Could we seed exoplanets with life?

Daniel and Kelly wrangle with the tricky science and ethics of sending microbes to distant worlds.

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Episode Transcript

Speaker 1 (00:08):
Hey, Kelly, I have an unusual aliens question for you.

Speaker 2 (00:11):
It is never good for me when a question starts
like that. It's I have an unusual aliens question for you?
Or what is in my poop? As a parasitologist, I
get a lot of that, So go on, I can't wait.
Where are you going with this?

Speaker 1 (00:25):
All right? So, as a parasitologist, do you ever see
a critter infected with something new? And wonder?

Speaker 2 (00:31):
Hmm?

Speaker 1 (00:32):
Is this an alien parasite?

Speaker 3 (00:34):
No?

Speaker 2 (00:34):
Never, There's so many weird things on Earth. I don't
feel like we need to go to space to explain them.
And the other day I saw someone trying to make
the argument, like in an actual like sciencey pop magazine,
that octopus like octopodes, Oh gosh, let's not get into
how you pluralize that might be aliens. And I'm like,
oh my gosh, dude, their genome fits nicely in the

(00:56):
tree of life. This isn't complicated. So the answer is no.

Speaker 1 (01:00):
All right, But then my question is how exactly can
you tell? I mean, do you think like if alien
parasites did come to Earth, could they do their parasiting
on us? Would they find us tasty or be like
incompatible with us.

Speaker 2 (01:11):
So that's an interesting question. You know, it might be
that they wouldn't be able to eat us, or that
they wouldn't be able to like, you know, bind to
whatever receptors inside of us they needed to. But you know,
for as far as how far or what do you
need to do to tell? You know, you could like
take a DNA sample and you know, see if they
fit on the tree of life or not. But yeah,

(01:31):
I don't know hard to know, so I guess I'd
say it's impossible to know. But I'm guessing that we
do look different from the kind of things that aliens
are used to sucking on out in space.

Speaker 1 (01:42):
I'm going to take it as a compliment that aliens
don't want to suck on any parts of me.

Speaker 2 (01:46):
You know, That's exactly how I meant it.

Speaker 1 (01:48):
Did Hi, I'm Daniel, I'm a particle physicist, and I'm
doing my best to be not attractive to alien parasites.

Speaker 2 (02:10):
I'm Kelly Widersmith, and you probably don't have any alien parasites.
But if you do, send them to me, because I'd
love to see them.

Speaker 1 (02:18):
How are we going to find out? Kelly? Are you
planning to chop me up to see.

Speaker 2 (02:21):
Sure, yeah, better you than my kids.

Speaker 1 (02:26):
You didn't take very long to think about that. You
went right into Yes, I'm gonna chop up my co host.

Speaker 2 (02:31):
Some questions are easy to answer.

Speaker 1 (02:35):
And welcome to the podcast Daniel and or He Explain
the Universe, a production of iHeartMedia where we tackle all questions,
those that are easy to answer and those that are
harder to answer. Questions about the deep nature of the universe,
questions about what's out there, questions about how it all works,
and questions about who else might be out there in

(02:56):
the universe. Orge can't be with us today, but I'm
very please to have Kelly here to talk to us
about aliens landing on Earth and potentially sending our parasites
out to alien planets.

Speaker 2 (03:06):
Oh is this the world needs more parasites. I'm so excited.
The universe needs more parasites, not just the world share them?
No know, is that a weird take? I don't.

Speaker 1 (03:18):
I'll admit I have a hard time getting warm and
fuzzies for parasites. I always think of those wasps that
like lay their eggs inside spiders and then control them
until they die, driving them around like some horrific bumper car. Like,
oh man, that is just not a warm and fuzzy
oh I.

Speaker 2 (03:33):
Love watching videos of that. It's it's so creepy and
like usually, so I have to admit, even though I'm
a biologist, and I might take my biologist card away
for saying this, I find spiders a little creepy. I
said it, but I almost feel bad for them when
I see them getting parasitized and like manipulating their web
building behavior and then the babies like stick a straw

(03:54):
in the back of the spiders and and it's it's
kind of creepy. I feel bad for spiders sometimes they
have my sympathy.

Speaker 1 (04:02):
And you know, if we could have those wasps on
the podcast and we would ask them, like, how do
you feel about zombifying those spiders, they would answer with
the same cold, calculating quickness that you answered when you
said you would chop me up on the podcast. There
would be like, no problem, let's do it.

Speaker 2 (04:16):
Yeah. Well, so, fortunately for me, I am a low
on introspection ability, so I'm not going to think too
hard about what that says about me. But I am
super glad that I am not the kind of organism
that wasps can manipulate life. Is good being a human,
or at least being a human in North America.

Speaker 1 (04:33):
Until those alien wasps land here on Earth. And it's
a regular trope in science fiction that if you go
out into space you might catch some sort of weird
alien virus which takes over and infects the entire biome,
polluting the Earth and demolishing life on Earth. Or if
we land on Mars, we could accidentally pollute Mars with
some sort of Earth based microbe. This question of keeping

(04:56):
things sterile, of keeping things separate is a standard issue
in science fic and also in real life space missions.

Speaker 2 (05:03):
Yeah, we go to great lengths to try to make
sure we don't do what's called forward contamination getting Earth
microbes out on Mars. And then we were very careful
to make sure that, you know, when the astronauts came
back from the Moon, there was no backwards contamination. They
didn't bring any microbes back from the Moon. And so
far I think we've had pretty good success. But if
I had to bet, I would bet some of our
extremophiles have made it to Mars. Do you know Daniel

(05:25):
has anybody? Uh, surely someone's looked.

Speaker 1 (05:27):
At that I know that there are Tarte grades that
crash landed on the Moon in that Israeli experiment gone bad,
and they're probably busy building a colony up there and
planning to return with weapons. Yeah, that's pure speculation, of course. Yeah,
I feel like I have to say that, since this
is supposed to be a heavy science podcast, anytime we
say something silly, I want to make sure people know

(05:48):
when we're joking. But in terms of sending things to Mars,
you know, we have sent stuff from here to Mars,
and we have done our best to cleanse it of microbe.
But my wife is a microbiologist, and she always tells
me it's essentially impossible to remove microbes. I mean, you
will find microbes in every environment on Earth because there's

(06:10):
always some little critter capable of eating whatever poison you're
using to cleanse it of microbes. So I'd be very
skeptical that our landers have no microbes on them. So,
since I happen to be married to a microbiologist, I
thought it'd be fun to ask Katrina about it directly,
and so I did. So. Welcome to the podcast, Katrina,
Thanks very much for joining us.

Speaker 3 (06:30):
Thanks for having me and thanks.

Speaker 1 (06:32):
For contributing your biochemical expertise. Oh boy, So my first
question is what are the chances that we have already
polluted Mars and the Moon with microbes from Earth?

Speaker 4 (06:43):
What a great question, and you know there are teams
of people who are devoting their life work to figuring
this out.

Speaker 3 (06:48):
So you know you're asking me as a bystander to
answer that question.

Speaker 4 (06:51):
But there have been some fascinating experiments where people, for example,
have found that up at JPL in Pasadena, California, they
use these really stringent cleaning reagents to try to remove
all the microbes from the surface of the spacecraft, and
they find that there are microbes that can actually eat
the most difficult cleaning reagent. You can imagine, it's like

(07:12):
bleach yum carbon source. They'll eat that. So what are
the chances that one of those microbes that survived JPL's
most atrocious molecules they could think of to kill all
the microbes and then also survived getting out of the
atmosphere of Earth and the transport to Mars. What do
I think the chances are? I think it's possible. Yeah,

(07:34):
I'm not saying these are like happy dividing cells.

Speaker 3 (07:38):
Of microbes.

