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Does anyone have any ballpark figures on the decay time of the debris blanket we're putting around the earth? Say we plunge ourselves into nuclear or biological

Does anyone have any ballpark figures on the decay time of the debris blanket we're putting around the earth? Say we plunge ourselves into nuclear or biological anarchy and society regresses 50.000 years... will our descendants still suffer our shortsightedness?

exporectomy 5y ago
It seems to be only a couple of years (losing 100m altitude per day [1] ) for the ISS to fall out of orbit if it was left alone. I guess space debris in the same orbit would be the same. [1] https://space.stackexchange.com/questions/9482/how-long-would-iss-stay-in-orbit-if-it-didnt-get-reboosts https://space.stackexchange.com/questions/9482/how-long-woul... Higher orbits would last essentially forever though. These tiny objects aren't that disastrous either. From what I understand, the insulating blankets destroy them and dissipate their energy, limiting damage to the underlying structure.
adrianN 5y ago
That strongly depends on the altitude. LEO still has fairly strong atmospheric drag, so trash from there lives on the order of years. Higher up, say geostationary, the drag is very small, so trash is stable for hundreds or thousands of years. But then again, there is a lot more space the further out you go.
- bagels 5y ago
  Decades or centuries above 1000km...
- ryankrage77 5y ago
  > there is a lot more space the further out you go. This made curious how much more space you get, so I did some maths. According to Wikipedia, LEO is basically anything below 2000KM, so we'll call 1000KM the average. Geostationary orbit is apparently 35,786KM above the surface (at the equator. The earth is not a perfect sphere). The diameter of the earth is 12,742KM, making the circumference of this LEO ~43,171KM Let's say there's 10KM between every piece of debris, meaning you can fit 4317 piece of debris into this orbit. (that's not how it really works of course, this is just an arbitary number to use as a comparison). At geostationary orbit, the circumference is ~152,000KM, meaning the same 4317 pieces of debris would now be ~35KM apart instead. Or you could fit 15,200 peices of debris in, still spaced 10KM apart. Or you could say you have ~252% more space at the higher orbit.
DocTomoe 5y ago
This depends on the orbit of the debris and the probability of getting hit (you are unlikely to ever get to 0, and technically, it makes little difference if you got a man-made bolt hitting you at 1km/s, or a naturally-occuring space rock of similar mass). Most spacefaring countries have adopted a rule of getting low-earth-orbit objects out of space within 25 years of their mission's end-of-life. Some (though relatively few) objects are in high orbits. These will take millenia - the good news is that they are also relatively slow, which makes them easier to avoid. And then we have people shooting their sportscar into space on an orbit that will last virtually indefinitely.
- rocqua 5y ago
  The tesla is not in earth orbit afaik. Though it is on an earth intercept orbit i guess.
- shkkmo 5y ago
  > the good news is that they are also relatively slow, which makes them easier to avoid. This is not true. Higher orbits do circle the earth less frequently...but that is not because they are slower, but because they have further to go. In fact, the higher your orbit, the faster you are going.
Heliosmaster 5y ago
I found the gif in this Reddit post very interesting in that regard: https://www.reddit.com/r/dataisbeautiful/comments/lczisw/oc_satellite_breakup_events_and_space_debris_in/ https://www.reddit.com/r/dataisbeautiful/comments/lczisw/oc_... You can see the effect of atmospheric drag and resulting decay for LEO objects. And how catastrophic collisions are. Edit: And original source https://mads-hatters.github.io/ https://mads-hatters.github.io/
jillesvangurp 5y ago
Probably if we stopped launching new stuff, most of it would be gone in a few years to a few decades. Most of the orbits of this stuff aren't that stable. Most satellites have decaying orbits that need correcting regularly. I have to object the phrasing debris blanket here though. If you compare low orbit (where most of this stuff is) to the combined surface areas of our oceans, it's larger because it also includes the surface area of our landmass and you have to take into account the larger sphere radius of an extra 100km. Just driving the point home that it's a pretty big surface area if you assume it's effectively 2D. Which of course it isn't. If you then add the third dimension with say a couple of hundred kilometer that make up low earth orbit, the probability of hitting anything drops pretty low. That stuff should be extremely rare. There's a bit of debris in orbit. Some of the larger bits, we track. Of course if you do hit something, the speed differences mean a collision can do some real damage. Compared to naturally occurring stuff (meteorites, space rocks, etc) it's not that much of an additional risk. ISS does get hit by that stuff occasionally. A bigger rock (pebble sized) could do a lot of damage. I don't think that has happened yet. It's a non zero risk but an acceptable one.
- amelius 5y ago
  I think the main problem is that the stuff is moving so fast wrt eachother that a particle isn't 0-dimensional but effectively becomes 1-dimensional, a long trace. So you'd have to think of the debris as miles long strands, and suddenly it seems quite likely to hit one.
- shkkmo 5y ago
  > Compared to naturally occurring stuff (meteorites, space rocks, etc) it's not that much of an additional risk. Do you have a citation for this?
qbasic_forever 5y ago
If it looks like we're heading down that path, we should send a probe with a complete history of our race, all of our known science, etc. to a lagrange point for safe keeping.
colechristensen 5y ago
Anywhere from “later this hour” to “not until the sun grows in its demise to engulf the earths orbit entirely” I’m fairly hopeful that it is a problem with a solution once there is adequate motivation.

