To understand how something is intangible
as thin air protects us
you need to find a meteorite
that has survived its fall to earth.
Meteorites are rare,
so you need to go to great lengths to track one down.
Dr. Phil Bland
is a planetary scientist on just such a mission,
leading an expedition out onto the barren Nullarbor Plain, Western Australia.
Three days drive from the nearest town.
The Nullarbor is vast, about the size
of Great Britain, but it's as flat as a pancake.
So it's the ideal hunting ground for meteorites.
Nothing has changed here for millions of years,
allowing meteorites to accumulate undisturbed.
The team head off to scour the desert
like a police search team.
The Nullarbor,
a good place to look for meteorites because it's a limestone plateau.
So don't meteorites stand out pretty well against the limestone
and there's not much vegetation.
So you can see the ground quite clearly
Meteorites are quite dark.
And when they've been out here for a while,
they were just a little bit they have chunks of metal in them.
And so you get a kind of a dark, rusty texture.
After 3 hours of searching in temperatures
above 45 degrees, the team haven't had much luck.
I think I got one.
That's pretty good.
That's lovely. Oh, that's a good one.
Looks like it's got some nice fusion crust.
Yeah, that's lovely.
The glassy stuff that melts when it comes in
Must have broken up in the atmosphere before it hit the earth.
Yeah, You can tell this is a meteorite because it's quite heavy.
It's quite dark, it's got little rusty patches, and it's got this smooth surface
from when it came through the atmosphere.
This little chunk of rock would once have been something much more substantial.
Before it hit the top of the atmosphere.
Something like this might have been part of an object
the size of a washing machine or a small car, but
a car made of solid rock and and that's punched into the atmosphere,
surfaces melted and been stripped off and then re melted and stripped off
and gradually whittled down to small little chunks like this.
An object like this will hit the top of the atmosphere at about
just under 20 kilometers a second.
Now, the bulk of our atmosphere,
almost all of it
is within 60 miles of the surface.
So if that didn't slow down,
it would translate the whole atmosphere in 3 seconds.
But it does slow down.
The atmosphere acts like a brake on it and strips material off and gradually
it'll slow down to the speed as if you just dropped it off a tall building
without Earth's atmosphere, constantly
protecting the planet from such projectiles, life on earth
would suffer a regular bombardment from objects in space.
What that tells us about the atmosphere is that it's an effective protection
for for, you know, us and other
life on earth.