Robert Frost 在quora上有关航天的回答收集(一)

【Robert Frost ,Instructor and Flight Controller at NASA,此贴收集了他的一些短回答】

HTV-7离开了ISS HTV-7 Departs ISS

This morning we said goodbye to the Japanese cargo vehicle HTV-7. Forty-one days ago it berthed to the ISS, delivering tons of cargo including new payload experiments and new lithium ion batteries to replace the ISS’s aging nickel hydrogen batteries.

今天早上(2018年11月8日),我们告别了日本货运载具HTV-7。 四十一天前,它停靠在国际空间站,运送了数吨货物,包括新的有效载荷实验和新的锂离子电池,以取代国际空间站老化的镍氢电池。

This was my third HTV mission. It is my favorite of the U.S. Segment cargo vehicles. It is always a pleasure to work with the excellent Japanese flight control team. The vehicle behaved beautifully; I don’t think we wrote a single anomaly report against it.

这是我的第三次HTV任务。 这是我最喜欢的美国段货运载具。 与优秀的日本飞行控制团队合作总是很高兴。 载具表现出色; 我认为我们不用编写它的任何异常报告。

HTV-7’s mission isn’t over, yet. It will remain in orbit for three more days and then after it has performed its re-entry burn, it will jettison an experiment called the HSRC (HTV Small Re-entry Capsule). That capsule, about the size of an Ottoman, contains a canister containing ice packs and in the middle of those ice packs is a container of specimens from experiments from the Japanese ISS module (the JEM). The experiment is to see if this is an effective way to get samples from the ISS to a laboratory in Japan in less than four days (before the ice melts). The HSRC will plunge through the atmosphere, protected by its heat shield. It will land in the ocean off the coast of Japan and hopefully be quickly found and picked up by a boat.

HTV-7的任务尚未结束。 它会继续在轨道上停留三天,然后再进行再燃烧,然后将抛弃称为HSRC( HTV Small Re-entry Capsule ,HTV小再进入舱)的小舱。 该舱大约相当于一个 Ottoman 沙发的大小,里面装有一个装有冰袋的罐,在这些冰袋的中间是一个容器,该容器是来自日本ISS模块(JEM)的实验样品。 实验是为了如果要在四天内冰块融化前从国际空间站送到日本实验室,这是不是个有效的方法。 HSRC将在其隔热罩的保护下跳入大气层。 它会降落在日本沿海的海洋中,希望能很快被船发现并捡起。

Over the last couple of days, the crew has assembled this HSRC and bolted it into the opening where the HTV hatch was. Watching them perform that work reinforced the belief I’ve long had that the most essential set of skills needed by astronauts are those held by mechanics.

在过去的几天中,机组人员组装了此HSRC,并将其固定在HTV舱口所在的开口处。 看着他们完成这项工作,就强化了我一直以来的信念,即宇航员所需的最基本的技能是机械师所掌握的技能。

The capsule has an ablative heat shield, a tiny nitrogen gas reaction control system, a parachute system, and a locational transmitter.

这个舱具有烧蚀隔热罩,微小的氮气反应控制系统,降落伞系统和定位变送器。

Another thing that is different about this HTV mission is that it is going home without its EP (External Pallet). The EP is the large white thing shown in the center of the HTV in this picture.

与其他HTV任务不同的另一件事是,它没有EP( External Pallet,外部托盘)就可以回家。 EP是这张图片中HTV中央显示的白色大物体。

The EP is used to deliver payloads that will remain outside the ISS and thus not need to go through the hatch. On this mission, the pallet was loaded with those new batteries I mentioned earlier. Unfortunately, the Soyuz anomaly that prevented the next crew from arriving last month prevented us from accomplishing the EVAs to install those batteries. The HTV has a limited lifetime on orbit and there are other scheduled vehicles that need its berthing port, so rather than keep the HTV up there significantly longer, it is going home and the EP remains attached to the outside of the ISS.

