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Last week, after a three-and-a-half-year road trip and a more than 6-month surveying project, the Japanese spacecraft Hayabusa2 successfully shot an asteroid.
上周，在经过了3年半的路上颠簸和半年的调查项目后，日本航天器隼鸟2号成功着陆于一颗小行星。
Yes, with a bullet. But that wasn't to protect itself, or to save the Earth from Armageddon or anything.
你没听错，是着陆。但这并不是为了保护自己，而是为了避免地球卷入一场恶战之中。
It was to kick up a sample of the asteroid's surface in order to collect it and bring it back to earth.
这样做，是为了获取这颗小行星地表的样本，收集样本后将样本带回地球。
It sounds like a straightforward way to learn what the rock is made of, but when push came to shove things could have gone pretty poorly.
这听起来是个直接的方法，可以了解其岩石的组成，但当有推力存在的时候，情况会十分糟糕。
Hayabusa2 is a follow-up to humanity's first asteroid sample return mission, Hayabusa.
隼鸟2号的前任是隼鸟小行星探测器，是人类第一个返回小行星样本的任务。
That spacecraft visited a stony asteroid called Itokawa in 2005, and returned to Earth with a very small sample of dust in 2010.
2005年的时候，隼鸟小行星探测器到访过一颗岩石颇多的小行星，名作糸川。该探测器于2010年返回地球，还带回了一小抔土。
For this mission, the target was Ryugu, a primitive carbon-based asteroid with an orbit not too far from Earth's.
隼鸟小行星探测器任务的目标是龙宫，这是一颗来自远古的小行星，以碳为主要成分。它的运行轨道离地球不远。
It has a different chemical composition than Itokawa, and likely hasn't changed much since it formed at the beginning of the solar system.
它的化学组成与糸川不同，而且很有可能自它在太阳系之初形成后一直没有什么改变。
So studying it and space potatoes like it can help us unlock our history.
所以，研究它以及太空中与它相似的那些样本可以帮我们解锁太阳系的历史。
Except, there's a lot we're still learning about these kinds of missions, so Hayabusa2 didn't go exactly as planned.
不过，这些任务中还有太多我们未知的东西，所以隼鸟2号的任务并未如期进展。
For example, the sample collection was originally scheduled for last October, but once we got to the asteroid, images revealed that its surface was way bumpier than anticipated.
比如，样本的收集一开始是定在去年10月的，但隼鸟2号抵达小行星后，它发回的图像显示，这颗小行星表面比我们预期的要颠簸不平。
So the team needed longer to find the best place to touch down.
所以，该团队需要更长时间才能找到着陆的最佳地点。
And even when they figured that out, the touchdown itself wasn't all smooth sailing.
而且，即便它们能搞清楚这个问题，着陆本身就不是一帆风顺的。
It actually happened around half an hour before mission control expected it to, although the Japanese space agency didn't mention why.
实际上，着陆比太空航行地面指挥中心预计的要早半小时左右，不过，日本航天局也没有解释原因。
That could have been a huge problem, especially since they instructed the spacecraft to approach Ryugu faster than they had originally planned.
这可能是个大问题，尤其是因为他们指挥隼鸟2号抵达龙宫的速度要比预期的快一样。
But the good news is, it didn't crash.
但好消息是并未发生坠毁事件。
At 45 meters above the asteroid's surface, Hayabusa2 automatically paused its descent, then reoriented itself for the remaining stage.
在龙宫地表以上45米的地方，隼鸟2号自动停止下降，并为剩下的阶段改变方向。
But that required moving one of its antennas and that it could no longer send readings to Earth.
但改变方向就需要移动其中一根天线，而这样它就无法再向地球发送读数。
Which meant that all we could do was sit and wait for a signal that the craft had started getting closer to Ryugu to confirm that touchdown was happening.
这就意味着：我们只能干巴巴地等信号，不知道隼鸟2号何时才会开始向龙宫靠近，也不知道何时才会着陆。
The moving antenna was always part of the plan, but that didn't make it any less nerve-wracking.
