Robert Frost 在quora上有关航天的回答收集(二)

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

Has there ever been a collision between two satellites orbiting Earth?在环绕地球运行的两颗卫星之间是否曾发生过碰撞?

Yes. In 2009, a 900 kg failed Russian satellite collided with one of Iridium’s communications satellites, destroying them both and creating hundreds of pieces of dangerous debris that now must be tracked. That was an accident, but shows the importance of designing safe retirement into satellites.

是。 2009年,一枚900公斤失灵的俄罗斯卫星与铱星计划的一颗通信卫星相撞,将其摧毁,并制造了数百片危险碎片,现在必须对其进行追踪。 那是一次意外,但显示了将安全退役设计对卫星的重要性。

Another incident didn’t involve two satellites colliding, but did involve the collision of a satellite and a Chinese missile, followed by satellite debris hitting another satellite. It was sheer stupidity. In 2007, the Chinese government deliberately destroyed a satellite with a missile, just to show they could. That destruction strewed thousands of pieces of debris into a cloud ranging from an altitude of 200 km to 3850 km – effectively all of LEO. About 1000 pieces of the debris are greater than 10 cm – making them quite deadly. In 2013, a Russian satellite was hit by a piece of that debris.

另一个事件不涉及两个卫星的碰撞,但涉及一枚卫星和一枚中国导弹的碰撞,随后又有卫星碎片撞击另一颗卫星。 那真是愚蠢。 2007年,中国政府用导弹摧毁了一颗卫星用于实验。 这次破坏将数千块碎片撒入了从200 km到3850 km高度不等的云中-,实际上是所有LEO。 大约1000块碎片大于10厘米-使其非常致命。 2013年,一枚俄罗斯碎片击中了一枚俄罗斯卫星。

【补充:太空垃圾数量,以及知乎上的回答

知乎用户@ Devymex Wang 的评论

2007年中国反卫星导弹试验是指中国于2007年1月11日进行的一次反卫星导弹试验。在该试验中,由西昌卫星发射中心 (28°14′49″N 102°01′30″E / 28.247°N 102.025°E)发射的一枚开拓者一号火箭携带动能弹头,以反方向8公里/秒的速度[1],击毁了轨道高度865公里,重750公斤的该国已报废的气象卫星风云一号C[2],是自1985年美国发射ASM-135反卫星导弹摧毁P78-1人造卫星以来首次成功的人造卫星拦截试验。[3]
美国《航空和空间技术周刊》最早报道了该事件,该报道内容于2007年1月18日被美国国家安全委员会的发言人所证实。[4] 中国政府最初并未公开表态,直至外交部2007年1月23日正式承认了该试验。[5] 中国在事前已经就该试验通知包括美国和日本在内的其他国家。[6]

【总的来说,太空垃圾的主要来源是反卫星导弹干掉卫星后产生的垃圾。中国在2007年的一次反卫星实验直接让太空垃圾数量飙升了3000左右】

国际空间站在2024年关闭后会怎么样?被留在太空吗?How will the ISS shut down in 2024? Will it be left in space?

When ISS has reached the end of its operational lifetime (whether that be in 2024 or later), it will be disposed of in the same way the Russian space station Mir was disposed of – the vehicle will maneuver so that whatever cargo vehicle is docked can fire its thrusters in a retrograde burn.  That burn will decelerate the vehicle so that it will drop to a lower orbit.  The thicker atmosphere in conjunction with whatever additional burns the cargo vehicle can provide will force the vehicle to deorbit.  It will largely burn up and come apart in the upper atmosphere.  Some components (such as my beloved control moment gyroscopes) will survive the descent, but the deorbit will be timed so that the debris rains down over the Pacific ocean.

当国际空间站达到使用寿命(无论是在2024年或更晚)时,其处置方式将与处置俄罗斯和平号空间站的方式相同——空间站将进行机动,以便与其对接的任何货运载具都可以启动引擎并远离空间站。 燃料燃烧将使载具减速,使其下降到较低的轨道。 较浓的大气加上货运载具可能提供的任何额外燃烧,将迫使载具离开轨道。 它会大量燃烧并在高层大气中分解。 某些组件(例如我钟爱的控制力矩陀螺仪)将在下降后幸存下来,但脱离轨道的时间会计算好,以便碎片落下太平洋。

My colleagues and I, like Captain Kirk, Dr. McCoy, and the rest of the crew, will watch as our baby and the focus of our career turns to ash.

我的同事和我,像柯克上尉,麦考伊博士以及其他工作人员一样,将注视着我们的孩子,而我们的职业重心变成了灰烬。

地球上的金是从哪儿来的?从别的星星上来的吗?还是在地球上形成的?Where did the gold on Earth come from? Did it come from stars? Why would gold not have formed on Earth itself?

It takes a massive amount of energy to make elements.  The Earth does not have enough energy.  Jupiter does not have enough energy.  In fact, Jupiter would need to be 75 times larger to have enough energy for fusion to begin.

生成元素需要大量能量。地球没有足够的能量。木星也没有足够的能力。实际上,木星需要大75倍才能拥有足够的能量来开始聚变。

The lightest elements (hydrogen, helium, lithium) were formed in the big bang.

