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From the article: > "Collisions are proportional to the square of the number of things in orbit," McDowell told Space.com. "That is to say, if you have 10 time

by jnxx 5y ago

From the article: > "Collisions are proportional to the square of the number of things in orbit," McDowell told Space.com. "That is to say, if you have 10 times as many satellites, you're going to get 100 times as many collisions. Unfortunately, any collision also increases the number of things in orbit, by breaking up spacecraft. The collision between Kosmos-2251 and Iridium 33 generated 1,300 pieces of debris in orbit. The collision between Object 48078 from Russia's Zenit-2 rocket and China's Yunhai 1-02 generated 37 known debris objects, and likely a lot more smaller untracked objects. This is likely to lead to Kessler Syndrome, a chain reaction of collisions once the density of debris fragments above a certain weight passes a critical density: http://aquarid.physics.uwo.ca/kessler/Critical%20Density%201991.pdf http://aquarid.physics.uwo.ca/kessler/Critical%20Density%201... Unless satellites are brought back to Earth, the likely path of development is that Earth will get a layer of satellite debris which makes a a good part of satellite technology basically infeasible (and any spaceflight much more dangerous).

didericis 5y ago
If things got that bad I think there’d be increased incentive to invent something to clean it up. It’s a very hard problem, but it doesn’t seem impossible to deal with, I think it just requires fairly extreme intervention. I think most orbits naturally decay, too, so there’d be a time limit even if we couldn’t clean things up.
- i_haz_rabies 5y ago
  I wonder if there isn't already a team at SpaceX or something working on a few moonshot solutions.
  - bell-cot 5y ago
    SpaceX probably has several rough-draft plans for mopping up dangerous orbiting debris sitting in a filing cabinet somewhere. BUT - So long as SpaceX avoids being seen as "at fault", any Kessler sh*t-storms that occur are likely to prove huge opportunities for SpaceX, and huge problems for all of their competitors. Most debris-storm clean-up ideas require plenty of launches, to get the Wonder Widgets and Space Squeegees into orbit. Likewise the replacements for all the smashed satellites. Which replacements may be substantially heavier, due to beefed-up propulsion systems for debris dodging, armor protection around their vitals, etc. And guess what company is the world's miles-ahead provider of low-cost orbital launch services, with an easy path to oh-so-profitable scaling up?
    - datameta 5y ago
      It's an appealing narrative but Kessler Syndrome is something that would stand in the way of Musk's primary mission of getting us set up on Mars. So even if one holds the belief that he is highly profit motivated beyond the scope of funding his main project, it should be evident that this would divert much needed resources and time that put a hamper on the Mars timeline. I highly recommend the Starbase tour with Everyday Astronaut, especially Part 3 [0], for perhaps the best existing look into his thought process and development philosophy. Throughout the tour he comes across as humble, ready to incorporate ideas and truly entertain questions from a studied layman. What also really speaks for him is how he is treated by his employees, how he treats them, and how involved he is with the ground level of the operation. It is evident to what deep level of urgency and importance he approaches the undertaking that SpaceX is and so I do not believe they would seek to profit from controlling Kessler Syndrome. [0] https://youtu.be/9Zlnbs-NBUI https://youtu.be/9Zlnbs-NBUI
      - bell-cot 5y ago
        > ...and so I do not believe they would seek to profit from controlling Kessler Syndrome. I get the feel that logic from /Hollywood/tropes/James_Bond/ is being assumed here. In a simplistic action movie, it's reasonable to say "IF $Charismatic_Corporate_Leader profited from $Bad_Thing happening, THEN he is Totally Evil, secretly controls $Bad_Thing, and caused it to happening as part of his Evil Plans". The Real World(tm) isn't like that. Elan and SpaceX don't control Kessler Syndrome. They are not the U.N. Space Police*. (Cripes, they can't even get timely launch approvals from the FAA, or a more sensible exclusion zone at the Cape!) "Failing" to have detailed plans & preparations for an orbital sh*t-storm - IF they don't cause it, and aren't badly damaged by it - is no more evil than "failing" to donate $75 million to African famine relief. *Not a real thing. The point is that SpaceX ain't the law, ain't the sovereign, and ain't on some government contract to provide space emergency services & disaster relief. (FWIW, I found the first two Starbase tour videos more interesting. Admittedly, they had the advantage of being ~3x longer.) (Edit - formatting issue from an un-escaped '*' character.)
