AND PLUMES OF SUBLIMATING DRY ICE AT ITS POLES,

THE SURREAL LANDSCAPE OF MARS HAS CAPTURED THE EARTHLY IMAGINATION FOR CENTURIES.

BUT WHAT WOULD IT TAKE TO MAKE IT HABITABLE?

AS IN, A PLACE WHERE WE COULD BREATHE, WALK AROUND WITHOUT OUR BLOOD BOILING, OR EVEN

GROW CROPS AND ENJOY BLUE SUNSETS?

THERE HAVE BEEN SOME WILD PROPOSALS ABOUT HOW TO MAKE MARS MORE SUITABLE FOR HUMANS

FROM NUKING THE POLES TO HIJACKING A FLEET OF COMETS

IN ORDER TO KICKSTART A NEW CLIMATE.

SO, HOW CLOSE ARE WE TO TERRAFORMING MARS?

TERRAFORMING IS A TERM THAT WAS COINED IN SCIENCE FICTION.

BUT TODAY, THE IDEA IS BEING THROWN AROUND BY A HANDFUL OF ACTUAL SCIENTISTS.

- Terraforming, put simply, is changing the atmosphere and climate of a planet

so that it can support human life.

Without the need for spacesuits.

TO SURVIVE ON MARS, THAT IS, WITHOUT EXTENSIVE EQUIPMENT AND RE-SUPPLY FROM EARTH,

WE'D NEED TO BE ABLE TO DO A FEW SIMPLE THINGS:

BREATHE, STAY CONSCIOUS, AND NOT FREEZE TO DEATH.

IF WE CAN FIGURE OUT THOSE THREE HURDLES, WE’D HAVE THE LUXURY OF WORRYING

ABOUT LONGER-TERM CONCERNS, LIKE HOW TO GROW FOOD, OR

SHIELD OURSELVES FROM RADIATION.

TRUE, MARS DOESN’T SOUND THAT HOSPITABLE, BUT AFTER MULTIPLE MISSIONS WE’VE FOUND

CLUES THAT THIS WASN'T ALWAYS THE CASE.

- We see evidence that there was liquid water

running over the surface of Mars.

The atmosphere must have been thicker so that greenhouse trapping of heat from the sun would

warm the planet and allow liquid water.

- Most of Mars' atmosphere escaped to space over the last four billion years.

TO RESTORE IT TO A VERSION THAT’S MORE LIVABLE

FOR HUMANS, WE'D HAVE TO ADDRESS BREATHING FIRST.

ON EARTH, WE HAVE A DELICIOUS ATMOSPHERE MADE OF AROUND 21% OXYGEN, 78% NITROGEN,

AND A LITTLE BIT OF EVERYTHING ELSE.

It wouldn't need to be exactly that mix, but we would need a very similar amount of oxygen.

There certainly is enough water locked up in ice on Mars to get some O2 for you.

Unfortunately, there probably isn't enough nitrogen that we could easily get to, to build

up an Earth-like, mostly-nitrogen atmosphere.

If you're willing to wear a gas mask, then the gases could be pretty much anything which

isn't corrosive or acidic.

You'd have to carry oxygen on your back.

That could be an intermediate step.

OKAY, FINE – I’LL AGREE TO WEAR A DJ MARSHMELLO MASK FOR A LITTLE WHILE

IF I COULD SKIP THE SPACE SUIT.

SO, THAT BRINGS US TO OUR OTHER GOALS: STAYING AWAKE AND WARM.

AND IT TURNS OUT, THESE TWO ACTUALLY GO HAND IN HAND.

IF YOU STEPPED OUTSIDE ON MARS TODAY, YOU’D PASS OUT INSTANTLY

AND DIE SHORTLY AFTER, AS THE LOW PRESSURE LITERALLY PULLED THE OXYGEN

OUT OF YOUR BLOOD.

TEMPERATURES ON MARS SIT, ON AVERAGE, AT A CHILLY −63°C/−81°F.

BUT, IF WE COULD THICKEN THE ATMOSPHERE BY ADDING SOME MASS TO IT, WE MIGHT BE ABLE TO

KICKSTART A GREENHOUSE EFFECT THAT WOULD STABILIZE THE TEMPERATURE,

AND STAVE OFF SOME OF THAT DEADLY RADIATION, AS WELL.

THAT’S THE ESSENCE OF TERRAFORMING.

So the question becomes, is there enough CO2 anywhere on Mars that we can mobilize it

and put it back into the atmosphere?

- In terms of the very first sort of easy baby steps of terraforming Mars,

would be the release of the easily accessible CO2.

Now, this is the south pole of Mars here.

It's kind of hard to see there, but this is some water ice, but mostly CO2 ice down here…

if you started making the planet warmer, you would sublimate more of it.

Or you could just nuke it.

- The fast way is to drop thermonuclear weapons over the poles.

- That would only double the atmospheric pressure on Mars.

So we would go from 6% of the Earth's atmosphere to 12%.

And that's so not enough to heat up the planet.

OTHER SOURCES OF THAT DESIRABLE ATMOSPHERE FOR TERRAFORMING COULD BE HIDING IN MARTIAN

MINERALS AND DUST... BUT THEY’RE TRICKY TO UNLOCK.

