Appearance
Earth Orientation Parameters Supply Chain
EGV Level: 3 — Global · Geometric | Date: September 2026 | Version: 5.1
Reference: EGV White Paper V7.0 (GGOS, January 2026) · Guiding Principles v4.6 · 1st Joint Development Plan (JDP)
Major revisions:
- v5.1 — Replaced the raw
data/project/agy_research_findings_function_validation.mdfilename reference in the v5.0 entry below with a working link to the hosted portal (un-ggce.merchantsofmalta.com). Part of a sweep across the whole deliverable set for the same issue, per the user's request. - v3.6 — Renamed the per-capability "Phase 1/2/3" priority tag to "Horizon 1/2/3", matching the framework used throughout Work Assignment 1b.
- v3.8 — Added the Capability Evidence Trail (confirmed / asserted / considered / queued), extending the method piloted on the Satellite Orbits annex.
- v4.1 — Resolved a contradiction between the Overview (describing two EOP product tracks) and Tier 3/4 (describing three) — confirmed three is correct, matching what the workflow tiers document.
- v4.2 — Incorporated previously-unaddressed Russia-Ukraine and NASA GSFC workforce/shutdown evidence into the Tier 0–3 narrative and Evidence Trail (Confirmed count 21 → 17, Considered-and-not-asserted 0 → 4).
- v4.3 — Corrected a misidentification of the three Global Data Centres (BKG had been listed alongside CDDIS and IGN as a GDC; the third GDC is SIO).
- v5.0 — Converted from the retired five-tier structure to nine real functions (F1...F9, with F7 split into two parallel, non-substitutable tracks F7a/F7b), following Work Assignment 2 v5.0's precedent and its own external validation pass (full findings). Tier 0 becomes F1 (Space Geodetic Multi-Technique Observation) unchanged in scope. Tier 1 splits three ways: first-mile telemetry becomes F2, archiving becomes F3, and the VLBI correlation narrative embedded in its prose moves to F4 together with the Geodetic Software and Tools capability that had been sitting in old Tier 2's table — the prior bundling obscured that correlation is a distinct, severely constrained computing bottleneck, not a footnote inside "archiving." Tier 2 splits into F5 (VLBI Technique Analysis, UT1/CPO — carrying VLBI Data Processing and Analysis plus Knowledge Management) and F6 (Satellite Geodetic Analysis, PM/LOD — carrying GNSS Data Processing and Analysis). Tier 3 splits into F7a (Rapid Combination & Prediction, Bulletin A, USNO) and F7b (Definitive Combination, Bulletin B/C04, SYRTE) — correcting a framing this document previously carried, that the combination function "spans two jurisdictions overall... clearing the Minimum Capability Target's 2-jurisdiction threshold." Each track is in fact an independently single-institution, single-jurisdiction operation; treating them as one two-jurisdiction function understated the exposure of each. F8 (Product Quality Assurance) is newly named as its own function, carrying no currently-scored capability — a genuine coverage gap this document did not previously surface, not silently absorbed into "combination" or "validation." Tier 4 becomes F9 (Dissemination & User Access). Matching Work Assignment 2 v4.0/v6.0's precedent, removed the retired Tier Risk Score / PPTD Gap × Step Criticality apparatus and the per-capability Horizon 1/2/3 tag throughout — PPTD scores are shown as descriptive context only. Corrected the PPTD averaging convention to exclude not-applicable dimensions rather than scoring them 0 (matching Work Assignment 1b v7.0 Annex A.2): Risk Management's average moves from 0.50 to 1.00 (Technology and Data excluded), Performance Management from 1.00 to 2.00 (same two dimensions excluded), and Disaster Recovery and Supply Chain Continuity from 1.25 to 1.67 (Data excluded) — the same three corrections already applied to the Satellite Orbits annex, confirming these are shared-capability corrections that apply identically across products. Also carried forward Geodetic Services (2/2/2/2) into F9, which Work Assignment 2's own summary table for EOP currently omits (it lists only Disaster Recovery and Data Distribution for F9) — this annex's own Tier 4 table has always scored it, and the "21 of 58 capabilities" count this document has carried since v3.8 already included it; flagged for Work Assignment 2 to reconcile rather than silently dropped here.
