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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/A6KZMXNHRIYEAMB37UIT37NOPDZ6MKUA/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "15CB4127C93E4DEEABF791BE605F132D@master", "message_id_hash": "A6KZMXNHRIYEAMB37UIT37NOPDZ6MKUA", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/A6KZMXNHRIYEAMB37UIT37NOPDZ6MKUA/?format=api", "sender": { "address": "f.grappi (a) tin.it", "mailman_id": "4b7c00748d5b4cff8dcc1d00a899cb5c", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/4b7c00748d5b4cff8dcc1d00a899cb5c/emails/?format=api" }, "sender_name": "Francesco Grappi", "subject": "[amsat-bb] I: Re: Was HEO naivete;\tnow GEO rideshare frequency choice, etc.", "date": "2009-02-10T07:38:34Z", "parent": null, "children": [ "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/OGWVA3VKGDPOZ45TEAAMH6ERWPKFFNK7/?format=api" ], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Hi Peter DB2OS,\n\nThank you very much for your precise step by step satellites\nhistory explanation.....hoping that the human community can\nlearn from these mistakes and never repeat these more....\n..waiting for P3-E and P5-A and ....\"fingers crossed\"...\n\n73'\nFrank IW4DVZ\n \n\n\n-----Messaggio originale-----\nDa: [email protected] [mailto:[email protected]] Per conto di\nPeter Guelzow\nInviato: lunedì 9 febbraio 2009 23.49\nA: [email protected]\nOggetto: [amsat-bb] Re: Was HEO naivete; now GEO rideshare frequency choice,\netc.\n\n\nP3-B\nSomeone forgot that P3-B (OSCAR-10) was hit by the last rocket stage of\nthe launcher, when they neutralized that stage by venting the remaining\nfuel. Unfortunatly in the wrong direction...\nOSCAR-10 was hit, Antennas were damaged, the S/C spin was reverse (!)\nand the sun was shining on top of the spacecraft instead of illuminating\nthe solar panels !!!\nThe S/C was completely out of control, loosing rapidly it's battery\ncapacity, getting into harsh temperatures due to totally wrong sun\nangles and thermal control... The S/C would have been dead and lost,\nif Karl Meinzer DJ4ZC would have not started his amazing rescue\noperation by completely re-programming the IHU on-the-fly. First he\nswitched Off all modules and systems which were not urgently needed...\nhe also programmed the beacon off and only sends some telemetry after a\nfew hours... this way he was able to slowly re-charge the battery.\nFinally there was enough electrical energy to start magnetorqueing and\nbringing the S/C into the right attitude. But due to the fact that the\nS/C was spinning \"backwards\", he had to write and upload new navigation\ncode into the IHU.... After several weeks of emergency, finally AO-10\nwas in a favorable orbit to continue commissioning and bringing the S/C\ninto the right attitude for raising the perigee.. if we would have\nwaited too long, perigee would get too close and the bird would have had\nother problems..\n\nDuring the above emergency, the fuel tanks and helium bottle had some\nthermal cycles which were out of the designed specification limits....\n\nEveryone will agree, that this was not the fault of the designer of\nP3-A.... any other spacecraft would have been lost...\n\nThe \"small deviation\" mentioned below was not a design error... to my\nknowledge two bit's in the SEU's programmable register to set the\nburn-time counter were exchanged (wrongly wired in the module to the\nconnector to the IHU) and the test pattern which was used for testing\ndid not showed this... \nDue to the longer than planned burn-time, the Helium bottle temperature\nwent shortly below the lower specified limit. Again, this was not a\ndesign flaw or any other mistake...\nOne can argue if the burn-counter-problem or the emergency caused by the\ncollision with the last rocket stage after seperation caused the leakage\nin the high pressure helium system... but that's history anway..\n\nP3-C (OSCAR-13)\nThe propulsion system worked perfectly and the planned orbit was reached\nexactly. Several experts (including from NASA) were involved in the\nplanning of OSCAR-10's orbit, which was supposed to be safe / stable for\na long long time...... Only several years later, OE1VKW Viktor\nKudielka was so first one who predicted a premature re-entry of OSCAR-13...\nKudielka V., /Long term Predictions for Highly Elliptic Satellite\nOrbits/, Amsat-DL Journal, Jun 1990. pps 5-7. (In German).\nNobody can be blamed... but a lot was learned after this discovery,\neven in the professionally world..\n\nP3-D (OSCAR-40)\nThe catastrophic failure of the propuslion system was not a design\nerror, it was 100% human failure... The 400N engine was the same\nwhich was used before on AO-10 and AO-13. Unfortunately \"almost\".. the\nengine which was donated to us, was used for some qualification tests,\nbut 100% functional and 100% OK.. But it had a small modification used\nfor the qualification.. a venting hole, which was secured with an\nadditional screw or cap.. normally it's just a hole.. only very few\npeople knew about it and unfortunately nobody asked what it was,\nalthough it was \"red\".... during the final and launch integration\nthis was hidden and nobody noticed it. During some early testing in the\nintegration lab in Florida, this valve was never used at it was\nrecommended to not use it too often during \"dry test\" for reliability\nissues.. Later during our intense failure analysis we found a picture\nfrom the earlier integration phase, which showed the engine valve with\nthis red cap in place.... arghhh...\nAfter the first sign of a malfunction of the engine, it would have been\nbetter to take more time to analyze the behavior... but there was some\nkind off pressure and afterwards everybody knows it better anyway.. \nI can only tell, that the the process which resulted in the catastrophic\nengine failure was completely understood in the aftermath...\nAnd still... we had almost 4 years to work with this wonderful\nspacecraft on S-band... even with very small antennas... most of the\ntechnology we wanted to test were successfully tested and proofed,\nincluding the Arcjet which was used to raise the perigee, the momentum\nwheels, etc... the discovery of an additional (temorary?) radiation\nbelt was also due to AO-40's CEDEX... and so on...\n\nHowever, if you ever want another HEO, than there is no way around a\npropulsion.... As with P3-D some well known companies which design\npropulsion systems will be involved in the design and qualification of\nP3-E and P5-A's propulsion system....\n\n73s Peter DB2OS\n\n\n\n\n\n\n\n\nNigel Gunn G8IFF/W8IFF wrote:\n> Paul Williamson wrote:\n> \n>> \"The first burn went relatively well -- there was a small deviation from the\nexpected burn duration, which placed the spacecraft perigee somewhat higher \n>> \n> than planned. The second burn could not be accomplished because a slow leak in\nthe high-pressure helium system during \n> the week the spacecraft was being\n> reoriented prevented the opening of valves feeding fuel to the thrust\nassembly.\"\n> \n>> The \"small deviation\" is known to be due to a design error in the simple\ndigital logic circuit that controlled the burn duration.\n>> \n>\n> OK. The helium leak was a propulsion system fault. The design error in the\nlogic was human error and is known so can be \n> designed out.\n>\n>\n> \n>> On AO-13, the kick motor worked exactly as planned, and the spacecraft\nachieved the intended orbit. But that orbit could have been chosen better, \n>> \n> as it turned out. The early re-entry after only 8.5 years was not anticipated,\nand probably could have been avoided if \n> we had been smart enough,\n> soon enough.\n>\n> Another \"human error\" Hindsight is wonderful.\n> I don't think we should reject an option that requires propulsion because of\npast errors that are now well understood.\n>\n>\n> \n\n_______________________________________________\nSent via [email protected]. Opinions expressed are those of the author.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n\n", "attachments": [] }