EIR-OPS-028: High Rotation Rate Fault Analysis


Objective

To assess the status of the spacecraft’s ADCS systems after a high rotation rate event.


Introduction

Using this procedure, the Operator will be guided through some considerations to keep in mind when assessing the cause of the high rotation rate event and when working towards resuming nominal operations.

Note

The analysis to be carried out by the team is very dependent on the findings as well as what data was successfully downlinked. Therefore, rather than a strict set of instructions, this procedure instead provides information to help guide the Operator in their analyses. Also note that in addition to any data downlinked by the UCD GS, data obtained via the amateur radio community may also be used to support the analysis/findings.


Procedure

This procedure contains the following sub-procedures:

A. Enabling Loggers
B. Initial Considerations
C. Remedying the Situation

A. Enabling Loggers

A.1.

  • If the ADCSDebug Logger is thought to be disabled, the Operator should now follow Section A of the EIR-OPS-008: ADCS Mode Change procedure to enable it.



B. Initial Considerations

B.1.

  • With the ADCS Engineer, the Operators should now review data downlinked from the spacecraft. In particular review any downlinked HK, PASCAL, ADCSHK, and if available, ADCSDebug data to assess:

    • What mode/state was the ADCS operating in prior to the Safe Mode trigger?

    • When did the spin rate of the satellite begin to increase? How fast did it increase? Did it stop, or is it still increasing?

    • What was the behaviour of the MTQs prior to/during this spin rate increase? Is there evidence that any of the MTQs caused this increase in rotation?

    • Do all of the ADCS sensors agree that the satellite was spinning at an increased rate during the time period in question?

    • etc.


…



C. Remedying the Situation

C.1.

  • If the Operator next wishes to perform some ADCS operations to remedy the current situation and resume nominal operations, the Operator should note:

    • Safe Mode should be exited, using the EIR-OPS-007: Operational Mode Change procedure, before attempting to perform any ADCS Operations to slow the spin rate of the satellite.

    • If the satellite’s spin rate still exceeds the Safe Mode trigger limit, the Operator may first need to following the EIR-OPS-035: Configure the FDIR Systems procedure to slightly decrease the rawGyroRateTotalSqrd limit and allow Safe Mode to be stably exited. Alternatively, TimeAction functionality can be set-up to temporarily disable monitor checks of the rawGyroRateTotalSqrd parameter. If the latter is desired, the Software Engineer should now be contacted for assistance.

    • The FSS was powered off on entry to Safe Mode and so it is disabled at this time. Therefore, the Operator should enable the FSS before proceeding with any ADCS Operations that require its data.


…


END OF PROCEDURE