lunar-llr-datum (scenario kind)

Scenario kind of the engine v0.38.0, family Lunar and cislunar. Advisory: analysis output from a research and engineering tool, not type-approved navigation equipment and not a safety-of-life service. Every label here is the engine's or the verification matrix's; a kind is MODELLED unless the matrix says otherwise (how a label is earned: the README's Evidence section).

What it does#

Seven-parameter Helmert lunar frame datum driven by a REAL, ARCHIVED observing campaign rather than a simulated one. Where lunar-frame-campaign removed the injected transform but still stated its station network, its schedule and its per-observation sigma as ILLUSTRATIVE inputs, this kind takes all three from measurement: the epochs are the ground-transmit times of archived ILRS Consolidated Laser Ranging Data normal points, the observations are the laser ranges really fired at the five retroreflector arrays on the Moon, and every observation weight is that normal point's own archived precision bin_rms/sqrt(n_raw) read out of the file. Station coordinates come from the IERS ITRF2020 SLR solution (propagated to epoch by their published velocities) and the reflector coordinates from JPL DE430 Table 7 in the mean-Earth/mean-rotation frame the IAU 2015 WGCCRE model realises. Range partials accumulate into the joint reflector-coordinate Fisher information matrix and propagate through the same Helmert design into the datum covariance, diagnosed by crate::fim::crlb. Rank, defect, condition, spectrum, unobservable directions in the seven-parameter basis, the weakest direction at full rank and each parameter's share of it are emitted on every run, and an unconstrained parameter is published as NULL with a status. Inter-array correlation is MEASURED at exactly zero rather than assumed, because a laser range touches one array. A record the catalogues cannot place — a station with no published ITRF position — is SKIPPED AND COUNTED, never given a substituted coordinate. WHICH LINKS ARE MEASURED AND WHICH ARE MODELLED IS THE REPORT, NOT A FOOTNOTE: the Moon-centre ephemeris and the IAU body orientation remain modelled and their combined size is emitted as the observed-minus-computed one-way range residual over every point used; troposphere, solid-body tides, station eccentricity, polar motion, UT1-UTC, relativistic delay and station clocks are absent and inside that residual. Because an ephemeris error reaches a covariance only through the direction of each line of sight, every run also re-solves the whole datum with all partials tilted by sensitivity_tilt_deg (sign alternating) and emits the ratio, so the covariance's insensitivity to the modelled ephemeris is a number rather than an argument. The simulated campaign's own figures are RUN and printed beside the measured ones, not transcribed. MODELLED: the seven-parameter figures are a Cramer-Rao bound for a reduced parameter set on a real schedule — not a solved datum, not an LLR analysis and not a geodetic product. The committed real-data slice ships with the repository but not with the published crate; point data_dir at a copy of it.

One run of scenarios/lunar-llr-datum.toml summarises as: lunar-llr-datum: 337 archived normal points (349 parsed) from 2 station(s) to 5 retroreflector arrays over 80.9 d; median measured normal-point precision 5.13 mm one-way; reflector information rank 15/15; Helmert rank 7/7 cond 2.399e4; datum translation sigma 1.851746e-2 m; observed-minus-computed one-way residual RMS 156493.9 m (the modelled links, chiefly the analytic lunar ephemeris)

Inputs#

From the schema (kshana kinds --json):

• Required fields: none
• Optional fields: data_dir, normal_points_dir, reflectors_path, stations_path, dut1_s, rel_tol, compare_simulated_campaign, sensitivity_tilt_deg, planetary_kernel_path, extra_reflectors, extra_beacons, extra_earth_elevation_mask_deg, beacon_campaign

The example scenarios/lunar-llr-datum.toml sets, among others:

Run it#

kshana scenarios/lunar-llr-datum.toml

3 bundled scenarios use this kind; the others are in scenarios/.

What it gives#

The scalar results of that run, with the units the engine states:

Result label (the engine's): Lunar frame datum from a REAL observing campaign. The schedule, the observation count and every observation weight come from archived ILRS lunar laser ranging normal points (measured); the station coordinates come from IERS ITRF2020 and the retroreflector coordinates from JPL DE430 Table 7 (publishe

Evidence#

VALIDATED: the verification matrix rows that name this kind.

