Space Digital Twin

make space-digital-twin-check is the bounded Phase S4 gate for deterministic

mission digital twin evidence. It validates state snapshots, replay streams,

execution modes, XTCE standards exchange rows, and trace links to

requirements, hazards, and evidence bundle identifiers.

This is local evidence for a standards-facing twin bridge. It is not a claim

that a mission ground system has accepted the exported metadata or that HIL has

run on physical hardware.

Evidence Files

• space/digital-twin-snapshots.tsv records versioned state snapshot and

timeline fixtures with SHA-256 hashes.

• space/digital-twin-replay-streams.tsv records telemetry and command stream

fixtures, simulation-time policy, deterministic seed, and expected timeline

hash.

• space/digital-twin-modes.tsv separates strict deterministic replay, SIL,

HIL, Monte Carlo, operations shadow, and what-if modes.

• space/digital-twin-standards.tsv records the XTCE export/import bridge,

source hash, version, and limitations.

• space/digital-twin-links.tsv links twin state, telemetry schemas,

requirements, hazards, and evidence bundle identifiers.

Requirements

• REQ-S4-001: simulation time is explicit and is not confused with wall-clock

time.

• REQ-S4-002: recorded telemetry replay produces a comparable, hashable state

timeline.

• REQ-S4-003: distributed twin execution distinguishes deterministic mode

from real-time mode.

• REQ-S4-004: standards export/import records version, schema, source hash,

and limitations.

Mode Boundary

Strict deterministic replay, SIL, Monte Carlo, and what-if modes are accepted

local evidence lanes. Operations shadow can observe real-time inputs but still

records input and state hashes. HIL is physical-gated: the mode is defined,

but no physical HIL claim is accepted until physical hardware evidence passes.

Failure Behavior

The checker emits stable JSON diagnostics:

SPACE_TWIN_MISSING   required table, fixture, document, or evidence file is missing
SPACE_TWIN_SCHEMA    a digital-twin TSV has the wrong header
SPACE_TWIN_FIXTURE   JSON fixtures are malformed
SPACE_TWIN_EVIDENCE  a referenced source symbol or evidence file is missing
SPACE_TWIN_MODE      mode rows are missing or violate deterministic policy
SPACE_TWIN_SNAPSHOT  snapshot rows or fixture schemas are invalid
SPACE_TWIN_REPLAY    replay stream rows are invalid
SPACE_TWIN_TIME      simulation time is missing where required
SPACE_TWIN_STANDARD  standards bridge rows are invalid
SPACE_TWIN_LINK      trace link rows are invalid
SPACE_TWIN_REQ       S4 requirement trace rows are missing or invalid
SPACE_TWIN_DOC       public documentation is missing required S4 terms
SPACE_TWIN_HASH      recorded hashes do not match source-owned fixtures

Operational Boundary

The S4 gate proves deterministic local replay and XTCE-compatible exchange

evidence for current 0x0 surfaces. A mission still has to validate its own

ground-system import, hardware timing, operational data feeds, and external

assurance review.