        datameta 5y ago
- LeifCarrotson 5y ago
  It sounds like you're shrugging off the problem, ignoring the advice of experts who are suggesting we need to make changes now and deciding instead that you'll ask those same experts to fix the problem later when their predictions come true; allowing intuition, incentives to continue current behavior, and resistance to change to determine your course of action. But intuitions fail when it comes to how mind-bogglingly big and fast space is. The volume you might need to sift through has an area equal to the surface of the entire planet and a height of thousands of kilometers. The objects you're trying to grab are moving at >20,000 km/hr. Low orbits do decay naturally in a few decades, yes, but MEO and GEO orbits can take thousands to millions of years to decay. It's like being a war zone where bullets that are fired continue ricocheting through the air for decades, and these objects are moving ten times faster than a typical bullet (and may weigh hundreds of kg). We're laying a minefield and not even keeping track of where the mines are laid. The least we can do is to keep track of and share the satellite orbits.
  - didericis 5y ago
    I’m not shrugging off the problem, and people should be extremely wary to the point where I think it makes sense to portray the situation as if we would be locked to earth forever if it got out of hand so cleanup is never necessary. However I think people underestimate ingenuity and the ability to solve the cleanup problem if we really have to. I don’t know how much effort has really be invested in hitting that cleanup problem as hard as possible, as most discussion about it currently is theoretical, and there isn’t a lot of financial benefit to researching it. If it starts preventing launches, then the incentives to hit the problem harder increase. It’d obviously be better not to be forced into figuring out whether that problem is solvable, my point is it’s not set in stone that it’s an unsolvable problem, and the incentives are currently such that I don’t think we can consider possible solutions adequately explored.
  - didericis 5y ago
    I think we’re also currently tracking most existing debris fairly comprehensively/that seems to be the part of the problem currently receiving the most attention, and rightfully so. As of right now tracking debris and trying not to create more of it seems like the best way forward
PeterisP 5y ago
All the low earth orbits decay due to low but meaningful resistance from the thin atmosphere; satellites like the SpaceX Starlink essentially are continuously "brough back to Earth" unless they periodically boost themselves up to maintain orbit height.
- tgsovlerkhgsel 5y ago
  How quickly though? Given the size of the constellations that are currently being launched, could all of LEO become an all-destroying debris cloud, forcing us out of LEO for a year or so until it has decayed? Possibly not a disaster now, but once people start relying on Starlink & co, it could be.
  - lutorm 5y ago
    The orbital decay time depends on the ballistic coefficient of the body. This scales as mass/area, so is lower for small objects, meaning they decay faster. If the decay time for a Starlink satellite is a couple years, fragments from a collision will deorbit much faster.
    - dave333 5y ago
      Since all debris will return to near the collision point approximately every 90 minutes, there will be further collisions of bits of debris that will tend to reduce the size of the bits of debris and speed up the decay. This will be more pronounced if the original objects that collided have orbit planes that are nearer orthogonal.
- renox 5y ago
  Unfortunately that's too simple: imagine a collusion with a low orbit satellite which explodes, some part of the debris will be boosted to an higher height..
  - PeterisP 5y ago
    No, that's not really how orbits work - after a collision or explosion, the orbit of every created shard will still pass through the point of collision, so if a satellite in circular LEO gets exploded, much of the debris will be boosted to a more elliptical orbit where the apogee may be higher, potentially much higher, but the perigee - where the majority of the drag happens, in a very nonlinear manner - will be lower than that LEO orbit or at the very worst case the same as it, having an elliptical orbit that comes down to the atmosphere, slowing down at every iteration. There's no physical way for a single event to bring something up from a low circular orbit to a higher orbit that's fully out of that low altitude zone, that requires circularization for which spaceships need to do another burn at the opposite (high) point of the orbit. If some circular orbit is in a LEO "gonna burn up soon" zone, then the debris from a crash there won't leave the zone because all the elliptical orbits that pass through points on that circle also have as much or more "gonna burn up soon" property.

