Comment by southernplaces7
1 day ago
This really isn't all that much if you pause to consider it. For example. Lets take the larger possible number of 7500 plus 2,300 plus the 4,550 satellites noted up to 2021. That's a total of just under 15,000 satellites. Most of those are fairly small objects, at the most about the size of a typical mini-van, with most being quite a bit smaller than that.
Now, all of this is spread over a three-dimensional topography that's much larger than the total surface area of the Earth, and because their orbits are, as mentioned, three-dimensionally occupying various altitudes, the size of the total topography they move through is enormously larger than just one single surface area in square kilometers of a single hypothetical sphere X km above the Earth's surface. In the least case, even if all existing orbital satellites were stationed at the lowest possible orbital altitude, that's still quite a bit bigger than the 509 600 000 square km of the Earth's total surface. (too lazy to calculate the specific increment in this moment)
Across all of that, just 15,000 objects that are individually smaller than your average family sedan.
For comparison, the island of Manhattan has approximately 116,000 buildings crammed into it. If you spread those more or less equi-distantly from each other across the whole of the Earth's surface, water or air, there'd still be a tremendous amount of empty space between them. That's nearly 10 times as many objects individually much larger than any human satellite, across a much smaller surface area than what's occupied by our orbital satellites.
(Yes, I know we also have a shit-load of other inert junk zipping around up there at tens of thousands of KM per hour, but even if that stuff, most of which is very tiny, were included, we're still talking about an enormous amount of empty space between objects)
To those downvoting a completely innocuous comment like this and my other replies below, which simply put forth a thought experiment for the sake of debate, without asserting anything at all controversial: Grow an adult brain, no? idiotic as the downvote feature is in general, one would at least assume that the self-professed "intellectually above-average" readers of a site like this would use it better than 12-year-old rage-lords on a 4chan thread.
But apart from all the other stuff you mention, you’re missing an important point: these things move. And unless all objects are synchronized (which they are not) they occupy a whole orbit, not only their actual volume. If two orbits intersect, the objects occupying those will eventually collide.
Therefore, they occupy much more volume.
Yes. This is the idea behind Kessler Syndrome - that the accumulation of clutter in Earth orbit could lead to an "ablation cascade" as more and more things collide and more and more debris is created from those collisions leading to Earth orbit becoming too hazardous to traverse.
"A 1 kg object impacting at 10 km/s, for example, is probably capable of catastrophically breaking up a 1,000 kg spacecraft if it strikes a high-density element in the spacecraft. In such a breakup, numerous fragments larger than 1 kg would be created." https://orbitaldebris.jsc.nasa.gov/library/a-technical-asses...
The dimensionality of usable orbits is much less than 3.
For example all the GEO satellites are positioned along a 1D line.
I believe I described it badly or you misunderstood me then. What I was referring to in my mention of three-dimensionality is that the area in which all of them orbit isn't a single flat plane over a sphere shape. It's actually several flat planes layered on top of each other, with an obviously ever greater surface area the higher you go. Thus you have LEO, MEO and GEO satellites all sharing orbital space but at different heights so to speak. I'm aware that any given satellite generally flies along a fixed altitude (though as far as I know their latitude along that altitude can shift enormously)
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What you say is important of course, and it's what makes me less than sure in my assessment. It was after all more of a mental exercise in appreciating just how vast an area of space this relatively tiny quantity of objects is spread across.
To give one further perspective example here: a single large bulk container ship can carry up to 8,500 car-sized units.
This means that even if every single one of the maybe 15,000 satellites in orbit were the size of a car (most of them are much smaller actually), all together, they'd fill no more than the storage spaces of two bulk container ships with lots of room to spare at that.
This, spread over a multi-layered area as vast as our orbital space, means that even with their constantly moving at incredible speeds, and all the junk out there scattered between the satellites themselves, there's an enormous amount of emptiness between it all mitigating against impacts being very likely or frequent at all.
After all, of the 8,070 or so Starlink satellites in orbit right now, there's little mention of more than a few having been knocked out by debris in orbit. It seems that solar storms are their much bigger worry and cause of mishaps.
As the saying goes, space is huge, sometimes more than our brains can easily comprehend. This applies even in the comparatively tiny orbital regions of it that we use daily.
The mental exercise is fine for realising that satellites don't look as big as pictures of satellites in graphics, it's just missing the point that if you don't want to hit a 20cm x 20cm x 20cm cube that moves at 17,500 mph and has slow and limited capability to adjust that movement you need to allow it quite a bit more space, and be able to predict its movement accurately relative to yours. Especially if any collision means thousands of pieces of shrapnel that continue to move at 17500mph for decades or more, whilst potentially being too small to track but large enough to do a lot of damage.
Trains take up a negligible fraction of the mileage of the lines they operate on and rarely cross other lines, but signalling is still critical.
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