Scientists Warn of Bacterial 'Alien Invasion' Caused by Space Missions

Scientists have warned of a potential "alien invasion;" the risk doesn't come from extraterrestrials arriving in their spacecraft, but from bacteria hitching a ride home on ours.

McGill University researcher Anthony Ricciardi and colleagues warn that our increased activity beyond the limits of Earth's atmosphere brings with it the danger of micro-bacterial contamination. In a paper published in the journal Bioscience, the authors address the risk of biological contamination from space and highlight the need for biosecurity measures to limit the threat.

The team points out that despite considerable microbial caution among space agencies "bacterial strains exhibiting extreme resistance to ionizing radiation, desiccation, and disinfectants" have been discovered in NASA clean rooms used for spacecraft assembly.

Scientists were warning as early as 2013 that extreme radiation-resistant microorganisms that can survive the extreme conditions of space could jeopardize sample return missions, and could even ruin our chance of detecting life elsewhere in the solar system.

As we haven't discovered alien life, even bacterial life, the risk may seem negligible. But researchers have discovered strains of bacteria in space completely unknown on Earth. These have evolved from Earth bacteria on the International Space Station, a unique and isolated environment.

The possibility of introducing bacteria to space environments in this way and then bringing their evolutionary offspring home means researchers' concern isn't just for Earth. They warn of bacteria being carried to alien worlds such as Mars and prospering there.

"For a mission to Mars, for example, the risk of survival and proliferation of introduced terrestrial organisms is thought to be low and an even more negligible risk might be ascribed to the event in which a living organism from Mars is transported to Earth, subsequently released, and colonizes its new environment," they added.

The authors say such biological invasions could be compared to extreme natural or technological disasters such as major earthquakes or nuclear meltdowns. This is because though rare such "invasions" could have dangerous consequences.

That means, the researchers wrote, the risks merit unique safeguards. They added: "Protocols for early detection, hazard assessment, rapid response, and containment procedures currently employed for invasive species on Earth could be adapted for dealing with potential extraterrestrial contaminants."

The authors point out that such "alien" invasions aren't unheard of, unspoiled regions of our planet have been contaminated by excursions from other regions.

"Biological invasions—the human-assisted spread of organisms into novel environments, in which such species are most often termed "alien"—are a threat to ecosystem sustainability and human well-being," they wrote. "Owing to human activities, the rate of spread of alien microbes, invertebrates, vertebrates, and plants across the planet is unprecedentedly high with no sign of saturation."

The authors point out that even the remotest alpine, polar, and deep ocean regions of the Earth have been invaded with recent evidence showing that humans have inadvertently introduced drug-resistant enteric bacteria into the Antarctic ecosystem, which has gone on to infect wildlife such as seabirds and seals.

And humans are already contaminating space.

One striking example of humans launching an "alien invasion" of another world, albeit inadvertently, happened in 2019 when Israel's Beresheet mission crash-landed on the moon. The craft was carrying tardigrades, microscopic animals which are known for their ability to survive extreme conditions. This includes the extreme heat and cold, as well as the vacuum of space and heavy-duty doses of radiation.

Tests conducted after the crash exposed the animals also referred to as "water bears" to the kind of extreme velocities they would have experienced in the crash. These tests showed that, despite their hardiness, the microscopic creatures were unlikely to have survived the impact on the lunar surface.

Concluding their paper the authors empathize the need for greater collaboration between invasion biologists and astrobiologists. They wrote:

"[This] would enhance existing international protocols for planetary biosecurity—both for Earth and for extraterrestrial bodies that could contain life."

Bacterial Invasion.
The Earth against a sea of bacteria. Scientists have warned that space agencies must be aware of the potential contamination of our planet with bacteria from space. Getty