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> Amazon aims to have a 3,236-satellite constellation in orbit by 2029 Assuming Starlink is similar, are there any risks of "imprisonment" on Earth having ~8k

by exdsq 5y ago

> Amazon aims to have a 3,236-satellite constellation in orbit by 2029 Assuming Starlink is similar, are there any risks of "imprisonment" on Earth having ~8k low-orbit satellites flying around? In that they gravely affect efforts to fly Humans to the Moon/Mars?

ncallaway 5y ago
I haven't looked at the Amazon plans, but the risks of something like Kessler syndrome "trapping" us on earth from Starlink are low. The main reason is that the Starlink satellites fly in a very low altitude, such that even if they lose all control, they will deorbit in a few years. Which means, if something went horrifically wrong, the Starlink system debris would clear itself within a short period of time. It looks like the Amazon Project Kuiper satellites will be slightly higher up, but still have a natural orbital decay time of between 5-7 years. https://spacenews.com/amazon-lays-out-constellation-service-goals-deployment-and-deorbit-plans-to-fcc/ https://spacenews.com/amazon-lays-out-constellation-service-... So, the long term risks from these kinds of low-orbit mega constellations is fairly low. If anything goes catastrophically wrong we wait a decade and it's gone. I think personally, the longer term risks we should be wary of are medium altitude and geostationary orbits that won't naturally clear themselves for decades or centuries if something goes wrong.
T-A 5y ago
Suppose there were only 8000 cars in the world, evenly spread all over it (I'm being generous here, since 2/3 of Earth is covered by water). How likely would you be to ever see one?
- kamkazemoose 5y ago
  The starlink satellites are traveling a little bit faster than your average car though. They complete an orbit about every 100 minutes. So your 8000 satalites are covering much more ground than the same 8000 cars.
  - robbedpeter 5y ago
    At any given moment the distribution is similar, and we track and regulate the orbits, leaving swathes of space open. Everything about the satellites is engineered, including their orbits. Other countries have less stringent standards, resulting in more or less random de-orbits that can drop space junk anywhere in their path, but the US has a lot of forethought put into orbital standards. Space junk is an issue, but it's not anywhere near crisis level yet.
Rebelgecko 5y ago
The planned Starlink constellation is actually quite a bit bigger, but even if there's 20k satellites whizzing around it's not a huge problem. I think it's sometimes hard to reason about the vastness of space, but imagine if the planet Earth had exactly 20,000 cars on it's surface. Even if you crossed the street without looking, your odds of getting hit by a car would be incredibly low. And ofc in reality low earth orbit is bigger than the surface of the earth AND we know where every obstacle is located. If humanity ever gets to the point where we decide it's too crowded, most of these constellations are low enough that they'd naturally deorbit in less than a decade.
- robbedpeter 5y ago
  Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space. - Douglas Adams
runnerup 5y ago
Probably not. Even 500,000 sattelites would still leave more than enough space between them for whatever you want. The risk would be if many of them blew up or something, creating billions of tiny pieces of debris. In that scenario, we might just wait 5 years and then most of the debris will have burned up in the atmosphere. SpaceX satellites are around 550km attitude. If someone puts satellites higher than that, collision debris will last longer, the satellites' fuel will last longer so the satellites won't have to be replaced as often, but network latencies will be higher. Seems like 500-600km is the optimal zone for the primary constellations of internet satellites. Video showing decay of debris vs. its altitude. The "X" shape is because each debris is plotted twice, once at it's perigee and again at its apogee (describing the ellipse of the orbit as they generally are not perfectly circular) https://www.youtube.com/watch?v=mQT5aMa_7iI https://www.youtube.com/watch?v=mQT5aMa_7iI Higher altitude satellites would be a bigger concern but these aren't a big deal.
HideousKojima 5y ago
Starlink is at low enough orbits that even if the entire constellation spontaneously exploded all the debris would deorbit within ~5 years
gamegoblin 5y ago
On most days there are up to 20,000 airplanes (which are 100-1000x larger than satellites) in the sky. And the satellites, being at 100x higher altitude, are 100x more spread out than the airplanes. So just from a "unusable space" point of view, it's on the order of 10000x less of a problem than airplanes. The caveats here are the satellites are moving much, much faster than airplanes, and they stay in the sky much, much longer. But it's not really a huge problem unless stuff goes wrong and you get Kessler Syndrome. This is more of a risk with the higher constellations like Amazon's and OneWeb's than it is with SpaceX Starlink (which is in a low enough orbit to de-orbit all debris within a few years, rather than centuries).
- tgb 5y ago
  They're at 100x higher altitude relative to the sea level but nearly the same altitude relative to the Earth's center which is what matters here.
- jsnell 5y ago
  > And the satellites, being at 100x higher altitude, are 100x more spread out than the airplanes. This doesn't feel right. Shouldn't the right frame of reference be the distance to the center of the earth, not the sea level? Then it is not a 100x difference, but more like a 10% one.
  - karatekidd32v 5y ago
    Agreed rough math there doesn't seem right. Also, I wonder if there's an added benefit from the inverse square law here: https://en.wikipedia.org/wiki/Inverse-square_law https://en.wikipedia.org/wiki/Inverse-square_law
