33
submitted 1 day ago by [email protected] to c/[email protected]

Maybe this should be in Nostupidquestions as I'm aware the moon exists. And I guess there may be an orbit zone where things tend to remain in orbit. But curious...

The full context question is: For man-made satellites, would they benefit by having a "Self destruct" button?

Sure it may add more debris but since an explosion would scatter debris in all directions, anything flung up or down would cause it to get out of this geostationary zone/band.. And hopefully come crashing down to Earth, reducing overall debris? Compared to an abandoned satellite, remaining in orbit and breaking down due to relatively low energy collisions with surrounding debris.

Basically I'm trying to justify self destruct buttons. Thank you!

top 29 comments
sorted by: hot top new old
[-] [email protected] 7 points 1 day ago

Adding to other's responses, exploding thing at geostationary orbit is especially bad:

  1. there is roughly only one such orbit
  2. because of (a) it is much more limited in terms of amount of spots for satellites distant enough from each other to be considered safe (imagine beads)
  3. because of orbital mechanics destroying things creates cloud of debris that eventually takes up form roughly similar to torus, embedding original orbit, endangering all other satellites here and threatening to start chain reaction of creating more and more debris from collisions
  4. this orbit is quite high and atmosphere here is so miniscule it'd take hundreds and thousands of years for that debris to meaningfully slow down and drop to lower trajectories; and junk that got higher orbits will decay even slower. It's not coincidence that graveyard orbit for geostationary satellites is higher

All in all, don't explode things here

[-] [email protected] 32 points 1 day ago

All orbits require very minimal maintenance, the closer to earth, the more maintenance required . Far enough out, and its basically maintence free, except for avoiding other debris.

The problem with an explosive self destruct is that not all debris will go down into lower orbits, some with go higher and therefore take even longer to deorbit. Its also a lot easier to track one dead satellite instead of thousands of minute particles.

And ideal "self-destruct button" would actually be a thruster firing in the direction of travel, which would slow it down and drag it into the earth, or if facing the other way, boost it up to a "graveyard" orbit. Both these exist on many satellites already.

[-] [email protected] 12 points 1 day ago* (last edited 1 day ago)

As an addendum to this comment:
The moon is also a source of orbital pull and does affect everything on the inside of its orbit and is probably the most significant source of disturbance at geostationary distances.

[-] [email protected] 5 points 1 day ago

And ideal “self-destruct button” would actually be a thruster firing in the direction of travel, which would slow it down and drag it into the earth, or if facing the other way, boost it up to a “graveyard” orbit. Both these exist on many satellites already.

Also, even if they don't, it'd be possible to send another spacecraft up that has enough fuel to deorbit the satellite.

[-] [email protected] 2 points 1 day ago* (last edited 1 day ago)

Theoretically, anyway. It's still experimental to do so, and the fact stuff is quite often spinning makes it harder.

IIRC using laser ablation is also a legit technique in consideration to give old space junk a push.

[-] [email protected] 2 points 1 day ago

Wont you eventually leave orbit if you are too far away?

[-] [email protected] 1 points 17 hours ago

If you go above a certain speed (escape velocity) you will indeed leave, but you'll leave right away, not eventually.

[-] [email protected] 4 points 1 day ago

Depends. Do you mean around a conceptual single body in an infinite void, or are there other things out there?

The (circular) orbits in a gravitational well don't end, they just get slower and slower as you move outwards forever. But, in real life you'll be in a zone where other things have just as much pull after a while, and then anything could happen.

[-] [email protected] 2 points 1 day ago

Yes, but I beleive that is quite a significant amount of energy to reach. Only a few spacecraft have left earths orbit. Fewer still have left the suns orbit.

[-] [email protected] 1 points 1 day ago* (last edited 1 day ago)

Thank you for your response!

Pardon my crappy drawing and simplification.. trying to understand..

  • So Zone 1 requires a lot of maintenance energy
  • Zone 2 may be maintenance free zone
  • Zone 3 may require more energy than Zone 2 but less than Zone 1
  • And finally Zone 4 will be even less energy to stay in orbit but needs more energy to stay in line due to increased travel distance

Is that right?

But yes, there goes my self destruct notion down the drain.

[-] [email protected] 5 points 1 day ago* (last edited 1 day ago)

There is no orbit altitude that requires more energy to maintain than a lower altitude.

Zone 1 requires more reboosting that 2, which requires more than 3, which requires more than 4. I dont know the exact relationship, (someone else might know), but we can consider it linear for simplification. The further away from earth, there will be less atmospheric drag, which means a longer stable orbit.

The travel distance doesn't really change anything, it doesn't affect the orbit stability.

