5 ms·

> Debris don't really accumulate dangerously in this zone and collision avoidance is a well-studied problem with a lot of people doing great work. I think this

> Debris don't really accumulate dangerously in this zone and collision avoidance is a well-studied problem with a lot of people doing great work. I think this line of thinking is dangerously incorrect. Sure it’s not a problem right now but we’re poised to have a lot more stuff in orbit than we’ve ever had before. Plastic waste didn’t initially “accumulate dangerously” either but once it became more widely used (and did accumulate dangerously) it was much more difficult to try to reign it back.

hinkley 4y ago
In this case it's policy reflecting Little's Law: population = arrival rate X duration of visit If suddenly someone wants to launch twice as many satellites, you either have to reduce tenancy or accept a higher population in the system. If you have a policy that's at most 25 years and a lot of satellites de-orbit in say 15 years on average, you can still triple your launches by pulling that down to 5. I am worried though, do we really build satellites that are expected to only work for 5 years? Are we disincentivizing people from building 20 year satellites this way?
- Fatnino 4y ago
  I assume it means deorbit within 5 years after the satellite is decommissioned.
- ntrz 4y ago
  The article says "5 years after completing their mission", not 5 years after launch.
  - hahajk 4y ago
    time to assign 25 year missions to satellites built to last 10 years!
    - simonh 4y ago
      Every mission has to pass FCC approval, and we're just discussing a super high level gloss of the rules. Thee's no way that would pass, so that's really not an issue.
  - hinkley 4y ago
    Wait, really? What orbital mechanics take five years to achieve? Lunar assisted orbital insertion burns only take a year or two, right? Why wouldn’t the deorbit burn start the day after decommissioning?
    - zardo 4y ago
      If it takes 5 years, there is no deorbit burn.
bryanlarsen 4y ago
Debris does not accumulate in LEO, it reenters naturally. This isn't like plastic waste, it's more like organic waste that naturally decays. Sometimes the law says you have to clean up organic waste, but sometimes it's better to let it rot on its own.
- mikeyouse 4y ago
  The timeframe varies widely based on the shape of the object and the altitude. There are something like 5 orders of magnitude pressure difference between an object at 100km and one at 500km which is the difference between deorbiting in days vs years.
  - bryanlarsen 4y ago
    There's probably more than 5 orders of magnitude difference between throwing an apple core into the woods and a city's worth of sewage, but both are organic waste. I think the analogy is fairly sound.
    - haimez 4y ago
      While true, there’s also an asymmetry here in that a city can expand their landfill or sewer system capacity- orbital space has a fixed capacity
      - bryanlarsen 4y ago
        WTF? Space is incomprehendibly big. The number of potential landfill locations are very limited.
        saghm 4y ago
        Isn't this thread discussing a very specific orbital range? The 450k-800k range is big, but I'm not sure I'd classify it as "incomprehensibly big".
MichaelCollins 4y ago
https://www.youtube.com/watch?v=mQT5aMa_7iI https://www.youtube.com/watch?v=mQT5aMa_7iI "Gabbard Diagram for Low Earth Orbit 1959-2021" See how the stuff in the lower left corner speeds up towards the lower left corner? That's low flying debris falling out of space.
- wpietri 4y ago
  I am generally allergic to video, but that was fascinating to watch. Thanks for sharing it.
- ericbarrett 4y ago
  Everybody interested in the topic should watch this video (it's just an animated graph, no music). You will get a better intuition for the lifetime of orbital debris, and the impact of various incidents, in a few minutes than in hours of reading.
- mcBesse 4y ago
  Wow, what a beautiful video. I really enjoyed trying to figure out what events and phenomena the different shapes/patterns in the diagram represent.
rzimmerman 4y ago
I didn't mean to imply orbit debris isn't a real problem. But for the low end of LEO: - Most debris deorbits naturally in a few years. Any debris causing events or accumulation naturally clears out in a reasonable time frame. It's not like debris at 800-2000km which is the real "Kessler Syndrome" concern where it takes decades or centuries. - Debris mitigation efforts that are already in place are effective. Limiting debris release during launch and deployments has had a huge positive impact over the last few decades. - "Traffic control" is a lot easier at these altitudes and debris in this range is well tracked. Obviously this doesn't extend to small stuff (<5cm), but due to active mitigation and natural decay this is less of an issue. Also ground radars are getting better and can actually see a lot of these objects now.

