# Potential crash in orbit

**URL:** <https://boards.straightdope.com/t/potential-crash-in-orbit/923024>\
**Category:** Miscellaneous and Personal Stuff I Must Share\
**Created:** [October 15, 2020, 5:51pm UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024 "2020-10-15T17:51:18Z")\
**Posts on this page:** 7\
**Page:** 2

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**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\
**Post date:** [October 16, 2020, 1:56pm UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/21 "2020-10-16T13:56:48Z")

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Interestingly, NORAD is trying hard to get out of the (public) space tracking business and turn the (public) collision prediction & avoidance problem over to private data providers.

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**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\
**Post date:** [October 17, 2020, 7:28am UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/22 "2020-10-17T07:28:45Z")

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> [@LSLGuy](#):
>
> The Kessler-esque consequences for a polar-oriented collision are extra severe. The debris will amount to more of a “doomsday shroud” as encountered by the vastly more numerous equatorial satellites cross-cutting the debris cloud on every orbit.

Well, GPS was a good idea while it lasted. Hope all our earth-bound VOR stations are still working.

If they are in polar orbits, does that imply they are on a near-head-on collision course every time around? Sooner or later they are going to smack.

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**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\
**Post date:** [October 17, 2020, 9:24am UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/23 "2020-10-17T09:24:51Z")

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GPS satellites are not in low Earth orbit. On the other hand those 10000s of satellites providing Internet and similar services are…

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**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\
**Post date:** [October 17, 2020, 10:20am UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/24 "2020-10-17T10:20:26Z")

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> [@Senegoid](#):
>
> If they are in polar orbits, does that imply they are on a near-head-on collision course every time around? Sooner or later they are going to smack.

There’s always a chance. Of course, the two satellites have to be at the the same spot at the same point in time. If two satellites are at different altitudes, they’ll never collide. But these two had overlapping altitude ranges.

Spent upper stages seem to be a significant problem. They’re big, they’re uncontrolled, and they’re likely in a not particularly nice orbit. Responsible launch providers generally try to deorbit their stages, or at least put them in an orbit which will eventually lead to deorbit. But not all launch providers are equally enthusiastic about keeping space clean.

The only real consolation here is that orbits \<~500 km will naturally decay due to drag. Even in some worst-case Kessler event, the space below that point will clean itself up in a few years. Above that could be dangerous for millennia, though, without active cleanup efforts.

SpaceX’s Starlink constellation supposedly has autonomous, active collision avoidance. I expect them to release reports on how often this kicks in. It’ll be interesting to see how this plays out. The Heavens Above site [has a nice 3D visualization](https://www.heavens-above.com/StarLink.aspx?lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT) of the current constellation. One cool thing you can see is that while most of the constellation is fairly spread out, there are some notable dense lines of satellites. They are launching so rapidly that the previous launches have not yet had time to spread out along the orbit and change their phase.

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<div class="post-metadata">

**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\
**Post date:** [October 17, 2020, 7:22pm UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/25 "2020-10-17T19:22:11Z")

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Well, at least maybe that “doomsday cloud” will protect us when the aliens come to conquer us (as seen in, e.g., Independence Day).

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**Author:** ![Gray\_Ghost](https://avatars.discourse-cdn.com/v4/letter/g/c0e974/32.png) [@Gray\_Ghost](https://boards.straightdope.com/u/Gray_Ghost)\
**Post date:** [October 17, 2020, 8:29pm UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/26 "2020-10-17T20:29:07Z")

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Time for the garbage crew from _[Planetes](https://en.m.wikipedia.org/wiki/Planetes)_.

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**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\
**Post date:** [October 17, 2020, 8:44pm UTC](https://boards.straightdope.com/t/potential-crash-in-orbit/923024/27 "2020-10-17T20:44:34Z")

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Shit, I think it’s time for a rewatch. I really enjoyed that series. And the orbital mechanics was pretty good for a TV show. Really good, in fact, considering the competition.

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