EP用于传送将保留在ISS外部且,因此无需舱口增加额外有效载荷。 在执行此任务时,托盘上装有我之前提到的那些新电池。 不幸的是,联盟号的异常阻止了下一个机组人员上个月的到来,使我们无法完成EVA来安装这些电池。 HTV在轨道上的寿命有限,并且还有其他预定的载具需要其停泊端口,因此与其让HTV长时间停留在那里,不如将其返回家中,而EP仍附着在ISS的外部。

There is no rest for my group, the next cargo vehicle, the Cygnus NG-10 is scheduled to launch on November 15 and will reach ISS on the 18th.2.5k views · 

我的团队没有休息,下一辆货运载具Cygnus NG-10计划于11月15日发射,并将于18日到达国际空间站。

【博主吐槽:空间站的日常。另外我还以为KSP中小绿人把电池安在舱外是黑科技,原来人类也这么干啊】

@ Ben Brown

JAXA tweeted these images of the crew working on the HSRC…

JAXA在推特上发表了一些图片,来说明宇航员如何在HSRC上工作

哈勃望远镜如何避免被碎片撞到?它会自己算出碎片的路径?还是地面团队会协助哈勃望远镜?How does the Hubble Telescope avoid hitting space debris? Does it automatically configure its path to account for debris comings its way, or is someone on the ground constantly looking after it?

It doesn’t. It just takes the hits.

哈勃望远镜没有避免,只能承受这些碎片撞击。

In 1999, during the third Hubble servicing mission (STS-103), the crew took a series of pictures to document the damage to the surface of Hubble. At that time, with less than a decade in space, the Hubble Space Telescope had around 500 impact scars a millimeter or more in size.

1999年,在第三次哈勃维修任务(STS-103)期间,机组人员拍摄了一系列照片以记录对哈勃表面的损坏。 当时,哈勃太空望远镜的空间不足十年,却有大约500毫米或以上的撞击伤痕。

【评论区】

@ Christine Ricks

Do the impacts play a role in determining when the Hubble reaches the end of its usable life? Or is that determined mostly by other factors?

这些撞击是否在哈勃望远镜的寿命上起了决定作用?还是其他主要因素影响着哈勃的使用寿命?

答主答:

Yes, the impacts degrade the solar arrays and can disable equipment.

是的,撞击可以损坏太阳能电池板和其他设备。

@ Will Johnson

Well wouldn’t just a single impact, placed well, disable the viewing ability of the Hubble?

有没有可能,一次恰到好处的撞击就让哈勃望远镜看不到任何东西了呢?

答主答:

sure。

NASA的开普勒望远镜是如何发现180光年之外的行星“HIP 116454b”的?How did NASA’s Kepler find the planet ‘HIP 116454b’ when it is 180 light years away?

This is one of the most famous pictures taken by the Hubble Space Telescope.  The features shown in it are called the Pillars of Creation.

这是哈勃太空望远镜拍摄的最著名的照片之一。 其中的东西我们称为“ 创生之柱 ”。

These gaseous structures are part of the Eagle Nebula.  The Eagle Nebula is 7000 light years away.  The picture was taken by Hubble in 1995.  The Pillars of Creation are believed to have been destroyed by the blast wave of a nearby supernova, 6000 years ago.

这些气态结构是鹰状星云的一部分。 鹰状星云距离我们有7000光年。 该照片是哈勃在1995年拍摄的。据信,“创生之柱”已被6000年前附近超新星的爆炸波摧毁。

We took a picture of something that was destroyed 6000 years before we took the picture.

我们拍摄了一张在拍摄照片6000年前就被销毁的东西的照片。

That was possible because photography is passive.  We don’t send any type of wave or signal or beam towards the object we want to image.  It isn’t like radar where a radio wave is sent out, hits an object and bounces back towards us.  All we have to do with photography (or more precisely spectrography in this case) is open up our sensor and wait for photons to hit it.

