一路都是巨石

对。

Right.

所以当时并没有出现‘天哪，我们该怎么办？’这样的情况。

So there was no like, Oh no, what do we do?

我们该后退吗？

Do we back away?

你知道，整个操作已经完成了。

You know, like the execution was done.

更像是‘哇，这发生了。’

It was more like, Woah, that happened.

然后，我们检查一下航天器是否正常，诸如此类的事情。

And, you know, let's check and make sure the spacecraft is healthy and all that good stuff.

结果发现我们没事。

It turned out like we're okay.

成功后退了。

Were able to back away.

而且，你知道，管理层层面有很多活动，用来评估采样任务的成功与否。

And, you know, there was a lot of activity kind of at the management level to assess like the success of the sample collection.

所以他们拍了照片，确认我们确实收集到了东西，看起来确实成功了。

So they were taking photos and making sure like we got stuff and it looked like, yeah, we did.

让我们把它收好，确保它安全无虞。

Let's stow it, make sure we've got it safe.

因为其中一个关键的决策点是：如果这次没成功，我们是否要再试一次？

Because one of the key decision points that had to be made was do we try again if that one didn't work?

我们迅速决定：不，不再试了。

And we quickly decided, no, we're not trying again.

风险太高了，尤其是经历了刚才那一幕之后。

It's too risky, especially after what we just saw.

让我们趁胜收兵，把样本带回去吧。

Let's, you know, stop while we're ahead and take this back.

但那一刻真的非常激动人心。

But the moment was really exciting.

这件事发生在半夜。

It happened it was in the middle of the night.

其实，这挺有趣的。

Well, actually, it's funny.

OSIRIS-REx采样事件，我现在记起来了，是2020年10月20日，因为那正好是我结婚后的第三天。

The OSIRIS REx sampling event was I remember now it was 10/20/2020 because that was three days after I got married.

天哪。

Holy cow.

当时我在法国，数据正在传回，大约是欧洲时间晚上11点。

And I was in France at the time and it was happening the data were coming down, it was around eleven p.

晚上。

M.

在欧洲，所以当时是早上四点。

In Europe, so it was like four a.

早上。

M.

或者不，那应该是下午中间时段，我不太记得了。

Or no, it was it was like middle afternoon or I don't remember.

我当时躺在床上，我妻子正要睡着，而我正盯着我们用Slack或其他工具建的团队聊天群。

And I was laying in bed and my wife falling asleep, and I was just on like the team chat that we had through Slack or whatever it was.

是的。

Yeah.

你知道，所有人都疯了，第一批图像陆续传下来，真的挺有意思的。

You know, everyone just freaking out and, you know, initial images coming down and, you know, just it was fun.

因为整个团队都分散在各地。

Just because the team is just like the team was all spread out.

那是疫情期间，几乎所有人都在家远程工作。

This was during the pandemic, so pretty much everyone was remote.

一开始有实时的现场播报，大家都知道任务正在进行，然后中断了六七个小时，直到第二天早上我刚醒来时，第一批图像才传下来。

And, you know, just there was the initial kind of live play by play where they knew it was happening, and then there was a a six or seven hour pause and it was actually the next morning, just as I was waking up, that the first images were coming down.

那时才真正有趣，团队聊天里都在惊呼：天啊，表面炸得这么厉害？

And that's where it was really fun and the team chat just being like, Holy crap, the surface, how much it exploded?

人们立即开始分析这些图像，互相传递，标注图像、标记内容、指出重点，并通过团队聊天发送回去。

And people immediately analyzing the images, you know, passing around, like annotating the images, marking things, pointing things out, sending it back through the team chat.

就像说，看这块石头是怎么移动的，还有看

Be like, look at how this rock here moved and look

我们在那边做了什么。

at what we did over there.

这就是参与大型科学团队的有趣之处，因为你们有来自不同背景的众多专家，这个人会指出某件事，你会惊呼：天啊，我根本不会注意到这一点。

And so that's the fun part of being on these big science teams, is because you've got like so many experts from so many different backgrounds that like, you know, this person will point out this one thing and you're like, holy crap, I would have never thought to notice that.

但我真的很高兴你在这里，因为你刚刚指出的这一点实在太棒了。

But like, I'm so glad that you're here because that is really cool what you just pointed out.

所以，那确实是一段特别的时光。

So yeah, that was a really special time.

甚至在那之前，疫情前，我们都在图森一起工作，坐在开放的隔间里，大约有三四十名来自世界各地的科学家。

And even before that, like before the pandemic, when we were all in Tucson together and we were in like an open cubicle space and there were about like 30 or 40 scientists all in this area, international.

我们有不少来自美国的人，但也有很多来自欧洲各地的人。

So we had a bunch of people from The US, but we had a lot of people from all over Europe.

我们还有来自日本的人。

We had people from Japan.

太棒了。

Super cool.

在这样的环境中工作真是令人惊叹。

Just like amazing atmosphere to be working in.

太棒了。

So awesome.

好的。

Alright.

现在我们来更详细地谈谈这篇论文。

Let's talk a bit more about the paper in detail now.

早在2007年，斯皮策太空望远镜就表明，贝努星表面像沙滩一样迅速升温和降温。

Way back in 2007, the Spitzer Space Telescope showed that the surface of Bennu heats and cools rapidly like a sandy beach.

因此，当航天器抵达时，NASA预期会看到这样的现象。

So that's what NASA expected to see when the spacecraft got there.

之前在讨论中，你提到了‘热惯性’这个词。

Earlier in the pod, you said the words thermal inertia.

请用五岁孩子能听懂的方式解释一下热惯性。

Please explain thermal inertia like I'm five.

热惯性我之前稍微提过一点，就是指某物在白天有多容易变热，以及在夜晚有多快变冷。

So thermal inertia is I talked about it a little bit before, just is how easily something heats up during the day and how rapidly it cools off at night.

有些材料白天升温非常快，晚上降温也很快，变得很冷，而另一些则相对温和。

So certain materials heat up really quickly and cool down and get really cold at night and others are kind of more muted.

这就像沙滩上的沙子，阳光下会变得非常烫，脚很容易被烫伤；而像大石头表面或者砖墙就完全不同，到了晚上，沙子会变得很冷，但如果你站在一栋建筑的砖墙边，仍然能感受到它散发出的余热。

It's like the difference between sand where it gets really hot in the sun on the beach and you can burn your feet really easily versus a nice bouldery surface or even like a brick wall and vice versa at night the sand gets very cold, whereas you stand next to a brick wall in a building, you can still feel the heat radiating off of it.

这种差异正是由于热量在这些材料中传导方式的不同。

And that difference is just due to how heat can flow through those materials.

沙子由无数微小的颗粒组成。

So sand, it's made up of all these little particles.

这就像有海量的表面积。

It's like a crap load of surface area.

是的，有很多微小的接触点，热量很难通过。

Yeah, there's just lots of little contacts and it's very hard for the heat to make its way through.

而砖块或巨石表面则是一种致密的介质，热量能够有效地传导。

Whereas, you know, a brick or a boulder surface, you've got just this nice dense medium and heat is able to effectively conduct through it.

因此，我们可以观察这些温度变化，从而了解天体表面的物质组成，比如小行星，而无需真正登陆表面，也不需要那种能看清毫米级颗粒的超高分辨率相机。

And so we can look at those temperature fluctuations and learn about what's on the surface of an object, including an asteroid without actually having to go to the surface or having a crazy, crazy, super high resolution camera that can see, you know, millimeter sized particles or whatever.