by jnxx 5y ago

didericis 5y ago

If things got that bad I think there’d be increased incentive to invent something to clean it up. It’s a very hard problem, but it doesn’t seem impossible to deal with, I think it just requires fairly extreme intervention. I think most orbits naturally decay, too, so there’d be a time limit even if we couldn’t clean things up.

i_haz_rabies 5y ago
I wonder if there isn't already a team at SpaceX or something working on a few moonshot solutions.
- bell-cot 5y ago
  SpaceX probably has several rough-draft plans for mopping up dangerous orbiting debris sitting in a filing cabinet somewhere. BUT - So long as SpaceX avoids being seen as "at fault", any Kessler sh*t-storms that occur are likely to prove huge opportunities for SpaceX, and huge problems for all of their competitors. Most debris-storm clean-up ideas require plenty of launches, to get the Wonder Widgets and Space Squeegees into orbit. Likewise the replacements for all the smashed satellites. Which replacements may be substantially heavier, due to beefed-up propulsion systems for debris dodging, armor protection around their vitals, etc. And guess what company is the world's miles-ahead provider of low-cost orbital launch services, with an easy path to oh-so-profitable scaling up?
  - datameta 5y ago
    It's an appealing narrative but Kessler Syndrome is something that would stand in the way of Musk's primary mission of getting us set up on Mars. So even if one holds the belief that he is highly profit motivated beyond the scope of funding his main project, it should be evident that this would divert much needed resources and time that put a hamper on the Mars timeline. I highly recommend the Starbase tour with Everyday Astronaut, especially Part 3 [0], for perhaps the best existing look into his thought process and development philosophy. Throughout the tour he comes across as humble, ready to incorporate ideas and truly entertain questions from a studied layman. What also really speaks for him is how he is treated by his employees, how he treats them, and how involved he is with the ground level of the operation. It is evident to what deep level of urgency and importance he approaches the undertaking that SpaceX is and so I do not believe they would seek to profit from controlling Kessler Syndrome. [0] https://youtu.be/9Zlnbs-NBUI https://youtu.be/9Zlnbs-NBUI
    - bell-cot 5y ago
      > ...and so I do not believe they would seek to profit from controlling Kessler Syndrome. I get the feel that logic from /Hollywood/tropes/James_Bond/ is being assumed here. In a simplistic action movie, it's reasonable to say "IF $Charismatic_Corporate_Leader profited from $Bad_Thing happening, THEN he is Totally Evil, secretly controls $Bad_Thing, and caused it to happening as part of his Evil Plans". The Real World(tm) isn't like that. Elan and SpaceX don't control Kessler Syndrome. They are not the U.N. Space Police*. (Cripes, they can't even get timely launch approvals from the FAA, or a more sensible exclusion zone at the Cape!) "Failing" to have detailed plans & preparations for an orbital sh*t-storm - IF they don't cause it, and aren't badly damaged by it - is no more evil than "failing" to donate $75 million to African famine relief. *Not a real thing. The point is that SpaceX ain't the law, ain't the sovereign, and ain't on some government contract to provide space emergency services & disaster relief. (FWIW, I found the first two Starbase tour videos more interesting. Admittedly, they had the advantage of being ~3x longer.) (Edit - formatting issue from an un-escaped '*' character.)
      - datameta 5y ago
LeifCarrotson 5y ago
It sounds like you're shrugging off the problem, ignoring the advice of experts who are suggesting we need to make changes now and deciding instead that you'll ask those same experts to fix the problem later when their predictions come true; allowing intuition, incentives to continue current behavior, and resistance to change to determine your course of action. But intuitions fail when it comes to how mind-bogglingly big and fast space is. The volume you might need to sift through has an area equal to the surface of the entire planet and a height of thousands of kilometers. The objects you're trying to grab are moving at >20,000 km/hr. Low orbits do decay naturally in a few decades, yes, but MEO and GEO orbits can take thousands to millions of years to decay. It's like being a war zone where bullets that are fired continue ricocheting through the air for decades, and these objects are moving ten times faster than a typical bullet (and may weigh hundreds of kg). We're laying a minefield and not even keeping track of where the mines are laid. The least we can do is to keep track of and share the satellite orbits.
- didericis 5y ago
  I’m not shrugging off the problem, and people should be extremely wary to the point where I think it makes sense to portray the situation as if we would be locked to earth forever if it got out of hand so cleanup is never necessary. However I think people underestimate ingenuity and the ability to solve the cleanup problem if we really have to. I don’t know how much effort has really be invested in hitting that cleanup problem as hard as possible, as most discussion about it currently is theoretical, and there isn’t a lot of financial benefit to researching it. If it starts preventing launches, then the incentives to hit the problem harder increase. It’d obviously be better not to be forced into figuring out whether that problem is solvable, my point is it’s not set in stone that it’s an unsolvable problem, and the incentives are currently such that I don’t think we can consider possible solutions adequately explored.
- didericis 5y ago
  I think we’re also currently tracking most existing debris fairly comprehensively/that seems to be the part of the problem currently receiving the most attention, and rightfully so. As of right now tracking debris and trying not to create more of it seems like the best way forward