这是可能的,因为摄影是被动的。 我们不会向要成像的物体发送任何类型的波,信号或光束。 它不像雷达那样发出无线电波,撞击物体并向我们反弹。 我们与摄影(或在这种情况下更准确地说是光谱学)有关的所有事情都是打开我们的传感器,等待光子撞击它。

The photons that we detected and allowed us to capture the image of the Pillars of Creation left the gaseous structure 7000 years ago.  They were already well on their way towards us a thousand years later when the structure was destroyed.

我们检测到并允许我们看到这样一张图像的光子,在7000年前就离开了那个气体结构。 当结构被摧毁时几千年后,这些光子已经很接近我们的望远镜了。

The same idea applies to the detection of exoplanets such as HIP 116454b.  We detect many of these exoplanets by observing changes in the light we are receiving from a star as the planet passes in front of the star.  That light left the star HIP 116454b orbits 180 years ago and finally just reached our camera sensors.  Those photons were coming towards us regardless of whether or not we wanted to capture them as a photograph.

相同的想法适用于系外行星的探测,例如HIP 116454b。 当行星经过恒星前方时,我们通过观察我们从恒星接收到的光的变化来检测其中许多系外行星。 180年前,那束光离开了HIP 116454b恒星,最后到达了我们的相机传感器。 无论我们是否想将捕获那些光子, 那些光子总是会朝我们这边飞来。

Because all we are doing when we capture an image is capturing photons that traveled from the imaged object to us, we can take pictures of things that are incredibly far away.  In 2011, the Hubble Space Telescope and the Spitzer Space Telescope both captured pictures of a galaxy so far away that it took the photons 13.3 billion years to reach us.  This is a galaxy so old it existed just 400 million years after the Big Bang.

因为我们在捕获图像时,所做的只是捕获代表着那个图像的光子,所以我们可以拍摄到难以置信的物体的照片。 2011年,哈勃太空望远镜和斯皮策太空望远镜都拍摄到了一个遥远的星系的图片,以至于光子需要133亿年才能到达我们。 这是一个如此古老的星系,距大爆炸后仅4亿年就已存在。

【评论区】

@ Aditya Malhotra

Thankyou Robert, but can you explain me how do you come to know that a light coming your way is some 13 billion years old and that far from the source. I mean light is coming from everywhere, and all hubble does is capture them, their photons as you said. They do not have any origin tag with them. So how do you figure that out?
On what basis did you say that that light is coming from 13.3 billion light years away?

谢谢你Robery,但您能解释一下我是怎么知道光已有130亿年的历史,它离源头还很远啊。 我的意思是,光线无处不在,正如您所说,哈勃望远镜所做的就是捕获它们的光子。 但它们不会主动告诉我吗它们从哪里来。 那么,您为什么说该光自来自133亿光年前?

答主

Redshift。红移。

为什么木星上没有可供我们站立的表面?Why doesn’t Jupiter have a surface that you can stand on?

On Earth, we have a rather dramatic transition from gas (our atmosphere) to solid (the Earth’s crust).  That sharp transition creates a medium in which we can easily move through the air but receive enough resistance from the solid that it can support us – we can stand on it.

在地球上,从外太空往地球中心,会经历了从气体(我们的大气层)到固体(地壳)的急性转变。 这种急剧的过渡创造了一种中间地带,我们可以在其中轻松地在空中移动,但会从地表固体中获得足够的支持力来支撑我们站在上面。

On Jupiter there is no such transition.  Instead as we work our way down through Jupiter’s atmosphere it just keeps getting denser and denser.  Eventually the gaseous hydrogen becomes liquid hydrogen.  We keep descending and it becomes denser and denser until that liquid hydrogen becomes a super hot liquid metal.  If we kept descending, we likely would eventually come to a solid core.  But the interior pressure on Jupiter is millions of times greater than on the Earth.  The heat and pressure would have destroyed us and our spacecraft long before we got to that core.  The extreme density of the liquid would have made it impossible for us to even propel ourselves towards the core.

