraforming. I argue that space advocacy (including the pursuit of terraforming) and environmentalism are mutually beneficial endeavors. I show that the moral status of terraforming a planet, at least under traditional anthropocentric and non-anthropocentric positions, is sensitive to whether life exists on the candidate planet. I also examine several attempts—due to Holmes Rolston, Keekok Lee, Alan Marshall, and Robert Sparrow—to show that terraforming a planet would be impermissible even if the planet was not home to life. I argue that no attempt provides compelling reasons for the supposition that terraforming is morally impermissible.