  - montenegrohugo 5y ago
    Here's the actual correct math: --- Area of sphere: 4πr^2 Airplane cruising height: ~10km Satellite orbit height: ~550km Radius of earth: 6371km thus, relative increase: (6371+550)/(6371+10) = 1.084 = 8.4% increase Squared (because of first formula) that corresponds with a 1.084^2 = 1.175 = 17.5% increase in area. --- Still, a few caveats: 1. Earth is huge. 510.1 million km² is a lot of space (+20% at 550km altitude). We could have a million sats with each having more than 1km^2 to themselves. 2. Satellites orbit at different heights. Amazon's and SpaceX's satellites will not be on the same orbit. 3. Starlink satellites are at a sufficiently low altitude that Kessler Syndrom is not a problem; even if they all simultaneously turned into millions of pieces of dead debris at the same time, the atmospheric drag would make them lower their orbits and burn up in just a few months.
johannes1234321 5y ago
There are two probable problems: a) debris damaging other satellites or space stations. There currently is no proper liability currently and different monitoring systems are still in development b) astronomy from earth will see problems. As long as they are on their orbits there is enough space (haha) and if they don't cause conflict with radio frequencies they also don't cause issues
gpm 5y ago
What you're asking about is basically https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikipedia.org/wiki/Kessler_syndrome In general the question of collision risk and debris is something evaluated for every launch/constellation. Starlink, for example, mostly avoids it being an issue by flying so low that debris quickly falls to earth and burns up in the atmosphere (they also design their satellites to fully burn up in the atmosphere). On the flip sides Starlink is planning on an order of magnitude more satellites than this. Even the worst case though doesn't really impact humans ability to fly to the moon/mars. You can make low earth orbit relatively unusable because there is a high collision risk if you hang out there for a year, but you should basically always be able to fly through low earth orbit to a higher orbit with negligible collision risk.
kiba 5y ago
You quoted that Amazon planned to have 3,236 satellites. Yet, SpaceX already launched 1730 satellites, 1630 of which are active, with a planned constellation of 12,000 satellites.[1] Amazon's Kuiper Systems hadn't even launched yet, and they're going with ULA for their first launch, which AFAIK, is much more expensive than SpaceX, with only 9 satellites as opposed to 60 satellites at a time.[2] [1] See https://en.wikipedia.org/wiki/Starlink https://en.wikipedia.org/wiki/Starlink [2] See https://en.wikipedia.org/wiki/Kuiper_Systems https://en.wikipedia.org/wiki/Kuiper_Systems
- tigershark 5y ago
  And they applied for permission to launch additional 30k satellites, bringing the total to 42k. Amazon Kuiper is a toy by comparison..
- SEJeff 5y ago
  And if/when SpaceX finishes Starship plus Superheavy, SpaceX will be launching up to 400 satellites per launch. Also, they've submitted authorization for up to 42,000 total starlink satellites: https://spacenews.com/spacex-submits-paperwork-for-30000-more-starlink-satellites/ https://spacenews.com/spacex-submits-paperwork-for-30000-mor...
bjacobt 5y ago
pardon the dumb question - how do rockets from spacex, etc avoid crashing into a satellite on its way up? Is there a way to keep track of all the satellites and debris in space and time the launch so there is a clear path?
- sgtnoodle 5y ago
  Yes, there is a database and radar tracking stations, and they'll avoid launching if there's an increased chance of a collision. The density of satellites and debris in orbit is so low in absolute terms, though, that the probability of any given rocket colliding is negligible even if launching totally blindly. Most launches are timed for minimizing fuel to achieve the desired orbit, and there's only a few seconds of wiggle room for a launch window. So, a particular launch window may be preferred over another depending on the relative probability of a collision. Nobody is explicitly timing their launches or ascent profile with regard to other satellites other than for space stations and other explicit destinations. Most launches the rocket just gets the satellites up into roughly the right orbit, and then the satellites use their own propulsion systems to maneuver into precise orbits over several months.
- bagels 5y ago
  Short answer: yes. They do this thing called "COLA", Collision On Launch Assessment, an analysis of launch trajectory to ensure they it won't hit known objects.
- deleted 5y ago
  [deleted]
SEJeff 5y ago
No. This wouldn't happen as space is much bigger and there are far more airplanes today in the sky than satellites with a higher more distant apart orbit. These low earth orbit constellations will naturally experience orbital decay and at the end of their useful life will simply burn up on re-entry. They're explicitly designed to prevent Kessler Syndrome: See also: https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikipedia.org/wiki/Kessler_syndrome
bagels 5y ago
There are already approximately 250,000 objects in low earth orbit 2cm and up. The risk from these constellations isn't from the satellites themselves directly, but from Kessler syndrome if they start getting smashed by untracked debris.
gorgoiler 5y ago
Atmospheric drag brings down anything below 800km: https://www.esa.int/Safety_Security/Space_Debris/About_space_debris https://www.esa.int/Safety_Security/Space_Debris/About_space... Starlink operates at 550km altitude: https://en.wikipedia.org/wiki/Starlink#Launches https://en.wikipedia.org/wiki/Starlink#Launches
- bagels 5y ago
  At 800km it can take a long time (decades)

