(单词翻译:单击)
We spend a lot of time visiting other planets and moons,
我们花了很多时间参观其他行星和卫星,
but other places in the solar system can also teach us plenty about the history of our neighborhood.
但太阳系的其他地方也能让我们了解它的许多历史。
So in 2007, NASA launched the Dawn spacecraft to investigate the two largest objects in the asteroid belt between Mars and Jupiter:
所以，宇航局在2007年发射了“黎明号”，用于研究火星和木星间的小行星带中的两个最大天体。
a giant asteroid called Vesta, and an icy dwarf planet named Ceres.
其中一颗巨型小行星名为灶神星，另一颗冰冻矮行星名为谷神星。
Dawn was the first mission to orbit something in the asteroid belt,
“黎明号”是第一个在小行星带轨道运行的探测器，
and the first to orbit two bodies besides Earth.
也是第一个围绕地球以外的两个天体运行的探测器。
The mission was supposed to end a year ago,
本次任务原定一年前结束，
but NASA voted to keep it going, and today marks the one-year anniversary of Dawn's extended mission.
但宇航局投票决定它继续进行，今天标志着“黎明号”的扩展任务满一年。
In the last decade, Dawn has taught us a lot more about Vesta and Ceres than we expected,
在过去十年，“黎明号”告诉给我们的灶神星和谷神星信息比预期多得多，
and there are still way more discoveries on the way.
还有更多发现正在等着我们。
Vesta and Ceres were selected as targets because they're so different from each other.
灶神星和谷神星被选为目标是因为它们彼此不同。
Vesta is dense and rocky like the planets closer to the sun,
灶神星密度大、多岩，像离太阳较近的行星，
but Ceres is icy like the smaller worlds in the outer solar system.
但谷神星像外太阳系的小世界一样冰冷。
So visiting both of them was like getting double the science in one mission.
所以参观这两个天体就像一个任务中获得双倍的科学知识一样。
First, Dawn traveled 2.8 billion kilometers to get to Vesta, where it arrived in 2011.
首先，“黎明号”运行了28亿公里于2011年到达灶神星。
Before Dawn, we already knew a little about the asteroid thanks to the Hubble Space Telescope,
在此之前，我们通过哈勃太空望远镜已经对灶神星有了一点儿了解，
like that it has a massive crater on its south pole.
比如，它在南极有一个巨大的陨石坑。
The crater is almost as wide as the asteroid itself.
陨石坑几乎与小行星一样宽。
If Earth had a crater that big relative to its size, it would fill the entire Pacific Ocean basin.
如果地球有一个和它大小差不多的陨石坑，将能填满整个太平洋盆地。
The crater also has a huge mountain on the edge,
陨石坑边缘也有一座大山，
which Dawn eventually confirmed is about 22 kilometers higher than the surrounding terrain.
“黎明号”最终确定它大约比周围的地势高22千米。
That makes it almost three times taller than Mount Everest and one of the tallest mountains in the entire solar system!
它几乎比珠穆朗玛峰高3倍，也是整个太阳系的最高山脉之一。
But besides taking some sweet pictures of the crater,
但除了给陨石坑拍了一些好看的照片外，
one of Dawn's biggest accomplishments at Vesta was confirming a hypothesis we had:
“黎明号”在灶神星的最大收获之一是确认了我们的一个假设：
that some meteorites we've found on Earth came from Vesta.
我们在地球上发现的一些陨石来自灶神星。
Vesta is unusual for an asteroid because it's a lot like a mini-planet.
灶神星是不同寻常的小行星，因为它很像一个迷你行星。
It has a liquid metal core, a mantle, and a crust made out of lava,
它有一个液态金属核、地幔和熔岩外壳。
which we were able to figure out using instruments like Hubble,
这些我们可以用哈勃望远镜之类的仪器确认，
and we haven't really seen an asteroid like that anywhere else in our solar system.
我们还没在太阳系的其他地方见过这样的小行星。
About 6% of the meteorites we've collected on Earth look a lot like they could be from those unique, different layers of Vesta,
我们在地球上收集的约6%的陨石非常像灶神星独特不同的岩层，
and we call them HED meteorites, or howardite, eucrite, and diogenite meteorites.
我们称其为HED陨石，或古铜钙无球陨石、钙长辉长陨石和古铜无球陨石。
Based on their composition, eucrites could have come from the hardened lava on Vesta's surface,
基于其构成，钙长辉长陨石可能来自于灶神星表面的硬质熔岩。
diogenites could have come from inside the asteroid,
古铜无球陨石可能来自于小行星内部，
and howardites look like a mix of the two, which could have happened when Vesta's crater was formed.
而古铜钙无球陨石看起来像两者的混合物，它可能是灶神星的陨石坑形成时发生的。
And Dawn pretty much confirmed that was right!
“黎明号”非常确定这是对的！
Using its different spectrometers, Dawn confirmed the data we'd measured from farther away was correct,
它利用不同的光谱仪，证实了我们从更远地方测量的数据是正确的，
and Vesta is probably responsible for a whole class of meteorites all by itself.
