In some ways, Mars kinda sounds like a cool place to live, doesn't it?
The red soil, the craters, the dormant volcanoes.
Seems pretty scenic
And, if you chose the right real estate,
You could use one of the Viking Landers as, like, a lawn ornament, or something
But, of course, you'd have to be okay with temperatures around minus sixty,
An unbreathable atmosphere, and deadly doses of radiation
Which, for most people, are kind of deal-breakers
But, technology can do some fantastic stuff
And scientists who study terraforming, the science of transforming a planet to support human life,
Have put a lot of thought into changing these things
Turns out, with a few centuries worth of effort, we might be able to make Mars habitable for humans
But, I'm not gonna lie to you, it would be really, really, hard
A whole bunch of major things would have to change
Most importantly, Mars needs an Earth-like atmosphere
There are a few theories about how to create one
And they have a lot to do with the planet's history
In its younger days, about 4 billion years ago, Mars was actually pretty similar to Earth
It was warm, and wet, and had something of an atmosphere
That's because the Martian soil absorbed a lot of carbon dioxide and nitrogen that was floating around in the air
But, then, active volcanoes recycled those materials by baking them out of the soil
So, they could be absorbed again
The result of this was an atmosphere that mostly stayed put
Asteroids that kept hitting the planet helped out too, keeping it nice and warm
And, back then, Mars had a magnetosphere,
A planetary magnetic field that protected the atmosphere from being stripped away by solar winds
But, then the planet cooled, and lost its magnetosphere
There were fewer asteroid collisions, and its volcanoes stopped erupting
Without all that help, Mars' surface absorbed a lot of the compounds from its atmosphere
And lost most of what was left to solar winds,
Leaving a freezing, dry, barren, world
Sounds pretty bleak, I know
But, given what we know about Mars' history,
With a little tweaking, we might be able to bring that atmosphere back
Basically, we need to start a massive global warming effect
Something that humans seem pretty good at
And scientists have come up with three main ways to do it
The first, and easiest, way might be to just build factories
That would basically turn carbon, fluorine, and sulfur in the Martian soil into greenhouse gasses
And pump them into the atmosphere
This would unlock one of Mars' greatest assets when it comes to warming things up:
The think layer of dry ice, or frozen carbon dioxide, that covers its south pole
An initial burst of greenhouse gasses could cause this ice to sublime directly into vapor
Releasing carbon dioxide gas that would help trap more heat from the sun
In turn, releasing more greenhouse gasses
But, all that would take a while, and it would be tough to supply those facories with the resources they'd need
So, another method might be to build giant, 200-kilometer wide mirrors in space
They'd reflect sunlight onto the Martian icecaps,
Raising the surface temperature and releasing that carbon dioxide
If neither of those ideas worked, there's always the possibility of bombarding the planet with asteroids
In this scenario, we'd capture asteroids on the edge of the solar system,
And use rocket engines to propel them into Mars
The ammonia in the asteroids would act as a greenhouse gas
But, each asteroid would be like a 70,000 megaton hydrogen bomb
So, aside from the obvious logistic problems,
We'd have to do this way before humans were ready to set up shop there
And, even then, once the atmosphere had some greenhouse gasses in place,
It would still need an ozone layer,
A shroud of molecular oxygen that would absorb some of the sun's dangerous ultraviolet radiation
So, there would have to be, yet another, step
Where we introduce organisms like cyanobacteria or lichens,
Which would help enrich the soil and release oxygen, that could eventually form ozone
Once the ozone layer was in place, the final ingredient for an Earth-like atmosphere could be added:
Nitrogen
This could be introduced by asteroid bombardments,
Or bacteria could extract it from the nitrogen-baring compounds locked in the regolith,
The rock layer just above the Martian bedrock
Easy-peasy. Mission accomplished, right?
No. Not quite
Mars would also need a way to hold on to its atmosphere
And keep it from being stripped away by solar winds
Basically, it needs to get its magnetosphere back
Which is the biggest problem with terraforming
Because we really don't know how to do that yet
Earth has a magnetosphere which we're pretty sure is formed by liquid metals in the core
That create an electromagnetic field as they slosh around when the planet rotates
The same effect would happen on Mars if we could only figure out how to melt its core,
Which appears to be solid metal, not liquid
So, if anyone has any suggestions on how to liquify the middle of Mars, we're all ears
In the meantime, thanks for joining me for this episode of SciShowSpace
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Transcribed by Ethan M