Speaker 4 (07:38):
It's just that microbes have first of all, the most
diverse strategies you could imagine, so there's every time you
got an idea, they've got a million more. And then
they can form these very dormant sporelike or spore particles
that basically you know, squirrel away and hide their DNA inside.

Speaker 3 (07:58):
Of like many, many many layers of protection.

Speaker 4 (08:01):
So I think it's very possible that something in that
type of form. Ironically, the attempts to clean the spacecraft
could actually select for microbes that are really extra tough,
and therefore they would have a better chance of having
made it to Mars. Now, I'm not saying that when
they get to Mars then they're going to be like
stretching out, jumping in the pool, having a great life.

(08:22):
I mean, they're still going to be stuck in their
dormant state. But is it possible that if you like
brought some water to Mars and then it could like
wake those bugs up, you know, that kind of thing
could happen.

Speaker 2 (08:33):
Yeah, But so I guess the second question is if
it can, so, it would need to survive the chemicals
the vacuum of space, and then find something to eat.
On Mars, and that's a lot of hoops to jump through.
You'd need a lot of variability in the microbes that
make it to Mars. But you know, if Jurassic Park
taught me anything it's that life finds a way.

Speaker 1 (08:55):
Exactly. Katrina is always telling me. Like you pick up
a scoop of like boiling acidic water near some vent,
you'll find like ten to the nine bacteria in every
cubic centimeter. Or if you look at some satellite we're
sending up into space, you'll find microbes on the outside
that eat the bleach they were using to kill the microbes.
But you're right, those microbes have survived that environment. That
doesn't guarantee that they're going to be able to survive

(09:16):
any arbitrary environment. These extremo files are evolved to live
in their particular niches.

Speaker 2 (09:22):
So should we stop trying?

Speaker 1 (09:23):
I think we should just give up on the whole
field of biochemistry. I mean, that's what that's what I think.

Speaker 2 (09:29):
That's how I felt when I was in college.

Speaker 1 (09:31):
No, I think it is important that we try to
separate these things. I mean, imagine we land on Mars
and we discover microbes there. We want to know, are
these Earth microbes or not? And even if they have
Earth like DNA, we want to know did these come
from Earth or maybe all of life on Earth came
from microbes on Mars that were blasted off the surface.

(09:52):
That's an actually legitimate, non joking scientific theory about the
potential origin of life on Earth. So we want to
know if we've infected life on Mars.

Speaker 2 (10:01):
So I know that we have bits of like Mars
that have been blown out into space and I think
they've landed, and like being able to find them in Antarctica.
Have we looked for alien microbes in those and found
anything yet?

Speaker 1 (10:13):
Oh, we definitely have looked for alien microbes, And a
few decades ago there were scientists who were confident they
had found them. They saw these little microtubules, and even
President Clinton made this huge announcement, like on the lawn
of the White House, that we thought we had found
life on Mars. These days, though, we have other non
life based explanations for those formations, so people are pretty
convinced that's not evidence for life on Mars. But you know,

(10:36):
we've gotten like a few rocks from Mars that we
could study here on Earth, And so it's a pretty
small sample. We're hoping in the next decade or so
to do Mars sample return. Would they pick up rocks
from the surface of Mars and send them back here
to Earth via some ridiculously complicated Rube Goldberg set of devices.
But we're all excited to study those and maybe define
microbes there that would be exciting.

Speaker 2 (10:58):
I hope we can contain them and they don't take
over our minds.

Speaker 1 (11:02):
But we can also think beyond our Solar system and
wonder what about microbes on planets around other stars? Do
we need to take the same sort of considerations about
avoiding polluting exoplanets or maybe we should turn the question
on its head and on purpose pollute those exoplanets with
our kind of life.

Speaker 2 (11:19):
You know. I feel like maybe we shouldn't have two
scientists talking about this, we should have like a philosopher
slash ethicist. But we've got what we've got, So what's up.
We don't have anybody with an ethical compass here, so
let's plow forward with this question.

Speaker 1 (11:34):
But fortunately we do. We got a question from a listener, Haley,
who is nine years old, and she's young enough to
have sort of like an intuitive philosopher's heart and sense
of ethics at least, And so she wrote in with
this question him.

Speaker 5 (11:47):
My name is Haley, I'm nine years old and today's
my birthday. I was actually wondering, if human wanted to
live after ours was gone, can't you put like micros
and back to on a different planet and let them
evolve there? And I was wondering, do you think astronauts

(12:11):
accidentally bring little small form like life forms to out
of Earth and put them somewhere else, like on their
clothes or the rockets by accident?

Speaker 2 (12:24):
Thanks Hailey, those questions are so great and happy belated birthday, And.

Speaker 1 (12:32):
How sad is it that we have to rely on
nine year olds to be our ethical compass.

Speaker 2 (12:36):
Yeah? No, I think when my kids grow up, it's
gonna be uh, it's gonna be everyone for themselves here.

Speaker 1 (12:41):
So I thought this was a really fun question, and
I started looking into it, and I discovered that there's
a whole project, a whole group of people with specific
plans and ideas to do just this, to send our microups,
our bacteria two different planets around other stars and to
see them with life, And is.

Speaker 2 (13:00):
The goal so that you can make those habitats more
hospitable if humans ever decide they want to move there
or are they just doing it like as a fun
you know, and end equals too for like the possible
pass evolution could take.

Speaker 1 (13:16):
You're asking me if they're being responsible or if they're
just like mucking around out of curiosity.

Speaker 2 (13:20):
No, they're pretty clearly mucking around. But I want to
know how they justify the exercise.

Speaker 1 (13:26):
Well, that's exactly what we're gonna be talking about today
as we answer the question could we seed exoplanets with
basic life?

Speaker 2 (13:40):
Well, we should see what the listeners have to say.

Speaker 1 (13:42):
Thank you very much to our group of listeners who
answer these random and sometimes weird questions. We love hearing
what you have to say and hearing your voice on
the podcast. If you'd like to be part of this
not very select group of lead volunteers, please write to
me to Questions at Danielandjorge dot com. Everybody is welcome.
Think about it for a minute. Do you think we
could seed exoplanets with basic life? Here's what people had

(14:06):
to say.

Speaker 6 (14:07):
I reckon we could seed life on an exoplanet if
if the environment was suitably similar to Earth and there
was some kind of energy source for the life to
capitalize on. I imagine it would require a little bit
of engineering of the life unless we got very, very
lucky with the environment.

Speaker 1 (14:19):
I believe it may be possible to see exoplanets with life. However,
I don't think we're anywhere near that capability. Were probably
many centuries of that millennia away from that.

Speaker 7 (14:29):
I think that if an exoplanet has no existing life,
then seeding life should be possible. But if there's anything
there already, then the differences in proteins and whatever else
it may have developed there would mean that it would
be pretty unlikely without wiping out whatever was.

Speaker 8 (14:45):
Their first I think we could, although precisely sending a
rocket to an exoplanet would be really tricky. But should
we Maybe while trying to seed life, we may end
up disrupting already existing ecosystems.

Speaker 9 (15:00):
Yes, I think we can if the exoplanet has the
right habital conditions, and you could maybe put the organism
of the life on the planet. So I think yes.

Speaker 2 (15:14):
I was impressed by all the different angles the listeners
came up with to address this question, like, well, it's
really far away, is that going to be a problem?
You know what would the environment need to be like
for them to survive? Lots of cool ideas from the
listeners on this one.

Speaker 1 (15:28):
Yeah, exactly, lots of different scenarios. Can we get it there?
Would it survive? Why should we even do it? And
so I think we should start with your question there, Kelly,
But like, what is the motivation here exactly? Like why
would you build a little rocket, put a bunch of
bactery in it and send it to an exoplanet? What
exactly is the goal you're trying to achieve?