Think of it like this spring. Your satellite can start at any point, and with no additional energy, Itll follow the path all the way down to the middle (earth). Start low, and itll reach ground quickly, start high, and itll take a lot longer. There is no energy required to stay on the spiral path. Once the sat is low enough, you may want to reboost, which is when you need to use energy to jump up to a higher point on the spiral, at which the path continues.

[-] [email protected] 3 points 1 day ago

That image and your description helped a ton. So there isn't a magic zone but more of a threshold after which things get easier to maintain.

Really should start playing Kerbal Space Program as someone before pointed out. You seem to have a great conceptual model of this. Thank you for engaging 🙂

[-] [email protected] 1 points 8 hours ago

Outer Wilds is much more user friendly imo. Also the fact that some planets/comets are so small you can basically run and jump at orbital speeds really helps you to conceptualize the interaction of forces.

I spent a whole cycle jumping from north pole to south pole with just my jetpack on this neat binary planet system. The gravity on them is so low you can jump off one planet, boost straight up, and fall all the way to the other planet without your ship. It's really fun.

[-] [email protected] 4 points 1 day ago

Not even a threshold, its a much more smooth transition, thats just the best picture I could find.

KSP will definitely help. Chuck your SATs into orbit, and you can see the orbits slowly decay away, almost imperceptibly. Its fun too :)

[-] [email protected] 12 points 1 day ago

Sorry to disappoint, but exploding something at GEO would make things worse.

All satellites in orbit of Earth will experience atmospheric drag. Even the Moon is bumping into gas atoms.

Geostationary satellites will eventually fall. It might take millions of years, but eventually the thin atmosphere will slow those satellites down enough that their orbit will fall into the thick, lower atmosphere where they'll burn up or crash into the Earth's surface.

Exploding a satellite up there will just make a shotgun spray of projectiles that will still take millions of years to fall. Assuming the projectiles shoot off in all directions fairly evenly, then the ones that get shot backwards relative to the motion of the satellite will end up in a lower orbit that will decay faster. The pieces that get shot forward might actually escape Earth orbit all together and become little asteroids orbiting the Sun.

The thing that's special about geostationary orbit isn't that the orbit of things at that altitude does not decay. That altitude is special because at that altitude, orbital speed is equal to the Earth's rotational speed. A satellite at that altitude over the equator will remain over that same longitude - it won't rise and set like the Moon, it will remain in the same spot overhead both night and day.

[-] [email protected] 8 points 1 day ago

Name checks out :D

[-] [email protected] 1 points 1 day ago

Hmm, it looks like you need a bit over a kilometer per second to escape Earth from GEO. I guess that's not impossible with high explosives. I don't think any shrapnel would make it back to earth, though, since they'd have to lose most of the 3 km/s

[-] [email protected] 2 points 1 day ago

Losing ~1.4 km/s at GEO would put a fragment into geostationary transfer orbit, with one side of the elliptical orbit at geostationary altitude and the other side at low orbit altitude where it would experience increased drag.

[-] [email protected] 3 points 19 hours ago* (last edited 19 hours ago)

Ah, okay. So not quite most then. My bad; orbital mechanics takes some getting used to even at this elementary level.

Also, I just noticed, relevant username.

[-] [email protected] 3 points 1 day ago

Cheers for the detailed response! Seems I'll have to scratch the destruct button from my imaginary space station and replace with a simple thruster.

Didn't realise particles shooting away from Earth wouldn't realistically come down again. I'll have to read up more on Orbital mechanics

[-] [email protected] 9 points 1 day ago* (last edited 1 day ago)
[-] [email protected] 2 points 1 day ago

This is so dumb it's almost brilliant. If you go to a job, you're working class. If you make rules, you're the ruling class.

[-] [email protected] 7 points 1 day ago* (last edited 1 day ago)

Nope. Orbits are defined as being passive and repeating trajectories.

They're also the default way things move in gravitational well, unless there's a collision or thrust. To be clear, geostationary orbits are way further out than the standard low-Earth orbits, like multiple Earth widths away. So, deorbiting a satellite from there requires a very sustained rocket boost, and if you just blow it up you'll get a slightly wider debris field of junk in random orbits and very little if anything re-entering.

It's a bit of an interesting aside that how easy orbits are to find is important for there being planets in the first place, or even galaxies. A collapsing cloud of dust and gas would end in a lone star or black hole every time, if some of the infalling matter didn't get "stuck".

When possible, deorbiting for safety is a standard thing, though. At least now that we worry about too much space junk; the Apollo engineers weren't thinking about it yet. It's always done by thrusting into the atmosphere.

