Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

space.com

Post reply on HN
Print view View original

11–20 of 105 posts

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#11

Post by goku12 »

aucisson_masque wrote: post #7

There are so many satellites in orbit that there is a pretty good chance that if even one was to be hit by something and explode in many pieces, it would crash another one and then another one until there is nothing left. The nasa is pretty scared of it, so is SpaceX.

That's the Kessler Syndrome. But it's better if it happens in a lower orbit, irrespective of what assets are present there. Space will be free for exploration again in a few years since all the debris there would eventually decay and deorbit.

The article mentions a few months at 480 km. I'm a little skeptical about this figure though, because the last tracked piece from an NRO satellite that was shot down at ~250 km by SM-3 missile in operation burnt frost, lasted 20 months in space before reentry. SpaceX is probably using a statistical cutoff percentage of fragments to calculate the time. But all the pieces are dangerous uncontrolled hypervelocity projectiles. Spain lost a military communications satellite a few days ago from a collision with a tiny undetermined space debris.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#12

Post by jdiez17 »

aucisson_masque wrote: post #9
Jean-Papoulos wrote: post #2

From a comment : >The first move in the coming WWIII, where the emperors try to expand their empires militaril,y will be to wipe out any orbit with Starlink satellites. I find this highly unlikely, given Starlink is soon to reached 10k satellites and will continue to grow. Why expand 10 000 ballistic missiles to bring down one of many communications networks ?

You don’t need 10k missiles. You need just one to blow up all of starlink satellites. This is like bowling, you hit one, it hits the other one etcétéras.

You would likely need at least one per orbital plane, of which there are about 24.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#13

Post by gpderetta »

lijok wrote: post #5
TOMDM wrote: post #4

Earlier quoted context omitted.

Because Kessler syndrome means you don't need to hit all 10k yourself. Lowering the orbits just means that we get back to normal faster, not that the it's impossible.

Does Kessler syndrome also mean ICBMs become nonviable?

I remember a short story about Canada preventing total global annihilation in WWIII, by deliberately triggering Kessler syndrome. My google-fu is failing me though.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#14

Post by [deleted] »

aucisson_masque wrote: post #7

There are so many satellites in orbit that there is a pretty good chance that if even one was to be hit by something and explode in many pieces, it would crash another one and then another one until there is nothing left. The nasa is pretty scared of it, so is SpaceX.

[deleted]

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#15

Post by iberator »

gpderetta wrote: post #13
lijok wrote: post #5

Earlier quoted context omitted.

Does Kessler syndrome also mean ICBMs become nonviable?

I remember a short story about Canada preventing total global annihilation in WWIII, by deliberately triggering Kessler syndrome. My google-fu is failing me though.

I would love to read it:)

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#16

Post by LightBug1 »

Jean-Papoulos wrote: post #2

From a comment : >The first move in the coming WWIII, where the emperors try to expand their empires militaril,y will be to wipe out any orbit with Starlink satellites. I find this highly unlikely, given Starlink is soon to reached 10k satellites and will continue to grow. Why expand 10 000 ballistic missiles to bring down one of many communications networks ?

What was that game on old PC's? ... Minesweeper ...

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#17

Post by wongarsu »

aucisson_masque wrote: post #7

There are so many satellites in orbit that there is a pretty good chance that if even one was to be hit by something and explode in many pieces, it would crash another one and then another one until there is nothing left. The nasa is pretty scared of it, so is SpaceX.

There are tentative signs that this is happening right now. As in: each collision causes debris that on average causes more than one additional collision, causing collision rates to go up exponentially.

But so far it's not anything like in Hollywood movies, it's just a graph slowly going up. There are about 12000 satellites orbiting earth. That looks like a lot on a map, but 12000 objects spread over an area larger than the surface of the earth isn't all that much

Like all exponential processes it will become a major issue if we don't address it, but this is one that starts pretty slow and is well monitored

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#18

Post by _factor »

goku12 wrote: post #11
aucisson_masque wrote: post #7

There are so many satellites in orbit that there is a pretty good chance that if even one was to be hit by something and explode in many pieces, it would crash another one and then another one until there is nothing left. The nasa is pretty scared of it, so is SpaceX.

That's the Kessler Syndrome. But it's better if it happens in a lower orbit, irrespective of what assets are present there. Space will be free for exploration again in a few years since all the debris there would eventually decay and deorbit. The article mentions a few months at 480 km. I'm a little skeptical about this figure though, because the last tracked piece from an NRO satellite that was shot down at ~250 km…

Two objects colliding can send debris into different orbits. Combined kinetic energy and mass differences can send debris to many different orbits.

A golf ball hitting a bowling ball or basketball, both traveling at 30 units of speed can produce quite a fast golf ball. Not all of the debris will safely burn up.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#19

Post by tlb »

Jean-Papoulos wrote: post #2

From a comment : >The first move in the coming WWIII, where the emperors try to expand their empires militaril,y will be to wipe out any orbit with Starlink satellites. I find this highly unlikely, given Starlink is soon to reached 10k satellites and will continue to grow. Why expand 10 000 ballistic missiles to bring down one of many communications networks ?

You could launch some missiles, blow a few satellites into smithereens, and gradually over the next few months they would take out the others. That's a poor kind of war weapon. An effective weapon is one where you can inflict damage continuously, and are able to stop immediately upon some concession. If you can't offer to stop in return for concessions, you won't get any.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#20

Post by choeger »

I think it's important to note that not all collisions are equally dangerous. Consider a sat on a polar orbit colliding with one on a equatorial orbit. Or two satellites on different directions. That is going to be spectacular. Otoh, these kind of collisions are unlikely and should be manageable by just assigning certain shells (say 5km) for every possible direction and orientation.

If two Starlink satellites collide that go roughly in the same direction, it's not exactly a huge problem.

I think the biggest issue is to coordinate this and potentially disallow some excentric orbits.

Post reply on HN