If the shards are in the atmosphere, they'll fall to the ground immediately. Even the IIS at over 300km altitude needs a boost every now and then to maintain altitude due to the drag of the rarefied atmosphere that high up. Very few satellites are put in orbits below 300km because they'd only stay up for a few years or less.
Consider that 11,000 satellite-sized objects are spread over the surface of the earth-- given an entire lifetime to search, how many do you think you could find?
It helps a little to imagine it as people instead of objects. Imagine there are only 11,000 people on earth instead of 7 billion-- just the population of one small town, spread over all the oceans and all the continents. Do you think you would ever find even one of them?
Then consider that orbital height expands the "surface area" of this satellite spread by an enormous amount....the surface area of a sphere at LEO is substantially larger than the surface area of the earth. I don't know the exact numbers, but I know it's a huge difference.
So the odds of ever finding any would be substantially lower.
I don't think this is something we have to worry about, even if it was 100,000 satellites.
But...I'm not an expert on orbital mechanics. I could be wrong, for sure. Just seems suspect to me.
The problem is that these 11000 objects are moving among the existing ones. Some are nearly stationary on a geostationary orbit, while the LEO objects tend to zip around on wildly different orbits. So they are not sitting there, waiting to be found, but each object has a certain chance each orbit to hit some other object. These probabilities go up the more we put in orbit.
Bad explanation; the LEO and the Geostationary satellites will never ever bump into each other; they are in completely different orbits that never cross. Furthermore, we don't just randomly chuck these things into orbit without any thought or consideration. They do not 'have a certain chance each orbit' to hit something.
It's collisions that trigger a runaway Kessler syndrome. Collisions have happened before and they are a serious concern. Just ask the inhabitants of the space station, for example. Probability dictates that sooner or later, something or someone will run into you. I don't think Starlink is doing all that they can to safeguard their satellites, especially considering that managers were fired for not prioritizing quality over speed.
> Imagine there are only 11,000 people on earth instead of 7 billion-- just the population of one small town, spread over all the oceans and all the continents.
But not evenly. There are certain orbits that most satellites try to stay in.
> the surface area of a sphere at LEO is substantially larger than the surface area of the earth. I don't know the exact numbers, but I know it's a huge difference.
The surface area of the sphere is not much bigger, LEO starts a few hundred km up compared to the Earth's radius of thousands of km. Maybe 1.5x the surface area. But it expands in 3 dimensions: if the interesting part of LEO is 500km thick and a satellite takes up 10m of it from bottom to top, that's 50,000 concentric Earth-surfaces.
Then consider that orbital height expands the "surface area" of this satellite spread by an enormous amount....the surface area of a sphere at LEO is substantially larger than the surface area of the earth. I don't know the exact numbers, but I know it's a huge difference.
Surface area grows with the radius squared. Starlink are meant to be at (a max of) 1200km above the surface. Earth radius is 6371.
((6371 + 1200) / 6371)^2 = 1.41
There is 41% more surface area at their orbit than at sea level.
> The only real solution companies like SpaceX has when disposing of a satellite when it's outlived its usefulness is to let them get pulled into the atmosphere and burn up on re-entry, but when it comes to managing 12,000 of them at once (and 4,000 in higher orbits, where they're less likely to get pulled down naturally), how many will slip through the cracks?
This is the only real solution anyone has. It’s just not feasible to do anything else other than park the satellite in a graveyard orbit or deorbit it.
The entire premise of the article is daft and ignorant of basic orbital mechanics. The Starlink satellites will communicate with each other directly via laser. They can only do that by knowing very precisely where they and the other satellite are, so the whole constellation will have to be continuously tracked at high precision just to function at all.
Onjects in LEO don't really become space junk because there's enough atmosphere to force a natural decay of the orbit for most objects within a human lifetime.
This does not deserve a sensationalist depiction. Everyone in space industry, astronomy and even the public now thanks to this terrible movie Gravity knows about the Kessler effect.
Some thoughts:
- Putting 12000 big freezers (900 pounds at most) in orbit is never going to "crowd" the place; imagine these objects on Earth, then the claim that on a much higher radius sphere these could be seen at any point seems ridiculous.
(I am not speaking about speed or dangerosity, which even up the numbers a bit, or powerful light-emitting projects)
- In that sense, the video displayed is annoyingly misleading.
- The danger of the Kessler effect is a long term one, and as such it seems purely economic to me. Increasing the number of space debris will gradually increase the probability of collisions, and raise the costs of space industry, in an upwards trend that may at some point represent a real financial burden. This is the only question: at which point does it become economically interesting to tackle this problem, and are we not underestimating the future costs at this point ?
