The new paper highlights the fact that we may find living microbial life in red planet samples, as it may have been lying dormant under the surface for eons. This is because bacteria could survive just under Mars’ surface for much longer than previously thought.

Dormant life on Mars

The new findings prove that certain strains of bacteria can survive even in Mars’ harsh environment, drawing up the possibility that future crewed missions could contaminate the red planet and bring Martian bacteria back to Earth.

Crucially, the discovery also means that future Mars drilling missions, including ExoMars and the Mars Life Explorer, are more likely to find bacterial life two meters below the red planet’s surface than previously thought.

“Our model organisms serve as proxies for both forward contamination of Mars, as well as backward contamination of Earth, both of which should be avoided,” Michael Daly, a professor of pathology at Uniformed Services University of the Health Sciences (USU) and member of the National Academies’ Committee on Planetary Protection, who led the study, explained in a press statement.

The study proves that microbial life could be found today only a short distance below Mars’ surface. Still, its authors also caution that bacteria from Earth could hitch a ride aboard a future Mars mission, causing irreversible problems in the pursuit of scientific knowledge.

“We concluded that terrestrial contamination on Mars would essentially be permanent — over timeframes of thousands of years,” said Hoffman, a senior co-author of the study. “This could complicate scientific efforts to look for Martian life. Likewise, if microbes evolved on Mars, they could be capable of surviving until present day. That means returning Mars samples could contaminate Earth.”