Life on Mars has captured our imagination for many generations and we have wondered
what life would be like there even before H.G. Wells' novel "The War of the Worlds".
So, today we will tackle that topic.
We spent most of the Spring in the Upward Bound Series, looking at all the ways we might
be able to get into space faster, cheaper, and safer than now.
Once you get up there though the question becomes 'what now?'.
Now the usual answer is that you can colonize planets, and of course that is our focus for
this series.
Yet, it often seems like discussions of this spend most of their time talking about how
to get there or some small colony of five or six people or maybe even a hundred or so.
Which isn't much of colony honestly, or they jump all the way to terraforming the
planet with a population of millions or billions already.
I do want to spend some time on that phase of things, but the middle ground often gets
ignored.
So we'll discuss true terraforming but save a more detailed look at that for next month's
episode on Colonizing Venus.
Similarly, we often talk about the role of robots in space travel and colonization, and
it will likely play a big role in exploring and colonizing, but we'll save a more detailed
look at that for Colonizing Titan, after Venus.
Connecting this episode to those two and others which may follow, we will look at concepts
like trade for networking these places to each other and Earth.
A colony, besides just serving as more living space for us, really needs to have some commodity
it offers and others it needs.
We always want any given colony to be as self-supporting as possible but at the same time, it does
help to have trade to both optimize production and help keep everyone welded together.
A common feature in discussions of extraterrestrial colonies is them breaking off, so you get
Earth versus Mars, and we'll talk about that notion a bit today and throughout the
series.
Now you don't have to have seen any of the episodes on this channel to watch this one,
but it is a bit of a sequel to the Upward Bound series and our previous discussions
of Industrializing the Moon and Asteroid Mining are essentially part of this series too, so
if you haven't seen them yet, you may wish to watch them afterwards.
In any event, we are not interested in how to get to Mars, or what the ships that transport
people there are like, so we are going to jump to our colony already in progress.
One or more of the systems discussed in the Upward Bound series are in place and we've
got some orbital habitats around Earth and some serious resource extraction on the Moon.
In orbit around the Moon we have Borman station, named for the commander of the first manned
ship to orbit the moon back in 1968.
We'll assume the main base down on the Moon is Armstrong Base and the main hub close to
Earth is Gagarin Station.
We'll be spending a fair amount of time on Borman Station in the series as our jumping
off point to the solar system, so let me add that it is a rotating habitat simulating roughly
Martian gravity.
This was done for two reasons.
First, it gives folks going back and forth from Earth and the Moon a mid-point of gravity
to get used to the gravity at their destination; second, it lets us test the long term effects
of Martian Gravity on people, as well as construction and equipment tolerances for Mars.
A ship going straight from Earth or Gagarin Station to Mars might use a rotating section
that began at Earth gravity and spun down to Martian normal, during the trip, but we
will say most transit to Mars goes between Borman Station around the Moon to Mars.
Leaving from the Moon to Mars has some advantages, but the one we are mostly interested in is
that you can bring fuel and raw materials up from the Moon, and it's lower gravity
well, rather than Earth.
Plus, starting a major base on the Moon let's you prove it is viable before you start sending
people far further away from potential help.
Now we are going to assume we are not sending passenger ships to Mars at slow speeds, opting
for more energy intensive approaches, but for a large bulk cargo shipments around the
solar system you do probably want to use these most efficient approaches.
These can take years however, so it's great for moving bulk material around but not people.
When our ship leaves Borman station, it will be carrying a few hundred new colonists on
a trip of several weeks to Mars, which already has 3 principal settlements on it of a few
thousand people each.
This ship is the first of many planned ones now that a space elevator has been planned
on Mars.
This ship will be carrying it, and indeed it is going to become the new space station
hub for Mars.
As we've discussed before, it's easier to build elevators on lower gravity planets,
one on the Moon can be done with conventional materials for instance, Mars is harder but
a good deal easier than Earth.
We'll leave it academic if anyone has managed to make an Elevator down to Earth and assume
they have an Orbital Ring instead, but we will assume someone has made one strong enough
for Mars and that it got manufactured down on the Moon.
As mentioned, part of Borman Station's purpose was to test if people could handle Martian
Gravity in the long term, and it got started before the first Martian colonies did.
We don't know if 38% of normal gravity is something people can tolerate in the long
term but for today we will assume the answer was yes, just with some supplementary medication
and exercise.
