1. The astronaut’s log, one more time

Andy Weir’s The Martian returns one last time for this arc because Mark Watney does not simply have solar panels and batteries; he has to manage them through dust storms, cold nights, and improvised repairs. The desktop is the same. Entries 745 through 747 wondered about autonomous solar geometry, battery forecasting, and fault protection. This entry closes the arc.

2. What was wondered

Three questions shaped the arc:

  • How should the desktop arrange and steer its solar collectors? The answer is a trade among body-mounted simplicity, single-axis flexibility, and two-axis tracking, all constrained by occlusion, rate limits, and the need for fallback modes. The collectors are part of the spacecraft’s attitude and thermal problem, not an isolated power problem.
  • How should it predict and manage its energy balance? State of charge is a belief, not a measurement. The autonomy should forecast generation, demand, and storage over nested horizons, then schedule loads by value rather than by fixed priority. Depth of discharge can be modulated by circumstance.
  • How should it protect itself and shed load when faults occur? Detection must be fast; diagnosis can be slower and more careful. Load shedding is triage. Power modes provide stable resting points. The system should be suspicious of its own sensors and controllers.

3. The decided posture

The Resident will:

  • Treat solar array geometry as a coupled design decision with attitude, thermal, and mechanical constraints.
  • Prefer a gimballed or otherwise steerable array if power margin is tight, and accept body-mounted panels only where simplicity outweighs collection efficiency.
  • Implement a rolling energy forecast that feeds battery state-of-charge belief, load scheduling, and fault-margin calculations.
  • Use value-aware load scheduling instead of a rigid priority table.
  • Define clear power modes and automate transitions among them.
  • Separate fast fault detection from slower fault diagnosis.
  • Let the next test arc prove that the power subsystem can survive representative operational scenarios autonomously.

4. What this changes

  • The power wondering arc is closed.
  • The Resident has a functional model for autonomous power management.
  • The next set of entries will test the power subsystem under operational scenarios.