Speaker 2 (15:46):
I mean, so, I personally am a big fan of life,
and I'd like there to be lots of life and
lots of biology everywhere. But I feel like it's complicated
when you get to adding biology to places that it
doesn't necessarily belong. I don't like invasive species very much
here on Earth and like less of that. So are
we like doing the ultimate experiment in invasive species?

Speaker 1 (16:10):
I think there are lots of possible angles here. I
think maybe the most generous motivations are just the ones
you expressed, Like life is awesome, Let's have more of
it in the universe. So imagine you could find some
currently sterile planet where there is no life, and your
confident life would not arise naturally, why not see it
with life, turn it into a petri dish, see what

(16:33):
would happen, and potentially creating biomes that might be habitable
for humans in a deep, deep future. Now, way, you
wouldn't be displacing any current life, so you don't have
to worry about the ethics of like invasive species and colonialism.

Speaker 2 (16:45):
But so that assumption is a really hard one for
me to accept though. So, like, you know, we are
not even one hundred percent sure that there's no life
on Mars. You know, it might still be in like
the lava tubes or something sort of like hiding out.
So it's even harder for us to study far out exoplanets.
How could we ever convince ourselves that a planet is

(17:06):
sterile and definitely doesn't have life when we only know
what life looks like on our planet and we can't
even tell you if there's life on the planets in
our Solar System. So I would have trouble believing we
could ever get certainty about that assumption. But what do
you think?

Speaker 1 (17:19):
No, I agree with you, And it sounds like the
set of for a science fiction novel where scientists get
humbled because they didn't understand what life could be. Then
they marched forward with their hubrisk too quickly. I agree,
we don't know what life could be like in the universe,
so it's hard to be certain that any planet really
is sterile. It's also basically impossible to be certain that
if planet will always be sterile. What if life was

(17:39):
going to evolve next week and then you showed up
with your zillions of microbes and you now made it impossible.
That's not something you can ever probe, right, especially because
we don't know how common life is and how likely
it is to be created from non living environments. So
it definitely would be taking a gamble. But I think
the motivations are the ones we expressed earlier. It's just like,
wouldn't it be nice to have more life? Imagine if

(18:01):
we are the only life in the galaxy and there
are all these habitable worlds out there with nothing on them,
that does feel like kind of a waste.

Speaker 2 (18:09):
It does, And you know, some of my favorite life
is life that I can eat. And so after the break,
let's talk about whether or not we can create essentially
grocery stores on other exoplanets. In case we ever decide
to go shopping there. Okay, so we all agree life

(18:40):
is awesome, and as long as we're not wiping out
other life, it might be cool if there were more
life in other places and we could sort of see
what kind of amazing biodiversity ends up being created in
new environments. But let's talk about being able to eat
that biodiversity. So, say we were seeding other planets in
case humans ever come along, what do you think I
think the chances are that you see to planet, Like,

(19:02):
how long do you need to wait before you can
harvest it?

Speaker 1 (19:04):
Yeah, that's a great question because I think you've pointed
out to me many times and it's described in your
upcoming book. If we do land on another planet, we
need to find some way to be self sufficient. You
can't rely on like shipments from Earth forever, which means
you need to be able to create your food locally,
which means you need like a whole biome. You need
like plants, and you need microbes. You need all this

(19:26):
stuff to create your life, and that's difficult to arrive with.
So it'd be wonderful if you showed up and there's
like plants or at least microbes or you know, the
basic foundation of your ecosystem that you could build your
grocery stores on top of. And so in a few
minutes you'll hear an interview I did with a microbiologist
where asked them essentially that question, like how long would

(19:47):
it take to go from injecting bacteria into an ocean
to showing up and finding redwoods and dinosaurs, you know,
things that you could hunt and climb around on and eat.
And so you'll hear him say it's a very, very
long time. It's not something you could expect to do
in a million years, or maybe even in a billion years.
But you know, on this podcast, we are very forward thinking.
We are not just planning for our children and our

(20:09):
children's children. We're planning for the deep future of humanity, right.

Speaker 2 (20:14):
Infinite time horizons. Nothing here limits us.

Speaker 1 (20:18):
Which means we can ask for infinite budgets, right, I mean,
because like a dollar today is worth so much more
in the future. But I think the picture you should
have in your mind is the Earth is the only
place in the galaxy with life, or one a few places.
If life in the galaxy is rare and it takes
a long time to develop. Then it seems like an
attractive idea to take a little bundle of our microbes,

(20:41):
send it to another planet, have it developed life there,
because then it would be more life in the galaxy.
And also, as you say, it would be the kind
of life that we can eat, which is our favorite
kind of life, because you know, even if you show
up on an alien planet and it has some kind
of life, it's not guaranteed that you could eat it.

Speaker 2 (20:58):
What I don't necessarily even though it's guaranteed if you
could eat it, if it was growing somewhere else. You know,
it's not safe for us to eat all the life
on Earth. There are definitely mushrooms that you ought not
to eat. For example. You know, I guess the question
would be like how often do you see the planet
and it doesn't take how often do you see the
planet but you come back and it's filled with toxic
mushrooms or something like that, And so, you know, I

(21:19):
think there's lots of ways this could go that might
not be exactly what you want, but I think all
of those ways would be interesting, would teach us something
cool if I can ethically, you know, jump the hurdle
of feeling comfortable with this experiment.

Speaker 1 (21:31):
And you raise an important point earlier, which is like,
how do you know which planet is a good candidate
for sending your microbes? Which planets might have the right conditions,
or which planets might be sterile. And so there's a
group of folks it's called Project Genesis that have actually
thought this through and worked on a little bit of
the engineering to make this possible.

Speaker 2 (21:50):
Oh, tell me more about that.

Speaker 1 (21:51):
The idea is to do it in two stages. The
first is to send out a bunch of probes to
find good candidates, to gather data and beam it back.
So the first wave is like, go out there and
find planets in the galaxy which might be good candidates.
And then a second wave is to actually send the microbes.
And this is important because the first wave can be
a lot faster than the second wave because the first

(22:12):
wave doesn't have to stop at the planet. You can
just do like a quick fly by and see these.

Speaker 2 (22:18):
Planets and then shoot the data back.

Speaker 1 (22:20):
To us and shoot the data back. And this has
to do with the physics of interstellar travel. Right. All
of these stars, even the ones close to us in
the galaxy, are pretty far away, like the nearest star
is like four light years away, and the whole galaxy
is one hundred thousand light years across. So getting from
star to star takes a long time because it takes
you a long time to accelerate anywhere near the speed

(22:42):
of light. So even getting to the nearest star could
take you thousands of years, especially if you have to
bring with you all the fuel that it takes to accelerate,
and the more fuel you bring with you, the more
fuel you need because you have to accelerate all that fuel.
See very quickly, have extraordinarily expensive.

Speaker 2 (22:59):
Rock, So even that first pass is not going to
get done in our lifetime. And I can imagine it
being super frustrating to like put a bunch of equipment
on there, and then five hundred years later you're like, oh,
we wish we had put this other piece of equipment
on there, but I guess you'd make do with what
you had. Are there options that don't require just like
ridiculous amounts of fuel.

Speaker 1 (23:21):
There are some really clever options, and we've talked about
in the podcast once before. There's this plan for something
called a solar sale. The idea is, don't bring the
fuel with you, don't load up a rocket with fuel
and then need fuel to push that fuel and fuel
to push that fuel. Don't bring any fuel at all,
have all the power come from the sun and just
have a sale. The solar sale is just a huge

(23:42):
mirror and all the photons from the sun bounce off
of it and give it a little push. Photons are
these tiny little particles the quanta of light, and they
have no math to them, but they do have momentum,
which means when they bounce off of something and go
the other direction, they give that something a kick. Like
when you're standing in the sun, the sun is literally

(24:03):
pushing on you with all those photons. It's a very
gentle push, which is why the sun doesn't usually knock
you down except in southern California in July, but it
is there. And if you had a very lightweight spacecraft
and a very large sale, you could accelerate up to
near the speed of light pretty quickly.

