16:00

probably wouldn't work for the belt or outer

16:02

planets either, being further from the Sun. Same

16:05

for fuel production, at least for the asteroid

16:07

belt, though the implication would be

16:09

that you get off Mars by rocket,

16:12

mass driver, or space elevator, and

16:14

then ships moving from orbit to asteroid,

16:16

or orbit to some other moon or

16:19

planet's orbit, or using nuclear, probably

16:21

nuclear thermal propulsion. If

16:24

you get fusion working economically, which I would

16:26

tend to bet you would by the end

16:28

of the next century if it's even possible,

16:30

then that's probably what you are powering motion

16:32

cities with, and yet if

16:34

they are emerging from all the existing settlements

16:36

that predated fusion, their chosen locations are likely

16:39

to still be based on where they could

16:41

get that rocket fuel. So

16:43

what does a city of 5000 on Mars need

16:46

to look like? Well, obviously

16:48

you've got those power plants, and

16:51

if you do settle on the equator

16:53

and choose solar, you still probably have

16:55

a nuclear reactor for a city that

16:57

size anyway. Something in the tens of

16:59

megawatts would seem right, and we do

17:01

have some good small modular nuclear reactor

17:03

designs that also could be adapted to

17:05

Mars fairly easily. You might

17:07

have to have spinning sections to add

17:10

gravity, what we call bull habitats, but

17:12

my own guess is that Martian gravity

17:14

will be just fine for people, plants,

17:16

and animals. If not,

17:18

the habitation area of your city where

17:21

folks live and sleep is probably a

17:23

deep bowl that spins around under a

17:25

dome and everybody exits the habitation area

17:27

to the rest of the city or

17:30

outside by the middle axis, bottom

17:32

by tunnel or top by tower. You

17:35

might have fliers stationed at such a

17:37

tower or an underground subway to a

17:40

neighboring city or to some vehicle garage

17:42

full of rovers. Flight

17:44

does work on Mars, both planes

17:47

and helicopters, but getting enough

17:49

oxygen for an air breathing engine is

17:51

tricky so you probably go electric or

17:53

carry both your fuel and oxidizer like

17:55

a rocket does. You need

17:58

big wings as the gravity is lower. but

18:00

the air is so thin that you must

18:03

go either very fast or have very big

18:05

wings to get enough lift to stay airborne.

18:08

Flight is likely to be used, especially as

18:10

far away as many settlements might be, and

18:13

sturdy, pressurized all-terrain rovers would

18:15

also be common. You

18:18

probably would not have many large vehicles

18:20

inside early Martian cities. You

18:22

still have to move bulk freight, but it's

18:24

not likely to have the economy or supply

18:26

chains To be thinking about lots of personal

18:28

vehicles for folks to move around, they're a

18:30

relatively small town with. Plus

18:32

you probably have lots of segmented

18:35

domes connected by narrow and airlocked

18:37

passageways. We are prone

18:39

to imagining a city under a giant single

18:41

dome. Indeed such an image is

18:43

what we have for the original cover art that

18:45

inspired the episode, but it isn't

18:47

very likely. That said,

18:50

you might have a lot more underground tunnels

18:52

connecting things too. You

18:54

are not likely to see many roads and

18:56

highways on Mars, not unless our automation is

18:58

really good by then, which to

19:00

be fair it probably would be. Short

19:03

packed regolith roads to local buildings

19:05

outside the domes and maybe model

19:07

rails to major extraction sites or

19:10

other cities or larger outposts. The

19:12

dust situation on Mars tends to

19:14

get exaggerated, so no you don't

19:17

need to bunker down against dust

19:19

storms or constantly race around clearing

19:21

dust off your domes, solar panels,

19:23

or airlines. Figure

19:25

on landing pads and facilities being

19:27

relatively far from the actual habitat,

19:30

quite possibly a kilometer or more,

19:33

and either connected by a tunnel above

19:35

ground and pressurized or underground or

19:37

reached by some sort of buses and

19:40

truck with airlock connections for getting people

19:42

and cargo out. Long

19:44

telescoping tunnels and airlocks to reach ships

19:46

from some central landing bunker is an

19:48

option too. Spaceships

19:50

may be able to land perfectly smoothly and

19:53

gracefully in the future, but at the moment

19:55

they do not. At least not

19:57

reliably, and hopes to think of one as a

19:59

job. giant flamethrower attached to a warehouse

20:02

full of explosives that you're trying

20:04

to softly crash onto the ground.

