# Tag Info

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I think Sagan was being optimistic. The original plan was for a large fleet of shuttles to support a very high mission flight rate, but according to Wikipedia, by 1983, the plan was to hold the fleet at four orbiters (not counting Enterprise, which was not spaceworthy): On January 5, 1979, NASA commissioned a second orbiter. Later that month, Rockwell began ...

8

Source (cropped) Why do plastic rulers make you measure between two lines, instead of starting at the edge? tl;dr: Never use the edge of a ruler or the "zero" of any analog measuring device when you are making careful measurements if you can help it. Instead try measuring between two equivalent demarkations. from this answer; doesn't start moving ...

5

Here is one russian speaking source that discusses this issue. I have run it through Google Translate for you, but can't guarantee the translation quality. The quoted text is rather lengthy. Several key paragraphs at the start have been manually checked and updated. The title is paraphrasing the slang expression "down the drain", which in Russian, literally ...

5

I don't know the exact details of the Gemini suit, but here are some contemporaneous patents that describe similar joints. The different parts are in red and blue, bearings in green and o-rings yellow. Omni-directional high altitude helmet, US3030626A by Leonard F Shepard, filed 1958: It's basically a large ball bearing with an o-ring, both in such an ...

4

Converting between different frames of reference is pretty straight forward. You subtract the velocities. That's it. If you have the spacecraft's velocity relative to the Earth, you can just subtract the Moon's velocity relative to Earth. Then you have the spacecraft's velocity relative to the Moon. In the case of a lunar transfer orbit, the spacecraft is ...

3

When designing a rocket engine you need to design the turbo pumps for the propellants and the combustion chamber. To design a turbopump you need to know its output pressure and the volume flow rate. To determine the output pressure you need to know the chamber pressure. To design the walls of the combustion chamber you need to know the chamber pressure to ...

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