所以，借助斯皮策太空望远镜，我们结合热模型估算出了热惯性值，这个数值介于岩石（热惯性很高）和尘埃（热惯性很低）之间。

So yeah, the Spitzer Space Telescope, we were able to fit it with thermal models and extract a thermal inertia estimate and the value kind of sat between like, you know, rock has a really high thermal inertia and dust has a really low thermal inertia and it was sort of in between.

因此我们认为，这有力地证明了我们看到的可能是岩石和细小颗粒的混合物。

So we thought, all right, that's pretty good evidence that we're probably seeing some rock and some small stuff.

你知道，我们看到的这两种特征的混合，与隼鸟号在丝川小行星上观测到的情况是一致的。

You know, we're seeing a mixture of those two signatures that's consistent with what Hayabusa saw at Itokawa.

你可以做一些基本假设，比如假设整个小行星表面都覆盖着相同大小的颗粒，然后根据热惯性计算出颗粒尺寸，结果大约是几厘米。

You know, you can like make some basic assumptions and say what if the whole asteroid is covered in the same particle size and you can calculate a particle size from thermal inertia and the particle size was like a couple centimeters.

所以我们觉得，这有力地表明表面应该存在比这更小的物质。

So we're like, all right, that's pretty good evidence that there should be like stuff smaller than that on the surface.

雷达数据也似乎表明了这一点。

And the radar data seemed to indicate that too.

雷达数据显示，表面的上层区域，其雷达散射特性表明该区域密度不高。

The radar data showed that the upper surface, the way that the radar scattered on the surface was indicative of it being not very dense.

好的。

Okay.

所以我们有了这些观测结果。

So we have these observations.

我们根据热惯性测量本以为会是某种情况，但结果完全不是那样。

We based on the thermal inertia measurements expected to be a certain way, and it was completely not that way.

所以我们遇到了一个热力学问题。

So we have a heat problem.

是的。

And Yep.

一旦意识到这些是巨石，人们原本预期它们应该是多孔的。

And the rocks were sort of expected to be porous once you realized it was boulders.

对吗？

Is that correct?

你的意思是，唯一能解释这个差异的原因就是这些岩石真的非常孔隙。

Like, you're like, they're the only explanation for this discrepancy is that the rocks are really freaking porous.

但结果发现，孔隙度并没有完全解释那里的所有差异。

But it turns out the porousness did not account for all of the discrepancy there.

这样描述公平吗？

Is that is that a fair characterization?

是的。

Yeah.

我们之前就知道岩石可以具有不同的特性，当然也会有不同的热惯性值。

So we had known beforehand that like rocks can have different properties and of course, different thermal inertia values.

但这次的情况远比任何人预想或计划的都要极端得多。

It was just like this was far more extreme than really anyone had anticipated or planned for.

如果你用一些非常简单的模型来计算，有些模型甚至预测岩石的空隙率达到50%，这远远超过了任何已测量过的陨石。

Like if you apply some like really simple models, would, you know, some of them were predicting that like the rocks are 50% void space, which is just way higher than any meteorite that had ever been measured.

我们还发现小行星表面存在明显不同的岩石群体，因为我们观察到了热惯性的趋势。

We also saw that there were distinct populations of rocks on the surface of the asteroid, because we saw trends in thermal inertia.

有些区域热惯性高，有些则低，因为我们能够绘制出这些温度分布。

Some areas were high and some were low, because we were able to map those temperatures.

热惯性最低的区域，表明孔隙空间最多或岩石最松散、充满空洞，这些区域恰好分布着更多深色、尖锐、碎屑状的巨石。

The areas with the lowest thermal inertia, which would be indicative of like the most pore space or like the weakest, most void filled rocks, that corresponded with areas that had more of the really dark, really jagged, rubbly looking boulders.

热惯性较高的区域则分布着更棱角分明、呈块状、具有锐利边角的巨石，它们形状更接近方形或几何形，颜色稍亮，表面更平滑。

The areas with higher thermal inertia had boulders that were more angular and block like with like sharp corners and, you know, they're more square or like geometric in shape, and they're slightly brighter and had smoother surfaces.

因此，这让我们意识到，我们观察到的热惯性趋势其实与巨石相对于细沙和尘埃的相对丰度无关。

So that kind of clued us in like, okay, the thermal trends we're seeing here don't really have anything to do with like the relative abundance of boulders versus fine sand and dust and whatever.

这仅仅是巨石A和巨石B的区别。

It's just boulder A and boulder B.

我们看到了两种类型的岩石，它们只是以不同方式分布在小行星表面。

We're seeing two types and they just, you know, are distributed in different ways across the surface.

所以，这基本上就是探测器在小行星上任务的尾声了。

And so, you know, that's kind of like that was the end of the chapter of the spacecraft at the asteroid.

你知道，我们利用了手头的信息，写了论文，说明了我们的看法。

You know, we took the information that we had and we wrote papers about it and said, all right, here's what we think.

我们认为，小行星表面主要由两种不同类型的巨石组成。

We think that there are two different boulder types that dominate the surface.

它们似乎具有不同的热特性，这意味着它们可能具有不同的物理特性。

They appear to have different thermal properties, which means they probably have different physical properties.

深色的巨石似乎非常多孔，这可能对撞击时的反应方式产生影响。

The dark ones appear to be really porous, which may have implications for, you know, if you crash into one, how it would respond.

抱歉，你说的多孔是指多高？

Sorry, how porous are we talking?

是像太空浮石那样的吗？

Is it like space pumice?

不，没那么高。

No, not quite.

大约50%，而浮石大约是80%，或者说是，没那么高。

Like 50%, whereas pumice is like 80% or, you know, yeah, not quite that high.

但作为对比，我们之前分析过的类似陨石，孔隙度最高也不过20%到30%。

But like for comparison, the analogous meteorites that we had analyzed had porosities no higher than like 20 or 30%.

所以这几乎是两倍。

So this was like double.

所以我们觉得，哇，这些材料真是奇特。

So we're like, Woah, okay, these are exotic materials.

我们之前也推测过，也许地球上根本没有这类物质，因为陨石进入地球大气层时会变成火球，而如果这种物质曾经穿过大气层，可能早就被彻底摧毁了。

And we did speculate earlier, like maybe we don't have any of these on Earth because, you know, we have meteorites that enter Earth's atmosphere and they're fireballs, and maybe if this stuff ever came through the atmosphere, would just be obliterated.

所以也许我们根本无法通过自然的样本输送——也就是陨石坠落——来获得这样的东西。

So maybe we could never get something like this via natural sample delivery, which is AKA just a meteorite fall.

是的。

Yeah.

对。

Yeah.

我们就说到这里。

So that's where we left off.

我们觉得，这一章就此结束了。

We're like, all right, that chapter's closed.

我们已经采集了样本，准备带回去，看看我们的推测是否正确。

We've collected samples and we're going to bring them back and try to figure out if we were right.

因此，这项工作的部分目的就是检验我们在小行星上提出的假设。

So part of this exercise is just testing the hypotheses we made when we were at the asteroid.

这就是科学的精髓。

That's science at its finest.

你观察到某种现象，做出观察，也许当时你对这个发现感到惊讶。

You see an observation, you make an observation, maybe you were surprised at the time you're making the observation.

这并不是你预期的结果。

It's not what you expect.

然后你提出一些假设，并对这些假设进行验证。

Then you make some hypotheses and you test the hypotheses.

其中之一是这些深色巨石具有极高的孔隙率，但同时也有人推测，它们可能以某种特定方式开裂，从而抑制了热传导。

And so one of them was that these dark boulders are super porous, but it also was speculated like maybe they're cracked in a particular way that inhibits heat flow, too.

