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SixtoReport: D12 Satellite Info in Post#1 - Live!

Discussion in 'DIRECTV General Discussion' started by Sixto, Jul 27, 2008.

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  1. Apr 26, 2010 #7301 of 10270
    oldfantom

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    The inclination has been at that same position at least once during the testing cycle. So, I would have to say it might just be the testing wobble we have been seeing. Hindsight might be our best indication of the start of the drift.
     
  2. Apr 26, 2010 #7302 of 10270
    syphix

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    It should be noted, however, that inclination (now at .08) is the highest it's been since it was parked. This MAY be a sign that the bird is on the move. It's expected to start drifting "soon".

    But oldfantom is correct: we may not see it BEGIN to move, only notice that it IS moving some 1-3 days into the drift.
     
  3. Apr 26, 2010 #7303 of 10270
    flyingtigerfan

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    Some of y'all ain't firin' on all thrusters, XIPS or not.

    ;-)
     
  4. Apr 26, 2010 #7304 of 10270
    Jeremy W

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    I believe that the increased inclination is a sign that they have lost control of the satellite.





    :lol:
     
  5. Apr 26, 2010 #7305 of 10270
    HIGHWAY

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    so if the drift begins on wednesday we may not see the update till may and no that the drift has started. :)
     
  6. Apr 26, 2010 #7306 of 10270
    HoTat2

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    Again remember to raise the orbit you must actually fire the thrusters in the direction of travel for the satellite along its natural west to east course (for all prograde orbits that is) to increase its velocity.

    This will propel the satellite into a "transfer ellipse" with the perigee point of the ellipse tangent to the radius of the initial lower orbit at the position where the thrusters initially fire to cause the increase in velocity. And the apogee point is tangent to the radius of the new higher orbit and at a lower velocity.

    See diagram and explanation here;

    http://www.dbstalk.com/showthread.php?p=2436009#post2436009

    The opposite occurs for lowering the orbit of course...

    At least this is for the standard "Hohmann transfer orbit" which I assume DirecTV will use to drift D12 from 76° to 103° nom. because of it has the greatest fuel efficiency.
     
  7. Apr 26, 2010 #7307 of 10270
    slimoli

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    Will the D12 signal be any stronger that the other birds ? We have a lot of bad weather here in Florida and I wonder if there is anything new that woud make the reception less vulnerable to the weather.
     
  8. Apr 26, 2010 #7308 of 10270
    GoPokes43

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    Thanks HoTat. And, to apply a little common sense to the equations, to move to a higher orbit is akin to escaping earth's gravity. Accordingly, velocity needs to be added (though it will need to be slowed to be put in the correct circular orbit). Conversely, if the satellite is stopped, it won't increase it's orbital height - it will fall to the earth.
     
  9. Apr 26, 2010 #7309 of 10270
    jacmyoung

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    Correct, that is why I avoided the word "velocity". From the standpoint of a J6P, what I have been talking about is the "speed", i.e. the speed the sat travels in the direction of the orbit course, when the orbit is raised, such "speed" is reduced. The higher the orbit, the slower the sat travels in the direction of the course of the orbit.

    If you fire in the direction of your own path of travel, of course you "slow down" in the direction of the path of your own travel. But in this case since as you fire, you also move up, so the velocity works differently.
     
  10. Apr 26, 2010 #7310 of 10270
    James Long

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    Keeping the relativity straightened out is the problem. Telling J6P that accelerating will slow the satellite down is counter intuitive. Keeping to ONE standard might help him understand, especially if J6P has emptied a couple of cans before reading the post.
     
  11. Apr 26, 2010 #7311 of 10270
    Doug Brott

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    I consider myself j6p in this discussion .. :lol:

    "speed" to me is if I were standing on Earth watching it move across the sky (of course making the erroneous assumption that I can actually see it from Earth).

    So it's a simple (sort of) distance/time calculation .. and that's your speed.
     
