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

so about 20 years ago I was looking with my little brother at the night sky and we didn't normally get to look at the night sky like the one I'm showing on this slide because we grew up in Chicago and the lights from the city drowned out the stars so most nights all we could do is count the stars but on this night there was a lunar eclipse and so we were out there enjoying the majesty of the sky and my brother turned to me and he said do you think there's anybody out there and I wasn't an astrobiologist then I was a college student but I thought about it and I said well there's a lot of 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 so yeah I guess at least there's a few planets out there that have life and I think that's how a lot of us think about that problem of are we alone my job as an astrobiologist as a scientist that thinks about that question is to turn that train of thought into hypotheses that we can test with data and observation there's really three hypotheses I made there in my random ponderings to my brother first that stars are Suns that have planets around them second that some of those planets have conditions that would allow for global breathing pervasive biospheres and third that some of those planets that could have those global pervasive biospheres actually do have life three separate hypotheses today I'm going to talk about how in the twenty years since then the data that scientist specifically astronomers have collected has revolutionized our understanding of those first two hypotheses and essentially confirmed them to be true and how in the next 20 years we're going to confirm the third hypothesis or or fail trying by getting a large enough sample to know that if there isn't life out there we know how lonely we are so I'm going to talk about the last 20 years in two ways or in two properties of 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 how big the planet is big ones are on top little ones on the bottom on the horizontal axis you have how much energy the planet gets from its host star I have hot planets on the left of the slide I like thinking about the Sun be the leftist because that's how we always learn these things as mobiles as kids so just imagine the star being on the left and things close to that star being fried now I put the axes in this way because this is related to that habitability question I'm not talking about any kind of life I'm talking about a specific kind of life remember I want testable hypotheses I want to know if planets are out there that not just are inhabited but are so pervasively inhabited that the signals from life can be detectable across interstellar space now if you ask me what kind of planets to look for actually think of a different analogy I think about if one of you in the audience who I don't know ask me where to find your keys I would say well look in the pants you are yesterday were look in the jacket you wore yesterday look under your coat rack and look on your nightstand and look under the couch cushions now I tell you those things not because I know you have a couch or pants or jacket but I tell you those things because that's where I lose my keys and that's where I find them right and so for looking for life on other worlds as astrobiologists the first thing we do is we look at all the places on earth that there's life and in the hottest in the driest and the coldest in the deepest places on earth we have found life so long as there's liquid water in that environment and so when I think about global biosphere that's why NASA has had this follow the water strategy now for these extrasolar planets that we want a strong biosphere from that means we want global water that means we want oceans and that's where these axes come into play oh I should say I got the solar system here for scale Pluto's not on here not not because Pluto's not a planet I think it is but it's just not on the scale that I'm showing okay so the solar systems on here we knew if we know of these these nine planets and if you get too close to the star we know that it's too hot because those liquid water oceans would boil they'd turn into a steam atmosphere we think this happen to Venus once upon a time conversely if you're too far away you get too cold now you're not too cold for life per se right there can be life on Enceladus and Europa and these icy satellites in the outer solar tech there might be life on Pluto for all we know and I hope we look for life on planets like this that have some reservoir of water near or under the deep under the surface of those worlds but that kind of life is not the kind of life that we're going to be able to detect with telescopes across the vast distances of interstellar space we need orbiters we need Rovers we need samples back from these worlds to look for life on them we're not going to be able to see it in these planets because they don't have atmospheres to retain the signals that life is going to give off I'll talk about that later but you can be too cold not for life in general but for the kind of life that we want to look for the global pervasive life you can also be too small if you're too small you like the moon the moon actually gets the right amount of energy to have oceans on it but it has no atmosphere and if you don't have an atmosphere you can't retain an ocean on the flipside of that you can be too big and you can be like the gas giants of our outer solar system which just have too much atmosphere for water to be stable at the surface but between those four between the two hot and the two cold the two big and the two small you've got this blue box it's the happy place it's the habitable zone planets that we discover that have properties that fall inside this box are ones that could have global oceans stable at the surface for long periods of time for geological and astronomical amounts of time those are the worlds that we think could have big robust biospheres that would give off signals we could detect from far away and use that to test the hypothesis of are we 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 Pluto is a planet and you're a little bit of upset at not being called a planet anymore don't worry because we now have a lot more