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October was kind of a bittersweet month for space scientists.
10月对于天文学家来说是个悲喜交加的月份。
NASA successfully fixed problems with two satellites, the Hubble Space Telescope and the Chandra X-Ray Observatory, but they also had to say goodbye to two more.
喜的是：美国宇航局成功解决了2颗卫星——哈勃太空望远镜和钱德拉X射线天文台——的故障问题；悲的是：另外2颗卫星光荣退役了。
Last week, both the Kepler Space Telescope and Dawn mission ran out of fuel and came to an end.
上周，开普勒太空望远镜和黎明号由于用尽燃料而停止了运转。
But over their 16 cumulative years of operation, they showed us that our universe is even more amazing than we'd imagined.
但它们16年来的连续运作已经让我们看到——我们所生活的宇宙比我们曾经想象的更为精彩。
Here's some of what we learned.
下面来一数过去16年来的发现成果。
NASA's Kepler Space Telescope was originally going to be called FRESIP, which stood for FRequency of Earth-sized Inner Planets.
美国宇航局的开普勒太空望远镜本来要叫另一个名字的——FRESIP，即跟地球同等大小的内行星频率。
But thankfully, somebody changed their mind and named it after the famous astronomer instead.
不过，谢天谢地，有人改为以知名天文学家开普勒来命名这颗卫星。
The mission launched in 2009, and it used the transit method to find planets beyond our solar system,
开普勒发射于2009年，是用中天法来寻找太阳系外的行星。
monitoring over half a million stars to try and detect tiny dips in light that could indicate a planet was passing by. And it totally worked!
开普勒监测了50多万颗恒星，试图探测亮度的任何变化情况，从而推究是否有行星经过。这招屡试不爽！
Less than a year after launch, Kepler found its first planets, a bunch of what scientists call hot Jupiters.
在发射后不到一年的时间里，开普勒发现了第一批行星，天文学家将这些行星称之为热木星。
They're large gas giants that orbit super close to their stars.
这些行星都是体型庞大的气体巨星，跟自己环绕的恒星离得特别近。
We don't have any of those planets around here, so discoveries like this offer huge insights into how other star systems evolve.
我们附近是没有这样的行星的，所以这样的发现为我们提供了极好的信息，让我们了解到其他恒星体系是如何演化的。
Over its two missions, the primary Kepler mission and the later K2, the telescope went on to find more than 2700 confirmed exoplanets.
开普勒执行了2个阶段的任务，即首次开普勒任务和随后的K2任务。任务期间，开普勒发现了27000多颗已经证实的系外行星。
That's more than two-thirds of all the confirmed exoplanets we've discovered.
这个数字占我们发现的所有系外行星的2/3。
And along the way, it painted a picture of just how diverse our galaxy is.
这个发现的过程也展现了太阳系的多样性。
Even accounting for those hot Jupiters, most of the planets Kepler observed aren't anything like what we have in our solar system.
包括热木星在内，开普勒观测到的大多数行星跟我们在太阳系里看到的行星完全不同。
Instead, they're somewhere in size between Earth and Neptune.
这些行星的的大小根本不在地球和海王星之间。
And while it has been historically easier to find larger planets, the fact that there are so many suggests our solar system could be at least a little special.
虽然在天文学历史上，发现大行星比较容易，但这么多的大行星可能表明我们的太阳系至少是有一些特别之处的。
But not all of Kepler's discoveries were super weird and exotic.
但开普勒的有些发现成果是比较中规中矩的。
It also found planets a little more similar to Earth, and that could help us understand how our home got to be the way it is.
开普勒还发现了一些跟地球大小相近的行星，这或许能帮助我们理解地球是如何成为今天这般模样的。
For example, in 2011, Kepler found the first solid evidence for a rocky exoplanet.
比如，2011年的时候，开普勒首次发现证据可以实锤某岩石质地的系外行星。
Then, in 2014, it found the first roughly Earth-sized planet in its star's habitable zone.
随后，2014年的时候，开普勒在该恒星的宜居地带首次发现了跟地球大小相当的一颗行星。
That's the distance from a star where, if a planet has a thick enough atmosphere, water could exist on the surface.
跟恒星这样距离的行星，如果有足够厚的大气层的话，其表面是有可能有水的。
And in 2018, the telescope may have even found the first moon around an exoplanet!
随后，2018年，开普勒可能发现了系外行星附近的首颗卫星。
Unfortunately, for some time now, Kepler had been running low on the fuel it needed to perform steering maneuvers.
不幸的是，一段时间以前，我们发现开普勒的燃料余量已经不足，无法进行转向等操作了。
And on October 30th, NASA announced that it had finally run out.
10月30日，美国宇航局宣布，开普勒燃料已经彻底用完。
That means we can't point it toward anything we want to study, or point it back toward Earth to send data home.
也就是说，我们无法再通过开普勒来研究我们想要研究的东西，也无法让它向地球发送数据了。
So now, it's just stuck in orbit around the Sun.
目前，开普勒被困在了太阳附近的轨道上。
But it was a really good telescope while it lasted!
但开普勒工作期间表现十分出色！
While Kepler was studying distant solar systems, the Dawn mission was investigating the asteroid belt:
开普勒研究的是遥远的恒星体系，而黎明号研究的则是小行星带——
the rocky leftovers from when our solar system formed.
太阳系形成后残留的石质物体。
Studying those leftovers gives us insight into what exactly happened those four and a half billion years ago.
研究小行星带可以让我们了解过去450亿年来发生了什么。
Dawn launched back in 2007, and became both the first spacecraft to orbit something in the asteroid belt and the first one to orbit two foreign worlds.