所以，我不打算说，我在分析实际样本的论文中发现的一个结果是，这些样本裂纹极多，这也是它们热惯性低的原因之一。

So, you know, I'm not going to say that like one of the findings in my paper where we analyzed the actual samples was that they are extremely cracked, and that's one of the reasons they had a low thermal inertia.

这对我们来说并不是什么意外。

That wasn't necessarily a surprise to us.

只是通过测量来证明这一点非常困难，这也是我认为这篇论文是一个重大突破的原因之一。

It was just really hard to prove through the measurements, which is one of the reasons that the paper, I feel like, was a big advancement.

这并不是一件 straightforward 的事情。

It wasn't just like a straightforward thing to do.

所以，是的，我们想做的一件事就是理解各种因素的相对作用，更宏观地说，当我们未来观察另一个小行星并获得热惯性估算值时，我们该如何解读它？

And so yeah, that was one of the things we wanted to do, is understand what are the relative roles, and just like even higher level, like when we look at another asteroid and we get a thermal inertia estimate moving forward, how do we even interpret that?

因为我们以前曾经被误导过。

Because we've been fooled once before.

那么，现在的前进方向是什么？

So what's the path forward now?

要做到这一点，你必须把样本带回地球，仔细观察其微观结构，然后恍然大悟：原来如此——这整个过程中的关键一步。

And to do that, you kind of got to, you know, bringing the samples back and being able to look at the actual microstructure and be like, Ah, that's why, is an important part of that process.

当采样器那个小装置在关闭时出现问题，嗯。

When the Tag Sam, when the little collector thingy was having issues with closure Mhmm.

容器关闭出问题时，群聊里的氛围是怎样的？

Of the container, what is the vibe like in in the group chat at a time like that?

我简直无法想象那段时间会有多轻松或平静。

Like, I I can't imagine that was super fun or or like chill.

如果你有机会让但丁上节目，这个问题问他挺好的，因为当时处理这个情况的就是他。

That's a good question to ask Dante if you ever get him on the show, because he was the one who had to deal with that situation.

我没有参与那些对话。

I was not a part of those conversations.

但我认为当时他们必须迅速做出决定，因为他们知道每拖延一秒，颗粒物就在不断泄漏，质量也在下降。

But I think that there was an extreme sense of urgency to decide because they knew that every moment they waited, particles were leaking out and that mass was going down.

所以他们必须决定：是直接收纳样本返航，还是再试一次？

So they had to decide, do we stow and go home or do we try again?

原本我们打算等上几周再做任何决定。

And so originally, we were going to wait like weeks before making any decision.

他们甚至打算伸展机械臂，让航天器旋转起来，以尝试测量质量。

And they were even going to like spin the spacecraft around with the arm extended to try to get a mass measurement.

基本上就像一个转动惯量的测量。

Basically like a moment of inertia thing.

我们之前就知道该怎么旋转了。

They We decided knew how we would spin previously.

现在我们知道带着这个样本时该怎么旋转了。

Now we know how we're spinning with this sample.

因此，大概就能知道里面有多少重量了。

Therefore there's that much weight in it kind of thing.

没错。

Exactly.

是的。

Yeah.

他们说：不，我们不这么做。

And they said, No, we're not doing that.

直接收起来吧。

Like Just stow it.

收起来。

Stow it.

直接收好就走。

Just stow and go.

所以，这其中一部分是因为首席研究员丹特需要与NASA合作，而像这样关键的飞行决策——比如决定收纳样本——必须经过正式的决策流程。

So some of that is, you know, like the PI Dante having to work with NASA and, you know, there's a formal decision making process that needs to be carried out in order to make those really critical mission decisions like that, like the decision to stow the sample.

必须有特定人员签字确认。

Certain people are required to sign off on that.

所以我认为他们只是在加快这个流程。

So I think that they were just expediting that.

有道理。

Makes sense.

那么，你有没有曾预计岩石的严重开裂会是解释热差异的原因？

So did you, at any point, expect this like extreme cracking of the rocks to be the answer for the heat discrepancy?

还是说这完全是个意外？

Or was that like a total surprise?

我想你之前提到过，你认为可能会有一些开裂。

I guess you kind of said that you thought there might be some cracking.

我 honestly 认为这会是解释原因的答案。

I honestly thought that that was going to be the explanation.

不错。

Nice.

是的。

Yeah.

是的，这确实被预测到了。

Yeah, it was definitely predicted.

甚至有一些论文发表过理论模型，表明如果你的巨石表面下方有一条与表面平行的裂缝，就足以降低热惯性，从而产生我们观测到的特征。

There were even like some papers where people had published just like theoretical models showing like if you had, if like this is your boulder surface and you have one crack below the surface that's parallel to the surface, you can suppress the thermal inertia enough to create the signature that we saw.

但我一直有点怀疑，认为表面下方恰好会有一条完美且无限长的裂缝。

I was always a little skeptical though, this idea that there would just be one perfect infinite crack at just the right depth below the surface.

但我认为裂缝肯定是其中的一部分。

But I figured like cracks are going to be a part of it.

不过我担心的是，如果这不是原因，而这些东西真的只是非常多孔且几乎像绒毛一样，那么在采集和返回样本的过程中，这些物质可能会被彻底摧毁，因为它们会被剧烈摇晃，等我们打开时，这些物质就不存在了。

One of my concerns though was that if that's not the explanation and it is indeed that these things are just super porous and almost like fluffy, that the process of collecting and returning the sample would obliterate those materials because they'd get shaken up so much we'd open it up and that material would no longer exist.

基本上就变成灰尘了。

It'd just be like dust, basically.

是的。

Yeah.

哇。

Wow.

因此，我们对样本的初步筛选部分是试图比较大颗粒和小颗粒，看看是否存在这种差异——比如，大颗粒可能只是最坚硬的部分，而所有细小物质，也许那些蓬松的物质都被压缩到了更细的颗粒尺寸中，因为它们都被打碎了。

So part of our initial triage of the sample was trying to compare the big particles to the small ones to see if there was like this discrepancy, like maybe the big ones were only the hardest ones and all the small stuff, like maybe you'd find the fluffy stuff like relegated to the finer particle sizes because it all got broken up.

但我们并没有看到令人信服的证据支持这一点。

But we didn't really see compelling evidence for that.

但你知道，我们确实一直在留意这种可能性作为解释。

But you know, we definitely on the lookout for that as a possible explanation.

天啊，那可就太糟糕了。

God, that would be Oh, man.

辛辛苦苦去采集样本，好不容易把东西收好、封存起来。

Just just like to go through all the trouble to actually collect a sample, to actually get the thing closed and stowed.

结果带回来一看，全都变成了一堆碎尘。

And then you get it back and it's all just like obliterated dust.

这就像是去超市购物，回家后发现所有的鸡蛋都碎了。

It'd be like going to the grocery store and you get home and it's just like all your eggs are smashed or something that.

这得相当于花了八亿美元啊。

Like times $800,000,000 or something.

但这种多孔性和密度的问题，实际上对样本的初步筛选起到了非常关键的作用，因为我们原本就预测不同颗粒在密度或孔隙率上可能存在巨大差异。

But this whole porosity and density thing actually fed into the initial triage of the sample in a really important way because we had predicted that there may be really big differences between particles in their density or really their porosity.

也就是说，高孔隙率、低密度。

So, you know, high porosity, low density.

我们在NASA约翰逊航天中心的保管设施中，专门设计了在不污染样本的前提下测量密度和孔隙率的方法。

We built in ways to measure density and porosity in the curatorial facilities at NASA Johnson Space Center without contaminating the samples.

因为科学团队，我们有一个特定的预算，也就是质量预算。

Because the science team, we had a certain budget, a mass budget.

