- 2 days ago
Senior Scientist for Astrobiology Strategy at NASA David Dr. Grinspoon joins WIRED to answer the internet's burning questions about astrobiology. Where do astrobiologists work? What is the probability that humans aren't alone in the universe? Have there been credible UFO sightings documented? What REALLY goes on at Area 51? Was there ever life on Mars? Answers to these questions and many more await on Astrobiology Support.
Director: Lisandro Perez-Rey
Director of Photography: LaDawn Manuel
Editor: Paul Tael
Expert: David Grinspoon
Line Producer: Jamie Rasmussen
Associate Producer: Brandon White
Production Manager: Peter Brunette
Production Coordinator: Rhyan Lark
Casting Producer: Nick Sawyer
Camera Operator: Karl Riemer
Sound Mixer: Corey Johnson
Production Assistant: Isaiah Baylor
Post Production Supervisor: Christian Olguin
Supervising Editor: Erica DeLeo
Additional Editor: Samantha DiVito
Assistant Editor: Billy Ward
Director: Lisandro Perez-Rey
Director of Photography: LaDawn Manuel
Editor: Paul Tael
Expert: David Grinspoon
Line Producer: Jamie Rasmussen
Associate Producer: Brandon White
Production Manager: Peter Brunette
Production Coordinator: Rhyan Lark
Casting Producer: Nick Sawyer
Camera Operator: Karl Riemer
Sound Mixer: Corey Johnson
Production Assistant: Isaiah Baylor
Post Production Supervisor: Christian Olguin
Supervising Editor: Erica DeLeo
Additional Editor: Samantha DiVito
Assistant Editor: Billy Ward
Category
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TechTranscript
00:00What is Area 51 actually used for?
00:03Well, I could tell you, but then I'd have to kill you.
00:06No, just kidding.
00:08I'm astrobiologist David Grinspoon from NASA.
00:11Let's answer your questions from the internet.
00:13This is Alien Support.
00:19Disgruntled Hermit asks,
00:21what's the most interesting exoplanet you've read about?
00:24If I had to pick a favorite that we found so far,
00:27it would be the planets in the TRAPPIST-1 system.
00:29There are seven planets in the system
00:31that we've identified so far,
00:33and probably about three of them are potentially habitable.
00:36And by the way, the TRAPPIST system
00:38is only 40 light years away,
00:39which if you consider that our galaxy
00:41is 100,000 light years across, that's relatively close.
00:45I have a sort of chart here,
00:46and you can see the habitable zone of the TRAPPIST system
00:49with several potential planets in it
00:51compared to the habitable zone of our solar system
00:54on the bottom, which has Earth,
00:55and then, you know, sort of possibly Venus and Mars
00:58on the edges of habitability.
00:59And by the way, the TRAPPIST system here,
01:02it's a cooler star than our sun.
01:03It's a red dwarf,
01:04and so the planets are clustered very close.
01:06But imagine what it would be like for life evolving
01:09on a system with multiple habitable planets
01:12nearby one another.
01:13Meteorites occasionally get blasted off of one planet
01:16and land on another.
01:17We have pieces of Mars here on Earth.
01:19So if you have a habitable planet with life
01:21and another planet that could be habitable,
01:23you could imagine life spreading easily.
01:26Jabalanki asks,
01:28Are aliens real?
01:29Well, my thought is that aliens are real.
01:31There are probably something like 30 billion habitable planets
01:34in our own galaxy.
01:36And so even if a small fraction of those have an origin of life,
01:39there's lots of life in our galaxy.
01:41And the more we study Earth and its origins,
01:43we haven't found anything that's sort of magical
01:45or so special about Earth
01:47that those things shouldn't be happening elsewhere.
01:50So if you're asking me,
01:51do I think aliens are real?
01:52Yes.
01:53If you're asking me, do I know scientifically?
01:55I'll say not yet,
01:56but we're on the road to find out.
01:58Here's a question from Quora.
02:00How accurate is Arrival scientifically?
02:02I really liked the movie Arrival.