Speaker 2 (24:19):
That sounds like it's even faster than the method that
uses fuel.

Speaker 1 (24:23):
Is that right, Yeah, exactly, it's much faster than the
method that uses fuel. The disadvantage is that there's no
way to slow down, like this thing can accelerate up
to near the speed of light and then it can
whiz by your planet very very quickly, but it could
take some pictures and it could send you some information.
That's why this first phase is just information gathering and

(24:44):
then beam you back the data of course at the
speed of light. So this first phase where you like
go out and look at planets, you say, like is
there oxygen on them? Is there water on them? What
is the basic environment? Like this could be a very
quick survey.

Speaker 2 (24:56):
Okay, So if you're doing these surveys, what kind of
things are you looking for? I assume oxygen. Well, I
mean there's bacteria that don't require oxygen, but I guess
if the plant is you're seating it for food, you're
gonna want there to be oxygen for us. So probably
you want a planet with oxygen.

Speaker 1 (25:13):
That is the first and the hardest question, like do
you want planets with oxygen or without oxygen? And it's
interesting to think about, like where planets do get their oxygen.
Are their planets out there that are sterile but have
oxygen or is oxygen purely just a product of life?
And it's interesting because actually most planets do have oxygen
on them very very early in their life cycle. Most

(25:35):
planets are made with water because water is everywhere in
the universe, and in the early phase of the life
cycle of a star, they tend to emit a lot
of ultraviolet radiation. This is part of their life cycle
called pre main sequence, like before they settle down and
really just doing all their steady burning effusion, they emit
a huge amount of ultraviolet radiation which can break up

(25:55):
that water and produce oxygen. So very early in the
life of a planet do get some natural oxygen without
any life right, so you can get planets with oxygen
on them. The problem is that for a lot of stars,
this early phase is not very long. It's just a
few tens of millions of years, so it doesn't make
very much oxygen. And because you're blowing off so much

(26:16):
solar radiation, a lot of the atmosphere of a planet
can just get blown off. And this is what happened
to Earth. We had a little bit of oxygen made
early on through this UV light from the Sun, but
then the Sun basically blew away our entire atmosphere that
was the one that was formed with the original planet.

Speaker 2 (26:31):
Whoops. So then do we want to send do we
want to send photosynthesizing organisms.

Speaker 1 (26:38):
Then well, it's an interesting question, right, Like on Earth,
life started without any oxygen because the atmosphere was replaced
by volcanic outgassing which got nygen and CO two, and
then photosynthesizing organisms did create oxygen. But it's interesting because
a lot of biochemists tell you that having oxygen makes
it harder to form life, Like a lot of the

(26:59):
chemical building blocks of life couldn't have formed if you
had a lot of oxygen in your atmosphere. That the
anaerobic procedures are actually more important and they're inhibited by
the presence of oxygen. So if what you want is
to start life on a sterile planet, you probably don't
want oxygen. But if you want to seed it with
life like hours, then probably you do want to find

(27:22):
oxygen rich planets because they're more conducive to our kind
of life, and they're probably sterile because the oxygen is
like poisoned to those early forms of life.

Speaker 2 (27:32):
So how do you know that the planet you're seating
hasn't like progressed as far as Earth and that's why
it's got oxygen? I guess because your flyby was that accurate.

Speaker 1 (27:42):
Yeah, on the flyby, you're going to do more than
just test for water and test for oxygen. You can
also look for methane, for example. Methane and oxygen together
are a pretty good signature of life. You know, you
can look for phosphine. It's a whole really difficult question
of like how do you know if there's life on
that planet? But I think in general, looking for oxygen
rich planets that don't have obvious signs of life is

(28:04):
a good target because oxygen tends to prohibit the formation
of early life. And it turns out it actually is
possible to have planets with lots of oxygen that isn't
produced by photosynthesis.

Speaker 2 (28:15):
And where do we get it from?

Speaker 1 (28:17):
So there are a few different ways that planetary scientists
think that it's possible to have a bunch of oxygen
on your planet and not have it be blown away
in the early life cycle of the star and not
have it come from photosynthesizing life. There's a few different
configurations that at least their models tell them this can happen.
In like, if you have a planet that has a
huge amount of water, like a water world, then all

(28:39):
that water will put pressure on the crust of that planet,
which basically shuts down the geologic activity like all the
plate tectonics and the volcanism that we have, and it
slows down the weathering and the melting of the rock.
Both of these things absorb oxygen from the atmosphere, and
so if you have a huge amount of water, you
can shut down these sort of like oxygen slurping mechanism.

(29:00):
Like you know, rocks out there on our planet have
rusted because they have oxygenated. All the weathering of rocks
on the surface of the Earth has slurped a huge
amount of oxygen out of our atmosphere. So if you
have a planet where you basically suppress the oxygen slurping mechanisms,
then you can maintain some of the oxygen in the atmosphere.
That's sort of like one mechanism to make an oxygen

(29:21):
rich exoplanet without life on it.

Speaker 2 (29:23):
So to get an oxygen rich exoplanet without life, you
can do it by having tons and tons and tons
and tons and tons of water. Can you get more
dry versions or does it always have to have loads
of water?

Speaker 1 (29:34):
Yeah, exactly, you can. The sort of desert planet can
also do that. If you have a little water, but
not in zero. Then you end it with like a
solid surface and a lot of steam in the atmosphere.
It gets very very hot, and all the water becomes vapor.
It provides this like big reservoir of oxygen in the atmosphere,
and then the sunlight breaks if the water molecules, the
hydrogen floats off to space because it's very light, and

(29:56):
the oxygen sticks around. And if the planet has like
a solid desert surface, it can't weather, it can't absorb
that oxygen, so then the oxygen stays in the atmosphere.
So you have either like water World or a desert
planet with like a steamy atmosphere.

Speaker 2 (30:11):
All right, is there anything in between? Or those are
the two ways you get high oxygen environments.

Speaker 1 (30:16):
There is one other speculation. If you have a planet
that has like a very high initial ratio of carbon
dioxide to water, then you end up with a runaway
greenhouse effect, sort of like Venus. It gets super duper hot,
and you have no oceans because all the water is
turned into steam, and you have no volatiles in the
planet's mental because it's too hot. These voltules would do

(30:36):
the same thing of like sequestering all the planetary oxygen
through chemical reactions. Instead, the voltules are now in the
atmosphere where they're unable to remove the oxygen. They're having
a really significant runaway greenhouse effect. Is another way to
suppress some of the oxygen slurping mechanisms that would normally
remove oxygen from an atmosphere. So either you have a
water world or a desert planet, or you have like

(30:58):
a crazy venous green house effect.

Speaker 2 (31:00):
Well, frankly, I don't want to live in any of
those environments, so I'm hoping whatever microbes we dump makes
everything a lot nicer, much longer. After let's take a
break and then we'll talk about one other nice option
for where we could be seeding our microbes. Okay, so

(31:28):
there's one other nice option for places we could see.
Maybe maybe there's more than one, but one that we're
going to talk about today, And those are planets that
have these short windows of time as they're sort of
developing and going along where they might be a nice
place to seed with earthy microbes. Could you tell us
about that?