  12. Apr 26, 2010 #7312 of 10270
    James Long

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    So what is faster? The NASCAR running down the backstretch in the distance or the fly that just flew in front of your face?
     
  13. Apr 26, 2010 #7313 of 10270
    Doug Brott

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    What if I don't see both? :)

    I don't know actually .. I do know (suspect) that the NASCAR could sustain the speed longer than the fly.

    I'm not a rocket scientist and don't play one on the Internet ... :p
     
  14. Apr 26, 2010 #7314 of 10270
    TDK1044

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    It seems to me that the only relevant post in this thread is post #1. :)
     
  15. Apr 26, 2010 #7315 of 10270
    jacmyoung

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    I agree with your definition of "speed" in this case, as I said this has been what our J6Ps meant it to be.

    When we stand on the surface of the earth looking at that sat directly above us, the reference point will be the same sat without the firing to move, compared to the same sat that fired its thrust to move, from our vantage point, the latter would appear moving slower in speed, compared to the one that did not fire, i.e. the latter would appear "falling behind" the earlier. In this case it was actually in part because the latter actually did "slow down" in the direction that we could see.

    What we J6Ps cannot see was the latter also was moving away from the earth, but as I have said, what we J6Ps don't see, it does not count:) And if the scientists cannot understand, then the science has no future:)
     
  16. Apr 26, 2010 #7316 of 10270
    James Long

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    It just seems that a distant observer would be a poor source of an estimate. The fly could be out of your range of vision before seeing it registered. The NASCAR would take longer to clear your range of vision.

    [​IMG]
    The imaginary person riding the satellite would be traveling "geostationary" at an orbital velocity 11,066 km/hr= 3.07 km/sec (6,876 miles/hr). This is following the orbit circumference of 264,869 km (164,582 miles), 35,785 km (22,236 miles) above the equator.

    Now take two imaginary people riding satellites side by side. One is the control ... he remains locked in at the same velocity and height. The other one fires thrusters behind him pushing him faster (J6P). But this "faster" also pushes him higher along that transfer orbit and he watches the other satellite (the control in this experiment) fall below but ahead of him. Then he fires thrusters ahead of him slowing him down (J6P). This "slower" allows him to fall back into a new geostationary orbit behind the other satellite (perhaps 19,872 km / 12,339 miles behind the other satellite - or 27 degrees of movement - if the thrusters are timed right).

    If he wanted to move ahead of the other satellite he would fire thrusters ahead of him first to drop to a lower orbit, run closer to the Earth than the geostationary satellite then fire thrusters behind him to regain speed and fall in ahead of the other satellite.

    Close enough?
     
  17. Apr 26, 2010 #7317 of 10270
    Ernie

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    Thanks for that. My original post was about speed after it reached the drift orbit (which is needed to understand the westward drift). People seemed to get confused by Lefty's (correct) statements about what has to happen at the start of moving to the drift orbit. Your post tied them together nicely.

    Now you do bring up an interesting question though. Someone (several people?) have calculated the relative drift speed for a 20 day drift at 41 km/hr (which my calculator agrees with). Reducing the Clarke belt orbital speed by that amount and plugging that back into to orbit calculator yields an altitude 310 km higher. Maybe there aren't any satellites in graveyard orbits yet, or maybe they had to wait a few days extra for one to get out of the way (and causing consternation among DBSTalk users).

    Ernie
     
  18. Apr 26, 2010 #7318 of 10270
    Skyboss

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    So if a satellite farts in space, does anyone hear it? :shrug:
     
  19. Apr 26, 2010 #7319 of 10270
    jacmyoung

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    The reason the above example will not work with the J6Ps is, it is counter to our understanding. There were several pilots here who had tried to use their flight experience to try to make sense of this, they failed, not because they are the less bright of the J6Ps, in fact I think they are the brighter among our J6Ps, but even they were confused, how do you expect us not so bright J6Ps to follow?
     
  20. Apr 26, 2010 #7320 of 10270
    jacmyoung

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    Even the sat cannot hear its own fart because there is no air:)
     
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