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StrandedonEarth

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Posts posted by StrandedonEarth

  1. 1 hour ago, FusionNexus said:

    you might also notice its cheaper to adjust inclination mid transfer than from the orbit of another body (I believe its also cheaper to adjust inclination the further you are from the body your orbitting? not sure on this).

    The slower the orbital velocity, the less dV to change inclination, so yes, it’s cheaper in a higher orbit. In an elliptical “egg-shaped” orbit, ideally the An and Dn will be at the Pe and Ap. Since the orbit is slowest at the Ap, it takes less dV to change inclination there. 

  2. 10 minutes ago, sevenperforce said:

    Yes, but then you have no way to reboost Hubble, because the main thrusters are under the nosecone.

    Cosine losses on the aft translational thrusters would be prohibitive.

    Would it be possible to use the SuperDracos? I suppose they’d need to be modified from the current abort-use-only design. Would probably only need or want to fire two of them

  3. On 9/26/2022 at 11:32 PM, kerbiloid said:

    In the ancient and medieval legends, myths, and chronicles, when a person was changing his (every time the only) name, he was kinda reborn as another person, cancelling his previous life and beginning a new one.

    It stays incomprehensible for me, how several names at once can not result into split personality.

    (Not nicknames, but personal names).

    This also has roots in Numerology, where changing one’s name (number) apparently changes one’s personality. This even applies to nicknames. Ever notice that how you act changes when operating under a nickname (alter-ego, including online personas)? Spooky stuff, and totally non-scientific, but yet anecdotally noticeable. 
     

     

    On 9/27/2022 at 11:11 AM, TheSaint said:

    When I was a kid, my first name, my brother's first name, and our dog's name all started with the same first letter. So my dad would get them confused, especially when he was mad. He would yell out all three in sequence sometimes.

    My mom did that, and our names (including the dog’s) don’t even start with the same letter!

  4. 7 hours ago, kerbiloid said:

    So, the humans have just killed another innocent robot just to have fun by hitting a random stone far away.

    And accidentally destroyed the Dimorphos lunar base which was being built by the mini-civilisation of Didymos for centuries.

    A small consolation for them will be the bright ring of ejecta shining in sunlight (and also blocking their equatorial orbits for million years).
    Of course when they will be again able to watch the sky after getting from their underground vaults when the ejecta stop falling everywhere around.

    Nice.

    DART's last thought: "I wonder if it will be my friend?"

  5. 7 minutes ago, sevenperforce said:

    What will keep your back colder for longer: a pouch of water at 0°C, or a pouch of rubbing alcohol at -10°C? Assume that both pouches contain the same weight of coolant.

    You might think the rubbing alcohol would work better, because it's starting at a lower temperature. But you'd be wrong. The heat capacity of water is 74% higher than the heat capacity of rubbing alcohol, so by the time the alcohol temperature goes from -10°C to 35°C, the water will only have gone from 0°C to 25.8°C. That's because water is just better at absorbing heat than rubbing alcohol.

    Hmmm, but if the rubbing alcohol is not in a pouch, it will evaporate  more easily than the water, and carry away heat via evaporative cooling. So will water, but it evaporates more slowly. I don't know how the calculus works out in terms of heat capacities / heat of vaporization, etc, as to which is actually more effective per unit mass. On a side note, I've noticed spilling heptane on my nitrile gloves at work feels a lot colder than water, even though the water and heptane are at the same temperature, because of the rate of evaporation.

    11 minutes ago, sevenperforce said:

    You don't need more power; you need more delta-v.

    You need the same amount of delta-v. You need more thrust (which likely means heavier engines) to lift it, and more total impulse to impart the same delta-v to a heavier mass, which requires more propellants, and then the "tyranny of the rocket equation" rears its ugly head....

  6. 37 minutes ago, Spacescifi said:

    Brittle? As in easy to break?

    Brittle, as in breaks instead of flexes. When the Ship flexes, vibrates, or otherwise changes shape ever-so-slightly, the tungsten will chip, shatter, or otherwise flake off.

    Early plans for Starship skipped tiles for a “sweating methane” solution, but I guess the math or sims didn’t work out…

    More layers of anything adds mass. Mass in spaceflight is bad. 

  7. 21 hours ago, HvP said:

    Over and over again we see that when drivers believe it is safe to drive fast the roads actually become less safe.

    I've heard that the biggest danger is cars moving at different speeds on the same road. Lane changes become quite dangerous when traffic is coming up the other lane 30+kph faster (speaking from experience...)

  8. 36 minutes ago, SunlitZelkova said:

    Is it known what Musk’s ICBM based Mars architecture was supposed to look like?

    Or was this merely an idea in his head that never got beyond the words “use retired ICBMs to get to Mars” before he found out he couldn’t buy them and decided to do SpaceX?

    I believe the plan was to land little greenhouses to experiment with growing things on Mars. Humans on Mars were not part of that plan. 

    I think it was discussed in the book about the history of SpaceX, “Liftoff…” by Eric Berger, but I could be wrong about that. 

  9. 2 hours ago, Codraroll said:

    It can get to a point where the discrepancies between the movie and reality become very distracting, though. Usually when the writers fall back on "... and then this happens!" as a major plot point or set piece, and the audience goes "Umm, that wouldn't happen at all".

    I think the worst example I've seen in a blockbuster movie was that G.I. Joe movie where a seafloor base underneath the Arctic ice cap is destroyed by blowing up the ice sheet above it. Huge chunks of ice then sink down at freefall speeds and crush the base. Some visual effects director must have had this great vision he pushed through, unaware of the fact that ice floats in water. Hence why it forms on the surface to begin with, and not on the seafloor.

    Yeah, some of the procedural dramas my wife and I watch fall into the category of “but they wouldn’t do it that way!” I’m not even in that industry and I know that if they tried to do it that way they’d get fired if they didn’t get killed. 

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