Curiosity and Perseverance, NASA’s two small rovers, have been exploring the Martian surface for years, but scientists from other countries believe their sensors may not be sensitive enough to find signs of life there.

The team compared copies of the rovers’ tools to modern lab equipment when testing them on sedimentary fossils discovered in Chile’s Atacama Desert. They found that the Martian instruments were unable to detect much, whereas the modern equipment discovered a variety of extinct and living microorganisms.

The results suggest that such low quantities of organic matter, predicted to be present if life existed on Mars billions of years ago, would be difficult, if not impossible, to detect with the technologies now in use on Mars.

A report published in Nature Communications argues that scientific tools presently in use on Mars may lack the sensitivity necessary to detect probable evidence of life in this environment.

There have been several initiatives to look for evidence of life on Mars since the Viking missions in the 1970s. Even the most modern, very advanced equipment on NASA’s Curiosity and Perseverance rovers have only been able to detect trace amounts of basic organic compounds fifty years later.

These findings raise the issue of whether the minerals in martian rocks or the limits of our present instruments are impeding our capacity to find signs of life.

Armando Azua-Bustos and colleagues used devices that are already or may be deployed to Mars, as well as cutting-edge laboratory equipment, to analyze samples from Red Stone, the sedimentary fossils of a river delta in Chile’s Atacama Desert.

These deposits resemble the Jezero crater on Mars, which Perseverance is now studying, in terms of their geology, and were developed under very dry circumstances between 160 and 100 million years ago.

The authors discovered a variety of biosignatures of both extinct and current microbes using extremely sensitive laboratory-based approaches.

Much of the DNA sequences discovered originated from an unidentified ‘dark microbiome,’ with the majority of the genetic material originating from previously undescribed microbes, according to microbial culture and gene sequencing.

Analysis of the testbed devices used on Mars, however, shows that they were only just able to identify molecular fossil signals near the limits of detection.

According to the results, such low quantities of organic matter that would have been present if there had been life on Mars billions of years ago would be challenging, if not impossible, to locate with the equipment in use there right now.

The authors emphasize the significance of bringing samples back to Earth in order to answer the question of whether life has ever existed on Mars.

Image Credit: Getty