Comment on Anon has a warning about the ISS

NOT_RICK@lemmy.world ⁨1⁩ ⁨week⁩ ago

• DaddleDew@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Why would a crack cause it to de-orbit to begin with?

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  • NaibofTabr@infosec.pub ⁨1⁩ ⁨week⁩ ago

    A structural crack wouldn’t necessarily be in the hull of the habitat modules. The ISS has a big frame (the Integrated Truss Structure) which supports the solar arrays, power distribution and heat radiators. If the frame is damaged, firing the engines to maintain orbit might be impossible.

    Atmospheric drag reduces the altitude by about 2 km a month on average. Orbital boosting can be performed by the station’s two main engines on the Zvezda service module

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    • Tar_alcaran@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

      And most supply missions give it a boost before leaving as well. Also, the ISS can “glide” by turning it’s narrow end forward, getting less drag from the atmosphere and reduce the decay rate at the cost of power generation

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      • NaibofTabr@infosec.pub ⁨1⁩ ⁨week⁩ ago

        Yup, but boosting and turning would both be things you wouldn’t want to do with a weakened frame.

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      • corsicanguppy@lemmy.ca ⁨1⁩ ⁨week⁩ ago

        it’s narrow end

        is it?

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  • Evil_incarnate@lemm.ee ⁨1⁩ ⁨week⁩ ago

    I hope it’s all bullshit but if it’s a tiny crack, but facing forward and up, the escaping air would push it down. I can’t math it but I guess it would only be a small effect.

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    • ryedaft@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

      It’s almost two months old. People would probably have noticed by now if the sky was falling. Like, you can look at ISS from Earth.

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    • ch00f@lemmy.world ⁨1⁩ ⁨week⁩ ago

      It wouldn’t have to face up, it would have to face retrograde from the ISS orbit to bleed off velocity and allow it to fall. According to my interpretation of Wikipedia’s description of the Hohmann transfer which is the most efficient way to change orbits, you need -2081m/s change to drop from 420km to 415km. We can ignore the circularizing burn which would only be like 5m/s.

      Calculating gas exit velocity through a hole is tricky, but we can do it by momentum shift. The entire 1000m^3 pressurized volume of 1atm air at a cozy 70F has a mass of around 1000kg. If we assume 1000kg is small compared to 440,000kg of the entire space station, we can do a simple m1v1 = m2v2 equation.

      For the 440,000kg station to decelerate by 2081m/s, it would need to eject its entire pressurized atmosphere at a velocity of 915km/s or 2,048,000mph or 0.3% the speed of light.

      So yeah, I don’t think a pressure leak is enough to do it.

      Not to mention that the ISS already loses 2km/month due to drag in the thin atmosphere.

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      • barkingspiders@infosec.pub ⁨1⁩ ⁨week⁩ ago

        there should be awards for doing math on the internetz, here’s the best I can do 🏆

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