20:07

So distant landing pads and bunkered

20:09

landing facilities are very justified. You

20:12

are quite likely to be building those in

20:14

the bottom of a crater or bulldozing a

20:16

rim wall around them too, just to serve

20:19

as blast protection. You would

20:21

probably do this on the Moon as well,

20:23

see our episode Moon, Crater Cities for more

20:25

discussion of that style. Hypothetically

20:28

you might build your city as a ring

20:30

inside that crater rim wall, or on the

20:32

outside of it. Odds are

20:34

good there'd be some useful resources there and

20:37

you could sprawl your agricultural domes out from

20:39

that ring. A city

20:41

built around a landing site might then

20:43

be literal rather than metaphorical, where we

20:46

normally assume a city forming a barbell

20:48

with the landing site or having on

20:50

the outside edge, rather than its center.

20:53

So too, the example of tall central

20:55

towers of helium from Barsoom might emerge

20:57

too, as we might have

21:00

cities built around the base of space elevators

21:02

or space towers. As to

21:04

building methods, that's all about how good your

21:06

automation is, which is why

21:08

I tend to have an easier time

21:11

believing Martian cities might be big and

21:13

often with large labyrinthine chunks underground, even

21:15

while early Martian settlements will probably need

21:18

to be very compact and even claustrophobic.

21:21

If you're looking for some good visuals of

21:23

what those might look like, my friend Brian

21:25

Versteeg's Space Habs Art is probably some of

21:28

the most common and inspiring pieces out there,

21:30

and always well-researched. I'll

21:33

also give a shout out to the 2023 book,

21:35

A City on Mars, by Kelly and

21:37

Zach Wienersmith, and the

21:39

folks over at spacearchitect.org who have

21:42

a lot of good Mars-based art

21:44

but in particular their Hive Mars

21:46

Hybrid Scalable Settlement and the newer

21:49

Martian City, a self-sufficient excavated vertical

21:51

city at the Cliffs of Tempemenza

21:53

on Mars, which has some stunning

21:55

visuals and animations, but caught

21:58

my eye particularly for today because we're going it's

22:00

aimed to be a full metropolis,

22:02

it's composed of individual macro-buildings designed

22:04

to accommodate 4400 people,

22:06

which is close enough to our 5000

22:09

minimums city figure I think. Those

22:12

macro-buildings are described as quote, inside

22:14

the rock of the cliff, each

22:16

accommodating 4440 people. These constructions, implemented

22:20

after tunneling, are modular and

22:22

include residential and work activities,

22:25

linked together by a three-dimensional

22:27

network of tunnels. The

22:29

modules have a tubular shape of 10

22:31

meters in diameter and 60

22:33

meters long, with two floors. There

22:36

are three different residential and

22:38

three work modules, providing a

22:40

highly flexible and scalable opportunity

22:42

by recombining the modules as

22:44

needed. By giving

22:46

this standardization, the design ensures

22:48

scalability and reduces complexity, costs,

22:51

and construction schedules. All

22:54

modules include green areas, urban

22:56

gardens, and spaces dedicated to

22:58

arts. The urban gardens

23:00

are small community parks with

23:02

animals and bodies of water

23:04

designed to provide physical well-being.

23:06

The macro-buildings on the cliff

23:09

are connected by high-speed elevator

23:11

systems, similar to skyscrapers on

23:13

Earth. This infrastructure also connects

23:15

the bottom of the cliff with the top

23:18

and has intermediate stops at the

23:20

sky lobbies that connect the macro-buildings

23:22

with a separate elevating system. The

23:26

highest point of the cliff is the mesa. This

23:29

vast plain contains the infrastructure

23:31

dedicated to manufacturing, food production,

23:33

and energy generation. Crops

23:35

will be grown in agricultural

23:37

modules with a CO2-enriched environment,

23:40

which will not be breathable for humans, and

23:42

as a result the operational tasks in

23:44

these facilities will be automated. A hydroponic

23:47

system increases the crop's efficiency as

23:49

it requires less water and space

23:51

than other methods based on above

23:54

ground crops. This sector

23:56

also accommodates the production of algae,

23:58

cellular meat, and bacteria for

24:01

waste processing." The

24:04

description continues and again you can see

24:06

the rest of it and others over

24:08

at spacealcotech.org. But

24:10

we inevitably come back to the same question.