Subsequent versions applied editorial and terminology consistency fixes only unless otherwise noted above.
PPTD (People, Process, Technology, Data) scores: State of Geodesy 2026 — A baseline maturity assessment (UN-GGCE, 16 March 2026)[^sog2026]
Audience
This document serves two readerships: (1) UN-GGCE leadership and technical counterparts already familiar with this engagement; and (2) UN-GGCE staff and Member State stakeholders new to this specific analysis. Readers new to the engagement should read this Purpose & Reading Guide; the function-by-function detail that follows supports the summary findings reported in the Work Assignment 2 and Work Assignment 3 reports.
Purpose & Reading Guide
This is one of five technical workflow descriptions supporting Work Assignment 2 of the UN-GGCE Global Geodesy Supply Chain Assessment (Terms of Reference 2). It maps, function by function, how Earth Orientation Parameters (EOP) is produced — the institutions involved, the capabilities each step depends on, and where the production chain is most exposed to failure.
Companion Documents
Readers new to this engagement should start with the Critical Product Mapping Report (Work Assignment 2), which maps this product's functions to capabilities, organisations and information artifacts at summary level; the Investment Prioritization and Risk Rubric (Work Assignment 1b), which defines the risk-scoring method; and the EGV Data Levels and Supply Chain Tiers appendix (Work Assignment 1 Appendix), which explains the underlying data-level structure this document's functions are keyed to.
Overview
Earth Orientation Parameters (EOP) is an Essential Geodetic Variable (EGV) that sits at Level 3 in the Global Geodetic Observing System (GGOS) EGV framework and constitutes the fundamental transformation parameters required to link the International Terrestrial Reference System (ITRS) to the International Celestial Reference System (ICRS). The EOP product suite encompasses four distinct sub-products: Celestial Pole Offset (CPO), Universal Time (UT1), Length of Day (LOD), and Polar Motion (PM). Together, these parameters define Earth's rotational behaviour in three dimensions and are essential for any application that requires the precise relationship between celestial and terrestrial coordinate systems.
The operational significance of EOP is pervasive across modern technological infrastructure. Space mission operations, deep space navigation, GPS orbit determination, precision timing, and very-long-baseline interferometry (VLBI) astrometry all depend on continuously updated EOP products. Because Earth's orientation fluctuates unpredictably on timescales ranging from sub-daily to multi-decadal, EOP must be measured and published across three distinct product series: a rapid daily series for near-real-time applications (such as spacecraft commanding and precision targeting), a final monthly series for historical consistency in geodetic reference frame computation, and a continuous long-term series for multi-decadal time series analysis.
EOP occupies a position of deep circular dependency within the geodetic supply chain. The final EOP series must be generated in a manner that is internally consistent with the International Terrestrial Reference Frame (ITRF) realisation, as the station positions and velocities underpinning the ITRF are themselves sensitive to the assumed EOP values applied during analysis. Similarly, the UT1 and CPO components are irreducibly linked to the International Celestial Reference Frame (ICRF), as they are determined by directly observing the angular relationship between the terrestrial and celestial frames using VLBI. This mutual dependency between EOP, ITRF, and ICRF means that degradation in any one of these pipelines propagates across all three. EOP is correspondingly dependent on the Level 2 EGVs Station Positions and Variations (Primary) and Satellite Orbits (Important), as defined in EGV White Paper V7.0.
