Le mardi 9 décembre 2014, André Brahic était l’invité de la Société astronomique de Bourgogne. Le sujet de sa conférence intitulée Enfants du Soleil : À la recherche de nos origines et de la vie dans l’Univers portait aussi bien sur l’origine du Système solaire que sur l’exobiologie. © Jean-Baptiste Feldmann

Andrei Braic, the master of planetary rings, passed away 5 years ago

Andrei Braicz died of cancer five years ago. He was a Professor at the University of Paris-VII Denis Diderot and Director of the University “Gamma-Gravitation” at the Atomic Energy Commission (CEA Saclay), but above all he was a passionate and remarkable figure in the popularization of science. Known to the general public. He is also the recipient of the 2000 Carl-Sagan Prize in the United States and the 2006 Jean-Perrin Prize for this reason. For his colleagues, he was a co-discoverer of Neptune’s rings and an important figure in the Voyager and Cassini expeditions.

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[EN VIDÉO] Cassini’s wonderful voyage to the world of Saturn
On September 15, 2017, the Cassini probe will dive into Saturn’s atmosphere. He would have allowed great discoveries, leaving behind hundreds of thousands of “Lord of the Rings” portraits and revealing his moons in detail. Relive his unforgettable saga.

“What purpose is worth being born instead of not being?” To divine the sky and the arrangement of the entire universe “, Thus expressed by the Greek philosopher Anaxagoras in V.e Century BC This idea was hard not to share when listening Andrei Braich He spoke to us with communicative enthusiasm about the latest developments in planetary science Across Major space probe projects like Voyager, Cassini, and Science quite simply as shown in the video below. The intellect brews him with humor, and at times it can be lethalAstrophysicist World famous, in 1984 he participated in discovering episodes Neptune, And it’s been a regular show on TV since the 1980s where he’s occasionally found companyHubert Reeves and Jean-Pierre LuminetOther major extension workers.

Unfortunately, on May 15, 2016, A. cancer.

In 2011, he gave a long interview with Futura-Sciences, despite the fact that he was overwhelmed by his multiple activities, particularly as a member of the film crew for the Cassini expedition, which is currently exploring Saturn He is Monday. The researcher explained his background to us.

To mark the end of the Cassini mission on 09/15/17, André Braicz, the famous French astrophysicist and great engineer, is honored with the Saturn Exploration Expedition. Acknowledgment: Astronomical Festival. © CNES

From simulations of galaxies to images of planetary rings

Born on November 30, 1942 in Paris, he has quite started Jean-Pierre LuminetBy studying mathematics. In licensing, like many French astrophysicists who became famous, he is under the influence of courses (which he takes as an option) and enthusiasm.Evry Schatzman He has definitely turned into a worldAstrophysics. Gravity and the personality of who was the father of French astrophysics affected him deeply, but his encounter with the mathematician W. astronomer Michelle HenonHis thesis supervisor, who has played an integral role in his career.

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Henon is considered one of the best scholars of the late twentiethe century. His work on stellar dynamics and the problems of the N-body is considered authoritative. In imitationHenri Poincaré, And explora la physique The famous strange attractant chaos is discovered which Door its name. Andre Braic will praise him at a wonderful conference which can be found in the video ofHenri Poincaré Institute.

In the early 1970s, Andre Brake was studying collisions of an N-type system. Interstellar clouds In order to understandflattening From Spiral galaxies Disc formation. To test his model, he applied it to a training Saturn’s rings, A group of N objects orbiting the planet and subject to continuous mutual collisions. This star seemed to him at first, intuitively, not very interesting, compared to a scientist stars And the GalaxiesUntil he realized the biggest names in astronomy had broken their teeth there. GalileoCassini, Laplace, Maxwell and Poincaré, to name a few, have dedicated a part of their lives to her without being able to solve all the problems these episodes pose.

But an invention Computers That makes it possible Numerical simulation Complexes and launches of space probes that make it possible to closely observe the stars Solar system You changed everything. Saturn’s rings became real physical laboratories, close at hand, and it would take us a few more centuries to figure it all out.

Finally, while he thought he would only devote a few months to studying rings, Andre Braic spent more than thirty-five years there. And he did not regret that this decision will be his life’s chance. In fact, when preparatory work began for the Voyager missions, no one in the world was studying the evolution and dynamics of Saturn’s rings. It was natural that the French researcher was then offered to join Voyager’s imaging team to analyze the data on the rings.

