When planning for a space mission, one of the critical factors to consider is the health of astronauts during their travel to new celestial bodies in the Solar System. Although there are protocols for cleaning and decontamination, microorganisms from our planet have been and will be identified on spacecraft. This raises serious concerns for human safety and planetary protection, especially if these microorganisms can evolve and adapt to their new environment.
Survivors of Hostile Environments
Over the past years, microbiologists have discovered that some bacterial strains can survive extremely hostile environments on Earth and in space. Here on our planet, these microorganisms have been found growing in places with abnormally high amounts of salt, radiation, and extreme temperatures and those with almost no water. One type of bacteria was found living on the space station's exterior, while the other types can grow on meteorite material.
These findings have led to concerns regarding the safety of astronauts traveling to places like Mars. If these pathogenic organisms from Earth were carried to the red planet, either on or in astronauts or the equipment they bring, they could lead to sickness or even death.
Threat in Space Colonization
In a new study, an international team of biologists, radiation specialists, and infectious disease experts has discovered that four types of bacteria can survive exposure to hostile Martian environments. Their findings are reported in the paper "Survival of Environment-Derived Opportunistic Bacterial Pathogens to Martian Conditions: Is There a Concern for Human Missions to Mars?"
Led by Tommaso Zaccaria, the researchers exposed human-infectious bacteria to Mars-like conditions. They created a simulation in a box in their laboratory, complete with cold temperatures, a regolith stand-in, radiation exposure, and a no-oxygen atmosphere.
Four types of bacteria were added: Pseudomonas aeruginosa, Serratia marcescens, Burkholderia cepacia, and Klebsiella pneumoniae. All these bacteria types are harmless to humans but can become pathogenic when stressed.
In the study's first phase, the experts tested how each type of bacteria responded to each simulated condition individually. After that, they subjected all four types to all simulated conditions simultaneously.
Scientists initially thought that regolith or soil imitating the Martian environment would have a toxic effect on thebacteria cellsa and would limit their growth. Surprisingly, however, they found that their simulation had the opposite effect on bacteria.
The researchers discovered variable responses, such as the inability of Burkholderia cepacia to grow in sodium-phosphate-rich soil, which is a possible condition on Mars. The dramatic reduction in water in the simulated environment could have also reduced survivability.
To some extent, however, all four types of bacteria survived when exposed to all the elements they received from the red planet. Three bacteria types stayed for 21 days, with Pseudomonas aeruginosa seeming to reproduce and thrive.
The team concluded that bacteria inadvertently brought to Mars could pose serious health threats to astronauts. This can worsen if the microorganisms mutate to survive the hostile conditions better.
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