How did you make the University of Nantes a stronghold for the study of the planets of the Solar System, with the Planetology and Geosciences Laboratory (LPG)?
When I started at the University of Orsay, in 1988, we realized that missions in preparation to Mars and the ice satellites of Jupiter and Saturn needed the skills of specialists in Earth sciences, who study surfaces and interiors. No lab of this type really existed in France and a colleague told me that it was possible to create one in Nantes, where I am from. From 1993, LPG developed, and there are now 70 of us working on it. It has become an international reference.
You were also appointed scientific director in one of the most prestigious laboratories in the world, NASA’s Jet Propulsion Laboratory (JPL), to which we owe legendary space missions like the two Voyagers. How was a Frenchman able to access this position?
I had the opportunity to work on the Cassini-Huygens mission (launched in 1997 to explore Saturn and its satellites) and to calibrate its infrared camera at JPL in the early 1990s. Then, in 2005, its management issued wanted to hire me because she was looking to strengthen her skills in the geology of ice satellites. But I had to refuse, a little with sadness in my soul, for personal and professional reasons. After being invited for two years to teach there regularly, my family and I finally broke down and moved to California. Then, I was asked to take scientific direction for the exploration of the Solar System. I never thought I would get this type of position at JPL! I accepted and completed two four-year mandates, the last of which ended in 2020.
What is JPL’s recipe for excellence, which is capable of achieving feats like landing rolling robots on Mars?
JPL is responsible for NASA’s so-called “flagship” missions, those with the largest budgets, since the end of the 1970s. It is above all an engineering laboratory, whose know-how is recognized worldwide: 6,000 people work there, two thirds of whom are in engineering, with a very advanced technological research section, particularly in the miniaturization of instruments which also finds applications in medicine and in everyday life.
You participated in the development of the Europa Clipper mission, launched on October 14, towards Europa, one of Jupiter’s moons. What was your work on this project with a budget of five billion dollars?
We met politicians, members of Congress who vote on NASA budgets, to explain to them why exploring Europe had become a priority, from a scientific point of view. Looking for funding was one of my main occupations. For Europa Clipper, we managed to obtain significant research and development budgets which made it possible to develop new techniques, both to protect against Jupiter’s radiation and to carry out new spectroscopic analyzes of the surface of Europa.
Why is sending space probes to study the moons of Jupiter like Europa, but also Ganymede, with the European Juice mission (launched in April 2023) so important? Will they make it possible to detect life there?
With these two missions, we will not have the answer regarding the existence of life on these satellites. Their goal is to better understand the ocean that is present in each of them, under the ice layer. By observing their surface, we will also be able to see if a sample of this ocean could have been expelled by processes of ice volcanism. On Europa, we have conditions similar to those that exist at the bottom of the Earth’s oceans. Knowing whether life was able to develop there would help answer the question of the emergence of life on Earth.
Will we one day be able to drill their ice surface to reach these oceans which may be home to forms of life?
At JPL, I worked on mission concepts. One of them was to send a lander to Europa, to obtain more information about its surface and to work on drilling down to the ocean. But how deep? We don’t know. We need Europa Clipper and Juice for that. The thickness of ice, which exists above the ocean, may very well be a few hundred meters or several tens of kilometers.
What does your Promises program consist of, carried out in Nantes since 2022 and endowed with 2.3 million euros from the European Research Council?
The question posed is to know where the building blocks of life come from. Life is in fact made up of certain organic molecules. We are trying to see if they exist among the organic molecules synthesized, before and during the formation of the Solar System. To do this, we work on data from the Rosetta and Dawn missions (which studied a comet and asteroids, vestiges of the formation of the planets of the Solar System four billion years ago) and carry out laboratory experiments and simulations digital.
The search for life is also carried out outside the Solar System, on extrasolar planets. Is this a promising avenue?
The detection of extrasolar planets (the first in 1995) was a boom. Many have been discovered, there are now almost 6,000 confirmed. Scientists are working on biosignatures, characterizing the atmosphere of these exoplanets, notably with the James Webb Telescope. However, the detection of life will be extremely complicated due to the significant distances that separate us from them, even if we continue to make progress in improving observations.
The current era is experiencing a resurgence of discourse, sometimes conspiratorial, which calls into question certain scientific consensus, on social networks or on television sets. How to protect yourself from it?
With the development of social networks, everyone can express themselves, including extremes, to the point of saying that the Earth is flat… This is why education and teaching are essential. Thanks to them, we are able to integrate the results of research carried out over the last 50 years. Space missions have, for example, brought a huge amount of knowledge. Before the 1960s, science fiction films talked about possible life on Venus, this is no longer the case today…
In many political speeches, the time seems to be for withdrawal. Can scientific research afford it?
In terms of scientific research, we are extremely open, the data acquired is made available to everyone. At the LPG in Nantes, we welcome around twenty students from all over the world via a master’s degree financed by the European Union. And regarding space missions, which are expensive, there is a need for international coordination in order to be complementary. This is the case with Europa Clipper and Juice.
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