One Small Step for Man, One Giant Leap for Moon Microbes? Interpretations of Risk and the Limits of Quarantine in NASA's Apollo Program

As NASA prepared to land astronauts on the Moon in the 1960s, scientists and federal officials came to fear that they could bring lunar microorganisms back to Earth, with potentially grave consequences for human, plant, and animal life. To prevent this "back contamination," representatives from NASA and a network of federal departments and services developed a protocol to quarantine astronauts, equipment, samples, and spacecraft exposed to lunar dust. Yet although NASA assured policy makers and an anxious public that it had implemented impermeable safeguards against the escape of lunar microorganisms, it had in fact prioritized likely risks to astronauts over unlikely risks to American society. To a degree previously unknown, the Apollo quarantine protocol suffered from numerous containment breaches that would likely have exposed the terrestrial biosphere to contamination-had lunar microorganisms actually existed.