Speaker 1 (31:45):
Yeah, I remember. The big idea is to look for
places where our life might survive, but life wouldn't grow
on its own. Where we're not displacing native life like
original species. So one idea is oxygen rich steroplanets because
the can prevents life from arising. The other is to
look for places where life doesn't have time to arise,

(32:07):
like it might be that there's enough time for us
to seed it with life, which could then take off,
but there aren't like the billions of years it would
take for life to start on its own. An example
of that are brown dwarf systems. Brown dwarf is a
star that's not hot enough to fuse the way that
our star does. It doesn't have enough mass, so there's
not enough internal temperature for fusing to kick off. So

(32:27):
they call these sometimes a failed star. They're just big
blobs of hot gas and they're hot, but they're not
fused and they're not glowing right. This does provide some
temperature to create a habitable region for your planet, and
it could remain habitable for like a few hundred million
years or a billion years, but not like a long
time the way that our Sun and our Earth has
many many billions of years as a window. So the

(32:50):
idea is to look for brown dwarf systems where life
could survive but maybe it doesn't have enough time to
develop on its own and seed planets in those systems.
It's a place where, like our life could again survive,
but we wouldn't be displacing any native species.

Speaker 2 (33:06):
But so then we would need to move our life
somewhere else. I mean, I guess it would have millions
or billions of years, and so it would have some,
you know, time to run its course. But I mean,
is that enough time where we could imagine that something
we could eat could have developed, and that that would
be a useful run for the experiment.

Speaker 1 (33:23):
Yeah, exactly. So you send our life there and it
has enough time to flourish and develop and do something
before we arrive and set up our grocery stores.

Speaker 2 (33:31):
Okay, I know, I feel like there's still a part
of me that feels like it's enough time for our
seated microbes to do their thing. That should be enough
time for life to potentially arise on its own there.
So I'm not one hundred percent convinced that we wouldn't
be snuffing out some other possibility for the start of
life on another planet. But am I missing the point?

Speaker 1 (33:52):
No, you're not at all. And I totally agree all
these calculations. Assume that life takes a long time to start,
and if it doesn't, if pretty quickly when there are
good conditions, then all these places potentially could have life
already or could start life any moment, right, And if
you see them on a Tuesday, you could be displacing
life which would have started on a Friday. And so

(34:12):
before we do this, we definitely need to understand that
a lot better before we're confident in saying like, oh,
this is a steril place and it's unlikely for life
to arise anyway.

Speaker 2 (34:21):
Okay, so let's assume that we've convinced ourselves we found
a sterile place that we feel comfortable seating microbes. How
do we get the microbes there? I assume some of
the methods that we used to survey could also be
used to deliver microbes.

Speaker 1 (34:36):
So it's a great question how do we deliver the microbes? Right?
Say you actually have this little blob of stuff and
you want to send it to a planet around Alpha
Centauri or something where we talked about earlier. The solar
sale is great for getting up to high speeds, but
it's not so great for breaking. You don't want your
microbes to hit the planet at like ninety five percent
of the speed of light, because then they'll just like
core sample the planet. Right. They need a gentle landing

(34:59):
if you're going to spurse them, sprinkle them on top
of the ocean. Right. So somehow you have to figure
out how to slow down. You don't just want to
accelerate and zoom through the system. You want to arrive
at a gentle speed.

Speaker 2 (35:11):
How do you do that?

Speaker 1 (35:12):
Yeah, it's tricky, But there's a really cool technology called
magnetic brakes, which are very similar to a technology that
you and I talked about in that science fiction novel
Orbital Cloud. Remember that they had this technology in that
book to maneuver satellites by using the Lorentz force. They
had these long space tethers, these long wires. If you
put a current on the wire, it would interact with

(35:33):
the magnetic field of the planet and put a force
on the object. It's a very similar idea here. The
physics is fundamentally the same, though the mechanism is a
little bit different. What you do is you bring a
loop of wire and you make a current. That current
makes a magnetic field, and you can use that magnetic
field as a break because space is actually filled with

(35:53):
stuff that you can push against. Because the Sun is
not just putting out photons, it's putting out protons. Part
of the solar wind are these charged particles, these protons
flying through space, And as you approach this distant system,
you can turn on this magnetic field which will push
back against all of these protons in a way to
slow you down.

Speaker 2 (36:13):
Could you turn on the magnetic breaks from Earth? Like,
how do you make sure the breaks don't turn on
too soon?

Speaker 1 (36:20):
I got no breaks, No breaks exactly. No, it's important
that you time this right. And yeah, you could turn
this on from Earth, or you could preprogram it to
know where it is, or you could detect a certain
level of protons. There's lots of various ways to turn
it on. But yeah, you could send this thing messages
which would catch up with it because it's not flying
at the speed of light, and so your photonic messages

(36:41):
from Earth could always catch it. Now, unlike a solar sale,
which people have built and tested, magnetic breaking is a
little bit more theoretical. Nobody's ever built one of these
things as far as I could tell, and demonstrated that
it could actually work out there in the environment of space.
But in principle, we have some ideas about how to
do this. How to send something they are really really
fast and slow it down in time to enter the system.

Speaker 2 (37:04):
Okay, so let's assume that we can send something out
to our chosen exoplanet and we can stop it so
that we don't accidentally core the planet. Like, how do
you pick which microbes you send?

Speaker 1 (37:16):
Yeah, that is a great question. What do you send?
How likely it is to survive? You send one thing?
Do you send ten thousand different things? You send more
of one than the other? How does this all work?
What do microbes need? Anyway? So I didn't know the
answers to these questions, so I called up a friend,
Will Ratcliffe. He's an evolutionary microbial biologist at Georgia Tech,

(37:37):
and he studies the evolution of multicellularity. Like how did
creators go from individual cells to working together as single organisms?

Speaker 2 (37:45):
You have such interesting friends. Let's hear the interview.

Speaker 1 (37:50):
So here's my chat with Will Ratcliffe. All right, so
then it's my pleasure to welcome to the podcast Professor
William Ratcliffe. Well, welcome to the podcast. Thanks very much
for joining us, Ah, thanks for having me. So will
we are talking about dropping a load of life on
some alien planet, some exoplanet, and I'm just wondering, like,

(38:13):
first of all, what are the chances of microbes surviving
If I take a bunch of stuff I've scraped out
of sewage here on Earth or you know, from underneath
some trees or something in a forest, and I launch
them to an alien planet. Are they just going to
dry up and die? What are the chances that they
can survive?

Speaker 10 (38:31):
So the answer to this, I think really depends on
the existence of a few things. You need liquid water.
There's really kind of no getting around that. If you
have an exoplanet that doesn't have liquid water, ideally on
the surface, then it's going to be an uphill battle
for life. You might have things which persist but don't flourish,
but if you have liquid water, then it becomes a

(38:52):
question of what kind of energy sources and what kind
of carbon sources are available that for that life. We're
used to life that's sort of makes a living largely
either eating other things, which we do right. We take
large chains of carbon and break them down and get
both of our carbon, which is what we used to
build bodies and our energy, which is what we used
to power those bodies from those big chains of carbon.

Speaker 1 (39:14):
But there's actually a lot of different niches.

Speaker 10 (39:16):
That life has sort of evolved to take advantage of
and dissipate energetic equilibria and build bodies with carbon in
different ways. One that's really common and I think common
in the universe and really impactful is light, So you know, photosynthesis.
So being able to use light for energy is a
really common way of making a living because there's a
ton of energy in light and it's relatively straightforward for

(39:38):
organisms that have evolved the ability to use it to
just put it to work powering cells.

Speaker 1 (39:43):
But didn't we have life on Earth for millions of
years before we had anybody taking energy from photons?

