Hi ha vida més enllà de la Terra, al nostre sistema solar?
Is there life beyond Earth in our solar system?
Caram, quina pregunta més poderosa. Com a científics, com a planetòlegs, no ens ho havíem plantejat seriosament fins fa ben poc.
Wow, what a powerful question. You know, as a scientist -- planetary scientist -- we really didn't take that very seriously until recently.
Carl Sagan sempre deia: "Les afirmacions extraordinàries necessiten proves extraordinàries". Per afirmar que hi ha vida extraterrestre calen proves definitives, que siguin convincents i han d'estar per tot arreu perquè ens les creguem.
Carl Sagan always said, "It takes extraordinary evidence for extraordinary claims." And the claims of having life beyond Earth need to be definitive, they need to be loud and they need to be everywhere for us to be able to believe it.
Com comencem aquest viatge? El que vam decidir és buscar, primer, els ingredients necessaris per a la vida. Aquests ingredients són: aigua líquida, hem de tenir un dissolvent, no pot ser gel, ha de ser líquid. També hi ha d'haver energia. I matèria orgànica, allò de què estem fets. però també el que hem de consumir.
So how do we make this journey? What we decided to do is first look for those ingredients for life. The ingredients of life are: liquid water -- we have to have a solvent, can't be ice, has to be liquid. We also have to have energy. We also have to have organic material -- things that make us up, but also things that we need to consume.
Per tant, hem de tenir aquests elements en entorns durant molt de temps per poder estar segurs que la vida, quan comenci, pot sorgir, créixer i evolucionar.
So we have to have these elements in environments for long periods of time for us to be able to be confident that life, in that moment when it starts, can spark and then grow and evolve.
Us he de dir que al principi, quan observàvem aquests tres elements, no pensava que existissin fora de la Terra durant el temps suficient o en quantitats significatives.
Well, I have to tell you that early in my career, when we looked at those three elements, I didn't believe that they were beyond Earth in any length of time and for any real quantity.
Per què? Fixem-nos en els planetes interiors. Venus és massa calent, no hi ha aigua. Mart: sec i àrid. Tampoc té aigua. I més enllà de Mart, tota l'aigua del sistema està congelada.
Why? We look at the inner planets. Venus is way too hot -- it's got no water. Mars -- dry and arid. It's got no water. And beyond Mars, the water in the solar system is all frozen.
Però observacions recents ho han canviat tot. Ara ens centrem en els llocs adequats ho observem amb més atenció i podem començar a respondre la pregunta de si hi ha vida.
But recent observations have changed all that. It's now turning our attention to the right places for us to take a deeper look and really start to answer our life question.
Així que, si mirem el sistema solar, on n'hi podria haver? Ens centrem en quatre llocs. El planeta Mart i tres llunes dels planetes exteriors: Tità, Europa i la petita Encèlad.
So when we look out into the solar system, where are the possibilities? We're concentrating our attention on four locations. The planet Mars and then three moons of the outer planets: Titan, Europa and small Enceladus.
Sobre Mart, què? Repassem l'evidència. Primer, crèiem que Mart era similar a la Lluna. ple de cràters, àrid i desolat.
So what about Mars? Let's go through the evidence. Well, Mars we thought was initially moon-like: full of craters, arid and a dead world.
I fa uns 15 anys, vam començar missions per anar a Mart i comprovar si havia tingut aigua que canviés la seva geologia. Havíem de ser capaços de notar-ho. I vam quedar sorpresos només començar. Les imatges mostraven deltes, valls fluvials i fondalades que van existir en el passat. I, de fet, Curiosity que ja fa uns tres anys que recorre el planeta ens ha mostrat que és en un antic llit d'un riu, en què l'aigua hi fluïa ràpidament. I no durant poc temps, potser durant centenars de milions d'anys. I si tot hi era, també matèria orgànica, potser hi va sorgir vida.
And so about 15 years ago, we started a series of missions to go to Mars and see if water existed on Mars in its past that changed its geology. We ought to be able to notice that. And indeed we started to be surprised right away. Our higher resolution images show deltas and river valleys and gulleys that were there in the past. And in fact, Curiosity -- which has been roving on the surface now for about three years -- has really shown us that it's sitting in an ancient river bed, where water flowed rapidly. And not for a little while, perhaps hundreds of millions of years. And if everything was there, including organics, perhaps life had started.
