Between the hit movie “Project Hail Mary” and the real-life lunar journey of Artemis astronauts, it’s been a good season for space. Space exploration is a gripping human adventure – laden with both possibility and risk.
As NASA plans for a crewed mission to Mars in the 2030s, the high stakes are becoming concrete. NASA’s Planetary Protection program works on the two-fold risk of “forward” and “backward” contamination. How can we limit our contamination of other planets? And how can we prevent bringing potentially harmful life forms back home?
To address those questions, scientists have turned to an unlikely place: Carlsbad Cavern.
Joe Hoberg is a PhD student in geobiology at New Mexico Tech. His master’s research was a collaboration with NASA’s Planetary Protection.
“And so the goal then isn't necessarily to prevent contamination,” Hoberg said, “but it's to control for it. If we see it, how early can we see it? And so that's what my work was doing. But I can't go to Mars, sadly. We do the next best thing, which is to take Earth analogs.”
Apollo-era astronauts trained in West Texas – using its extreme desert environments as an analog for the Moon. Caves are another extreme environment, where, even without light, microbial life exists. If there’s life on Mars, it’s apt to be similar to the bacteria found in the “oligotrophic” – or very low-nutrient – conditions of caves.
Contamination introduced by astronauts could disrupt existing Mars life forms. But astronauts might also think they’ve identified life on the Red Planet, when in fact they’re detecting bacteria they introduced.
Even in high-tech clean rooms, scientists can’t completely eliminate contamination; we simply shed too many bacteria. But if astronauts can detect contamination, they can understand their impact and distinguish it from extraterrestrial life.
To refine such detection, Hoberg deployed batteries of instruments in multiple Carlsbad Cavern locations, including the Big Room, which thousands of visitors tour daily, and the Mystery Room – an isolated recess closed to visitation. Hoberg’s months-long study included a second extreme environment – highly acidic hot springs in Northern New Mexico’s Valles Caldera.
The devices tested for bacteria, but also for organic contaminants – like sunscreen ingredients – and inorganic human-sourced materials, like microfibers and microplastics. With advances in genetic analysis, Hoberg was able to test RNA and DNA from hundreds of bacteria samples.
“Back in the early stages of the 90s to sequence just one genome from the human body was hundreds of thousands of dollars,” Hoberg said. “Now it's like we send off batches of samples for sequencing. You get all this information back in about six weeks. It's incredible.”
Hoberg could confidently identify a quarter of the bacteria as human sourced. Even in the remote Mystery Room, he detected all types of contaminants – including microplastics. It underscores the ubiquity of human impacts.
Hoberg’s was a “pilot study,” he said – there’s much more to be done. And the research has implications on Earth, as well as in space.
As in other “show caves,” visitation at Carlsbad threatens a fragile cave ecosystem. With a more nuanced understanding of human contamination, cave managers could mitigate those disturbances.
“Hopefully we can use Carlsbad as a way to pilot this new area of cave conservation research,” Hoberg said, “and build it into some really important stuff that can be applied to all show caves and all caves everywhere.”
Since Hoberg’s research, Trump administration cuts have reduced NASA staff by 20 percent. Planetary Protection’s future is uncertain. But if Americans reach Mars in the coming years, we’ll know that, as with the Apollo Moon landings, our region is part of the cosmic story.
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