planets that we know of beyond our solar system over a thousand have been confirmed in the last 20 years from the hard work and the tenacity of the engineers developing instruments in spaceflight telescopes that have detected hundreds actually more than a thousand worlds beyond our solar system and this doesn't even include the planet candidates that we haven't yet confirmed but we're pretty sure our planets if we include those on the chart this is what it looks like this is a dramatically different scenario from the one I showed two slides ago where we knew of fewer planets beyond our solar system than we did inside of it we have orders of magnitude more data we've also gotten better at detecting the smaller planets we've now know of planets that are about the same size as Earth that get about the same amount of energy from their host star that we get from the Sun in other words we know of planets that sit in that blue happy box that could have oceans pervasive global biospheres now almost all of the data I just showed comes from the Kepler spacecraft that's a telescope that's orbiting the Earth right now actually sort it's an own orbit around the Sun it's in space and it's been looking for most of its mission at one patch of sky about the size of your hand now I say that because it means that most of the dots I showed on that diagram came from a patch of sky about this big so if you go out tonight you look at the night sky put your hand up and realize that there's thousands of worlds hiding behind your hand that's different it's a different place it's a different night sky than we had 20 years ago we also have learned to expect the unexpected we know super Earths planets bigger than Earth and smaller than Neptune we don't have in our solar system we thought they would be rare so of course they turned out to be one of the most common kinds of planets out there we knew of these planets like Kepler 16b which would have a poetic double sunset because it's one planet orbiting two stars at the center of the system so as the one sunset one sunset so does the other one and astronomers thought that was impossible well most astronomers thought it was impossible I always thought that these planets existed but that's because I was looking at a different source literature than they were so we have to expect the unexpected we also have to look to visionaries in science fiction and other places for for some motivation sometimes and now when I look at the night sky as a result of all this if I'm there with my bro well first of all look at it differently because if I'm doing it now with my brother and my sister I'm doing with our daughters as well and I'm probably looking down more than I'm looking up but I also now 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's a lot of stars out there and surely some of them have planets I can say there's a lot of stars out there and if we count them we know that on average we crunch the numbers every 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 if I count 10 stars and there's a lot more than 10 on this line by count 10 stars I counted 10 planets in two planets that could Harbor life so those first two hypotheses have been confirmed but that third one hasn't and that's what the next 20 years are about now there's three kinds of challenges we're going to have to overcome to change our view of the night sky again a technological challenge a scientific challenge and a societal one this is not a mistake the slide I'm showing you has a pale blue dot on it which is what we want to find and what we want to analyze but you're probably having trouble seeing it right now because it's you're blinded by the white photons coming from the rest of this slide planets are dim stars are bright in fact the light from the planets that we want to grab is actually just reflected starlight from the host star and the planets and the stars are right next to each other and as a result for every photon we get from the planet we want to see we're going to get 1 billion photons from the star unless we cancel them out and we have to cancel out those billion photons from the star without cancelling out that one precious photon from the pale blue dot we're looking for that's a very hard technological problem now even if we figure that out that pale blue dot is going to still be extremely pale and it's hard to see you still might not be able to see it it's right there if you don't and to see dim things if we see these worlds they will be some of the dimmest faintest things we've ever observed with any instrument ever built and to view faint things there's two things you can do you can you're in a camera if you're taking pictures now you can expose for a longer time or you can get a bigger camera so as astronomers we like to build bigger telescopes the Hubble Space Telescope has been in flight for 25 years which is a marvelous technological achievement on its own it's about 2.4 meters across I'm about 1.9 meters high so I don't know about here to the ground from my hand to the ground is about how big around Hubble is the James Webb Space Telescope is going to be about a factor of three larger than Hubble but we think that if you want to get a really good sample size and answer the question of are we alone or at least know how lonely we are we need a bigger telescope than even what the web is going to give us and we also need that technology to cancel out the Starlight and that's something that right now is called the HD ST which stands for the 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 thing ever actually flies but the thing here the reason I point this out is because we were not counting on miracles I have nothing against miracles I told you I grew up in Chicago I'm a Cubs fan I was raised on miracles okay and I'm hoping for one this October but but in NASA were not in the business of relying on them we're on the were in the business of steady technological progress leveraging the things that 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 bigger telescopes we look at Kepler which I mentioned earlier and another mission called tests which is going to do similar science to Kepler that tells us what is out there in the universe in terms of the planet populations that we're going to