4 ms·

starting to see symptoms of something that could lead to Kessler Syndrome

by solarpunk 2y ago

Dylan16807 2y ago
At that altitude? I don't know. This debris should clear out in a few years, right?
- dotancohen 2y ago
  Maybe twenty years, after taking out the Starlink constellation and most other satellites below ~400 KM. I'm sure that we'd still risk unmanned launches to higher altitudes during this time, but manned launches would very likely be restricted, at least by risk-adverse NASA.
  - WJW 2y ago
    A starlink satellite has a life expectancy of only about 5 years anyway, and that is WITH station keeping ion thrusters. Anything smaller than a starlink satellite will likely have an even shorter lifespan due to having worse mass vs surface area ratio because of the square cube law, and should be gone within a few years. Anything larger can easily be tracked with radars etc and should still be gone relatively quickly.
    - dotancohen 2y ago
      Yes, but we won't have use of the functionality that the Starlink satellites provide for the duration of the natural deorbits from ~400 KM.
  - treyd 2y ago
    Smaller debris deorbits faster, Starlink is in VLEO.
    - dotancohen 2y ago
      Yes, but the ISS debris would be raining down on it from about ~400 KM - so it will take a bit longer for all that to come down.
      - Dylan16807 2y ago
        There would need to be a lot of it to overcome continued launches. Once each piece of debris is coming down to that altitude it doesn't have a lot of time left.
- mihaaly 2y ago
  Yes. "At around 400 kilometers and into the 500-km realm — home to ISS and the SpaceX Starlink satellites among others — atmospheric drag plays a major role. Dead satellites and debris usually slow and burn up in the atmosphere in just a few years. This natural cleansing process accelerates when the sun becomes more active and solar coronal mass ejections strike Earth and cause the atmosphere to swell." https://aerospaceamerica.aiaa.org/features/understanding-the-misunderstood-kessler-syndrome/ https://aerospaceamerica.aiaa.org/features/understanding-the... Still, if the events occur not once in a decade but multiple times a year that could mean trouble for space travel: "Linares sees a potential future where 'humans probably don’t have any incentive to launch satellites, because we’re losing 50% of them' to collisions with debris, he says."
- bagels 2y ago
  At 350km a lot will live less than a year
WJW 2y ago
How can you possibly tell that from something that happens regularly anyway?
- belter 2y ago
  "One bacterium is put in a bottle at 11:00 a.m. and it is observed that the bottle is full of bacteria at 12:00 noon. Here is a simple example of exponential growth in a finite environment. This is mathematically identical to the case of the exponentially growing consumption of our finite resources of fossil fuels. 11:58 a.m. -> Bottle is one quarter full. 11:59 a.m. -> Bottle half-full ! 12:00 noon -> Bottle is full ! https://www.albartlett.org/articles/art_forgotten_fundamentals_part_4.html#:~:text=One%20bacterium%20is%20put%20in,finite%20resources%20of%20fossil%20fuels https://www.albartlett.org/articles/art_forgotten_fundamenta....
  - WJW 2y ago
    This does not answer my question, unless you also have proof that the amount of cases of the ISS crew having to take shelter is also increasing exponentially. Since the astronauts went back to work after 1 hour instead of moving back to Earth, we can infer that the perceived danger has passed. (That is quite beside the point that Kessler syndrome at that altitude is definitely not the type of "exponential growth in a finite environment" that the linked article describes, because orbital decay means that the smaller the particles get, the faster they will deorbit themselves)
  - tedunangst 2y ago
    And at 12:01 there's two bottles of bacteria!
  - feoren 2y ago
    That shows such a poor understanding of exponential growth that it makes me think this person should not be teaching physics. First of all, exponential growth basically doesn't ever actually occur in nature: everything has a carrying capacity. Sometimes the carrying capacity is so high it doesn't matter, but clearly in the case of the bottle it does. The growth will slow down significantly as the bacteria approaches the capacity of the bottle. The bottle could easily be half full as early as 11:30 as the available food for the bacteria starts becoming scarce enough to limit its growth. Secondly, 2^60 bacteria would weigh about 1,100 kg. Assuming the bottle is 1L (larger than a standard wine bottle), you'd need over 1000 bottles to house that much bacteria. So no, if it doubles every minute, then the bottle has been full for the last 10 minutes. I'm being generous and assuming some process is keeping the flask continuously well-mixed, otherwise you don't even have exponential growth in the ideal case (it's limited by the expanding surface area of the colony). You might think I'm being pedantic, but the entire exercise is to put some "real world" context to blow the minds of people and illustrate how exponential growth "really" works. But that's not how exponential growth really works in the real world, at all. Instead it's just taking a model of spherical cows to an absurd conclusion that only serves to further confuse people's understanding of the world. It's like those awful anti-intuition-pumps (intuition sinks?) about stretching all your DNA from end-to-end.

