Astrobiologist Answers Astrobiology Questions

What is Area 51 actually used for?

Well, I could tell you, but then I'd have to kill you.

No, [laughs] just kidding.

I'm Astrobiologist David Grinspoon from NASA.

Let's answer your questions from the internet.

This is Alien Support.

[energetic music]

Disgruntled Hermit asks,

What's the most interesting exoplanet you've read about?

If I had to pick a favorite that we found so far,

it would be the planets in the TRAPPIST-1 system.

There are seven planets in the system that we've identified

so far, and probably about three

of them are potentially habitable.

And by the way, the TRAPPIST system is

only 40 light-years away.

Which, if you consider that our galaxy is

a 100,000 light-years across, that's relatively close.

I have a sort of chart here,

and you can see the habitable zone of the TRAPPIST system

with several potential planets in it, compared

to the habitable zone of our solar system on the bottom,

which has Earth, and then you know, sort of possibly Venus

and Mars on the edges of habitability.

And by the way, the TRAPPIST system here,

it's a cooler star than our sun.

It's a red dwarf, and so the planets are

clustered very close.

But imagine what it would be like

for life evolving on a system

with multiple habitable planets

nearby one another.

Meteorites occasionally get blasted off

of one planet and land on another.

We have pieces of Mars here on Earth.

So, if you have a habitable planet with life

and another planet that could be habitable,

you could imagine life spreading easily.

Jabalandkie asks, Are aliens real?

Well, my thought is that aliens are real.

There are probably something

like 30 billion habitable planets in our own galaxy.

And so, even if a small fraction of those have an origin

of life, there's lots of life in our galaxy.

And the more we study Earth

and its origins, we haven't found anything that's sort

of magical or so special about Earth

that those things shouldn't be happening elsewhere.

So if you're asking me, do I think aliens are real, yes.

If you're asking me, do I know scientifically,

I'll say not yet, but we're on the road to find out.

Here's a question from Quora.

How accurate is 'Arrival' scientifically?

I really like the movie Arrival.

I'm watching this scene here

with this astrobiologist, glossed in wonder and awe,

and a little bit of terror, encountering this alien.

We talk about convergent evolution.

That evolution on other worlds would find some

of the same solutions.

So the idea that they have something that's like fingers

for grasping, that makes sense.

The idea that they would have this kind

of symmetry just like we have bilateral symmetry,

they look vaguely squid-like, vaguely octopi,

like I wouldn't be surprised if we saw complex aliens

if they looked somewhat familiar,

but not exactly like any organism we had seen before.

Because again, they'll be responding

to the same overall kinds of evolutionary forces.

And then you have the other factor where she's trying

to communicate, and this alien is doing this weird kind

of circular writing,

and it turns out that they are trying to communicate with us

and they're as equally puzzled by us.

That makes sense because I think there's this whole idea,

something called incommensurability,

that it might really be hard to communicate

'cause they might have very different kinds of cognition,

very different notions of reality and time.

So I find this alien very convincing.

Utopia Circle asks, How exoplanets are discovered?

You can't directly observe the planet

because they're too dim and too far away,

but you can notice what the planet is doing to the star.

So, as a planet orbits a star,

because of the gravitational pull of that planet,

the star actually wobbles a little bit.

So that star is wobbling

'cause there's a planet around it,

even though you can't see the planet.

So, some of the time, the star is coming

towards your telescope, and some

of the time, the star is coming away from your telescope.

We call that a Doppler shift.

When it's coming towards you, the frequency shifts

to a higher frequency, blue.

When it's coming away from you, it shifts

to a lower frequency red.

And so, our instruments got good enough to detect

that slight change, that rhythmic change from blue

to red to blue to red.

It's a very, very tiny shift in wavelengths.

And that was the first sign.

And then, later on, there was a new technique

that's called the transit method.

When a planet passes directly in between you

and the star, you can notice that little bit

of dimming of starlight.

It's very tiny 'cause planets are small

compared to the star.

But if you have a very sensitive measurement of the light

of that star over time, when a planet passes just in front

of it, the star will dim a little bit.