Should that turn out not to be true, I think Mars would be unlikely to ever become a genuine
colony of Earth, or rather, you'd probably have a lot of rotating habitats around Mars
that considered themselves Martian, but the planet itself would basically be a place folks
spent time down on working there at mining facilities, not a home.
Sort of a reverse of the concept of a classic coastal city, everybody lives on the land
and many go to work in the sea, often for protracted periods, only here lots of people
work on the planet but everyone lives in orbit.
So for the last few decades since men first stepped foot on Mars they've been testing
this notion and concluded that indeed, this gravity is sufficient and, unlike on the Moon,
they don't need to use mixed spin and normal gravity for folks on the surface, something
we've discussed before, or cyborg people up.
Healthy exercise and some supplements are enough.
They've also got an orbital ring complete around Earth and a new production method for
carbon nanotubes to allow for a decently strong and cheap space elevator that can handle Martian
gravity.
With this in mind, the drive to colonize Mars has grown, and it is also economical to go
there for tourism, at least marginally economical.
Most people couldn't afford it and most who can don't want to, but at least many
thousands of folks can and do want to visit, so Borman station plans to start two-way trips
there leaving monthly with a couple hundred people each, many of whom will remain as colonists.
When this ship arrives though it is going to park in geostationary orbit, technically
areostationary orbit since it is Mars not Earth, but we will use geostationary in our
discussion of any orbit around any planet or moon that keeps hovering over the same
spot.
In our case, that will be 17,000 kilometers above Mars, closer than geostationary is for
Earth.
And they will hovering just over Pavonis Mons, a large mountain on Mars a good deal taller
than Mount Everest and quite close to the equator, in the Tharsis Region.
Humanity's first Martian base was near there and is typically just called Pavonis.
We will name the ship turning space station Port Tharsis.
The other two settlements are close by, a ways northwest at Olympus Mons, the tallest
mountain in the solar system, and the other in Valles Marineris, to the southeast, one
of the largest and longest canyon systems in the solar system.
Now by default you want to have a space elevator right over the equator, and indeed we will
place Port Tharsis right over the Martian Equator, but as we discussed in the Space
Elevators Episode, you can connect multiple tethers to the same space station that connect
elsewhere than the equator, balancing out their forces, much like guy wires on a tower,
so long as at least one of those connects to the north and south hemispheres each.
So while a single space elevator just south of Pavonis is an option, we will instead be
dropping three tethers down, then moving their ends to connect to the top of Olympus Mons,
to Pavonis, and to Marineris canyon settlements.
So they have three, which provides plenty of redundancy and gives us direct access to
space and vice-versa.
This is handy because while Pavonis is the oldest and biggest settlement, a lot of folks
at Olympus and Marineris prefer to keep their settlements independent, and until recently
Pavonis was the nominal planetary capital.
There's been quite a lot of arguing about that recently.
The original Mars colony was under the United Nations and since it can often take an hour
for a message to get to Earth and back with a reply, the security council has a commander
there who oversees things and is at Pavonis.
With all the new colonists arriving folks have been discussing something a little more
permanent and democrat and independent.
Back when it's just a few hundred people this was fairly laughable; they needed to
phone home for everything and everyone was a specially trained and vetted expert at something.
This is changing.
As we step out of the first landing car arriving at Pavonis down that elevator, they are proudly
celebrating their first café being opened, and as we look around at our other fellow
travelers, we are reminded of their own backgrounds.
Having spent many weeks traveling with them, we know them well enough and most are not
experts.
This is no longer a mission where the best and brightest can be selected and screened
for stability.
One of our companions is the new magistrate who is supposed to be replacing the former
magistrate who dealt with minor misdemeanors but there were very few of those and never
any felonies, so he spent most of his time helping people with legal documents dealing
with issues back home.
Divorces, trusts, wills, etc.
In a colony of several thousand it is a rare day at least someone hasn't had a family
member back on Earth die or had some sort of issue involving a relative.
Mars, the planet named for the God of War however, has just had its first big fight,
a barroom brawl off at Olympus over independence, and instead of replacing the magistrate, who
will be remaining in Pavonis, he is heading off to be the magistrate at Olympus.
The original colonists didn't have a lot of folks with legal or law enforcements backgrounds
among them, there's a lot of things they need to have, and at the same time they have
more than enough specialists from a lot of fields.
All of that is going to have to change as they transition from being an outpost to a
permanent colony.
But what about Pavonis?
What is this settlement like?
As a new colonist looking around, we do see domes and quite a few, but not as many as
we'd expect for a town of a few thousand.