Co-Produced EGVs
| EGV | Level | Mechanism |
|---|---|---|
| Global Reference Frames (ITRF) | 3 | Final EOP series is generated consistently with the ITRF |
| Global Reference Frames (ICRF) | 3 | UT1 and CPO determined by linking terrestrial VLBI to celestial radio sources |
Governance
| Institution | Role | Risk Level |
|---|---|---|
| International Earth Rotation and Reference Systems Service (IERS) EOP Product Center (SYRTE, the Observatoire de Paris's time/reference-systems unit) | Final combination and publication of official EOP series (Bulletin B, IERS C04) | Medium |
| IERS Rapid Service/Prediction Center (US Naval Observatory, USNO) | Daily ultra-rapid EOPs and near-term predictions (Bulletin A) | High |
| International VLBI Service (IVS) | VLBI observing program coordination and analysis | High |
| International GNSS Service (IGS) | Polar motion and LOD estimates via GNSS combination | Medium |
Supply Chain
Note on PPTD tables below: averages exclude not-applicable dimensions (marked N/A) rather than scoring them 0, per Work Assignment 1b v7.0 Annex A.2. Dimensionality (how many of the four dimensions apply) is shown alongside each average. ⚠ flags a capability whose corrected average falls below 2.5.
F1 — Space Geodetic Multi-Technique Observation
Data level: Basis → Level 1 EGV (Geodetic Observations) — raw signals and calibrated instrument data acquired by observatories and formatted to agreed community standards.
EOP production draws upon the same global network of ground observatories as the ITRF, but the relative contribution of each observing technique differs markedly depending on the EOP parameter in question. VLBI is the sole technique capable of directly and independently determining UT1, Earth's absolute rotation phase with respect to inertial space, and the Celestial Pole Offsets. No other current observing technique can recover UT1 without reference to an a priori EOP series, which makes the operational health of the global VLBI network a supply chain dependency of the highest order. To meet the latency requirements of the IERS Rapid Service at USNO, the IVS schedules dedicated "Intensive" VLBI sessions of approximately one hour duration each day, specifically designed to produce rapid UT1 estimates. These sessions involve a minimal subset of the global network — typically one or two baselines — and rely on high-speed e-VLBI data transfer to correlators.
Global Navigation Satellite System (GNSS), Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) provide high-frequency estimates of Polar Motion and Length of Day and are essential for the rapid and final EOP product tracks. The IGS global network of GNSS tracking observatories — coordinated across more than 500 sites — provides the most spatially dense and temporally continuous observations for PM and LOD, complemented by SLR and DORIS contributions for independent cross-validation and orbit determination. While these techniques collectively provide robust redundancy for PM and LOD, they cannot substitute for VLBI in the UT1 determination function.
This redundancy carries its own geopolitical exposure. In 2022, the International DORIS Service formally decommissioned two Russian DORIS stations (Krasnoyarsk and Yuzhno-Sakhalinsk), and a third, Badary, was shut down at Russia's request, producing what the IDS itself described as "a hole in DORIS coverage" across high-latitude Eurasia — a region already sparsely instrumented. CNES and IGN confirmed that closing the gap would require new agreements and new beacon deployments, work that "can take time" (Source: IDS DORIS News, May 2022, https://ids-doris.org/doris-news.html; IDS Workshop 2022, Chauveau, CLS, https://ids-doris.org/resources/presentations/ids-meetings/i03-2022-3654.html). A parallel review of Ukrainian GNSS station operability over the same period documents an approximately 10% reduction in active stations following the February 2022 invasion; the peer-reviewed source for that finding states directly that no primary evidence confirms a resulting impact on EOP computation (Source: Springer, Kinematics and Physics of Celestial Bodies, 2024).
The geographic distribution of the global VLBI network constitutes a structural vulnerability directly addressed by (Principle 1: Geographic Distribution for Technical Performance). Operational VLBI telescopes capable of participating in geodetic observing programs are heavily concentrated in the northern hemisphere, with poor coverage across the southern hemisphere, Africa, South-East Asia, and the Pacific. Many telescopes in the network are aging or operating under conditions of deferred maintenance. Restricted telecommunications bandwidth at remote sites delays data transmission, limiting the number of observatories that can participate effectively in e-VLBI-based rapid sessions. The capability maturity assessment scores Ground-Based Asset Management — the operational capability underpinning telescope availability and reliability — at 2.50, with every PPTD dimension clearing the Level 2 floor individually; it is a middling score, though still short of the Level 3+ maturity a genuinely resilient observatory layer would need.
