In five articles and an introduction, this dissertation contributes to the emerging field of space ethics by exploring questions about environmental ethics in outer space, considered from a long-term perspective.

In particular, it examines directed panspermia, which refers to the deliberate introduction of rudimentary lifeforms onto uninhabited celestial bodies in order to initiate biospheres beyond Earth. Such an act, if possible, could constitute humanity's most significant biological cosmic footprint.

The central claims of this study are the following. Given uncertainty surrounding life beyond Earth, and given the fact that life on Earth will eventually end, we have compelling reasons to use directed panspermia as a way to safeguard life originating on Earth—either to efficiently promote value, or to conserve what is valuable. But there are major objections to this proposal, including the risks of interfering with potential indigenous life at a target planet and propagating suffering if, over time, sentient beings arise on the seeded planet. The objections’ strength depends on unresolved empirical and moral uncertainties. As a result, directed panspermia may turn out either extremely good or extremely bad. In light of this difficult choice, I ague for caution regarding biological contamination.

Along the way I also consider two other objections to directed panspermia: appeals to the “unnaturalness” of planetary seeding, and the values of abiotic environments. While these factors may impact the permissibility of exoplanetary seeding, I argue that they are not as weighty as concerns about interference and suffering, especially when we measure them against the potential value of preserving the story of Earthoriginating life in the cosmos