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!
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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.
Wont you eventually leave orbit if you are too far away?
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.
If you go above a certain speed (escape velocity) you will indeed leave, but you’ll leave right away, not eventually.
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.
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.
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 🙂
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 :)
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.
That spring is also a good visual to help illustrate what is meant by “gravity well”.
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.
Name checks out :D
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
Most modern GEO sats actually have dedicated end-of-life fuel reserves specifically to boost themselves into that “graveyard orbit” about 300km higher than GEO, where they’ll stay for basically eternity without interfering with active satellites.
Adding to other’s responses, exploding thing at geostationary orbit is especially bad:
- there is roughly only one such orbit
- 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)
- 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
- 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
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.
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 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.