Speaker 10 (39:49):
Yeah, it's a good question. It's actually it gets really
difficult to infer back that far. So we likely had
photosynthetic behavior pretty soon after the origin of life, although
again it's difficult to really see back beyond a couple
billion years. By two point one billion years ago, we
had had so much oxygen pumped into the atmosphere on

(40:11):
Earth that we oxidize our atmosphere and we have you know,
we basically couldn't absorb and react away any more of it.
But life arose around three and a half billion years ago.
But you're right, there's other ways to make a living
that don't depend on light. And in fact, if we
if we look at those, those are things which are
probably pretty common in the universe as well. So you know,
the main way that metabolism works is by taking something

(40:33):
which is at a high energy state and reacting it
into a lower energy state and using the energy that's
released to power metabolism. These redox reactions are common. There's
many different ways to do it. A simple way is
to take hydrogen, right and sort of burn it into
with oxygen and burn it into water. That releases a
ton of energy and that can be used to power metabolism.
You may not have oxygen, I mean hydrogen that's really

(40:55):
common in the universe, so I think we can assume
that there may be some hydrogen around, right. You may
not have oxygen, however, I'm one of these planets. Although
I will say on a planet that has a surface water,
it's not that unlikely to think that there will be
some oxygen every now and then. And that's because if
there's light, light will take water it'll break it apart,
you know, ulti volt light will break it apart. The
hydrogen will escape into space, and you'll be left with oxygen,

(41:17):
which is persistence time depends on whether it reacts with things,
but you can have oxygen around.

Speaker 1 (41:22):
So you're saying, we basically need liquid water, we need
some light, and we need some carbon and some hydrogen,
and then probably the microbes will be happy munching away
pretty much.

Speaker 10 (41:32):
And it turns out that we can even make it
less restrictive than that. You can take light off the table,
although I think you know, since planet's usually around stars,
light's usually not off the table, but you could take
it off the table. And if you have hydrogen or
if you have iron, those are also very common, very
effective sources of generating the electron flow during a redox
reaction that can power life. So there's life on Earth

(41:54):
that can literally rust iron and grow using the energy
that comes from that. That same life can take carbon
dioxide and fix it, meaning turn it into longer chains
of carbon, and so you can basically if you have
carbon dioxide and you have iron, or if you have
hydrogen and carbon dioxide, you are good. If you have light,
you are really really good. And if you have oxygen, light, iron,

(42:17):
and carbon dioxide, it's chill. You can easily have lighted well.

Speaker 1 (42:21):
As a physicist, I worry about other things, like levels
of radiation. You know, if this thing is getting like
impacted by huge numbers of cosmic rays, I worry about
them getting shredded. On the other hand, I have in
my head my wife's voice, and she's always telling me
that life survives everywhere. You know, they find it on
the outside of the Space shuttle and they find it.
You know, it's basically impossible to fully sterilize anything inside chernobyl.

(42:45):
You know, you find things that are rad hard. So
do we have to worry about these craters being fragile
or we're pretty sure if we have a big enough
sample that some of them are going to survive.

Speaker 10 (42:54):
I think it's not a big worry. If you have
a large sample, you'll have things that survive. Plus you
could have them in habit environments that are protected. You know,
Hydrothermal events on the bottom of the ocean, for example,
will buffer you from a lot of stuff, and then
organisms can evolve mechanisms that make them much more robust
to the damage to DNA that's caused by high intensity
waves and particles. So you know, a lot of organisms

(43:15):
like tartar grades are often touted as a cool example
of something which is robust to DNA fragmentation.

Speaker 1 (43:21):
They've evolved a lot of.

Speaker 10 (43:22):
Cool mechanisms that can take DNA that's been busted into
a bunch of small pieces and reassembled in a pretty
accurate manner.

Speaker 1 (43:29):
All right, So say you're tasked with developing this payload.
We're going to drop it on some random alien planet
you know very little about, just because you've seen maybe
some spectroscopy from its atmosphere. What cocktail do you recommend sending?
I mean, should we just scoop up a sample from
a local forest? But does it really matter if they're
all so hardy.

Speaker 10 (43:47):
I think it does matter in that you know, a
local forest, the surface of a local forest is probably
a very different environment than what you're going to find there,
and it's an environment that is not wet.

Speaker 2 (43:59):
Right.

Speaker 10 (44:00):
I think we're going to have our best bet with
something which targets oceans, because oceans are large, oceans are
relatively stable, and if let's hope that this planet has
surface water that's liquid and within those oceans. I think
I would have a mixture of things which inhabit both
the surface and our phototrophic so things which can photosynthesize
using light, and things which inhabit like seafloor niches where

(44:21):
they can do chemical chemical autotrophy, where they would be
basically breaking down hydrogen using hydrogen sulfide as an electronic
acceptor doing things which allow them to make a living
that is completely independent from a light based ecosystem.

Speaker 1 (44:34):
So then what do you expect we might get, Say
we drop this thing on an alien planet and we
come back in fifty million years, or our descendants eventually
make it out there on slow colony ships. Are we
going to end up with just like a frothing ocean
filled with microbes, or are we going to show up
and there's gonna be dinosaurs in redwoods, or you know,
some alien version of these things.

Speaker 10 (44:53):
Fifty million years is pretty short in the scheme of things,
so I think you're looking more at a frothing ocean
filled with mic growth, although they may terraform the planet
in the sense of creating eno foxygen. You know, the
amount of oxygen that we have in our atmosphere twenty
percent of our atmosphere that's all coming from life, right,
that's all coming from photosynthetic organisms. And so if this

(45:14):
planet doesn't have life already, if it's a steroplanet, there
won't be much, if any, oxygen available, Like the amount
of oxygen that we have is because of life. And
so I think if we could get you know, very
photosynthetically active ocean microbes. It might take a little longer
than fifty million years, but you could terraform the planet
in a way that would probably result in more of
an aerobic atmosphere, something which we're more happy with. But

(45:36):
to get something like dinosaurs and redwood trees and stuff,
I would probably actually jump the gun a little bit
here and see the world with more highly, more derived
organisms than just these bacteria which are hardy, which can live.
You know, bacteria are like the ultimate metabolic you know,
tool kit masters. If there is an energy source to
be dissipated, there's a bacteria or an archea, a single

(45:58):
cell organism that that has evolved to dissipate that. You know,
there's bacteria living miles deep in rocks eating only hydrogen. Amazing,
it's outstand You know, they might divide once every thousand years.
It's it's really cool. But these types of more complex organisms,
generally speaking, these multicellular organisms that we can see that
have you know, complex morphological features, they evolve from eukaryotes,

(46:22):
which are a different kind of organism that's actually the
result of a symbiosis between a bacterial cell and an
archel cell, and that symbiosis started on the order of
two billion years ago. And these organisms have compared to bacteria,
they have a lot more complicated subcellular features. They have
their DNA incased within a nucleus, they have more complicated

(46:44):
mechanisms for generating and moving proteins, and they have many
more opportunities for within cell gene regulation. And it's within
this more complicated kind of cell that you've gotten the
types of multicecular organisms that we know and love. Plants,
animal fungi, dinosaurs, redwood trees, and in fact, even those

(47:04):
lineages which have evolved pretty sophisticated forms of multicellularity, it
took them quite a while to do that. So animals
have been around for you know, on the order of
at least six hundred million years. Plants cropped up around
four hundred and twenty million years ago is kind of
when they got their start. Fungi have probably been around
for about a billion years, although it's hard to tell
when they became multicecular, but it often actually took quite

(47:26):
a while for this origin of.

Speaker 1 (47:27):
Multicecularity play out.