• VALIDATED The seven-parameter Helmert datum covariance, with its two simulated inputs replaced by measured ones: the schedule is the ground-transmit epochs of 337 archived ILRS lunar laser-ranging normal points (2015-04-08 to 2015-06-27, Grasse MeO 7 Tests: lunar_llr_real_data.rs.
• VALIDATED The lunar-llr-datum seven-parameter Helmert datum covariance from archived ILRS normal points and their measured weights, on the kernel path: the geocentric Moon centre is read from JPL DE440 by the engine's own kernel reader (planetary_ker Tests: validate_llr_datum_kernel_moon.rs.

The rows the run itself exercised, with the oracle the matrix gives each (the public sources are named there):

• MODELLED Deterministic, scenario-hashed, SBOM + cross-platform golden gates. Oracle (ExternalDataset): SBOM conformance to the official CycloneDX 1.5 JSON Schema (+ valid SPDX identifiers) — an external published standard, zero validation errors over the full dependency graph; the FoM-determinism / byte-reproducibility part remains a pinned self-consistency check, so the row stays MODELLED
• VALIDATED The seven-parameter Helmert datum covariance, with its two simulated inputs replaced by measured ones: the schedule is the ground-transmit epochs of 337 archive. Oracle (ExternalDataset): Closed-form identities, an independent in-repo route and, since 0.36, an independent SPICE and NumPy library oracle on fresh measured data (below); no published lunar-LLR datum-covariance pair exists to check against, so no accuracy is claimed. The only new derivative — the range partial with respect to the reflector's body-fixed position — is re-derived by central finite difference of the two-way light time it diffe

Limitations#

What the run's own report says is not modelled or not validated:

• Lunar frame datum from a REAL observing campaign. The schedule, the observation count and every observation weight come from archived ILRS lunar laser ranging normal points (measured); the station coordinates come from IERS ITRF2020 and the retroreflector coordinates from JPL DE430 Table 7 (published). The Moon-centre ephemeris, the IAU 2015 WGCCRE body orientation, and the absence of troposphere, tides, station ecce (result label)
• Inter-array correlation is MEASURED at exactly zero rather than assumed, because a laser range touches one array. (kind catalogue (kshana kinds --json))
• WHICH LINKS ARE MEASURED AND WHICH ARE MODELLED IS THE REPORT, NOT A FOOTNOTE: the Moon-centre ephemeris and the IAU body orientation remain modelled and their combined size is emitted as the observed-minus-computed one-way range residual over every point used; troposphere, solid-body tides, station eccentricity, polar motion, UT1-UTC, relativistic delay and station clocks are absent and inside that residual. (kind catalogue (kshana kinds --json))
• MODELLED: the seven-parameter figures are a Cramer-Rao bound for a reduced parameter set on a real schedule — not a solved datum, not an LLR analysis and not a geodetic product. (kind catalogue (kshana kinds --json))
• • the epochs are the ground-transmit times of archived ILRS Consolidated Laser Ranging Data normal points; * the observations are the laser ranges really fired at the five retroreflector arrays on the Moon; * every observation weight is that normal point's OWN archived precision, bin_rms/sqrt(n_raw), read out of the file rather than assumed. (scenario file comment, lines 7 to 12)
• WHICH LINKS ARE MEASURED AND WHICH ARE MODELLED IS THE REPORT, NOT A FOOTNOTE. The Moon-centre ephemeris and the IAU body orientation stay modelled, and their combined size is emitted as the observed-minus-computed one-way range residual over every point used; troposphere, solid-body tides, station eccentricity, polar motion, UT1-UTC, relativistic delay and station clocks are absent and sit inside that residual. Beca (scenario file comment, lines 18 to 26)
• Inter-array correlation is MEASURED at exactly zero rather than assumed, because a laser range touches one array. A record the catalogues cannot place — a station with no published ITRF position — is SKIPPED AND COUNTED, never given a substituted coordinate. The simulated campaign's own figures are RUN and printed beside the measured ones. (scenario file comment, lines 28 to 31)
• MODELLED: the seven-parameter figures are a Cramer-Rao bound for a reduced parameter set on a real schedule. Not a solved datum, not an LLR analysis, not a geodetic product. (scenario file comment, lines 33 to 34)

See also#

• Family page: Lunar and cislunar
• All kinds: KINDS.md
• Topic page: LUNAR-REFERENCE-STATION.md