One of the strangest experiments in astrobiology has already been running for more than half a century. Nobody designed it, no instrument has monitored it, and its samples were left beneath lunar modules as rubbish.
Across Apollo 11, 12, 14, 15, 16 and 17, astronauts discarded human waste and other material before leaving the Moon. The commonly cited total is 96 bags and containers. The oldest have been at Tranquility Base since July 1969, exposed to 57 years of vacuum, radiation and lunar day-night cycles.
The immediate question is irresistible: could anything in them still be alive? The careful answer is that probably nothing is, but nobody has tested the actual material. That gap is why researchers have identified an Apollo jettison bag as a serious recovery target. Even a completely sterile sample could measure how cells, DNA and other biological traces decay in a real extraterrestrial environment.
The number 96 needs a label attached
The figure has travelled widely through popular accounts, usually described as 96 bags of urine, faeces and vomit. It is better treated as a commonly repeated aggregate than as a neat NASA inventory of 96 identical faecal bags. Apollo waste came in several kinds of packaging, and the mission record uses several different names.
Individual faecal and emesis bags were small collection devices. Urine was handled separately. Larger nylon sacks, known as JETT or jettison bags, gathered cabin refuse before it was carried through the hatch. One large sack could enclose smaller waste bags alongside food wrappers, empty water containers, wipes and equipment that no longer had to fly.
NASA’s Apollo Lunar Surface Journal history of the jettison bag says the crews generally took one full sack outside at the beginning of each moonwalk. On every landing except Apollo 11, another went out near the end with the portable life-support backpacks. The later missions used some empty sacks to contain dust on spacesuit legs during rest periods.
This distinction matters because the large white bundle visible beneath Eagle in Neil Armstrong’s first surface photograph is a mixed rubbish sack, not a transparent label for one bowel movement. It also means that retrieving “one bag” could mean sampling a layered container holding several materials with different biological histories.
Apollo left mass so its astronauts could leave the Moon
The lunar module was a tiny cabin and a brutally mass-limited flying machine. Its descent stage remained on the surface while the upper ascent stage carried two astronauts back to lunar orbit. Anything unnecessary for that climb was more useful on the ground than aboard.
A NASA technical history of the lunar module notes that it had no installed toilet or designated toilet area. The crew used urine and faecal collection bags, and body waste was left on the surface before ascent to reduce mass and contamination risk.
The faecal system was more engineered than the phrase “plastic bag” suggests, but not more dignified. An adhesive rim held an inner bag in place. After use, the astronaut added wipes, sealed it and manually mixed its contents with a germicidal liquid. The inner package then went into an outer bag.
NASA’s detailed Biomedical Results of Apollo account identifies the germicide as a mixture based on two phenol compounds. It was intended to inactivate microbes and limit gas production during storage. That treatment is an important complication for any modern survival experiment. Researchers would be testing the combined effects of biocide, drying, packaging and the Moon, not radiation and vacuum alone.
Jettison sacks also solved a housekeeping problem. NASA’s history describes an empty one as roughly 101 centimetres long and 70 centimetres wide. Filled in the cramped cabin, it could become the size of an eight-year-old child. Astronauts pushed the sacks down the ladder and often kicked them beneath the descent stage, where they would not be caught directly by the ascent engine’s exhaust.
Why scientists want the rubbish back
In a 2019 study in the journal Astrobiology, Andrew Schuerger and colleagues modelled what happened to microbial contamination carried by dozens of spacecraft that landed or crashed on the Moon. They considered ultraviolet light, vacuum, high temperatures, thermal cycling and ionising radiation, with different assumptions for exposed, shallow and deeply protected surfaces.
Their forecast was not optimistic for living Apollo stowaways. Exposed spacecraft surfaces were expected to become sterile after a single lunation. Deeply embedded microbes could last longer because surrounding structure slowed heating and reduced radiation, but the model predicted that hardware arriving between 1959 and 1976 would be free of viable Earth microorganisms by 2030.
Yet the same paper placed Apollo’s nylon jettison bags at the top of its Apollo-era recovery list. There is no contradiction. Human waste, used sleep restraints and air-filtering lithium-hydroxide canisters should have started with richer and more varied microbial populations than the outside of a robotic lander. Bags tucked beneath a descent stage may also have escaped the worst thermal cycling.