Speaker 10 (47:29):
But I will say, once you give them a toolkit
where they have the ability to have cells that remain
attached to one another and to specialize in different behaviors,
and you know, regulate that specialization through communication or other
bioelectric sensing in response mechanisms. Once they have those toolkits
for how cells grow into bodies and specialize and undergo

(47:51):
morphological novel morphological function, they can diversify very quickly from
that starting point. So I think what you'd want to
do is like see that world with maybe relatively hardy,
relatively simple plants, animals, and fungi, and then let those
things diversify into the various psychological niches that they find,
although you might actually have to do a sequential now
that I think about this sequential seating, hit them with

(48:14):
the basic stuff to get you know, a carbon rich
ecosystem going, and then toss in the more complicated stuff.
You know, a couple thousand years later.

Speaker 1 (48:23):
So what do you think is the most complex form
of life that might survive this kind of trip. I'm
imagining this thing is like frozen or desiccated and then
dropped in the ocean with basically nothing, and we hope
it just sort of reconstitutes itself. You can't do that
with like a dog, right or a tree. So are
we seeding this planet with tartar grades to come back
fifty million years later to find human size intelligent tartar grades?

Speaker 10 (48:44):
Oh, that's a fantastic question. So freezing things for interstellar travel,
like a lot of smaller organisms, there's probably a way
to work that part out of that too much difficulty.
You can freeze, you know, you can't freeze a fly,
but you can freeze you know, a number of smaller animals.
Certainly tartar grades would have no problem being desiccated and
shipped around the around the universe. But I don't think

(49:04):
that they're going to become you know, large and complicated.
They make their living basically sucking up bacteria plants. I
think I would take advantage of resting stages explores, inferns
or or you know, heart very very durable seeds of angiosperms.
That being said, I don't know what, if anything, could
survive these extremely sterile conditions that we would find ourselves

(49:25):
with on a new planet. I mean, I think I
think bacteria are really like they should do fine. You know,
if you throw enough stuff, enough different types of bacteria,
with enough different forms of metabolism at a blank slate
environment where there are energetic you know, conditions, energetic equilibria
to be dis equilibria to sort of be taken advantage
of and be used for energy, you're going to get

(49:46):
something which grows on that. But plants, animals, fungi, those
are all things which largely have evolved in the context
of an already pretty rich ecosystem of other organisms, and
they're highly dependent on those other organisms to make their living.
I mean, plants you might be able to get away
with in the sense that they are mostly self sustaining
photo autotrophic organisms that are growing on light, water and minerals.

(50:08):
But even plants are really specialized on growing on land
like plants are basically you know, we talked about, oh,
the invasion of land. Really it's the invasion of air
from a marine algae that was the difficult part for plants.
So I think you could probably if I was gonna
throw anything in there that was that was larger and
more complicated, it would be something like a seaweed, right,
because they're they're phototrophic, They're they're getting their energy from

(50:30):
the from the sun and minerals. There are many mutualistic
interactions that they have with other organisms. But I'm sure
you could find something which doesn't depend on those and
can grow azenically. And then once you have macro algae growing,
they create a habitat for many different organisms, lots of animals,
for example. So if I thought about this more, maybe

(50:51):
what you know, what I would do. I'm not sure
how you would ship this around the universe, But have
you ever seen those fully enclosed little ecosystems that have
some algae and some shrimp. I think they're Hawaiian and
they can live like in a completely enclosed, sealed glass
sphere for decades where that you know, basically you have
this nice balance between the oxygen that's produced by the
algae and the food that's created and the shrimp which

(51:12):
consume it and create carbon dioxide which the algae use.
It's pretty cool. So something like that maybe some small
invertebrate which is mostly grazier on algae or even eatings.
Think that might the single sid alogae which grow on
the surface of macrology and macrology and maybe try to
get that established. I don't know about just throwing it
into a sterilotionan, but if there was a way to

(51:34):
sort of, you know, have an incubator where you have
a near shore environment or a pond something a little
bit less big then subject to planetary scale weather.

Speaker 1 (51:48):
So is this an idea which excites you? You're like, ooh,
this would be really fun to see what happens. Or
is something that terrifies you the idea of you know,
polluting the galaxy with our kind of life. You know,
is it wonderful to imagine show up on this planet
and having like intelligent shrimp swimming in kelp forests that
we seeded, you know, long times ago.

Speaker 10 (52:08):
It's more exciting than terrifying for the simple reason that,
while we don't really know what the extent of independently
evolved the life on other planets is, it seems like
the amount of planets that exist vastly as strips the
amount of independent origins of life certainly complex life, and
so it doesn't seem to me that planets with liquid

(52:30):
water are necessarily a super limiting resource in our universe.
And so the opportunity to see how life would evolve
given replays of the tape, right to see how it
would independently go about colonizing a planet diversifying, I mean
you could. It would be It's a once in a
lifetime opportunity to see how something which starts over reconstitutes itself,

(52:51):
how a bioswear reconstitutes itself.

Speaker 1 (52:52):
So you want to turn the entire galaxy into your
own lab.

Speaker 11 (52:55):
Basically, I mean, you know, I wouldn't say no, that's
the exciting part, but I would say you'd have to
be very, very confident that there wasn't already existing life
on that planet before you went about doing this.

Speaker 10 (53:07):
I mean, if it truly was sterile, then I don't
think that there's a huge amount of downside, But a
lot of that depends on how confident you are that
it really is a sterile planet. And you know that
being said, if this planet's sterile, and it's been sterile
presumably for quite a long time, despite being habitable billions
of years, it seems unlikely that it would all of
a sudden not become sterile in the near future anyway,

(53:27):
So I don't know what you're giving up.

Speaker 1 (53:28):
All right, Well, thanks very much for sharing your excitement
and your insights with us. Really appreciate your time. It's
a pleasure. And of course I checked in with Katrina
and to see how much she agreed with Will. So then,
if microbes are so hardy, if we wanted to seed
an exo planet with life, could we just send anything
we want or do they need to be carefully chosen?

Speaker 4 (53:48):
I think diversity would be a better strategy than like
carefully choosing just one strategy, So I think you would
be better off. You'd be more likely to succeed by
gathering up microbes from a lot of different environments and
then sending as many different strategies out there, so you'd
get to roll the.

Speaker 3 (54:06):
Dice a lot more times.

Speaker 4 (54:07):
But I think you would want to pick from environments
that are already harsh and potentially similar to the place
that you're trying to bring the microbes to, so that
they would already be adapted.

Speaker 3 (54:16):
But yeah, if I had to pick.

Speaker 4 (54:18):
Between, like, you know, one lab evolving a perfect bug
versus just like sampling all of Earth's environments.

Speaker 3 (54:25):
I would vote Earth's environments.

Speaker 1 (54:27):
So I think Will's answer your question is that would
take a lot longer than fifty million years to get
from microbes to redwoods and dinosaurs and grocery stores.

Speaker 2 (54:37):
So I am not going to be shopping at the
brown dwarf grocery store.

Speaker 1 (54:41):
That's a bum no. But you are great gree kirkirk kirkkrekerk.
Great grandkids might be able to have dinosaur steaks for dinner.

Speaker 2 (54:49):
Thank goodness, the future is good. Okay, So, as you
may have been able to pick up throughout the course
of the conversation, I have some concern about this idea,
though I do find it interesting. So should we do it?
Let's end on that. So how about in our solar system?
What do you think should we ever do this?

Speaker 1 (55:10):
I think it's a hard question in general, but I
think that in our solar system it's pretty clear, Like, yes,
it'd be nice to be able to live on Gainy
Meede or on Io. But if we just send our
microbes and spray them all over the solar system in
the hopes of eventually having a biome that could support us,
we're ruining our chance to answer a much deeper, more
important question, right, like how hard is it for life

(55:32):
to start? Could life have started in other places in
the Solar system independently, or maybe life in the Solar
system actually did start only one place, but not on Earth,
and then came to Earth. If we sprayed bacteria microbes
all over our Solar system, we couldn't answer these questions.
We'll have polluted our backyard. And I think those questions

(55:52):
are more important than grocery stores on io.