by exdsq 5y ago

ncallaway 5y ago

I haven't looked at the Amazon plans, but the risks of something like Kessler syndrome "trapping" us on earth from Starlink are low. The main reason is that the Starlink satellites fly in a very low altitude, such that even if they lose all control, they will deorbit in a few years. Which means, if something went horrifically wrong, the Starlink system debris would clear itself within a short period of time. It looks like the Amazon Project Kuiper satellites will be slightly higher up, but still have a natural orbital decay time of between 5-7 years. https://spacenews.com/amazon-lays-out-constellation-service-goals-deployment-and-deorbit-plans-to-fcc/ https://spacenews.com/amazon-lays-out-constellation-service-... So, the long term risks from these kinds of low-orbit mega constellations is fairly low. If anything goes catastrophically wrong we wait a decade and it's gone. I think personally, the longer term risks we should be wary of are medium altitude and geostationary orbits that won't naturally clear themselves for decades or centuries if something goes wrong.

T-A 5y ago

Suppose there were only 8000 cars in the world, evenly spread all over it (I'm being generous here, since 2/3 of Earth is covered by water). How likely would you be to ever see one?

kamkazemoose 5y ago
The starlink satellites are traveling a little bit faster than your average car though. They complete an orbit about every 100 minutes. So your 8000 satalites are covering much more ground than the same 8000 cars.
- robbedpeter 5y ago
  At any given moment the distribution is similar, and we track and regulate the orbits, leaving swathes of space open. Everything about the satellites is engineered, including their orbits. Other countries have less stringent standards, resulting in more or less random de-orbits that can drop space junk anywhere in their path, but the US has a lot of forethought put into orbital standards. Space junk is an issue, but it's not anywhere near crisis level yet.

