statesman news service
Bangalore,11 November
The Mars orbiter spacecraft faced a hiccup during the fourth orbit-raising exercise  this morning with the spacecraft failing to realize the targeted apogee. According to  Isro, the Mars orbiter   though remained normal with supplementary orbit raising exercise now being planned for tomorrow.
In today&’s operation , the apogee  or farthest distance from the earth, was raised to 78,276 km against the targeted 100,000 km  as the imparted incremental velocity  to the spacecraft  fell short at 35 metres/seconds against the  planned   figure of 130.
The glitch arose when the  flow to the liquid engine stopped after the primary and redundant coils were energised. Since 7 November, Isro has been testing and exercising the autonomy functions progressively, so essential for Trans-Mars Injection and Mars Orbit Insertion. Earlier,  the prime and redundant chains of gyros, accelerometers, 22 Newton attitude control thrusters, attitude and orbit control electronics   besides   the associated logics for their fault detection isolation  and reconfiguration went off smoothly.
The prime and redundant star sensors have been functioning satisfactorily. The primary coil of the solenoid flow control valve was used successfully for the first three orbit-raising operations. During the fourth orbit-raising operations  today, the redundancies built-in for the propulsion system were exercised namely energising  of the primary and redundant coils of the solenoid flow control valve of 440 Newton Liquid Engine.