How NASA is answering the question: Are we alone? | Shawn Domagal-Goldman | TEDxMidAtlantic

About 20 years ago I was looking at the night sky with my little brother and we normally couldn't look at the night sky like the one I show on this slide because we grew up in Chicago and the lights of the city drowned out the stars, so most nights everything What we could do was count the stars, but on this night there was a lunar eclipse and we were there enjoying the majesty of the sky and my brother turned to me and said: do you think there is? There was no one around and I was not astrobiologist so I was a university student but I thought about it and I said well, there are many stars and at least some of those stars must have planets and at least some of those planets must have the conditions for life and yes, I guess at least there are some planets that They have life and I think that's how many of us think about that problem: Are we

alone

?

My job as an astrobiologist as a scientist thinking about that

question

is To turn that train of thought into hypotheses that we can test with data and observation, there are actually three hypotheses that I posed in my random musings to my brother: First, that stars are suns that have planets around them; second, that some of those planets have conditions that allow the global respiration of omnipresent biospheres and third, that some of those planets that could have those globally omnipresent biospheres actually have life. Three separate hypotheses. Today I'm going to talk about how in the twenty years since then the data that scientists specifically astronomers have collected. has revolutionized our understanding of those first two hypotheses and essentially confirmed that they are true and how in the next 20 years we are going to confirm the third hypothesis or fail in the attempt by obtaining a sample large enough to know that if there is no outer life we ​​know how

alone

we are, so I'm going to talk about the last 20 years in two ways or two properties of the planets the size of the planet and how much energy the planet gets from the star on the vertical axis of this line you have the size of the planet the big ones are at the top the small ones are at the bottom on the horizontal axis you have how much energy the planet gets from its host star.

I have hot planets to the left of the slide. I like to think of Be Lefty because that's how we always learn these things when we're mobile as kids, so imagine the star is on the left and things near that star are fried. Now I put the axes this way because this is related to the

question

of habitability. I'm not talking about any kind of life. I'm talking about a specific type of life. Remember, I want testable hypotheses. I want to know if there are planets out there that are not only inhabited, but so inhabited that life signals can be transmitted. detectable across interstellar space Now, if you ask me what kind of planets to look for, I actually think of a different analogy.

I think about if one of you in the audience that I don't know asks me where to find your keys, I would say look. in the pants that you are yesterday look in the jacket that you wore yesterday look under your coat rack and look in your nightstand and look under the sofa cushions now I tell you those things not because I know you have a sofa or pants or jacket but I tell you those things because that is where I lose my keys and that is where I find them well and so to look for life in other worlds as astrobiologists the first thing we do is look at all the places on Earth where there is life and in the hottest ones. in the driest and coldest places in the deepest places on Earth we have found life as long as there is liquid water in that environment and when I think about the global biosphere, that is why NASA has followed the water now strategy for these planets extrasolar that wanting a strong biosphere means we want global water that means we want oceans and that's where these axes come into play oh I should say I have the solar system here to scale Pluto is not here no no because Pluto is not a planet I think which yes it is, but it's just not on the scale that I'm showing, so the solar systems here we knew, if we knew these nine planets and if you get too close to the star, we know that it's too hot because those oceans of liquid water would boil , they would become a vapor atmosphere, we think this happened to Venus once, on the other hand, if you are too far away, you get too cold, now you are not too cold for life per se, right, there may be life on Enceladus . and Europa and these icy satellites on the outer solar technology, there could be life on Pluto, for all we know, and I hope we look for life on planets like this that have some reserve of water near or below the surface of those worlds, but that type of life is not the type of life that we will be able to detect with telescopes across the vast distances of interstellar space.

We need orbiters, we need rovers, we need samples from these worlds to look for life on them. We will not be able to see it on these planets because they do not have atmospheres to retain the signals that life will emit. I'll talk about that later, but you can be too cold not for life in general but for the kind of life we ​​want to pursue, omnipresent global life, you can also be too small if you are too small, you like the moon, the moon in It actually receives the right amount of energy to have oceans, but it has no atmosphere and If you don't have an atmosphere, you can't hold an ocean.

On the other hand, you can be too big and you can be like the gas giants in our outer solar system, which simply have too much atmosphere for water to be stable. the surface but among those four between the two hot ones and the two cold ones the two big ones and the two small ones you have this blue box is the happy place are the planets of the habitable zone that we discovered that have properties that fall inside this box are ones that could have stable global oceans on the surface for long periods of time over geological and astronomical periods of time, those are the worlds that we think could have large, robust biospheres that would emit signals that we could detect from very far away and use them to test the hypothesis of that we are alone or that we are not alone, so this is where we were in 1996, we had nine planets back then in our solar system, we know of six worlds beyond our solar system and if, like me, you think that Pluto is a planet and You're a little upset about not being called a planet anymore, don't worry because we now have many more planets that we know about beyond our solar system.

