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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 whe

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?

anchpop 6y ago
No, it takes a lot of energy to get out of orbit. But unless the satellite is in a few very special locations in Earth's orbit, its orbit will naturally decay over time and eventually fall back to Earth, usually burning up in the atmosphere. (Above low-earth orbit this could take a very long time, but now satellites are required to be designed with deorbiting in mind) 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.
- throwaway-8c93 6y ago
  > No, it takes a lot of energy to get out of orbit 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?
  - cyphar 6y ago
    They were talking about escaping orbit (reaching escape velocity which is ~41% higher than the orbital velocity and requires getting more fuel into orbit), not degrading the orbit so that the satellite burns up in the atmosphere. As the article discusses, the latter has the flaw of putting alumina particles in the upper atmosphere which remain there for many years.
  - jvzr 6y ago
    I'm pretty sure parent meant "escape Earth's orbit", not "deorbit"
- Symmetry 6y ago
  Orbital decay depends on a satellite's particular orbital height to a huge extent. A satellite orbiting 250 km up might come down in a week. The same one at 500 km might take centuries.
wintorez 6y ago
Moving off the orbit is not as easy. You basically have to slow down in order to de-orbit, and that requires rockets. These end of life rockets adds to the weight of each satellite which adds to the cost of launching them.
- buran77 6y ago
  The problem that wooden satellites would address is space junk falling to Earth and aluminum burning up on reentry, leaving particles in the atmosphere: > 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
  - ratsforhorses2 6y ago
    What about little drones that pushed them out of orbit?
    - ratsforhorses 6y ago
      https://www.hindawi.com/journals/jchem/2019/4753910/ https://www.hindawi.com/journals/jchem/2019/4753910/
- Rebelgecko 6y ago
  There's some interesting work that's been done with using electromagnetic tethers to deorbit
  - vagrantJin 6y ago
    This is interesting. Cant we automate this and have drones tether the debris? It could launch from the ISS by mechnical propulsion (throw that bad boy with a mechanical arm)
    - Rebelgecko 6y ago
      The ones I've seen are mostly intended to be installed on cubesats as a primary or backup method of deorbiting. However if it works well I suppose they could also be put onto little probes that latch onto problematic debris. Dunno if that's cost effective
andreareina 6y ago
Assuming you don't mean to literally blow up the satellite, unless you have enough fuel to boost the satellite to earth escape velocity (expensive), it's not going to "spiral away" but get boosted to an elliptical orbit where the highest point ("apogee") is going to be at a higher altitude, but the lowest point ("perigee") is still going to be the same low altitude it started from. You could do a second burn at apogee to circularize the orbit and thus keep the satellite at that altitude all the time, but that's more fuel again. 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.
- kolinko 6y ago
  +1 - delta v is what matters, and a regular explosive would not throw a satellite off orbit significantly. 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...
  - wongarsu 6y ago
    No matter how you explode it, turning one piece of debris into many pieces at even higher velocities is only making things worse.
    - KMag 6y ago
      To add to this, given what we're learn about nuclear weapons in school/media, you'd think a small fission device would convert the entire mass of the satellite into a ball of mixed plasma and vapour. A lot of the non-metallic mass of the satellite would probably vaporize, but any surviving bits would have a bunch of added kinetic energy. 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. [0] https://www.youtube.com/watch?v=by1xpy8ob8E https://www.youtube.com/watch?v=by1xpy8ob8E
Fordec 6y ago
Graveyard orbits for GEO, and forced atmospheric drag for LEO. 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.
- m4rtink 6y ago
  The space debris section will have to pick it up manually: https://en.m.wikipedia.org/wiki/Planetes https://en.m.wikipedia.org/wiki/Planetes
  - Fordec 6y ago
    One of my top three favorite shows ever. Still the standard I hold hard sci-fi to for doing the space environment right. Even if it's a bit dated on it's Japanese work place love interest plot.
dwightgunning 6y ago
Even if it were feasible... it seems like it would just defer the problem to a later time or place the burden on other intergalactic citizens.
- adrianN 6y ago
  Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
saargrin 6y ago
it would be easier to have it spiral into the atmosphere and burn up i mean thats what happens to most satellites anyway
MaulingMonkey 6y ago
Escaping earth's orbit is expensive. Much cheaper in mass/payload/$$$ to simply deorbit and burn up for a lot of low earth orbit satellites. Or even "free" - a lot of these satellite megaconstellations will be brought down by atmospheric drag within a year of running out of fuel: https://en.wikipedia.org/wiki/Graveyard_orbit#Disposal_orbit 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.
geocrasher 6y ago
As usual, Scott Manley has an excellent video that discusses spacey things. This one is about Graveyard Orbits: https://www.youtube.com/watch?v=ruf_mfjOt9k https://www.youtube.com/watch?v=ruf_mfjOt9k

anchpop 6y ago

No, it takes a lot of energy to get out of orbit. But unless the satellite is in a few very special locations in Earth's orbit, its orbit will naturally decay over time and eventually fall back to Earth, usually burning up in the atmosphere. (Above low-earth orbit this could take a very long time, but now satellites are required to be designed with deorbiting in mind) 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.