在木星上没有这样的过渡。 相反,当我们沿着木星的大气层向下移动时,大气只会变得越来越密集。 最终,气态氢变成液态氢。 我们不断下降,它变得越来越密,直到液态氢变成超热液态金属。 如果我们继续下降,我们很可能遇到一个坚实的核心。 但是木星的内部压力比地球大数百万倍。 早在我们到达核心之前,热量和压力就已经摧毁了我们和我们的航天器。 液体的极高密度使我们无法到达木星的核心。

【评论区】

@ Nate Waddoups

So, is the term “gas giant” a misnomer? I had assumed that meant is was more gas than solid or liquid, but from that diagram is appears that it’s only gas for a small fraction of the diameter.

那么,说木星是一团“巨大气体”是否是错误的? 我原本以为气体比固体和液体多,但从该图看来,气体只占了很小一部分。

答主回答:

Yes.  They are called gas giants not because they are gas, but because they are primarily hydrogen and helium – which on Earth are gases.

是的,我们把木星叫做“巨大气体”不是因为木星上有很多气体,而是因为木星上有很多氢和氦元素——这两种元素在地球上主要以气体形式存在。

@ Tim Hibbetts

This tells us _what_ is going on, but I’m having trouble seeing just _why_ this is the way it is.

看了您的答案后,我知道木星上面是不可以让人站立的,但我不知道为什么没有形成能让人站立的固体表面。

答主回答:

Because the substances it is made from (primarily hydrogen and helium) don’t form solids.

因为组成木星的主要物质,氢和氦元素并没有形成固体。

@ Tim Hibbetts

So, the heavier elements just didn’t make it out this far? I can dig that.
Thanks!

所以,意思就是木星上形成不了重元素?我知道了,谢谢。

@ Nathan Merrill

They did actually make it out that far, though in lesser quantities.

木星上确实有重元素,但数量较少。

Thing is, think about what happens when you put iron in water; it sinks, right?

想想你把一个铁块扔到水里会发生什么?下沉,对吧?

Well, hydrogen and helium are not very dense at all; iron will, thus, obviously sink right down through it towards the center of the planet. So will any other dense material. This is true of any non-solid object; in a liquid or gas, less-dense materials will settle in towards the middle.

氢和氦密度没有那么大,而铁密度很大,所以会一直下沉到木星的中间,其他比氢和氦密度大的东西也是这样。对于任何非固体对象——在液体或气体中都是如此,密度较小的材料不会向中间沉降。

Because there is so much hydrogen and helium in these planets, all the heavier materials sank right through that into the center of the planet. Thus, we don’t see any of the really heavy elements in their atmospheres because they’re all sunk so deep in the planet we can’t detect them.

由于这些行星中有太多的氢和氦,因此所有较重的物质都通过它沉入了行星的中心。因此,我们在它们的大气层中看不到任何真正重的元素,因为它们都沉入了行星的深处,无法检测到它们。

Indeed, a similar process happened on Earth before it cooled; the reason why many really dense metals are so rare is because they sank down into the core of the planet while it was molten. The core of Earth is made out of iron, nickel, and other very heavy elements, while the crust of Earth has a lot of silicon and carbon, which are a lot less dense than iron. However, the Earth cooled off before it could completely differentiate itself, and thus the Earth’s surface is a mixture of various elements, including heavier elements, whereas there was enough helium and hydrogen and other gasses on the gas giants to completely bury the denser elements inside the planet.

实际上,在地球冷却之前,地球也发生了类似的过程。之所以这么多真正致密的金属如此稀有,是因为它们在熔化时沉入了行星的核心。地球的核心是由铁,镍和其他非常重的元素组成的,而地壳则含有大量的硅和碳,比铁的密度低得多。但是,地球在这些元素完全沉降前就已经冷却了,因此地球表面是各种元素的混合体,包括较重的元素,而木星上巨大的氦气,氢气和其他气体足以将较密的元素完全掩埋在内部星球。

有人在太空中打开过啤酒或者苏打汽水吗?发生了什么?Has anyone ever opened a beer or soda (bottle or can) in space (or vacuum chamber on Earth)? What happens?

