FDIR - Match the observable with the failure

If you could eat one type of space food for the rest of your life, which would you choose?

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Match the Observable with one of the following failure:

Degraded data quality from onboard instruments (e.g. images are corrupted)

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• Propulsion system malfunction

• Transmitter failure

• Radiation damage to data handling electronics

• Thermal control system failure

Answer explanation

Detection:
How can the satellite detect that its data quality has degraded?

Answer: The satellite’s data processing system analyses the quality of data being transmitted from instruments (e.g. signal-to-noise ratio). The ground segment can also analyse the data overtime and flag if the data is below acceptable quality thresholds.

Match the Observable with the Failure:

Drop in power output from solar panels​ ​ ​ ​ ​

• Solar panel degradation
• heat dissipation issue

• radiation damage to data handling
• Thermal control system failure
• Solar panel damage (micrometeoroid impact)

Answer explanation

Detection:
How would the satellite detect a drop in power generation from its solar panels?

•Answer: The satellite continuously monitors power levels using voltage and current sensors. A significant drop in these values below expected thresholds would trigger a fault detection.

Match the Observable with the Failure: Loss of signal (communication interruption) with ground station​ ​ ​ ​ ​

• battery DoD incorrect

• Power regulation failure
• Radiation damage to data handling
• corrupted images
• Transmitter failure

Answer explanation

Detection:
How can the satellite detect a loss of communication with the ground station?

Answer: The satellite can monitor the frequency of TC received from ground, but most of the time the ground station is the one detecting that no TM are arriving from the satellite.

Match the Observable with the Failure: Failure to execute orbital correction maneuver ​ ​ ​ ​ ​

• propulsion system malfunction
• valve stuck open

• valve stuck close

• thermal control system failure
• transmitter failure

Answer explanation

•Detection: How would the satellite detect that it failed to perform an orbital correction maneuver?

•Answer: The satellite’s navigation system monitors its velocity and trajectory using sensors like accelerometers and GNSS. If the expected velocity change after a maneuver is not detected, it triggers a fault detection. Telemetry monitoring is also crucial, as it helps identify anomalies in thruster performance, including unexpected drops in pressure, unusual temperature variations, or  irregularities in the thrust produced. Additionally, the ability to execute orbital maneuver and maintain attitude control should be regularly assessed. If multiple thrusters are available, their performance can be compared to identify potential faults in any single thruster.

​ Parameter monitoring (PMON)​ , what does it do? ​ ​ ​

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• checks the functionality of a system or subsystem
• criteria can include expected value checks
• criteria can include expected limit checks
• monitors telemetry to collect anomalies
• monitors to ensure redundant chain functions

Match the Observable with the Failure: Increased temperature in one of the thermal area​ ​ ​ ​ ​ ​

• Thermal control system failure
• heat dissipation issue
• radiation damaged of data handling
• power management failure
• power regulation failure

Answer explanation

Detection:
How would the satellite detect that a subsystem's temperature is rising beyond safe limits?

•Answer: Temperature sensors monitor each thermal area. If the temperature exceeds a predefined safe threshold, a fault detection alarm is triggered.

One of your 4 reaction wheels is not operating at its expected rotational speed. Which detection level matches what recovery in this case?

• D0 internally

  with

  R0 Internally

• D3 software

  with

  R2 Functional chain

• D1 unit

  with

  R2 Functional chain

• D4 Satellite

  with R4 Safe mode

Answer explanation

Answer: D1 – R2

There are cases in which detection at unit level cannot be recovered by reconfiguration of that unit.
The typical cases are units that do not follow the one-for-one redundancy.
Example: failing RW is generally not replaced by another unit, but results in a particular mode of control based on three actuators instead of four.

Now, since you became a FDIR expert, is FDIR a bottom up or top down discipline?

• Bottom-up

• Top-down

• Transversal across all systems

• Both bottom up and top down

• It's a mess....