The question of whether human waste was left on the Moon is common, stemming from the Apollo program when twelve astronauts walked on the lunar surface. Managing human life, including bodily functions, was necessary. The answer is yes: the Apollo missions resulted in a “biological legacy” of human waste left behind at the landing sites. This material, along with other refuse, remains on the Moon today, creating a unique scientific scenario.
Human Biological Waste Left on the Lunar Surface
The Apollo astronauts intentionally left behind nearly 100 bags of human biological waste, including feces, urine, and vomit, across the six landing sites. Waste management in the cramped Lunar Module cabin was difficult, especially given the microgravity of the journey and the one-sixth gravity on the surface. For defecation, astronauts used a Fecal Collection Assembly—a plastic bag taped to the buttocks—which was sealed after use with a germicidal solution.
The primary reason for leaving this waste was the severe weight constraints of the ascent vehicle, the Lunar Module (LM). To ensure a successful return to Earth orbit, crews had to shed every non-essential ounce of mass before lifting off the lunar surface. This included used equipment, food packaging, and the sealed bags of human waste, which were stored in the LM descent stage or tossed onto the surface. By shedding this refuse, the astronauts maximized the weight of the lunar rock and soil samples they collected to bring back to Earth.
How the Lunar Environment Affects Organic Material
The biological material left on the Moon is exposed to one of the most hostile environments in the solar system, affecting its preservation. The lunar surface exists in a near-perfect vacuum, lacking atmospheric pressure or oxygen needed for typical terrestrial decomposition. This absence of air and liquid water prevents biological breakdown by microorganisms like bacteria and fungi, which require these elements to thrive.
Instead of rotting, the material undergoes sublimation, where frozen volatile compounds transition directly from a solid to a gas. Over decades, intense solar and cosmic radiation bombards the lunar surface, breaking down molecular bonds within the organic material and causing gradual chemical degradation. The bags are also subject to massive temperature fluctuations, swinging from 250°F (121°C) during the lunar day to -250°F (-157°C) during the lunar night. These extreme conditions effectively flash-freeze and slowly sterilize the material, creating a unique form of long-term preservation.
Scientific Value and Future Protection of Apollo Sites
The decades-old waste represents an uncontrolled, long-duration experiment in space biology, offering a unique opportunity to study microbial survival in an extraterrestrial environment. The bags contain terrestrial human microbes and DNA exposed to the harsh combination of radiation, vacuum, and temperature extremes for over 50 years. Scientists are interested in retrieving these samples to study if microorganisms have survived in a dormant state or if their genetic material has mutated after prolonged exposure.
This potential for scientific discovery, combined with the historical significance of the sites, has led to protection measures for the Apollo landing zones. NASA has issued guidelines to protect these “heritage sites” from future human or robotic interference. These guidelines recommend creating exclusion zones and buffer areas around the artifacts to prevent disturbance, contamination, or damage from rocket exhaust or dust plumes. The goal is to ensure the waste, the footprints, and the surrounding environment remain untouched, preserving them for historical context and future scientific investigation into the fate of terrestrial life on the Moon.