Astrobiologist Answers Mars Questions

I'm Erika DeBenedictis,

a space scientist and astrobiologist.

I'm here today to answer your questions from the internet.

This is Mars Support.

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Secondfret asks,

Why is Mars red if not for the devil's light?

Explain that, science.

Mars is red for the really simple reason

that it's basically rusty.

So it has metals that make it look red.

It's not because of the devil's light,

nor is it because it's too hot.

Sometimes I've heard that.

People think Mars is red

because it's literally boiling or something like that.

Mars is cold and rusty, and that's why it looks red.

BigBootyBear asks,

Why did Elon Musk say,

'You can only depart to Mars once every two years?'

Mars and Earth both orbit the sun,

and that means that they're different distances apart

from one another at different times.

So here's Earth and here's Mars.

Earth orbits close to the sun pretty quickly.

Mars is farther away and it orbits the sun more slowly

because it has more distance to go.

And that's why a Mars year is two Earth years.

It takes Mars twice as long to get

all the way around the sun relative to Earth.

So you want to go between Earth and Mars

when they're closest together rather than when

Earth and Mars are on opposite sides of the sun.

Fundamentally, that difference in the length of the year

is where this idea of launch windows comes from.

TimothyDooner asks,

How realistic were the crop growing scenes

in 'The Martian?'

The Martian is such a good movie.

It was also a great book. I really like The Martian.

And in general, with just a couple exceptions,

both a fun and pretty realistic depiction

of what it might be like

to be trapped unexpectedly on Mars.

There's a famous scene where the main character realizes

that maybe he could grow potatoes to keep himself alive

and wait for rescue.

And so he mixes Mars regolith, the dirt,

with his own poop to fertilize it and he grows potatoes.

It's like very close to correct,

with one big problem.

At the time that The Martian, the book was written,

we didn't know about the toxin

that is in Mars dirt called perchlorate,

chemically really similar to bleach,

which you probably have in your house

because it kills things.

Like you use it to sterilize stuff.

Had he eaten those potatoes,

he would have died because it would have killed his thyroid.

It's ever so slightly wrong.

Carla Bitcoin asks,

How long would it take to terraform Mars?

Terraforming refers to this idea

that we might be able to take somewhere else

in the universe,

some other planet and make it more like earth,

gentler conditions, more amenable to supporting life.

A bunch of changes in new technology mean that big parts

of terraforming Mars might happen way faster

than you might expect.

Mars might be green in our lifetime,

so it could be covered with a complex ecosystem

of mostly plant life doing photosynthesis,

making oxygen and evolving.

RussianRouletteTime asks,

Any scientific inaccuracies in 'The Martian?'

Maybe one nitpick.

There's a scene where there's a big storm

that like causes a rocket to like vibrate

because of the wind.

That's not a thing.

Mars has really, really low pressure.

Although the wind speeds can be very high,

the air is just so thin that it doesn't pack a punch.

Bertha Coombs asks, Question for literal rocket scientists.

How long is the trip to Mars?

And how will we ever have enough energy fuel

to get people back to Earth?

This is a great question,

and the challenge of sending people to Mars

and bringing them back, that second part is so hard.

That is the reason why we haven't gone to Mars.

We barely have the technology to bring people back.

Getting there in the very best case scenario

takes six months.

Consider that when you go to Mars,

you get to launch from Earth with fresh humans

who are perfectly healthy.

You get to launch with a rocket that you got to tune up

with all of your equipment.

You get to fuel it with rocket fuel that you made

with all of our wonderful industry we have on earth.

When you launch from Mars, you have none of that.

You have people who might be less healthy.

You have a rocket that has now been reused once

with very few tools to fix it.

And the hardest part is the fuel.

It's very hard to either bring enough rocket fuel to Mars

to come back or to make it on site.

The crux of the challenge is how to enable that return trip,

which is so much harder than getting there.

Bastilam asks, Why are there mountains on Mars

that are much higher than the highest mountains

on other planets in the solar system?

Mars does have really tall mountains.

Famously, it has a mountain called Olympus Mons,

which is this really big shield volcano,

more than twice as tall as Everest on Earth.

There's a combination of reasons.

One reason is that unlike on Earth

where we have tectonic plates,

so all the continents are kind of floating

on top of this magma soup.

And that means that when you have a volcano,

the spot that it erupts will move.

That's why Hawaii is a chain that's one volcano

that kept erupting and made this chain.

On Mars, that wouldn't happen.

There aren't tectonic plates,

and so that volcano would just stay in the same spot

and keep erupting

and keep getting taller and taller and taller.

And on top of that, because Mars has somewhat less gravity,

you can like stack rocks kind of higher.

And so together, Mars ends up with really tall mountains.

MakiejFran93290 says,

Does Mars have seasons?

Yes, Mars has seasons.

It also has different locations on the planet

that have different climates, same as Earth.

In the middle of the day at the equator during summer,

the temperature could be 50 degrees Fahrenheit.

So a little chilly, but you just need a jacket.

