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A comment on Decluttering low-Earth orbit: It's time to tidy up space. Parent comment

Re:Decluttering low-Earth orbit: It's time to tidy up space by sandworm101 on Monday January 18, 2021 @10:36AM (#25822729)
The surface area of the sphere at 1400km is far greater than the earth's surface area. And satellites at that altitude are traveling much slower. Put together, the probabilities would akin to a handful of birds flying on earth, at random altitudes/places/directions, and two of them colliding.
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Re:Decluttering low-Earth orbit: It's time to tidy up space by CodesInChaos on Tuesday January 19, 2021 @07:22AM (#25832766)
> The surface area of the sphere at 1400km is far greater than the earth's surface area

It's only about 50% larger (1+1400/6371)^2 = 1.49

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Re:Decluttering low-Earth orbit: It's time to tidy up space by dr_dshiv on Monday January 18, 2021 @02:24PM (#25825457)
This! How likely would collisions be on a sphere the size of the earth? How do the probabilities change from low earth orbit to higher orbits?
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Re:Decluttering low-Earth orbit: It's time to tidy up space by bagels on Monday January 18, 2021 @12:22PM (#25824051)
"much slower" is still >7000 m/s
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Re:Decluttering low-Earth orbit: It's time to tidy up space by sandworm101 on Monday January 18, 2021 @12:42PM (#25824288)
Yes but at that altitude their orbital period is about 1/2 that of low orbits, meaning that even if two orbits do cross paths, there would be fewer potential collisions in a given time. They are 'slower' in relation to size of the sphere they occupy.
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Re:Decluttering low-Earth orbit: It's time to tidy up space by bagels on Monday January 18, 2021 @03:55PM (#25826524)
90 mins at 400km vs 110 mins at 1400km
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Re:Decluttering low-Earth orbit: It's time to tidy up space by jbrot on Tuesday January 19, 2021 @12:49AM (#25830434)
I guess that makes sense since the Earth’s radius is around 6400km so from 400 to 1400km is really a change from 6800 to 7800km which is proportionally similar to a change from 90 to 110 minutes.

Edit: I just looked up the formula for orbital period and it turns out period is proportional to radius^(3/2) (See: https://en.m.wikipedia.org/wiki/Orbital_period)

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