• Quereller@lemmy.one
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    1 year ago

    Fun fact, everything with a high velocity (and a certain mass) has a lot of kinetic energy.

    (Now think of space ships going light speed. You don’t need photon torpedoes)

    • Cethin@lemmy.zip
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      1 year ago

      True, but to hit things within the atmosphere it needs high mass and low drag. The ISS re-entering would have high mass but high drag, and most of it would fall apart when entering and be slowed down by drag so the energy gets spread through a long streak on the atmosphere instead of on the target

      • skillissuer@discuss.tchncs.deM
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        1 year ago

        i’m not sure that drag even matters that hard, you need big sectoral density and a way to prevent tumbling

        https://en.wikipedia.org/wiki/Impact_depth

        Meteorite: As may be concluded from the air pressure, the atmosphere’s material is equivalent to about 10 m of water. Since ice has about the same density as water, an ice cube from space travelling at 15 km/s or so must have a length of 10 m to reach the surface of the earth at high speed. A smaller ice cube will be slowed to terminal velocity. A larger ice cube may also be slowed, however, as long as it comes in at a very low angle and thus has to pierce through a lot of atmosphere. An iron meteorite with a length of 1.3 m would punch through the atmosphere; a smaller one would be slowed by the air and fall at terminal velocity to the ground.

        talking about tungsten we’re looking at minimum 50cm long darts, however this ignores atmospheric erosion

      • lightnsfw@reddthat.com
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        1 year ago

        If it was going fast enough wouldn’t it just blow through that before it had a chance to fall apart too much?

        • Cethin@lemmy.zip
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          1 year ago

          It depends on the angle really. I would expect it to be dropped from low earth orbit so, unless it’s given some strong retrograde push (also removing most of its energy from orbital velocity), the angle it’d be coming in at would be pretty shallow, so it’d have to go through a lot of atmosphere, so drag is very important.