A robust and growing commercial space sector is moving ahead at warp speed. While the industry today primarily offers satellite and launch services, tomorrow will bring manufacturing, research and development, resource extraction, and space tourism. What do these developments mean for the earth’s biosphere, as well as for the environments of other celestial bodies finally within humanity’s reach? This is the role of planetary protection, the principle of safeguarding both terrestrial and extraterrestrial environments from humanity’s propensity for introducing pollution into any habitat. Planetary protection’s goals remain constant, but the methodology is undergoing an evolution. We are witnessing a move beyond a prophylactic approach to planetary protection analogous to the precautionary principle, to one based in the type of cost-benefit analysis so familiar to legal practitioners in the United States. This shift is informed by expediency and advances in technology and scientific understanding, as well as growing realization that the regulatory gap—which private commercial actors slip through—must be addressed.