The Seven Wonders of Exoplanets

The Seven Wonders of Planetary Defense

Il più vicino è un esopianeta che orbita intorno alla stella Proxima Centauri. La luce, che è la cosa più veloce nell’universo, impiega 4 anni ad arrivare a Proxima Centari. I nostri razzi viaggiano molto più lentamente della luce e quindi, con la tecnologia di oggi, impiegheremmo 135,000 ad arrivare a Proxima Centauri. Abbiamo bisogno di razzi più veloci! The closest is an exoplanet orbiting the star Proxima Centauri. Light, which is the fastest thing in the universe, takes 4 years to reach Proxima Centauri. Our rockets travel much slower than light and therefore, with today's technology, it would take us 135,000 to get to Proxima Centauri! We need faster rockets!

Le risque d’impact d’astéroïde est en fait un sujet fascinant. Pas tellement angoissant, puisque pour l’instant nous n’avons aucune menace, mais fascinant, parce qu’il porte sur des objets qui sont absolument excitants pour les scientifiques : ils évoluent dans un environnement qui est très différent de celui de la Terre et qui défie encore notre intuition. On l’a vu avec les missions récentes, la façon dont ils répondent aux actions externes qu’on leur fait subir, que ce soit un impact, que ce soit pour récolter un échantillon, est complètement contre intuitive. On est encore en train d’apprendre à interagir avec eux pour non seulement faire de la science, mais aussi s’en protéger. C’est plein de défis technologiques et scientifiques qui évidemment pour les scientifiques sont des sources d’excitation extraordinaires. The risk of an asteroid's impact is actually a fascinating subject. Not that much frightening, as for now we have not detected any threat, but fascinating, as it concerns celestial bodies, which are very exciting for scientists. Asteroids evolve in an environment completely different from the Earth's, which still defies our intuition. We saw on recent missions that the way they react to external actions that are applied to them, for instance, an impact or a sample collection, is entirely counter-intuitive. We are still in the process of learning how to interact with them, not only to do science but also to protect ourselves from them. This represents a lot of technological and scientific challenges that are extraordinarily exciting for scientists.

Comme tous les sujets qui portent sur une menace, la communication est extrêmement importante. On peut dire très vite n’importe quoi et il faut faire attention à ce que le public comprenne ce que l’on dit et puisse comprendre si la menace est réelle ou pas. Tout ça n’est pas facile, donc nous nous entrainons à communiquer avec le public cette notion de risque d’impact d’astéroïde et à être transparent, puisqu’on a besoin des amateurs pour suivre les objets dont les premiers calculs nous donnent une probabilité d’impact élevée. C’est très important de pouvoir en même temps expliquer qu’on a trouvé un objet qui semble dangereux, mais pour autant qui ne l’est pas encore tant qu’on n’a pas vérifié que sa trajectoire croise la Terre. C’est assez complexe, on a vu avec la pandémie [du COVID 19] que les scientifiques se contredisent et le public ne comprend plus rien. C’est ce qu’on cherche à éviter, on cherche à pouvoir communiquer un message cohérent et compréhensible, pour que les gens ne paniquent pas pour n’importe quoi. Similarly to any topic relative to a threat, communication is key. Not only can people say anything, but it is also essential to ensure that the public understands what is said and whether or not the threat is real. This is not easy, so we train ourselves to communicate with the public about the asteroid impact threat itself. We also train ourselves on transparency, as we count on amateur astronomers to follow celestial bodies for which the impact risk would be high according to our preliminary computations. It is imperative that we can explain if we have found an object that is a possible threat but is not yet until we have checked that its trajectory collides with the Earth's. All of this is pretty complex: the COVID-19 pandemic showed that the public is lost when scientists contradict each other. We want to avoid such a situation. Instead, we want to communicate a coherent and understandable message to prevent people from panicking for nothing.

