Mars: Proving life is more difficult than thought

Updated 2/21/2023 5:06 PM

• Various missions are looking for signs of life on Mars.
• A study now shows that the tools used are insufficient.
• The researchers recommend a more reliable method.

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Was there life on Mars – and perhaps simple forms of life have survived on the Red Planet to this day? Answering these questions is an important goal of many current and planned spacecraft. However, as experiments by an international research team are now showing, the tools developed for this purpose may not be able to detect past and present traces of life on Mars. So only examining soil samples in a ground laboratory can answer these questions, The scientists write in the journal Nature Communications..

Researchers led by Armando Azua-Bustos of the Center for Astrobiology in Madrid examined soil samples from the redstone region of Chile’s Atacama Desert using the best methods possible in a ground-based laboratory, as well as instruments like those used by current or planned spacecraft. user. A river delta in the extremely arid Atacama Desert that dried up more than 100 million years ago, the Redstone is thought to be the region on Earth that most closely resembles conditions on Mars today.

Also read: NASA fascinates with the new image of Mars

Using modern techniques such as DNA sequencing, Azua-Bustos and colleagues easily detected active microbial life in soil samples from the Atacama Desert. In some cases it has been possible to grow microbes from samples. The majority of detected microbes are of previously unknown forms. The researchers also found a large number of biosignatures – organic molecules that are typically components of microbes – from past life forms.

Instruments on Mars are working poorly

The team then analyzed the soil samples themselves with instruments such as those on board Curiosity’s Mars rover or for the European ExoMars rover. Although the analog “Curiosity” device had ten times the sensitivity of the original device, it was still only able to detect a few vital signs within its detection limit. According to the researchers, the original tool would have failed here. MOLA, the Mars Organic Molecular Analyzer instrument planned for ExoMars, didn’t fare much better: It only detected some organics in the samples.

It is therefore expected that current or currently planned missions will not find a definitive answer to the question of life on Mars, according to scientists. Azua-Bustos and colleagues confirm. Only then can samples be thoroughly examined for signs of life in laboratories on Earth.

In fact, the US rover Perseverance has been collecting rock samples on its return mission to Earth since 2021. However, it is currently quite open when and by what means such a mission could actually take place.

In an accompanying commentary in Nature Communications, planetary scientist Carol Stocker of NASA’s Ames Research Center also notes that such missions can only bring a small amount of rock back to Earth. “It remains to be seen whether clear signatures of life can be found in these limited samples,” says the researcher. “So we have to be careful about taking the absence of clear evidence as evidence of the absence of life.” (dpa/cze)