One geopolitical stress event offers a contrasting data point for VLBI specifically. Through the same 2022 conflict period referenced above, the global VLBI network continued operating without confirmed disruption: the Russian VLBI stations at Zelenchukskaya, Badary, and Svetloe (operated by the Institute of Applied Astronomy) remained listed as active throughout 2022–2024, and no IVS-level network notice regarding Ukrainian or Russian stations was issued. No primary source confirms a direct impact on UT1 determination from the 2022 events (Source: UN-GGCE Reference Verification: Documented Supply Chain Disruptions and Risk Taxonomy, §4, "What Was NOT Disrupted"). Given VLBI's sole-technique status for UT1 described above, this is a meaningful point of resilience, though the evidentiary base for it is limited to a single event observed over a three-year window.
Risk: High — VLBI is the only technique capable of determining UT1; the global VLBI network is sparse, aging, and bandwidth-constrained for real-time data delivery. The single-technique dependency for UT1 is among the most acute structural vulnerabilities in the entire geodetic supply chain.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| VLBI Data Acquisition and Storage | 3.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
| GNSS Data Acquisition and Storage | 4.00 | 4.00 | 3.00 | 3.00 | 4 of 4 | 3.50 |
| SLR Data Acquisition and Storage | 2.00 | 4.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
| DORIS Data Acquisition and Storage | 4.00 | 4.00 | 4.00 | 4.00 | 4 of 4 | 4.00 |
| Ground-Based Asset Management | 3.00 | 2.00 | 2.00 | 3.00 | 4 of 4 | 2.50 |
| Equipment Calibration and Maintenance | 4.00 | 3.00 | 3.00 | N/A | 3 of 4 | 3.33 |
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F2 — First-Mile Telemetry & Transmission
Data level: Basis → Level 1 EGV transition. The transmission link between an observatory and its correlator or archiving destination is where a raw observation becomes a delivered, processable data stream.
For the VLBI Intensive sessions that underpin the IERS Rapid Service product, the data flow path is time-critical and operationally distinct from standard archiving. Observations must be transmitted via e-VLBI in near-real time from the participating observatories to IVS correlator facilities (F4). GNSS, SLR, and DORIS observations reach the Global Data Centres (F3) via automated push rather than a time-critical correlator path. Any latency introduced at this first-mile telemetry stage, whether due to bandwidth limitations at a remote observatory or network congestion, directly degrades the timeliness of the Rapid EOP product and, by extension, the accuracy of near-real-time space operations dependent upon it.
Risk: Medium — Latency at the first-mile telemetry stage directly impacts the Rapid EOP product; Network Operations' Technology dimension scores at the low end of the scale, reflecting the absence of automated failover and formal monitoring infrastructure at this layer.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Network Operations | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
(Source: State of Geodesy 2026)
F3 — Primary Archiving & Synchronization
Data level: Level 1 EGV (Geodetic Observations) — standardised observation files ingested to agreed formats.
Observation data from GNSS, SLR, and DORIS observatories flows into the established global data centre infrastructure — the three Global Data Centres (GDCs): the Crustal Dynamics Data Information System (CDDIS) hosted at NASA/GSFC, the Institut national de l'information géographique et forestière (IGN) archive in France, and the Scripps Institution of Oceanography (SIO) in the United States. These centres ingest data from contributing networks, apply initial quality screening, and make formatted observation files available to upstream analysis centres. The established multi-centre model provides a degree of archiving resilience; however, the capability maturity assessment records that CDDIS remains the single point of truth for certain geodetic datasets, with very limited geographic redundancy for data storage.
Risk: Medium — The continued dominance of CDDIS as the primary archive for VLBI data means this function also carries concentration risk against (Principle 2: Political Resilience and Distributed Operational Control).
