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
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
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.
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.
Re-did my math. You need to lose 5.43m/s. Think I forgot to include the Earth’s radius at some point.
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 5.43m/s, it would need to eject its entire pressurized atmosphere at a velocity of 2389m/s or 5344mph.
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.
Doesn’t need to be forward and up, just forward, orbital physics is fun that way. And yeah, even if all ~1200 kg of air in the ISS’s pressurized volume escaped at the speed of sound (completely unrealistic overestimate), the station’s velocity change would be around 1 m/s, which is only enough to decrease its orbit by a kilometer or two.
Fake: FEMA? Seriously?
Gay: anon is constantly thinking about cracks
Why would the consequence of a structural crack be the cause of a de-orbit and not an explosive depressurization anyway?
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.
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
Yup, but boosting and turning would both be things you wouldn’t want to do with a weakened frame.
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.
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.Re-did my math. You need to lose 5.43m/s. Think I forgot to include the Earth’s radius at some point.
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 5.43m/s, it would need to eject its entire pressurized atmosphere at a velocity of 2389m/s or 5344mph.
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.
there should be awards for doing math on the internetz, here’s the best I can do 🏆
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.
Doesn’t need to be forward and up, just forward, orbital physics is fun that way. And yeah, even if all ~1200 kg of air in the ISS’s pressurized volume escaped at the speed of sound (completely unrealistic overestimate), the station’s velocity change would be around 1 m/s, which is only enough to decrease its orbit by a kilometer or two.