这是我们被允许从洁净室取出并进行分析的样本量，一旦取出，样本就实际上被污染了。

This is the amount of sample we're allowed to take out of the clean rooms and analyze, and it becomes effectively contaminated at that point.

整个任务和NASA决定将大约70%的样本保留用于长期保存和未来分析。

The mission as a whole and NASA decided that they were going to save about 70% of the sample for long term curation, future analysis.

一个很好的例子就是阿波罗样本。

A great example of that is the Apollo samples.

对。

Right.

除了那个家伙偷走的所有样本。

Except for all the ones that that guy stole.

抱歉，你继续说。

Sorry, go ahead.

但最近有一批从未开启过的阿波罗核心管被分析了，因为我们都愿意等待六十年，直到技术和分析方法得到提升。

But a bunch of like new Apollo core tubes that had never been opened were recently analyzed because, you know, we had the patience to wait sixty years for technology and analysis techniques to improve.

他们能够完成一些在70年代根本不可能实现的惊人工作。

They were able to do amazing things that would have never been possible back in the and 70s.

所以情况也是一样。

And so same thing.

许多其他的塞勒斯·斯特赖克样本都被保存下来，留给未来的世代。

A lot of the other Cyrus Strike samples are stored for future generations.

所以我们有一个预算。

So we had a budget.

我想到的一个绕过这个预算的方法是，我们能否在保管设施内、在洁净室中、在存放样本的充满超纯氮气的箱子内进行测量。

One of the ways that I decided we could get around that budget was if we could do measurements in the Curation facility, in the clean rooms, in the boxes that are purged with ultra pure nitrogen where the samples are actually stored.

这基本上是一种非侵入性的测量技术，让你能够了解样本的某些特性，而无需将其计入我们的配额。

So basically a non invasive measurement technique that allows you to learn something about the sample without actually counting it against our, you know, without having to put it on our tab.

对，没错。

Right, right.

基本上就是这样。

Basically.

所以我们增加了一台三维扫描仪，这是一种叫做结构光扫描仪的设备。

And so we added a three d scanner, which is something called a structured light scanner.

它就像一对立体摄像头，将一个微小的图案投射到样品上，从而可以创建三维模型。

It's like a stereo pair of cameras and it projects a little pattern onto the sample and you can create three d models that way.

因此，样品一直留在手套箱内，我们只是通过窗口进行扫描，并可以手动旋转样品。

And so the sample stayed inside the glove box and we just scanned through the window and you're able to rotate the sample manually.

工作人员通过手套箱上的手套口伸入，旋转样品，扫描，再旋转，再扫描。

The people reach through like the little glove ports, rotate the sample, scan, rotate, scan.

因此，对于大约20个最大的颗粒，我们在从未将它们移出手套箱的情况下制作了三维模型。

And so with about 20 of the largest particles, we made three d models without ever removing them from the glove box.

此外，他们还有称重设备，可以在手套箱内称量样品，我们就这样获得了密度值。

And then they have mass balances, you know, to weigh the samples inside the glove boxes, and we got density values that way.

所以这是我们最初的线索。

So that was our first hint.

我们观察到了密度的差异。

We saw a range of densities.

我们实际上发现这些颗粒看起来像地表上的巨石。

We actually saw that the particles looked like the boulders on the surface.

我们看到了一些非常尖锐的，也看到了一些更棱角分明、块状且几何感强的颗粒。

We saw these ones that looked really jagged, and we saw these ones that looked more angular and blocky and geometric.

我们立刻发现，这些颗粒的密度不同。

And right away we found, hey, these have different densities.

这正是我们所预测的。

That's what we predicted.

好吧，我认为我们走在正确的道路上。

All right, I think we're on the right track.

这部分工作只是为了确认：我们是否得到了在地表上看到的物质？

Part of this is just like confirming, did we get the stuff we saw on the surface?

这些样本是否能代表小行星全球范围内的情况？

Like, is this representative of what we saw globally on the asteroid?

结果发现，是的，看起来这确实具有代表性。

And it was like, yeah, it looks like this is representative.

这真是太令人兴奋了。

That's really exciting.

这将帮助我们决定哪些样本要放在我们的样品台上并取出分发给科学团队。

And that's going to help us decide which samples we do want to put on our tab and take out and distribute to the science team.

因此，我们有一个完整的筛选过程，挑选出我们称之为感兴趣岩石（SOIs）的石头。

So there's this whole down select process where we picked stones of interest or SOIs as we call them.

每样东西都得有个缩写。

Everything has to be an acronym.

所以，我们有这些SOIs，对它们都测了密度值，然后从那里开始筛选。

So, you know, we had these SOIs and we had density values on all them and we started down selecting from there.

我们还尝试在洁净室中直接测量孔隙率。

We also tried to directly measure porosity in the clean room too.

我们建造了一种叫做气体比重计的设备。

We built this device called a gas pycnometer.

这与梵蒂冈天文台的陨石馆长，鲍勃·麦基神父合作完成。

This was in partnership with the curator of meteorites from the Vatican Observatory, brother Bob Mackie.

向Bob致敬。

Shout out to Bob.

我会发一个链接给你，你可以稍后听。

I'll send you a link to this so you listen later.

嗨，Bob。

Hi, Bob.

Bob是这方面的专家，他的方法很像阿基米德原理：当你有一体积的水，把一个固体放进去，观察排开多少水，就能知道这个物体的体积；同样的道理，我们可以用气体，借助理想气体定律来实现。

So Bob is an expert in this measurement that it's much like the Archimedean principle where, you know, if you have like a volume of water and you drop a solid in and you see how much water is displaced, know, the volume of the thing you dropped in there, you can do the same thing with gas using the ideal gas law.

因此，我们设计了一个设备，连接到手套箱内，以非污染的方式进行这种测量。

And so we built a device that attached to the glove box chamber to do this measurement in a non contaminating way.

不幸的是，我们的测量计划因样品的意外特性而受阻，因为我们使用氮气进行测量，部分原因是这是唯一被允许的气体。

Unfortunately, our measurement plans were foiled by the unexpected nature of the sample because we used nitrogen as the gas to do this measurement, partly because we were required to do so.

这是我们被允许使用的唯一气体。

This was the only gas we were allowed to use.

我们得到的结果非常异常。

And the results we got were super wonky.

这些数字毫无意义，我们最终发现这些样品就像在呼吸气体，气体基本上吸附在了表面。

The numbers didn't make any sense, and we eventually found that the samples, they were like breathing in the gas, and it was like basically absorbing onto the surface.

它们具有巨大的内表面积，气体基本上从方程式中消失了。

They had tons of internal surface area and the gas was basically disappearing from the equation.

这是在沉积，至少这是我们目前的主要假设。

It was depositing at least this is our leading hypothesis.

我认为鲍勃仍在努力理解，但气体基本上从方程式中消失了，结果完全说不通。

I think Bob's still working to understand, but the gas was basically disappearing from the equation and the results didn't make any sense.

因此，很遗憾，尽管我们尽了最大努力，在样品的初步筛选阶段仍未能获得直接的孔隙率测量数据。

So unfortunately, despite our best efforts, we did not get direct porosity measurements during this initial triage phase of the sample.

这本来会非常有用，所以我们不得不尝试其他方法来实现。

That would have been super useful, but so we kind of had to, you know, try other ways to do it.

明白了。

Got it.

你有没有亲自打开手套箱，亲手处理过这种材料？

Did you ever actually get to like put your hands on the glove box and like handle the material yourself?

我不这么认为，不，在NASA约翰逊航天中心不行。

I don't think, no, not at NASA Johnson Space Center.

那里对谁可以把手伸进手套箱有非常严格的规定。

They have very strict rules there about who's allowed to put their hands in the glove box.