Like it's not that cold.

But at night, things cool off really fast.

It could get down to negative 100 Fahrenheit.

It gets even colder during the winter.

On the edge of the ice cap,

it can get down to negative 200 Fahrenheit.

Corruptboomerang asks,

Why is everyone obsessed with colonizing Mars?

In a word, curiosity.

Humans are explorers.

We like to push the limits of what's possible

and learn about the world we live in.

Of places in our solar system,

Mars is in many ways the most intriguing target.

It's a place that a long time ago looked like Earth.

It has all the essentials that are needed for life.

Today, it's very hostile,

but perhaps with technology,

we could make it a really nice place to live.

Manria4 asks, What happened to that water on Mars?

Are we gonna do anything with that or what?

It's actually a common misconception

that Mars doesn't have water at all.

Mars has a ton of water.

It's just locked up as ice just beneath the surface.

So most of the whole northern hemisphere

of Mars is permafrost,

meaning it has like a really thin layer of dirt,

dust that makes it look like a desert.

But if you scrape down,

and one of the rovers did this,

if you scrape down just a tiny bit,

there's ice just below the surface.

BenHansen00 asks,

What kind of batteries do the Mars rovers use?

That's what I want to power my cell phone for 13 years.

Christmas gift ideas.

All of the modern Mars rovers actually use

lithium ion batteries just like your phone.

The difference is they have like a built-in solar panel

that they use every day to recharge.

The solar panels can last actually

way longer than NASA thought they would.

So famously, Spirit and Opportunity

were originally scheduled

to have like 90-day missions

because NASA thought that their solar panels

would fail after 90 days.

The thought was they would like basically

get covered with dust and they would stop working.

And instead, it turns out that the dust would settle

on the solar panels,

but sometimes it would also get cleaned off

of the solar panels.

And so instead of lasting three months,

these rovers lasted years,

and NASA had to appropriate like more funding

to fund scientists to like run these rovers

for years longer than they thought they would work.

Westonbdev asks,

Wait, how are humans going to breathe on Mars?

Has anyone considered this NASA?

All caps.

Yes, this is a big area of research.

NASA is on it, and there's broadly two options.

Mars actually does have an atmosphere.

It's almost entirely carbon dioxide,

and it's super thin,

so it's like 1% of the density of Earth's atmosphere.

Carbon dioxide, so there's oxygen in there.

And also even as a solid, it has dry ice,

which is carbon dioxide.

Mars also actually has a lot of water.

It has tons of ice that's just beneath the surface.

It's permafrost.

Water also, H2O, oxygen.

You can take either of these plentiful resources

and get the oxygen out.

NASA actually demonstrated on Mars a technology

called MOXIE that takes the carbon dioxide, splits it,

and gets the oxygen out of it.

And that is the current idea

for how the first humans on Mars will breathe.

Another option is to do it the old-fashioned way

with plants.

So plants breathe oxygen into the atmosphere

as they do photosynthesis,

and that oxygen comes from water

to make breathable air on Mars.

Vection says, 12 midnight, body, 'Go to sleep.'

Brain, 'I wonder how much I weigh on Mars.'

Mars is a little bit smaller than Earth,

and that means it has less gravity.

You weigh about 40% of how much you weigh on Earth.

You could jump like really high,

but you still have the same mass.

If you were to like go

and tackle someone by running really fast

and slamming into them,

you still have the same amount of energy

that you're knocking into them with,

even though the gravity is less.

Pestets1324 asks,

How fast would you die on Mars without a spaceship?

If you find yourself outside on Mars,

you're in a lot of trouble.

You probably could survive very brief exposure.

You won't be able to breathe,

which is sort of your first problem.

And in under a minute,

you're gonna probably go unconscious.

Mars is also far colder than you could tolerate

for a long period of time.

There are other things too on Mars that would kill you,

but over a much longer timeframe.

Mars has quite a lot of radiation, so it has UV radiation.

The dirt on Mars is literally toxic.

In general, if you're on Mars,

you do today need a spaceship or a habitat of some kind.

M3gummy asks, How old is Mars, this is important?

Earth and Mars are about the same age.

Our solar system formed

because it was this big glob of mass

that was kind of orbiting the sun, and over time,

the gravity of different parts of that mass

started coalescing into planets.

And so both Earth and Mars formed

into these circular globs of rock

about four and a half billion with a B years ago,

like a really long time ago.

Four billion years ago,

they actually probably looked really similar.

They both had liquid water,

so they were both these beautiful, like water-filled worlds

with rivers that carved canals into the surface.

Cut-Unique asks,

If, billions of years ago,

Mars really did have the necessary conditions

to support life,

why haven't they found any actual evidence of life?

The simplest answer is that

there wasn't ever any life there, but that's not fun.

We are still looking for evidence of life

despite the fact that we still haven't found anything

that's like obviously a smoking gun.

So far, what we know is that Mars

is like not obviously covered with plants.