Curiosity també ha perforat el terra i ha extret altres materials. Ens vam emocionar, quan ho vam veure. Perquè no era vermell, era de color gris, el planeta gris. Ho vam portar al vehicle, vam treure'n mostres i sabeu què? Vam trobar-hi matèria orgànica. Carboni, hidrogen, oxigen, nitrogen, fòsfor, sofre... hi havia tot això.
Curiosity has also drilled in that red soil and brought up other material. And we were really excited when we saw that. Because it wasn't red Mars, it was gray material, it's gray Mars. We brought it into the rover, we tasted it, and guess what? We tasted organics -- carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur -- they were all there.
Mart, en el passat, amb molta aigua, potser molt de temps, podria haver tingut vida, podria haver-hi sorgit, i haver crescut. I aquella vida encara hi és? No ho sabem.
So Mars in its past, with a lot of water, perhaps plenty of time, could have had life, could have had that spark, could have grown. And is that life still there? We don't know that.
Però fa uns anys vam començar a mirar alguns cràters. A l'estiu, apareixien línies fosques, baixant pels costats. Com més buscàvem, com més cràters miràvem, més línies trobàvem. N'hem trobat més d'una dotzena.
But a few years ago we started to look at a number of craters. During the summer, dark lines would appear down the sides of these craters. The more we looked, the more craters we saw, the more of these features. We now know more than a dozen of them.
Fa uns mesos, l'impossible es va convertir en realitat. Vam fer públic que ja sabíem què eren aquestes línies. És aigua líquida. Els cràters ploren a l'estiu. Baixa aigua líquida pels cràters. Què farem ara, ara que veiem l'aigua? Bé, ens diu que Mart té els ingredients per tenir vida. En el passat, pot ser que, en dos terços de l'hemisferi nord hi hagués un oceà. Té aigua líquida ara mateix. Aigua líquida a la superfície. Té matèria orgànica. Té les condicions correctes.
A few months ago the fairy tale came true. We announced to the world that we know what these streaks are. It's liquid water. These craters are weeping during the summer. Liquid water is flowing down these craters. So what are we going to do now -- now that we see the water? Well, it tells us that Mars has all the ingredients necessary for life. In its past it had perhaps two-thirds of its northern hemisphere -- there was an ocean. It has weeping water right now. Liquid water on its surface. It has organics. It has all the right conditions.
Què farem ara, doncs? Iniciarem un seguit de missions per buscar vida a Mart. I ara la cerca és més atractiva que mai.
So what are we going to do next? We're going to launch a series of missions to begin that search for life on Mars. And now it's more appealing than ever before.
Si ens endinsem en el sistema solar, hi trobem la petita lluna Encèlad. No és la zona habitable tradicional, aquesta àrea al voltant del sol. Està molt més allunyada. Això hauria de ser de gel sobre un nucli de silicat.
As we move out into the solar system, here's the tiny moon Enceladus. This is not in what we call the traditional habitable zone, this area around the sun. This is much further out. This object should be ice over a silicate core.
Però què vam descobrir? Cassini era allà des del 2006, i després d'uns anys, va passar per Encèlad i ens va sorprendre a tots. Encèlad envia capes d'aigua cap al sistema solar que cauen un altre cop sobre la lluna. Quin entorn més fabulós. Cassini fa uns mesos, va travessar la columna i va detectar partícules de silicat. D'on ve el silici? Ha de venir del fons de l'oceà. Saturn crea l'energia de la marea, atraient i estrenyent la lluna està desfent el gel, i creant un oceà. Però també ho fa al nucli.
But what did we find? Cassini was there since 2006, and after a couple years looked back after it flew by Enceladus and surprised us all. Enceladus is blasting sheets of water out into the solar system and sloshing back down onto the moon. What a fabulous environment. Cassini just a few months ago also flew through the plume, and it measured silicate particles. Where does the silica come from? It must come from the ocean floor. The tidal energy is generated by Saturn, pulling and squeezing this moon -- is melting that ice, creating an ocean. But it's also doing that to the core.
Per ara, l'única cosa que sabem que fa això a la Terra, com a analogia són les fumaroles hidrotermals. Les fumaroles es van descobrir al fons de l'oceà al 1977. Els oceanògrafs es van sorprendre molt. I ara n'hi ha milers sota l'oceà.
Now, the only thing that we can think of that does that here on Earth as an analogy ... are hydrothermal vents. Hydrothermal vents deep in our ocean were discovered in 1977. Oceanographers were completely surprised. And now there are thousands of these below the ocean.
