This is the 38th in an exclusive series of 50 articles, one published each day until July 20, exploring the 50th anniversary of the first-ever Moon landing. You can check out 50 Days to the Moon here every day.
In March 1966, a group of 14 scientists, working on behalf of NASA, produced an astonishing report about a delicate topic: How to go to the Moon without polluting the Moon.
The conclusion: You can’t.
Simply landing a spaceship and astronauts on the Moon was going to bring with it an astonishing fog of alien pollution.
The lunar module’s rocket engine, hovering the spaceship down from orbit and running until the moment the lunar module touched the surface, was burning almost 1,000 pounds of fuel every 30 seconds, and spraying its exhaust across the Moon nonstop.
The lunar module itself vented both gases and water vapor, and when the astronauts got ready to leave for a Moon walk, they emptied the entire cabin—humidity, air, any particles floating in the atmosphere—right out onto the Moon.
When the lunar module blasted off to head for orbit, the ascent engine would again spray the surface of the Moon with chemicals.
The report, which is 206 pages, considers not just all that material, settling in a fine glaze across the lunar surface, but whether any of those chemicals, particularly the hot exhaust gases, would in turn chemically react with lunar soil and create different reaction products—material that shouldn’t be confused, if it were collected, with “native” lunar material.
Even the spacesuits themselves were a constant source of contamination, because they leaked and vented, including what the report delicately describes as “flautus gases.”
Yup: Astronaut farts contaminated the scientific purity of the Moon, although their quantity was small, compared with what was coming from the lunar module’s engine, for instance.
“The importance of spacesuit leakage is apparent since the astronaut will closely approach, and may possibly even come in contact with, the samples he is collecting,” the scientists wrote. “Therefore, every sample collected by an astronaut will have had spacesuit leakage squirted at it.”
We were going to the Moon, in part, to bring home pristine samples of Moon rock and soil to analyze and understand. No scientist wants to study Moon rocks coated in an unintended glaze of rocket fuel or seasoned with organic molecules from a Moon walker. The scientists’ analysis is a reminder of the 10,000 problems that NASA had to solve to get to the Moon, how complicated they were, and also how demanding simply finding all those problems was in the first place.
In this case, it would turn out, this wasn’t a solvable problem.
The key would turn out to be minimizing the contamination, and also understanding what it was—all the elements of Earth we had brought with us—so when samples came back, scientists would understand what they were looking at.
As that report, more than three years before the first Moon landing, put it, “A sample that might be considered hopelessly contaminated by a biologist . . . could be rated as being free from contamination by a geologist.” Unintentional contamination of bacteria from the exhalations of the astronauts might make it look to a biologist like there was life on the Moon; those same few organic molecules would be irrelevant (or undetected) by a geologist trying to understand how the Moon formed.
NASA, in fact, went to extraordinary efforts to protect Moon rock samples. They were put in their containers by astronauts outside the lunar module, in the vacuum of the Moon’s surface, and those containers were closed outside and had triple seals. They weren’t opened until they were in a special lab NASA had constructed at the Manned Spacecraft Center in Houston, the Lunar Receiving Laboratory, where they were unsealed in vacuum chambers to try to preserve their uncontaminated state. (After a couple of missions, scientists concluded that the vacuum system was too cumbersome, and samples were unsealed inside chambers filled with purified nitrogen gas for easier handling.)
The challenges were well understood at the time. Says a NASA history of the processing lab, “Its personnel were given the impossible task of creating a perfect system for the processing of lunar materials.” And that was back on Earth.
Two things ended up being true about the science done with Moon materials. First, the samples collected transformed scientific understanding of the formation of the Earth and the Moon. The Apollo missions changed how geologists and astronomers understood the relationship between the Earth and the Moon, the Moon’s composition, and the dynamics of the solar system. The Apollo 15 astronauts brought back a rock, nicknamed the Genesis Rock, that at 4.1 billion years old, is one of the oldest rocks humans have discovered anywhere.
It was also true that the task of bringing back completely pristine samples was impossible. The Moon, for instance, has a very faint atmosphere. The exhaust from a single lunar module’s descent engine contained as many molecules, the report noted, as the entire lunar atmosphere. Which is to say, each of the six Moon landings delivered to the Moon enough gas to fully replace the existing Moon atmosphere. And as the lunar module approached the Moon’s surface, that exhaust was powerful enough to spray lunar debris in all directions for many miles. Apollo 12 landed less than 600 feet from where Surveyor 3 had landed, a triumph of Moon navigation. But as the lunar module landed, its rocket exhaust was so powerful, it sandblasted the equipment on Surveyor 3 that was facing the lunar module.
The astronauts also left a fair amount of debris on the Moon on purpose: Equipment they couldn’t take back, or didn’t want to take back, to orbit and then to Earth. Indeed, they discarded everything they could to save weight, including their Moon-walk boots and their life support backpacks, but also, of course, the lower stages of six lunar modules, and three perfectly good lunar rovers, the Moon dune buggies. A straight-faced NASA inventory of the material left on the Moon also notes items like earplugs and 96 bags of human waste.
The authors of the original report had figured out the complexity of the problem and conveyed a sense of urgency about humans bringing their own contamination to the Moon—along with a warning for all kinds of future interplanetary exploration.
Even with care, they wrote, “The door to entire fields of experimental lunar research may close forever after the first manned mission.”