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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/4YLRWIPQ3HOC43KPNGBAV4PHJZMYDGBW/?format=api",
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    "message_id": "BF80E71F312E42BBA9F3FCB8CFA7A1BF@GouldMainPC",
    "message_id_hash": "4YLRWIPQ3HOC43KPNGBAV4PHJZMYDGBW",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/SFN7JHPJGPN2V4ZAERA3SIPU7H7S7BA3/?format=api",
    "sender": {
        "address": "gouldsmi (a) bellsouth.net",
        "mailman_id": "9f2b000d905c4738ab035c94a0dffa89",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/9f2b000d905c4738ab035c94a0dffa89/emails/?format=api"
    },
    "sender_name": "Gould Smith",
    "subject": "[amsat-bb] Re: Satellite in eclipse",
    "date": "2008-01-15T21:47:00Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/SFN7JHPJGPN2V4ZAERA3SIPU7H7S7BA3/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hello Darin,\n\nThe eclipse period depends upon the orbit of the satellite.  In the last \nAMSAT Journal I had a graph of the changing eclipse period of AO-51.\nThe ability to charge the batteries depends upon the surface area of the \nsatellite that has solar cells, how efficient the solar cells are, the \nlength of time the solar cells are exposed to sunlight and the angle of the \nsun on the solar cells.\n\nWith AO-51 we can set the TX output power level for both transmitters.  In \nmy role of managing the satellite I am constantly monitoring the total power \nconsumption of the satellite and making sure that the satellite batteries \nwill sustain that power level during each eclipse period. The batteries are \nrecharged each time the satellite is in the sun.  Determining the TX power \nlevels and what modules are on at any particular time and factoring in the \neclipse time and sun time plus sun angle are all part of managing the \nsatellite and part of being a command station.\nSome smaller satellites may not have space to add the additional control \ncircuitry, it is a trade off.\n\nAO-51 has gone from periods of nearly half an hour of eclipse each orbit to \nno eclipse period over the last 3.5 years.\n\nEssentially it goes back to the basic design of the satellite.  Knowing the \nbasic orbit the satellite will be in, how much surface area is needed to \nsupport X amount of TX power during Y long eclipse periods.  Then designing \na battery charger/regulator to support this and provide the ability to alter \nwhatever is needed to maintain an operational satellite.\n\nIf you interested in the actual systems AMSAT offers a book on AO-51 with \ndescriptions of all the hardware systems and specifications.\n\n73,\nGould, WA4SXM\nAO-51 Command Station\n\n\n----- Original Message ----- \nFrom: \"PDC\" <[email protected]>\nTo: <[email protected]>\nSent: Tuesday, January 15, 2008 3:19 PM\nSubject: [amsat-bb] Satellite in eclipse\n\n\n> At great risk of being thwapped with a clue bat, I'm going to ask this\n> newbie sort of question that may seem stupid but it has me stumped.\n>\n> I read/hear about satellites being in eclipse for too long and running out\n> of battery/shutting down/whatever.  Now, since most of the LEO satellites\n> are in orbits of 100 minutes +/-, I don't understand how they could be in\n> eclipse for more than ~50 minutes.  So the question is...\n>\n> For the satellites that have this eclipse issue, is it that their \n> batteries\n> are essentially expired and can't power the satellite for ~50 minutes \n> (that\n> makes sense to me) based on the charge they get from having the solar \n> panels\n> exposed for ~50 minutes, or is there some mechanism that is totally\n> non-obvious to me that allows a LEO satellite to be in the dark for \n> periods\n> of time much longer than half of each orbit thereby creating a situation\n> where the batteries have to power it in the dark for a very long period of\n> time relative to the orbital period?\n>\n> If it's the former, well, that's obvious enough I guess.  If it's the\n> latter, could someone draw me a picture or point me to a URL that explains\n> how that is possible?\n>\n> Thanks.\n>\n> Darin\n> VE3OIJ\n> _______________________________________________\n> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb \n\n",
    "attachments": []
}