We’re kinda destroying our lovely Earth,
so can’t we just go to the Moon?
TERRAFORM!
Yeah, that’s probably not the best option…
Hey guys!
Moon-loving Amy with you on DNews today!
We got a great question on Twitter from @atul05kumar.
He asked why our Moon doesn't have an atmosphere
and what would happen if we created one?
When we think of a body having an atmosphere,
we typically think of one like Earth’s:
a nice, cozy envelope of life-giving gases
at pressure that keeps us alive and well.
To keep an atmosphere like that, or any atmosphere,
a planet needs a few things.
It needs to be big enough to have enough gravity
to hold on to that atmosphere, and some kind
of protection from the solar wind so it doesn’t
get completely eroded away.
Mars is a great example.
The planet lost its past thicker atmosphere
because it’s gravity is too weak to hold
on to the gasses and it doesn’t have a magnetic
field.
Solar particles have ripped the gases away,
leaving the planet with the tenuous layer
of carbon dioxide it has today.
Our Moon is smaller than Mars and has even
lower gravity, and it’s geologically inactive
so has nothing to produce a magnetic field
— basically a recipe for having no atmosphere…right?
Well, the Moon actually does have an atmosphere!
It’s just super rarified, so much so that
the engineers who designed the Apollo lunar
module were able to completely ignore it (not
to mention they didn’t know it was a thing
at the time but it all worked out).
It’s barely considered an atmosphere; properly
speaking, it’s called an exosphere.
It’s some 100 trillion times less dense
than Earth’s atmosphere at sea level.
That’s about the equivalent density as the
area in space where International Space Station
orbits.
But still, it’s there!
And interestingly, the solar wind that destroys
atmosphere is also one of the factors contributing
to the Moon’s.
The Moon is constantly blasted with a stream
of particles from the Sun that act as an abrasive,
knocking sodium and potassium atoms off the
surface to populate the exosphere.
There is also gas constantly being released
from the Moon’s interior; the radioactive
decay of potassium atoms leads to exospheric
argon and helium.
More material is also released after impacts
of comets and meteoroids.
There are still a lot of unknowns about the
Moon’s atmosphere, but with the discovery
of water molecules trapped in the regolith
(aka moon dust), scientists suspect the exosphere
might play a role in a potentially dynamic
lunar water cycle, moving molecules between
the polar regions and the lower latitudes.
As for creating an atmosphere on the Moon…
well that one’s a little trickier.
The same conditions that have contributed
to the Moon having no atmosphere mean it’s
unlikely to retain one we create for very
long.
But could we even create one?
It would be really hard.
Terraforming the Moon — not just building
a colony or a bubble to live in but changing
the Moon so it can support human life — would
mean adding volatiles like hydrogen, nitrogen,
and carbon, and the only place to get those
elements in large enough quantities is in
the distant regions of the solar system in
the form of comets.
We’d have to capture these comets and smash
them into the Moon, allowing the frozen material
to sublimate and populate the atmosphere.
This would potentially liberate water in the
lunar regolith at the same time, yielding
natural bodies of water.
Ideally, the momentum from these impacts would
also get the Moon spinning faster so humans
living there could have a more natural day-night
cycle.
But this is massively complicated and way
out of our current technological capabilities!
So it’s unlikely to be something we’ll
see anytime soon, and by anytime soon I mean
any century soon.
But that doesn’t mean there aren’t reasons
for us to keep researching the Moon.
Because the lessons learned from Apollo — including
the first ever indication of what makes up
the Moon’s atmosphere — really taught
us that there’s a lot more to learn.
If you want to learn more about NASA’s Moon
landing on the go, check out the show When
We Left Earth.
You can get it now on the Discovery Go app.
Check your app store or the link below in
the description to find out more!
And speaking of going to the Moon, the Moon’s
non-atmosphere helps explain why there’s
no flame when the Apollo lunar modules left
the surface.
I explain the whole story over on my channel,
Vintage Space.
And also, why do we only have one moon?
Well, we made a video about that, here.
So what other Moon mysteries - or just mysteries!
- keep you guys up at night?
Let us know in the comments below, be sure
to like this video, and don't forget to subscribe
for new episodes of DNews every single day.
