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'burial' or 'graveyard' orbit..


Umlüx

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more than often, i am reading about boosting old satellites or test payloads into a safe graveyard orbit, away from the heavy traffic near earth orbit.

but.. why? why boost them out there? if i have the fuel to change the orbit, why not deorbit them, let them burn up? is it that much cheaper (fuel-wise) to boost them all the way out (and maybe litter future precious orbit space) than slowing them down into the atmosphere?

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more than often, i am reading about boosting old satellites or test payloads into a safe graveyard orbit, away from the heavy traffic near earth orbit.

but.. why? why boost them out there? if i have the fuel to change the orbit, why not deorbit them, let them burn up? is it that much cheaper (fuel-wise) to boost them all the way out (and maybe litter future precious orbit space) than slowing them down into the atmosphere?

Because a lot of these graveyard satellites have nuclear reactors in them, would you like that to enter the atmosphere?

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more than often, i am reading about boosting old satellites or test payloads into a safe graveyard orbit, away from the heavy traffic near earth orbit.

but.. why? why boost them out there? if i have the fuel to change the orbit, why not deorbit them, let them burn up? is it that much cheaper (fuel-wise) to boost them all the way out (and maybe litter future precious orbit space) than slowing them down into the atmosphere?

Graveyard orbits are typically for GEO communication satellites, which constitute the vast majority of the birds up there. GEO is a circular orbit 35,786 km above the equator. At that altitude, it only takes a tiny amount of dV to push the satellite out to a graveyard orbit which is usually 300 km higher, where they will stay basically forever.

By comparison, to deorbit these sats, ie. to bring them down from 36000km to the ground, it would take the same amount of dV that it took to put them from LEO to GEO in the first place, which is a job typically done by a specialized upper stage.

Graveyard orbits are specifically chosen above GEO so as to not interfere with current or future satellite operations, and there is plenty of space up there. Only the specific GEO and LEO altitudes are used for actual operations, so graveyard orbit space is not 'precious'.

(It has nothing to do with nuclear reactors. Very few satellites have radioactive material on them)

Edited by Nibb31
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Graveyard orbits are typically for GEO communication satellites. These are typically on an equatorial orbit of 36000 km. At that altitude, it only takes a tiny amount of dV to push the satellite out to a graveyrd orbit of 37000 km.

To deorbit these sats, ie. to bring them down from 36000km to the ground, it would take the same amount of dV that it took to put them into GEO in the first place, which is a job typically done by a specialized upper stage.

Not quite. You just need to lower the perigee into the atmosphere. You don't need to fight gravity/drag and it takes much less dV. The problem is - many satellites are not very environmentally friendly (poisonous fuel/radioactive elements, etc). And yes, burning higher might still be the only option in terms of dV if not much fuel is left.

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Not quite. You just need to lower the perigee into the atmosphere. You don't need to fight gravity/drag and it takes much less dV. The problem is - many satellites are not very environmentally friendly (poisonous fuel/radioactive elements, etc). And yes, burning higher might still be the only option in terms of dV if not much fuel is left.

The dV cost of going to graveyard orbit is less than 10 m/s. Just dipping the periapsis under 100km alone would have taken a few km/s.

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Not quite. You just need to lower the perigee into the atmosphere. You don't need to fight gravity/drag and it takes much less dV. The problem is - many satellites are not very environmentally friendly (poisonous fuel/radioactive elements, etc). And yes, burning higher might still be the only option in terms of dV if not much fuel is left.

He means putting sat into GEO from GTO.

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The dV cost of going to graveyard orbit is less than 10 m/s. Just dipping the periapsis under 100km alone would have taken a few km/s.

This is basically correct. It takes 50m/s a year to maintain a GSO. That means you'll spend a couple months' worth of fuel getting it to graveyard orbit. However, it takes (1500m/s)/(50m/s)=30 years' worth of fuel to deorbit it. I imagine it's possible to reduce that using a gravity assist from the Moon (I could be horribly wrong, though), but it's more sensible to just throw it 300k higher and call it a day.

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No one cares about poisonous fuels on satellites, the reentry plasma will just rip them to elements anyway. If its nuclear, then if it reenters, there will be news everywhere. If its chemical, everything is still normal

It happened once in 1978.

People forgot about it by now, so I guess no one really care.

But for the OP, it does cost less dV to go to higher orbit than slow the satellite down. I am not a professional and I can't explain why was well as other people here, but that is my experience when I need to deploy my Remote Tech relays beacons (only core, energy system, antenna, thus can't put themselves to desired orbits). When I need to separate myself from the first satellite I deployed by 90 degrees, going up cost less dV than going down.

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It happened once in 1978.

People forgot about it by now, so I guess no one really care.

But for the OP, it does cost less dV to go to higher orbit than slow the satellite down. I am not a professional and I can't explain why was well as other people here, but that is my experience when I need to deploy my Remote Tech relays beacons (only core, energy system, antenna, thus can't put themselves to desired orbits). When I need to separate myself from the first satellite I deployed by 90 degrees, going up cost less dV than going down.