02:04I'm watching this scene here with this astrobiologist
02:07lost in wonder and awe and a little bit of terror
02:10encountering this alien.
02:11We talk about convergent evolution,
02:13that evolution on other worlds
02:15would find some of the same solutions.
02:18So the idea that they have something that's like fingers
02:20for grasping, that makes sense.
02:22The idea that they would have this kind of symmetry,
02:24just like we have bilateral symmetry,
02:26they look vaguely squid-like, vaguely octopi-like.
02:29I wouldn't be surprised if we saw complex aliens,
02:32if they looked somewhat familiar,
02:34but not exactly like any organism we had seen before,
02:37because again, they'll be responding to the same
02:39over all kinds of evolutionary forces.
02:41And then you have the other factor
02:43where she's trying to communicate
02:44and this alien is doing this weird kind of circular writing
02:47and it turns out that they are trying to communicate with us
02:52and they're as equally puzzled by us.
02:54That makes sense because I think there's this whole idea,
02:56something called incommensurability,
02:58that it might really be hard to communicate
03:00because they might have very different kinds of cognition,
03:03very different notions of reality and time.
03:05So I find this alien very convincing.
03:09Utopia Circle asks,
03:11how exoplanets are discovered?
03:12You can't directly observe the planet
03:14because they're too dim and too far away,
03:16but you can notice what the planet is doing to the star.
03:19So as a planet orbits a star,
03:22because of the gravitational pull of that planet,
03:24the star actually wobbles a little bit.
03:26So that star is wobbling
03:28because there's a planet around it,
03:29even though you can't see the planet.
03:30So some of the time,
03:32the star is coming towards your telescope
03:34and some of the time,
03:35the star is coming away from your telescope.
03:38We call that a Doppler shift.
03:39When it's coming towards you,
03:41the frequency shifts to a higher frequency.
03:44Blue, when it's coming away from you,
03:45it shifts to a lower frequency, red.
03:48And so our instruments got good enough
03:50to detect that slight change,
03:52that rhythmic change from blue to red to blue to red.
03:55It's a very, very tiny shift in wavelengths.
03:58And that was the first sign.
04:00And then later on, there was a new technique.
04:03That's called the transit method.
04:04When a planet passes directly in between you and the star,
04:09you can notice that little bit of dimming of starlight.
04:12It's very tiny
04:13because planets are small compared to the star.
04:15But if you have a very sensitive measurement
04:17of the light of that star over time,
04:19when a planet passes just in front of it,
04:21the star will dim a little bit.
04:23And so if you watch the light curve over time of that star,
04:26it'll wobble up and down and up and down and up and down.
04:28So you're not so much seeing the planet
04:30as noticing that the planet is blocking the star a little bit,
04:33causing it to periodically dim.
04:35It only works when the geometry is right.
04:37If it's a little bit above or a little bit below
04:40the direct line between your telescope and that star,
04:43you'll miss it.
04:44So only about 5% of stars have planets oriented
04:47in the right plane, the right direction
04:49to use that transit method.
04:50But when things are lined up right, it's very sensitive.
04:53So that has allowed us now, especially with space telescopes,
04:56like there was an instrument called Kepler
04:58that was designed to use the transit method
05:01to find lots of exoplanets.
05:02And that was really what revealed to us
05:05that most stars in the universe have planets.
05:08Sohat Virgo asks,
05:10where do astrobiologists work?
05:12How hard is it to get a job in astrobiology?
05:14So astrobiologists work a lot at universities.
05:18Some of them work in government labs.
05:20Some of us build spacecraft and send them out
05:24to observe other planets.
05:25Some of us do field work and study exotic locations,
05:29go on expeditions where there's extreme life
05:31to understand the limits of life
05:33and look for some of the earliest signs of life.
05:36This is a rock called a stromatolite.
05:38This one comes from Western Australia
05:39and is about 2.7 billion years old.
05:43And if you look in close, you see this rock
05:45is made up of layers.
05:46And what we've learned is that those layers
05:48are from ancient microbial mats.