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Data Quality Management | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Metadata Management | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Data Preservation | 2.00 | 2.00 | 2.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
(Source: State of Geodesy 2026)
F4 — VLBI Correlation & Fringe-Fitting
Data level: Level 1 (intermediate) — correlated interferometric observables (group delays), not yet a station-position or EOP solution.
The primary geodetic VLBI correlators — including the Washington Correlator at NASA/GSFC and the Bonn Correlator at the Max Planck Institut für Radioastronomie — receive the e-VLBI data streams transmitted at F2 and produce correlated output for immediate analysis at F5. The VLBI correlation process represents a structural throughput constraint in the EOP supply chain: correlation of VLBI data requires specialised hardware correlators and dedicated software stacks, and the global inventory of facilities capable of performing this function at geodetic quality is small. The concentration of correlator capacity at a limited number of centres — principally Washington and Bonn — means that any disruption to either facility would materially reduce the IVS's capacity to produce timely UT1 estimates for the Rapid Service. The capability maturity assessment records that VLBI correlation and analysis within the IVS correlator network relies significantly on in-kind institutional contributions, with inadequate dedicated funding creating latent fragility.
Risk: High — The VLBI correlation process requires specialised hardware and software. The global inventory of geodetic-quality correlators is small, concentrated at Washington (NASA/GSFC) and Bonn (MPIfR); any disruption or throughput constraint at either facility would directly delay the Rapid EOP product. No specific throughput incident has been recorded in the IVS technical archive reviewed for this assessment (IVS Biennial Reports 2019–2022, IVS Newsletters issues 53–70, IERS Rapid Service notices at USNO); the risk is structural at the primary facilities. The latent nature of this risk is compounded by the Washington Correlator's dependence on NASA/GSFC institutional continuity — the same jurisdictional vulnerability documented in the 2013 and 2018–2019 shutdowns that affected adjacent infrastructure at the same campus, and now compounded by DOGE-related workforce reductions that removed approximately 32% of NASA GSFC's civil servant workforce from February 2025 onward, and by the October–November 2025 U.S. government shutdown (42 days), during which GSFC buildings were emptied and staff recalled to clear facilities — a separate, still-unresolved risk. No throughput disruption attributable to either the workforce reductions or the 2025 shutdown has been found in the available technical record for this assessment. (IVS Biennial Reports 2019–2024: https://ivscc.gsfc.nasa.gov/publications/; DOGE workforce reductions: Space.com, Greenbelt News Review; October–November 2025 shutdown: NASA Shutdown Page; CNN, 4 November 2025.)
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Geodetic Software and Tools | 2.00 | 3.00 | 1.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
(Source: State of Geodesy 2026)
F5 — VLBI Technique Analysis (UT1/CPO)
Data level: Level 1 → Level 2 (intermediate) — uncombined VLBI-only EOP estimates (VLBI SINEX).
The International VLBI Service for Geodesy and Astrometry (IVS) coordinates the analysis of correlated VLBI data to produce UT1 and CPO estimates. IVS analysis centres apply specialised software to correlated VLBI data, estimating station positions, source coordinates, and EOP simultaneously through a least-squares adjustment. This is the sole technique-analysis pathway capable of producing UT1 and CPO — no other function in this workflow can substitute for it.
The knowledge concentration risk at this function is acute. The geodetic software employed by VLBI analysis centres is in many cases highly bespoke and maintained by small academic teams, in some instances by individuals approaching retirement. The Knowledge Management capability carries an average maturity score of 1.25, the joint-lowest score anywhere in this document, reflecting the recognised risk that key expertise may have single-person dependencies without documented succession arrangements. This does not meet the recommended target under (Principle 5: Minimum Capability Maturity), which recommends that critical-path entities demonstrate verifiable workforce resilience.