移动天线一直是计划的一部分，但这部分始终让人紧绷心弦。
Still, it all worked out! After getting Hayabusa2 back in the right position for communications, mission control could confirm that the command to fire its bullet had been completed.
好在终于放下了这块心里的石头，因为将隼鸟2号调整到合适的位置以进行信号的交流之后，地面调度中心可以确认着陆的指令已经就绪。
We won't know exactly how big of a sample it collected until the spacecraft comes home, but there's a good chance we got something.
在隼鸟2号没返回地球之前，我们也无法精确地得知它收集的样本有多大，但我们还是有很大几率能获得一些东西的。
Hayabusa2 is scheduled to leave Ryugu late this year, but not before collecting at least one more sample.
隼鸟2号预计将于今年晚些时候离开龙宫，但要再收集至少一个样本才能离开。
This one will be from below the surface, which will require the craft to make a small crater using explosives.
这一次的样本将来自于地表以下，这就需要隼鸟2号用炸药制造一个小型的火山口。
If all goes well, these samples will return to Earth in 2020 and will provide data for decades.
如果一切进展顺利，那么这些样本将在2020年返回地球，并在未来数十年中提供数据。
And this isn't the only sample return mission humanity is working on, either.
这也不是人类正在着手的唯一一个返回样本的任务。
NASA's OSIRIS-REx mission will sample the asteroid Bennu in mid-2020.
美国宇航局（NASA）的冥王号任务将于2020年中旬的时候在小行星贝努上采集样本。
And although it's still in development, NASA's CAESAR mission could arrive at a comet in 2029, if the space agency decides to move forward with it.
而NASA的凯撒任务虽然还在准备中，但也将于2019年抵达一颗彗星，除非NASA打算半途而废。
So it's safe to say space potato sampling will likely be a little more common in the future.
所以，保守来说，收集样本很有可能成为未来常见的事儿。
And speaking of space potatoes… how do like that transition?
说到样本，说个转折的插曲吧。
In 2013, astronomers accidentally discovered Neptune's 14th moon hiding in pictures that the Hubble Space Telescope took last decade.
2013年，天文学家无意中发现了海王星的第14颗卫星，这颗卫星隐藏在10年前哈勃望远镜拍摄的图片之中。
But since the moon is so far away and hard to study, the first scientific analysis of it was only published last week in the journal Nature.
但由于这颗卫星太过遥远，很难研究，所以关于它的第一项科学分析上周才发布。
And that finally allowed the International Astronomical Union to give this thing a proper name. Hello, Hippocamp!
借助这项分析，国际天文学联合会给这颗卫星起了个名字——你好，海马！
It sounds pretty goofy, but the name comes from a half-horse, half-fish creature from Greek mythology.
这个名字听起来有点傻，但它源自于希腊神话中一个半马半鱼的生物。
And all of Neptune's small moons get named after mythological water creatures, or figures associated with Neptune or Poseidon.
海王星所有小型卫星都是以神话故事的水生物或者与海王星或者波塞冬有关的人物命名的。
At only 34 kilometers across, Hippocamp is by far Neptune's smallest moon.
海马距离海王星只有34公里的距离，是目前已知的海王星最小的卫星。
It's also super close to the next moon over, called Proteus.
海马离第二远的卫星——海卫八也非常近。
It's less than 12,000 kilometers away, which actually raises some questions.
只有不到1.2万公里的距离，这就不禁让人发问：
See, Hippocamp is also about a thousand times less massive than Proteus.
鉴于海马的质量是海卫八质量的千分之一左右。
So according to the general rules of orbits and gravity, Proteus should have either thrown Hippocamp out of Neptune's system, or merged with it.
那么，根据轨道和引力的通则，海卫八要么应该将海马扔出海王星体系之外，要么就与它合并。
Unless, that is, Hippocamp is a literal chip off the old potato.
除非海马已经与整个体系脱离开了。
Astronomers hypothesize that this moon may have formed several billion years ago, when something like a comet struck Proteus and broke off a piece of it.