And so, if you watch the light curve over time of that star,

it'll wobble up and down and up and down and up and down.

So you're not so much seeing the planet as noticing

that the planet is blocking the star a little bit,

causing it to periodically dim.

It only works when the geometry's right,

if it's a little bit above or a little bit below,

the direct line between your telescope

and that star, you'll miss it.

So only about 5%

of stars have planets oriented in the right plane,

the right direction to use that transit method.

But when things are lined up right, it's very sensitive.

So that has allowed us now,

especially with space telescopes,

like there was an instrument called Kepler that was designed

to use the transit method to find lots of exoplanets.

And that was really what revealed to us

that most stars in the Universe have planets.

Sowhatvirgo asks, Where do astrobiologists work?

How hard is it to get a job in astrobiology?

So astrobiologists work a lot at universities.

Some of them work in government labs.

Some of us build spacecraft

and send them out to observe other planets.

Some of us do field work

and study exotic locations, go on expeditions

where there's extreme life to understand the limits of life,

and look for some of the earliest signs of life.

This is a rock called a stromatolite.

This one comes from Western Australia

and is about 2.7 billion years old.

And if you look in close, you see this rock is made up

of layers, and what we've learned is

that those layers are from ancient microbial mats.

Some of the earliest life on Earth

that formed these layers on,

what was then the C4 microbes, single-celled organisms,

using the energy of sunlight, using different kinds

of nutrients flowing in the seawater,

and organizing themselves into these layers.

Im at your moms house, asks, What is taking NASA so long

to find them aliens?

What active missions are they doing?

Well, it's a big Universe out there,

but we're working on it.

Obviously, we have rovers on Mars searching

for the signs of ancient life.

So, we have a mission now on its way to Europa, a Moon

of Jupiter that is home to a vast ocean of liquid water.

So, we have a mission called Europa Clipper orbiting

the Jupiter system and making close passes

by Europa in the early 2030s, helping us to understand

if that ocean is habitable, what's the temperature,

the pressure, what are the flows of nutrients, and so forth.

Is that ocean a place that could support life?

And if it is, that would motivate us

to send missions in the future

that would land on the surface,

and maybe even tunnel under the ice in submarines

to look directly for life on Europa.

We also have a mission called Dragonfly

that's going to launch in a few years and go to Titan.

Titan is a moon of Saturn.

It has a thick nitrogen atmosphere like Earth's,

and it's goaded with organic molecules, the same kinds

of molecules that led to the origin of life on Earth.

Dragonfly is going to be basically a nuclear-powered drone

that lands on Titan,

and samples the surface, examines those organic molecules

to see if they're the kinds of molecules that may have led

to life on Earth, and then it's going to take off

and fly to different locations and repeat its experiments.

So, it's gonna be the first time we've actually been able

to explore a planet with an aerial craft

that lands multiple places

and does these kinds of experiments.

We had a mission recently that went

to an asteroid called Bennu.

It collected over 100 grams

of material from the surface of Bennu,

and brought it back to Earth.

So we have, in our labs now, pieces of asteroid dirt,

and what we found is that Bennu is full of the stuff

of life, amino acids.

Amino acids are the things, the building blocks

that make up proteins.

And nucleotides, which are the components

that make up DNA and RNA.

So that's really exciting.

It suggests that not just Earth,

but all the planets, were being sprinkled with the stuff

that basically leads to an origin of life.

So, again, we haven't found life elsewhere,

but we've been finding results that suggest

that life should be common.

X/x/.txt asks, Who came up

with the flying saucer design, and why did it stick?

It turns out that flying saucers go back

to a pilot named Ken Arnold,

who was flying in the Pacific Northwest in 1947,

and he reported something weird that he saw.

What's interesting is

that he never even said it was saucer-shaped.

He didn't understand,

and he described its motion as skipping like a saucer.

I think it's like when you skip rocks or something,

and it kind of bounces like that.

That's what he apparently meant.

And then it got reported in a newspaper

as Pilot sees mysterious flying saucer.