Risk: High — VLBI is the sole technique for UT1/CPO, and the analysis capacity behind it carries this document's lowest-scored capability (Knowledge Management). A key-person departure without documented succession would be a critical supply chain disruption with no observational alternative pathway.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| VLBI Data Processing and Analysis | 2.00 | 2.00 | 2.00 | 3.00 | 4 of 4 | 2.25 ⚠ |
| Knowledge Management | 1.00 | 2.00 | 1.00 | 1.00 | 4 of 4 | 1.25 ⚠ |
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F6 — Satellite Geodetic Analysis (PM/LOD)
Data level: Level 1 → Level 2 (intermediate) — uncombined satellite-technique EOP estimates (GNSS/SLR/DORIS SINEX).
The IGS Analysis Center Coordinator (ACC) combines individual analysis centre solutions to produce rapid and final combined estimates of Polar Motion and LOD. The International Laser Ranging Service (ILRS) and the International DORIS Service (IDS) provide supplementary PM and LOD estimates that serve as independent cross-checks and contribute to the final multi-technique combination at F7a/F7b. Unlike VLBI's single-pathway dependency for UT1, this function benefits from genuine multi-technique redundancy — GNSS, SLR, and DORIS each independently constrain PM and LOD.
Risk: Low — Multi-technique redundancy (GNSS, SLR, DORIS) across independent analysis centres gives this function's PM/LOD output the strongest resilience profile in the EOP workflow; GNSS Data Processing and Analysis is this document's highest-scored capability.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| GNSS Data Processing and Analysis | 4.00 | 4.00 | 3.00 | 4.00 | 4 of 4 | 3.75 |
(Source: State of Geodesy 2026)
F7a — Rapid Combination & Prediction (Bulletin A)
Data level: Level 3 EGV (Earth Orientation Parameters) — the official rapid combined EOP series.
The IERS Rapid Service and Prediction Center, operated by the US Naval Observatory (USNO), produces Bulletin A — a product published weekly but updated daily — which combines ultra-rapid GNSS estimates (F6) with VLBI Intensive session results (F5) to generate near-real-time EOP values and short-term predictions. Bulletin A is the product most directly consumed by space operations centres, deep space navigation teams, and precision timing networks, all of which require EOP estimates with latencies measured in hours.
This function is a single-institution, single-jurisdiction operation: it depends entirely on USNO, operating under U.S. federal jurisdiction. No formal international Service Level Agreement (SLA) or Memorandum of Understanding (MoU) binds USNO to defined performance standards for the Rapid Service function; the centre operates on a best-effort institutional basis under the IERS umbrella. The 2013, 2018–2019, and October–November 2025 U.S. government shutdown episodes demonstrated that even critical geodetic functions operated by federal agencies can experience service interruptions when appropriations lapse. No product delay attributable to any of these three episodes has been found in the available technical record for this assessment (Source: IGS 2018 Technical Report; NASA Shutdown Page; Planetary Society, 12 November 2025; see the Satellite Orbits Workflow annex, F5, for detailed sourcing of these events, and F4 above for the DOGE-related workforce reductions at NASA GSFC over the same period). The absence of a formal international backup arrangement for the Rapid Service function represents an unmitigated single point of failure in the global EOP supply chain and does not meet the recommended target under (Principle 3: Centralised Accountability through Multilateral Governance), which recommends that critical functions be backed by multilateral agreements and not subject to unilateral jurisdictional override.
Risk: Medium — Single-institution, single-jurisdiction operation with no formal international SLA; a correction from this document's prior framing, which described the combination function as "spanning two jurisdictions overall" together with F7b — that framing understated this track's individual exposure. (Principle 6: Transparency, Monitoring and Performance Assurance) recommends that this combination centre be subject to independent audits of SLA performance.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Risk Management | 1.00 | 1.00 | N/A | N/A | 2 of 4 | 1.00 ⚠ |
| Performance Management | 2.00 | 2.00 | N/A | N/A | 2 of 4 | 2.00 ⚠ |
| Geodetic Data Products | 2.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 2.75 |
| Reference Frames | 3.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
Note on this table: these four capabilities are scored at the combination step overall and shared with F7b below, not separately assessed per track — matching Work Assignment 2's own note on this point.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F7b — Definitive Combination (Bulletin B / IERS C04)
Data level: Level 3 EGV (Earth Orientation Parameters) — the official definitive and long-term combined EOP series.
