Supplementary Orbit Raising Manoeuvre Planned for Mars Orbiter Spacecraft
In the fourth orbit-raising operation conducted this morning (Nov 11,
2013), the apogee (farthest point to Earth) of Mars Orbiter Spacecraft was
raised from 71,623 km to 78,276 km by imparting an incremental velocity of
35 metres/second (as against 130 metres/second originally planned to
raise apogee to about 100,000 [1 lakh] km). The spacecraft is in normal
health. A supplementary orbit-raising operation is planned tomorrow
(November 12, 2013) at 0500 hrs IST to raise the apogee to nearly 1 lakh
km.
During the orbit-raising operations conducted since November 7, 2013, ISRO
has been testing and exercising the autonomy functions progressively, that
are essential for Trans-Mars Injection (TMI) and Mars Orbit Insertion
(MOI).
During the first three orbit-raising operations, the prime and redundant
chains of gyros, accelerometers, 22 Newton attitude control thrusters,
attitude and orbit control electronics as well as the associated logics
for their fault detection isolation, and reconfiguration have been
exercised successfully. 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 held today (November 11, 2013),
the redundancies built-in for the propulsion system were exercised,
namely, (a) energising the primary and redundant coils of the solenoid
flow control valve of 440 Newton Liquid Engine and (b) logic for thrust
augmentation by the attitude control thrusters, when needed. However, when
both primary and redundant coils were energised together, as one of the
planned modes, the flow to the Liquid Engine stopped. The thrust level
augmentation logic, as expected, came in and the operation continued using
the attitude control thrusters. This sequence resulted in reduction of the
incremental velocity.
While this parallel mode of operating the two coils is not possible for
subsequent operations, they could be operated independently in sequence.
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(Release ID :100503)