在电影《阿波罗13号》的最后， Tom Hanks 触摸了指令服务舱的外壳，有没有可能让他的手烧伤？At the end of “Apollo 13” movie, when Tom Hanks touches the Odyssey bar in the sea, isn’t it supposed to burn his hands?
I assume you are referring to this moment, or the one later when he reached up from the rubber raft.
[Tom Hanks and Kevin Bacon, pretend astronauts leaving their pretend spacecraft.]
First, the Apollo capsule was coated with an ablative heat shield—meaning that as it passed through reentry heating, the heat shield slowly disintegrated, carrying the heat away as it shed material.
Second, the capsule emerged from the period of reentry heating at well above airliner cruising altitude, where the air is far below zero—and any residual reentry heat was quickly lost.
Third, once the spacecraft hit the water, it was doused in seawater, and so could not be hotter than about 212°F (100° Celsius), although it was already much cooler by then.
[The real splashdown of Apollo 13, as photographed through a recovery helicopter window.]
Fourth, even if the capsule had been dipped in flaming paraffin at the moment of splashdown, by the time the astronauts emerged, it had been bathed in the downdraft of a helicopter for several minutes while frogmen attached rubber flotation equipment and tested for propellant leaks—
—and opened the hatch…
—and opened the hatch…
So there was never any danger of anyone burning their hands.
如果宇航员降落在月球因为意外回不来了，有什么办法让他们安详地离开吗？Did the astronauts who landed on the Moon had the facilities to end their lives in the event that they couldn’t leave?
Yes. They had a spacesuit helmet seal and press/depress valves in both hatches.
In my story, “For All Mankind,” published in the July/August 2017 Analog Science Fiction & Fact, I have two astronauts who are sent out in Apollo hardware on a one-way mission that ends after they’ve been exposed to radiation. With the mission accomplished and one of them mortally ill and in pain, the healthier of the two suits up, closes the oxygen supply valves, and bleeds away enough air into space to allow her companion to pass out—but without permitting the cabin to drop all the way to vacuum. That done, she finished her log, tucks it away for future explorers to find, and pops the seal on her own helmet.
在我写的科幻故事《全人类》（2017年7月/ 8月《模拟科幻与事实》中发表）中，有两名宇航员在阿波罗计划被派往执行单向任务，直到他们暴露在辐射下才结束 。 完成任务后其中之一位生病了陷入痛苦之中，而稍微健康的一位则穿上宇航服，合上氧气供应阀，并向太空放出足够的空气以让其同伴昏迷，但不让机舱成为真空。 完成后，她整理了自己的日志，将其收集起来以备将来的探索者使用，然后将封条塞在自己的头盔上。
This would be quite a gentle way to go. You would simply pass out, then die in your unconscious sleep.
It’s often said that the Apollo astronauts would never have done this but, in fact, had they been marooned on the moon, they might have. After attempting all reasonable efforts at repair, and with no hope of rescue, they would reach a point where food, water, battery power, and oxygen were all becoming critical. If they took no action the first mortal threat would almost certainly be CO2 buildup, either because the scrubbers were saturated or because the batteries were no longer circulating the air. That would be a fairly unpleasant death, as you can sense CO2 elevation, and it would make you feel trapped and stifled, almost as if you were drowning.
人们常说，阿波罗宇航员永远不会这样做，但实际上，如果他们无法离开月球上，他们可能会这么做。 在尝试了所有合理的维修工作之后，并且没有任何挽救的希望，食物，水，电池电量和氧气都变得至关重要。 如果他们不采取任何行动，那么首要的致命威胁几乎肯定是二氧化碳的积累，这可能是因为过滤器已经饱和，或者是因为电池不再使空气流通。 那会是相当不愉快的死亡，因为您可以感觉到二氧化碳的升高，这会让您感到被困和窒息，几乎就像溺水一样。
Dropping the cabin pressure while you still had clean, warm, air and a full belly would be pretty peaceful and comfortable. You don’t need to feel the saliva boiling on your tongue or anything. Just drop the 100% oxygen left down to about .6 bar, sufficient to prevent boiling but not to support life, and it’s all over.
降低机舱压力 ，您会仍然保持干净，温暖，空气和饱满的肚子的情况下会非常安静和舒适。 您不会感觉唾液在舌头或其他任何东西沸腾。 只需将剩余的100％氧气降至约.6 bar，足以防止沸腾但无法继续维持生命，而且一切都结束了。
航天飞机退役后，为什么NASA并没有将航天飞机轨道留在ISS上，以便扩展了空间站的规模？Why didn’t NASA leave a shuttle orbiter attached to the ISS when the fleet was retired, thereby significantly expanding the station’s size?