The IERS EOP Product Center, operated by the SYRTE unit of the Observatoire de Paris, is responsible for the final, definitive EOP series. It produces Bulletin B — a monthly publication — and the IERS 14 C04 continuous long-term series. These products apply final solutions from all contributing technique services (F5, F6), enforce strict internal consistency with the ITRF and ICRF, and employ complex multi-technique weighting schemes that must reconcile the different temporal sampling characteristics of continuous GNSS and episodic VLBI. The weighting methodology must bridge the fundamental difference between the near-continuous PM and LOD coverage provided by GNSS and the episodic UT1 constraints provided by VLBI Intensives, requiring careful treatment of the formal errors and temporal covariances across techniques.
Like F7a, this function is a single-institution, single-jurisdiction operation: it depends entirely on SYRTE, operating under French jurisdiction. The same absence of a formal international SLA or MoU applies here — SYRTE operates on a best-effort institutional basis under the IERS umbrella, matching USNO's arrangement at F7a. (Principle 6: Transparency, Monitoring and Performance Assurance) applies equally to this centre.
Risk: Medium — High reliance on SYRTE institutional capability with no formal international SLA; a single-institution, single-jurisdiction operation in its own right, not offset by F7a's separate U.S. jurisdiction.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Risk Management | 1.00 | 1.00 | N/A | N/A | 2 of 4 | 1.00 ⚠ |
| Performance Management | 2.00 | 2.00 | N/A | N/A | 2 of 4 | 2.00 ⚠ |
| Geodetic Data Products | 2.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 2.75 |
| Reference Frames | 3.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
Note on this table: shared PPTD basis with F7a above — see note there.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F8 — Product Quality Assurance
Data level: Level 3 EGV (pre-dissemination) — validation checks applied to the combined EOP series before publication.
The IERS Central Bureau (BKG, Germany) and the IERS Directing Board perform quality-assurance functions on the combined EOP series before dissemination — including Atmospheric and Oceanic Angular Momentum (AAM/OAM) closure checks and frame-tie consistency verification against the ITRF and ICRF. This function is named separately here for the first time in this document's history: the prior five-tier structure did not surface it as its own step, folding it into "Validation and Distribution" alongside dissemination itself.
No capability in the current 58-capability State of Geodesy 2026 model is scored against this function. This is a genuine coverage gap, not a function with a low score — there is currently no maturity evidence of any kind for EOP-specific product quality assurance, distinct from the combination capabilities scored at F7a/F7b. Matching Work Assignment 2's own treatment of this same gap, it is flagged here rather than silently absorbed into F7a/F7b's or F9's tables.
Risk: Not assessed — no capability data exists to support a risk rating. The absence of any scored capability for this function is itself the finding.
(No capability table — see note above.)
F9 — Dissemination & User Access
Data level: Level 3 EGV (validated Earth Orientation Parameters) — published EOP series distributed globally.
The IERS distributes the finalised EOP products globally through three complementary product series. Bulletin A is published weekly by USNO (F7a), incorporating daily rapid updates and near-term predictions; it is the operational product series most directly consumed by space mission operators, navigation service providers, and precision timing networks. Bulletin B is published monthly by SYRTE (F7b) and provides the finalized, definitive EOP values for each preceding month, retrospectively superseding the rapid estimates in Bulletin A for applications requiring the highest accuracy. The IERS 14 C04 series provides the continuous, long-term, consistently processed EOP record extending across multiple decades and constitutes the primary reference for geodetic time series analysis and reference frame maintenance.
Distribution mechanisms for EOP products are mature by comparison with other elements of the supply chain; the IERS website infrastructure and the established FTP and web-based dissemination channels have operated reliably for decades. However, this maturity at the distribution layer does not translate into formal uptime guarantees. No SLA-backed availability commitment exists for either the USNO or SYRTE distribution endpoints, meaning that downstream users — including national geodetic authorities and space agencies — have no contractual recourse in the event of service interruption. The absence of geographic redundancy in the distribution architecture, and the lack of a formally documented disaster recovery protocol at either centre, are reflected in the low maturity scores for Geodetic Services and Disaster Recovery and Supply Chain Continuity.
