Finding life on Mars may be harder than we thought. this is the reason

(CNN) – New research has revealed that finding possible signs of life on Mars may be more difficult than expected.

Missions such as Perseverance and Curiosity rovers are equipped with an array of scientific instruments that can analyze rock and dust samples and gather data about the Red Planet. However, these instruments, as well as those designed for future missions, may not be sensitive enough to detect biosignals, that is, signs of current or ancient life.

To test the capabilities of these scientific tools, the researchers went to the Chilean Atacama Desert, which is the driest place on earth and the oldest desert in the world. Scientists have long considered this barren desert an analogue of Mars, especially when researchers stumbled across the Jurassic fossil delta of Piedra Roja. The river bed, which is 100 million years old, resembles the Jezero crater and its ancient river delta on Mars.

The Perseverance rover is currently exploring the crater and delta, where there was a lake and river more than 3 billion years ago, to search for signs of ancient life and collect samples. Soil and rock collected by Perseverance will be returned to Earth in the 2030s by NASA and the European Space Agency’s Mars Sample Return campaign.

A team of researchers explored the Pedra Roja site in northern Chile to see how it compares to the Jezero crater and found that they are geologically similar, composed of sandstone and clay, as well as hematite, the same iron oxide that gives Mars its distinctive red color. .

Mars-like conditions on Earth

The researchers collected riverbed samples and analyzed them using highly sensitive laboratory equipment. Pushed to the limits of their detection capabilities, the lab team’s analyzes revealed a mix of biosignatures from both extinct and living microorganisms. Although the redstone is incredibly dry, it is close to the ocean, where the haze provides water for microbial life.

Many of the microbes’ DNA sequences came from an unknown “dark microbiome,” a nickname for the genetic material of hitherto unknown microorganisms. The researchers coined the term because it is similar to dark matter, a hypothetical form of matter in the universe that remains unidentified.

The researchers went further and tested four scientific instruments designed to explore the Red Planet in samples they collected from an ancient river bed. Despite being very complex, the tools were barely able to detect any molecular signatures, which indicates that the tools may not be sensitive enough to accurately detect biosignals.

The study was published Tuesday in the academic journal Nature Communications.

Detecting life will require advanced tools

Missions to Mars have been searching for signs of life on the Red Planet since the first Viking lander arrived on the planet in the 1970s. The most advanced instruments on subsequent NASA missions have detected simple organic molecules, but they can arise from chemical reactions unrelated to life.

If life existed on Mars billions of years ago, only low levels of organic matter are expected to remain, meaning that identifying signs of past life on Mars would be very difficult with current technology, according to the study.

“The possibility of false negatives in the search for life on Mars highlights the need for more powerful tools,” says the study’s lead author, Dr. Armando Azua-Bustos, a research scientist at the Center for Astrobiology in Madrid.

The study results support the goals of the Mars Sample Return Program, a multi-mission effort that will return Martian rocks and soil to Earth, where scientists can analyze them using state-of-the-art laboratory equipment to search for clear, unmistakable signs of life.

“Our results underscore the importance of returning samples to Earth to definitively determine whether life existed on Mars,” the researchers wrote in the study.

Care should be taken when evaluating the first Mars samples returned to Earth, Carol Stocker, a planetary scientist at NASA Ames Research Center in Mountain View, California, wrote in a paper. Opinion article accompanying the study. Stocker was not involved in the investigation.

“It is assumed that any biological activity in these samples occurred billions of years ago, and only a few small samples can be returned to Earth for study,” Stocker wrote. “It remains to be seen whether unmistakable fingerprints of life can be found in these limited specimens. We must be careful about interpreting the absence of strong evidence of life as evidence of its absence!”

One of the tested instruments will travel to Mars aboard Europe’s first rover, the Rosalind Franklin, which is scheduled to launch on the Red Planet in 2028.

Ferrin, a study co-author, research scientist at the Center for Astrobiology in Madrid and visiting scientist in Cornell University’s Department of Astronomy.

“If biosignals are better preserved at depth, as we expect, then there will be more abundance and diversity, and better preservation of biosignals, in those deep samples. Our instruments on the rover will therefore have a better chance of detecting them.”