And thus, a huge trope was born.

PUGBUG2 from Reddit asks,

How did the first life form on Earth emerge?

We know something about the most primitive life forms

on Earth because we study modern organisms

and how they're all related.

There's something called LUCA,

the Last Universal Common Ancestor.

Even though we don't have an example of it,

by seeing how different life forms have evolved from it,

we can reconstruct the properties

of that Last Universal Common Ancestor.

And so, we know that it liked hot conditions.

We know that it was a single-celled organism.

We have inferred that it occurred in a watery location.

Some people think sea floor vents.

Some people think tidal areas, little ponds

that were being wet and dried or freeze,

and thawed would've led to the right kinds of chemistry.

We also have experiments that show that the building blocks

of life are very easy to create.

If you mix gases that were in the primitive atmosphere,

then you spark them with energy sources

that were likely present,

lightning, ultraviolet light from the sun.

You easily create these molecules like amino acids

and other chemicals that clearly were important

for the origin of life.

You had gradual increases in chemical complexity.

You probably had the formation

of very simple membranes which separate inside from outside,

and allow the creation of cells.

There are certain chemicals which you put 'em in water

and they create membranes.

We call 'em vesicles.

We know the necessary chemistry, we know what some

of the earliest life was like.

We sort of were closing in on it from multiple directions.

Next question. WinddancerLor.

WTF happened to Ceres?

Ceres is a dwarf planet.

It'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.

And recently, we sent a spacecraft there,

and we found some surprising things.

Most surprising, you see this large crater

in the center of this image.

It's bright and white,

and what we found is that's a salt deposit.

And 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.

This 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.

And who knows, maybe at present, some

of these dwarf planets still have habitable oceans.

So 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.

New Language4727 asks,

Are there good scientific explanations

for UFO sightings,

such as the USS Nimitz encounters in 2004?

There are some intriguing reports,

and the USS Nimitz one is rather strange.

You know, the ocean boiling some object

that didn't look like a human-made object,

seeming to fly at great speeds, and so forth.

I don't know how to explain it, but the bottom line is,

and we see no reason to think this has anything to do

with astrobiology, or any kind

of extraterrestrial technology.

One of the videos that was recently popularized was taken

by pilots.

If you look at that video,

it does look like something's moving,

sort of, unnaturally fast.

But it turns out if you analyze information we do have,

a lot of that can be explained by parallax.

That is the motion

of the camera can make something look like it's moving

much faster than it is.

So, people that have actually looked at the data said,

You know what, the speed isn't as great,

and the motion isn't as unnatural as we thought.

But you know, I'm the first to admit

that there are things in our atmosphere

that we don't understand.

But as of now, I've not seen anything that tells me, aha,

this is an extraterrestrial mystery.

It'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.

Ashkir asks, What is

the closest another habitable planet could be near Earth?

It's probably, roughly, four light-years,

that is Proxima Centauri,

which is in the nearest star system to Earth,

which, again, for perspective,

the galaxy is about 100,000 light-years.

So, four light-years on the scale

of the galaxy is very close.

Of all the spacecraft we've launched, there are five of them

that are on trajectories

where they will actually escape our solar system.

And 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.

But, of course, it would be millions of years

before one of them actually sort

of wandered into the vicinity of a nearby star.

Fellaonamission asks, Why is water essential

for life on other planets?

Everywhere on Earth where there's life, there's water.

And almost everywhere on Earth where there's water,

there's life.

Water is sort of the universal solvent

that allows life to happen.

Basically, we are organic molecules dissolved in water,

dancing together and doing complex things,

and reproducing themselves.

As far as we can tell, that's what life is.

You 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.

So, as far as we can tell, you need a liquid for life.

Water 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.

So we don't know for sure

that the Universe couldn't have done it in some other way.

Maybe we'll be surprised and find life in ammonia

or methane, or some other liquid.

But as far as we can tell, water is the key

to life in the Universe.

So, Gabe3115 asks,

What do we think about assembly theory?

So, assembly theory attempts to describe the nature of life.

What is the difference between living matter

and non-living matter?

