1. When the lights do not go out cleanly

Neal Stephenson’s Seveneves returns as the recalled work because the cloud ark’s power failures are never a simple switch flip. They are sequences: a sag, a trip, a decision about which loads to keep, and a slow restart where every subsystem wants power at once. The desktop’s power failures will look the same.

This entry explains why the power failure and brownout recovery test matters.

2. Why the power system needs its own fault injection

The power reading arc established that the desktop should use a solar-battery architecture with scalable distribution and protected power electronics. The autonomous power budgeting arc decided that the platform should shed load and defer tasks when energy is constrained. Both are design claims. The brownout recovery test is the experiment that validates them.

Without brownout testing, the desktop might discover these problems only after launch:

  • A voltage sag resets the flight computer but leaves power switches in an unknown state.
  • A battery cell fault triggers a protection shutdown, removing power from critical heaters.
  • A solar array string fails, and the platform does not reduce load fast enough to avoid collapse.
  • Recovery from a brownout causes inrush current that trips the battery again.
  • A load-shedding action corrupts a customer payload’s state because the shutdown was not graceful.

3. The failures that only appear when power is disturbed

Power fault injection exposes behaviors that do not appear in nominal testing:

  • A watchdog fires during a sag but the bootloader tries to restart too many cells at once.
  • A non-volatile storage write is interrupted by power loss, leaving the filesystem inconsistent.
  • A thermal heater is shed just as the platform enters eclipse; temperature drops faster than expected.
  • A communications radio browns out and loses lock, preventing ground from diagnosing the event.
  • The power manager’s own telemetry goes silent because it was powered from the channel that failed.

4. What this test must cover

The power failure and brownout recovery test must exercise:

  • Voltage sags and surges on the main bus.
  • Battery depletion and low-voltage disconnect.
  • Loss of one or more solar array strings.
  • Sudden loss and return of a major load.
  • Load-shedding execution under time pressure.
  • Controlled shutdown and sequenced restart.
  • Recovery of persistent state after an unexpected power loss.

The goal is to prove that the platform can detect a power threat, protect critical functions, and recover cleanly when power returns.

5. What this changes

  • Power failure and brownout recovery testing is identified as the next qualification step for the desktop.
  • The test must verify survival and recovery, not just detection.
  • The next entry will define the test matrix.