Exploring Mars is as important as going back… Can we find traces of life in the ‘dark microbiome’?

Research results have been published that DNA can provide an answer to the question of whether life lived on Mars. If NASA’s Mars rover, ‘Persistence’, which arrived on Mars in February 2021, can safely bring samples from Mars back to Earth, traces of life on Mars will also be visible through DNA analysis.

A research team led by Armando Assua-Bustos, a researcher at the Spanish Institute of Astrobiology, told the international journal ‘Nature Communications’, “If you want to find the ‘dark microbiome’, which traces life on Mars , it is impossible with Perseverance field probes, Mars samples should be returned to Earth for analysis,” he said on the 22nd. The dark microbiome is an unknown piece of DNA, a concept first proposed by Spanish researchers in this study.

The Spanish research team uses the ‘SHERLOC’ Mars Specimen Analysis Instrument (SAM), which was used in the exploration of Martian life in the Atacama Desert in Chile, and the ‘Mars Organic Molecular Analyzer (MOMA)’, which is used. for the Rosalind Franklin rover which is due to be launched in 2028. I made sure I could analyze the biome. The Atacama Desert is one of the driest regions on Earth, with annual precipitation of 1 to 3 millimeters. It is a place where performance tests of Mars life probes have been carried out as the environment has little humidity and dust blowing similar to Mars.

The delta region of the Atacama Desert experienced by the Spanish researchers is an example of Mars where sediments accumulate between 160 and 100 million years ago, and persistence is active. It has craters and similar geological features. When samples taken from the area were taken to the laboratory for detailed analysis, DNA from live and unknown microorganisms was found. In particular, 8.9% of the total microbial DNA was completely unknown, and approximately 40% could not be classified as a species. This means that almost half of the DNA detected comes from new extinct or as yet unknown microorganisms.

Spanish researchers have named these micro-organisms, which exist only as unknown DNA, the ‘dark microbiome’. It means that it is a micro-organism in an unknown region, like dark matter, which accounts for 23% of the constituent matter of the universe, but whose identity is unknown. DNA is the most structurally stable organic molecules, so it is preserved for a relatively long time, and unlike other organic substances, it is known not to be made outside of life, and this the strongest evidence for the search for life on Mars. , the researchers argued.

However, field probes could not detect the dark microbiome. The DNA of microorganisms that have already disappeared 100 million years ago is contaminated or decayed by the external environment, making it difficult to differentiate with general analytical tools. The research team analyzed that the DNA from billions of years ago, when life is expected to be able to live on Mars, would be similar to the Atacama Desert. They found that not only DNA, but also fatty acids and organic substances that can be produced by biological activities are too inaccurate to be analyzed with field inspection equipment.

Researcher Bustos said, “If there was life on Mars, it would have existed billions of years ago. A mission to bring samples back to Earth and examine them will definitely be necessary.”

Plans are underway to bring samples back to Earth for analysis rather than analyzing them directly from Mars. Perseverance has taken 38 tubes capable of holding Mars samples and bringing them to Mars, filling 18 tubes so far. In the future, the remaining tubes will be filled and transported to Earth by 2033 using the Earth Return Orbiter (ERO), which the European Space Agency (ESA) will launch in 2027.