Spacecraft Autonomous Safing Sequence

Inject a Fault

Limit-Checking Logic

Debounce hold time 3.0 s

Manual override OFF

Vehicle State

NOMINAL

Bus temp

20.0 °C

Battery bus

28.0 V

Tumble rate

0.0 °/s

Time in violation

0.0 s

FDIR Event Log

[T+0.0s] Systems nominal.

How it works

Real flight software watches every telemetry point against pre-launch upper/lower limit values. A single sample outside limits is not enough to act on — sensor noise and transients would trigger false alarms constantly — so the check requires the value to stay out of limits for a debounce hold time τ before it counts as a real violation:

violating(t) = |x(t) − x_nominal| > L_limit
trigger      = violating held continuously for ≥ τ  (τ here: 0–8 s)

Once the hold timer expires, the Fault Detection, Isolation & Recovery (FDIR) logic autonomously commands the safing sequence: the vehicle slews to a fixed sun-pointing safe attitude (maximizes solar-array power, the one resource everything else depends on), sheds every non-essential load, and switches the low-gain omni antenna for a robust — if low-bandwidth — link so ground control can diagnose the fault without racing the clock. This is the same three-stage reflex used on essentially every uncrewed spacecraft when contact with ground control is not guaranteed in real time.

Bus Overheat / Undervoltage / Attitude Tumble — inject one telemetry excursion at a time; the readout turns amber while it is outside limits but still within the hold window, then red once the hold timer expires and safing fires.
Debounce hold time — shorten it to see safing fire almost instantly on any blip (realistic false-alarm risk); lengthen it to see a real fault run longer before the vehicle protects itself.
Manual override — simulates a ground-commanded inhibit: limit checking still runs and logs violations, but autonomous safing is suppressed, exactly as an operator can do during a planned high-risk maneuver.

Sun vector Solar array normal Nominal / Safe attitude

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.