hinkley 4y ago

In this case it's policy reflecting Little's Law: population = arrival rate X duration of visit If suddenly someone wants to launch twice as many satellites, you either have to reduce tenancy or accept a higher population in the system. If you have a policy that's at most 25 years and a lot of satellites de-orbit in say 15 years on average, you can still triple your launches by pulling that down to 5. I am worried though, do we really build satellites that are expected to only work for 5 years? Are we disincentivizing people from building 20 year satellites this way?

Fatnino 4y ago
I assume it means deorbit within 5 years after the satellite is decommissioned.
ntrz 4y ago
The article says "5 years after completing their mission", not 5 years after launch.
- hahajk 4y ago
  time to assign 25 year missions to satellites built to last 10 years!
  - simonh 4y ago
    Every mission has to pass FCC approval, and we're just discussing a super high level gloss of the rules. Thee's no way that would pass, so that's really not an issue.
- hinkley 4y ago
  Wait, really? What orbital mechanics take five years to achieve? Lunar assisted orbital insertion burns only take a year or two, right? Why wouldn’t the deorbit burn start the day after decommissioning?
  - zardo 4y ago
    If it takes 5 years, there is no deorbit burn.

bryanlarsen 4y ago

Debris does not accumulate in LEO, it reenters naturally. This isn't like plastic waste, it's more like organic waste that naturally decays. Sometimes the law says you have to clean up organic waste, but sometimes it's better to let it rot on its own.

mikeyouse 4y ago
The timeframe varies widely based on the shape of the object and the altitude. There are something like 5 orders of magnitude pressure difference between an object at 100km and one at 500km which is the difference between deorbiting in days vs years.
- bryanlarsen 4y ago
  There's probably more than 5 orders of magnitude difference between throwing an apple core into the woods and a city's worth of sewage, but both are organic waste. I think the analogy is fairly sound.
  - haimez 4y ago
    While true, there’s also an asymmetry here in that a city can expand their landfill or sewer system capacity- orbital space has a fixed capacity
    - bryanlarsen 4y ago
      WTF? Space is incomprehendibly big. The number of potential landfill locations are very limited.
      - saghm 4y ago
        Isn't this thread discussing a very specific orbital range? The 450k-800k range is big, but I'm not sure I'd classify it as "incomprehensibly big".

MichaelCollins 4y ago

https://www.youtube.com/watch?v=mQT5aMa_7iI https://www.youtube.com/watch?v=mQT5aMa_7iI "Gabbard Diagram for Low Earth Orbit 1959-2021" See how the stuff in the lower left corner speeds up towards the lower left corner? That's low flying debris falling out of space.

wpietri 4y ago
I am generally allergic to video, but that was fascinating to watch. Thanks for sharing it.
ericbarrett 4y ago
Everybody interested in the topic should watch this video (it's just an animated graph, no music). You will get a better intuition for the lifetime of orbital debris, and the impact of various incidents, in a few minutes than in hours of reading.
mcBesse 4y ago
Wow, what a beautiful video. I really enjoyed trying to figure out what events and phenomena the different shapes/patterns in the diagram represent.

rzimmerman 4y ago

I didn't mean to imply orbit debris isn't a real problem. But for the low end of LEO: - Most debris deorbits naturally in a few years. Any debris causing events or accumulation naturally clears out in a reasonable time frame. It's not like debris at 800-2000km which is the real "Kessler Syndrome" concern where it takes decades or centuries. - Debris mitigation efforts that are already in place are effective. Limiting debris release during launch and deployments has had a huge positive impact over the last few decades. - "Traffic control" is a lot easier at these altitudes and debris in this range is well tracked. Obviously this doesn't extend to small stuff (<5cm), but due to active mitigation and natural decay this is less of an issue. Also ground radars are getting better and can actually see a lot of these objects now.