Increasing demand for space exploration is also increasing the chances of extraterrestrial organisms invading Earth and organisms on Earth invading other planets, scientists argue in a new study.
The researchers point to mankind’s tendency throughout history to bring species to new environments on Earth, where those organisms can become invasive and destroy native species. Such behaviour suggests that something similar could happen with alien life from other planets contaminating Earth and vice versa, according to the study published in the journal BioScience.
“It is crucial to reduce the risks of biological contamination in both directions” said Anthony Ricciardi, lead author and professor at McGill University in Montreal.
Humans have destroyed ecosystems around the world
Ricciardi and his colleagues call for more collaboration between astrobiologists searching for alien life and biologists studying invasive species on Earth.
Scientists believe the risk of interplanetary contamination is extremely low, largely because all those harsh conditions of outer space make it difficult for organisms to survive on the outside of a human spacecraft. However, mankind should be cautious given the negative effects invasive species have had on Earth, according to Ricciardi.
Humans have destroyed ecosystems around the world by allowing organisms to invade new environments that they would never have reached naturally. For example, a fungus from South America called Austropuccinia psidii was introduced to Australia under unknown circumstances and attacks the country’s native eucalyptus trees, disrupting their growth and sometimes even causing their death.
A 2019 incident demonstrates the human potential for biological leakage
Researchers also pointed out that island ecosystems that evolve in geographic isolation, such as islands and countries like Australia, are extremely vulnerable to invasive species because native wildlife in those places has not adapted to deal with these invaders. “Biological invasions have often been devastating to plants and animals in these systems. We argue that planets and moons that might contain life should be treated as if they were island systems,” Ricciardi added.
The researchers also referred to the Israeli spacecraft Beresheet that crashed on the Moon in 2019 while carrying thousands of tardigrades, microscopic animals that can survive in extreme conditions, including the vacuum of space. A 2021 study concluded that the creatures most likely could not have survived the impact but the incident demonstrates the potential for biological contamination.
Planets and moons have always exchanged material via meteorites, but human space exploration could accelerate contamination, explained Jennifer Wadsworth, an astrobiologist at the Lucerne University of Applied Sciences and Arts in Switzerland.