天文学家的假设是：海马可能是在几十亿年前形成的，那时候，有一颗彗星撞击了海卫八，并从海卫八上撞掉了一部分。
Or maybe the collision threw out a bunch of smaller pieces in the same general area, and they collected back into a tiny new moon.
也可能是这次撞击在同样的区域产生了一些碎片，这些碎片集合在一起形成了小型的新卫星。
Either way, there are a couple pieces of evidence to support this collision idea.
无论是哪一种情况，都有一些证据支持这个撞击的想法。
For one, models suggest that Proteus has been slowly migrating away from Neptune over time, and billions of years ago, it would have been roughly where Hippocamp is now.
一方面，模型显示，海卫八一直在逐渐远离海王星。而且在几十亿年前，海卫八大致就在海马现在所在的位置上。
Also, we've detected a huge impact crater on Proteus, which is more than large enough to have come from a collision that would have made Hippocamp.
此外，我们勘测到海卫八上有一个大型的撞击坑，导致这个撞击坑的撞击可能也造就了海马的诞生。
As always, scientists will need to keep investigating to say anything for sure.
还是跟以前一样，科学家需要持续研究才能得出准确的结论。
But one thing is obvious: Hippocamp backs up our previous idea that the Neptunian system is chaotic.
但有一点是明显的：海马印证了我们之前的想法，即海王星体系很混乱。
It might look all peaceful from a distance, but the area around Neptune is kind of like a giant orbiting traffic jam.
虽然从远处看一片祥和，但海王星附近的区域有点像大型车祸现场。
For example, we know that the planet captured its largest moon, Triton, after making its first generation of satellites.
比如，我们都知道海王星吸引着其最大的卫星——海卫一。在此之前，海王星先是形成了第一批卫星。
So when Triton rolled in, it disrupted everybody's orbit and caused all kinds of collisions.
海卫一的加入扰乱了其他卫星的轨道，引发了许多磕碰。
We also know that activity from comets has obliterated a bunch of moons.
我们还知道，诸多彗星的活动导致许多卫星消亡。
In fact, the team studying Hippocamp estimates that it has been broken apart and reformed nine different times over the past 4 billion years.
实际上，研究海马的这个小组估测，在过去的40亿年间，海王星体系曾分崩离析，重组了9次之多。
So this new study helps reinforce what we've already suspected.
所以这项新研究助力印证了我们的想法。
And as a bonus, the team studying Hippocamp was able to release new data on the other six, small moons inside of Triton's orbit.
意外收获是：该小组还发布了另外6颗卫星的新数据，它们都是海卫一轨道上的小卫星。
That included data on Naiad, Neptune's innermost moon, which hasn't been seen since Voyager 2's flyby in 1989.
其中包括海卫三——海王星最内侧的卫星。而自1989年旅行者2号飞近探测之后就未曾有人见到过它了。
So in addition to saying “hi” to Hippocamp, these scientists are helping us better understand the evolution of our outermost planetary system.
除了向海马致敬之外，这些科学家还在帮助我们更好地了解我们最外侧行星体系的演进过程。
Between this group and the Hayabusa2 team, it seems like everybody is learning about the solar system's evolution these days and we're pretty excited about it.
除了这个群体和隼鸟2号团队之外，似乎大家最近都在关注太阳系演进的事情，我们对此都颇感兴趣。
Thanks for watching this episode of SciShow Space News!
感谢收看本期的《太空科学秀》！
Since we haven't sent a spacecraft to Neptune in about thirty years, there's a lot we're still trying to understand about the planet.
鉴于近30年来，我们都未曾向海王星发送过航天器，所以我们对海王星还有诸多不了解的地方。
And while the Hubble Space Telescope can clearly do a lot, it can't do everything.
虽然哈勃望远镜能帮助我们很多，但却不能事事详尽。
If you'd like to learn what mysteries we could solve with a Neptune orbiter, you can watch our video all about it.
如果您想了解向海王星发送人造卫星能解开什么谜题的话，您可以看我们与此有关的视频。