05:50Some of the earliest life on earth
05:52that formed these layers on what was then the seafloor.
05:56Microbes, single celled organisms,
05:58using the energy of sunlight,
06:00using different kinds of nutrients flowing in the seawater
06:03and organizing themselves into these layers.
06:06I'm at your mom's house asks,
06:08what is taking NASA so long to find them aliens?
06:11What active missions are they doing?
06:13Well, it's a big universe out there,
06:15but we're working on it.
06:16Obviously, we have rovers on Mars
06:18searching for the signs of ancient life.
06:20So we have a mission now on its way to Europa,
06:23a moon of Jupiter that is home
06:25to a vast ocean of liquid water.
06:27So we have a mission called Europa Clipper,
06:28orbiting the Jupiter system and making close passes by Europa
06:32in the early 2030s, helping us to understand
06:35if that ocean is habitable.
06:37What's the temperature, the pressure,
06:38what are the flows of nutrients and so forth?
06:41Is that ocean a place that could support life?
06:43And if it is, that would motivate us
06:46to send missions in the future
06:47that would land on the surface
06:48and maybe even tunnel under the ice in submarines
06:51to look directly for life on Europa.
06:53We also have a mission called Dragonfly
06:56that's going to launch in a few years and go to Titan.
06:59Titan is a moon of Saturn.
07:01It has a thick nitrogen atmosphere like Earth's
07:04and it's loaded with organic molecules,
07:07the same kinds of molecules
07:08that led to the origin of life on Earth.
07:11Dragonfly is going to be basically a nuclear powered drone
07:15that lands on Titan and samples the surface,
07:18examines those organic molecules
07:20to see if they're the kinds of molecules
07:22that may have led to life on Earth.
07:24And then it's going to take off
07:26and fly to different locations and repeat its experiments.
07:29So it's going to be the first time we've actually been able
07:31to explore a planet with an aerial craft
07:34that lands multiple places
07:36and does these kinds of experiments.
07:38We had a mission recently
07:40that went to an asteroid called Bennu
07:42and collected over a hundred grams of material
07:45from the surface of Bennu
07:47and brought it back to Earth.
07:49So we have in our labs now pieces of asteroid dirt.
07:52And what we found is that Bennu
07:54is full of the stuff of life, amino acids.
07:58Amino acids are the things, the building blocks
07:59that make up proteins and nucleotides,
08:02which are the components that make up DNA and RNA.
08:05So that's really exciting.
08:07It suggests that not just Earth,
08:09but all the planets were being sprinkled
08:11with the stuff that basically leads to an origin of life.
08:14So again, we haven't found life elsewhere,
08:17but we've been finding results
08:18that suggest that life should be common.
08:21At slash x slash text asks,
08:24Who came up with the flying saucer design
08:26and why did it stick?
08:27It turns out that flying saucers go back to a pilot
08:31named Ken Arnold, who was flying in the Pacific Northwest
08:34in 1947, and he reported something weird that he saw.
08:38What's interesting is that he never even said
08:40it was saucer shaped.
08:41He didn't understand, and he described its motion
08:44as skipping like a saucer.
08:46I think it's like when you skip rocks or something
08:48and it kind of bounces like that, that's what he apparently meant.
08:51And then it got reported in a newspaper
08:54as pilot sees mysterious flying saucer,
08:57and thus a huge trope was born.
09:02Pugbug2 from Reddit asks,
09:04How did the first life form on Earth emerge?
09:07We know something about the most primitive life forms on Earth
09:12because we study modern organisms and how they're all related.
09:16There's something called LUCA,
09:17the last universal common ancestor.
09:20Even though we don't have an example of it,
09:22by seeing how different life forms have evolved from it,
09:25we can reconstruct the properties of that last universal common ancestor.
09:29And so we know that it liked hot conditions.
09:33We know that it was a single celled organism.
09:35We have inferred that it occurred in a watery location.
09:38Some people think sea floor vents.
09:40Some people think tidal areas,
09:43those little ponds that were being wet and dried or freeze and thawed would have led to the right kinds of chemistry.
