Lanci del Falcon 1: differenze tra le versioni

Versione delle 12:48, 8 set 2009

Versione delle 18:25, 11 set 2009

Riga 17:

==Secondo lancio==

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The second test flight was originally scheduled for January 2007, but was delayed due to problems with the second stage. Before the January launch date, SpaceX had stated earlier potential launch dates, moving from September 2006 to November and December. In December the launch was rescheduled for 9 March, but delayed because of range availability issues caused by a [[Minuteman III]] test flight which would re-enter over Kwajelein. The launch attempt on 19 March was delayed 45 minutes from 23:00 GMT due to a data relay issue, and then scrubbed one minute and two seconds before launch at 23:45 due to a computer issue, whereby the safety computer incorrectly detected a transmission failure due to a hardware delay of a few [[millisecond]]s in the process. The 20 March attempt was delayed 65 minutes, from an originally planned time of 23:00 due to a problem with communications between one of the NASA experiments in the payload, and the [[TDRS]] system.

Il secondo volo di prova fu originariamente previsto per il gennaio 2007, ma fu posticipato per problemi con il secondo stadio. Prima di questa data di lancio, SpaceX ne aveva programmate altre possibili, che andavano dal settembre del 2006 a novembre e a dicembre. A dicembre il lancio fu spostato inizialmente al 9 marzo, ma poi ulteriormente posticipato per problemi di disponibiltà del sito, a causa del volo di prova del [[Minuteman III]] che sarebbe dovuto rientrare su Kjawalein. Il lancio, previsto il 19 marzo alle 23:00 GMT, ebbe un ritardo di 45 minuti, per poi essere annullato un minuto e due secondi prima delle 23:45 per un problema al ripetitore dati, dato il computer di sicurezza aveva erroneamente scambiato per un errore di trasmissione un ritardo [[hardware]] di alcuni millisecondi nel processo. Il tentativo del 20 marzo, programmato per le 23:00 GMT, fu ritardato di 65 minuti per un problema di comunicazioni fra uno dei dispositivi sperimentali [[NASA]] presenti nel carico ed il sistema [[TDRS]]. Il successivo, il 21 marzo alle 00:05 GMT, fu annullato un secondo prima del lancio e dopo che uno dei motori era già stato acceso. Si decise comunque di eseguire un altro lancio lo stesso giorno.

The launch attempt on March 21, 2007 was aborted at 00:05 GMT at the last second before launch and after the engine had ignited. It was however decided that another launch should be made the same day. The rocket was launched successfully at 01:10 GMT on 21 March 2007 with a [[DemoSat]] payload for [[DARPA]] and [[NASA]]. The rocket performed well during the first stage burn. However, during staging, the interstage fairing on the top of the first stage bumped the second stage engine bell.<ref>{{cite news |url=http://www.spacedaily.com/reports/SpaceX_Confirms_Stage_Bump_On_Demoflight_2_999.html |title=SpaceX Confirms Stage Bump On Demoflight 2}}</ref> The bump occurred as the second stage nozzle exited the interstage, with the first stage rotating much higher than expected (a rotation rate of about 2.5 deg/s vs. expected rate of 0.5 deg/s maximum), thereby making contact with the [[niobium]] nozzle of the second stage. Elon Musk reported that the bump did not appear to have caused damage, and that the reason why they chose a niobium skirt instead of [[Reinforced carbon-carbon|carbon-carbon]] was to prevent problematic damage in the event of such incidents. Shortly after second stage ignition, a stabilization ring detached from the engine bell as designed.<ref name="falconf2status">{{cite news |url=http://www.spaceflightnow.com/falcon/f2/status.html |title=Mission Status Center |date=2007-03-20 |publisher=Space Flight Now }}</ref> At around T+4:20, a circular coning oscillation began that increased in amplitude until video was lost. At T+5:01, the vehicle started to roll and telemetry ended. According to [[Elon Musk]], the second stage engine shut down at T+7.5 minutes due to a roll control issue. Sloshing of propellant in the LOX tank increased oscillation. This oscillation would normally have been dampened by the Thrust Vector Control system in the second stage, but the bump to the second nozzle during separation caused an overcompensation in the correction.<ref name="falconf2status"/> The rocket continued to within one minute of its desired ___location, and also managed to deploy the satellite mass simulator ring. While the webcast video ended prematurely, SpaceX was able to retrieve telemetry for the entire flight.<ref>{{cite news |url=http://www.nasaspaceflight.com/content/?cid=5056 |title=Falcon I flight - preliminary assessment positive for SpaceX |publisher=[[NASAspaceflight.com]] |date=2007-03-24}}</ref> The status of the first stage is unknown; it was not recovered due to problems with a nonfunctioning GPS tracking device. The rocket reached a final altitude of 289&nbsp;km (156&nbsp;miles) and a final velocity of 5.1&nbsp;km/s, compared to 7.5&nbsp;km/s needed for orbit.