More than a thousand have been confirmed in the last 20 years thanks to the hard work and tenacity of engineers developing instruments on spaceflight telescopes that have detected hundreds, actually more than a thousand worlds beyond our solar system, and this not even It doesn't even include the candidate planets that we haven't confirmed yet, but we're pretty sure that our planets if we include those in the chart this is what it looks like this is a dramatically different scenario than the one I showed two slides ago where we knew of fewer planets beyond our solar system that within it we have orders of magnitude more data than We have also gotten better at detecting the smallest planets we know now, planets that are about the same size as Earth and that get about the same amount of energy from their star host than the one we get from the Sun;

In other words, we know the planets. that are in that happy blue box that could have oceans, ubiquitous global biospheres, now almost all of the data that I just showed comes from the Kepler spacecraft, which is a telescope that is orbiting the Earth right now, it's actually a own orbit around the Sun, is in space and has been searching for most of its mission in a patch of sky the size of your hand. Now I say that because it means that most of the points I showed in that diagram came from a patch of sky this size, so if you go out tonight and look at the night sky, raise your hand and realize that there are thousands of worlds hidden away. behind your hand that is different it is a different place it is a different night sky than the one we had 20 years ago we have also learned to expect the unexpected we know it super The planets Earth larger than the Earth and smaller than Neptune we do not have them in our solar system, we thought they would be rare, so of course they turned out to be one of the most common types of planets that we knew of these planets like Kepler 16b. that it would have a poetic double sunset because it is a planet that orbits two stars in the center of the system, just like a sunset, one sunset so does the other and astronomers thought that was impossible, well, the Most astronomers thought it was impossible.

I always thought these Planets existed, but that's because I was looking at a different source of literature than theirs, so we have to expect the unexpected, we also have to look for visionaries in science fiction and other places to get some motivation sometimes and now, when I look at the night sky. As a result of all this, if I'm there with my brother, first of all, look at it differently, because if I'm doing it now with my brother and sister, I'll also do it with our daughters and probably Looking down more than up , but now I also know that the night sky is different.

I know things about it that we didn't know as a society 20 years ago instead of saying well there are a lot of stars out there and surely some of them have planets. I can say that there are a lot of stars out there and if we count them we know that on average, we calculate the numbers, each star on average has a planet and about 1 in 5 stars has a planet that has the conditions that could host global biospheres, so that if I count 10 stars and there are many more than 10 in this line, by counting 10 stars, I counted 10 planets on two planets that could host life, so the first two hypotheses have been confirmed, but the third has not. and that's what the next 20 years are about now there are three types of challenges that we will have to overcome to change our view of the night sky again a technological challenge a scientific and social challenge this is not a mistake slide I What I'm showing you has a pale blue dot which is what we want to find and what we want to analyze, but you're probably having trouble seeing it right now because you're blinded by the white photons coming from the rest of the On this slide, the planets are faint stars, they're bright, In fact, the light from the planets that we want to capture is actually just reflected light from the host star and the planets and stars are next to each other and, as a result, for every photon we get. of the planet we want to see we are going to get a billion photons from the star unless we cancel them and we have to cancel those billion photons from the star without canceling that precious photon of the pale blue dot that we have.

What we are looking for is a very difficult technological problem now, even if we find that that pale blue dot will still be extremely pale and difficult to see, you still may not be able to see it, it is there if you don't and To see faint things, If we see these worlds, they will be some of the faintest, faintest things we have ever observed with any instrument ever built, and to see faint things, there are two things you can do. Are you on a camera? Now that you are taking pictures, you can expose for longer or you can get a bigger camera.

As astronomers, we like to build bigger telescopes. The Hubble Space Telescope has been in flight for 25 years, which is a wonderful technological achievement on its own, it's about 2.4 meters wide, I'm about 1.9 meters tall, so I don't know from here to the ground, from my hand to the ground, how big it is around Hubble. The James Webb Space Telescope will be about a factor of three larger than Hubble. but we think that if we want to get a really good sample size and answer the question of whether we are alone or at least know how alone we are, we need a larger telescope than the one the web is going to give us and we need that too. technology to cancel starlight and that is something that is now called HD ST, which stands for High Definition Space Telescope, don't worry about memorizing because I'm sure the name will change at least two or three times before this happen. it actually flies, but the thing here, the reason I point this out is because we didn't count on miracles.