09:49We also have experiments that show that the building blocks of life are very easy to create.
09:55If you mix gases that were in the primitive atmosphere and you spark them with energy sources that were likely present lightning, ultraviolet light from the sun,
10:04you easily create these molecules like amino acids and other chemicals that clearly were important for the origin of life.
10:11You had gradual increases in chemical complexity.
10:15You probably had the formation of very simple membranes which separate inside from outside and allow the creation of cells.
10:22There are certain chemicals which you put them in water and they create membranes.
10:26We call them vesicles.
10:27We know the necessary chemistry.
10:29We know what some of the earliest life was like.
10:32We sort of were closing in on it from multiple directions.
10:35Next question.
10:36Wind Dancer Lore.
10:37WTF happened to Ceres.
10:40Ceres is a dwarf planet.
10:42It's basically one of the largest objects in the asteroid belt, but we call it a dwarf planet because it's large enough to be rounded by gravity.
10:50And recently we sent a spacecraft there and we found some surprising things.
10:55Most surprising you see this large crater in the center of this image.
10:59It's bright and white and what we found is that's a salt deposit.
11:03And that salt deposit indicates that there was water and it suggests that this was a water world at one point and may still even have liquid water on the inside.
11:13This is very exciting to astrobiologists because it means that dwarf planets like Ceres are places where you could have in the past had habitable conditions on the inside.
11:24And who knows, maybe at present some of these dwarf planets still have habitable oceans.
11:29So the more we explore the solar system, the more we're surprised by the level of activity on some of these worlds that we thought were dead.
11:37Newlanguage4727 asks, are there good scientific explanations for UFO sightings such as the USS Nimitz encounters in 2004?
11:47There are some intriguing reports and the USS Nimitz one is rather strange.
11:52You know, the ocean boiling some object that didn't look like a human made object seeming to fly at great speeds and so forth.
11:59I don't know how to explain it, but the bottom line is we see no reason to think this has anything to do with astrobiology or any kind of extraterrestrial technology.
12:09One of the videos that was recently popularized was taken by pilots.
12:13If you look at that video, it does look like something's moving sort of unnaturally fast.
12:17But it turns out if you analyze information we do have, a lot of that can be explained by parallax.
12:23That is the motion of the camera can make something look like it's moving much faster than it is.
12:29So people that have actually looked at the data have said, you know what, the speed isn't as great and the motion isn't as unnatural as we thought.
12:36But, you know, I'm the first to admit that there are things in our atmosphere that we don't understand.
12:40But as of now, I've not seen anything that tells me, aha, this is an extraterrestrial mystery.
12:46It's more like this is a plausible terrestrial mystery, but we don't know very much about it and we don't have very good documentation.
12:53Ashkir asks, what is the closest another habitable planet could be near Earth?
12:59It's probably roughly four light years.
13:02That is Proxima Centauri, which is in the nearest star system to Earth, which again, for perspective, the galaxy is about 100,000 light years.
13:11So four light years on the scale of the galaxy is very close.
13:15Of all the spacecraft we've launched, there are five of them that are on trajectories where they will actually escape our solar system.
13:22And most famously, Voyager 1 and Voyager 2 are on their way out and they will maybe encounter another star system in something like 100,000 years.
13:32But of course, it would be millions of years before one of them actually sort of wandered into the vicinity of a nearby star.
13:40Fellow on a mission asks, why is water essential for life on other planets?
13:45Everywhere on Earth where there's life, there's water.
13:47And almost everywhere on Earth where there's water, there's life.
13:51Water is sort of the universal solvent that allows life to happen.
13:54Basically, we are organic molecules dissolved in water, dancing together and doing complex things and reproducing themselves.
14:01As far as we can tell, that's what life is.
14:03You clearly need a liquid medium because the molecules have to come together in this complex 3D dance that if they're just frozen in a solid or loose in a gas, they won't do it.
14:14So as far as we can tell, you need a liquid for life.
14:16Water is a common liquid in the universe and has those properties of interacting with organics that we have not been able to mimic with any other chemical in a lab.
