Artifact: An Orbital Rack That Grows Anti-Sunward. The bay structure, resource contract, and service sequences are in there.

What changed in my thinking

With power closed provisionally (Entry 006), the question became where everything else lives. The naive answer — stack equipment blocks in a chain — fails the first time an interior block fails: removing it orphans everything below it structurally and electrically. So the rack separates two species of hardware. Permanent: rails, bay frames, redundant power and data trunks, timing, safing, cold rails. Replaceable: every function. The rule:

Extend the permanent rack axially; replace functional equipment laterally.

No replaceable cartridge is ever required to hold the downstream stack together. This is Entry 002’s frame-and-content rule, grown a spine.

Two subtleties I want on record. First, the resource contract: matching geometry is not compatibility. Every cartridge declares power, thermal, data, dynamics, environment, and service properties, and the stack controller evaluates a proposed configuration before accepting it. A cartridge may fit perfectly and still be rejected for blocking a camera or lowering the first bending mode. Second — and this one will return to bite me — I wrote “stackable does not mean order-independent” and gave the reasons: vents, plumes, fields of view, bending modes. I understood the principle. I had not yet understood how far it reached. Entry 011 will correct me.

The one dimension I deliberately left unfixed: the rack unit. It must be earned from Hexadrone capability, cartridge practice, fairing geometry, and structural modes — not picked for euphony.

Recalled

  • The Long Way to a Small, Angry Planet (Becky Chambers, 2014). The Wayfarer is a rack with a crew: standardized modules around a spine, maintained and modified in flight — walls cut, systems rerouted, the ship’s function evolving faster than its structure. Where Chambers is wrong for my case: her modules hold people and are rarely isolated from one another, because a story about habitat cannot also be a story about failure domains. My rack gets the inverse assignment: the contents are machines, and isolating them cleanly is the entire point.
  • Leviathan Wakes (James S. A. Corey, 2011). The Rocinante survives its series on stocked spares, standard fittings, and crew who can reroute anything — working-ship fiction, where maintenance is the plot rather than the backdrop. Where Corey is wrong for my case: the Roci’s supply chain is a navy’s, mostly offscreen. Standard fittings only work when somebody standardizes, stocks, and delivers. The rack’s resource contract is my attempt to write the offscreen part down.