PeterisP 5y ago

All the low earth orbits decay due to low but meaningful resistance from the thin atmosphere; satellites like the SpaceX Starlink essentially are continuously "brough back to Earth" unless they periodically boost themselves up to maintain orbit height.

tgsovlerkhgsel 5y ago
How quickly though? Given the size of the constellations that are currently being launched, could all of LEO become an all-destroying debris cloud, forcing us out of LEO for a year or so until it has decayed? Possibly not a disaster now, but once people start relying on Starlink & co, it could be.
- lutorm 5y ago
  The orbital decay time depends on the ballistic coefficient of the body. This scales as mass/area, so is lower for small objects, meaning they decay faster. If the decay time for a Starlink satellite is a couple years, fragments from a collision will deorbit much faster.
  - dave333 5y ago
    Since all debris will return to near the collision point approximately every 90 minutes, there will be further collisions of bits of debris that will tend to reduce the size of the bits of debris and speed up the decay. This will be more pronounced if the original objects that collided have orbit planes that are nearer orthogonal.
renox 5y ago
Unfortunately that's too simple: imagine a collusion with a low orbit satellite which explodes, some part of the debris will be boosted to an higher height..
- PeterisP 5y ago
  No, that's not really how orbits work - after a collision or explosion, the orbit of every created shard will still pass through the point of collision, so if a satellite in circular LEO gets exploded, much of the debris will be boosted to a more elliptical orbit where the apogee may be higher, potentially much higher, but the perigee - where the majority of the drag happens, in a very nonlinear manner - will be lower than that LEO orbit or at the very worst case the same as it, having an elliptical orbit that comes down to the atmosphere, slowing down at every iteration. There's no physical way for a single event to bring something up from a low circular orbit to a higher orbit that's fully out of that low altitude zone, that requires circularization for which spaceships need to do another burn at the opposite (high) point of the orbit. If some circular orbit is in a LEO "gonna burn up soon" zone, then the debris from a crash there won't leave the zone because all the elliptical orbits that pass through points on that circle also have as much or more "gonna burn up soon" property.