The adventure of the Voyager probes and the discovery of the rings of Neptune

Responders Voyager I am And the Voyager II Built in Jet Propulsion Laboratory In Pasadena, California. The Jet Propulsion Laboratory is based on the well-known California Institute of Technology or Richard Feynman He was one of the teachers. At the beginning of the 1960s, at the conclusion of one of his famous physics courses on hydrodynamics, he was the great theorist Elementary Particles He predicted that when the exploration of the solar system was more advanced, it would be a useful lesson in physics. We shall then see a great wealth of phenomena, largely unpredictable at the present stage of evolutionIntelligence Human, will come out of simplicity Equations Like the laws of mechanics and gravity from Newton, And in particular that of Navier-Stokes fluid mechanics.

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This richness and diversity, which never ceases to surprise researchers, is very present in the solar system, such as André Braik’s work published by Odile Jacob titled Of fire, ice and fiery planets. The author relates the following anecdote, among many others: As part of the Voyager Probe photography team, in the 1980s, we had fun before each encounter by predicting the stars’ profiles just before their visit. Whoever loses the bets we make, he will invite his peers to the best restaurant around. Upon arrival, everyone called everyone! From astronomers, we have become gourmets! ».

Richard Feynman, André Brahic only caught sight of him a few times, but in the early 1980s another star was well present on the JPL Voyager Probe filming team: Carl Sagan. They would become very close friends and this is how one of the men behind the show did he sat And you The golden record De Voyager will hold an audience conference with André Brahic in Toulouse. As captivated to Futura-Sciences, André Brahic felt in total agreement with an approach Carl Sagan, For his sake, as he did with his hit series CosmosIt is important to share the scientific culture with as many people as possible, the scientific and rational spirit upon which it was founded, and the questioning of the landscape of the laws of nature operating in astrophysics.

In 1995, on the Cassiopée program, André Brahic and his collaborator Cecil Ferrari told us about the discovery of planetary rings in the solar system. © Jean-Pierre Luminet

From the rings of Saturn to the rings of Neptune

In 1989, the probe Voyager 2 Filming of Neptune’s rings demonstrated for the first time in 1984 will be permitted thanks to theHide Stars proposed by Andre Braic and colleagues, Bruno Sicardi and Françoise Rock of the Paris Mudon Observatory, and produced by Patrice Bouchet, Reynolds Hafner and Jean Manfred at the La Silla Observatory (Which – which). Also confirmed by the observations of F. Vilas and L.-R. Elicer, after a program led by Williams Hubbard. The five rings of Neptune are named after the astronomers who have contributed to important work on this planet: Galle, Lee Verrier, La Ciel, Arago and Adams. Also in 1989, we discovered with Voyager three arches in the final episode (Adams) that were baptized Equal freedom And the the brothers. Cecil Ferrari actually discovered that there was a fourth arc that has since been named BraveryThe letter “c” is said to refer to the French astronomer.

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In June 1980, when the Voyager 1 probe was about to reach the outskirts of Saturn and faced the success that Voyager had already made in exploring Jupiter, Andre Braic and some of his colleagues were already thinking about the next step, that is to say, putting a probe around Saturn in orbit. Bridges From Voyager 1 and 2. Not all of them are enthusiastic, however, because the project is too ambitious and too expensive.

So, Andrei Braich switched his teammates a little cautious, telling them: “ In life it suffices to say that one thing is impossible to become It would take ten years to NASA The European Space Agency and the European Space Agency have agreed to build the Cassini probe, which will be launched in 1997. The mission itself will cost about $ 4 billion, which is roughly the same as Construction The LHC It would eventually be extended at least until 2017, when Andre Braic was still intending to work on the film crew for the Cassini expedition, due to sensitivity to the idea of ​​retirement. Moreover, he would see himself, still alive, as a member of a mission specifically dedicated to studying Neptune and its rings by 2060.

When asked about the possibility of discovering extraterrestrial life in the near future, the great passion of Karl Sagan, Andrei Braich was very cautious, but likely confident. ” When asked whether extraterrestrial life exists, the world can only answer: I don’t know and this is what we are looking for! “He insisted that it was not really possible References According to him. ” Without a doubt, if we soon find out a fact externalIn the following decades, several methods will be implemented to detect a dynamic signature. We can then hope for an answer before the end of the twenty-first centurye century Researcher added. He dedicated his last book, Lands from other placesOn this question in the company of astrophysicist Bradford Smith.

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