But beyond those the view, while breathtaking, is quite barren.
Most of the settlement is in caves and lavatubes in and around the giant mountain.
Those domes are just for hydroponics.
Going inside, it seems a bit dreary even, and we find ourselves wondering what the appeal
is to come to Mars.
Oh sure, the first few thousand folks who came here did so for the simple motivation
of coming here.
People go to Mount Everest or Antarctica just to go there, but precious few decide to live
there.
In the short term that's not too big a problem, even if only 1% of 1% of Earth's population
wanted to come to Mars that would still be a million people, far more than the current
population, and of course once there they'll have children themselves and doubtless there
will always be more people wanting to come to.
And yet, what is the appeal?
What drove colonization on Earth?
It's very unlikely many folks would be sent to Mars as prisoners, as with Australia, or
to flee religious persecution as was the case with many American colonies.
There's no luxury crops like sugar or tobacco to grow in plantations on Mars.
Mars has plenty of iron, but so does Earth and the Moon.
It is a breathtaking place to vacation, low gravity with mountains that dwarf anything
on Earth and vast canyon systems too, and that's something since some folks might
visit, subsidizing the colony, and decide to stay too.
Its major export right now is curiosity, prestige, and wonder, which keeps the money flowing
from Earth, for now, but Earth doesn't particularly need anything Mars has.
Folks sitting around the new Pavonis Café discussing the future of Mars try to think
of stuff, but they mostly can only see things Mars can import or export to other planets,
and right now the only other planet besides Mars and Earth with any people on it is Venus
which has a small scientific outpost floating in its atmosphere.
There are also a few experimental mining operations in the asteroid belt and various robot probes
poking around the planets and moons of the outer solar system.
Trade, they think, has to wait on the rest of the solar system getting settled, and they
worry there might be a catch-22 in there, since the motivation to settle all the places
seems to revolve around other places already being settled too.
Of course they talk about terraforming Mars one day too, not just living inside mountains
and lava tubes and domes, and some say that it isn't even something far ahead in time,
but never, that there is no advantage or purpose to trying to give Mars its own atmosphere
and oceans.
That they should keep on just making new domes with air inside them and basically turn the
giant mountain they live in into one big arcology, essentially a giant mountain hollowed out
into a skyscraper.
The folks over at Marineris feel a bit differently though, and that's where we are bound.
We could, of course, take the elevator back up to Port Tharsis and back down to Marineris,
but instead we will be taking a ground vehicle.
The lack of any serious atmosphere makes flight on Mars very difficult, but it also means
high-speed rail is cheaper since there's not much air drag to fight.
That's going to be a while because while it would be very handy, building a few thousand
kilometers of track between Olympus, Pavonis, and Marineris won't be easy.
In some ways it is easier than on Earth, low gravity makes bridges over chasms cheaper,
and you can get away with much sharper inclines up and down craters and hills, but you've
only got a population of thousands, not millions, and you have to use a lot larger percentage
of your population for just basic food and life support here too.
Oxygen is plentiful enough, but it all has to be liberated from water or baked out of
rock.
Nitrogen for plants is hard to find, and every acre or hectare of crops you want to grow
needs a dome over it first, or artificial lighting if done underground in a lavatube
or cave.
You can't plant your crops in raw Martian dirt either, it has to be done hydroponically
or in soil made by taking that dirt and processing it in huge vats full of microbes and algae
first.
The notion of transforming Mars into an Earth-like planet is daunting to say the least.
It's not worth doing, says the driver, going on about how at Marineris they've decided
the future is in robust para-terraforming.
That's where you just slowly cover an entire planet over in domes, to keep the air in and
the local soil out.
Glass above, concrete below, and you just add dirt you've made into them.
They plan to eventually dome over the entire Valles Marineris cavern system.
The drive there is slow going, part of why they want that rail system, because there's
no gas station on Mars and no air for them to use to burn that gas anyway.
Everything is electric and battery operated.
They don't really have the manpower for building rail or power lines yet and Earth
said no to shipping those in.
What they're really hoping for back at Pavonis though is one of those new fusion reactors
from back on Earth.
They're big, heavy, and getting one to Mars would be a problem; but once here, they don't
need above ground domes anymore.
They could do all their growing in vast lavatubes and caverns that wouldn't need sunlight
then.
Valles Marineris is stunning in scope.
It's not that it is 4000 kilometers long, it's that it is 7 kilometers deep and at
its widest, over 200 kilometers.
