• rbesfe@lemmy.ca
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    4 months ago

    Everyone likes to joke about this manhole cover flying around in space, but if you do the math on the aerodynamic heating you get a temperature higher than the boiling point of iron.

    • PeriodicallyPedantic@lemmy.ca
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      4 months ago

      But also at that speed it’d only be in the atmosphere for a couple seconds; even at that high temp it may not have been able to transfer all that energy into the manhole cover. The energy may have just gone into ablating away the surface.

      But it probably ablated away the whole mass of the manhole cover.

    • phdepressed@sh.itjust.works
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      4 months ago

      What is irons vaporization temp? And wouldn’t space cool it down(and keep it somewhat together barring other gravitational objects affecting it.

      • The Stoned Hacker@lemmy.world
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        4 months ago

        space might not cool it down because the only real way for it to lose the heat would be blackbody radiation. by now it’s probably cooled off but without any atmosphere or other materials to cool it off, it probably stayed hot for a while

      • ColeSloth@discuss.tchncs.de
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        4 months ago

        Iron goes molten at 2,800f. The air friction would have caused that long before getting to space. As for staying together and resolidifying in space…well imagine how well maple syrup would stay held together if you threw it out of a cup pretty hard. The iron would have went molten and just proceeded to “spatter” and not have any piece left heavy enough to keep up an escape velocity.

  • themeatbridge@lemmy.world
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    4 months ago

    I love the juxtaposition of these:

    During the Pascal-B nuclear test of August 1957, a 900-kilogram (2,000 lb) iron lid was welded over the borehole to contain the nuclear blast, despite Brownlee predicting that it would not work.

    A high-speed camera, which took one frame per millisecond, was focused on the borehole because studying the velocity of the plate was deemed scientifically interesting.

    This idea is so incredibly stupid that science needs to study precisely how much it won’t work.

    Like, I wonder if the person who insisted on welding the lid in place had to go to a debriefing meeting where Brownlee showed the frame-by-frame of the lid. “So here we see the lid, and- Oh, it’s gone! Look at that. Gary, did you see it? The lid you put on there to cOnTaIn ThE bLaSt, you can see it for one thousandth of a second, and then it’s gone. It’s either in outerspace or it has been vaporized, and we’re never going to know because it happened so fast. So fast, Gary. A for effort, though. It was definitely worth bringing in the crane and a whole welding crew. Time and money well spent, because we now have a better understanding of the magnitude of how stupid you are, Gary. Here’s a print of that one millisecond for you to hang in your office. Get fucked, Gary.”

    • IDew@lemm.ee
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      4 months ago

      When Pascal-B was detonated, the blast went straight up the test shaft, launching the cap into the atmosphere at a speed of more than 66 km/s (41 mi/s; 240,000 km/h; 150,000 mph).

      Woaw. Just wow.

      Very interesting article, thanks for quoting it lol

      • EddoWagt@feddit.nl
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        4 months ago

        For reference, earths escape velocity at the surface is about 11 km/s. I’m not sure how quickly the cap would slow down, but if it hadn’t been vaporised it surely would be orbiting the sun right now.

        Also, the escape velocity from the Sun at Earths distance would be 16.6 km/s on top of earths speed, so depending on the direction it could’ve escaped the suns orbit as well.

        But it was most likely vaporised