Mars is in the spotlight now, as both SpaceX and NASA are preparing their long range plans
to send humans to the Red Planet.
But Mars is an inhospitable environment, especially because of its tenuous and poisonous atmosphere
of carbon dioxide.
Did Mars have a better atmosphere in the past?
How did it get destroyed, and what can we do to replenish it to make the planet more
habitable in the future?
If you were to travel to the surface of Mars right now, without a proper spacesuit, your
life would become immediately, uh, unpleasant.
With a dramatically lower atmospheric pressure, all the air in your lungs would come rushing
out.
And without the oxygen in your blood stream, you’d pass out within seconds, and asphyxiate
within a couple of minutes.
Mars, sucks.
And the biggest reason is that Mars is so hostile is because of its terrible atmosphere.
Here on Earth, you’re experiencing a column of air, pressing down on you, enabling all
that breathing that you seem to like to do.
The atmosphere on Mars, on the other hand, is only 1% the pressure we have here on Earth.
Furthermore, it’s made almost entirely of carbon dioxide, which I’m sure you know
is poisonous to breathe.
The lack of a thick atmosphere means that Mars is cold, so cold all the water on the
planet is locked up in eternal polar ice caps.
So cold that carbon dioxide freezes out of the atmosphere and falls as snow in the north
pole.
Just in case you weren’t aware, temperatures need to be -78.5 degrees C for carbon dioxide
to freeze.
Was Mars always this way?
What changed to make the planet so terrible, and what could we do to bring it back?
In the early Solar System, Mars was much more like Earth, with its own planetary magnetosphere.
This was present for the first 400 million years or so of Mars’ history.
Then, about 4.2 billion years ago, this Martian magnetosphere shut off, leaving the planet
without any protection from the Sun’s radiation and solar wind.
Over the course of 500 million years, Mars changed from a warm, wet environment to the
frozen, airless desert we know today.
In early 2017, planetary scientists working with NASA’s Mars Atmosphere and Volatile
Evolution spacecraft, or MAVEN, released a research paper explaining in gruesome detail
exactly what happened to the Martian atmosphere.
And the blame comes, of course, from the Sun and its constantly blowing, ever present,
why won’t you give us a break, solar wind.
The solar wind, of course, is the constant stream of particles blasting off the Sun.
The Earth is protected, thanks to our ever present magnetosphere, but Mars wasn’t so
lucky.
According to the researchers, most of the gas that was ever present in the Martian atmosphere
was just blown away into space.
Mars didn’t have a magnetosphere, and it has much less mass and gravity, so it was
unable to hold onto the atmospheric particles.
The atmosphere of Mars is gone.
In fact, the early Sun was even worse, with much more powerful ultraviolet radiation and
intense solar winds.
If life did ever form on Mars, back in the early Solar System, it would have needed to
work fast, with a very short time when the planet wasn’t a freezing cold, airless desert.
There might still be pockets of life, hidden beneath the surface of Mars, but the party’s
over.
So how did researchers figure this out?
They used MAVEN to measure the amount of two different isotopes of argon gas.
Argon doesn’t react, so it can’t be trapped in rocks the way other elements can.
One of these isotopes is lighter and escaped into space more easily, so they measured the
ratio of the two isotopes in both the surface of Mars and its atmosphere to figure how quickly
it was lost into space.
And from there they could calculate how quickly the other gasses were blown away too.
As soon as anyone learns how much the atmosphere of Mars sucks, they want to fix it.
And it might actually be possible.
I’ll talk about some ideas, but first I’d like to thank:
Skydiving Storm Trooper Robert Eidson
Rod Cortright
And the rest of our 810 patrons for their generous support.
If you love what we’re doing and want to get in on the action, head over to patreon.com/universetoday.
It turns out that the easiest solution to restoring the atmosphere of Mars is to destroy
the Sun.
Without the Sun, there’d be no solar wind.
Okay fine, maybe that’s a little bit overkill, but you could block the Sun’s solar wind.
We did a whole episode on creating artificial magnetospheres a few episodes ago, and one
cool idea was recently presented by Dr. Jim Green, the Director of NASA’s Planetary
Science Division.
This idea would position an electromagnetic shield at the Sun-Mars L1 Lagrange point.
This shield would block the solar wind coming from the Sun, protecting Mars in its wake.
This would have the advantage of protecting Martian astronauts from deadly solar radiation,
but it would also protect and restore Mars itself.
Even though Mars has had billions of years to lose its atmosphere, it still has something,
however tenuous.
That’s because volcanic outgassing from the planet’s interior balances out the atmosphere
lost to the solar wind.
Without the solar wind whisking away the atmosphere, this volcanic outgassing would thicken and
warm the atmosphere by an average of about 4 degrees Celsius.
That doesn’t sound like much, but it’s enough to melt the northern carbon dioxide
polar ice cap on Mars, leading to an even stronger greenhouse effect.
This would warm the planet enough to melt the water ice in the polar caps, creating
oceans on the surface of Mars.
Not like it had in the past, but still, oceans.
Within a couple of generations, Mars would be a dramatically different world.
Much more earthlike and ready for exploration.
A thicker atmosphere would provide a range of benefits, including allowing larger payloads
to be sent to Mars and aerobraked using the Martian atmosphere.
It would provide increased shielding against galactic cosmic radiation, which wouldn’t
be stopped by the L1 shield.
It would provide a thicker atmosphere for oxygen extraction, and allow open air greenhouses
for farming food.
Future colonists would be able to go outside on the surface of Mars without a pressure
suit, just a gas mask to provide breathable air and prevent carbon dioxide poisoning.
But obviously we’ll want to go further, we’ll want to make the air actually breathable.
According to Robert Zubrin, the founder of the Mars Society, this is a long term goal
that should be achievable.
In that thicker atmosphere of carbon dioxide, we could bring in plants that would do the
same job they do here on Earth; taking in CO2 and releasing oxygen.
As the atmosphere gets thicker and more Earthlike, you could bring in insects and other tough
animals to keep the ecosystem going.
It might take thousands of years, but we should eventually be able to make Mars a place that
humans can walk outside, without a spacesuit and breathe normally.
It’s pretty mind boggling.
The fact that Mars lost its atmosphere so long ago is a tragedy.
But it does look like there’s a way we could stop the atmospheric loss and even rebuild
it, making Mars a reasonably habitable world again.
Being able to grow plants, to walk outside without a pressure suit, to be able to breathe
the air on an alien world.
It’s worthy goal for humanity, I think.
Of course, to make Mars more habitable, we’ll need to make it less habitable for any lifeforms
currently tucked away in corners on the planet.
What do you think, is it okay for us to modify Mars to suit our needs, potentially destroying
its existing biosphere?
Let me know your thoughts in the comments.
Time for your playlist, all about the atmosphere of Mars and ideas about terraforming the Red
Planet.
First up, a really cool video from NASA that shows why the Martian atmosphere is bleeding
away.
Another video from NASA about one of the mechanisms that contributed to Martian atmosphere loss,
and more information about how the solar winds strip the air off Mars.
A talk at the SETI Institute about the discoveries made about the Martian atmosphere.
Finally, a longer lecture from NASA about MAVEN’s observations about the atmosphere
on Mars.