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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. Feb 8, 2010 #2661 of 10270
    LameLefty

    LameLefty I used to be a rocket scientist

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    Inclination won't ever equal zero exactly. It might get a couple orders of magnitude smaller than it is now, but since the satellite will have to bias itself toward the NWUF for BSS spotbeam testing anyway, so long as it has a lock on the carrier beacon, inclination won't have to be as low as would ideally be in regular operation.
     
  2. Feb 8, 2010 #2662 of 10270
    Hoosier205

    Hoosier205 Active Member

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    Any guesses for which day that gap reaches zero?
     
  3. Feb 8, 2010 #2663 of 10270
    Jeremy W

    Jeremy W Hall Of Fame

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    Wednesday.
     
  4. Feb 8, 2010 #2664 of 10270
    Sixto

    Sixto Well-Known Member

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    Recent models have indicated 2/9, but final tuning at the end usually takes a few days.

    D11 average (5.5km/hr): 2/9/10 11:46am

    Last TLE (perigee) average (4.93km/hr): 2/9/10 3:59pm

    Last-10 TLE (perigee) average (5.92km/hr): 2/9/10 9:09am

    Last-20 TLE (perigee) average (5.51 km/hr): 2/9/10 11:42am

    Last-20 TLE (gap) average: 2/9/10 4:30pm

    Most likely by end of week for sure.
     
  5. Feb 8, 2010 #2665 of 10270
    Sixto

    Sixto Well-Known Member

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    For comparison:
    Code:
    [B]
    	D10	D10	D10	D11	D11	D11	D12	D12	D12
    [U]Day#[/U]	[U]Low[/U]	[U]High[/U]	[U]Gap[/U]	[U]Low[/U]	[U]High[/U]	[U]Gap[/U]	[U]Low[/U]	[U]High[/U]	[U]Gap[/U][/B]
    29	34923	36787	1864	30615	41065	10450	33948	37410	3462
    30	                 				34196	37445	3249
    31	35603	36177	574	30883	40871	9988
    32	35644	36057	413	31115	40623	9508	34409	37150	2741
    33	35630	36051	421	31309	40411	9102	34419	37149	2730
    34	35663	35964	301	31369	40366	8997	34450	37155	2705
    35	35740	35919	179				34715	36952	2237
    36	35737	35864	127	31742	39996	8254	34739	36886	2147
    37	35739	35876	137	31866	39844	7978	35004	36635	1631
    38	35742	35809	67				35030	36564	1534
    39							35344	36351	1007
    40	35784	35789	5	32302	39428	7126	35484	36200	716
    41	35784	35787	3	32285	39398	7113	35584	36081	497
    ...
    61				35352	36444	1092
    62				35350	36345	995
    63				35496	36217	721
    64				35600	36052	452
    65				35739	35884	145
    66				35747	35804	57
    67				35786	35792	6
    68						
    69				35785	35789	4
    70				35786	35788	2
     
  6. Feb 8, 2010 #2666 of 10270
    P Smith

    P Smith Mr. FixAnything

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    Any chance to include inclination into the comparison chart ? Seems to me each apogee/perigee correction followed by inclination correction.

    Non zero inclination would be a source of 'wobulation' of the sat and would require additional fuel consumption to keep the 'bus' and antennas and solar panels orientation.
     
  7. Feb 8, 2010 #2667 of 10270
    Sixto

    Sixto Well-Known Member

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    not easily. :) wasn't tracking inclination last time.
     
  8. Feb 8, 2010 #2668 of 10270
    Jeremy W

    Jeremy W Hall Of Fame

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    I don't think that word means what you think it means...
     
  9. Feb 8, 2010 #2669 of 10270
    LameLefty

    LameLefty I used to be a rocket scientist

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    Not necessarily. If the 702 bus uses control moment gyros (and it probably does) the thrusters only have to be used for momentum dumping. And even it doesn't use CMGs, the BSS spotbeam footprints are certainly large enough to handle small offsets from nominal inclination.
     
  10. Feb 8, 2010 #2670 of 10270
    P Smith

    P Smith Mr. FixAnything

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    Could we calculate movement of one spot-beam (radius ~200 mi) on Earth surface if inclination is say 0.1 degree ?
     
  11. Feb 8, 2010 #2671 of 10270
    LameLefty

    LameLefty I used to be a rocket scientist

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    Go right ahead. It's an exercise in trigonometry. However, since Directv has already said in FCC filings that they'll be biasing the entire satellite bus to aim the beams at the uplink facility, the inclination doesn't matter much at all.
     
  12. Feb 8, 2010 #2672 of 10270
    Sixto

    Sixto Well-Known Member

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    D11 inclination at end (1000 to 0 gap) was .04-.06 every TLE.
     
  13. Feb 8, 2010 #2673 of 10270
    P Smith

    P Smith Mr. FixAnything

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    Well, then if inclination is not zero, the sat orientation must be correcting all the time for holding spot-beam to particuar area (could be +/- 25 mi).
    [By quick thought 0.1 degree incliantion could move spot-beam for 100 mi.]
     
  14. Feb 8, 2010 #2674 of 10270
    HoTat2

    HoTat2 Hall Of Fame

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    Los...
    Just a note: :)

    IIRC Directv will be biasing D12's orientation to perform "gain transfer testing" for both its Ka band spotbeam and BSS payloads.

    The Ka spotbeams during their testing phase will be successively positioned over the Castle Rock, CO. uplink facility. And BSS over the NWUF at Moxee, WA.
     
  15. Feb 8, 2010 #2675 of 10270
    LameLefty

    LameLefty I used to be a rocket scientist

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    Yep. That's what thrusters and CMGs are for.

    Now, that said, inclination will drop by about one order of magnitude (a leading zero after the decimal place) before D12 settles down into it's nominal operating configuration.
     
  16. Feb 8, 2010 #2676 of 10270
    Hoosier205

    Hoosier205 Active Member

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    I just have to say this yet again...

    Thank you and kudos to everyone who contributes information and explanations in this thread. I consider myself to be fairly intelligent, but reading this thread at times makes me second guess whether or not I have suffered from some sort of brain damage recently. I just wait on one person to post something and another person to translate that for people like me.

    Thank you once again.
     
  17. Feb 8, 2010 #2677 of 10270
    slimoli

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    I second that. What these guys are doing (for free!) is better than attending a University.
     
  18. Feb 8, 2010 #2678 of 10270
    Jeremy W

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    Thirded. These threads have taught me pretty much everything I know about orbital mechanics.
     
  19. Feb 8, 2010 #2679 of 10270
    davring

    davring Hall Of Fame

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    It amazes me as well all the science, engineering and mathematics involved and the folks here who devote so much time and effort to make it available and understandable to us commoners. Maybe these same people can help Toyota figure out how to make cars stop when they are supposed to:)
     
  20. Feb 8, 2010 #2680 of 10270
    Sixto

    Sixto Well-Known Member

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    this next TLE hopefully is a mistake. :)
     
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