但我经常在房间里，能够，你知道的，看看这些样本，是的。

But I was in the room pretty frequently and got to, like, you know, look at the samples Yeah.

大概几英尺远，不过对于分发给团队的那些样本，我最终确实亲手处理过。

Like a couple feet away, which With is pretty the samples though that were distributed to the team, I eventually did handle the samples.

明白了。

Got it.

比如其中一些，你知道，我就在我的实验室里处理，那时候就不必再把它们放在手套箱里了。

Like some of them, you know, I worked with right in my lab, and at that point you don't have to keep them in a club box anymore.

所以有些样本，你知道，用镊子夹着，随便怎么处理都行。

And so some of them, you know, you handle with tweezers and just kind of do your thing.

不错。

Nice.

是的。

Yeah.

我就是那种书呆子，喜欢在沙漠里或外出时去捡石头。

I'm I'm the kind of nerd that like, I'll rock hound when I'm out in the desert or out and about.

我会找到一块有趣的石头，然后说：‘真酷。’

I'll find a cool rock and be like, neat.

然后我会把它带回家，放在我的石头架上。

And I'll, you know, take it with me, put it on my rock shelf.

是的。

Yeah.

我有一个石头架。

I have a rock shelf.

但我经常想，天啊，这块石头基本上一直躺在那里，经历了漫长的时间，直到我走过并把它捡了起来。

But I always I often think like, man, this rock has been sitting there for basically all of time Yeah.

直到我走过并把它捡了起来。

Until I walked along and picked it up.

你得亲手拿起来，你知道的，现在

And you got to, you know, hand Now

这是杰克的石头吗？

it's Jack's rock?

基本上是的。

Basically.

好吧，你得处理一些材料，同样是那种感觉，但规模是太阳系级别的。

Well, you got to handle some material that same thing, but on a on a solar system scale.

对我来说，这简直太疯狂了，而且真的、真的酷。

Like, it's just it's kind of wild to me, and it's really, really cool.

我记得第一次进去时近距离看到这些样本，那种时刻让人根本忍不住一直傻笑。

I remember going in for the first time and seeing the samples up close, and it's like one of those moments where it's impossible not to just be grinning like an idiot the whole time.

和我一起在里面的其他人，一些其他科学家，也是第一次来，我们全都光芒四射。

And the other people that were in there with me, some of the other scientists, it's their first time too, and we were all just like, just glowing.

是啊，你怎么可能不呢？我们穿着巨大的防护服，只能看到眼睛。

Yeah, how could you In our giant bunny suits, so you could only like see our eyes.

你看到每个人都带着微笑的眼神。

You see everyone smizing.

是的，没错。

Yeah, exactly.

对，对。

Yeah, yeah.

那真的非常令人兴奋。

That was really exciting.

而且让人震惊的是，实物竟然这么黑，因为你在航天器拍摄的照片里看到的样本总是被放大并调亮，以便看起来更美观，但近距离一看，这些东西黑得像木炭一样。

And it was shocking, like how dark the material was in person because the images you see taken by the spacecraft, they're always blown up and brightened to make them look really nice, but up close, the stuff is black as charcoal.

哇。

Wow.

是的。

Yeah.

好的。

Okay.

要弄清楚正是内部裂缝的惊人程度造成了这里的差异，即问题的根源。

To figure out that it was in fact the insane level of of internal cracks that was the discrepancy here, the cause of discrepancy.

你们不得不求助于日本的一个团队，他们使用锁相热成像技术。

You guys had to go to a team in Japan that did lock in thermography.

是的，有两项测量对这篇论文至关重要。

Yeah, there were two measurements that were really critical to this paper.

其中之一是称为锁相热成像的热流测量，其目标是直接测量样品的热惯性。

One of them was this heat flow measurement called lock in thermography, where the goal there was to directly measure essentially the thermal inertia of the samples.

同样的技术也曾应用于小行星龙宫在隼鸟二号任务中带回的样本，而龙宫和贝努有许多相似之处。

And the same technique had been applied to the samples brought back from asteroid Ryugu in the Hibiscus-two mission, and Ryugu and Bennu have a lot of similarities.

因此，我们很期待进行一次直接的对比。

So we were excited to do an apples to apples comparison.

这种技术基本上是用激光周期性地加热样品表面，也就是说激光是脉冲的。

This technique basically you heat the surface of the sample with a laser periodic, so the laser is pulsing.

你

You

别说了。

don't say.

这预示着我的职业道路。

It foreshadowing was for my career path.

真的。

For real.

这基本上会在表面产生热波纹，你知道的，如果你用热成像相机拍摄的话。

And that basically creates like thermal ripples across the surface, you know, if you image it with a thermal camera.

真的吗？

You don't say.

这些热波纹的周期、间距和时间特性，你可以计算出样品的热扩散率和热惯性。

And the period of those thermal ripples and like the spacing and timing of them, you can calculate the thermal diffusivity and thermal inertia of the samples.

因此，这项技术被应用于我们认为可能对应小行星表面那两块巨石——非常棱角分明的和非常粗糙崎岖的——的两类不同颗粒上。

So this technique was applied to a few different particles from the two categories that we thought, you know, we were hypothesizing map to those two boulders on the surface of the asteroid, the really angular ones and the really rough jagged ones.

我们得到的热惯性值远高于我们在小行星表面测得的值。

And we got thermal inertias that were way higher than what we had gotten on the surface of the asteroid.

所以我们想，这到底是怎么回事？

So we're like, okay, what's going on here?

小行星告诉我们热惯性很低，因此它们可能是多孔的，但当我们测量时，却得到了很高的热惯性，类似于其他陨石。

The asteroid was telling us that thermal inertia is low, and therefore they may be porous, but when we measure them, we get a high thermal inertia, kind of like other meteorites.

隼鸟2号团队在龙宫样本上也得到了相同的结果。

And the Hibusa2 team had gotten the same result with the Ryugu samples.

因此，我们花了一些时间仔细思考这个问题。

And so this took some pondering for a while.

我逐渐意识到，这种技术实际上是在极小的尺度上探测样本。

And I came to realize that this technique, it's probing the samples at a really small scale.

因为那些热波纹只扩散出几百微米。

Like it's only those thermal ripples only emanate out a few 100 micrometers.

非常小的测量区域，小于一毫米。

Very small spot sizes, smaller than a millimeter.

所以，这就像在几根头发丝的宽度尺度上测量材料的特性，真的是这样。

So, you know, it's like measuring the properties at length scales of like a few hair widths, literally.

是的，头发大概是10微米左右吧？

Yeah, hair's what, like 10 microns or something?

我忘了。

I forgot.

我不是研究头发的专家。

I'm not a hair scientist.

抱歉，老兄。

Sorry, dude.

你跟我说过你是研究头发的专家。

You told me you were a hair scientist.

我以为我听完之后能拥有一头浓密的秀发呢

I thought I was going to have an awesome head of hair after

我帮不了你啊，兄弟。

Can't help you, man.

另一个非常关键的测量是被称为X射线计算机断层扫描的技术。

The other really critical measurement was one that we call x-ray computed tomography.

它被用于医疗领域。

It's used in medical field.

它已经使用一段时间了。

It's been used for a while.

它就是他们所说的CAT扫描或CT扫描。

It's like what they call a CAT scan or a CT scan.

它本质上是一种三维X射线。

And it's literally a three d x-ray

就像那个旋转的磁体，用液氦冷却的疯狂机器，不，会把你吸进去

of It's like the spinning magnet, helium cooled, crazy machine that would No, suck out your

它不需要用液氦冷却。

it doesn't have to be helium cooled.