黎明号发射于2007年，是小行星带里环绕某物体飞行的首个航天器，也是首个环绕2个恒星体系飞行的卫星。
In 2011, it made its first stop at the asteroid Vesta, the second largest body in the belt.
2011年，黎明号首次在小行星维斯塔驻足，是小行星带第二大的物体。
We've talked about some of Dawn's accomplishments at Vesta before, like how it studied a giant mountain on the south pole.
之前的节目有讨论过黎明号的发现成果，比如它是如何助力研究南极某巨峰的。
But this spacecraft did a lot more, too.
但黎明号的成绩也远不止于此。
For example, Dawn revealed the presence of certain minerals we hadn't expected to find on the asteroid.
比如，黎明号揭示乐小行星上有我们不曾料到的某些矿物质存在。
Specifically, ones with water molecules stored in them.
这些矿物质里含有水分子。
They likely came from small collisions, and their existence contradicts the old idea that Vesta is just a big, dry rock.
这些矿物质可能是由一些碰撞产生的，它们的发现与我们之前的观点矛盾，因为我们之前认为维斯塔是十分干燥的大型岩石。
Dawn also confirmed that Vesta has a layered interior with a separate crust, mantle, and core, kind of like the inner planets.
黎明号还证实了一件事——维斯塔内部层层相扣，包括彼此分隔的地壳、地幔、地心，跟内行星很像。
That makes it an important piece of evidence in understanding planetary formation.
这个证据非常重要，可以帮助我们理解行星的组成。
Because if a little asteroid has these layers, that suggests planetesimals, the building blocks of planets, might have had them, too.
因为如果小行星也有这样的层级结构，那就表明，行星组成的基础物质星子可能也是小星星的组成成分。
In 2012, Dawn left Vesta for Ceres, the only dwarf planet closer than Pluto.
2012年，黎明号离开维斯塔，前往谷神星。谷神星是比冥王星还近的矮行星。
It arrived in 2015, and started discovering a ton about the object's composition, like that it had clays full of ammonia.
黎明号2015年抵达谷神星，开启了发现谷神星组成架构之旅，比如黎明号发现谷神星的黏土里富含氨。
That's actually pretty strange because, given its distance from the Sun, Ceres is too hot for ammonia to condense into a solid.
这种现象是很奇怪的，因为考虑到谷神星跟太阳的距离，其温度一定很高，那么氨按理来说是不会浓缩成固体的。
So scientists now think that Ceres either formed in the outer solar system and migrated inward, or is partially made up of smaller bodies that formed out there.
所以，科学家现在的想法是：谷神星要么是在太阳系外部形成的，之后向内进行了迁移；要么是由比它小的物体组成的。
Dawn also spotted an abundance of organic molecules in one of Ceres's craters, which may have been formed in the dwarf planet's interior.
黎明号在谷神星其中一个火山口里面发现了大量有机分子，这些分子可能是在谷神星内部形成形成的。
Organic compounds are commonly made by life, but don't get your alien-hunting gear out yet.
有机化合物一般都是由生命产生的，但也不要现在就放弃搜寻外星人的想法。
So far, the only molecule that's been identified is some kind of aliphatic, which is a pretty simple molecule made of hydrogen and carbon chains.
目前为止，经过确认的唯一分子是脂肪族分子，是非常简单的分子，只由氢和碳链组成。
So this might just mean that organic molecules aren't that rare.
所以这可能意味着有机分子并不是那么稀有。
During its mission, Dawn traveled nearly 7 billion kilometers and taught us a lot.
在执行任务期间，黎明号行进了近70亿公里，让我们受益匪浅。
But it couldn't last forever. On October 31st, Dawn ran out of its propellant.
但黎明号也不能永久陪伴我们。10月31日，黎明号推进燃料也用完了。
That meant it was unable to rotate its antenna to check in with Earth, so the team ultimately had to declare the spacecraft defunct.
这就意味着黎明号不能通过天线与地球联系，所以该研究小组最终宣布黎明号退役。
It will continue to orbit Ceres for up to 50 years, but eventually, it will come crashing down.
黎明号还将继续环绕谷神星飞行最多50年的时间，但最后还是免不了坠落的结局。
The good news is, Dawn will be teaching us about the asteroid belt for years to come, since the mission collected tons of data, including nearly 100,000 images.
好消息是——黎明号将让我们在未来数年中了解谷神星，因为黎明号收集了大量数据，包括近10万张图像。
The end of Kepler and Dawn is a sad moment in astronomy, but at least there's a silver lining.
开普勒和黎明号的结局对于天文学而言是惨剧，但也有好的一面。
Kepler's replacement, called TESS, launched earlier this year and has already started capturing data.
开普勒的继任者TESS已于今年年初发射升空，并已经开始收集数据了。
And while it will likely be a while before another craft visits Vesta or Ceres, we have plenty of spacecraft working on other asteroids.
而且下一个航天器到访维斯塔或者谷神星还需要一段时日，但我们已经部署了很多航天器在其他小行星上了。
That means more exciting space news is always on the horizon.
也就是说，很快就要有激动人心的新闻了。
Thanks for watching this episode of SciShow Space News!
感谢收看本期的《太空科学秀》！
If you'd like to learn even more about what Dawn did during its mission, you can watch our episode from 2017 about some of its other accomplishments.
如果您想了解更多有关黎明号在执行任务期间所做的工作，您可以观看我们2017年的一起视频，里面详细介绍了黎明号的其他成就。