Il razzo fu lanciato con successo alle 01:10 GMT del 21 marzo 2007, trasportando un [[DemoSat]] per conto della [[DARPA]] e della NASA. Tutto andò bene durante il funzionamento del primo stadio, ma durante la separazione di questo, l'anello interstadio all'estremità superiore andò a collidere con il cono di scarico del motore del secondo stadio<ref>{{cita news|lingua=en|url=http://www.spacedaily.com/reports/SpaceX_Confirms_Stage_Bump_On_Demoflight_2_999.html |titolo=SpaceX Confirms Stage Bump On Demoflight 2}}</ref>.La collisione avvenne non appena l'ugello del secondo stadio uscì fuori dall'interstadio, con il primo stadio che ruotava molto più velocemente del previsto (una velocità angolare effettiva di 2,5 gradi al secondo contro una prevista di non più di 0,5 gradi al secondo), entrando così in contatto con l'ugello di [[niobio]] del secondo stadio. [[Elon Musk]] riferì che la collisione non sembrava aver causato danni, la ragione per cui si era scelto un rivestimento di [[niobio]] anziché uno di [[carbonio-carbonio rinforzato]] era proprio quella di prevenire danni problematici in tali incidenti. Subito dopo l'accensione del secondo stadio fu rilasciato un anello di stabilizzazione dal cono del motore, come previsto dalla progettazione<ref name="falconf2status">{{cita news|lingua=en|url=http://www.spaceflightnow.com/falcon/f2/status.html |titolo=Mission Status Center |date=2007-03-20 |pubblicazione=Space Flight Now }}</ref>.

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The launch attempt on March 21, 2007 was aborted at 00:05 GMT at the last second before launch and after the engine had ignited. It was however decided that another launch should be made the same day. The rocket was launched successfully at 01:10 GMT on 21 March 2007 with a [[DemoSat]] payload for [[DARPA]] and [[NASA]]. The rocket performed well during the first stage burn. However, during staging, the interstage fairing on the top of the first stage bumped the second stage engine bell.<ref>{{cite news |url=http://www.spacedaily.com/reports/SpaceX_Confirms_Stage_Bump_On_Demoflight_2_999.html |title=SpaceX Confirms Stage Bump On Demoflight 2}}</ref> The bump occurred as the second stage nozzle exited the interstage, with the first stage rotating much higher than expected (a rotation rate of about 2.5 deg/s vs. expected rate of 0.5 deg/s maximum), thereby making contact with the [[niobium]] nozzle of the second stage. Elon Musk reported that the bump did not appear to have caused damage, and that the reason why they chose a niobium skirt instead of [[Reinforced carbon-carbon|carbon-carbon]] was to prevent problematic damage in the event of such incidents. Shortly after second stage ignition, a stabilization ring detached from the engine bell as designed.<ref name="falconf2status">{{cite news |url=http://www.spaceflightnow.com/falcon/f2/status.html |title=Mission Status Center |date=2007-03-20 |publisher=Space Flight Now }}</ref> At around T+4:20, a circular coning oscillation began that increased in amplitude until video was lost. At T+5:01, the vehicle started to roll and telemetry ended. According to [[Elon Musk]], the second stage engine shut down at T+7.5 minutes due to a roll control issue. Sloshing of propellant in the LOX tank increased oscillation. This oscillation would normally have been dampened by the Thrust Vector Control system in the second stage, but the bump to the second nozzle during separation caused an overcompensation in the correction.<ref name="falconf2status"/> The rocket continued to within one minute of its desired ___location, and also managed to deploy the satellite mass simulator ring. While the webcast video ended prematurely, SpaceX was able to retrieve telemetry for the entire flight.<ref>{{cite news |url=http://www.nasaspaceflight.com/content/?cid=5056 |title=Falcon I flight - preliminary assessment positive for SpaceX |publisher=[[NASAspaceflight.com]] |date=2007-03-24}}</ref> The status of the first stage is unknown; it was not recovered due to problems with a nonfunctioning GPS tracking device. The rocket reached a final altitude of 289&nbsp;km (156&nbsp;miles) and a final velocity of 5.1&nbsp;km/s, compared to 7.5&nbsp;km/s needed for orbit.

SpaceX characterized the test flight as a success, having [[Technology readiness level|flight proven]] over 95% of Falcon 1's systems. Their primary objectives for this launch were to test responsive launch procedures and gather data.<ref name="demoflight_2_launch_update_12"/> According to Musk, the SpaceX team intends to have both a diagnosis and solution vetted by third party experts. Musk believes the slosh issue can be corrected by adding baffles to the second stage LOX tank and adjusting the control logic. Furthermore, the Merlin shutdown transient can be addressed by initiating shutdown at a much lower thrust level, albeit at some risk to engine reusability. The SpaceX team intends to work the problem to avoid a recurrence as they change over into the operational phase for Falcon 1.<ref name="Space28">{{cite news |url=http://www.space.com/news/070328_spacex_falc1test_updt.html |publisher=space.com |title=SpaceX Declares Falcon 1 Rocket Operational Despite Less than Perfect Test |date=2007-03-28}}</ref>