[♪INTRO]

Lately, there's been a lot of talk about building a colony on Mars.

There's still a lot to do before we get to that point, like,

we should probably figure out how to get people there.

But even if we did set up a human habitat,

we'd still have some huge challenges to overcome.

Because traveling to, and living on, the Red Planet

would be more dangerous than basically anything we've ever tried.

Here are three of the biggest challenges the Mars colonists would, or will, have to face.

The danger starts long before reaching the Martian surface.

Depending on exactly when and how our astronauts launch,

it will take the crew somewhere around seven months to get to Mars.

And as soon as they leave the protection of Earth's magnetic field,

they'll be exposed to the intense radiation environment of space.

This radiation is mostly made of tiny subatomic particles like protons and neutrons.

Many stream out of the Sun as part of the solar wind, while others,

called cosmic rays, come from all over the galaxy.

And sometimes, these particles can strike a bit of DNA

as they pass through the human body.

Each hit can randomly change a little of someone's genetic code, and that can lead to mutations

in new cells that ultimately cause problems like cancer or heart disease.

Thankfully, because we're protected by the Earth's magnetic field and atmosphere,

we aren't exposed to most of these particles.

But things aren't the same in space.

Although astronauts take precautions, spending six months on the International Space Station

results in absorbing about three times as much radiation as the U.S. annual legal

limit, and a trip to Mars would be over twice as much as on the ISS.

And, if there happened to be an explosive solar flare during the trip,

the crew could receive a lethal dose of radiation in just a few hours.

Since Mars lacks a global magnetic field and doesn't have much of an atmosphere,

things don't get a lot better once the astronauts land, either.

Over about 500 Earth days, they would receive about as much radiation as on the trip there,

and that would really add up over a lifetime.

To protect our first interplanetary settlers, scientists have a couple of ideas

that would make MacGyver proud.

First, it turns out that water is very effective at absorbing radiation,

because it's rich in hydrogen, which is just the right size to block these subatomic particles.

And water is something the astronauts will already be bringing with them.

So one option is to line their spaceships and habitats with tanks of it.

Another option is tunneling underground to escape the radiation, or setting up shop in

giant, empty lava tubes left over from when Mars was volcanically active.

Of course, astronauts don't need to worry about radiation if they starve to death first,

and growing food on Mars won't be a picnic.

Well, actually, growing food might not be too terrible.

Laboratory experiments suggest that it is possible to grow plants in the powdery Martian

soil, and Mars' atmosphere is full of yummy carbon dioxide for photosynthesis.

What might be more tricky is not dying from the food you grow.

See, Mars' surface is full of perchlorates,

a class of salts considered industrial waste here on Earth.

Perchlorates overwhelm the body's thyroid gland by blocking its ability to absorb iodine,

which is normally used to produce a hormone that regulates your metabolism.

In the U.S., it's regulated in things like groundwater at the state level.

Massachusetts, for example, sets the legal limit at two parts per billion by mass.

Meanwhile, on Mars, perchlorates are found at a rate of

around 6 million parts per billion.

Which is just a tad higher.

Just like we can clean up soil here at home, it's possible to do the same thing on Mars,

like by introducing microbes that eat perchlorate as an energy source.

Which, of course, would run the risk of contaminating Mars with even more Earth life.

And that's a whole different problem.

So, either way, I'm gonna let you take the first bite.

To power all that soil cleanup, plus basically everything else,

settlers will need a reliable source of electricity.

The obvious answer is to just throw up a bunch of solar panels and call it a day,

but that could be a big mistake.

See, every year, Mars suffers from dust storms the size of Earth's continents,

and, on average, those cover the globe about twice a decade.

The thin Martian atmosphere means these windstorms wouldn't blow over the solar panels,

but all that dust flying around blocks an enormous amount of sunlight.

When the Mars rovers Spirit and Opportunity got trapped in the last global dust storm in 2007,

they were reduced to operating just a few minutes each day.

That's okay if you're a robot, but not so good if you need to do things like,

I don't know, breathe or see at night.

To get around this, the first Martian colonists will need to bring a different kind of power source,

like something based on plutonium,

because plutonium doesn't care if the Sun is out.

So, it's not that there aren't solutions to these problems.

We could clean up the soil, build radiation-proof habitats,

and figure out a reliable power supply.

The thing is, there are a lot of problems, and finding the answer to each of them

in a way that doesn't break the bank will be a real challenge.

But, hey.

People.

On Mars.

If we can get that far, we'll figure out the rest.

Now, even though solar energy may not be the perfect fit for a Mars colony,

it would still be useful.

And if you want to dive deeper into the quandary of powering a planet with solar,

our sponsor Brilliant has a cool lesson about just that.

Brilliant takes you through puzzles and quizzes as a good refresher on

how much solar energy we really have to work with here on Earth,

and how much we'd need to collect to power current human consumption.

Let's see if we can figure it out.

So one of the things I personally love about a Brilliant quiz

is that it starts off with some really basic information,

and then dives into some really interesting details before the quiz even starts.

So for example in the Solar Power quiz, it talks about how, of course,

all plants and animals are kind of connected with the sun, as far as their power goes, if you will,

but also how things like windmills depend on the sun,

as the wind fundamentally results from uneven heating of the Earth's surface.

Which I think is cool!

So then when you start the actual quiz, what's great is that it gives you all the information

that you really need to find the answer, and if you need to cheat you can just view the

solution, then go back and figure out how you would have gotten there in the first place.

And the first 200 people that sign up at brilliant.org/scishowspace

will not only be supporting our show, but will get 20% off an annual subscription.

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