I believe what you have experienced is the Oberth Effect.

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The Dv to deorbit is about as much as the velocity difference of the two trajectories at that altitude. Or, the Dv to circularize from your transfer orbit. It's still much larger than what you would need for a graveyard orbit.

Something around 1.5 km/s...

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The main reason as pointed out earlier is the fuel costs, most GEO birds use their last drops of fuel to get into a graveyard orbits, some are even programmed to do it if they have lost contact with grounds stations for more than a certain period of time (measured in years)

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What the other posters said: Its ridiculously expensive to bring GEO satellites back to an earth intercept orbit from a dV perspective.

I did the math once, It's actually cheaper to crash a GEO sat into the moon(About 1.1km/s) than crashing them back down on earth (1.5km/s ish).

Better to just dump them in a graveyard orbit for 0.1km/s of dV. Space is big and the only thing going past GEO is the occasional scientific probe. It's a good solution.

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  • 2 weeks later...
so, we're rather messing up near earth orbit to save some bucks. nice.... :D

Though technically true, I think this remark overestimates how much or little you can actually send up with a given rocket. Different than in KSP, it actually takes a huge machine and massive amounts of money and effort to send something small up. Adding fuel or even engines to a craft to de-orbit it is hugely going to interfere with your efficiency. So yeah, technically it is about money, but in practice it is about making things feasible.

And yes, I too would prefer a clean SOI around Earth, but we really need cheaper launchers of some new type of technology for that.

Edited by Camacha
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thanks all.

so, we're rather messing up near earth orbit to save some bucks. nice.... :D

First, GEO is not "Near Earth Orbit". It's pretty far away, and the only practical use of GEO at the exact GEO altitude. The graveyard orbit that is above it is useless for any practical purpose.

Secondly, if you want a commercial space industry, then it's all about "saving bucks". If it wasn't economical to operate GEO sats, there would be no space industry at all and government launch prices would be prohibitive. If a GEO sat had to carry enough fuel to put itself and into GEO and to do a controlled deorbit from GEO, then it wouldn't spend enough time in operation, so it wouldn't be economical, and wouldn't exist in the first place.

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thanks all.

so, we're rather messing up near earth orbit to save some bucks. nice.... :D

Whats a mess today may be handy source of material tomorrow. Yes, it would need significant industrial capabilities but not having to haul every nut and bolt down from The Well could save incredible amount of money.

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thanks all.

so, we're rather messing up near earth orbit to save some bucks. nice.... :D

I think you're underestimating the savings. To de-orbit those satellites, they'd have to start burning while they still have 1.5km/s in the tanks. So, you're either launching heavier satellites to provide more dV reserve, or you're launching more of them to compensate for the reduced lifetime before the deorbit burn. Also, there may be significant cleanup costs for satellites which leave toxic or radioactive debris. Considering the number of satellites in GEO, the savings are likely in the billions.

Also, graveyard orbit will be relatively easy to clean, since everything in it is in more or less the same inclination.

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Whats a mess today may be handy source of material tomorrow. Yes, it would need significant industrial capabilities but not having to haul every nut and bolt down from The Well could save incredible amount of money.

Honestly, its not too much of a stretch to think of a small station up just outside of GEO, below the graveyard orbit though. Have some big magnets or some tethers that could be launched to catch the sats. Theyre not moving too much faster, 10s of m/s difference, and the mass of the cable itself, along with some light tension could slow them down and reel them in.

The station itself might need to stabilize its orbit a bit, but with some work and clever grabbing of sats at the right angles, it could probably stay in a pretty good spot.

Reel them in. Plenty of spare communications antennas/dishes, solar panels, various electronics, fuselages, little reaction motors, batteries. Yeah some stuff might be bad, but hey, the stuffs already up there, and its not exactly rusting like my old car.

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Because a lot of these graveyard satellites have nuclear reactors in them, would you like that to enter the atmosphere?

Along the lines of nuclear reactors entering the atmosphere, this was a problem that nasa had to tackle when bringing the crew of Apollo 13 home with the LEM in tow! It had a reactor onboard that was intended to have been left on the moon where, if it leaked, it could leak harmlessly.

- - - Updated - - -

Not quite. You just need to lower the perigee into the atmosphere. You don't need to fight gravity/drag and it takes much less dV. The problem is - many satellites are not very environmentally friendly (poisonous fuel/radioactive elements, etc). And yes, burning higher might still be the only option in terms of dV if not much fuel is left.

correct on the fuel end, because usually, the end of a satellites useful life, now that they use solar panels, is when they are nearly out of fuel to keep their orbits stable.

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Along the lines of nuclear reactors entering the atmosphere, this was a problem that nasa had to tackle when bringing the crew of Apollo 13 home with the LEM in tow! It had a reactor onboard that was intended to have been left on the moon where, if it leaked, it could leak harmlessly.

Not a reactor. It was a small RTG.

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