starting to see symptoms of something that could lead to Kessler Syndrome

Dylan16807 2y ago

At that altitude? I don't know. This debris should clear out in a few years, right?

dotancohen 2y ago
Maybe twenty years, after taking out the Starlink constellation and most other satellites below ~400 KM. I'm sure that we'd still risk unmanned launches to higher altitudes during this time, but manned launches would very likely be restricted, at least by risk-adverse NASA.
- WJW 2y ago
  A starlink satellite has a life expectancy of only about 5 years anyway, and that is WITH station keeping ion thrusters. Anything smaller than a starlink satellite will likely have an even shorter lifespan due to having worse mass vs surface area ratio because of the square cube law, and should be gone within a few years. Anything larger can easily be tracked with radars etc and should still be gone relatively quickly.
  - dotancohen 2y ago
    Yes, but we won't have use of the functionality that the Starlink satellites provide for the duration of the natural deorbits from ~400 KM.
- treyd 2y ago
  Smaller debris deorbits faster, Starlink is in VLEO.
  - dotancohen 2y ago
    Yes, but the ISS debris would be raining down on it from about ~400 KM - so it will take a bit longer for all that to come down.
    - Dylan16807 2y ago
      There would need to be a lot of it to overcome continued launches. Once each piece of debris is coming down to that altitude it doesn't have a lot of time left.
mihaaly 2y ago
Yes. "At around 400 kilometers and into the 500-km realm — home to ISS and the SpaceX Starlink satellites among others — atmospheric drag plays a major role. Dead satellites and debris usually slow and burn up in the atmosphere in just a few years. This natural cleansing process accelerates when the sun becomes more active and solar coronal mass ejections strike Earth and cause the atmosphere to swell." https://aerospaceamerica.aiaa.org/features/understanding-the-misunderstood-kessler-syndrome/ https://aerospaceamerica.aiaa.org/features/understanding-the... Still, if the events occur not once in a decade but multiple times a year that could mean trouble for space travel: "Linares sees a potential future where 'humans probably don’t have any incentive to launch satellites, because we’re losing 50% of them' to collisions with debris, he says."
bagels 2y ago
At 350km a lot will live less than a year

WJW 2y ago

How can you possibly tell that from something that happens regularly anyway?

belter 2y ago
"One bacterium is put in a bottle at 11:00 a.m. and it is observed that the bottle is full of bacteria at 12:00 noon. Here is a simple example of exponential growth in a finite environment. This is mathematically identical to the case of the exponentially growing consumption of our finite resources of fossil fuels. 11:58 a.m. -> Bottle is one quarter full. 11:59 a.m. -> Bottle half-full ! 12:00 noon -> Bottle is full ! https://www.albartlett.org/articles/art_forgotten_fundamentals_part_4.html#:~:text=One%20bacterium%20is%20put%20in,finite%20resources%20of%20fossil%20fuels https://www.albartlett.org/articles/art_forgotten_fundamenta....
- WJW 2y ago
  This does not answer my question, unless you also have proof that the amount of cases of the ISS crew having to take shelter is also increasing exponentially. Since the astronauts went back to work after 1 hour instead of moving back to Earth, we can infer that the perceived danger has passed. (That is quite beside the point that Kessler syndrome at that altitude is definitely not the type of "exponential growth in a finite environment" that the linked article describes, because orbital decay means that the smaller the particles get, the faster they will deorbit themselves)
- tedunangst 2y ago
  And at 12:01 there's two bottles of bacteria!
- feoren 2y ago
  That shows such a poor understanding of exponential growth that it makes me think this person should not be teaching physics. First of all, exponential growth basically doesn't ever actually occur in nature: everything has a carrying capacity. Sometimes the carrying capacity is so high it doesn't matter, but clearly in the case of the bottle it does. The growth will slow down significantly as the bacteria approaches the capacity of the bottle. The bottle could easily be half full as early as 11:30 as the available food for the bacteria starts becoming scarce enough to limit its growth. Secondly, 2^60 bacteria would weigh about 1,100 kg. Assuming the bottle is 1L (larger than a standard wine bottle), you'd need over 1000 bottles to house that much bacteria. So no, if it doubles every minute, then the bottle has been full for the last 10 minutes. I'm being generous and assuming some process is keeping the flask continuously well-mixed, otherwise you don't even have exponential growth in the ideal case (it's limited by the expanding surface area of the colony). You might think I'm being pedantic, but the entire exercise is to put some "real world" context to blow the minds of people and illustrate how exponential growth "really" works. But that's not how exponential growth really works in the real world, at all. Instead it's just taking a model of spherical cows to an absurd conclusion that only serves to further confuse people's understanding of the world. It's like those awful anti-intuition-pumps (intuition sinks?) about stretching all your DNA from end-to-end.