throwaway-8c93 6y ago
> No, it takes a lot of energy to get out of orbit 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?
- cyphar 6y ago
  They were talking about escaping orbit (reaching escape velocity which is ~41% higher than the orbital velocity and requires getting more fuel into orbit), not degrading the orbit so that the satellite burns up in the atmosphere. As the article discusses, the latter has the flaw of putting alumina particles in the upper atmosphere which remain there for many years.
- jvzr 6y ago
  I'm pretty sure parent meant "escape Earth's orbit", not "deorbit"
Symmetry 6y ago
Orbital decay depends on a satellite's particular orbital height to a huge extent. A satellite orbiting 250 km up might come down in a week. The same one at 500 km might take centuries.

wintorez 6y ago

Moving off the orbit is not as easy. You basically have to slow down in order to de-orbit, and that requires rockets. These end of life rockets adds to the weight of each satellite which adds to the cost of launching them.

buran77 6y ago
The problem that wooden satellites would address is space junk falling to Earth and aluminum burning up on reentry, leaving particles in the atmosphere: > 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
- ratsforhorses2 6y ago
  What about little drones that pushed them out of orbit?
  - ratsforhorses 6y ago
    https://www.hindawi.com/journals/jchem/2019/4753910/ https://www.hindawi.com/journals/jchem/2019/4753910/
Rebelgecko 6y ago
There's some interesting work that's been done with using electromagnetic tethers to deorbit
- vagrantJin 6y ago
  This is interesting. Cant we automate this and have drones tether the debris? It could launch from the ISS by mechnical propulsion (throw that bad boy with a mechanical arm)
  - Rebelgecko 6y ago
    The ones I've seen are mostly intended to be installed on cubesats as a primary or backup method of deorbiting. However if it works well I suppose they could also be put onto little probes that latch onto problematic debris. Dunno if that's cost effective

andreareina 6y ago

Assuming you don't mean to literally blow up the satellite, unless you have enough fuel to boost the satellite to earth escape velocity (expensive), it's not going to "spiral away" but get boosted to an elliptical orbit where the highest point ("apogee") is going to be at a higher altitude, but the lowest point ("perigee") is still going to be the same low altitude it started from. You could do a second burn at apogee to circularize the orbit and thus keep the satellite at that altitude all the time, but that's more fuel again. 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.

kolinko 6y ago
+1 - delta v is what matters, and a regular explosive would not throw a satellite off orbit significantly. 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...
- wongarsu 6y ago
  No matter how you explode it, turning one piece of debris into many pieces at even higher velocities is only making things worse.
  - KMag 6y ago
    To add to this, given what we're learn about nuclear weapons in school/media, you'd think a small fission device would convert the entire mass of the satellite into a ball of mixed plasma and vapour. A lot of the non-metallic mass of the satellite would probably vaporize, but any surviving bits would have a bunch of added kinetic energy. 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. [0] https://www.youtube.com/watch?v=by1xpy8ob8E https://www.youtube.com/watch?v=by1xpy8ob8E

Fordec 6y ago

Graveyard orbits for GEO, and forced atmospheric drag for LEO. 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.

m4rtink 6y ago
The space debris section will have to pick it up manually: https://en.m.wikipedia.org/wiki/Planetes https://en.m.wikipedia.org/wiki/Planetes
- Fordec 6y ago
  One of my top three favorite shows ever. Still the standard I hold hard sci-fi to for doing the space environment right. Even if it's a bit dated on it's Japanese work place love interest plot.

dwightgunning 6y ago

Even if it were feasible... it seems like it would just defer the problem to a later time or place the burden on other intergalactic citizens.

adrianN 6y ago
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

saargrin 6y ago

it would be easier to have it spiral into the atmosphere and burn up i mean thats what happens to most satellites anyway

MaulingMonkey 6y ago

Escaping earth's orbit is expensive. Much cheaper in mass/payload/$$$ to simply deorbit and burn up for a lot of low earth orbit satellites. Or even "free" - a lot of these satellite megaconstellations will be brought down by atmospheric drag within a year of running out of fuel: https://en.wikipedia.org/wiki/Graveyard_orbit#Disposal_orbit 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.

geocrasher 6y ago

As usual, Scott Manley has an excellent video that discusses spacey things. This one is about Graveyard Orbits: https://www.youtube.com/watch?v=ruf_mfjOt9k https://www.youtube.com/watch?v=ruf_mfjOt9k