It's almost incomprehensible, even in low gravity, to imagine a single bridge spanning
that, let alone a dome.
Fortunately our real destination is Noctis Labyrinthus, a series of maze-like smaller
chasms on the western edge of Valles Marineris closest to Pavonis Mons.
It begins just a few hundred kilometers southeast of Pavonis and its many smaller, narrower
chasms are filled with an icy fog.
This pilot project for terraforming has selected one of the narrower, shorter, and shallower
canyons, and they are busy walling up the end so they can dome the whole thing over
and pump in water from the ice in the area to make the first lake on Mars.
It's stunning to take in the scope of this dome, just a few kilometers long and wide,
and you are already wondering about cracks or meteor strikes on it and how they plan
to deal with them, let alone how they plan to build titanic ones across the wider parts
of the main Valles Marineris chasms.
As we settle in we start seeing four distinct viewpoints among the colonists.
Here in Marineris, the interest is all in domes: endless domes to eventually cover the
whole planet.
And the focus is on how to manufacture them and repair them and harden them against cracks
and meteor strikes.
Grids of radar and lasers to shoot down incoming meteors, possibly tall curtain walls around
the edges to help minimize erosion damage to the domes from dust storms.
Individual smaller domes connected with airlocks or great big ones with graphene supports and
liquid patches that could be rapidly sprayed on any crack or hole.
They envision not so much a Green Mars as a Greenhouse Mars: a 'worldhouse' as it
is sometimes called.
They point out that it is far easier to get all the nitrogen and oxygen they need for
atmosphere, when it is only maybe a hundred meters high, not kilometers.
If you want to have normal air pressure just from gravity alone, with no ceiling or walls,
you need to have a lot of air piled on top of air.
On Earth, every square inch of surface has 14 pounds of air over it, stretching many
miles, or 10,000 kilograms per square meter.
On Mars, because of the lower gravity, you actually need more air per unit of area, to
have normal air pressure.
That means your atmosphere has to go up higher.
On Earth, at the top of Mount Everest, it's fairly hard to breathe as the air has thinned
out a lot by that height, and the pressure dropped.
If we could transport Olympus Mons back to Earth, at 22 kilometers in height, the air
density wouldn't even be a tenth of what we are used to.
Conveniently on Mars, since the atmosphere would have to stretch up higher, you might
still be able to breath all the way at the peak of Olympus Mons, and still be able to
down at the bottom of those chasms, where pressure would keep rising, though odds are
they'd all be full of water anyway.
That's what the folks at Olympus Mons want, the second philosophical camp for Mars.
They want to terraform the whole planet, so you can walk around anywhere without a spacesuit
around you or a glass dome above you.
We're curious about them, though the folks at Marineris say they're all blue sky dreamers
and more than a bit batty, but we decide to visit them anyway.
To do so we first have to go back to Pavonis, and meet with folks from the other two camps.
One of them is simply the pessimism camp.
They think this whole idea was a mistake and they shouldn't have come here at all.
They are going home when the next colony ship arrives, there's always plenty of space
on those for a return trip, and they're irritated the most recent ship became Port
Tharsis instead.
They're basically loitering around Pavonis sowing pessimism.
They're still pro-space expansion, they did come here in the first place after all,
but they're thinking planets and moons besides Earth are for robots to live on, and people
should stick to arcologies on Earth or perhaps rotating habitats in orbit.
That's our fourth camp too basically.
They like the idea of having settlements down here on Mars but they think, now that there's
easy access back to orbit with the elevators up to Port Tharsis, that they can have just
a few settlements planetside but do most of their living up in orbital habitats, like
all the ones being built around Earth these days, and settlements here should be mostly
about comfort for the folks who need to be down here overseeing mining.
Yes robots would be handy but they still need a lot of oversight and a lot of times it's
just easier to use a person.
But they want nice, contained, truly Earth-like habitats and they figure all their other industry
and agriculture can be done on those in orbit.
There's no need to dome over the whole planet, let alone terraform it.
Just a few places here and there for mineral extraction, ice mining, and for the tourists
to visit of course.
Indeed, better to leave the planet mostly as-is.
They figure no tourist is going to want to visit domes; they want to see the natural
terrain.
They're all for a few of these projects, doming over a few chasms, having a few lavatube
habitats underground or in the mountain caverns, but they'd rather see Martian settlement
mostly happen in orbit.
They are somewhat open to the notion of terraforming Mars centuries down the road, but the way
they see it, they first need to get their industries built up and have exports.
