mithie007 t1_it5nr8n wrote on October 21, 2022 at 2:46 AM

Reply to comment by aecarol1 in China looked at putting a monitoring satellite in retrograde geostationary orbit via the moon by OkOrdinary5299

This... seems off. I'm not saying it won't work - but it's definitely not as trivial as just setting off a shrapnel bomb a bit above geosync orbit.

Orbital space isn't as crowded as it seems - it's quite high up and the amount actually occupied by satellites is infinitesmal.

Plus which, if you set off an explosion on top of the geosynch orbit, only a very minor fraction of the debris will remain in geosynch orbit. Most will be propelled to a higher or lower orbit. And the debris that do end up in geosynch orbit will have very low relative velocity to the other satellites, since they share the same orbit.

Plus, it's difficult to get a killshot on a satellite unless you're aiming for one. You can nick a solar panel or a make a hole in the casing, but to render the satellite inoperable, you'd have to punch through one of its vital systems - for example - the CPU, a comms antenna, or the battery array.

Which - especially on one of the larger milsats - makes up a small fraction of the total satellite mass.

This sounds like the kessler syndrome scare again.

aecarol1 t1_it5rddm wrote on October 21, 2022 at 3:15 AM

Most orbits don't have to be extremely precise. A satellite will pass overhead a few seconds earlier or later over time. They correct the drift when it gets bad enough, but it's not a deal breaker, moment to moment if it's early or late.

But the geostationary orbit does need to be fairly precise. There are millions of dishes that point to the location. The further it is from its exact slot, the more it will drift across the sky. That's undesirable, so they try to keep it right on the centerline of the orbit.

The bad guys would not so much "explode" the vehicle, as unzip it, releasing the millions of balls, letting orbital dynamics do the work. over a few hours they will spread out. Getting hit by one one at 14,000 mph could be awful.

Considering a small fleck of paint actually made a small divot in a Space Shuttle window, imagine what a ball bearing weighing 1/10th of an ounce will do at 14,000mph

You can fit about 3.5 million 1/8th inch ball bearings in 1,000 pounds. That's a lot of debris released all-at-once.

mithie007 t1_it5whvg wrote on October 21, 2022 at 3:59 AM

So my initial reaction is, you have satellites, which do station keeping, and ball bearings, which do not. So after the initial blast, the vast majority of the debris should be kicked to a different orbit, and no longer a "threat" to the current orbit.

That said, I'd imagine debris kicked off into the lower orbits could pose a serious concern to future satellite launches.

I agree that the initial impact will be quite devastating, but it won't disable the entire orbit.

Captain_Hadock t1_it6jjcj wrote on October 21, 2022 at 8:32 AM

The reason it doesn't sound destructive is because you missed the part where the debris are being released in a retrograde GEO-altitude orbit (which isn't harder to reach than regular GEO). Which means they would still follow a GEO-like orbital path, but going the opposite way (impact velocity will be 6 km/s or 13400 mph).

mithie007 t1_it6qu94 wrote on October 21, 2022 at 10:17 AM

Yup. Thank you. That's what I was missing

Yeah if you can get a bunch of ball bearings going retrograde, you will rip up the entire orbit like a shotgun blast that keeps on going.

aecarol1 t1_it5xp7e wrote on October 21, 2022 at 4:10 AM

No need for a real blast. Just unzip and release them. Orbital dynamics will spread them out. Combinations of sunlight, magnetic fields, jostling with each other will spread them out over a period of days.

They might do like SpaceX does with Starlink. Rotate the vehicle slowly and then just please the payload. A very slow spin will impart enough delta-V to cause them to slowly spread out.

Station keeping tries to keep these satellites within 0.15 degree of their slot. That's about 60 miles worst case. Releasing a few million ball bearings could be awful, especially since you get "another shot" at a collision with any specific satellite every 12 hours.

There have been two confirm hits by space debris on geostationary satellites already with another 20 suspected. That was because of accidents. Now imagine several tons of debris specifically put there for that exact purpose.