Le risque d’impact d’astéroïde est un problème qui concerne le monde entier. Pour l’aborder, il faut avoir une réponse internationale coordonnée à ce problème. C’est pour cela que l’on a mis en place, sous l’égide de l’ONU, des groupes de travail qui s’intéressent à définir une réponse coordonnée. Si un objet nous arrive dessus, qui va monter la mission ? Qui va sauver le monde ? Tout ça doit se définir sans être improvisé parce que c’est assez complexe. Quelle industrie va faire la sonde qui va dévier l’astéroïde ? La bonne nouvelle, c’est que depuis quelques années, sous l’égide de l’ONU, nous avons des groupes de travail qui essaient de définir une réponse coordonnée avec le volet "prédiction," par des scientifiques, qui communique aux décideurs éventuellement qu’un objet nous arrive dessus ; le volet "agence spatiale," qui peut monter une mission pour dévier un astéroïde ; et même le volet "légal," puisqu’on ne fait pas n’importe quoi dans l’espace, donc tout ça doit être fait sous une forme légale qui est aussi définie. As the risk of asteroid impact concerns the entire planet, it is necessary to have a coordinated international response to it. This is why task forces aiming to give a coordinated response have been established under the supervision of the UN. If an asteroid is threatening the Earth, who will organize the mission? Who will save the planet? Given the complexity of such a response, all of these topics must be defined beforehand, without improvisation. Which company will build the probe to deviate the asteroid? The good news is that, under the supervision of the UN, task forces were created a few years ago and aim to give a coordinated response. The "prediction" task force, animated by scientists, communicates to decisionmakers that an asteroid is aiming toward the Earth. The "space agency" task force organizes a space mission to deviate the asteroid. Even a "legal" task force exists, as there are rules in space, and such an operation has to be done in agreement with the law, which is also defined.

Se protéger de l’impact d’un astéroïde nécessite que l’on puisse faire en sorte que si un objet nous arrive dessus il évite la Terre. Pour ça, il faut définir des techniques qui permettent de dévier la trajectoire d’un astéroïde qui nous arrive dessus. Il y a plusieurs méthodes qui marchent sur le papier, certaines sont d’ailleurs très élégantes, mais très complexes à mettre en œuvre. En gros, il y a quand même deux méthodes qui semblent un peu plus raisonnables. L’une, c’est la technique de "l’impacteur cinétique" (ce qui a été fait avec la mission Dart de la NASA, et qui va d’ailleurs être poursuivi avec la mission Era de l’ESA), qui consiste à envoyer un projectile à très haute vitesse sur un astéroïde pour taper dedans et le dévier de sa trajectoire. Ça parait simple, ça l’est pas tant, mais on a réussi avec la mission Dart. Une autre technique pourrait être ce que l’on appelle le "tracteur gravitationnel" : on met un satellite à proximité de l’astéroïde et avec la masse du satellite, on attire l’astéroïde vers lui et on lui évite sa trajectoire. Ce sont deux méthodes qui pourraient, éventuellement, nous aider à nous protéger du risque d’impact, dont l’une a déjà commencé à être testée avec succès. In order to avoid an asteroid impact, it is necessary to make the said asteroid avoid the Earth. To this aim, techniques must be designed to allow this deviation. Several theoretical methods are available, including very elegant ones, which are also very complex to operate. Two more reasonable methods are considered nowadays. First, the "kinetic impactor" (already operated by NASA with the Dart mission and planned by ESA with the Era mission) consists of sending a high-speed projectile on the asteroid; the impact will deviate from its initial trajectory. This is harder than it sounds, but it has already been done by the Dart mission. The second technique is the "gravitational attractor," where a satellite is orbited close to the asteroid, and the satellite's mass will pull the asteroid away from its initial trajectory. These two methods could protect the Earth from an asteroid impact, and one of them has already been successfully experimented with.