This way, they can eventually pay for the huge amounts of nitrogen, and probably water
too, they'd need to bring in from other planets or comets.
So we set out on the much longer trek to Olympus Mons, and the last stretch is rather grueling
because they have set themselves up all over the mountain including the peak, and we do
want to see Mars from the peak of the tallest mountain in the solar system.
It is no surprise that there is a bar up there and it is the one the fight broke out at earlier
when we first arrived.
We run into our friend, the magistrate there, and share a drink.
He informs us that this is not the home of the second philosophical camp, the folks that
want to terraform Mars completely, but rather three camps who argue with each other a lot.
One group does want to terraform Mars, while the other group wants to bioform people and
plants on Mars.
And indeed, that's split into two subgroups as well.
One wants to set up an ecology where everything can live on native Mars dirt and not as thick
an atmosphere, less nitrogen than Earth too, but thicker than now.
Plants genetically engineered to use the native soil.
People engineered to live on thinner air and better adapted to the local gravity.
The other group wants to go completely native: organisms tailored from the ground up to live
on Mars as-is; people cyborged up to walk around without spacesuits, who don't need
to breathe and are safe from radiation concerns too.
Why, they say, should we put all the effort into making this planet livable to humans
and earth life, or even meet halfway in the middle, if we can just make new life that
can live here?
The magistrate seems to have been converted.
There's so many problems with terraforming he says.
The planet has virtually no air but when the duststorms come they are like a nuclear winter,
blackening the sky for days or even weeks at a time, so solar power can be unreliable
and plants need supplemental lighting.
If you get oceans and moisture in there, that would stop; but suddenly exposing the planet
to lots of water is likely to result in huge flash floods and tsunamis of mud, with no
plants and roots to hold them down.
It will never have enough gravity to be like Earth, even if we dropped every asteroid in
the belt and every moon around Jupiter on Mars, we still wouldn't increase the gravity
that much, and it would be kind of wasteful.
But even ignoring the gravity, we'd need to bring in air from elsewhere.
Sure there's enough oxygen, oxygen is plentiful pretty much everywhere in the solar system.
But not nitrogen.
The only abundant supplies for that besides Earth are Venus, Titan, and of course the
Sun itself.
But good luck lifting that nitrogen off of a star.
He points out that it isn't like moving a few colonists; we're talking about moving
atmospheres and those are pretty heavy.
Earth's atmosphere is 5 billion megatons, mostly nitrogen, and when we think of big
ships, even huge oil tankers, a single megaton is about as much cargo as they could carry.
If one arrived carrying a megaton of nitrogen every day, it would take 100 million years
to bring in enough nitrogen, and without a magnetosphere on Mars, it would probably evaporate
away before we finished.
No one wants to wait a hundred million years, so that means you've got megaton tanker
ships arriving not every day but at least thousands of times a day, or ships far larger.
And until near the end, there's not much use to that existing atmosphere, part way
through you can start adding water and possibly some tailored plants to get some basic ecological
cycles going.
During that whole time, inhabiting the planet still means living inside domes or caverns
and you'd have to worry about those being destroyed in the geological chaos of a planet
gaining oceans and atmosphere.
To keep that atmosphere there, we'll also need to ring the planet in satellites, sucking
in solar power to run electromagnets and create an artificial magnetosphere.
Mars is cold and far from the sun too, so you probably need to be considering orbital
mirrors to bring in some more light.
Those are both fairly hard tasks, though both are dwarfed by the task of bringing in all
that nitrogen and probably water too.
This is not a terraforming episode, we did one of those before and will look at such
concepts again in the next episode on Venus, but it is always good to remember that terraforming
a planet fundamentally alters it.
It's not the existing one just turning blue and green, all but the biggest landmarks are
going to cease to exist as sea rises and land slides under torrential storms.
No, this episode is about colonizing Mars and we see a handful of paths for doing that.
There's the terraforming route, make the place as much like Earth as you can, and as
we discussed in that terraforming episode you have tons of options depending on how
far you are willing to go, up to and include adding mass to a planet or changing its day
length or even moving the thing to be closer or further from a star.
If you've got the will to do it, and the resources, you can terraform Mars to whatever
degree you see fit.
But it requires orders of magnitude more effort to do that than some of our other options,
it's less finding a cave to live in then building an entire mountain on a plain so
you can drill a cave into it.
Possible but probably not ideal.
Bioforming is an option, but again it comes down to how far you are willing to go, just
in a different direction.