14:27So we don't know for sure that the universe couldn't have done it in some other way.
14:30Maybe we'll be surprised and find life in ammonia or methane or some other liquid.
14:34But as far as we can tell, water is the key to life in the universe.
14:39So Gabe 3115 asks, what do we think about assembly theory?
14:43So assembly theory attempts to describe the nature of life.
14:47What is the difference between living matter and non-living matter?
14:50How could we recognize that?
14:52Well, most of the universe is made of very simple molecules like this carbon dioxide.
14:57That's not a very complex molecule.
15:00But if you look at the molecules of life, like amino acids, you can see carbon, carbon, carbon, carbon bonded together in complex ways with other hydrogens.
15:08And they get much more complex than this.
15:10And they can be hundreds or thousands or tens of thousands of atoms bonded together.
15:15But you can see that this is very different from these simple molecules.
15:19And what assembly theory does is characterize the complexity of molecules in a way that tells us when something is complex enough so that it must have been made by life.
15:30One Skippy Dino asks, can someone give me a short explanation of the Drake equation and the probability of us being alone?
15:37I happen to have a copy right here.
15:39It's a way of thinking through the probability of extraterrestrial life that was devised by astronomer Frank Drake in the early 1960s.
15:46Frank Drake was the first one to actually point a radio telescope elsewhere from Earth and start to listen to see if he can find alien signals.
15:54And to help think through the probability of finding those signals, he came up with this really pretty simple equation.
16:00N is the number of communicating civilizations out there.
16:04R, that's just the rate of star formation in the galaxy.
16:08F sub P, the probability of planet formation around those stars.
16:13N sub E, the number of habitable planets per star.
16:17F sub L, the fraction of planets that have an origin of life.
16:21F sub I is getting into more speculative territory.
16:24That's the fraction of planets with life where intelligent life evolves.
16:29And of course we only have one example.
16:31It's Earth.
16:32And then F sub C is even more speculative.
16:35That's the fraction of planets with intelligent life that have communicating civilizations that are sending or possibly receiving messages.
16:42Finally multiplied by L, or the average longevity of communicating civilizations.
16:48If communicating civilizations don't last long, perhaps because they do themselves in through nuclear war or climate change or some other process,
16:57then the numbers suggest that civilizations that we could communicate with are probably very rare and might be hard to find out there.
17:05On the other hand, if L is long, because some civilizations can last very long time, they solve their problems, they learn how to live sustainably on a planet,
17:14then the math works out that there should be lots of civilizations out there that we can find.
17:19So the numbers vary widely depending on how you estimate some of these unknown factors.
17:23But some of these factors we do now know pretty well.
17:26We know the star formation rate in the galaxy, and importantly, we've recently discovered that planets are very, very common.
17:33That tells us that as long as the origin of life is not super, super rare, there must be lots and lots of planets out there with life.
17:42Chad from the future asks, why doesn't the Europa Clipper deploy something into the moon to check for life?
17:47At one point, there was the idea of including a lander on Europa Clipper, but it was decided that the real point of this mission is just to characterize Europa and decide if it is habitable.
17:59We'll then know which locations on the surface are the right locations to send a lander, whereas now we would sort of be guessing.
18:07But also, it costs a lot to send a mission to Europa, and the more complex you make the mission with an orbiter and a lander and other pieces, the price goes up and then you're less likely to have the mission at all.
18:18So if Clipper does confirm, as we suspect, that Europa is a habitable world, you can be sure that in the future we will be sending landers to directly search for life there.
18:29Browner555 asks, what is Area 51 actually used for?
18:34Well, I could tell you, but then I'd have to kill you.
18:37No, just kidding.
18:39Area 51 is a place where experimental military aircraft are tested.
18:45This is common knowledge, and that's all I know, and I've seen no evidence that it's anything else.
18:51Rinse the plates first asks, what is the Fermi paradox?
18:55So the Fermi paradox is named after the great Italian-American physicist Enrico Fermi, who famously asked, where is everybody?
