Research funded by the European Research Council reveals that the Chilean Desert could hold clues about life on Mars. Scientists have found diverse microbes in layers of clay-rich, shallow soil in the Atacama Desert in Chile. Because this dry environment bears a striking resemblance to Mars, scientists believe microorganisms may exist below Mars’ surface as well. Future rover missions or landing crafts could easily detect any sign of life below the dry surface.
The research published November 5 in Nature Scientific Reports offers an example of identifying microbes potentially found in clay on Mars. Led by Cornell and Spain’s Centro de Astrobiología, this research could help guide future rover missions’ efforts.
The discovery in Chile
In the Chilean Desert’s arid environment, the researchers discovered layers of wet clay about 12 inches beneath the surface. They believe this could offer a glimpse into life on Mars as well.
“The clays are inhabited by microorganisms,” said co-author Alberto G. Fairén, a visiting scientist in the Department of Astronomy. “Our discovery suggests that something similar may have occurred billions of years ago – or it still may be occurring – on Mars.”
If microbes ever existed on Mars previously, scientists would likely find their biomarkers preserved there, Fairén said. “If microbes still exist today,” he said, “the latest possible Martian life still may be resting there.”
Mars will have rovers sent to its surface shortly to search for any signs of life. In February 2021, NASA’s rover Perseverance will land, and Europe’s Rosalind Franklin rover will arrive in 2023. Both of these missions have the aim of detecting microbial biomarkers in the clay below the surface.
“This paper helps guide the search,” Fairén said, “to inform where we should look and which instruments to use on a search for life.”
In the Chilean Desert, the microbial life beneath the soil had been previously unreported. However, in the Yungay region of the desert, scientists found that at least 30 microbial species inhabit the clay layer. The species include metabolically active bacteria and archaea (single-cell organisms), which survive in the salt-rich soil. Scientists believe this discovery supports the idea that Mars could have had a similar environment, especially in its first billion years.
“That’s why clays are important,” Fairén said. “They preserve organic compounds and biomarkers extremely well, and they are abundant on Mars.”
A previous study finds more evidence of possible life on Mars.
Last year, findings published in Frontiers in Microbiology revealed that subsurface soil samples contained unusual microbes. A robotic rover deployed in the Atacama Desert in Chile collected these soil samples during a trial mission. Their goal was to detect signs of life. Researchers found highly specialized microbes spread out in patches in the soil, which they believe occurred for several reasons. According to the researchers, the scarce water and nutrients, along with the chemistry of the soil, contribute to the distribution pattern of the microbes.
These findings will also help in the quest for detecting signs of life on Mars in the future.
“We have shown that a robotic rover can recover subsurface soil in the most Mars-like desert on Earth,” says research lead Stephen Pointing, a Professor at Yale-NUS College, Singapore. “This is important because most scientists agree that any life on Mars would have to occur below the surface to escape the harsh surface conditions where high radiation, low temperature, and lack of water make life unlikely.”
He says that the microbes they found have adapted to high salt levels. Those results are similar to what they’d expect in Mars’ soil. The microbes discovered in the Chilean Desert differ greatly from those found previously in desert environments. In the upcoming rover missions to Mars, they will drill below the surface for the first time to look for life signs. Scientists test the technology in Chile to ensure the success of these future missions.
“The core of the Atacama Desert in Chile is arid, experiencing decades without rainfall. It has high surface UV radiation exposure and is comprised of very salty soil. It’s the closest match we have on Earth to Mars, which makes it good for testing simulated missions to this planet,” argues Pointing.
Microbes found in patches in the desert.
An autonomous robotic drill and sampling device designed by Carnegie-Mellon’s Robotics Institute recovered samples 80cm into the soil. The sediment samples came from the Atacama Desert; researchers compared them to some they had recovered by hand. Using DNA sequencing, they discovered similarities in both samples, indicating a successful mission. However, the samples showed that the microbes had a patchy distribution, showing the difficulty of survival in the harsh environment.
“These results confirm a basic ecological rule that microbial life is patchy in Earth’s most extreme habitats, which hints that past or present life on other planets may also exhibit patchiness,” explain study co-authors Nathalie Cabrol and Kim Warren-Rhodes of The SETI Institute. “While this will make detection more challenging, our findings provide possible signposts to guide the exploration for life on Mars, demonstrating that it is possible to detect life with smart robotic search and sampling strategies.”
Pointing says that in the future, they will drill even deeper. This depth will permit them to observe how far below the surface the microbes can survive.
“Mars missions hope to drill to approximately 2m and so having an Earth-based comparison will help identify potential problems and the interpretation of results once rovers are deployed there. Ecological studies that help us predict the habitable areas for microbial communities in Earth’s most extreme environments will also be critical to finding life on other planets.”
In the next few years, the missions to Mars will hopefully prove successful and help us find evidence of past or present life. Advancing technology greatly aids in this endeavor. Thus, we will likely see huge discoveries made about life on other planets.