大爆炸中形成了最轻的元素(氢,氦,锂)。

A young healthy star ‘burns’ hydrogen.  The hydrogen is fused into helium.  As the star ages it can become a red giant.  At this point the helium can ‘burn’ into carbon, carbon can ‘burn’ into neon, neon can ‘burn” into oxygen, oxygen can ‘burn’ into silicon, and silicon can ‘burn’ into iron.

一颗年轻健康的恒星“燃烧”氢气。氢熔化成氦。随着恒星的老化,它可能会变成红色巨人。此时,氦气可以“燃烧”为碳,碳可以“燃烧”为氖,氖可以“燃烧”为氧气,氧气可以“燃烧”为硅,而硅可以“燃烧”为铁。

Iron is very stable.  It doesn’t release energy, so the star’s element factory ends with iron.

铁非常稳定。它不会释放能量,因此恒星的元素工厂以铁结尾。

More elements can be produced in a supernova.  Supernova nucleosynthesis can make silicon, sulfur, chlorine, argon, sodium, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, and nickel. and then neutron capture processes (R-process and S-process) can produce some of the elements heavier than nickel.

超新星可以产生更多的元素。超新星的核合成可以制造硅,硫,氯,氩,钠,钾,钙,scan,钛,钒,铬,锰,铁,钴和镍。然后中子俘获过程(R过程和S过程)会产生一些比镍重的元素。

It was assumed that gold was also made in a supernova, but recent observations indicate that the heaviest atoms, including gold, are formed during the collision of two neutron stars.

以前认为金也是在超新星中制造的,但是最近的观察表明,包括金在内的最重的原子是在两个中子星碰撞时形成的。

宇宙中最热的物体是什么?What is the hottest object in the universe?

On a typical day, one contender is the white dwarf that is at the heart of the Red Spider Nebula (NGC 6537).  The surface temperature of that star is around 300,000 K (540,000 R).  That’s 50 times hotter than our sun.

通常情况下,这最由可能是位于红蜘蛛星云(NGC 6537)核心的白矮星。 那颗恒星的表面温度约为300,000 K(540,000 R)。 那比我们的太阳高50倍。

Or you could go with a quasar, where the center burns 100 times as much energy as the Milky Way.  The gas around a quasar can reach a temperature of 80 million degrees.

或者,类星体的温度也很高,该类星体的中心能量消耗是银河系的100倍。 类星体周围的气体可以达到8000万度的温度。

But if you were visiting CERN in July of 2012, you would have been present to see, briefly, the production of a quark-gluon plasma that had a temperature of about 5.5 trillion degrees Kelvin.

但是,如果您在2012年7月访问欧洲核子研究组织(CERN),您可能会短暂地看到夸克-胶子等离子体的产生,其温度约为开尔文5.5万亿度。

And if you’d been present at the Big Bang, you would have observed the Planck temperature 1.416E32 Kelvin.

而且,如果您曾经在“宇宙大爆炸”的现场,您将观察到普朗克温度为1.416E32开尔文。

Personally, I would say the answer is Monica Bellucci, at a temperature of Absolute Hot.

但就我个人来说,我认为答案是  Monica Bellucci ,她非常非常热辣。

你如何向一个小孩子解释黑洞?How can you explain black holes to a kid?

  • Take a large piece of plastic food wrap (Saran Wrap) and hold it. 
  • Put a small ball in the middle so that the sheet dips. 
  • Pour a couple of drops of water on the sheet. They should roll down the wrap towards the ball. This illustrates gravity.
  • Remove the ball and have the child use his/her finger to push down and bend the sheet. They will see that the harder they push (heavier the object) the more the plastic wrap bends.
  • Have them push their finger hard enough to make a hole in the wrap.  That would be an extremely heavy object.
  • Pour a couple of drops of water on the sheet. They should flow down and through the hole.
  • Explain that a black hole is an object so heavy that it bends space so much that anything that falls in can’t ever come back (like the water that fell through the hole).
  • 取一个大的塑料食品保鲜膜。
  • 在中间放一个小球,使保鲜膜弯曲。
  • 将几滴水倒在保鲜膜上。 它们应该将朝球方向滚动。 这说明了重力。
  • 移开球,让孩子用他/她的手指向下推动并弯曲保鲜膜。 他们将看到,推力越重(物体越重),保鲜膜的弯曲度就越大。
  • 让他们用力推动手指以在包装上打一个洞。 那将很困难。
  • 将几滴水倒在板上。 它们应向下流动并通过孔。
  • 说明黑洞是一个引力非常大的物体,它弯曲的空间太大,以至于任何落入的物体都不可能回来(例如从该洞落下的水)。

@ Oliver Emberton

Impressive. Now can you explain “co-operation” to Congress? It’s a bit more difficult, I’ll admit…

令人印象深刻!现在你如何向国会解释“合作”呢?我觉得这要困难多了…

答主:

That is way beyond me!

这也是我所面临的问题!

@ Tony Waters

How to explain Congress to a 4 year old:

如何向四岁小孩解释国会

  • Explain that a Congress is an object so heavy that it bends space so much that anything that falls in can’t ever come back (like the money that fell through the hole).
  • 国会是非常重的物体,引力也非常大,它弯曲了空间,所有掉进他们那儿的东西都再也回不来了(就像掉进洞里的钱一样)

@ Alon Amit

I’ve always loved that metaphor, but of course: Teaching Physics

我喜欢这个比喻,但我也喜欢这个 https://xkcd.com/895/

【xkcd是个神奇的网站,干脆把图放上来吧】

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