Pour se proteger du risque d’impact, comme on dit il vaut « mieux connaitre son ennemi ». Meme si les asteroides sont plutot nos amis, mais comme ici ils nous menacent on va les considerer comme un ennemi. Pour le connaitre il faut le caracteriser, c’est-a-dire comprendre quelles sont les proprietes physiques qui constituent ces objets. Est-ce que ce sont des roches monolithiques, des agregats, des aglomerats de roches ? Leur surface est-elle lisse ou s’agit-il plutot de graviers ? En fait, tout cela a des consequences sur nos strategies de deviations : si on veut devier un asteroide en le touchant, par exemple via un impact, il faut savoir si l’on a affaire a une eponge ou plutot a une roche tres dure. Cette caracterisation, on ne peut pas la faire depuis le sol terrestre. Il faut envoyer des missions spatiales qui auront pour but de les explorer sur place, parce que toutes les donnees dont on a besoin on ne sont pas disponibles depuis la Terre, et c’est ce qui constitue un immense defi. C’est d’ailleurs de qui offre des aventures spatiales absolument extraordinaires ! To protect ourselves from this impact risk, as it is said, "better know your enemy." Even if asteroids are usually our friends, as they threaten us, we will rather consider them here as a foe. It is necessary to characterize it to understand the physical properties that constitute those objects to know it. Are those rocks monolithic, aggregates or agglomerates? Is their surface smooth or instead made of gravel? In fact, that information has consequences for our diverting strategies. Suppose we want to deviate an asteroid by hitting it, for example, by impact. In that case, knowing if we face a sponge or a tough rock is necessary. We cannot do this characterization from the ground. It is necessary to send space missions that will explore them on-site because we cannot get that information from Earth, which is precisely what makes it a significant challenge. In the end, it also offers extraordinary space adventures!

Pour pouvoir se proteger du risque d’impact, il y a d’abord une chose a faire, c’est de decouvrir ces objets et de predire leur arrivee sur Terre. Cela n’est pas simple car ce sont de tous petits objets qui emettent une tres faible luminosite, donc cela necessite une tres grande couverture du ciel. On le fait depuis la Terre avec telescopes, et on a rescense la plupart des corps de plus d’un kilometre de diametre qui peuvent nous tomber dessus, mais aucun ne nous menacent sur l’ordre du siecle. A present, on essaye de faire l’inventaire des corps plus grand que 140km de diametre, ce qui est le seuil de taille pour une catastrophe a l’echelle d’un pays ou d’une region. On en connait a ce jour que 40%. Pour decouvrir les prochains 60%, depuis la Terre il faudrait plusieurs decennies meme avec les plus grands telescopes, c’est donc un grand defi. En fait, l’idee est de placer un telescope dans l’espace qui pourra en faire l’inventaire en 10 ans et c’est d’ailleurs l’objectif de la NASA avec la mission NEO Surveyor. To protect us from this impact risk, there is first a thing to do: discover those bodies and predict their arrival on Earth. It is not that easy because they are tiny objects emitting a very weak luminosity, demanding a vast sky covering. We do it from Earth with telescopes, and we have already discovered most of the objects more than a kilometer in diameter that could fall on us. Still, none of them are a threat for this century. Now, we try to make an inventory of bodies larger than 140km in diameter, which is the threshold size for a disaster of the size of a country or a region. We know so far about 40% of them. Discovering the next 60% from Earth would take decades, even by using the largest telescopes, so it is a consequent challenge. In fact, the idea is to place in space a telescope that can make this inventory within 10 years. This is NASA's objective with their mission NEO Surveyor.

Je suis Patrick Michel, astrophysicien, directeur de recherche CNRS à l’Observatoire de la Côte d’Azur en France. Voici les sept merveilles de la défense planétaire. Le risque d’impact d’asteroide est l’un des moins probables mais il a de hautes consequences. Il a un avantage : c’est le seul que l’on peut predire et eviter avec des moyens raisonnabes et realisables que l’on est en train de mettre en oeuvre. L’idee, c’est d’offrir aux futures generations un plan robuste de telle sorte qu’elles n’aient pas a improviser le jour probablement tres lointain ou un asteroide nous arrivera dessus. I'm Patrick Michel, an astrophysicist and director of research at CNRS at the Côte d'Azur observatory in France. These are the seven wonders of planetary defense. The asteroid's risk impact is one of the less likely to happen, but it has significant consequences. It has an advantage: it is the only one we can predict and dodge with reasonable and realistic means we are currently implementing. So the idea is to offer future generations a reliable plan so they would not have to improvise on the probably very distant day when an asteroid will come to us.

Il più vicino è un esopianeta che orbita intorno alla stella Proxima Centauri. La luce, che è la cosa più veloce nell’universo, impiega 4 anni ad arrivare a Proxima Centari. I nostri razzi viaggiano molto più lentamente della luce e quindi, con la tecnologia di oggi, impiegheremmo 135,000 ad arrivare a Proxima Centauri. Abbiamo bisogno di razzi più veloci! The closest is an exoplanet orbiting the star Proxima Centauri. Light, which is the fastest thing in the universe, takes 4 years to reach Proxima Centauri. Our rockets travel much slower than light and therefore, with today's technology, it would take us 135,000 to get to Proxima Centauri! We need faster rockets!