exporectomy 5y ago

It seems to be only a couple of years (losing 100m altitude per day [1] ) for the ISS to fall out of orbit if it was left alone. I guess space debris in the same orbit would be the same. [1] https://space.stackexchange.com/questions/9482/how-long-would-iss-stay-in-orbit-if-it-didnt-get-reboosts https://space.stackexchange.com/questions/9482/how-long-woul... Higher orbits would last essentially forever though. These tiny objects aren't that disastrous either. From what I understand, the insulating blankets destroy them and dissipate their energy, limiting damage to the underlying structure.

adrianN 5y ago

That strongly depends on the altitude. LEO still has fairly strong atmospheric drag, so trash from there lives on the order of years. Higher up, say geostationary, the drag is very small, so trash is stable for hundreds or thousands of years. But then again, there is a lot more space the further out you go.

bagels 5y ago
Decades or centuries above 1000km...
ryankrage77 5y ago
> there is a lot more space the further out you go. This made curious how much more space you get, so I did some maths. According to Wikipedia, LEO is basically anything below 2000KM, so we'll call 1000KM the average. Geostationary orbit is apparently 35,786KM above the surface (at the equator. The earth is not a perfect sphere). The diameter of the earth is 12,742KM, making the circumference of this LEO ~43,171KM Let's say there's 10KM between every piece of debris, meaning you can fit 4317 piece of debris into this orbit. (that's not how it really works of course, this is just an arbitary number to use as a comparison). At geostationary orbit, the circumference is ~152,000KM, meaning the same 4317 pieces of debris would now be ~35KM apart instead. Or you could fit 15,200 peices of debris in, still spaced 10KM apart. Or you could say you have ~252% more space at the higher orbit.

DocTomoe 5y ago

This depends on the orbit of the debris and the probability of getting hit (you are unlikely to ever get to 0, and technically, it makes little difference if you got a man-made bolt hitting you at 1km/s, or a naturally-occuring space rock of similar mass). Most spacefaring countries have adopted a rule of getting low-earth-orbit objects out of space within 25 years of their mission's end-of-life. Some (though relatively few) objects are in high orbits. These will take millenia - the good news is that they are also relatively slow, which makes them easier to avoid. And then we have people shooting their sportscar into space on an orbit that will last virtually indefinitely.

rocqua 5y ago
The tesla is not in earth orbit afaik. Though it is on an earth intercept orbit i guess.
shkkmo 5y ago
> the good news is that they are also relatively slow, which makes them easier to avoid. This is not true. Higher orbits do circle the earth less frequently...but that is not because they are slower, but because they have further to go. In fact, the higher your orbit, the faster you are going.

Heliosmaster 5y ago

I found the gif in this Reddit post very interesting in that regard: https://www.reddit.com/r/dataisbeautiful/comments/lczisw/oc_satellite_breakup_events_and_space_debris_in/ https://www.reddit.com/r/dataisbeautiful/comments/lczisw/oc_... You can see the effect of atmospheric drag and resulting decay for LEO objects. And how catastrophic collisions are. Edit: And original source https://mads-hatters.github.io/ https://mads-hatters.github.io/

jillesvangurp 5y ago

Probably if we stopped launching new stuff, most of it would be gone in a few years to a few decades. Most of the orbits of this stuff aren't that stable. Most satellites have decaying orbits that need correcting regularly. I have to object the phrasing debris blanket here though. If you compare low orbit (where most of this stuff is) to the combined surface areas of our oceans, it's larger because it also includes the surface area of our landmass and you have to take into account the larger sphere radius of an extra 100km. Just driving the point home that it's a pretty big surface area if you assume it's effectively 2D. Which of course it isn't. If you then add the third dimension with say a couple of hundred kilometer that make up low earth orbit, the probability of hitting anything drops pretty low. That stuff should be extremely rare. There's a bit of debris in orbit. Some of the larger bits, we track. Of course if you do hit something, the speed differences mean a collision can do some real damage. Compared to naturally occurring stuff (meteorites, space rocks, etc) it's not that much of an additional risk. ISS does get hit by that stuff occasionally. A bigger rock (pebble sized) could do a lot of damage. I don't think that has happened yet. It's a non zero risk but an acceptable one.

amelius 5y ago
I think the main problem is that the stuff is moving so fast wrt eachother that a particle isn't 0-dimensional but effectively becomes 1-dimensional, a long trace. So you'd have to think of the debris as miles long strands, and suddenly it seems quite likely to hit one.
shkkmo 5y ago
> Compared to naturally occurring stuff (meteorites, space rocks, etc) it's not that much of an additional risk. Do you have a citation for this?

qbasic_forever 5y ago

If it looks like we're heading down that path, we should send a probe with a complete history of our race, all of our known science, etc. to a lagrange point for safe keeping.

colechristensen 5y ago

Anywhere from “later this hour” to “not until the sun grows in its demise to engulf the earths orbit entirely” I’m fairly hopeful that it is a problem with a solution once there is adequate motivation.