be looking at and we're looking at the W first telescope which will start building after Webb is finished that's going to start developing the technologies to do that difficult problem of blocking out the Starlight without losing any precious photons from the planet so that's the first challenge and if we overcome it we can build something looks like this and get Carl Sagan's pale blue dot and Sagan was very poetic about this he talked about how everything that we've ever done as individuals or as a society or as a biosphere on this planet has happened on this one tiny dot and that's really lovely to think about but when I think about it as a scientist and I think I have to look at that dot and tell you whether or not there's life on it and deal with some scientific rigor that's a hard problem - that's the scientific challenge now the way we're going to solve that is we're not just going to have that one pale blue dot we're going to split that blue color up into a full spectrum of colors from that world and we're going to look for the tell-tale fingerprints of certain gases like oxygen and methane I rely on oxygen and methane a lot as bio signatures the reason is it's like college students in pizza ok if there's a lot of college students in a room and there's pizza in the room you know someone just deliver the pizza because the college students eat it pretty quickly from that you can ascertain that there's a pizza delivery restaurant nearby because let's be honest students don't make their home pizza so by the presence of college students and pizza together you can figure out that there's a pizza restaurant nearby similarly if there's oxygen and methane and a planet together you know that there's life there or at least we think that there's life there and the reason is because oxygen and methane also destroy each other rapidly and so you have to replenish them rapidly and the best replenishment mechanism is life there's ways to make oxygen without life there's ways to make methane without life but to have them in the atmosphere together is almost impossible unless you've got biology making those gases at the surface and it would have a imprint on the planets spectrum of colors this is actually Earth's spectrum here and you can see the presence of oxygen and methane and other gases in that spectrum of colors now I worry about this a little bit because 20 years ago and when I was chatting with my brother and when astronomers were announcing the discovery of the first planet around a sun-like star we were also announcing from a different part of the agency evidence for life beyond Earth we found reclaimed evidence in these fossilized microbes from a rock that used to sit at the Martian surface now immediately thereafter and certainly in the 20 years since then there's been a lot of pushback from the scientific community I think the consensus now would be that the evidence in this slide in this picture and in this rock for life is just as well described by non-biological processes so that tells us that although life could have been present in that rock there is no solid evidence for life in that rock and I worry about that I don't want to call up the President and say Madam President I found evidence of life and then and have her call a press conference and then six months later have egg on the face of myself and the other people on that team I want to know for sure at least as sure as I can know and to do that 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 that study our own climate on this planet and how the biosphere interacts with our atmosphere here we need to talk with the space physicists that understand how stars drive planetary climate and biology at the surface of the planet we need this is this is an all-hands-on-deck problem now we haven't solved that yet but we have something in the works called Nexus you'll be hearing about for the next few years the whole point to Nexus is to break down the pipes that we've set up in the past to fund detailed questions to bring people that study those detailed questions together with those different perspectives now if we do that and we do that the technical thing I think will be there but there's one other challenge that we need to overcome that I think will help us overcome these other two challenges and that is when I walk into a room that works on one of these missions when I go to a conference to be frank I see a lot of people that look like me and that that that is a separate challenge in itself I know a lot of geniuses that don't look anything like me and so the fact that most of the people I work with look like me tells me we're missing a lot of geniuses in that room it also is important because research has shown that diverse teams do better they get to better answers more quickly and more efficiently than teams without diversity so in addition to missing some geniuses our team just isn't as strong as it could be when a bunch of people have the same backgrounds as me some of the same privileges that I have and so are predisposed to thinking like me 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 on these these endeavors but we also need better cultural and just over a life diversity on these missions okay so if we can overcome that challenge we're going to be able to better build a better telescope if we can build a better telescope we're also going to get the data we need we're going to be able to analyze it to look for signs of life and that's going to put us in a place where 20 years from now I hope to be looking up with my brother and our kids at the night sky and when he asks me we're alone I don't want to just pontificate about what could be out there I want to look at them and say yeah that star right there that is another Sun that has a planet in orbit around it that has the right conditions for life and we've observed signs of life on that world I want to be looking at that night sky in 20 years and I hope you're all looking at it with me thank you

Channel: TEDx Talks

Views: 169,439

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Keywords: TEDxTalks, English, United States, Life, Big Data, Biosphere, Rocket science, Science, Space, Technology

Id: Lp7BL-UI0Rw

Length: 17min 12sec (1032 seconds)

Published: Fri Apr 08 2016