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It's my understanding a geosynchronous satellite will put itself in a graveyard orbit just before it dies.

How many dead sats are in GEO or in neighboring graveyard orbits?

What is their total mass?

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  • $\begingroup$ I can find the number of unclassified satellites in the belt, but I'm having trouble getting the number of active satellites in the group. Hopefully I can get this figured out... $\endgroup$
    – PearsonArtPhoto ♦
    Commented Jun 29, 2015 at 17:39
  • $\begingroup$ So, I'm going to remove the last bit, as it is an interesting question in and of itself. Feel free to ask a question specifically geared towards it. $\endgroup$
    – PearsonArtPhoto ♦
    Commented Jun 29, 2015 at 18:48

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This is a difficult question to answer, so I'm going to take a stab based off of a few assumptions.

  1. GEO satellites are ones with a period between 1430-1450 minutes (Standard definition from NORAD)
  2. I have no knowledge of classified satellites, those will not be included.
  3. I'm going to assume you mean GSO satellites (Geostationary).
  4. Active GEO satellites have a near 0 inclination, dead ones will have a non-zero inclination. Why? GSO satellites drift in inclination over time.
  5. GSO satellites will have an eccentricity near zero, dead or living. This doesn't vary as much as the inclination.

Okay, so given those, what are we looking at? Norad lists 804 objects in that orbital period range in orbit. Of these, here are some statistics:

  • 797 have a perigee of at least 35000 km (Low eccentricity)
  • 696 are considered payloads.
  • 18 of the payloads have very large inclinations (Greater than 16). These were probably not launched into GSO
  • 307 have inclinations less than 0.5 degrees. These are probably the active GSO satellites.

I'm going to remove the large inclination satellites from consideration. That leaves 371 payload objects near GSO that are not being maintained in inclination, and thus are probably dead.

As for the mass of these, assuming an average of 1800 kg, which is the average dry mass of a satellite, that means there is about 668,000 kg of satellites in GEO that aren't being properly maintained.

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    $\begingroup$ 20 tons is a bit much. As per UCS Satellite Database that lists 465 GEO satellites, only counting GEO satellites with all the relevant data, average wet mass is 3,437.80 kg and average dry mass 1,788.71. They have on average 6,663.66 Watts of power available to them, tho that has increased sharply in two decades and has almost doubled. By 2018, 238 of them are expected to reach EOL (launch mass 754,800 kg, dry mass 289,888 kg, and power of 919,800 W). $\endgroup$
    – TildalWave
    Commented Jun 29, 2015 at 19:15
  • $\begingroup$ I changed to the dry mass figure you gave. I'm sure there's a few inaccuracies, it might be that the UCS includes active non-maintained GEO satellites, and classified satellites, while my list includes neither. $\endgroup$
    – PearsonArtPhoto ♦
    Commented Jun 29, 2015 at 19:25
  • $\begingroup$ Thank you! The Norad list you mention -- is it online? $\endgroup$
    – HopDavid
    Commented Jun 29, 2015 at 20:52
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    $\begingroup$ @HopDavid Yup: satellitedebris.net/Database/index.php $\endgroup$
    – TildalWave
    Commented Jun 29, 2015 at 22:40
  • $\begingroup$ @PearsonArtPhoto I mentioned this answer in one of my blog posts. hopsblog-hop.blogspot.com/2015/05/… $\endgroup$
    – HopDavid
    Commented Jun 30, 2015 at 23:41

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