I don't know satellites at all, so bear with me if I'm being too naive.
Would it be feasible to put a self-destructive program in each satellite, such that when it retires, it moves off the orbit away from the earth, and spirals away?
Would it be feasible to put a self-destructive program in each satellite, such that when it retires, it moves off the orbit away from the earth, and spirals away?
https://en.wikipedia.org/wiki/Graveyard_orbit#Disposal_orbit
This also provides some passive decluttering of low earth orbit in case of hardware failures and the like.
Such self destruct programs (or manual commands from a ground station) are common for farther out orbits like geostationary, although they typically just enter a slightly different orbit where they're out of the way and not taking up valuable real estate in particularly useful orbits, instead of escaping earth's gravity or deorbiting completely.
Often some parts of the sat still make it to the ground, but SpaceX's Starlink sats for example are designed to fully burn up in-atmosphere within a year of deorbiting.
Does it? It takes ~10000 m/s of delta-v to reach low Earth orbit, but afaik only about extra ~30 m/s to deorbit, with aerobraking taking care of the rest of the velocity. Or is there any extra intricacy in the details?
Now, what happens if the propulsion is broken? Or out of fuel. Or the drag mechanism failed to deploy? How does any sophisticated deal with the physical reality of it not being able to move itself? Self retirement assumes the happy path that everything goes according to plan without breaking in a radiation rich environment moving at thousands of km per second.
IIRC per a video by Scott Manley they do this for geostationary satellites and maybe at medium orbits, but for low-earth orbits (the majority of satellites) the extra fuel requirement goes against the cost advantage of LEO.
But this makes me wonder - what is the minimum possible size for a nuke? I wonder if say 1-2kg nuke would be enough to throw all the debris out of orbit...
Especially for things that reflect both infrared and soft x-rays, with pretty high melting points and pretty high thermal masses, nuclear explosions do less damage than you'd think.
There was a nuclear test where they put a steel sphere about the size of a bowling ball pretty close to a device similar to Gadget / Fat Man. Spoiler alert: it survived barely scratched.[0]
You could probably design a satellite with thin enough pieces of metal and add carbon black / carbon fiber to any polymers too transparent to IR/soft x-rays. You could probably also use a thermonuclear device, but the particle steams caught in the earth's magnetic field would damage satellites, and there's also the EMP to worry about.
I don't get it. Can you blow something only in one direction?
[1] The smallest (publicly known) nuclear device ever built weighed about 23 kg.
[2] Detonating a nuke in orbit would cause a potentially devastating EMP.
[3] The Outer Space Treaty explicitly prohibits putting WMDs in space.
[1] https://en.wikipedia.org/wiki/W54
[2] https://en.wikipedia.org/wiki/High-altitude_nuclear_explosio...
> We are very concerned with the fact that all the satellites which re-enter the Earth's atmosphere burn and create tiny alumina particles which will float in the upper atmosphere for many years
Though speculatively I've read that making sure the optics burn up in deorbit is a major problem to adding inter satellite laser links.
[1] https://spectrum.ieee.org/tech-talk/aerospace/satellites/spa...
I'm curious about these absolute claims. Can a heavy mass object moving more slowly entangle a faster object to reduce velocity.
Can solar sails be used to reduce or change orbits?
Magnetic fields?
Physical characteristics and profile of sat vs orbit?
Put in a decaying orbit that is only maintained by a thrusters?
Very interesting to hear that the only way to slow something down is with rockets. Not atmo drag. No mag drag. No solar pressure etc.
"Can solar sails be used to reduce or change orbits?" Yes! It's a bit overkill, but yes that is something one can do.
"Magnetic fields?" There are very promising results in that direction too. A satellite can unfurl a long thin conductive tether. The magnetic field of the planet generates a current in the tether and a net drag on the sat.(To be 100% honest I don't understand this solution enough, but "Terminator Tether" is a term one can search for more info.)
"Physical characteristics and profile of sat vs orbit?" Maybe! On low orbits you can count on the very thin atmosphere to provide you some drag. It's a common practice for example with cube sats to not put them too high, so even if something goes wrong with their electronics they will deorbit on their own in a few months or years. You can also increase this drag by turning your sat to "face the wind" with the largest available cross-section. This trick doesn't really work on higher orbits though, and that's where "space junk" is generally a problem.
"Put in a decaying orbit that is only maintained by thrusters?" I'm not sure what you mean. Thrusters are rockets. But yes, that absolutely works. With the usual caveats. You have to budget enough fuel for the manoeuvre, and if your ageing sat craps out you might not be able to command it anymore.
i mean thats what happens to most satellites anyway