这些设备，你知道的，有的大小就跟那边那个小家具差不多。

These devices are, you know, they can have one like the size of that little piece of furniture over there.

你知道吗，如果你去过机场，而且不用把电脑从包里拿出来，那就是同样的扫描仪。

You know, actually, if you've been to the airport where you haven't had to take your computer out of a bag, it's that exact scanner.

好的。

Okay.

这是一种三维计算机断层扫描仪，能够进行三维X光扫描，可以逐层扫描整个三维结构。

That's a three d, that's a computer tomography scanner where it does a three d x-ray, and they're able to basically sweep through the three d, like do slices.

是的。

Yeah.

可以查看你包内不同深度的物品，比如：这是笔记本电脑，这是上面的东西，这是下面的东西。

And look at different depths through your bag and be like, all right, here's the laptop, and here's the stuff on top of it, here's the stuff below it.

并确认所有物品都不是炸弹之类的危险品。

And verify that everything, know, none of it's a bomb or whatever.

不管你喜欢带什么乘飞机。

Whatever love it is

你喜欢的那些机器。

that you like to fly with.

我喜欢那些机器。

I love those machines.

是的。

Yeah.

使用的是完全相同的技术，只是在小得多的尺度上进行测量。

Exact same technology, just measuring things at a much, much smaller scale.

所以NASA约翰逊航天中心，这是约翰逊航天中心的斯科特·埃克利，向斯科特致敬，这些测量结果非常出色。

So NASA Johnson Space Center, this was Scott Eckley at Johnson Space Center, shout out to Scott, these measurements were amazing.

他测量了数十个最大的颗粒，并且以无污染的方式进行，因此不会计入任何人的限额——他们基本上把这些颗粒封装在这些密闭容器中并进行了包裹。

He measured dozens of the largest particles and they also did it in a non contaminating way, so it didn't count against anyone's tab, where they basically packaged them up in these hermetically sealed vessels and wrapped them.

就像多层包装一样，然后他们能够将容器直接放入仪器中，直接穿透容器壁进行扫描。

It was like multiple layers of wrapping, then they were able to put it in the instrument and scan right through the walls of these containers.

所以这些样本都有自己类似太空服或地球服的保护装置？

So like the samples had their own little like quasi space suits, earth suits?

差不多，是的。

Kind of, yeah.

它们是不锈钢容器，然后用好几层包装袋包裹起来。

They were these stainless steel vessels, and then they wrapped them in several layers of bagging.

是的，整个过程都有一套严格的流程，他们在之前做了大量测试，以确保不会引入任何污染。

And yeah, was a whole process to like and they did a bunch of tests beforehand to verify that there would be no contamination introduced.

所以，他们用了一些模拟样本进行实验，确保样本在处理前后依然保持洁净。

So, you know, they did it with like some dummy specimens and made sure that they came out just as clean as they went in.

这确实是一种非常关键的方法。

And so that was really that was a really enabling method.

这让我们能够观察内部结构。

And that allowed us to look into the internal structure.

正是在这里，我们开始能够绘制出裂缝的分布。

And this is where we started to be able to map out the cracks.

我们注意到，两种不同类型的样本——角状的和我们所说的丘状或非常粗糙的样本——它们的裂纹网络看起来截然不同。

And we started to notice that the two different sample types, the angular and what we call the hummocky or the really rough ones, crack networks looked really different.

然后我意识到，这些锁相热成像测量的空间尺度足够小，当你观察一块岩石并放大时，如果这里有一条裂缝、那里也有一条裂缝，热成像测量可能正好落在它们之间的位置。

And then I realized that those lock in thermography measurements are at a spatial scale that is small enough that like if you look at a rock and you zoom in and maybe there's a crack here and a crack here, the thermography measurement could be just right in between them.

这基本上无法捕捉到那些更大尺度裂缝的特征，而这些裂缝对热流和材料的热惯性有着至关重要的影响。

And it's basically not picking up the signature of all those cracks that are at a larger scale can be really influential in dictating heat flow and the thermal inertia of that material.

所以我使用了X射线扫描的数据，能够将这些裂隙网络以三维形式提取出来，作为计算机产物，并通过计算机模型模拟热量在其中的传导。

And so I used the data from the X-ray scans, and I was able to basically extract those crack networks in three d as like a computer product and simulate the heat flow through them with a computer model.

哇。

Wow.

基本上是为了理解这些裂隙究竟在做什么？

And basically to understand like, what are these cracks doing?

它们应该对热流产生怎样的影响？

What should they be doing to the heat flow?

如果你再把这一结果与锁相热成像的直接数据结合起来，基本上把两者融合在一起，就能大致重现我们在小行星上观测到的现象。

And if you then like basically combine that result with the direct lock in thermography result, you basically shove those two together, you can more or less reproduce what we saw in the asteroid.

所以之前我说过，认为这是裂隙和孔隙共同作用的解释，并不是什么疯狂的想法。

And so that's why I said earlier, like the idea that this is a combination of cracks and pores is the explanation was not like it was not like a crazy idea.

困难之处在于如何证明它。

The hard thing was proving it.

是的。

Yeah.

要真正获得能证明这一点的数据非常困难——是的，这些天体确实是孔隙和裂缝并存的，虽然孔隙率可能没有我们原先以为的那么高，大约只有30%，但它们确实布满了裂缝。

And that was really hard to like actually get data that proved, yes, it is a combination of, yes, these things are porous, maybe not as high as we thought, they're porous, they're like 30% porosity, but they're also just really cracked.

这就是最合理的解释。

And that's that's the explanation.

所以它们可能没有我们想象的那么海绵状或蓬松。

So they may not be as spongy or as fluffy as we thought.

如果你用航天器撞击它们，它可能会稍微压实一点，但并不会达到50%的孔隙率。

So if you crash into one with your spacecraft, it may compact a little bit, but it's not 50% porous.

它不会完全被压扁。

It's not going to just compact down.

是的。

Yeah.

因此这对行星防御有重要影响。

So there are implications there for planetary defense.

如果我们发射动能撞击器，孔隙率会起到关键作用。

If we send a kinetic impactor, that porosity matters a lot.

这就是为什么我希望正在听的你们会想：我为什么要关心这个？

And that's one of the reasons like I hope that people who are listening this, you know, you're probably like, why do I care?

到目前为止，你在这档播客里已经说了五十万次多孔性了。

You've said porosity 500,000 times on this podcast so far.

这正是我们关心它的原因之一，因为撞击一个物体时，撞上海绵和撞上砖块的差别巨大。

That's one of the reasons we care about it, because if you crash into something, it's know, there's a big difference between crashing into a sponge and crashing into a brick.

是的。

Yeah.

而且

And

情况就是这样。

that's kind of like that.

你们会希望如何使这类天体偏转。

How you are going to want to deflect something like that.

如果它能吸收撞击器带来的大量惯性、动量或作用力，那么你们就需要更大的撞击器，或者采用其他方法

Like, if it's if it's going to absorb a significant amount of that inertia, momentum, I don't know, force from the impactor, then you're going to need a bigger impactor or some other method or

或者用别的方法，是的。

Or a different method, yeah.

所以这是其中很重要的一部分。

So that's a big part of it.

其中很大一部分工作是确保我们能将样本与小行星表面所观测到的内容对应起来，并让热惯性数据与我们观测到的角状颗粒和非常粗糙的颗粒相吻合。

A big part of it was just making sure that we could map the samples back to what we saw on the surface of the asteroid and getting those thermal inertias to line up where we had the angular sample particles and the really rough particles.

我们发现，这些热惯性数据与我们对小行星表面的估算结果是一致的。

We found that those thermal inertias were consistent with what we estimated on the surface of the asteroid.

