Humanity's spacecraft are already searching the outer solar system for signs of microbial life, and the scientists and policy scholars who track these missions believe discovery is no longer a matter of imagination but of timing. What remains unresolved is not the science but the architecture of human response — the treaties, institutions, and norms that would govern a find of such magnitude do not yet exist in any meaningful form. The 1967 Outer Space Treaty, written when life beyond Earth seemed a distant abstraction, offers no guidance on biosecurity, ownership, or the geopolitical competit