When is it OK to kill an alien life-form?
In the movies, the answer is usually pretty simple: It’s OK in self-defense, especially if it inspires a rousing speech about human exceptionalism. But in the real world, the choice is neither straightforward nor abstract. Many missions to neighboring worlds could, accidentally or intentionally, disrupt extraterrestrial life. Under what conditions would the loss of a few aliens—admittedly, presumably microbes—be acceptable?
The range of views on this issue are diverse, fascinating, and essential to acknowledge as we pursue detections of life on other planets. Missions currently on Mars, as well as forthcoming missions to outer solar moons, including Jupiter’s moon Europa and Saturn’s