- My take is not yet, and SpaceX will do fine managing their 12000 space fridges.
It is also worth considering, that of the planned 12k satellites, only 4k will be in a higher orbit where long-living space junk can be created. The vast majority of the satellites will be in an orbit about 200 miles over ground where there is some minimal atmospheric drag, cleaning up any possible. Even without any other action taken, these satellites will reenter the atmosphere after 5-10 years on their own.
Those satellites in the higher orbits require some care though. They wouldn't deorbit on their own and any space junk from collisions would stay around an extremely long time. For those sent up by SpaceX, there would be plenty of space, but if there are enough competing companies, things could get quite crowded. Of all people though, I would think that Elon is the most considerate about long-term environmental impact. After all, he doesn't want to block the path for his own Mars rockets.
The USAF Space Command tracks orbital objects[0]. Adding more satellites would certainly increase their workload, but they regularly upgrade systems to handle it. Here's the ribbon cutting on Maui for one upgrade:
This si full FUD and I don’t known the author objective. Those satellite will be in low orbit where one of there big problem will be to keep theire orbit. Their end of Life depend on how much fuel they have, and when they have no more fuel they decay. Or takes only some months (or at most a des years for the ones in higher orbit) to burn in the athmospher.
The only problem Witness so much satelite in low orbit si tracking them during their life which us easy for thoses as they require precise tracking for being operational.
23 comments
[ 1.7 ms ] story [ 41.1 ms ] threadConsider that 11,000 satellite-sized objects are spread over the surface of the earth-- given an entire lifetime to search, how many do you think you could find?
It helps a little to imagine it as people instead of objects. Imagine there are only 11,000 people on earth instead of 7 billion-- just the population of one small town, spread over all the oceans and all the continents. Do you think you would ever find even one of them?
Then consider that orbital height expands the "surface area" of this satellite spread by an enormous amount....the surface area of a sphere at LEO is substantially larger than the surface area of the earth. I don't know the exact numbers, but I know it's a huge difference.
So the odds of ever finding any would be substantially lower.
I don't think this is something we have to worry about, even if it was 100,000 satellites.
But...I'm not an expert on orbital mechanics. I could be wrong, for sure. Just seems suspect to me.
But not evenly. There are certain orbits that most satellites try to stay in.
The surface area of the sphere is not much bigger, LEO starts a few hundred km up compared to the Earth's radius of thousands of km. Maybe 1.5x the surface area. But it expands in 3 dimensions: if the interesting part of LEO is 500km thick and a satellite takes up 10m of it from bottom to top, that's 50,000 concentric Earth-surfaces.
Surface area grows with the radius squared. Starlink are meant to be at (a max of) 1200km above the surface. Earth radius is 6371.
((6371 + 1200) / 6371)^2 = 1.41
There is 41% more surface area at their orbit than at sea level.
This is the only real solution anyone has. It’s just not feasible to do anything else other than park the satellite in a graveyard orbit or deorbit it.
Some thoughts:
- Putting 12000 big freezers (900 pounds at most) in orbit is never going to "crowd" the place; imagine these objects on Earth, then the claim that on a much higher radius sphere these could be seen at any point seems ridiculous. (I am not speaking about speed or dangerosity, which even up the numbers a bit, or powerful light-emitting projects)
- In that sense, the video displayed is annoyingly misleading.
- The danger of the Kessler effect is a long term one, and as such it seems purely economic to me. Increasing the number of space debris will gradually increase the probability of collisions, and raise the costs of space industry, in an upwards trend that may at some point represent a real financial burden. This is the only question: at which point does it become economically interesting to tackle this problem, and are we not underestimating the future costs at this point ?
- My take is not yet, and SpaceX will do fine managing their 12000 space fridges.
https://www.theguardian.com/science/blog/2013/nov/15/space-j...
Those satellites in the higher orbits require some care though. They wouldn't deorbit on their own and any space junk from collisions would stay around an extremely long time. For those sent up by SpaceX, there would be plenty of space, but if there are enough competing companies, things could get quite crowded. Of all people though, I would think that Elon is the most considerate about long-term environmental impact. After all, he doesn't want to block the path for his own Mars rockets.
https://www.youtube.com/watch?v=IwWby884p6I
Like most mountains in Hawaii, it's on top of a volcano. So Madame Pele had to be appeased.
[0] https://en.wikipedia.org/wiki/United_States_Space_Surveillan...
The only problem Witness so much satelite in low orbit si tracking them during their life which us easy for thoses as they require precise tracking for being operational.