因此，这进一步证明了这些样本确实是与表面特征一一对应的。

So that was more evidence that like, yeah, these are actually mapped one to one.

我们确实拥有小行星表面两种巨石类型的样本，这极大地帮助我们把事情放在更清晰的背景下理解。

Like, we do have pieces of the two boulder types on the surface of the asteroid, so that was really helpful to just put things into context.

然后，当然，这也帮助我们向前推进，更好地理解整体情况，比如：我们该如何解读未来的遥感数据、望远镜数据？

And then, you know, yeah, helping us moving forward to understand the big picture, like, how do we interpret remote sensing data moving forward, telescopic data?

我们观测到较低的热惯性。

We see a low thermal inertia.

现在我认为我们在做解释时会更加谨慎。

Now I think we're going be a little more careful in making interpretations.

你知道，你不能盲目地去做。

You know, you can't just do it blindly.

你需要考虑光谱类型，如果这是一个碳质小行星，并且你观测到低热惯性，我认为它很可能是布满巨石的。

You'll need to consider like what is the spectral type and if it is a carbonaceous asteroid and you see a low thermal inertia, I think it is highly likely that it could be bouldery.

这些高度碎裂且多孔的巨石，由于各种原因，可能在这种类型的小天体上是不可避免的。

It's just that these types of heavily cracked and porous boulders, they may be kind of an inevitability on these types of objects for various reasons.

这太迷人了。

That's fascinating.

那么，所有这些信息如何改变或影响你对AstroForge目标小行星的看法，无论是在我们尝试前往、着陆，甚至在着陆过程中？

So how does all of this information change or inform how you think about AstroForge's target asteroids before we even attempt to, you know, get to one or land on one or maybe even as we do?

还是说并没有影响？

Or does it?

是的，我正在思考。

Yeah, I'm trying to think.

我可以说完全不是。

I could just say not at all.

不。

No.

我的意思是，不，这个回答很合理。

I mean, no, that's a fair answer.

我认为，尽管材料会非常不同，但物理规律是普适的。

I think that so physics are universal, even though the materials are going to be really different.

物理规律是普适的。

Physics are universal.

我们对小行星贝努的了解，让我们认识到了小行星表面重要的地质过程。

And what we've learned about asteroid Bennu has taught us about processes that are important on asteroid surfaces.

导致那些巨石形成并出现严重裂隙的因素，比如热疲劳、风化作用以及物质结合的方式，都是如此。

The things that were responsible for creating those boulders and making them really cracked are things like thermal fatigue and processing and just the way that the material is held together.

如果我们到达一个金属小行星，发现它被一层风化层覆盖，我认为一旦我们着陆，这些物质肯定会四处飞溅。

If we get to, for example, a metallic asteroid and we see that it is covered in a regolith layer, I think we know that if we touch down on the surface, that stuff is going to fly everywhere now.

对。

Right.

从采样中。

From the sample collection.

对。

Right.

如果我们能在航天器上搭载热学仪器，根据我们所观察到的材料类型，我认为我们现在能更好地解读这些数据。

If we are able to bring a thermal instrument on our spacecraft, depending on the type of material that we see, I think we're going to do a much better job now in interpreting that data set.

差不多吧，我要说，可惜没有那种完美的《星际迷航》式材料分析设备。

Almost yeah, I'll say it is tragic that there is no like perfect Star Trek material analyzing device.

就像一个按钮。

Like, button.

是的。

Yeah.

它能直接告诉你所有你需要知道的信息。

That just tells you everything you need to know.

每种测量技术都会给你不完整的信息。

Every measurement technique is gonna give you incomplete information.

相机只能告诉你一些事情。

Camera only tells you a few things.

热仪器能告诉你一些信息。

Thermal instrument tells you some stuff.

光谱仪能告诉你一点点。

Spectrometer tells you a little bit.

它们的组合能告诉你更多。

The combination of them tells you a lot more.

所以，仅仅通过这个过程，使用AstroBe在任何地方，我们最初从地球上看它是一个点源，然后我们前往那里，从航天器的角度对其进行环绕观测。

So just doing this, going through this whole process with AstroBe anywhere, we looked at it as a point source from Earth, and then we went there and we orbited it and looked at it from the spacecraft perspective.

接着，我们实际采集了这些材料，将其带回地球，并利用世界上最先进、最尖端的设施来分析和理解我们到那时为止所做的一切观测。

And then we actually took that material, brought it back, and we used the world's most cutting edge, state of the art facilities to analyze and understand all those observations we made up to that point.

这是这个过程中的关键环节，也是我们必须持续进行的事情。

That's a critical part of the process and it's something that we're going to have to keep doing.

每次我们这样做，都会变得更聪明一点，更能更好地解读我们的数据。

And each time we do it, we're going to get a little smarter and know how to interpret our data a little bit better.

所以，我真希望可以说，是的，这解决了我们所有的问题，我们确切知道在金属小行星上会发现什么。

So I wish I could say that, yeah, this solves all our questions and we know exactly what we're going to find on a metallic asteroid.

但不行，还没有什么水晶球可以预知未来。

But no, there's no crystal ball, not yet.

这就是为什么我们必须继续探索这些天体，因为每次这样做，我们都会

That's why we just got to keep going to these objects because each time we do it, we're going

学到大量知识，并且越来越擅长这件事。

to learn a crap load and get better at this.

我一直在想你在这集开头说的那句话，就是：天啊，我们应该多做几次这样的任务。

I I just keep thinking about what you said near the beginning of the episode where it's like, man, we should be doing a bunch of these.

我真的希望我们能早日实现这一点。

Like, I I really wish we can get there sooner rather than later.

这也是为什么我如此兴奋地来到AstroForge的原因——我们即将向这些天体发射大量探测器，去探索那些我们现在还完全不知道答案的问题。

And I'm that's part of the reason why I'm so excited to be here at AstroForge is like we are going to be sending a bunch of these probes to a bunch of these bodies and figure out a whole bunch of stuff out that we just don't know the answer to right now.

是的

Yeah.

我的意思是，这也是我在这里的主要原因之一。

I mean, that's one of the main reasons I'm here too.

我只是想看到更多的小行星。

I just wanna see more asteroids.

当然了。

Heck yeah.

根据我们迄今为止的对话，我想我知道这个问题的答案。

I think I know the answer to this based on our our conversation thus far.

但你会对2015年的自己，也就是刚读研的你，说什么呢？关于小行星科学和小行星采矿到2026年会发展到什么地步？

But what would you tell your 2015 grad student self about where asteroid science and asteroid mining would be by 2026?

你会相信未来的自己吗？

And would you believe future you?

我想我会相信的。

I think I think I would believe it.

因为在2015年，

Because in 2015,

我记得曾经有人来自行星资源公司来访，那是上一代小行星采矿和小行星资源公司的代表。

I remember we had a visit from someone that worked for planetary resources, which was one of the previous generation of asteroid mining and asteroid resource companies.

对。

Right.

我记得当时被深深激励了，觉得这真是太酷了。

And I remember being really inspired by that being like, that's freaking cool.

我想做这样的事。

And I want to do that.

但我当时的想法可能还不够有野心。

But I think I was kind of thinking about it almost I wasn't ambitious enough.

我记得那时想着，我想成为一家小行星采矿公司的热分析专家。

I remember at the time thinking, I want to be the thermal analysis expert for an asteroid mining company.

但如果能回到过去，我想我会说，这很好，但不妨梦想得更大一些。

But if I could go back, I think I would have said, that's great, but dream even bigger.

因为你不必只局限于这种单一的专门技术。

Because you don't have to stop just at like this one niche technique.