You might be able to limit yourself to fairly minimal tweaks to plants, animals, and people,
and meet halfway in-between, terraforming part way too, but once you open the door to
that path, there is the question as to why not walk down it further?
And how far is too far?
And since the path for meeting in the middle still takes many centuries at least, isn't
that likely to end up as a sliding standard as people move the milestones on what is acceptable?
If you are modifying people to the point that they can breathe easily in very thin air,
why not in no air?
And why not just go the full cyborg route and not need food or air?
In that context why do you even need planets, except maybe for raw materials, and maybe
why even a body at all, in favor of a digital existence in a virtual landscape of your choosing,
on any planet including surreal landscapes which are not physically possible?
And that is an option too.
So is the option of making Martian mean folks who live around Mars, and some who just go
down to work the mines or visit the place.
The slow disassembly of the planet to construct rotating habitats, built as needed.
I don't know which is best, I guess that will be for the Martians themselves to decide
down the road.
If I had to guess though I would wager on a little of all of the above.
There's a mistake in thinking for instance that you actually have to terraform an entire
planet or not at all.
As an example, the mountains, Pavonis and Olympus Mons, sit in the middle of volcanic
caldera, and when you think of things like caldera or craters you often think of a bit
of bowl with a rim around it.
There's nothing stopping you from extending that straight up, like the Great Wall of China
encircling a place only 10 or 20 kilometers high.
That sounds like an insane project, but it really is no different then doming over such
an area or manufacturing a rotating habitat.
You could then fill just that area with air and water, some would leak out, but just to
the rest of the planet, so you could build one that was decently small to begin with,
fill it with air and water, and just keep adding more to it, localized terraforming
that also slowly terraforms other areas if you want.
A similar concept is building up your atmosphere by doming over areas and just filling them
with new air and not worrying about what gets lost to leakage.
You don't necessarily need a full Earth Atmosphere on the planet either.
People can survive for short periods in much lower pressure than Earth's, and some organisms
might do just fine in it even without modification, and it doesn't take too much air to give
you a shield against most meteors.
People might get used to wearing masks when they go all the way outside, which might not
be too common if they just need to repair leaks.
Indeed since those various crack and spots near the leaks will be in between the local
native environment and the artificial one, it's not a bad place to experiment with
limited bioforming, the methods where you meet halfway in the middle.
Heck, there is even a chance we might find some simple life on Mars, unlikely but we
can't rule it out yet.
That of course raises the issue of whether or not it is okay to colonize a planet that
already has life on it, and if so, do simple microbes count?
But also, if we did find life there, it might be very valuable.
Odds are there are a lot more marginal planets like Mars out there in the galaxy than Earth,
and being able to use those, or some modified version of them, to help in early terraforming
might make them very valuable indeed.
I don't know what the future of Mars holds, but if I had to guess, if we checked back
on our colony in the year 3000, I would expect a little of everything.
Yes some Great Walls of Mars encircling some place that was genuinely terraformed.
Yes giant domes over chasms, with protection from meteors and self-sealing capabilities.
Yes smaller domes, yes big underground cities or hollow mountains artificially lit by fusion
power.
Yes some people who have modified themselves to live in the natural Martian environment,
or to meet it halfway in between.
And yes, a swarm of rotating habitats above, where people live and grow food and manufacture
materials for export and handle imports of giant ships carrying water and air.
Each one generating a magnetic field for its own protection and to act in concert as a
shield for the planet below.
Indeed each with its own defense grid to shoot down meteors that might hit them or the planet,
and orbital mirrors that bring in more light.
They might eventually have to choose to terraform all the way or not, to bioform or not, or
even to disassemble the planet for materials or not.
But for a very long time they could choose not to occupy somewhere in the middle but
the whole spectrum of options, if and until they decide which is best.
And as I often say when it comes to colonies, it's not just that we nowadays don't know
for sure which options are best, what with having never done it, but it isn't our decision
anyway, it's for the folks who live there to decide, and they have centuries to make
that decision and they can change it down the road.
They may be so removed from us by then that they don't want to be much like Earth.
We'll discuss making planets more Earth-like by terraforming more in our episode on Colonizing
Venus next month, but next week we will be returning to Earth and following up on the
Rare Earth Hypothesis notions that Earth-like planets are incredibly rare by asking if intelligence,
especially human level intelligence, might be quite uncommon to develop even on Earth-like
planets, in our close out episode of the Fermi Paradox Great Filters series, Rare Intelligence.
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