Carbon-bearing minerals have to be heated up to several hundred degrees,

so you'd have to strip mine the planet globally in order to mobilize that CO2.

- Mars has 140 trillion square meters.

So that's about a million billion tons of gas that we would need dug up out of the ground

and then vaporized, or somehow released from those minerals.

And the energy required to do that is staggering.

You'd need the equivalent of running 10,000 gigawatt nuclear power plants constantly

for 10 to 40 thousand years.

NOW, WE MIGHT BE ABLE TO USE SOMETHING MORE EFFICIENT – A SUPER GREENHOUSE GAS

LIKE HYDROCHLOROFLUOROCARBONS, FOR EXAMPLE –

BUT WE’D NEED TO BUILD HUNDREDS OF FACTORIES

ON THE PLANET’S SURFACE TO PUMP OUT ENOUGH OF IT TO AFFECT THE CLIMATE.

THEN, OF COURSE, WE’D HAVE TO ADD BACK IN OUR CUSTOM COCKTAIL OF GASES TO ALLOW US TO

TAKE OFF OUR GAS MASKS AND OXYGEN TANKS, LET ALONE GROW ANY CROPS.

SO, LET’S INVESTIGATE OUR NEXT OPTION:

STEALING THE BUILDING BLOCKS OF AN ATMOSPHERE FROM COMETS.

There is a large source of nitrogen, oxygen,

hydrogen, et cetera, in the form of comets.

If you could redirect something like, depending on how big they are, ten thousand to a million

comets, and you were able to crash them into Mars on purpose… that would be possible,

given the distribution of comets that we have now.

- If you've got a million kilometer-sized objects hitting Mars, that would be pretty damaging.

It would probably devastate the entire surface.

- But really what you would need would be an army

of self-replicating robots that could essentially attach what people call mass drivers, which

would be, let's say, a nuclear power plant on a comet, which could be fed by the water

of that comet and then would use that same water as propellant to act like a rocket,

and over the course of years, redirect those comets to eventually impact Mars.

SOUNDS LIKE SOME PRETTY HEAVY LIFTING.

BUT WITH A NEW GLOBAL ENTHUSIASM FOR SPACE EXPLORATION AT LOWER COSTS,

WE MIGHT SEE SOME OF THE TECHNICAL ADVANCES REQUIRED TO INCH US CLOSER

TO THIS VISION – LIKE AUTONOMOUS NAVIGATION AND IN-SPACE ASSEMBLY OF SPACECRAFT –

SOONER THAN WE THINK.

BUT EVEN IF WE CAN BUILD AND MASTER ALL THIS TECHNOLOGY,

SHOULD WE CHARGE FORTH IN AGGRESSIVELY TAILORING THE SOLAR SYSTEM

TO OUR SPECIES' COMFORT ZONE?

AND HOW MUCH SHOULD WE PROMOTE THE IDEA OF HAVING A SPARE PLANET IN OUR BACKYARD?

- The danger in doing that is that we then

think that we can muck up the Earth and we have a place to go.

Given the difficulty of terraforming Mars, it's always going to be easier to keep the

Earth's environment habitable, to repair any damage we do, then to fix Mars.

SO WHILE WE WORK ON MAKING SURE OUR OWN PLANET'S

CLIMATE IS LIVABLE, ALL WE NEED TO DO TO FIX MARS UP IS FIGURE OUT HOW TO CREATE LEGIONS

OF ARTIFICIALLY INTELLIGENT ROBOTS,

WHICH CAN CREATE COPIES OF THEMSELVES OUT OF MARTIAN DUST,

TO HELP US SET UP MAJOR MINING OPERATIONS,

AND VAPORIZE A MILLION BILLION TONS OF ROCK.

OR BUILD HYDROCHLOROFLOUROCARBON FACTORIES.

OR CAPTURE, RE-DIRECT, AND CRASH LAND A MILLION COMETS ONTO THE PLANET’S SURFACE

WITHOUT COMPLETELY OBLITERATING IT.

SO HOW CLOSE ARE WE TO TERRAFORMING MARS?

Today, the emphasis is on getting a first human mission.

And even that is really hard and really expensive.

- Then we need to establish a scientific outpost, to show that there's some level of sustainability

on Mars as it is today.

Because we need to learn how to live on Mars as it is today before we can even begin to

think about terraforming.

The difficult part for me is seeing how we

get from the scientific outpost, that limit of 10 or 20 or 30 people, up to the kind of

10,000 people that it would take in order to really start the terraforming project.

- And that really requires a city on Mars.

Is that a hundred years into the future?

500 years?

To my mind anything beyond 30 years into the future is science fiction.

- I think the people who ultimately terraform Mars

are going to be Martians.

They will have been adapted by generations upon generations

of living in lower gravity.

They'll be a lot taller than us.

They might have different blood chemistry.

They will ultimately start to diverge somewhat as a species from us,

and evolution will slowly take over.

They're still going to be humans, they're still going to look like us, but

they'll be different enough from us that they'll be

easily identifiable as, "Oh, that's an Earther.

That's a Martian."

MARS MIGHT BE A LONG SHOT, BUT YOU CAN ORBIT

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