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What is the maximum mass of a satellite that can be placed in GEO? Or can satellites of any mass be placed in GEO?

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    $\begingroup$ Assuming on-orbit assembly, there is no hard limit. To know what can be launched at once, you have to specify the launcher model, launch site, upper stage and fairing diameter. $\endgroup$ – Deer Hunter Aug 19 '13 at 12:03
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    $\begingroup$ To see for yourself the mass to GTO, use elvperf.ksc.nasa.gov/elvMap $\endgroup$ – Deer Hunter Aug 19 '13 at 12:08
  • $\begingroup$ GEO satellite can have ion drives. So, for single launch, theoterically GEO sat mass can be as large as low earth orbit capacity minus several percent - for mass of xenon propellant. $\endgroup$ – Heopps May 24 at 5:38
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Assuming orbital assembly (with separate launch vehicles, each delivering a portion of the total mass of the satellite), there is no real upper limit, short of technical limitations that we're currently struggling with. At least not until you orbit such a huge mass, that you literally start playing the game of pool with celestial bodies, permanently destabilize their orbits, cause extinction level event and terminate any life on the Earth as we know it due to gravitational pull between two objects (the Earth and the satellite) so huge, they start "feeding" on each other's mass by forming an accretion disk connecting the two, and suffocate their own atmospheres with it (among a plethora of other undesirable side effects).

The GEO orbited mass could as well be larger than the total mass of the Earth, and we have Charon, locked in the skies of Pluto as a proof of that. Pluto and Charon are tidally locked in a synchronous orbit, meaning they always face each other with the same side (as do the Earth and our Moon), but also synchronously orbiting each other (Pluto orbits a point that is outside its body), meaning Charon is locked in the skies of Pluto as a rock that's been frozen in motion, and Pluto is locked in the skies of Charon. Charon has approximately 11.65% of the mass of Pluto, meaning Pluto has about 8.6 times the mass of Charon, yet it's still technically in a GEO orbit "around" it.

    enter image description here   enter image description here   enter image description here

     Cosmic dance, face to face: Two bodies with different mass ratios orbiting around a common barycenter. Any of these three
     mass ratios could be tidally locked in synchronous orbits, always facing each other with the same side. (Animations: Wikipedia)

Similar was believed for Mercury orbiting the Sun, and that it might be tidally locked with the Sun, always facing it with the same side, but that was later disproved by radar observations in 1965. Strictly theoretically speaking though, it would have been perfectly possible.

So, in short, there is no upper limit to total mass that can be put in GEO. If your mass comes mostly from the Earth itself, then it would obviously have to be smaller than the total mass of it (poor Earth, people should learn to travel light), but if you bring mass from elsewhere (other celestial bodies, maybe asteroids, or the Moon itself?), then your upper mass limit is the patience of the humankind to tolerate your endeavours and the problems they bring along.

Having too large of a mass would, of course, change requirements of the GEO orbit itself, destabilize the Earth's rotation on it's axis (day/night and seasons of the year cycles) and around the Sun (length of year and seasons), change the tidal patterns (that we do depend upon), accelerate atmospheric loss, and all kinds of other uncomfortable side effects.

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  • $\begingroup$ If the satellite massed more than the Earth I wouldn't really say it orbited the Earth. $\endgroup$ – Loren Pechtel Jan 3 '16 at 21:15
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    $\begingroup$ @LorenPechtel Where do I say that? No, they always orbit their common barycenter. Then again, this is semantics and not really relevant to the question which asks about synchronous orbits. In that sense, the Earth is in a "selenosynchronous orbit", even though we don't usually say that it orbits the Moon and it is of course a lot more massive. But it appears at roughly the same position on the Moon's sky all of the time, with libration at not much higher order of magnitude than average GEO satellites' longitudinal drift. $\endgroup$ – TildalWave Jan 3 '16 at 21:35
  • $\begingroup$ As a clarification, Charon doesn't just happen to orbit Pluto at geostationary orbit - Its orbit was quite random, but he tidal forces between the two stopped their rotation respective to each other, so that orbit became geostationary as Pluto's and Charon's day lengths adjusted to match it. $\endgroup$ – SF. Jan 4 '16 at 0:17
  • $\begingroup$ There's about a large library worth of clarifications and nitpickings possible here, but I had to stop somewhere didn't I? I wouldn't bother posting an answer otherwise. Please feel free to edit if you believe I left out something essential, or post a new answer. And please use our Space Exploration Chat for general discussions. This is now over 2 years old answer and I'd really like to move on. Thanks! $\endgroup$ – TildalWave Jan 4 '16 at 0:23
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As of Early 2015, the maximum payload to GEO is 6750 KG using Delta IV Heavy.

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To take TildalWave's answer a little farther: Eventually you'll have enough mass up there that Earth enters the Roche limit of the object you built--goodbye Earth. You'll need something well above Earth's mass for that to happen, though.

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    $\begingroup$ To paraphrase Obi Wan "That's not a moon!". Wait...it still stays the same. Well before you reach the Roche limit, your Satellite stops being a Satellite. $\endgroup$ – Aron Jun 17 '15 at 13:10
  • $\begingroup$ I don't think that could happen anyway, the satellite would hit Earth's Rosche limit while it was being constructed and become unstable before being finished. $\endgroup$ – Magic Octopus Urn May 22 at 17:37
  • $\begingroup$ @MagicOctopusUrn No. Earth's Roche limit is more than Earth's radius below geosync. $\endgroup$ – Loren Pechtel May 22 at 23:20

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