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Satellite Lifespan

Discussion in 'DIRECTV General Discussion' started by jeffreydavisjr, Aug 22, 2007.

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  1. jeffreydavisjr

    jeffreydavisjr Legend

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    I was reading up on the D10 satellite launched earlier this year. It stated it had a 15 year life span. I was just wondering. What happens in 15 years?

    Will the satellite just fall from the sky and land in the south pacific?

    Or will it be brough back to earth?

    How does this effect DirecTV service? Do they expect other satellites in the future to make this one obsolete?

    Questions, questions...
     
  2. davring

    davring Hall Of Fame

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    I am by no means an expert, but it is my understanding that they begin to run out of fuel. I have read that some are older than planned and still function in a limited capacity. Hopefully someone will chime in here with much more to add.
     
  3. jeffreydavisjr

    jeffreydavisjr Legend

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    But the D10 is solar powered....

    "18,000 Watts of Space Craft Power"
     
  4. davring

    davring Hall Of Fame

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    The fuel is used to keep it in proper position, they do drift about.
     
  5. mhayes70

    mhayes70 New Member

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    I have always wonder the same thing. What do they do with them when they have lived there lifespan?
     
  6. say-what

    say-what Active Member

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    Well, regardless of when a satellite ceases to function, they all will eventually fall to earth, most of the sat will burn up as it breaks apart re-entering earth's atmosphere and what doesn't burn up will crash into the earth, who knows where.......

    15 years is just the expected life span. Some last longer, some don't. But as we near the end of the expected lifesapn, replacements are planned.
     
  7. samw

    samw Cool Member

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    Well, here's the thing. D* execs have an exit strategy that they believe they will complete well within the 15 year lifespan. After they cash all their options and milk shareholders for everything they can, what to do after the bird drops out of the sky becomes someone else's problem.

    Ok, seriously, managing satellite assets is just like managing any other corporate asset. Nearly every asset needs to be upgraded/replaced/scrapped at some point in time. When D10 becomes obsolete and is taken out of service, it will be scrapped (i.e. controlled de-orbit and burned up in our atmosphere). New satellites will have been launched to take its place.

    I believe most/all satellites carry fuel to power the on board thrusters needed to position/re-position the satellite. Even though it's in its orbital slot, periodic adjustments are needed and this consumes the on-board fuel reserves.
     
  8. LameLefty

    LameLefty I used to be a rocket scientist

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    By international treaty, space vehicles and satellites are generally supposed be designed to safe themselves so residual fuels and other stored energy (i.e., batteries, fuel cells, RTGs, etc.) are precluded from causing the vehicle to explode or break apart. Exploding rocket stages and satellites (caused by dead or dying controls allowing residual propellants to react) have historically been a big contributor to orbital debris problems ("space junk").

    GSO satellites are supposed to be designed and operated such that right before they are about to run out of usable propellant, they raise their orbits by enough to get them out of the geostationary orbit belt and thus out of the way of the rest of the sats and any replacement vehicles. They don't usually have enough fuel to lower their orbits much and almost certainly wouldn't have enough to totally deorbit. Lowering the orbit also clutters up the transfer orbits needed for replacements. So they go higher up to die, a "graveyard orbit."
     
  9. old7

    old7 Godfather

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    Satellites are frequently sent into a graveyard orbit when have reached the end of their operational lives.
    LameLefty beat me to the punch. :)
     
  10. harsh

    harsh Beware the Attack Basset

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    So they can hold in this "graveyard orbit" and not descend back through the Clarke Belt at any time? I think the assumption among outsiders is that all orbits decay and eventually, everything will re-enter the Earth's atmosphere.

    As supporting material for your "space junk", I encourage readers to check out the TLEs for debris and see how many pieces of that Chinese satellite that they are tracking.
     
  11. M3 Pete

    M3 Pete AllStar

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    all orbits decay and they will eventually fall to earth. How long does that take from graveyard orbit?

    From a bit of internet research, it supposedly takes a few hundred years to decay from graveyard orbit to geostationary, and longer still to reenter the atmosphere. Sounds like we'll have a signficant problem on our hands in couple hundred years as the dead satellites begin to interfere with the active ones. Hope our kids figure out how to deal with it.
     
  12. Stuart Sweet

    Stuart Sweet The Shadow Knows!

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    The way I read it there's already a "space junk" problem. Not a lot of stuff but some of it is going around at high relative velocities.
     
  13. Everyperson

    Everyperson AllStar

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    Hmmm...When it's falling back to earth, will the HD picture improve since it's closer to earth?:D:lol:
     
  14. Araxen

    Araxen Icon

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    That's of course if China doesn't blow them all up first and cause a really big problem.
     
  15. Halo

    Halo Godfather

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    Fuel: Using XIPS (xenon ion propulsion system) requires only about 5KG of fuel per year for station keeping. I'm only aware of one XIPS failure but they haven't been around that long to be certain that they'll still be working after 15 years. There are two backup XIPS thrusters. There are also bipropellant thrusters which can be used for stationkeeping or orbital maneuvering.

    Power: 18 kw (and the boeing 702 factsheet has 16kw as the predicted end of life power). XIPS requires more than 4kw each day for 30 minutes. So many high powered transponders also require a lot of power. Also, the panels must produce power to charge batteries for the several hours each day when D10 is in eclipse.
    Batteries can fail which are just as vital as the panels because D10 must operate at near full power 24 hours/day. Panels on earlier 702 birds had a fogging problem which reduced power so much that both the XIPS and transmission capability were compromised.

    Momentum wheels can fail. This can reduce the ability to precisely point the sat.
    TWTAs can fail but there are several backups. The SCP(satellite control processor) can fail but has a backup. Radiators, power amps, solar array motors. Plenty of things can go wrong but Directv has been extremely lucky with their fleet so far.
     
  16. ProfLonghair

    ProfLonghair Hall Of Fame

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    The real thing is, we here at Deep 13 find some hapless contractors to send up to them and show them really, really bad movies.
     
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