Speaker 2 (55:56):
I think many people would disagree with you, especially when
it comes to Mars, because, of course, if we're going
to settle Mars, we are going to be seeding Mars
with all kinds of stuff, and depending on how soon
we do that, that might be before we even know
for sure if Mars has life on it or not.
So this is, you know, something that could possibly happen
in our lifetime. But do you think that the ethical

(56:19):
questions become or have a little clearer answers if we're
talking about other solar systems.

Speaker 1 (56:24):
Well, I want to get back to Mars actually, because
as a world famed skeptic on the possibility of settling Mars,
I have to ask you do you think it's possible
to settle Mars and not pollute it, Like, could we
set up some sort of barrier where we have like
an Earth region on Mars and somehow avoid contaminating the
rest of the planet or is that impossible.

Speaker 2 (56:46):
I'm not very optimistic that we could do that. So
you know, Mars has dust worms that blow dust all
over the planet, and you know, I think there are
microbes that you know, even if you said like okay,
no humans are allowed to, you know, cross this line
and half the planet is going to be pristine, I
think our microbes over time would sort of blow around
the planet. And you know, if there's no microbes there

(57:06):
then they're already then maybe that's not so bad, although
the microbes will start changing, you know, like the chemistry
of the environment, and that might make some scientists sad
who wanted to study Mars and it's like preserved states.
So you know, there's a lot of trade offs you
need to make when you're thinking about what to do
with another planet.

Speaker 1 (57:24):
Yeah, it really does seem like we have to decide
is Mars a scientific preserve or is it a resource
to be exploited.

Speaker 2 (57:32):
Yeah, and then the difficult thing is, you know, if
the US decides one thing, or in China decides another,
or Russia decides another, Like, can you get the whole
global community to agree on what we're going to use
Mars for? And I guess we'll see.

Speaker 1 (57:45):
Yeah, And not just governments, right, eccentric zillionaires can start
their own Mars colony outside of any jurisdiction. Right, there
are no laws on Mars as far as I'm aware.

Speaker 2 (57:54):
No, no, nope, nop nope. So if Musk wanted to
go to Mars, he would still have to like at
a permit through the FAA, and he would have to
like essentially get approval from the US government. And when
you're out in space, you are still the responsibility of
some government. So Musk would still be the United States' responsibility.
They should be telling him what he can or cannot

(58:16):
do out there. So you know, the Outer Space Treaty
is international law that is supposed to apply to when
humans go out into space as well. But you know,
is Musk gonna listen? That's a different question entirely. And
what would be the implications if he doesn't listen? Who knows?
Because the US could say no more.

Speaker 1 (58:35):
You're gonna throw him in Mars jail.

Speaker 2 (58:36):
That's right. I mean, so the US does have some leverage.
They could say we're not sending any more resupply ships
until you guys, you know, get your axe cleaned up.
But yeah, who knows what muscle will do when he
gets there.

Speaker 1 (58:47):
Yeah, so it's a tricky question here in our solar system.
In terms of other solar systems, I think it's related,
But for me, the balance tips a little bit in
the other direction. Like, there are so many planets out there,
I'm fairly confident we could find some that have no
life on them that we could use as experiments or
we could use to seed edible biomes for the very
future of humanity. Seems to me to be too restrictive

(59:10):
to say we can't explore or we can't experiment anywhere
in the galaxy.

Speaker 8 (59:14):
Yeah.

Speaker 2 (59:14):
I think if you could absolutely convince me that we
definitely knew what to look for and could absolutely determine
that a planet was sterile, you know, the evolutionary biologist
and me would love to see what happens if you,
you know, drop microbes and then come back, you know,
six billion years later, what do you have there that
sounds fascinating. It would be difficult for you to convince

(59:36):
me that it was definitely a sterile planet and we
weren't going to be, especially when it's you know, in
a different solar system. But if you could convince me
of that, then I would certainly be interested in seeing
this experiment run, not just because I love food so much,
but because I think there'd be interesting science.

Speaker 1 (59:49):
Yeah, because it would be a huge tragedy if there
really was like alien life on that planet and then
we sent our microbes and it like wiped them out.
What if we showed up and there were like fossils
of a dead civilation that we had killed with our
equivalent of smallpox.

Speaker 2 (01:00:03):
Oh, that would be awful. And also from like a
science perspective, like losing all of the data on like
when life actually pops up independently and the direction that
that took, as opposed to you know, what does our
life when you put it somewhere else. I think it's
much more interesting to see what happens when life pops
up somewhere else on its own, and then what happens
to it. But yeah, so many levels of it being

(01:00:24):
super sad if it turns out we're messing up what's
happening on some other planet.

Speaker 9 (01:00:28):
Yeah.

Speaker 1 (01:00:29):
If that happens, we should get thrown in space jail.

Speaker 2 (01:00:31):
Yes, yeah, except you know we will have long since
been dead because it will take so long to get
the microbes there. So I guess our whole species would
have to get thrown into space jail.

Speaker 1 (01:00:42):
Yeah, exactly. I think it's an interesting question even if
we never do it, right, even if we don't actually
do this, it's fun to imagine, like, how would it work?
What technology would you need? Is it even possible? To me,
it's fascinating that we're not actually that far from this
kind of technology, like solar sales. We could build that
and that it breaks. Probably that would work. Capsules of

(01:01:02):
ocean water which might survive the transit from here to there.
That's not implausible, Like this sort of science fictiony scenario
could be reality in the not far future.

Speaker 2 (01:01:13):
Yeah. We live in exciting times with exciting possibilities. I
hope we make the right choices.

Speaker 1 (01:01:17):
Since we're talking about some big moral choices. I asked
Katrina about the should we side of this question, and
how would you feel if an alien payload arrived with
their microbes hoping to seed our world with their bugs.
Would you feel invaded or intrigued?

Speaker 4 (01:01:35):
I mean, obviously intrigued, but how would I handle.

Speaker 1 (01:01:39):
I hope you're listening to that aliens.

Speaker 3 (01:01:42):
Yeah, and CDC. I hope the CDC is not listening
to that one too much. Actually.

Speaker 4 (01:01:48):
I mean, you would definitely want to do that kind
of work in a very careful environment, and we do
know how to work with pathogens. It's never perfect, though,
I mean, that's a whole other conversation. But you know,
I don't love hearing them there's small pox in a
freezer somewhere, and it's just one mistake away from getting
into contact with humanity again. And so not knowing what

(01:02:09):
the health impact or the environmental climate impact of a
new set of microbes would be, I would definitely want
to tread lightly, but I'd be super intrigued. Oh my gosh,
that's a dream to get to figure out how on Earth,
how on wherever they came from they do their metabolisms
and copy themselves, and I mean that would be fascinating.

Speaker 1 (01:02:32):
I hope you feel like you've made the right choice
in listening to me and Kelly talk about this question
for the last hour, and I hope that you learned something,
not just about whether or not Kelly is likely to
chop you up, but whether future humanity could and should
send microbes to other planets.

Speaker 2 (01:02:48):
I was the scary co host this time. Usually that's your.

Speaker 1 (01:02:50):
Job exactly now. I know what it feels like. Oh
my gosh, I'm quivering my boots, and I'm glad we're
across the country from each Others very much for joining us,
even though you threatened to slice me into pieces.

Speaker 2 (01:03:03):
Thanks very much for having me, for being a good
sport when the tables returned.

Speaker 1 (01:03:10):
All right, Thanks for listening. Everyone, tune in next time.
Thanks for listening, and remember that Daniel and Jorge Explain
the Universe is a production of iHeartRadio. For more podcasts
from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

(01:03:33):
you listen to your favorite shows.