How could we recognize that?

Well, most of the Universe is made

of very simple molecules like this carbon dioxide.

That's not a very complex molecule.

But 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.

And they get much more complex than this,

and they can be hundreds or thousands

or tens of thousands of atoms bonded together.

But you can see

that this is very different from these simple molecules.

And 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.

Oneskipydino asks,

Can someone give me a short explanation

of the Drake equation, and the probability

of us being alone?

I happen to have a copy right here.

It's a way of thinking through the probability

of extraterrestrial life that was devised

by Astronomer Frank Drake in the early 1960s.

Frank 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.

And to help think through the probability

of finding those signals,

he came up with this really pretty simple equation.

N is the number of communicating civilizations out there.

R, that's just the rate of star formation in the galaxy.

F-sub-P, the probability of planet formation

around those stars.

N-sub-e, the number of habitable planets per star.

F-sub-l, the fraction of planets

that have an origin of life.

F-sub-i is getting into more speculative territory.

That's the fraction of planets with life

where intelligent life evolves.

And of course, we only have one example, it's Earth.

And then f-sub-c is even more speculative.

That's the fraction of planets with intelligent life

that have communicating civilizations that are sending

or possibly receiving messages.

Finally, multiplied by L or the average longevity

of communicating civilizations.

If communicating civilizations don't last long,

perhaps because they do themselves in through nuclear war

or climate change or some other process,

then the numbers suggest

that civilizations that we could communicate with are

probably very rare and might be hard to find out there.

On the other hand, if L is long,

because some civilizations can last a very long time,

they solve their problems, they learn how

to live sustainably on a planet, then the math works out

that there should be lots of civilizations out there

that we can find.

So the numbers vary widely depending

on how you estimate some of these unknown factors.

But some of these factors we do now know pretty well.

We know the star formation rate in the galaxy.

And importantly, we've recently discovered

that planets are very, very common.

That 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.

Chadfromthefuture asked, Why doesn't

the Europa Clipper deploy something into the moon

to check for life?

At 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.

We'll then know which locations on the surface are

the right locations to send a lander.

Whereas now, we would sort of be guessing it.

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.

So, 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.

Browner555 asks, What is Area 51 actually used for?

Well, I could tell you, but then I'd have to kill you.

No. [laughs] Just kidding.

Area 51 is a place

where experimental military aircraft are tested.

This is common knowledge, and that's all I know,

and I've seen no evidence that it's anything else.

Rinsetheplates_first asks, What is the Fermi Paradox?

So the Fermi paradox is named

after the great Italian American physicist Enrico Fermi,

who famously asked, Where is everybody?

With 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?

That's really what we mean by the Fermi Paradox.

In my view, it's not really a paradox

'cause we haven't really looked yet, very thoroughly.

With SETI, the Search for Extraterrestrial Intelligence,

Jill Tarter, 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.

Even 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.

So we could have easily missed it.

InfinityScientist asks, What kind

of techno signature could be detected

from a very faraway galaxy?

That'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 techno signatures.

Just any observation that can betray the existence

of some kind of technological activity or civilization.

The only kind of techno signature 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.

Creating 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.

And that would put out an unusual infrared signature.

So, we actually have the ability to look

for things like that.

When we're talking about the possible abilities

of very advanced technologies,

you almost have to get very out there.

Like Arthur C Clarke said,

Any sufficiently advanced technology may be

indistinguishable from magic.

And 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 astroengineering works

that would be visible from distant galaxies.

Ulteriorkid324 asks, What is SETI?

Is it just people listening to alien radio stations?

So, SETI stands for

the Search for Extraterrestrial Intelligence,

and 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,

they may be sending laser pulses.

So with optical SETI, we look in optical visible wavelengths

for laser pulses from other stars.

We also shouldn't confuse SETI with METI,

which is Messages to Extraterrestrial Intelligence,

which is more controversial.

Some people are opposed to METI for a couple of reasons.

One is they think it's arrogant to assume

that any one person or program

or institution could speak for all of Earth.