19:03With all the possible life forms and civilizations in the galaxy, and with a galaxy that is billions of years old, why aren't there obvious signs of extraterrestrial life?
19:15That's really what we mean by the Fermi paradox.
19:18In my view, it's not really a paradox because we haven't really looked yet very thoroughly.
19:23With SETI, the Search for Extraterrestrial Intelligence, Jill Tartar, who's one of our great SETI scientists, has likened it to if the universe is an ocean, we've basically searched a teacup full of water.
19:36Even though we've been searching with radio telescopes for 60 years now, if you look at the number of stars we've looked at carefully and the frequencies we've analyzed, compared to the amount of search space there is, that it's just a teacup in the ocean.
19:50So we could have easily missed it.
19:52Infinity Scientist asks, what kind of technosignature could be detected from a very far away galaxy?
19:58That's an interesting one. If you were an alien looking at Earth, you might notice that our atmosphere has changed, you might notice lights from our civilization, those kinds of things we call technosignatures.
20:08Just any observation that can betray the existence of some kind of technological activity or civilization.
20:15The only kind of technosignature I can think of from a very far away galaxy would be some kind of incredibly advanced civilization that is actually manipulating the geometry of that galaxy in some way,
20:26creating things like Dyson spheres, these large structures in a solar system that are meant to gather all the solar energy from that star and power their technology.
20:36And that would put out an unusual infrared signature.
20:39So we actually have the ability to look for things like that.
20:42When we're talking about the possible abilities of very advanced technologies, you almost have to get very out there.
20:48Like Arthur C. Clarke said, any sufficiently advanced technology may be indistinguishable from magic.
20:54And the fact is, if you look at how fast technology changes, it's very hard to say it would be impossible for some civilization to create these astro-engineering works that would be visible from distant galaxies.
21:06Ulteriorkid324 asks, what is SETI? Is it just people listening to alien radio stations?
21:13So SETI stands for the Search for Extraterrestrial Intelligence.
21:16And it's been mostly radio searches, but more recently now we have what we call optical SETI, where the idea is that they may not be sending radio pulses.
21:25They may be sending laser pulses.
21:27So with optical SETI, we look in optical visible wavelengths for laser pulses from other stars.
21:33We also shouldn't confuse SETI with METI, which is messages to extraterrestrial intelligence, which is more controversial.
21:40Some people are opposed to METI for a couple of reasons.
21:43One is they think it's arrogant to assume that any one person or program or institution could speak for all of Earth.
21:50User 0301 asks, NASA announced it has detected a gas on a planet 120 light years away that might indicate life. How?
21:59So one of the things we do is we look for what we call biosignature gases in their atmospheres.
22:05A report was published that a chemical called dimethyl sulfide had been detected in the atmosphere of an exoplanet called K2 18b that might have a habitable, watery environment, which would be a very exciting thing to find.
22:19Dimethyl sulfide is a gas that on Earth is associated with life, largely, although there are other ways to make it.
22:25So they're not sure that dimethyl sulfide has really been found on this exoplanet.
22:31So as far as how we detect gases in a distant atmosphere of an exoplanet, we use spectroscopy.
22:37Basically, we observe the amount of light at a range of wavelengths across the visible, the infrared, the ultraviolet spectrum on an exoplanet.
22:45And we've learned that patterns in those spectra reveal the existence of different gases.
22:52So, for instance, this is a spectrum from an exoplanet called Wasp 96b.
22:57You can see some of these peaks and valleys.
22:59This is a peak that indicates water, which is pretty amazing because water is one of the key gases for thinking about life in the universe.
23:07Here's a question from the AskHistorians subreddit.
23:09Are there any compelling cases of UFO slash UAP sightings in history?
23:15From an astrobiology perspective, the short answer is no.
23:18There are a lot of phenomena in our atmosphere that have not been characterized yet.
23:22There have been things discovered recently.
23:24Strange high altitude lightning formations called sprites that were reported and dismissed and then they turn out to be real.
23:31I would not doubt that there are strange things in our atmosphere that have not yet been identified.
23:36Whether they are any indication of alien technology, to me that's a kind of last resort explanation.
