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  • [ ♪ Intro ]

  • In 2015, New Horizons made its famous Pluto flyby,

  • but once it left Pluto, its mission wasn't over.

  • For the last few years, the spacecraft has been traveling toward an even more distant object

  • that's been frozen in time for billions of years.

  • It's an icy world called 2014 MU69.

  • The team has nicknamed it Ultima Thule, and while you're ringing in the New Year on January 1st,

  • New Horizons will finally fly by it.

  • Ultima Thule is a rock about the size of a city and is 6.6 billion kilometers away.

  • It's located in the Kuiper belt, way out past the orbit of Pluto.

  • And that makes it the most distant object a spacecraft has ever visited.

  • But you classical lit scholars out there already knew that because Ultima Thule means it's beyond the known world.

  • Way to be interdisciplinary, NASA!

  • Back in August, New Horizons sent NASA a grainy postcard with its first picture of Ultima Thule,

  • and since then, the probe has been hurtling toward its target at about 14 kilometers per second.

  • That's more than 50,000 kilometers per hour!

  • New Horizons is going so fast that it won't be able to slow down enough to orbit the object.

  • Instead, it will just make a flyby, like it did with Pluto.

  • But that doesn't mean it will be easy.

  • We don't understand Ultima Thule's orbit very well, so it's been hard to aim for,

  • and astronomers have had to track it constantly.

  • But since it's just a dim little speck in a sky full of stars, it's not easy to track, either.

  • We don't even know if it's a single object or two giant rocks orbiting really close together.

  • To make things more complicated,

  • New Horizons is also trying to get even closer to Ultima Thule than it did to Pluto.

  • If all goes well, it's planning to skim just 3,500 kilometers above the surface.

  • Which, at 14 kilometers per second, means there's virtually no room for error.

  • But it'll to be worth it.

  • Visiting Ultima Thule is like exploring an amazingly well preserved, 4-billion-year-old fossil.

  • It's an ancient rock that formed at the same time as our solar system.

  • And ever since then, it's been frozen solid at only a few dozen degrees Celsius above absolute zero.

  • So, in a way, visiting Ultima Thule is like going back in time.

  • We'll get to explore a snapshot taken of our neighborhood as it was being born.

  • Scientists are planning to look at the shape and surface features of Ultima Thule,

  • see whether or not it has rings, and search for clues about how it formed.

  • They're even going to look for an atmosphere, though they don't expect to find one.

  • Aside from Pluto, this is the first close-up look we'll get at an object in the Kuiper Belt,

  • which we didn't even know existed until 1992.

  • But now we understand it's like a vault full of secrets that can tell us about the origin of the solar system.

  • Primitive space rocks may be even more important to us than we realized, too.

  • Earlier this week, a team of researchers announced in Nature Communications that, in a lab,

  • they had made the sugar component of DNA under extraterrestrial conditions.

  • Meaning that it's possible that the building blocks of DNA might not have originated on Earth.

  • Now, this idea isn't new.

  • In the last several decades, we've found other sugars on a few different meteorites.

  • That's led scientists to suspect that the sugars that support life could have originally come to Earth on space rocks.

  • But we still don't understand how sugars got on meteorites in the first place.

  • To figure it out, researchers have been trying to create those compounds under conditions

  • that mimic interstellar space.

  • In this paper, the team made those conditions using a process called ultraviolet irradiation.

  • Ironically, it's what we normally use for sterilizing things, like water.

  • We use it to get rid of living things,

  • but these scientists used it to create organic molecules from conditions that were not biological in the first place.

  • They started with a mixture of frozen water and methanol at -261°C.

  • Kind of like something you might find in a cloud in interstellar space.

  • Then, they shined ultraviolet light on it, like our Sun did to rocks billions of years ago.

  • When the light interacted with the ice, it produced a chemical reaction.

  • And the residue it created contained a bunch of different sugars and other compounds.

  • Many of them had been seen before in similar experiments.

  • But this time, scientists also detected a compound called 2-deoxyribose.

  • This is a type of sugar called a deoxy sugar, which makes up DNA.

  • Along with it, they found compounds that can be derived from deoxy sugars

  • and that we've also found on actual meteorites.

  • That doesn't mean those rocks used to contain deoxy sugars, we don't have evidence for that.

  • But it's not impossible.

  • Either way, this study adds to a list of sugars and other organic compounds that can be created,

  • and have been created, in conditions a lot like the sterile environment of space.

  • It's the most convincing evidence yet that the sugars that gave rise to life on Earth

  • could have been created in totally uninhabitable worlds.

  • Places like comets, asteroids, and clumps of space dust,

  • places we don't associate with life at all.

  • It also hints at how humans came to be.

  • It suggests that, as violent as it sounds,

  • all the meteorites that bombarded the early Earth could have helped life emerge.

  • One thing we really need, though, is direct evidence.

  • So next, scientists will be looking for these deoxy sugars on meteorites themselves.

  • And this study gives them a good reason to keep looking.

  • Thanks for watching this episode of SciShow Space News!

  • This will actually be our last regular news episode for 2018, but don't worry:

  • We have a few special things planned, and we'll be back in January.

  • If you don't want to miss anything, you can go to youtube.com/scishowspace and subscribe.

  • [ ♪ Outro ]

[ ♪ Intro ]

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準備はいいか?ニューホライズンズ、次のターゲットに迫る|SciShow News (Get Ready: New Horizons Is Approaching Its Next Target | SciShow News)

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    林宜悉 に公開 2021 年 01 月 14 日
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