A return would therefore test a demanding prediction at the place where survival had some of its best plausible advantages. Finding no viable cells would constrain the upper limit on survival. Finding even a handful, after contamination had been convincingly excluded, would show that the model missed a protective combination of material, geometry or microbial state.
Viability is only one outcome. Investigators could look for culturable organisms, intact or fragmented DNA, proteins, lipids and chemical changes in the packaging. They could compare sun-facing and shaded layers, measure radiation damage and ask whether different biological signatures disappear at different rates. Sterile waste can still contain a readable history.
The Moon is harsh, but exposure is not uniform
The six Apollo landing sites are at low lunar latitudes, not in the deep cold of a permanently shadowed polar crater. Each location experiences a day-night cycle lasting about 29.5 Earth days. For roughly two weeks the Sun heats exposed surfaces; for roughly two weeks darkness allows them to cool.
Solar ultraviolet light can damage DNA directly. Vacuum removes available moisture and stresses membranes. Energetic particles gradually break chemical bonds, while repeated heating and cooling fatigue both cells and the plastics surrounding them. There is no stable surface liquid water to support metabolism. Any survivor would almost certainly be dormant, not feeding or reproducing inside a lunar colony.
Still, a microbe’s actual dose depends on centimetres and layers. A spore on the outer fabric is not equivalent to a cell embedded in dried material, sealed behind inner and outer bags, wrapped inside a larger sack and shaded by a spacecraft. The precise orientation of a sack, its tears, dust cover and distance from the lander could decide which stress dominated.
That patchiness has gained fresh relevance. SpaceDaily recently examined how a human-associated black fungus emerged as the most ultraviolet-resistant organism in a new Moon-survival study. The 2026 work modelled small shaded niches near the lunar south pole where terrestrial cells might remain viable for a day or longer.
NASA’s account of that study is explicit that survival does not mean growth. Its polar shadows are also not direct substitutes for Apollo’s equatorial sites. Together, the studies make a narrower point: “the lunar environment” is not one dose, and shielding can change the time it takes to kill a cell.
Surveyor 3 showed how easily the answer can be spoiled
Apollo has already produced one famous microbial-survival claim. In November 1969, Apollo 12 astronauts walked to the robotic Surveyor 3 lander, cut away its television camera and returned it to Earth after the machine had spent about 31 months on the Moon.
Laboratory workers later recovered Streptococcus mitis, a bacterium associated with the human mouth and respiratory tract. The result was presented as evidence that a terrestrial microbe had survived on the Moon. Later scrutiny of photographs and handling procedures made accidental contamination in the terrestrial laboratory the more persuasive explanation.
NASA’s current planetary-protection history retains both sides of that episode. It is a useful warning for an Apollo waste recovery. A living organism found in a returned bag would be scientifically meaningful only if the collection system, return container and receiving laboratory could show that the organism was not introduced during retrieval.
A strong protocol would sample the exterior before opening the package, include sterile blanks and seal the material at the lunar site. It would record microbes associated with the recovery crew, suits, tools and spacecraft. Genetic sequencing could help trace a contaminant, but DNA alone cannot reconstruct every handling error. The chain of custody would be part of the experiment.
A baseline before the Moon becomes busy again
Retrieving an Apollo jettison bag would not be a lunar cleanup project. The material is part of a protected historic landscape, and disturbing any landing site would require careful archaeological as well as scientific planning. Nor would one sack represent every Apollo mission. Six sites, different stay lengths and inconsistent patterns of shade produced six sets of conditions.
The experiment matters because human contamination is about to become more complicated. Crewed landers, rovers, suits and habitats will shed cells and biological molecules continuously. At the south pole, where cold traps preserve water and organic chemistry, new terrestrial material could make later measurements harder to interpret.
The Apollo bags preserve a much simpler event: known humans, known materials, known landing dates and decades of exposure with no later visitors. Their contents were treated with germicide and their exact inventory is imperfect, but those flaws are documented parts of the sample rather than reasons to ignore it.
The most likely result is not a revived bacterium. It is a boundary: how thoroughly the Moon erased viability, what molecular traces remained, and how much protection a few layers of nylon, plastic and dried material supplied. After up to 57 years, even a bag containing nothing alive could answer a living question about how carefully humanity must carry itself onto other worlds.