1. The martian rule

Andy Weir’s The Martian is essentially a long argument with reality. Mark Watney has a problem, he guesses a solution, he tests it, and reality tells him whether his guess was good. The most memorable moments are not the triumphs; they are the moments when a test reveals that the plan was wrong. The book respects the reader by making the tests fair.

This entry applies the same rule to the desktop programme. After three hundred and twenty-four ledger entries, what is the next claim that most deserves a fair test?

2. The field of claims

The ledger contains many claims at different scales:

  • Mechanical: the square-cell, rack-based architecture is serviceable in orbit.
  • Thermal: a passively cooled rack can dissipate the heat of a high-power compute board.
  • Power: a modest solar array can keep a >500 W desktop alive in LEO.
  • Operations: a weak federation of cells can run without a single point of failure.
  • Economic: a keeper service can pay for part of the desktop programme.
  • Regulatory: the programme can obtain the licenses it needs.

These claims are connected. The power claim assumes the thermal claim. The economic claim assumes the operational claim. The regulatory claim assumes the political claim.

3. The selection rule

The next claim to test is not the most important one. It is the one whose failure would teach the most while costing the least. Popper would call it the most falsifiable high-leverage claim.

Applying that rule, the strongest candidate is the attachment interface: the idea that a cell can be mechanically and electrically connected to a rack in a way that allows robotic replacement. This claim sits at the center of almost every other claim. If it fails, the modular architecture fails. If it holds, many other claims become easier to test.

4. Why this claim first

The attachment interface is a good first claim for three reasons:

  • It is concrete. A test can be built on the ground with real hardware.
  • It is separable. It does not require a launch or a full satellite.
  • It is informative. Success or failure both tell you what to do next.

A ground test of robotic insertion, electrical mating, and thermal contact would either retire a major risk or expose a hidden problem early. Both outcomes are valuable.

5. What the test would look like

The test does not need to be exotic. A single-axis actuator, a mock rack, a mock cell, and a set of repeated mate-and-demate cycles would answer most of the important questions. The measurements would include alignment tolerance, insertion force, contact resistance, thermal resistance, and repeatability after many cycles.

This is the kind of test an engineer would run in a lab on a Friday and think about all weekend.

6. What this changes

  • The next claim to test is the attachment interface, not a full system.
  • The criterion is falsifiability and leverage, not importance alone.
  • The test can be done on the ground, cheaply and quickly.
  • This claim becomes the focus of the next two entries.