23:42Even if they are technology, I would probably say it's much more likely that they are human technology that some humans know about and other humans don't.
23:50Why we have to resort to aliens to explain this to me, if anything, that seems kind of a lack of imagination or really a big leap that I wouldn't be prepared to make without some more specific evidence for that.
24:01At Redacted Media asks, what if we could see and interact with the shadow biome?
24:06What if there's some other form of life on Earth that we're not even fully aware of?
24:10What if there's another form of life perhaps hiding underground or in some place that we think is very uninhabitable because our kind of life couldn't exist there?
24:19You know, highly acidic places or places that are so extreme that we think life couldn't exist that in fact does exist on Earth.
24:25And that's the notion of a shadow biosphere.
24:27And by its very nature, the concept implies something we haven't really encountered or thought of yet.
24:32It's the kind of question that's worth our keeping in mind as astrobiologists so that we don't assume that we know everything about life when in fact we're just beginning to understand the possibilities for life in the universe.
24:45Here's another good question.
24:46Was there ever life on Mars?
24:48What I can tell you is the more we've studied Mars, the more we've learned about its earliest environment,
24:54it seems to be similar to the early environment of Earth at the time when the origin of life is believed to have happened.
25:01There are dried up river valleys.
25:03There are dried up lakes with waterborne sediments.
25:06There are flood valleys.
25:07All kinds of signs that Mars, when it was young, was a wet and warmer place with a more clement climate, with lakes, with flowing water, and most likely with organic molecules.
25:20So Mars, we believe, had the conditions for an origin of life.
25:24Have we found evidence for early life on Mars yet?
25:26No.
25:27But we're searching for it.
25:28And that's one of the reasons we have these Mars rovers, hopefully someday bringing samples back so that we can examine those rocks in our laboratories on Earth and identify for sure whether there was life on Mars.
25:40Pi1011 asks, would a Venus sample return mission be possible?
25:44It wouldn't be that easy because Venus has a very thick atmosphere.
25:48You can't see the surface because it's surrounded by these thick clouds of sulfuric acid, so battery acid.
25:54So it's not an easy place to explore or to get to.
25:58Ultimately, we would really like to do so.
26:00Having samples on Earth is so valuable because instead of having to send your little instruments up there and do the experiments and radio home the results,
26:07you can have a whole Earth laboratory.
26:09You can have all the time that you want using all the resources of our laboratory.
26:14Pokoro asks, is a habitable planet with no tectonic activity plausible?
26:19We're still trying to understand the nature of habitability.
26:22But one thing that's certainly true about Earth, the one habitable planet we know, is that possibility for life here is facilitated by plate tectonics,
26:31by the motion of the Earth's surface driven by the motion of the interior, which moves the surface around and not only makes mountains and earthquakes and all that,
26:40but brings nutrients continually to the surface and sort of renews the surface of the Earth, keeps it fertile.
26:46We definitely think tectonic activity is related to habitability.
26:50And you would imagine for a planet to be habitable, there needs to be some kind of ongoing geological activity.
26:56Is it absolutely required? We don't know.
26:58For instance, there are these ocean worlds like Europa and other places where habitability could just be on the inside.
27:05And maybe you would not have tectonic activity in the outside if there were other energy sources and way of recycling nutrients.
27:11CoochieMan127 asks, do you think we detect intelligent life within the next 100 years?
27:18So with the James Webb Space Telescope, we're just getting to the point where we can identify gases in exoplanet atmospheres.
27:24And with future space telescopes, then we will have the ability to really say what's in that atmosphere of this exoplanet and that exoplanet.
27:33And once we can do that, then we at least have a chance of finding some kind of technosignature.
27:39Similarly, our radio searches are getting much more sophisticated.
27:43So the completeness with which we're examining the rest of the universe is increasing rapidly,
27:48which makes me think, again, if the aliens are there waiting to be found,
27:52that within the next 100 years we have a pretty decent chance of finding them.
27:55So those are all the questions for today, and thanks for watching. Alien Support.
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