Gyroscope difts

This display concerns two aspects of the gyroscope drifts, the evolution of the zero point (shown below) and the evolution over an orbit after removal of the zero point (second chart).

The evolution of the zero points shows very different behaviours for the four gyroscopes that have been active. No clear links with temperature seem to exist, but the behaviour of gyroscopes 1 and 2 may reflect the general out gassing of the spacecraft.

Gyro drift zero point evolution

After correcting for the reference drift there is still a variation of the drift as a function of orbital phase. Here the modulation as a function of the rotation phase has also been corrected for. What remains are the temperature variations caused by the eclipses, affecting the satellite for example around day 400 and day 1000. Also noticeable is the breakdown of gyroscope 1 towards the end of the mission.

Gyro drift orbital phase map