Rebelgecko 5y ago

The planned Starlink constellation is actually quite a bit bigger, but even if there's 20k satellites whizzing around it's not a huge problem. I think it's sometimes hard to reason about the vastness of space, but imagine if the planet Earth had exactly 20,000 cars on it's surface. Even if you crossed the street without looking, your odds of getting hit by a car would be incredibly low. And ofc in reality low earth orbit is bigger than the surface of the earth AND we know where every obstacle is located. If humanity ever gets to the point where we decide it's too crowded, most of these constellations are low enough that they'd naturally deorbit in less than a decade.

robbedpeter 5y ago
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space. - Douglas Adams

runnerup 5y ago

Probably not. Even 500,000 sattelites would still leave more than enough space between them for whatever you want. The risk would be if many of them blew up or something, creating billions of tiny pieces of debris. In that scenario, we might just wait 5 years and then most of the debris will have burned up in the atmosphere. SpaceX satellites are around 550km attitude. If someone puts satellites higher than that, collision debris will last longer, the satellites' fuel will last longer so the satellites won't have to be replaced as often, but network latencies will be higher. Seems like 500-600km is the optimal zone for the primary constellations of internet satellites. Video showing decay of debris vs. its altitude. The "X" shape is because each debris is plotted twice, once at it's perigee and again at its apogee (describing the ellipse of the orbit as they generally are not perfectly circular) https://www.youtube.com/watch?v=mQT5aMa_7iI https://www.youtube.com/watch?v=mQT5aMa_7iI Higher altitude satellites would be a bigger concern but these aren't a big deal.

HideousKojima 5y ago

Starlink is at low enough orbits that even if the entire constellation spontaneously exploded all the debris would deorbit within ~5 years

gamegoblin 5y ago

On most days there are up to 20,000 airplanes (which are 100-1000x larger than satellites) in the sky. And the satellites, being at 100x higher altitude, are 100x more spread out than the airplanes. So just from a "unusable space" point of view, it's on the order of 10000x less of a problem than airplanes. The caveats here are the satellites are moving much, much faster than airplanes, and they stay in the sky much, much longer. But it's not really a huge problem unless stuff goes wrong and you get Kessler Syndrome. This is more of a risk with the higher constellations like Amazon's and OneWeb's than it is with SpaceX Starlink (which is in a low enough orbit to de-orbit all debris within a few years, rather than centuries).

tgb 5y ago
They're at 100x higher altitude relative to the sea level but nearly the same altitude relative to the Earth's center which is what matters here.
jsnell 5y ago
> And the satellites, being at 100x higher altitude, are 100x more spread out than the airplanes. This doesn't feel right. Shouldn't the right frame of reference be the distance to the center of the earth, not the sea level? Then it is not a 100x difference, but more like a 10% one.
- karatekidd32v 5y ago
  Agreed rough math there doesn't seem right. Also, I wonder if there's an added benefit from the inverse square law here: https://en.wikipedia.org/wiki/Inverse-square_law https://en.wikipedia.org/wiki/Inverse-square_law
- montenegrohugo 5y ago
  Here's the actual correct math: --- Area of sphere: 4πr^2 Airplane cruising height: ~10km Satellite orbit height: ~550km Radius of earth: 6371km thus, relative increase: (6371+550)/(6371+10) = 1.084 = 8.4% increase Squared (because of first formula) that corresponds with a 1.084^2 = 1.175 = 17.5% increase in area. --- Still, a few caveats: 1. Earth is huge. 510.1 million km² is a lot of space (+20% at 550km altitude). We could have a million sats with each having more than 1km^2 to themselves. 2. Satellites orbit at different heights. Amazon's and SpaceX's satellites will not be on the same orbit. 3. Starlink satellites are at a sufficiently low altitude that Kessler Syndrom is not a problem; even if they all simultaneously turned into millions of pieces of dead debris at the same time, the atmospheric drag would make them lower their orbits and burn up in just a few months.

