Biological threats in space represent a major challenge for human space exploration. This blog provides an overview of biological threats to spacecraft and astronauts, as travel to increasingly distant planets continues to grow.
What are we talking about?
As space exploration and research progresses, the possibility of encountering biological threats in space becomes a growing concern. These threats could come from micro-organisms (viruses, bacteria, fungi, etc.) that could harm human health and the environment.
Micro-organisms may exist naturally in extraterrestrial environments, having evolved to survive in extreme conditions such as extreme temperatures, high radiation levels and lack of water. The intentional or accidental introduction of micro-organisms by man can occur through the contamination of spacecraft or equipment used for space exploration, or through the release of waste from space habitats.
Biological threats in space can be significant for human health and extraterrestrial ecosystems. Micro-organisms that harm humans can cause infections, allergies, and other health problems. In addition, the introduction of new organisms into extraterrestrial environments can disrupt existing ecosystems and modify natural processes.
With the increasing number of space missions and expeditions, there is growing concern about potential biological threats.
Many reasons to study space bacteria
Threats to human health :
The microgravity environment of space can weaken the immune system, making astronauts more vulnerable to infection;
What’s more, microorganisms that are harmless on Earth can become virulent in space due to mutations caused by exposure to radiation or other environmental factors.
The risk of contamination :
Spacecraft returning from missions can carry micro-organisms capable of surviving in the harsh conditions of space. If these micro-organisms are not properly contained and decontaminated, they can threaten terrestrial ecosystems and public health..
The origins of life on Earth and on other planets :
Microorganisms found in extreme environments such as space may exhibit unique genetic adaptations that could shed light on the evolution of life on Earth and the possibility of extraterrestrial life.
Biological samples in space
Between the 1950s and 1960s, the USA and the Soviet Union launched several missions that carried biological samples into space, including bacteria, viruses and fungi. The aim of these multiple missions was to study the effects of microgravity and radiation on living organisms. However, they also raised concerns about the possibility of contaminating other planets or spacecraft.
When humans were first sent into space, it was realized that there was a risk of contamination of individual crew members by a pre-existing micro-organism.
Concerns were heightened between 1968 and 1972 with the American Apollo missions to the moon. The possibility of sending a person to a celestial object changed the way scientists viewed biological contamination in space.
To address these concerns, NASA developed strict protocols to prevent biological contamination during manned missions. These protocols included rigorous cleaning and sterilization of the spacecraft, quarantine of the crew prior to launch, and monitoring of the crew’s health during the mission.
One incident put scientists on alert when Appolo XII astronauts brought back with them the Surveyor 3 camera deposited on the moon 2 years earlier. It was contaminated with a strain of Streptococcus mitis! It was then assumed that the strain had been brought from Earth and had resisted on the moon for 2 years before being brought back with the camera.
In fact, the contamination of the camera occurred during handling after the return!
Another question arose when the ALH84001 meteorite from Mars was found in the Antarctic with fossilized bacteria on its surface. This discovery is disputed, but the question of contamination of the earth by micro-organisms from outer space remains.
Modern space missions
Various space agencies are collaborating: NASA, ESA, ROSCOSMOS (Russia), CNSA (China), Space X and others.
Microorganisms found on the ISS (surfaces, air filters, water systems, etc.) have been identified by DNA sequencing (1271 isolates).
Mars Science Laboratory (MSL): MSL is a NASA mission that landed the Curiosity rover on Mars in 2012. The mission also includes several experiments to study the effects of radiation on living organisms.
ExoMars: this is a joint ESA and ROSCOSMOS mission to search for signs of past or present life on Mars. One of the mission’s main objectives is to understand how life can survive in extreme environments like Mars.
The BioSentinel mission: scheduled for launch in 2024. It will send a small spacecraft equipped with yeast cells into deep space to study the effects of cosmic radiation on living organisms. The yeast cells will be genetically modified to detect and report radiation exposure levels, providing valuable data for future manned missions beyond low-Earth orbit.
Bion-M: a series of Russian space missions to study the effects of microgravity and other spaceflight-related factors on living organisms.
The space nations have signed an agreement regulating “forward contamination” and “backward contamination”.
Forward contamination: this is the “unintentional transfer of terrestrial organisms or biological material from Earth to another celestial body, such as a planet or moon”. Spacecraft carry micro-organisms that can contaminate the target environment. If these organisms survive and proliferate on another celestial body, they could interfere with scientific research and compromise the search for extraterrestrial life.
Retro-contamination, on the other hand, refers to “the potential contamination of the Earth by extraterrestrial organisms or biological material”: samples taken from another celestial body are returned to Earth for analysis. If potentially dangerous micro-organisms or other biological entities are present in these samples, they could endanger terrestrial ecosystems and human health.
Can a pathogen survive in space?
Outside the vessel, everything depends on its resistance to extreme temperatures and ionizing radiation (for example, herpes simplex is resistant). The absence of atmosphere also causes micro-organisms to desiccate.
Inside the vessel, microgravity and radiation can modify microbial physiology and gene expression. Experiments on Salmonella Typhimurium and S. aureus have shown that strains in space gain in pathogenicity and antibiotic resistance.
To avoid contamination of extraterrestrial environments, landers are systematically sterilized.
Fungi are also closely monitored, as they often resist extreme cultivation conditions (temperature, pH, radiation, desiccation). Fungal spores are also capable of growing on air filters. They can also spoil food and synthesize dangerous mycotoxins.
Viruses also represent a real danger, since their propagation is favored in closed enclosures where air is poorly recycled. Infectious viral diseases are easily transmitted in enclosed spaces, all the more so as, as we saw earlier, the immune systems of personnel are weakened.
As for unknown micro-organisms coming directly from space, many researchers in the scientific community believe that there is little chance that we will ever find life in our solar system. However, it is essential to be aware of our lack of knowledge about pathogens from other worlds.
The presence of Earth micro-organisms in a space shuttle can be dangerous, as they contaminate each other, alter air filtration, spoil food and increase the circulation of viruses in a closed environment. Illnesses are also more easily transmitted among astronauts who are generally immunocompromised due to radiation. Radiation also promotes gene rearrangement and the emergence of bacteria with increased pathogenicity and a modified antibiotic resistance profile.
Micro-organisms brought into an extraterrestrial environment could also modify the environment, potentially interfering with the legitimate search for life on the colonized planet.
Retro-contamination with micro-organisms unknown to the extraterrestrial environment could also prove dangerous if their pathogenicity is completely unknown.
For us, this is hardly conceivable at the moment, but we need to be able to react to any eventuality.
Biological threats and growth in space (Sincavage & Muehlfelder & Carter).