Edit: And for geosynchronous satellites, they actually just move into a slightly higher graveyard orbit so they're at least out of the way.

[-] [email protected] 3 points 1 day ago

Appreciate your response!

It clicked when you mentioned "multiple Earth widths" which made me realise how large space is and why my assumption of blasting debris out of orbit is so insane.

And your aside is now even more amazing given the vastness and the eons of time required to make it all function without it collapsing into a big hole. It's one thing to be slightly aware of space shenanigans and another to actually ponder.

I'm glad there are such safety standards.. just learnt of the Kessler Syndrome down below and it's a scary thought of humanity creating it's own prison

Thanks.

[-] [email protected] 4 points 1 day ago

No problem! I should maybe point out that the moon is several times further yet, since you mentioned it. And that pretty much only communication satellites use GEO.

Here's a site where you can experience the solar system to scale, if you want to get it once and for all. It does take a while to get through. Interstellar distances are so much bigger there would be no point - it's basically just beyond direct comprehension.

[-] [email protected] 4 points 1 day ago

The amount of space between planets is crazy. My old school had a scale model of the solar system using the same scale for size and distance.

On one end of campus there was a 12" yellow sun. Around campus were poles with little domes on top that had little pins with plant models suck in them.

[-] [email protected] 2 points 10 hours ago* (last edited 10 hours ago)

Hmm, looks like there's actually several of these at universities. I have heard about them.

Wikipedia has a list. There's even more than one that incorporates Alpha Centauri, although one cheats by using a full trip around the Earth (the other one is in Finland and places Proxima in Australia).

[-] [email protected] 5 points 1 day ago

Maintaining geosynchronous orbit does require maintenance because there's still a non-trivial amount of air resistance that will slowly decrease speed and de-orbit the satellite.

With a bit more detail: there is a specific altitude and speed that an object must maintain in order to stay in orbit above a fixed point above the earth. Earth's mass, and thus its gravitational pull, dictate this speed and altitude through physics. There are other speeds and attitudes that can achieve the same effect (geosynchronous orbit) but they require propulsion to maintain. With the Earth, that "sweet spot" where you can achieve the correct orbital velocity to keep a geosynchronous orbit is still within the atmosphere, albeit very thin, so friction with the air slowly makes satellites lose speed. An orbit is based on speed (speed up and you get farther away from the planet, slow down and you draw closer to the planet) so as the satellites slow down they have to periodically "boost up" or eventually their orbit will decay and they'll re-enter and burn up.

Self destruct? Not a good idea. Controlled re-entry is essentially self destruct.

More space junk from just a random explosion is really bad. Space junk is really bad. If it gets bad enough it can potentially have a cascading effect where space junk collides with other stuff and causes more space junk and explosions, starting a chain reaction that creates a scatter field of junk that traps us on the planet. The concept is known as Kessler Syndrome.

https://en.m.wikipedia.org/wiki/Kessler_syndrome

[-] [email protected] 2 points 1 day ago

Thank you so much for the detailed response. That Kessler syndrome is scary..

So the best method is a controlled reentry. From the wikipedia link, I'm now inspired to replace the self destruct button to a megawatt laser for dealing with debris.

this post was submitted on 08 Jun 2025
33 points (94.6% liked)

Ask Science

11125 readers
51 users here now

Ask a science question, get a science answer.


Community Rules


Rule 1: Be respectful and inclusive.Treat others with respect, and maintain a positive atmosphere.


Rule 2: No harassment, hate speech, bigotry, or trolling.Avoid any form of harassment, hate speech, bigotry, or offensive behavior.


Rule 3: Engage in constructive discussions.Contribute to meaningful and constructive discussions that enhance scientific understanding.


Rule 4: No AI-generated answers.Strictly prohibit the use of AI-generated answers. Providing answers generated by AI systems is not allowed and may result in a ban.


Rule 5: Follow guidelines and moderators' instructions.Adhere to community guidelines and comply with instructions given by moderators.


Rule 6: Use appropriate language and tone.Communicate using suitable language and maintain a professional and respectful tone.


Rule 7: Report violations.Report any violations of the community rules to the moderators for appropriate action.


Rule 8: Foster a continuous learning environment.Encourage a continuous learning environment where members can share knowledge and engage in scientific discussions.


Rule 9: Source required for answers.Provide credible sources for answers. Failure to include a source may result in the removal of the answer to ensure information reliability.


By adhering to these rules, we create a welcoming and informative environment where science-related questions receive accurate and credible answers. Thank you for your cooperation in making the Ask Science community a valuable resource for scientific knowledge.

We retain the discretion to modify the rules as we deem necessary.


founded 2 years ago
MODERATORS