- [Cory] What you're looking at
are tiny bits of rock and metal
under a device called an electron microprobe.
The samples came from a rooftop in Brooklyn
but they might have traveled quite a ways to get there.
Possibly from outer space.
We're at NASA trying to figure out
whether they really are tiny meteorites.
Because if so, they could help unlock secrets
you really wouldn't believe.
(soft music)
- So earlier this year we set out
to find a micrometeorite of our own.
We wandered around a roof with a powerful magnet.
We spent hours in front of a microscope.
We got advice from a Norwegian jazz guitarist
who also happens to be the world's
foremost micrometeorite hunter.
You know what, just watch the other video.
We'll put a link to it at the end.
Anyways, the end result was this image.
It's our best sample.
The one most likely to have come from space.
But, the image alone isn't conclusive.
We wanted to find out what it takes
to positively ID a meteorite.
And what scientist can learn from it.
So we headed to NASA's Johnson Space Center in Houston
where, well, we met this guy.
- You take a bee's head, right
You glue the bee's head to a carbon disk.
Just look at the bee's head, and kids love this, right.
You see the eyes and the hairs are all moving
around like this 'cause they hard jump
and they swirl around.
- [Cory] Mike Zolensky is a space scientist at Johnson.
He's walking us through the electron microprobe.
It uses a stream of electrons the way
a microscope uses photons.
Particles bounce off your sample and hit a sensor,
returning a wonderfully detailed image
of tiny rocks or anything else you put in there.
- I used to have a bee's head just for tours.
And believe me, adults love it too.
I mean, everyone loves looking at the bee's head.
- Oh, yeah, it's amazing.
Mike works within NASA's astromaterials research
and exploration science division.
It's a very nondescript building at Johnson
but inside is maybe the ultimate cabinet of curios.
Materials from the moon and Mars.
Dust from comets.
Flecks of asteroids.
Atoms from the sun.
We're interested in the 60 to 100 tons
of material from outer space that lands on Earth each day.
Most of it lands unnoticed but every now and again
a big meteor lights up the sky and experts like Mike,
mobilize to collect samples from it.
It all sounds pretty Indiana Jones-y.
- It's really fun, usually.
It's sometimes a gun and it's not fun, you know.
- [Cory] Does that happen?
- Yeah, sure, but it's okay.
It's a long story, long story.
- Mike's job is to wring every detail possible
out of the samples that cross his desk.
Some are big like these two that he showed us.
Samples that landed in Australia and Morocco.
But our samples are only a couple hundred micrometers wide.
We brought a few along with us.
Our best candidate, plus a few bonus options.
And one sample from our expert in Norway.
To the naked eye they're almost invisible.
In our microscope, you can start to see some shape
and texture but in the electron microprobe.
Wow.
We visited Houston to answer a simple question.
Did any of our samples actually come from space?
And to figure that out, we looked at two things.
The shape of the rocks and the chemical elements
present on their surface.
The electron microprobe can measure both.
We started with shape.
- [Mike] So here's one of the samples
that you found in, I guess Brooklyn, right?
- This was a rooftop in Brooklyn, yeah.
- Yeah, wow.
These are all spheres, so they definitely
were melted in the atmosphere.
- The idea is that as a tiny object speeds
through the air, it melts and globs into a little ball.
But that can happen to Earthly materials, too.
Like bits of industrial pollution.
- The question there is, is it extraterrestrial sample
or could it be from, say, a coal fired power plant?
- The material makeup of our samples were less encouraging.
IDing a meteorite often means finding elements
that are rare on Earth's surface but common in space.
Things like palladium, platinum, uranium.
But sample after sample, we saw very Earthly elements.
Iron, oxygen, silicon.
- So, this second particle again, we see the same pattern.
These little flattened crystals on the outside.
Which, again, are magnetite.
Over here are iron oxide.
But it's probably terrestrial contamination.
Our sample from Norway was much more exotic.
- These have these little dendritic,
like little fern shaped crystals
of something else on the outside.
- [Cory] Mike says that crystalline structure
is usually the mark of a voyage all the way
from space to the Earth's surface.
But what really tipped the scales?
The probe readout showed lots
of magnesium mixed with a little silica.
- That's telling us this is another mineral
called olivine which is the most common mineral
in the solar system, probably.
This is in almost every kind of meteorite
and micrometeorite I can think of.
So this is almost pretty much nails
this as being a micrometeorite.
- Olivine is quite common here on Earth
but it's largely found inside the planet.
Olivine can reach the surface via volcanic activity
but it's presence still makes you take a sample like this
seriously and after 30 years in the business,
Mike can spot olivine from a mile away.
- It's so common, I just recognize it instantly now,
you know, it's like an old friend.
Really old friend, four and a half billion years,
that's a really old friend, right?
- So, where does that leave our samples?
What came of all those hours spent searching?
Not much.
Mike says you'd have to look inside the samples
to be sure but nothing seemed conclusive.
We basically found magnetic dirt.
Hunting down tiny rocks from space
is laborious and frustrating.
But for NASA each verified sample
truly is a diamond in the rough.
Because if you know what to look for
and you find it, the whole galaxy opens up to you.
- [Mike] We've found meteorites like this
that contain liquid water droplets in salt.
So those were our first samples of extraterrestrial oceans.
Where were those environments, we don't know.
We need to find that out but now we're learning about,
you know, what kind, what were the first steps
towards, perhaps, life.
First steps towards organized cells,
those were present perhaps in these meteorites.
- [Cory] Other samples hold clues that could change
our understanding of the solar system.
Samples like this one.
- So this is a rock that is from an asteroid
that is from the inner solar system
and heated up, melted, it contains,
the composition suggests it formed
in the inner solar system but it contains
bits of rock from the outer solar system.
And the question is, how'd those get mixed together?
- [Cory] One theory, the planets weren't
always in the position they are now.
- So the models have Venus and Neptune swapping places.
Saturn and Jupiter moved in pretty far and stopped,
then moved back out again and there's
a chance that we can date that process
by studying this rock and other rocks like it.
- NASA has other samples still
of very old cosmic dust.
Little motes of material that can teach us
about the earliest days of the solar system.
Some samples arrived via comets
which contain dust from the farthest edges
of the solar system and dump some of it
along the Earth's path.
And once in a while, even rarer samples turn up.
Dust from outside the solar system.
From before it.
- [Mike] The galaxy is turning and we're part of that.
And as the galaxy spins around like a pinwheel
there's a rain shower of interstellar dust
passing through our solar system.
They're usually really tiny
and they're pretty rare but that happens.
- Space is a paradox.
It's vast and almost completely empty.
Yet at the same time it's teeming with material.
We can study some things with telescopes and probes.
Other times, we're stuck with models.
Mathematical guesses that tell us,
this is probably happening somewhere, out there.
Except sometimes, if we're lucky,
actual physical evidence from out there,
happens to land at our feet.
And then one little speck like this one
can change everything.
- You can find grains that prove
that supernovas happen the way we think they do or don't.
There are grains from Wolf-Rayet stars
and red giant stars that tell us about
the process of star formation and death.
It's pretty amazing that you can test all those,
apparently, strange wacky theories us physicists have
by looking at little microscopic grains of meteorites,
but it's true.
- Hey everyone, if you wanna find out
how to collect your own micrometeorites
be sure to check out part one down here.
And as always, thanks for watching.