这一整类的陨石都可能来自灶神星。
Which is a pretty big accomplishment for one asteroid!
这对于一个小行星来说是多么大的成就！
After 14 months at Vesta, Dawn packed up its bags
“黎明号”在灶神星待了14个月后，收拾好行囊，
and started a 1.5 billion kilometer, almost three-year journey to the dwarf planet Ceres, where it arrived in 2015.
开始了一个全长15亿公里、为期近三年的奔赴矮行星谷神星的旅程，它在2015年到达那里。
And it's been there ever since.
从那以后就一直在那里了。
As we were approaching Ceres,
在我们接近谷神星时，
one of the first things we noticed were these bright spots like big, shiny reflectors stuck all over the surface.
我们注意到的第一件事是这些明亮的斑点，它们像粘在其表面的闪亮大反射器。
These spots were a huge mystery for a while.
这些斑点在一段时间内是个巨大的谜。
Were they water ice? Clay? Salt? Aliens?
他们是水冰吗？还是粘土？是盐吗？还是外星人？
After analyzing how the spots absorbed light, astronomers concluded they're probably magnesium sulfate,
天文学家们分析了斑点如何吸收光后，得出它们可能是硫酸镁的结论，
or as we call it here on Earth, Epsom salt.
或者我们地球上称之为泻盐。
So you can think of seriousness the next time you're preparing to drink an Epsom salt laxative.
所以你下次准备喝泻盐泻药时，就该想到其严重性了。
The salt deposits were probably created when asteroids smashed into Ceres' surface,
盐沉积可能是小行星撞到谷神星表面时产生的，
exposing the salt-filled ice that was hidden beneath.
撞击使得下面隐藏的盐冰露了出来。
Then, the exposed ice turned into a vapor, and the salt deposits were left behind.
然后，裸露的冰变成了蒸汽，盐沉积被留下了。
We suspected from previous research that Ceres had a lot of water ice,
我们根据之前的研究怀疑谷神星有很多水冰，
but Dawn helped confirm that during its other observations.
“黎明号”在其他的观察报告中证实了这一点。
And the ice seems like it's everywhere, even if it's hiding underneath the surface.
冰似乎无处不在，即使它藏在地表之下。
But this February, Dawn found something that we didn't expect:
但今年2月，“黎明号”发现了一些我们意想不到的东西：
organic molecules, which are the building blocks of life.
有机分子，它们是生命的基石。
Although it couldn't detect exactly what the molecules were,
虽然“黎明号”不能准确地检测出分子是什么，
the spacecraft observed tar-like compounds made of carbon and hydrogen on Ceres' surface in an area of about 1000 square kilometers.
但它在谷神星表面大约1000平方公里的区域内，观察到了碳、氢构成的焦油状化合物。
Because the concentration of molecules is so high,
这种分子的浓度很高，
it seems unlikely that the molecules came from an outside source like an asteroid impact,
似乎不太可能来自外部，如小行星撞击，
since the impact usually scatters molecules all over the place.
因为撞击通常会把分子分散在各处。
Instead, they probably formed from water and heat based chemical reactions on Ceres,
相反，它们可能是谷神星上的水热化学反应形成的，
which could mean it used to have a warm, watery environment.
这可能意味着它曾经有一个温暖、潮湿的环境。
We might investigate that more in the future, but for now,
我们以后可能会调查更多，但现在，
Dawn's main job in its extended mission is to give us a clearer picture of Ceres' surface and composition.
“黎明号”的主要工作是使我们更清晰地了解谷神星的表面和构成。
When cosmic rays from the sun hit Ceres,
当来自太阳的宇宙射线击中谷神星时，
they create radiation and neutrons that Dawn can use to identify the different molecules on and even underneath the surface.
“黎明号”可以利用创造出的辐射和中子，来识别表面上甚至其下的不同分子。
Dawn did a lot of this during its mission,
“黎明号”在此次任务中做了大量的工作，
but since we've got some extra time, we're hoping to get the clearest data we can.
但我们既然有多余的时间，就希望能得到最清晰的数据。
The mission will officially end when Dawn runs out of fuel, which could happen around the end of 2018.
“黎明号”燃料用完就会正式结束任务，这可能要到2018年末。
After that, it'll probably just keep orbiting around Ceres, like a permanent little travel buddy.
此后，它可能继续围绕谷神星运行，就像它的一个永久小旅伴。
But we've already found a lot, and we'll be sure to keep you updated on any exciting discoveries in the future!
但我们已经发现了很多，我们将保持更新未来任何令人兴奋的发现！
Thanks for watching this episode of SciShow Space,
感谢您收看本期的太空科学秀，
and thanks especially to our patrons on Patreon who help make this show possible.
特别感谢Patreon对本节目的大力赞助。
If you want to help us keep making episodes like this,
如果你想继续帮助我们制作这个系列，
go to patreon.com/scishow to learn more.
就登陆patreon.com/scishow了解更多信息吧。