24:13

What is subsidizing many thousands of

24:15

people living on Mars? In

24:18

theory it might be exactly that, a

24:20

subsidy. A more prosperous

24:22

and borderline post-scarcity civilization on Earth

24:24

might be quite willing to dump

24:26

billions of dollars a year into

24:28

securing a foothold on Mars and

24:30

pushing it till it became self-sufficient,

24:33

at which time it can't just keep growing

24:35

as fast as inhabitants feel like having kids.

24:38

If we assumed we sustained it till it got to be about

24:40

10,000 people, say in the

24:43

year 2200 AD, and

24:45

then that organically grew at 1% a year, then it's 27,000 people

24:47

in 2300 AD,

24:50

73,000 in 2400, 200,000 by 2500, and fully 36 million by the year 3024, a thousand years

25:00

from now. That's hardly

25:03

fast but I think it represents a

25:05

probable low-end conservative value of when we

25:07

could say a real populated Mars as

25:09

a settled planet would occur. On

25:12

the flip side, if you were sending a new

25:14

spaceship there every single day with a few hundred

25:17

people on it for about 100,000 a year and

25:19

assuming that same 1% growth rate that

25:23

still takes you a century to get to

25:25

16 million people, and that

25:27

would be on the high end of techno-optimism I

25:29

would tend to think. There

25:32

tends to be a big handwave gap

25:34

between a small or medium sized base

25:36

on Mars and a big planetary empire

25:38

rivaling Earth that happens in a lot

25:41

of science fiction. And I

25:43

think we might see our biggest city of Mars

25:45

not even be located on Mars but in orbit

25:47

around it, where ships coming and

25:49

going from the surface and coming and

25:51

going between orbit and other planets might

25:53

dock, without having to fight that gravity

25:56

well and the thin but still problematic

25:58

atmosphere. Indeed one of the terminus

26:00

of a space elevator up in

26:02

high planet stationary orbit might be

26:04

a twin city with its ground

26:06

station thousands of miles away, but

26:08

connected by the hyperfast bridge of

26:10

a space elevator. We

26:12

might call it upper and lower Barsoom.

26:16

While the gravity well and lack

26:18

of abundant volatiles doesn't make the

26:20

red planet too inviting for space

26:22

development, it is probably the easiest

26:24

place to just conventionally settle and

26:26

live on, compared to the floating

26:28

cities of Venus, mirrored mushroom habitats

26:30

of Mercury, or various asteroid mining

26:32

bases inside cylinder habitats crammed into

26:35

metal-rich rocks. So

26:37

I could see it being one of the biggest

26:39

jewels in the solar system's civilization down the road,

26:42

just not likely before we saw major

26:44

development in the asteroid belt or moons

26:46

of Jupiter let alone before the moon,

26:49

for the reasons we outlined in

26:51

our episode Moonforest vs Marsforest. Nonetheless,

26:54

sooner or late, I think we

26:56

do see a growing and eventually

26:58

large civilization on the red planet,

27:01

and eventually many people living in

27:03

the cities of Mars. One

27:09

alternative to heading out into space to

27:12

settle other planets like Mars is to

27:14

instead explore the multiverse, as

27:16

theories predict there may be near infinite

27:18

uninhabited versions of Earth out there, me

27:20

identical to our Earth but where humans

27:23

haven't evolved. But there's a

27:25

lot more options on multiverses than

27:27

just other timelines, and this month's

27:29

Nebula exclusive will explore all the

27:31

different multiverse options and the theories

27:33

they arise from. That's out

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now on Nebula where you can see

27:37

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riding alien horses around, on September

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28:51

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