We also know that there's not like obvious fossils

or anything that we found, although again,

it's a really big planet

and we've only had rovers

sort of spot check just a couple spots.

One sign of life that we've looked for

is basically oil.

One of the ways that we know

that there were dinosaurs 200 million years ago

is that the bodies of carbon-based life,

both the dinosaurs and plants that lived then,

have turned into oil today

because they got compacted and pressurized.

The hydrocarbons are themselves evidence

of ancient carbon-based life.

Mars basically doesn't have oil,

and it was a huge news story

when people found like the tiniest,

tiniest trace amounts of hydrocarbons.

So again, it's like exactly in this tantalizing place.

The signs are pointing to probably not,

and yet we're looking for like the tiniest indications

and like maybe finding some evidence of certain types

of chemistries that could have been produced by life.

But I think my favorite hypothesis is that

Mars maybe did used to have life,

and today it's no longer growing.

Mars is just too extreme,

but it could be that it's hibernating, it's locked up,

either trapped in the ice or maybe dried out, desiccated.

If only we went to Mars and we warmed it up,

we made it possible for there to be liquid water,

perhaps we would be able to revive life

that once lived on the surface of Mars.

That style of experiment, that style of search for life

is what we use on earth in really extreme environments.

So when people go to Antarctica,

often they don't look directly to see if things are growing,

and instead they take a sample

and see if when put into less harsh conditions,

something grows and sort of becomes obviously alive.

Workbot1 asks, Have we learned anything new from Mars

that we didn't already know

before landing there with a rover?

Scientists, before we sent rovers,

figured out a lot of stuff just from pictures of Mars.

The fact that there used to be some sort of liquid

on Mars is like obvious from just orbit.

You can do like a satellite image and just like look

and you can see river deltas.

Like it's really obvious

that some liquid was there carving its way on the surface.

That conclusion was then followed up on

with supporting evidence of many different sorts

by actually sending a rover down to look at the chemistry

of the rocks that very conclusively point to the fact

that liquid water was once there.

But there are some things that you can't see from space.

The existence of perchlorate in the dirt

on Mars was something

we had no idea about until like the 2010s

when rovers went there,

and we only know that this is a huge problem

we need to solve when we go to Mars because we had rovers.

Eric Jorem asks, How are people going to build a base

on Mars when they can barely stand

after they are pulled out of a space capsule

after nine months?

Being in space is not good for your body.

If you spend a long time in space,

you become frail and sort of weak very quickly.

It's so relaxing to your body,

your body doesn't have to hold itself up

that your muscles start wasting away

and your bone density goes down.

We know this because astronauts on the ISS have been under

a lot of medical observation

so that we can try to figure out what to do to fix it.

Folks have figured out ways

of exercising astronauts in microgravity

that help a lot toward maintaining muscle mass

and bone density.

So people on the ISS spend like two hours a day

exercising every day.

Konstructivizm asks,

What type of material is the surface

of Mars primarily made of?

So unfortunately, we have never brought samples

of Mars dirt back to earth,

which I would love because then we could run lots of tests

and know exactly what's in it.

Instead, we have data from rovers of what the regolith

or Mars dirt is like in a couple different spots.

So what scientists use to study Mars dirt

is we use what's called regolith simulants,

and they mimic like the mineral composition

of the dirt at the Perseverance landing site,

that's one rover, or the Curiosity landing site,

this is another rover.

And this is obviously not real Mars dirt

because if it was, it'd be under armed guard.

I mean, this would be incredibly valuable.

What this actually is is someone went out on earth

and found some rocks that have similar mineral composition

to what the rovers saw on Mars.

They ground them up to the right size

and they send it to us in a little tube.

There's a couple big differences

between Mars dirt and earth dirt.

One is there's a toxin in Mars dirt called perchlorate.

It will kill you.

The other really big difference

is that nothing has ever lived and died in this dirt.

It's literally just ground up minerals.

That is a problem for things like agriculture.

Most plants require that there's all sorts of things

in the soil.

Soil has a whole microbiome.

There's bacteria in the dirt

that create nitrogen to feed the plants.

There's degrading organic matter from things

that have grown before, and Mars dirt has none of that.

It's basically sterile rock dust.

Letsandrea asks,

What would a habitat look like on Mars?

I'll maybe describe two possible habitats.

The first is sort of the equivalent

of like an adobe building,

but on Mars that most makes use of the local resources,

which is important because you don't want to have

to schlep heavy stuff to Mars.

You could basically make these like dirt-covered huts

that protect you, the human inside,

from radiation by having really thick mud bricks.

As another option that is a little more high-tech,

maybe more aesthetic,

people are actually thinking about

using advanced materials to make greenhouses on Mars,

and I brought a sample of one

of the materials people are considering.

So this is Aerogel, this very light substance.

It's transparent and it's really good at blocking radiation.

And so people are thinking about creating greenhouses

that use this sort of material to protect

the people inside from radiation, insulate them,

and allow us to look outdoors.

All right, that's all the questions, thanks for watching.

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