Moon landings could destroy evidence of life's origins

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Landing spacecraft on the moon could contaminate ancient clues about how life may have originated on Earth, a new study finds.

As NASA continues on with its plan of sending astronauts back to the moon with the Artemis program, researchers are exploring what possible unintended consequences may arise from humans visiting the lunar surface. For instance, Artemis IV will land astronauts near the moon's south pole and the agency has future plans for building a longer-term moon base on the lunar surface, which would require many more trips. And indeed, a new study has found the exhaust from spacecraft involved with these landings could expel enough methane to contaminate the moon's surface — possibly destroying molecules that could help to explain how life may have originated on Earth.

"We are trying to protect science and our investment in space," senior study author Silvio Sinibaldi, the planetary protection officer at the European Space Agency, said in a statement. "Our activity can actually hinder scientific exploration."

While experts have had concerns for some time about how rocket launches on Earth pollute our planet and atmosphere, scientists have only really considered this issue with our own planet. This is especially because we haven't been to the moon's surface in over 50 years; concerns of accidental effects of a lunar landing simply haven't been top-of-mind. That's what makes this new study so important. It points to a potential issue that could mean that future moon landings might actually be detrimental to science.

Life's clues on the moon?

So why do we think the signs of life could be hiding on the moon? It's actually hiding in ice. Dark craters near the moon's poles, which exist in perpetual shadow, hold ancient ice. This ice is thought to contain material from asteroids and comets that smashed into the moon billions of years ago. Trapped in lunar ice to this day, these bits of ancient collisions could include what the researchers describe as "prebiotic organic molecules," or molecules that could have preceded life on Earth.

It's thought that these molecules from asteroid and comet visitors could have sparked life on Earth, and by studying those possibly trapped on the moon, researchers could be looking at the molecules that ended up combining and creating life as we know it.

The molecular history of life on Earth is pretty much nonexistent on our own planet, as it was largely destroyed by the billions of years of changes we've experienced. But the moon has remained mostly unchanged, so these wells of ice are a uniquely-preserved sampling of pre-life molecules.

"We know we have organic molecules in the solar system — in asteroids, for example," Sinibaldi said. "But how they came to perform specific functions like they do in biological matter is a gap we need to fill."

This ice exists in a somewhat fragile ecosystem, so left alone in darkness, this ice isn't going anywhere anytime soon. But with Artemis, NASA is planning on sending crewed landers to the moon's south pole. That might pose a problem. With computer models in this new study, researchers have shown that the methane exhaust from these landers could very quickly and permanently contaminate this ancient ice, destroying the molecular evidence sealed within.

Inside the simulations

In those computer models, the researchers simulated how methane, the main organic component expelled by planned lunar landers, would spread across the moon's surface after a landing at the south pole. While the simulations included the effects of solar wind and radiation, the moon's lack of an atmosphere caused the methane to spread incredibly quickly, reaching the moon's north pole in under two lunar days.

Within one lunar week (which is roughly seven months on Earth), over half the methane was trapped at the moon's cold polar areas, with a whopping 42% of the substance trapped at the south pole compared to 12% at the north pole. This methane could collect in the same cold pockets where ice and ancient molecules have been collected for billions of years, possibly contaminating this finite, scientific evidence.

"Their trajectories are basically ballistic," lead author Francisca Paiva, a physicist at Instituto Superior Técnico in Portugal, said in the statement. "They just hop around from one point to another."

In better news, there may be a way to circumvent some of this methane disturbance. For instance, the study suggests it's possible that by choosing colder landing sites, scientists can avoid having the methane travel as quickly or as far. Additional simulations are needed to better understand how exhaust compounds travel on the moon, however, as well as the risks that this poses for scientific investigations and if there are other materials lunar trips will involve that could contaminate the environment. Above all, the new study's team emphasizes that as we push toward future lunar exploration, it is key to balance our dreams of settling the moon with preserving its priceless history.

"We have laws regulating contamination of Earth environments like Antarctica and national parks," Paiva said. "I think the moon is an environment as valuable as those."

This work was described in a study published last year in the journal the American Geophysical Union.