Què hi descobrim? Les fumaroles hidrotermals, quan els oceanògrafs les observen, desborden vida, encara que l'aigua sigui àcida o alcalina, tant és. Les fumaroles són excel·lents per a la vida a la Terra.
What do we find? The oceanographers, when they go and look at these hydrothermal vents, they're teeming with life, regardless of whether the water is acidic or alkaline -- doesn't matter. So hydrothermal vents are a fabulous abode for life here on Earth.
I a Encèlad? Pensem que com que té aigua l'ha tingut durant molt de temps, i pensem que té fumaroles, potser amb la matèria orgànica adequada, és un lloc on hi pot haver vida. No només microbiana sinó també més complexa, perquè hi ha hagut temps per evolucionar.
So what about Enceladus? Well, we believe because it has water and has had it for a significant period of time, and we believe it has hydrothermal vents with perhaps the right organic material, it is a place where life could exist. And not just microbial -- maybe more complex because it's had time to evolve.
Una altra lluna, molt similar, és Europa. Galileo va visitar Júpiter al 1996 i va aportar dades sobre Europa. Sabem que Europa té un oceà sota la capa de gel. La missió Galileo ho va mostrar, però no hem vist que expulsés res. Però tampoc no ho vam buscar.
Another moon, very similar, is Europa. Galileo visited Jupiter's system in 1996 and made fabulous observations of Europa. Europa, we also know, has an under-the-ice crust ocean. Galileo mission told us that, but we never saw any plumes. But we didn't look for them.
El Hubble, fa un parell d'anys, mentre observava Europa, va veure columnes d'aigua que sorgien de l'hemisferi sud, igual que a Encèlad.
Hubble, just a couple years ago, observing Europa, saw plumes of water spraying from the cracks in the southern hemisphere, just exactly like Enceladus.
Aquests satèl·lits, que no són a la zona habitable habitual, que són a la zona exterior del sistema, tenen aigua líquida. I si hi ha matèria orgànica, potser hi ha vida.
These moons, which are not in what we call a traditional habitable zone, that are out in the solar system, have liquid water. And if there are organics there, there may be life.
Són uns descobriments extraordinaris perquè aquests satèl·lits han estat en aquestes condicions durant milers de milions d'anys. La vida a la Terra va començar després dels primers 500 milions, i mireu on som ara. Aquestes llunes són meravelloses.
This is a fabulous set of discoveries because these moons have been in this environment like that for billions of years. Life started here on Earth, we believe, after about the first 500 million, and look where we are. These moons are fabulous moons.
També observem un altre satèl·lit: Tità. Tità és una lluna enorme de Saturn. Probablement és més gran que Mercuri. Té una atmosfera extensa. És tan extensa... i és sobretot nitrogen, amb una mica de metà i età que hi has de mirar a través amb radar.
Another moon that we're looking at is Titan. Titan is a huge moon of Saturn. It perhaps is much larger than the planet Mercury. It has an extensive atmosphere. It's so extensive -- and it's mostly nitrogen with a little methane and ethane -- that you have to peer through it with radar.
A la superfície, Cassini hi ha trobat líquid. Hi veiem llacs de fet, en alguns llocs, gairebé de la mida del Mar Negre. Aquests llacs no són d'aigua líquida, són de metà. Si hi ha algun lloc al sistema solar, on la vida no és com la coneixem, on el substitut de l'aigua és un altre dissolvent, potser el metà, podria ser Tità.
And on the surface, Cassini has found liquid. We see lakes ... actually almost the size of our Black Sea in some places. And this area is not liquid water; it's methane. If there's any place in the solar system where life is not like us, where the substitute of water is another solvent -- and it could be methane -- it could be Titan.
Hi ha vida extraterrestre en el sistema solar? No ho sabem, encara, però ens hi estem apropant. Les dades que rebem són fascinants, i ens diuen, ens obliguen a pensar de manera completament diferent. Penso que anem pel bon camí. Que en 10 anys respondrem la pregunta. I si ho aconseguim, i la resposta és afirmativa, aleshores hi ha vida per tot el sistema solar. Penseu-hi. Potser no estem sols.
Well, is there life beyond Earth in the solar system? We don't know yet, but we're hot on the pursuit. The data that we're receiving is really exciting and telling us -- forcing us to think about this in new and exciting ways. I believe we're on the right track. That in the next 10 years, we will answer that question. And if we answer it, and it's positive, then life is everywhere in the solar system. Just think about that. We may not be alone.
Gràcies.
Thank you.
(Aplaudiments)
(Applause)