Because, among other reasons, it would not have significantly expanded the station’s usable volume, but it would have significantly increased its mass—and therefore the amount of propellant needed to periodically boost it.
The shuttle’s crew cabin’s total pressurized volume was 74.3 cubic meters (2,625 cubic feet), while the ISS has a pressurized volume of 931.57 cubic meters (32,898 cu ft), so for the cost of a permanently occupied docking hatch, a shuttle would have increased usable space by a little under 8%. Granted, that includes a space galley, toilet, and living quarters, but much of the rest of the gear would be dead weight.
航天飞机的乘员舱的总加压体积为74.3立方米（2,625立方英尺），而国际空间站的加压体积为931.57立方米（32,898立方英尺），因此对于永久性停靠舱口的成本，航天飞机将增加 可用空间不到8％。 当然，其中包括一个太空厨房，卫生间和起居室，但是其余的大部分设备将都是没什么用的重量。
Speaking of weight, a shuttle orbiter has a dry mass of 171,000 pounds (77,564 kg) compared to the ISS at 919,965 pounds (417,289 kg).
So, the shuttle would have increased the ISS volume by 8% and its mass by nearly 20%. The shuttle main engines remain of not-inconsiderable value, and there are numerous parts of the shuttle interior that would become a maintenance burden after extended time in space—if not a danger to the crew, since the shuttle was never designed for continuous in-space servicing.
In the long run, the shuttle would have been a drain on ISS operations.
But as it is now, the shuttles are serving as repositories for spare parts for the ISS. Shortly before I visited Endeavor last spring in LA, NASA came by to harvest some expensive titanium storage tanks from it, for transport up to the station.
[I visited Endeavour with a Rockwell engineer who worked on some shuttle systems — and was a little star struck in its presence (hi Bill!)]
如果阿波罗11号无法离开月球，NASA有过营救计划吗？Did NASA have a rescue plan for Apollo 11 if they failed to leave the Moon?
They had a plan, just not a rescue plan.
Since rescue was impossible with the technology available at the time, President Nixon’s speech writer, William Safire, prepared this text, which the president would have delivered to the nation. The speech, dated July 18, 1969, two days before the landing, assumes they have crash landed or landed safely and been marooned by failure of the ascent engine. This was the worst-case scenario that planners worried about. Instead of Walter Cronkite coming on the news to report a crash or explosion, the whole world would have been able to watch and listen live as the crew said goodbye to their loved ones, then settled in to wait for their consumables to run out.
由于当时无法使用现有技术进行救援，因此尼克松总统的演讲撰稿人威廉·萨菲尔（William Safire）准备了这份案文，总统本来会交付给美国。 演讲于1969年7月18日，即着陆前两天，假定他们已经坠毁，或虽然安全着陆但由于上升引擎故障而被撞毁。 这是计划人员担心的最坏情况。 最后沃尔特·克朗凯特（Walter Cronkite）并没有在新闻中报道坠机或爆炸事件，而是当乘务员向亲人道别时，全世界都可以现场观看和聆听，然后安顿下来，等待其消耗品耗尽。
IN THE EVENT OF MOON DISASTER
Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace.
These brave men, Neil Armstrong and Edwin Aldrin, know that there is no hope for their recovery. But they also know that there is hope for mankind in their sacrifice.
These two men are laying down their lives in mankind’s most noble goal: the search for truth and understanding.
They will be mourned by their families and friends; they will be mourned by their nation; they will be mourned by the people of the world; they will be mourned by a Mother Earth that dared send two of her sons into the unknown.
In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood of man.
In ancient days, men looked at stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood.
Others will follow, and surely find their way home. Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts.
For every human being who looks up at the moon in the nights to come will know that there is some corner of another world that is forever mankind.
【博主补充：以下两张图是reddit的网友找到的，这件事在reddit引起了很多讨论 https://www.reddit.com/r/pics/comments/62c33k/the_speech_that_would_have_been_given_if_the_moon/ 。另外，我觉得知乎上这个问题的答案质量要比quora上这个高很多，传送门】
如何在实验室中测试火箭发动机而不让其自己飞走？ How are rocket engines tested in a laboratory without having the engine fly off on its own?
This might sound like a flippant answer but, “by bolting them in place.”
Ground tests are conducted by securing the engines and firing them up. This is sometimes done out in the open air and sometimes inside a giant vacuum chamber so arranged as to “soak up” the exhaust as it’s produced.
Engines are sometimes tested by themselves.
And sometimes in subassemblies:
And sometimes BIG assemblies:
Tests can be small:
Or tests can be large:
Large solid rocket boosters are often tested on their side:
And in at least one notable case, upside down: