Nathalie Cabrol: “To think that we are alone in the Universe is a statistical aberration”

Nathalie Cabrol To think that we are alone in the

“You have to be attentive to intersections. Not necessarily road intersections, but those of existence.” Nathalie Cabrol has the short hair of a Joan Baez and the outspokenness of a Patti Smith. These American rock & folk references would not displease her, she who has spent most of her career in the United States. Let’s say it straight away, this astrobiologist who has just published At the dawn of new horizons (Seuil), appears like a UFO in the French scientific landscape, as much as the extraterrestrial signals that it tracks down by directing the prestigious Carl-Sagan research center of the Search Institute for extra-terrestrial intelligence (Seti).

A vocation born watching Neil Armstrong set foot on the Moon

The researcher has something mystical pegged to the body since her earliest childhood: “I have always been fascinated by the firmament, its immensity and its stars that I observed at 5 years old in Provence.” At this age when toddlers go to bed early, she gets up at 3 a.m. on July 21, 1969 when, as part of the Apollo 11 mission, Neil Armstrong was the first to set foot on the Moon. “I was with my mother, snuggled up on the sofa and I remember the endless wait before the door to LEM opened. [NDLR : le module d’atterrissage lunaire] for him to descend the steps of the ladder one by one. I was hypnotized by these ghostly black and white images. That day, I told mom that I wanted to become an astronaut.” It’s hard to find a better definition of the word “vocation”. The little girl does not budge and draws dozens of spaceships, “more star trek that Star Wars“because they went in the sky but also under water, another of his fads. With, in the background, always an identical landscape made up of domes and hills. “The same finally as the one I have discovered twenty years later by entering the Observatory of Meudon where, on the wall, were detailed photos of the moons of Saturn.

She is like this, Nathalie Cabrol, renowned scientist, to see premonitions everywhere. As a teenager and still sure of her dreams, she even sent letters to the National Center for Space Studies (Cnes) as well as to Commander Cousteau. Astronaut Patrick Baudry takes the time to answer him to encourage him while pointing out that a lot of work still needs to be done. Which does not scare her since she begins brilliant studies until… hypokhâgne. A small detail, it shines more in literary subjects than in science: farewell to engineering schools or other maths sup/maths special preparations. Farewell also to the path mapped out towards the career of astronaut. In France more than elsewhere, his passion for the stars should have stopped there. But while the doors are closing one after the other – “which finally makes it possible to trace a path” -, she follows the lessons of a professor of geography, Jean-Pierre Allix, passionate about the planets, their physics, their geology and their environment. Head to Nanterre for an Earth science course. First intersection of life, first bifurcation far from the illuminated universe of classical letters.

During her college years, she worked in a laboratory specializing in natural hazards. “I was in my element, I even put on my first mountaineering crampons [NDLR : activité qu’elle pratique toujours]. But I always had my head in the stars, I read everything that came out in astronomy.” And there is a moment when it ends up showing: another of his professors spurred him on in the direction of the Meudon Observatory to make her meet one of her colleagues, André Cailleux, a geographer but also a planetary scientist who gives her a long interview that turns out to be a job interview, his eyes riveted on pictures of the planet Mars freshly transmitted by the Viking probe. decisive crossroads: the young woman put down her suitcases at the Observatory and was enthusiastic about the Martian terrains of which she was to become one of the greatest specialists. We are in 1985, and no one yet knows (especially not her) that Nathalie Cabrol will be behind the landing choice of the first American Spirit rover in 2003.

Head to the United States

Before getting there, the Frenchman is working on her thesis devoted to the paleo-channels of the extinct little sister of the Earth. The Observatory is an ideal place, visited by the greatest astronomers. She also meets there the hydrogeologist Edmond Grin, who will become her companion, but also Christopher McKay, one of the managers of the Mars exploration rovers (MER) program of the American Space Agency (Nasa). “One morning, I find him particularly concerned and he tells me that NASA has the technology to go so far but that in the end, it doesn’t know where. I offered to come up to my office to tell him about my work on the Martian lakes and more particularly on the Gusev crater. And a few weeks later, I left with him for the United States where I have now worked for almost twenty years! Third decisive intersection.

In California, at NASA’s Ames research center, even for this specialist in ancient hydrography, life was not a long calm river. Integrated into the MER program, it multiplies the scientific articles to target the best landing places in order to better study the past habitability of the Red Planet. In 1998, his research allowance ran out. To continue working with the American agency, he must find a paid position. She then passed through the doors of the Carl Sagan Center, the research division of the Seti Institute where Christopher Chyba offered to receive her. But that day, the latter is on the move. “I was received but at the other end of the table was Frank Drake and my heart raced.”

Drake, in fact, is a legend of modern astronomy (founder of Seti), known in particular since 1961 for the eponymous equation which aims to deduce the number of potentially active and detectable extraterrestrial civilizations in our galaxy. “He received me with incredible kindness, taking an interest in my background and my work. We stayed one-on-one for forty-five minutes and it was he who recruited me as a researcher.” New meeting, new turning point which settles it definitively in Mountain View on the west coast of America. There, she continues her work but somewhat abandons her high-resolution Martian photos for other heights, those of the Andes. “The Seti is tracking possible traces of extraterrestrial life that may have developed in extreme conditions: I then proposed to look for these extreme conditions but on Earth, namely arid places, with high UV levels, a strong pressure, therefore at altitude. And it is in the Atacama desert, then between Bolivia and Chile that we have set up annual expeditions.” In this volcanic and hydrothermal environment, the objective remains to understand how certain organisms can survive and how (with what type of instruments) to detect them. This project called Grands Lacs continued without interruption (or almost) until 2019. “The first year, I remember finding a prehistoric arrowhead similar to the one I had seen the day before we left in the San Pedro Museum. I was moved by it because it recalled the human presence thousands of years before ours, as if it made the link between the past and the present. I am very attached to symbols.”

It was she who was behind the choice of the landing site for the Spirit rover in 2004

In parallel with her summer missions, Nathalie Cabrol continues in the more subdued atmosphere of Seti to weigh in on the Mars rovers program. “Initially, there were 152 sites selected for the landing of Spirit in 2004. A compromise had to be made between what we scientists found more interesting and what the engineers could do in order for the robot to reach its landing point. with maximum security. Under these conditions, the Gusev crater defended by the French turns out to be far from being the safest. But from meetings in workshops in Pasadena, she will persuade her colleagues up to the highest levels of NASA, since her director at the time ended up giving her reason with very Kennedy tremolos to justify her choice: “It’s a dangerous site but we’re going to do it because it’s more scientifically interesting.”

“I am one of those who think that life is not so far from the surface.”

Today, of the three American rovers sent to the surface of Mars, two are still operating. They showed the past habitability of the Red Planet but also that it still contains in places the conditions necessary for life. Currently, Perseverance is collecting samples that one of its successors will recover in 2033. Until then and until an astronaut sets foot on Martian soil, Nathalie Cabrol thinks that the rover epic is coming to the end of ‘a cycle. She is campaigning for a network of mini-stations “easily droppable from orbit” to take over in order to constantly monitor the Martian environment. “It would be a question of focusing on the polar regions using sensors the size of a can of Coca-Cola which would give live basic information (winds, temperatures, etc.).” With the hope of discovering an active life? “No, not in the form of little green men, but microbial: the Great Lakes missions have shown that organisms can develop and persist in extreme environments. On Mars, this could also be the case in these polar regions, despite the radiation cosmic.” And the Frenchwoman to assure: “I am one of those who think that life is not so far from the surface.”

The revolution in the discovery of exoplanets

And can not so far also mean elsewhere in the solar system? “In terms of prebiotic chemistry and to understand how life appeared, the best refrigerator remains Titan, the small satellite of Saturn.” Enceladus, his little sister, would also be a good candidate. But for the scientist, the preferred target is undeniably Europa, the moon of Jupiter whose immense liquid ocean can harbor complex life: “Some colleagues even think that it contains fish. I am not a specialist in this question but I’m not going to contradict them because I like that idea.”

Finally, the revolution unfolding before our eyes concerns the very distant, beyond our solar system. First in our galaxy where the first exoplanets – located in the habitability zone of their star – were discovered in 1995 and whose catalog of detections (5,300 to date) continues to swell thanks to the most advanced telescopes. advanced (Kepler, Jess and now the JWST). “We can reasonably think that in our galaxy alone, there are nearly 300 million,” insists the researcher. To put in resonance with another figure: there would be 125 billion galaxies. And Nathalie Cabrol concludes: “To think even today that we are alone in the Universe is a statistical aberration.”