去追求整个领域吧。

Like, go for the whole thing.

不要只分析温度。

Don't just analyze temperature.

分析小行星的方方面面。

Analyze everything about the asteroid.

总有一天你会分析小行星的样本，之后你还会去开采小行星。

You're going to analyze samples from an asteroid someday, And after that, you're going to go and mine asteroids.

太棒了。

So Awesome.

我觉得如果当时听到这些话，我会非常兴奋。

I think I would have been pretty stoked to hear that.

也许会有点紧张，但那没关系。

Maybe a little intimidated, but that's fine.

我太喜欢了。

I love it.

好吧。

All right.

那么，还有什么我还没提到、或者你希望在进入邮件环节前讨论的吗？

Well, is there anything I haven't hit or or that you want to hit before we move on to mailbag?

我的意思是，我喜欢这种更深入的讨论。

I mean, I like these more detailed discussions.

我们的观众应该也喜欢。

Our audience hopefully does as well.

我制作航天相关内容并发布到网络的全部经验是，人们欣赏你不以居高临下的态度对待他们。

At least my entire experience making content about spaceflight and putting it on the internet is that people appreciate it when you don't talk down to them.

人们欣赏你直接坦率地告诉他们真相，向他们传递信息，因为人们真的想学习。

People appreciate it when you just straight up tell them what's up and like inform them because people want to learn.

所以，如果我漏掉了什么，或者你有什么想法还没提到，想在我们用邮件环节收尾之前补充的，尽管说吧。

So if there's anything I've missed or or haven't thought of that you want to hit before we keep before we sort of put a bow on things with mailbag, by all means, be my guess.

没有。

No.

我觉得我已经在这上面说得够多了。

I I think I've I think I've maybe talked enough on this.

没有。

No.

你确实应该多说。

You do.

不过我还是很感谢这个机会。

I appreciate the opportunity, though.

对于坚持听到现在的人，谢谢你们的收听。

And for those who have stuck with it, thank you for listening.

如果你们对这项研究有任何问题，欢迎给我发邮件。

And if you do have questions about the study, feel free to email me.

是的。

Yeah.

Andy@AstroForge.com。

Andy@AstroForge.com.

实际上，你完全可以这么做。

That's actually you can totally do that.

你可以直接去做一些事情。

You can just do things.

你可以直接对小行星进行热分析。

You can just do thermal analysis on asteroids.

这通常适用于任何科学出版物。

And that's usually true for like any scientific publication.

通常，作者们都很乐意收到问题。

Usually the authors are thrilled to receive questions.

太棒了。

Love that.

我真的很喜欢，科学太酷了。

I really like science is so cool.

我真是个极客。

I'm such a nerd.

好吧。

Alright.

我们进入邮件箱环节吧。

Let's jump into Mailbag.

再次提醒，如果你有问题，可以给安迪发邮件。

And again, if you have questions, you can email Andy.

你也可以把问题发送到 mailbag@astroforge.com，或者在本视频下留言，或者在推特上@我们——你知道的，互联网就是这么运作的。

You can also send your questions to mailbag@astroforge.com or comment on this video or tweet at us or what you know how the Internet works.

如果你有问题，请尽管提问，因为我们喜欢回答问题。

If you have questions, ask them, please, because we like answering.

这是来自托马斯的一个问题。

Here's one from Thomas.

岩石中的裂缝解释了热惯性不匹配的现象。

The cracks in the boulders are what explained the thermal inertia mismatch.

这意味着这些岩石基本上在自行碎裂吗？

Does that mean the rocks are basically falling apart on their own?

也就是说，你理论上只要出现，小行星就已经被预先压碎，可以直接用了？

Like, could you theoretically just show up and the asteroid is pre crushed and ready to go?

是的，它们确实在随着时间推移自行分解，这么说吧。

Yeah, they are breaking down over time, you know, on their own, so to speak.

我们认为一些裂缝非常古老，可能源自母体——也就是贝努的前身，因为我们看到了矿物沉积物。

We think some of the cracks are very old, like from the parent body, the precursor to Bennu, because we see like mineral deposits.

我就不深入细说了，但我们有证据表明其中一些裂缝是古老的。

I'm not going to get into it, but we see evidence that some of them are old.

但我认为有些裂缝显然是新近形成的，或者一直在持续发展。

But I think some of them are definitely newer or have been developing over time.

造成这些裂缝的可能主要有两种过程。

There are two main processes that are probably making the cracks.

其中之一是微陨石撞击。

One of them is micrometeorite impacts.

所以，来自尘埃、沙粒、小石子，甚至更大的微小撞击体，会逐渐磨损、施加应力，并在这些巨石中长期形成应力裂缝之类的问题。

So small impactors from, you know, moats of dust, grains of sand, pebbles up to, you know, anything larger are gradually just whittling away and stressing and, you know, creating stress fractures and things like that in these boulders over time.

但还有一种被动过程，我们称之为热疲劳：数百万年、数十亿年来，这些材料反复经历加热和冷却，每次受热膨胀、冷却收缩，这种反复的热胀冷缩会导致裂缝扩展。

But there's also a passive project that we a passive process, sorry, that we call thermal fatigue, where the actual heating up and cooling down over and over for millions, billions of years, it thermally stresses these materials where each time it heats up, it expands and contracts, expands and contracts, and that can create crack propagation

这就像混凝土人行道开裂的情况一样。

over It's like the same thing that cracks like a concrete sidewalk or what have you.

如果不在上面刻出缝隙，它就会反复受热、冷却、再受热、再冷却，最终就会开裂。

If they don't put the grooves in there, like it's going to heat up and cool down and heat up and cool down and eventually crack.

这是其中一种过程。

That's one of the processes.

但在地球上，还有树根。

On Earth, though Also roots, tree roots.

树根和

Roots and

别让我的类比变得不准确，而且

Don't make my analogy less And

在寒冷地区，水和冻融作用才是真正的破坏者。

in areas where it's cold, water and frost wedging are the real bad.

哦，是的。

Oh, yeah.

冻融作用。

Frost wedging.

我从小在东北长大，那里的道路根本撑不住。

I grew up in the Northeast, and the roads could not survive.

是的，我信。

Yeah, I believe it.

是的，热疲劳。

Yeah, thermal fatigue.

这在小行星表面曾被研究过，我们观察到巨石上有大量热致裂纹的证据，现在正在对返回的样本进行研究。

This is something that was studied on the asteroid surface where we saw lots of evidence of thermally induced fractures on the boulders and it's being studied now in the return samples.

我的同事杰米·马拉罗正在撰写一篇关于这方面的论文。

My colleague Jamie Malaro is working on a paper on that.

实际上，她的论文目前正在审稿中，她做了微观尺度的模拟，并将其与我们观察到的裂缝进行对比，发现有大量的有力证据表明，这些裂缝大多是由热胀冷缩造成的。

Actually, think her paper is in a review right now where she did a microscale model and compared that to the cracks that we see and found that like there's a lot of strong evidence that a lot of those cracks were created by thermal expansion and contraction.

太酷了。

So cool.

嗯，它们可能随着时间的推移在自行分解。

Well So, yeah, they're probably breaking down on their own over time.

是的。

Yeah.

我只是觉得，真希望能快进到深空二号靠近它的目标（无论最终是哪一个）的那一刻，我们可以坐下来，深入探讨我们学到的每一件事。

I'm just like, I wish I could hit the fast forward button to of the point where Deep Space two is pulling up next to its target, whichever it ends up being, and we can sit there and and nerd out super hard about all the things that we're learning.

我非常期待那一刻。

I'm I'm very excited for that.

那一定会很棒。

That's gonna be amazing.

好。

Cool.