Non esistono super-Terre intorno al sole, ma sono tra gli esopianeti più comuni. Ci sono molti tipi di super-terre, tra cui “grosse” Terre, o “grosse” Veneri o piccoli Nettuni, ma anche pianeti più esotici come “i pianeti oceano”, interamente coperti da oceani in superficie, con molta più acqua di quanta abbiamo sulla Terra. There are no super-Earths around the sun, but they are among the most common exoplanets. There are many types of super-earths, including "large" Earths, or "large" Venus or small Neptunes, but also more exotic planets such as "ocean planets", entirely covered by oceans on the surface, with much more water than we have on Earth.

Non lo sappiamo con certezza, e vogliamo scoprirlo nei prossimi anni. Pensiamo sia dovuto a come si formano e alla loro storia. Per esempio, abbiamo scoperto molti “Giovi caldi” che orbitano molto vicino alla loro stella, ma si sono formati lontano e poi sono migrati successivamente. We don't know for sure, and we want to find out in the coming years. We think it's due to how they form and their history. For example, we have discovered many "hot Jupiters" that orbit very close to their star, but formed far away and then migrated later.

Dipende da quanto è distante il pianeta dalla stella. Per esempio la terra ci mette circa 365 giorni. Altri pianeti nel sistema solare ci mettono molti anni perché più distanti dal sole. Alcuni esopianeti, mettono meno di un giorno per completare un’orbita intorno alla propria stella, e sono così caldi che le rocce in superficie sono fuse. It depends on how far the planet is from the star. For example, the earth takes about 365 days. Other planets in the solar system take many years because they are further away from the sun. Some exoplanets take less than a day to complete an orbit around their star, and are so hot that the rocks on the surface are melted.

Circa 5000, ma il numero di pianeti conosciuti cresce ogni giorno. I primi esopianeti furono scoperti nel 1992 intorno ad una stella “morta”, da uno scienziato polacco e uno canadese (Wolszczan e Frail). Nel 1995 fu scoperto il primo esopianeta intorno ad una stella simile al nostro sole da due scienziati svizzeri (Mayor e Queloz), che hanno recentemente ricevuto il premio Nobel per questa scoperta. About 5,000, but the number of known planets is growing every day. The first exoplanets were discovered in 1992 around a "dead" star, by a Polish and a Canadian scientist (Wolszczan and Frail). In 1995, the first exoplanet around a star similar to our sun was discovered by two Swiss scientists (Mayor and Queloz), who recently received the Nobel Prize for this discovery.

Il sole è una stella, come quelle che brillano in cielo la notte. Le stelle sono fatte di idrogeno, l’elemento più comune nell’universo e sono caldissime, perché al loro interno l’idrogeno viene bruciato. Negli ultimi vent’anni abbiamo scoperto che quasi tutte le stelle hanno pianeti che orbitano intorno, come fa la Terra col il nostro sole. Li chiamiamo esopianeti. The sun is a star, like those that shine in the sky at night. The stars are made of hydrogen, the most common element in the universe and are very hot, because inside them the hydrogen is burned. In the last twenty years we have discovered that almost all stars have planets that orbit around them, as the Earth does with our sun. We call them exoplanets.

This episode features Deputy Director General of Institute of Space Astronautical Science, Dr Fujimoto on the international cooperation in space science missions. The interview was recorded in August 2023 as a part of JAXA Space Education Center’s internship program.

This episode features NASA’s Planetary Science Division Director, Dr. Lori Glaze! What is her typical day like? What is her message to the Artemis generation? And what is NASA doing next? The interview was recorded in May 2023 in Makuhari, Japan.

1．Asteroids and Meteorites 2．Why Collect Samples from Asteroids 3．Asteroids and Water 4．Asteroids and Gold 5．Star Fossils 6．Asteroids and Dinosaurs 7．DART and beyond ▶movie&script

1．Is Mars a planet like Earth? 2．Is or was Mars like Earth? 3．Is there life on Mars? 4．Is there water on Mars now? 5．How are we exploring Mars? 6．What are the missions of the future? 7．Can humans live on Mars? ▶movie&script