johannes1234321 5y ago

There are two probable problems: a) debris damaging other satellites or space stations. There currently is no proper liability currently and different monitoring systems are still in development b) astronomy from earth will see problems. As long as they are on their orbits there is enough space (haha) and if they don't cause conflict with radio frequencies they also don't cause issues

gpm 5y ago

What you're asking about is basically https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikipedia.org/wiki/Kessler_syndrome In general the question of collision risk and debris is something evaluated for every launch/constellation. Starlink, for example, mostly avoids it being an issue by flying so low that debris quickly falls to earth and burns up in the atmosphere (they also design their satellites to fully burn up in the atmosphere). On the flip sides Starlink is planning on an order of magnitude more satellites than this. Even the worst case though doesn't really impact humans ability to fly to the moon/mars. You can make low earth orbit relatively unusable because there is a high collision risk if you hang out there for a year, but you should basically always be able to fly through low earth orbit to a higher orbit with negligible collision risk.

kiba 5y ago

You quoted that Amazon planned to have 3,236 satellites. Yet, SpaceX already launched 1730 satellites, 1630 of which are active, with a planned constellation of 12,000 satellites.[1] Amazon's Kuiper Systems hadn't even launched yet, and they're going with ULA for their first launch, which AFAIK, is much more expensive than SpaceX, with only 9 satellites as opposed to 60 satellites at a time.[2] [1] See https://en.wikipedia.org/wiki/Starlink https://en.wikipedia.org/wiki/Starlink [2] See https://en.wikipedia.org/wiki/Kuiper_Systems https://en.wikipedia.org/wiki/Kuiper_Systems

tigershark 5y ago
And they applied for permission to launch additional 30k satellites, bringing the total to 42k. Amazon Kuiper is a toy by comparison..
SEJeff 5y ago
And if/when SpaceX finishes Starship plus Superheavy, SpaceX will be launching up to 400 satellites per launch. Also, they've submitted authorization for up to 42,000 total starlink satellites: https://spacenews.com/spacex-submits-paperwork-for-30000-more-starlink-satellites/ https://spacenews.com/spacex-submits-paperwork-for-30000-mor...

bjacobt 5y ago

pardon the dumb question - how do rockets from spacex, etc avoid crashing into a satellite on its way up? Is there a way to keep track of all the satellites and debris in space and time the launch so there is a clear path?

sgtnoodle 5y ago
Yes, there is a database and radar tracking stations, and they'll avoid launching if there's an increased chance of a collision. The density of satellites and debris in orbit is so low in absolute terms, though, that the probability of any given rocket colliding is negligible even if launching totally blindly. Most launches are timed for minimizing fuel to achieve the desired orbit, and there's only a few seconds of wiggle room for a launch window. So, a particular launch window may be preferred over another depending on the relative probability of a collision. Nobody is explicitly timing their launches or ascent profile with regard to other satellites other than for space stations and other explicit destinations. Most launches the rocket just gets the satellites up into roughly the right orbit, and then the satellites use their own propulsion systems to maneuver into precise orbits over several months.
bagels 5y ago
Short answer: yes. They do this thing called "COLA", Collision On Launch Assessment, an analysis of launch trajectory to ensure they it won't hit known objects.
deleted 5y ago
[deleted]

SEJeff 5y ago

No. This wouldn't happen as space is much bigger and there are far more airplanes today in the sky than satellites with a higher more distant apart orbit. These low earth orbit constellations will naturally experience orbital decay and at the end of their useful life will simply burn up on re-entry. They're explicitly designed to prevent Kessler Syndrome: See also: https://en.wikipedia.org/wiki/Kessler_syndrome https://en.wikipedia.org/wiki/Kessler_syndrome

bagels 5y ago

There are already approximately 250,000 objects in low earth orbit 2cm and up. The risk from these constellations isn't from the satellites themselves directly, but from Kessler syndrome if they start getting smashed by untracked debris.

gorgoiler 5y ago

Atmospheric drag brings down anything below 800km: https://www.esa.int/Safety_Security/Space_Debris/About_space_debris https://www.esa.int/Safety_Security/Space_Debris/About_space... Starlink operates at 550km altitude: https://en.wikipedia.org/wiki/Starlink#Launches https://en.wikipedia.org/wiki/Starlink#Launches

bagels 5y ago
At 800km it can take a long time (decades)