Failures and interfaces

The failure record holds 54 sourced entries from 2017 to 2027: 48 with a named mechanism and 6 that record an outcome without a published cause. The interface matrix holds 66 boundaries between twelve subsystems, 37 of them high criticality. Together they describe the same thing from two directions: a failure is an interface that was not managed, and an interface is a place where one subsystem’s change becomes another’s redesign. The failure counts measure how often a mechanism gets published, not how often it happens.

The failure record

Of the 54 entries, 51 carry a primary grade and 3 a secondary one. The zero in the dust row is a finding about publication, not about dust: dust is a known hazard with no written post-mortem behind it S-URC-ADVICE.

What the classes cost

The yearly totals run 994, 1120, 1051, 450 and 1350 for 2022 to 2026. A team that zeroes Equipment Servicing also zeroes Delivery 44 % of the time, 2.9 times the base rate, and Autonomy 85 % of the time, 2.1 times the base rate. That is the signature of one rover-level failure taking several missions down, not of three independent misfortunes.

The exceptions matter. Of the 67 Autonomy zeros, 58 % are isolated: the rover worked everywhere else and could not complete the autonomous task. Only 11 % of Equipment Servicing zeros are isolated. Autonomy is therefore two problems in one column, a capability gap that is the largest persistent loss in the field and a rover-level fault that shows up alongside a mechanical failure.

The interface matrix

The twelve subsystems are joined by 66 interfaces, and every pair has at least one. Criticality is applied mechanically: a boundary is high if a change on one side forces a redesign, a re-test or a re-freeze on the other, or if a failure there alone loses at least 10 mission points or breaches a rule.

Three features carry most of the warning. The arm and compute are the most coupled subsystems, so deferring either decision is expensive. Every power interface except the thermal one is electrical, and the E-stop rule requires all power draw to cease on one button, which touches power, compute, communications, the arm and the astronaut interface at once S-URC27-RULES §2.a.v. Delivery has a single high interface, the arm’s 5 kg grasp, because it re-uses the existing boundaries rather than adding a new one.

The documented interfaces

The table lists the 41 interfaces that carry a named risk and a documentary trail; the matrix has 66 cells in total, and the remaining ones are recorded in the interfaces analysis.

The values on this page