[ intro ]
2020 marks two decades of people living and working aboard
the International Space Station.
And in those twenty years, they’ve been busy!
The scientists aboard the ISS have done
thousands of experiments. And some of the things they’re studying up there —
well, they’re not what you might picture astronauts thinking about.
Because they’re not just studying stars and galaxies:
They’re also making fireballs, solving mysteries about lightning,
and even growing parts that could power the next generation of computers.
Let’s start with fireballs. Because I know what you’re thinking:
Fire in an enclosed area that’s whipping around the Earth at almost eight kilometers per second…
is a bad idea.
And normally, it is! But if we’re serious about preventing fires in space,
we need to know what fire acts like in microgravity —
because it’s pretty unique.
On the ground, a fire gets most of its new oxygen from convection.
That’s where warmer, lighter air rises in the middle of a flame
and makes a gap for cool air to flow in from the sides.
But in orbit, there’s no concept of weight, so warmer air isn’t lighter.
That means it doesn’t rise, so there’s no convection.
Instead, oxygen reaches the flames through diffusion,
where new gas slowly works its way from the outside of the flame ball to the center.
And yeah, I said “flame ball!” Because without the moving air from convection,
fires in space are also spherical.
We’ve known about all this for decades, thanks to various experiments.
But having a permanent lab in the ISS has let us learn how to apply this knowledge.
Since 2011, researchers on the Station have been working on the
Burning and Suppression of Solids investigation.
In it, researchers put a test material in the fireproof Microgravity Science Glovebox.
Then, they light it on fire,
let it burn, and eventually blast some fire suppressant into the box.
It’s simple, but it’s taught us a lot.
Like, these tests have shown that without convection,
heat doesn’t move away from materials as fast as it does on Earth.
So some things can be more flammable in space —
including some cotton-based fabrics!
That’s the sort of thing we want to know as we’re planning what clothing
and equipment to bring on future missions.
So, by making a few carefully-controlled fires now,
we’re preventing surprise fires in the future.
Next, being in orbit also gives the ISS an unmatched view of pretty much everything,
including thunderstorms.
And that’s great, because even though thousands of storms happen every day,
there’s a lot we don’t know about them.
For instance, we’ve known for years that storms make gamma rays in what are called TGFs,
or terrestrial gamma-ray flashes.
Theoretically, we could use these flashes to make more robust weather predictions.
But first, we had to figure out where they actually came from.
And that didn’t happen until 2019, thanks to instruments on the Space
Station’s Atmosphere-Space Interactions Monitor.
It was added to the Station in 2018,
and it lets us study how lightning’s energy spreads through the upper atmosphere.
It’s also able to look at lightning and TGFs at the same time, which was new for us.
And that helped us figure out where these lights come from.
According to work presented at an international geophysics conference,
TGFs form in front of a lightning bolt.
Based on data from the Interactions Monitor,
the researchers concluded that as an electric field goes through the air,
it interacts with molecules in the atmosphere and causes them to shoot out a bunch of electrons.
And we see those electrons as gamma-ray flashes!
Now, the next step is to figure out if we really can use TGFs to better predict the weather.
But for now, just knowing more about where those lights come from has given us a big head start.
It will take time for research into fires and lightning to directly impact life on the ground.
But ISS experiments with crystals
could have a direct impact on how you’re able to watch this video.
A crystal is a solid with a regular, repeated arrangement of atoms.
And they’re useful in building all kinds of tech, including the chips used in semiconductors —
which are super common in electronics.
The trouble is, growing crystals is a delicate process.
Generally, it either involves letting a liquid freeze,
or letting solids suspended in a liquid build up on a surface.
And even something as simple as heat can mess that up.
Like, if one part of a liquid gets cooler than another,
it can start sinking and disrupt everything.
That’s convection at work again,
and it’s the opposite of how warmer, lighter air rises in flames.
In this case, it’s just cooler, denser liquid sinking.
And here, that sinking can lead to lumps and bumps in the crystal,
or it can make the atoms more neatly-arranged in one direction than another.
Right now, that means chips often have minor imperfections that slow the machine down.
But space research could help with that.
Researchers have been studying the crystals in semiconductors on the ISS since 2002,
as part of the SUBSA program.
The tests involve watching how crystals form
and change in microgravity with different temperatures, time limits, and more.
And they’ve shown us that crystals grow so much better up there.
Since there’s no sense of weight and no convection in orbit, crystals can grow perfectly uniformly.
And now, scientists think we can harness that information to build better chips on Earth.
Others are even imagining a whole new instrustry of chips grown in orbit
for the world’s best computers and instruments.
So, 20 years ago, we had high hopes for the International Space Station.
But having a permanent laboratory in orbit has deepened our understanding of the world
in ways probably no one could have predicted.
If you want to keep celebrating the Station’s twentieth anniversary with us, good news!
For our November pin of the month, we made ISS pins!
They’re shiny and lovely, and only available this month. Starting in December,
we’ll have a brand-new design.
If you want to get one for yourself, you can head over to DFTBA.comSciShow.
[ outro ]