Mars Mission Risk: Fungus Survives Space Travel, Threatens Contamination

Top Summary

• What happened: Researchers discovered that certain types of fungi found in spacecraft cleanrooms can survive harsh conditions mimicking space travel and Martian environments.
• Why it matters: This discovery suggests a higher risk of forward contamination of Mars than previously thought, potentially impacting future scientific studies.
• What changes for people: Current planetary protection strategies may need to be updated to account for the resilience of these fungi.
• Who is affected: NASA, ESA, and other space agencies involved in Mars missions, as well as scientists studying Martian environments.

The Fungal Frontier: Spacecraft Cleanrooms and Microbial Stowaways

Space probes undergo assembly in specialized cleanrooms. The goal is to minimize contamination by terrestrial microbes.

This reduces the risk of bacteria or fungi hitching a ride on landers and rovers. Consequently, it also prevents the inadvertent contamination of extraterrestrial environments.

Samples returned from other celestial bodies are also handled in these facilities. They must remain uncontaminated during analysis and storage.

Sterilization Protocols vs. Microbial Resilience

NASA and ESA cleanrooms undergo regular treatment with chemical disinfectants. They are also maintained under positive pressure to keep them sterile.

All items entering these environments are sterilized using ultraviolet light and heat treatments. Personnel wear specialized protective suits.

Yet, some microbes exhibit remarkable resistance to these measures. Several mold species have been detected, including in the "Perseverance" rover's cleanroom.

Extreme Survival: Fungi vs. Martian Conditions

Researchers tested 27 fungal strains from spacecraft assembly facilities. They also included an ISS-derived strain under combined stressors.

These stressors included Mars-like UV irradiation, temperature extremes (-60 to 150 °C), desiccation, and an oxidizing regolith simulant.

They also used prolonged exposure to ionizing radiation.

Aspergillus calidoustus: The Ultimate Survivor

Aspergillus calidoustus displayed exceptional resilience. This was observed among all the tested organisms.

It maintained viability after extended UV exposure (up to 1,440 minutes), Mars-analog atmospheric conditions, and multi-month radiation doses.

These radiation doses were comparable to those in interplanetary cruise environments. Survival decreased only under extreme cold and radiation stress combined.

Forward Contamination: A Reassessment of Risk

Researchers state that certain cleanroom-associated fungi could survive the entire sequence of launch, interplanetary transit, and Martian surface conditions.

 

This suggests a significant theoretical risk of forward contamination, despite the strict sterilization protocols in facilities operated by NASA and ESA.

 

While actual Mars contamination remains unlikely, researchers highlight a gap in current planetary protection strategies. These strategies have historically focused on bacterial spores rather than fungal resilience.

Planetary Protection: Adapting to New Threats

The research emphasizes the need to re-evaluate planetary protection measures.

• Current protocols primarily target bacterial spores.
• Fungal resilience requires a new approach.

 

Current strategies may not be sufficient to prevent fungal contamination on Mars.

 

What to Watch Next

Future research will likely focus on identifying more resilient fungal species and developing improved sterilization techniques. The findings could lead to revised planetary protection guidelines for upcoming Mars missions, ensuring the integrity of future scientific discoveries.