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This episode is sponsored by Squarespace.
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[♪ INTRO]
Finding a new exoplanet used to be a really big deal all on its own.
I remember these days!
I was alive when we found the first exoplanet!
But now that we've found thousands of planets orbiting other stars,
and astronomers don't just want to know that a planet exists, they want to know what it's like.
New work published last week in the journal Science shows one creative way to answer that question.
And the work reveals that, throughout the galaxy, planets seem to be made up of rock
that's a lot like the rock you might pick up in your backyard.
Understanding the composition of exoplanets is tricky business,
because we can't just like, fly over and bring a piece back to the lab
and do a bunch of chemistry on it.
In some cases, you can learn a lot by watching how light from a planet's star gets altered
as it passes through the planet's atmosphere.
But that won't get you anywhere with a planet that doesn't have an atmosphere.
And sometimes scientists care more about what's under the surface than what's floating above it.
For decades, there's been basically no solution for these problems,
but this new research came up with an unusual solution to the problem:
scope out worlds that are in the process of being destroyed.
The work focuses on six white dwarf stars,
the burned-out cores left behind when stars like our Sun reach the end of their lives.
White dwarfs are extremely dense, and their powerful gravity can shred any asteroids or
planetary fragments that wander too close.
As that material falls onto the star, it pollutes the star's outer layers with new elements.
Astronomers can see the signatures of those elements in the star's light.
In this study, researchers scoured past observations of nearby white dwarfs
in search of the six most common elements in Earth's crust:
iron, oxygen, silicon, magnesium, calcium, and aluminum.
And they found them.
But their most important finding was that there wasn't just iron and oxygen in these rocks,
there was iron oxide, better known as rust.
Iron oxide is common in rocks from our solar system, but it only forms under the right conditions,
such as in places with tectonic activity.
Finding it in these far-flung locations means that it's probably common
for rocky planets to have tectonic plates, just like Earth.
And the fact that this iron oxide exists also suggests
that these planets could have magnetic fields and atmospheres just like us.
Basically, the study implies that these far-off worlds are pretty similar to Earth and its rocky neighbors,
which could make it a whole lot easier to understand the nature of exoplanets.
Also, watching a planet get destroyed is a pretty fun way to do science.
I hope there wasn't anybody, like, living their best life there.
They certainly aren't anymore.
Last week, we also got some good news about NASA's ability to explore closer to home.
As part of its Artemis project to return astronauts to the Moon, the agency revealed a new spacesuit
designed to better meet astronauts' needs wherever they're working.
The most important change is in sizing.
NASA's current suit can trace its origins to the ones worn by Apollo astronauts on the Moon.
Astronauts who, of course, were all men.
As you might expect, this has created problems,
like in early 2019, when NASA was forced to cancel the first planned all-woman spacewalk
because they couldn't come up with two working suits that fit them.
That historic walk finally happened last week,
but the whole affair highlighted the ongoing inequity faced by female astronauts.
NASA's new design solves that problem, at least, when it comes to spacesuits.
With this new program, each astronaut will have their entire body 3D-scanned.
And with that data in hand, engineers can match the astronaut with the most comfortable suit.
The spacesuits are designed to fit nearly all body types, women, and men.
They're also easier to put on and more flexible,
which should make it easier for future Moonwalkers to carry out their tasks on the surface.
There's still lots of work left to do, though, and NASA expects it will be about two years
before an astronaut on the International Space Station takes one for the first test-drive.
But when it's ready, this new suit could support astronauts for decades of future exploration.
So good thing it also looks pretty cool.
Finally, we wanted to share some happy news about NASA's Mars InSight mission,
which has been working to understand the interior of Mars since last year.
One of Insight's key instruments is the Heat Flow and Physical Properties Package
or HP^3, which was provided by the German Aerospace Center.
HP^3 is designed to burrow several meters underground and make temperature measurements
that will help scientists calculate how quickly Mars is losing heat.
Its centerpiece is what's called the “mole,” which is sometimes described as a “self-hammering nail.”
It just kind of slams itself deeper and deeper into the ground,
dragging a wire behind it to relay data back to InSight.
But back in March, the mole suddenly stopped making progress
after traveling only about 35 centimeters below the surface.
Now, seven months later, engineers finally got it moving again!
The problem turned out to be a lack of friction.
The mole relies on friction with the surrounding material to drag itself further down,
but the upper layer of the Martian surface is crustier than scientists expected,
so the mole had trouble grabbing hold.
NASA's solution was pretty clever, they used InSight's robotic arm
to press the mole against the side of the borehole, giving it the friction it needed to move forward.
So far, it's only gone a couple of extra centimeters,
but that is a lot more than the nothing they were getting before.
So score one for engineering a solution from a hundred million kilometers away.
From stealing a peek at dying worlds to 3D-scanning astronauts and lending a hand to a self-hammering nail,
this was totally a week for out-of-the-box thinking.
Making it up as you go is part of what makes exploration so cool.
Engineering creative solutions in space is one thing.
But that kind of creativity can also go a long way here on Earth.
And say you had a great idea, like if you wanted to start a campaign to plant trees
and let the world know about it.
You might want to create a website.
Squarespace is one place to start.
It's got powerful blogging tools, so you can easily share stories, photos, videos, and updates.
You can even schedule your posts to make your content go out when you're ready.
The blogging platform also supports a sharing button
that your visitors can use to share content on Facebook, Twitter, Reddit, and more.
You can also reach people in their inboxes by setting up a Squarespace email campaigns.
It's easy to use the Squarespace platform to unify your brand voice,
from your homepage to your emails.
And you can get a free trial.
When you're ready to get started, head over to squarespace.com/SPACE
and use the code “space” to save 10% off your first purchase of a website or domain.
[♪ OUTRO]
コツ：単語をクリックしてすぐ意味を調べられます！

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The Surprising Secrets of Destroyed Exoplanets | SciShow News

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林宜悉 2019 年 11 月 25 日 に公開

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