I have nothing against miracles. I told you. I grew up in Chicago. I'm a Cubs fan. I grew up with miracles. Okay, and I hope. for one this October, but at NASA we're not in the business of relying on them, we're in the business of constant technological progress taking advantage of the things we're already doing or have already done, so we look at Hubble and how it's been in operation for 25 years. We look at the Webb telescope and how it teaches us to build larger telescopes. We look at Kepler, which I mentioned before, and another mission called tests, which will do similar science to Kepler and tells us whatwhat's up.

There are in the universe in terms of the populations of planets that we are going to observe and we are looking at the first W telescope that will begin to be built after Webb is finished and that will begin to develop the technologies to solve that difficult problem of blocking light from the stars without losing any precious photos from the planet, so that's the first challenge and if we overcome it we can build something like this and get Carl Sagan's pale blue dot and Sagan was very poetic about it, he talked about how everything that Have I ever done as individuals or as a society or as a biosphere on this planet has happened in this small point and it's really beautiful to think about it, but when I think about it as a scientist and I think I have to look at that point. and tell it whether there is life or not in it and approach it with a certain scientific rigor, that is a difficult problem;

That is the scientific challenge that now arises. Let's solve it: not only are we going to have that pale blue dot, we are going to divide that blue color into a complete spectrum of colors of that world and we are going to look for the signal. -fingerprints of certain gases such as oxygen and methane. I rely a lot on oxygen and methane as biosignatures. The reason is that it's like college students on pizza. Okay, if there are a lot of college students in a room and there's pizza in the room, do you know anyone? just hand over the pizza because college students eat it pretty fast.

From there, you can make sure there is a pizza delivery restaurant nearby because, let's be honest, students don't make their pizza at home, so with the presence of college students and pizza together, you can figure it out. that there is a pizzeria nearby similarly, if there is oxygen and methane and a planet together, you know that there is life there or at least we think there is life there and the reason is because oxygen and methane also destroy each other quickly and by that must be recovered. them quickly and the best replenishment mechanism is life there are ways to produce oxygen without life there are ways to produce methane without life but having them together in the atmosphere is almost impossible unless you have biology producing those gases on the surface and a imprint on the color spectrum of the planet, this is actually the spectrum of the Earth here and you can see the presence of oxygen and methane and other gases in that color spectrum.

Now I'm a little worried about this because 20 years ago when I was chatting with my brother and when astronomers announced the discovery of the first planet around a star similar to the Sun, we also announced from a different part of the agency evidence of life beyond On Earth, we found evidence recovered in these fossilized microbes from a rock that used to sit on the Martian surface immediately afterwards and certainly in the 20 years since then there has been a lot of pushback from the scientific community. I think the consensus now would be that the evidence on this slide in this image and in this rock for life is just as well described by non-biological processes, which tells us that although life could have been present in that rock, there is no solid evidence of life in that rock and that worries me, I don't want to call the President and say Madam President.

I found evidence of life and then I asked him to call a press conference and then six months later I got in my face and the other people on that team. I want to be sure at least as sure as I can know and do it. Well, it's going to require something broader than just me and my team, it's going to require us talking to people from other disciplines, biologists, chemists, planetary scientists, people who study our own climate on this planet and how the biosphere interacts with our atmosphere. here. We need to talk to the space physicists who understand how stars drive the planetary climate and biology on the planet's surface that we need.

This is a problem that everyone must work on. We haven't figured it out yet, but we have something in the works. Called Nexus, which you'll be hearing about for years to come, the goal of Nexus is to break the pipelines that we've set up in the past to fund detailed questions to bring together the people who study those detailed questions with those different perspectives. Now, if we do that and we do it, I think the technical aspect will be there, but there is another challenge that we have to overcome that I think will help us overcome these other two challenges, and that's when I walk into a room that works.

On one of these missions, when I go to a conference, to be honest, I see a lot of people who look like me and that is a separate challenge in itself. I know a lot of geniuses who look nothing like me, so the fact that most of the people I work with look like me tells me that we are missing a lot of geniuses in that room. It's also important because research has shown that diverse teams do better and get better answers more quickly and efficiently than teams. without diversity, so in addition to losing some geniuses, our team is simply not as strong as it could be when a group of people have the same background as me, some of the same privileges that I have, and are therefore predisposed to think like I do in making the same mistakes that I'm going to make, so we need academic diversity, we need people from different academic backgrounds on this team and in these efforts, but we also need better cultural and life diversity in these missions, okay , if we can overcome it. that challenge we will be able to build a better telescope if we can build a better telescope we will also obtain the data we need we will be able to analyze it to look for signs of life and that will put us in a place where in 20 years I hope to be looking at the night sky with my brother and our children and when they ask me that we are alone I don't want to just pontificate about what could be out there I want to look at them and say yes, that star over there is another Sun that has a planet in orbit around it that has the conditions suitable for life and we have observed signs of life in that world that I want to look at. in that night sky 20 years from now and I hope you're all watching it with me, thank you