Posted 04 September 2012 - 08:36 AM
The whole idea of reusing or harvesting dead satellites, whether in GSO or even LEO, is just pie in the sky dreaming for the current generation (and probably the next two or three). Aerospace engineering is always a cutting-edge compromise between terrifically high energy requirements and very low mass-margins. It takes a LOT of energy to accelerate something to orbit in the first place. So even launching the simplest LEO satellite is on the order of several millions of dollars, unless it's a very minimal "microsat" hitching a ride up using excess capacity on a launcher for another payload. GSO launches are substantially more - in the range of a hundred million dollars or more, exclusive of the cost of the satellite. And once in orbit, every maneuver costs fuel, more of that precious, expensive launch mass you're paying so much to accelerate up to such high speeds.
Bringing anything down means the reverse: all that energy you've added to the system has to be depleted, either by using a lot of fuel to slow down quickly, or by sliding through the friction of the atmosphere (which creates heat on the order of several thousand degrees over 20 - 30 minutes of entry. That means you need a heat shield - more mass that is useless in orbit until you need it to return. There's been work done on inflatable heat shields. Perhaps one could tele-operate a harvester to clip off the deployed antennas and solar arrays, then strap the hulk to a module with a deployable heat shield and parachute array - but what's the point? The components will be old and obsolescent at best. The real costs of a satellite are in design and construction labor, not the materials. That, plus the expense of the launch, which you'd have to re-incur even if you could retrieve and refurbish the satellite in the first place. And those large PV arrays and antennas, cut free and floating up above GSO in the graveyard orbit, will be harder to track and avoid than a single, intact dead satellite.
If launch costs were a fraction of what they are today, the whole idea might make some kind sense but as it is, it's just a blue-sky brainstorming project.
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Directv since 1997
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