Are we alone in the universe? They hope that missions to Mars, and beyond, will say so this century

Madrid – After more than a year of studies on strange rocks discovered by the Perseverance rover on Mars, in 2024, scientists announced the discovery of the clearest evidence yet of signs of possible ancient life in Mars.

It remains to be confirmed, but for that to happen they must be examined on Earth, which would not happen before the year 2040.

While the United States government decides how and when to bring them, Other missions such as the European Rosalind Franklin and the Chinese Tianwen-3 are preparing to travel to Mars in 2028 and continue this scientific career.

“The next generation of scientists will have the exciting opportunity to investigate whether there was life on Mars,” Jesús Martínez Frías, a planetary geologist and astrobiologist at the CSIC at the Institute of Geosciences (IGEO) in Spain, tells EFE.

He added that “these explorations will help us understand how life originated on Earth, something still unresolved.”

Humanity has been sending probes for decades to search for life beyond Earth because “knowing whether or not we are alone in the cosmos is probably one of the most enigmatic and interesting questions for humanity,” he believes.

On Earth, known life forms are primarily composed of six elements: carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. He said that, therefore, these are the basic elements that we look for outside our planet, indicating that they are “signs or clues that allow us to go further and investigate their possible relationship with life.”

But to establish this connection, it is considered necessary that the place has or has had “habitable conditions”, elements capable of sustaining that life, says the president of the Spanish Network of Planetology and Astrobiology.

Mars meets the requirement: for several hundred million years, like Earth, it had water, atmosphere and environmental conditions very similar to those that made terrestrial life possible.

For this reason, Perseverance collected rocks in Neretva Vallis, a channel located at the entrance to the Jezero crater, where 3.8 billion years ago a river flowed and deposited sediments in a lake. The place had been carefully selected to collect the samples that “are like pieces of a puzzle that help us understand how the evolution of the planet has been,” says Martínez Frías.

After a year of multidisciplinary analysis, an international team of scientists announced that they had found “a possible biosignature”, that is, “probable signs of the action of microorganisms that were captured in the rocks in the form of traces of their activity,” explains Martínez Frías, who is also co-author of the study published in Nature.

The samples contained small mineral nodules, with chemical reaction fronts, enriched with iron sulfide and iron phosphate – on Earth they are associated with the decomposition of organic matter – that could have been originated by authigenic processes (inside the old clay sediment) with the participation of microorganisms capable of using iron or sulfate as occurs in some places on Earth.

But this mixture of minerals could have been formed in chemical processes without the intervention of living beings, that is, in an “abiotic” way, he warns.

So why are they special? Because they contain an association of minerals, very peculiar textures and organic carbon, “a combination of unique and unprecedented characteristics completely different from the rocks collected by Curiosity, Opportunity or Spirit, and different from Martian meteorites and, all of this, within a context of habitability on the ancient watery Mars,” summarizes the scientist.

“They are, without a doubt, the clearest possible biosignature found so far,” emphasizes Martínez Frías.

To determine if they really are “biosignatures,” the samples must be analyzed on Earth but The mission of NASA and the European Space Agency that was to bring them has been on hold since the arrival of donald trump to the American government.

The Rosalind Franklin rover (equipped with a 2-meter drill) or the Chinese Tianwen-3 probe, which will bring the samples to Earth in 2031, could corroborate this sooner.

Until now, the rock considered as possible evidence of past life on Mars was the meteorite ALH 84001, discovered in 1984 in Allan Hills, Antarctica, but “today it is almost ruled out” and it is believed that these signs were generated abiotically, explains Martínez Frías.

Before Perseverance, other missions suggested that there could be microbial life on Mars: in 1976, the Viking probe found a chemical reaction that was at the time attributed to microorganisms and, in 2018, Curiosity found organic compounds preserved in shales (sedimentary rocks) that, however, could have reached the planet in a meteorite (it is estimated that between 70 and 100 fall every day tons on Earth and Mars).

“These meteorites called carbonaceous chondrites are rich in organic compounds and have amino acids, sugars, among others, and can even contain nitrogenous bases, which are the fundamental building blocks of DNA” but in reality they are not even Martian, he points out to EFE.

Mars is not the only candidate. There are other worlds where there could be life and to search for it, missions have already been planned for the moons of Jupiter (Europe), and Saturn (Enceladus and Titan), and the planet Venus.

“The most interesting are the icy moons Europa and Enceladus. Both have a habitable environment, liquid water, energy and are a geologically living body where it is more plausible that life could have emerged,” says Frías.

To study Europa’s salty ocean, NASA will send the Clipper mission in 2030, which will fly over the moon about fifty times, and by 2040, the European Space Agency is preparing a mission to study the spectacular geysers that emanate into space from the ocean of Enceladus, where an abundance of phosphorus, an essential nutrient for life, has been detected.

Also in the 2030s, NASA’s Dragonfly spacecraft will arrive at Titan to study its atmosphere, rich in organic compounds and with “very unusual” conditions that will allow the study of prebiotic chemistry.

“Investigating these places is exciting,” and “if life has emerged on another planet or moon in our solar system, I am convinced that we will be able to detect it in this century,” concludes the astrobiologist.