User0301 asks,

NASA announced it has detected a gas

on a planet 120 light-years away

that might indicate life, how?

So, one of the things we do is we look for

what we call bio signature gases in their atmospheres.

A 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.

Dimethyl sulfide is a gas that, on Earth,

is associated with life largely,

although there are other ways to make it.

So they're not sure that dimethyl sulfide has

really been found on this exoplanet.

So, as far as how we detect gases in a distant atmosphere

of an exoplanet, we use spectroscopy.

Basically, we observe the amount of light at a range

of wavelengths across the visible, the infrared,

the ultraviolet spectrum on an exoplanet.

And we've learned

that patterns in those spectra reveal

the existence of different gases.

So, for instance, this is a spectrum

from an exoplanet called WASP-96 b.

You can see some of these peaks and valleys.

This 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.

Here's a question from the AskHistorians Subreddit.

Are there any compelling cases

of UFO/UAP sightings in history?

From an astrobiology perspective,

the short answer is no.

There are a lot of phenomena in our atmosphere

that have not been characterized yet.

There have been things discovered recently,

strange high altitude, lightning formations called sprites

that were reported and dismissed,

and then they turn out to be real.

I would not doubt

that there are strange things in our atmosphere

that have not yet been identified,

whether they are any indication of alien technology,

to me, that's a kind of last resort explanation.

Even 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.

Why 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.

@Redacted Media asks, What if we could see

and interact with the shadow biome?

What if there's some other form of life on Earth

that we're not even fully aware of?

What 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?

You know, highly acidic places

or places that are so extreme

that we think life couldn't exist.

That, in fact, does exist on Earth.

And that's the notion of a shadow biosphere.

And by its very nature,

the concept implies something we haven't

really encountered or thought of yet.

It's a 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.

Well, here's another good question.

Was there ever life on Mars?

What I can tell you is the more we've studied Mars,

the more we've learned about its earliest environment.

It seems to be similar to the early environment

of Earth at the time when the origin

of life is believed to have happened.

There are dried-up river valleys, there are dried-up lakes

with waterborne sediments, there are flood valleys,

all 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.

So, Mars, we believe, had the conditions

for an origin of life.

Have we found evidence for early life on Mars yet?

No, but we're searching for it.

And that's one of the reasons we have these Mars rovers,

and 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.

Pietin11 asks,

Would a Venus sample return mission be possible?

It wouldn't be that easy

because Venus has a very thick atmosphere.

You can't see the surface

because it's surrounded by these thick clouds

of sulfuric acids, so battery acid.

So it's not an easy place to explore or to get to.

Ultimately, we would really like to do so.

Having 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,

you can have a whole Earth laboratory.

You can have all the time that you want,

and using all the resources of our laboratory.

Pokoirl asks, Is a habitable planet

with no tectonic activity plausible?

We're still trying to understand the nature

of habitability, but 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,

by 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,

but brings nutrients continually to the surface,

and sort of renews the surface of the Earth.

Keeps it fertile.

We definitely think tectonic activity is related

to habitability.

And you would imagine for a planet to be habitable,

there needs to be some kind of ongoing geological activity.

Is it absolutely required?

We don't know.

For instance, there are these ocean worlds like Europa

and other places where habitability could just be

on the inside,

and maybe you would not have tectonic activity

in the outside if there were other energy sources

and way of recycling nutrients.

Coochieman127 asked,

Do you think we detect intelligent life

within the next 100 years?

So, with the James Webb Space Telescope, we're just getting

to the point where we can identify gases

in exoplanet atmospheres, and with future space telescopes,

then we will have the ability to really say

what's in that atmosphere

of this exoplanet and that exoplanet.

And once we can do that, then we at least have a chance

of funding some kind of techno signature.

Similarly, our radio searches are getting

much more sophisticated.

So, the completeness with which we're examining the rest

of the Universe is increasing rapidly, which makes me think,

again, if the aliens are there waiting to be found,

that within the next 100 years,

we have a pretty decent chance of finding them.

So those are all the questions for today.

And thanks for watching Alien Support.

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