Yes.  We have tested Coca-Cola (and Pepsi) in space.  In 1985, we flew special cans from the manufacturers as an experiment aboard the Space Shuttle and in 1996 a Coke dispenser was flown.

是。 我们已经在太空中测试了可口可乐(和百事可乐)。 1985年,作为航天飞机上的实验,制造商制造特殊的罐子让我们带上天,并于1996年又制造了可乐分配器让我们带上天。

Soda in space is a bit problematic.  In micro-gravity, the light gas bubbles won’t rush to the top of the liquid and escape.  They will stay within the liquid.  This means the astronaut will consume significantly more gas drinking a soda in space than one would drinking a soda on the ground.  Drinking a carbonated beverage could be like drinking a foamy slurp.

太空中汽水与地球上的不一样。 在微重力作用下,气泡不会冲到液体的顶部并逸出。 它们将留在液体中。 这意味着与在地面上饮用苏打水相比,在太空中饮用苏打水的宇航员将吸入更多的气体。 喝碳酸饮料就像喝泡沫状的浆状。

That means there will be more of a need to burp, to release that gas.  That would be okay, except burping in space is unpleasant, for the same reason mentioned above for the soda.  On the ground, gases and liquids naturally separate in the digestive system because the lighter gases rise above the heavier denser liquids.  But, in micro-gravity, that doesn’t happen.  When one burps in space, it is often a “wet burp” which means some liquid is expelled.  It’s kind of like acid reflux.

这意味我们的宇航员将打更多的饱嗝,以释放出这种气体。 除了在太空中打嗝很不好玩之外,其他一切和地面上一样。 在地面上,气体和液体在消化系统中自然分离,因为较轻的气体上升到较重的稠密液体上方。 但是,在微重力下不会发生这种情况。 当在太空中打嗝,通常是“湿打嗝”,这意味着有一些液体被排出。 有点像反酸。

【评论区】

@ Dave Cunningham

Did they try using a non-carbonated soda with some added citric acid for tartness instead of carbonation? And would increasing the viscosity of the drink help in reducing “wet burps”? I am think of something on the order of almost “liquid ice cream” in consistency …

他们是否尝试使用过使用添加了柠檬酸的非碳酸苏打,来不是用碳酸? 增加饮料的粘度是否有助于减少“湿”? 我想到的几乎都是“液态冰淇淋”这样的东西。

答主答:

They did try adjusting the carbonation but came to the conclusion it defeated the purpose of drinking a Coke.

他们尝试过改变碳酸的含量,但最后发现那样就不叫可乐了。

@ Dave Cunningham

If they had kept the cocaine in it, the results might have been different 🙂

如果他们仍然把可卡因留在里面,结果可能就不同了:)

@ Gunnar Ahlberg

There’s a difference between coca leaf extract and cocaine…

古柯提取物和可卡因之间是有区别的…

@ Dave Cunningham

I fear you did not note the “:)” at the end of my comment. Snopes.com avers that Coke did contain some cocaine in it, but that by 1902 the amount of cocaine was 1/400 grain per ounce of syrup. A fellow MIT alum who was active in the 1970s in the New Jersey chemical company which produced the US syrup said that by then there was no detectable amount of cocaine in the product, and I trust him as well as Snopes.

我认为您在我的评论结尾没有注意到“ :)”。 Snopes.com认为可乐中确实含有一些可卡因,但到1902年,可卡因的量为每盎司糖浆1/400粒。 一位在1970年代活跃于生产美国糖浆的新泽西州化学公司的麻省理工学院的同班同学说,那时该产品中没有可检测到的可卡因含量,我相信他和Snopes一样。

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