1. The book that survived the silence

Walter M. Miller Jr.’s A Canticle for Leibowitz returns as the recalled work because its monks preserve knowledge through long periods when no one else is listening. Autonomy on the desktop is similar: the platform must keep operating through ground-silence intervals, preserving enough state and function that normal service can resume when contact returns.

Entries 565 through 567 read about spacecraft autonomy architectures, fault detection/isolation/recovery, and what they mean for the desktop. This entry closes the arc.

2. What was learned

The autonomy literature gives the desktop four constraints:

  • Autonomy is layered. Function-level autonomy handles local loops; system-level autonomy coordinates across subsystems.
  • FDIR is the backbone. Without detection, isolation, and recovery, autonomy is just unmonitored freedom.
  • Ground-off-the-loop operation is achievable but bounded. It requires stored procedures, health monitoring, and safe-mode design.
  • Architecture matters. Centralized, distributed, and hierarchical FDIR each have trade-offs; the desktop’s modular structure favors a hierarchical approach.

3. What was decided

The desktop will adopt a hierarchical autonomy architecture with event-driven FDIR. This means:

  • Each cell or attachment runs local fault detection and first-level recovery.
  • The platform supervisor monitors cell health, resolves conflicts, and triggers system-wide reconfigurations.
  • Stored command sequences and OBCP-style event procedures handle routine operations during ground outages.
  • Safe mode preserves power, thermal, attitude, and communications readiness, and is reversible.
  • Autonomy horizons will be specified in orbits, not hours, because the desktop’s schedule is dominated by LEO pass geometry.

4. Interaction with earlier arcs

The autonomy arc connects directly to the fault recovery test arc, the network reconfiguration test arc, the power distribution test arc, and the compute migration wondering arc. It also sets up the predictive maintenance wondering arc that comes next.

5. What remains open

The exact autonomy horizon, the list of fault scenarios, and the choice between rule-based and model-based diagnostics depend on the final desktop configuration and the operational concept. The reading arc has set the strategy; detailed procedure writing comes later.

6. What this changes

  • The spacecraft autonomy reading arc is closed.
  • The desktop inherits explicit hierarchical autonomy and FDIR requirements.
  • The next arc will wonder about autonomous health management and predictive maintenance.