Mustard Mar 12 Nov 2013 - 15:29
C'est étrange que cette réhausse n°4bis, n'ai pas ramené l'orbite à 100.000 comme prévu initialement pour la réhausse 4.
Est ce uniquement dans le but de réduire le temps d'allumage de la 5ème et dernière réhausse ?
Pour revenir au problème de samedi.
A priori, de ce que je crois avoir compris, lors des 3 premières réhausses, seul le systeme primaire de propulsion était utilisé. Pour la 4eme, ils ont ut
ilisé en plus le systeme secondaire (les RCS il me semble), ce qui a provoqué un problème. Il semble qu'ils ne peuvent pas etre utilisé ensemble. Le soft a donc été modifié pour que l'ont ne puisse plus les activer ensemble.
Ci dessous la source, dites moi je me me gourre car mon anglais (surtout technique) n'est pas top et je ne suis pas certain que ce soit exactement cela.
Spceflight101 a écrit:Later, ISRO reported what had occurred. The fourth Midnight Maneuver was the first burn during which the vehicle’s redundant coils of the solenoid flow control valve of the engine were checked out. During the first three burns, only the primary system was in use. As part of a sequence of operations, the “primary and redundant coils were energised together” which caused propellant flow to the engine to stop. Also tested during the burn was the thrust augmentation by the attitude control thrusters which continued to burn after the LAM had shut down.
MOM is equipped with a single 440-Newton Liquid Apogee Motor part of a redundant main propulsion system plumbing assembly including redundant propellant lines, valves and controllers. The spacecraft uses eight 22-Newton thrusters for attitude control during burns and for smaller maneuver.
ISRO determined both coils of the valve can not be used simultaneously which will be prevented from occurring again by a software patch that will be implemented. Operating the coils independently in sequence is possible to ensure redundancy of the system.
One of the big advantages of MOM’s trajectory is that the spacecraft spends the first weeks of its flight in close proximity to Earth before departing for Mars allowing teams to test the vehicle. Also, the chosen flight profile using an incremental orbit-raising scheme is relatively forgiving as a missed or aborted burn does not mean the loss of the mission. Taking advantage of MOM still being in orbit around Earth, ISRO has put the vehicle’s gyros, accelerometers, star trackers, flight control system and flight software through their paces, showing that all of those systems were functioning as advertised.
Dernière édition par Mustard le Mar 12 Nov 2013 - 15:44, édité 1 fois