The era of space exploration brings new risks. Because what if the earth is infected by extraterrestrial micro-organisms, or vice versa?

Hundreds of flying saucers containing three-eyed green aliens invading our Earth; it sounds like the ominous plot of a science fiction movie. Still, researchers warn that we should prepare for alien invasions. And okay, the danger probably doesn’t come from little green aliens. But that our earth can become infected with extraterrestrial microbes, or that we ourselves infect other planetary celestial bodies with terrestrial ones, is according to a new study a real concern.

unlock space

In the meantime, countless spacecraft have already been sent into the universe. Some have landed on the Moon and Mars, others are flying to distant asteroids. And the idea is that in the near future we will open up the space further. Not only are manned space travel on the horizon, NASA, among others, plans to visit many more celestial bodies in our vast solar system. And who knows what we’ll find on these exotic worlds… “The search for extraterrestrial life is an exciting undertaking that could lead to a huge discovery in the not-too-distant future,” researcher Anthony Ricciardi said in an interview with Scientias.nl. “In light of these increasing space missions – including those that involve taking samples back to Earth – it is critical to minimize the risks of biological contamination in both directions.”

The danger

There is a danger that samples brought from other celestial bodies to Earth harbor certain unknown microbes. And when these get into our world, they can cause a serious problem for ecosystems or our own human well-being. The other way around is also the case; there is a chance that terrestrial microbes will hitch a ride on spacecraft and land on other celestial bodies. And of course you don’t want to deposit terrestrial bacteria or fungi there that will make life miserable for possible aliens or – perhaps worse – be mistakenly mistaken for aliens at a later stage.

Insular ecosystems

According to Ricciardi, it is therefore important that we handle other celestial bodies that may harbor life. “One of the insights from invasion biology is that so-called ‘insular ecosystems’ – ecosystems that have evolved in isolation, such as Hawaii, Australia and Antarctica – are very vulnerable to the effects of introduced alien species,” explains Ricciardi. “Biological invasions have often been devastating to the plants and animals that have evolved in these ecosystems. We therefore argue that planets and moons that may contain life should be treated as if they were insular ecosystems.”

Moon and Mars

Incidentally, there is already a chance that terrestrial microbes dwell on the moon and Mars. Even though strict measures are taken to ensure that once a spacecraft goes into space, it harbors as few microorganisms as possible, it may well be that some smart people have hitched a ride. “Mars has been visited by more than two dozen spacecraft in recent decades,” Ricciardi said. “And since microbes have been found in the clean rooms in which spacecraft are stationed, it is not inconceivable that some organisms have been deposited on the red planet. It is also conceivable – though unlikely – that some of them survived. So should astrobiologists discover life on Mars, they should be able to distinguish real, native organisms from those accidentally traveled on previous space missions.”

More about clean rooms
Many spacecraft spend a large part of their time here on Earth in a so-called clean room. Strict measures are taken in this space to ensure that once the spacecraft goes into space, it harbors as few microorganisms as possible. The relevant measures that are taken in and just outside the clean room to avoid these doomsday scenarios vary widely. For example, it is ensured that the clean room is very dry and contains as few nutrients as possible for bacteria or fungi. People are also not allowed to enter the clean room until they have put on a special suit, so that bacteria living on and in them cannot jump over to the spacecraft. Still, it seems that some tenacious specimens manage to survive even these extreme conditions.

It means that in all our enthusiasm for the search for extraterrestrial life, we mustn’t forget the dangers of biological contamination. Because if we find life on Mars and take it back to Earth for further analysis, it could have far-reaching consequences if not handled with care. Which life forms should we be most concerned about? “We can only speculate about the kind of organisms we might encounter if astrobiologists found life,” Ricciardi says. “The most plausible life forms are microbial and probably resemble bacteria. But unfortunately we don’t know if they can survive on Earth or what effects they might have.”

terrestrial microbes

The organisms that may have been or are being transported from Earth to other celestial bodies are most likely certain strains of bacteria and fungus, according to the researcher. “Probably the ones that can survive extreme dehydration and ionizing radiation,” he continues. “But again, we can only speculate about their potential impact without actually knowing about alien communities and whether they exist at all on the planets and moons targeted by upcoming space missions.”

Natural Disasters

All in all, Ricciardi wants to draw more attention to this subject with his study. According to him, we should even treat the threat of biological contamination between the Earth and other celestial bodies in the same way as impending natural disasters. “The risks of disasters such as massive earthquakes are usually extremely low,” he explains. “But for this to happen, while highly unlikely, is unacceptable. That is why we have taken preventive measures. The same goes for biological contamination. While the likelihood of a living alien organism being successfully transported to Earth and gaining a foothold is considered quite slim, such an event should be considered unacceptable. And so this requires strict protocols to prevent this at all costs.”

Prevention

Fortunately, this threat has long been in the crosshairs of space agencies. “NASA and ESA have long been aware of the potential risks of biological contamination,” Ricciardi said. “A policy for planetary protection has already been written. However, there are unprecedented risks associated with a new era of space exploration, targeting areas most likely to harbor life.” And so, according to the researcher, it is even more important that we are aware of the dangers and do everything we can to prevent biological contamination.

A logical follow-up question is, of course, how we should do that. “Early detection and rapid response are the keys to biosecurity,” said Ricciardi. “This is crucial for effective prevention, but can be undermined by inadequate identification methods. New DNA sequencing technologies coupled with well-curated databases on the organisms found in clean rooms can contribute to the earliest possible detection. Finally, given the obvious parallels between this problem and biological invasions on Earth, we argue for better collaboration between astrobiologists and invasion biologists to improve biosecurity on Earth, as well as on other planets.”