Risk: Low — Distribution mechanisms are mature; the principal gap is the absence of formal SLA-backed uptime guarantees for end-users. (Principle 6: Transparency, Monitoring and Performance Assurance) recommends that distribution endpoints be subject to formal monitoring and public reporting obligations.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Geodetic Services | 2.00 | 2.00 | 2.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
| Data Distribution | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Disaster Recovery and Supply Chain Continuity | 2.00 | 2.00 | 1.00 | N/A | 3 of 4 | 1.67 ⚠ |
Note on this table: Geodetic Services is carried here per this document's own established scoring (see v5.0 changelog note above) though Work Assignment 2's current summary table for F9 omits it — flagged for reconciliation there.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
Capability Evidence Trail
Applying the confirmed/asserted/considered/queued method piloted on the Satellite Orbits annex. Every capability that appears in this document's function tables — 21 of the 58-capability model — is classified below by how it got its score. This is the starting draft the Technical Product Working Group is expected to confirm or challenge.
Confirmed — cited directly in this annex's function tables, at the shared State of Geodesy 2026 baseline, with no product-specific departure asserted (17 of 21 capabilities currently in this document):
- F1 (6): Ground-Based Asset Management, Equipment Calibration and Maintenance, SLR Data Acquisition and Storage, VLBI Data Acquisition and Storage, GNSS Data Acquisition and Storage, DORIS Data Acquisition and Storage
- F2 (1): Network Operations
- F3 (3): Data Quality Management, Metadata Management, Data Preservation
- F6 (1): GNSS Data Processing and Analysis
- F7a/F7b (4, shared, counted once): Geodetic Data Products, Reference Frames, Performance Management, Risk Management
- F9 (2, of 3 — see Considered below for the third): Geodetic Services, Data Distribution (flagged separately in its own table note as omitted from Work Assignment 2's current summary — see F9 above)
Asserted — none. No capability in this annex currently carries a product-specific numeric departure from the shared baseline.
Considered and not asserted — evidence exists but doesn't cleanly support a departure (4 of 21):
- VLBI Data Acquisition and Storage (F1, avg 3.00) — the IVS network's continued, undisrupted operation through the Russia-Ukraine conflict (Russian stations Zelenchukskaya, Badary, and Svetloe remained listed as active throughout 2022–2024) is real, product-specific evidence. It points toward resilience; left at baseline as a positive data point.
- GNSS Data Acquisition and Storage (F1, avg 3.50) — peer-reviewed research documents an approximately 10% reduction in operationally active Ukrainian GNSS stations following the February 2022 invasion. The same source states directly that no primary evidence confirms a resulting impact on EOP computation. Left at baseline; the evidence corroborates it.
- DORIS Data Acquisition and Storage (F1, avg 4.00) — the IDS's 2022 decommissioning of three Russian DORIS stations (Krasnoyarsk, Yuzhno-Sakhalinsk, Badary) is real, specific, sourced evidence of a documented coverage loss. It doesn't cleanly support lowering this capability's already-high baseline score: the loss affects roughly three of the network's approximately 60 global stations, and no evidence indicates the equipment, procedures, or data-handling practices this capability measures at the remaining stations were affected. Left at baseline; flagged for the Technical Product Working Group.
- Knowledge Management (F5, avg 1.25) — DOGE-related workforce reductions at NASA GSFC (approximately 32% of civil servants from February 2025 onward) and the October–November 2025 shutdown, both cited in this annex's F4 narrative, land directly on an institution this capability depends on. Already the joint-lowest score in the document; this evidence corroborates the baseline, matching the treatment the Satellite Orbits annex gives the same evidence against its own copy of this shared capability.
Queued — evidenced in this annex's prose or Governance table, not yet added to any function table, not yet dimension-level rated (4 capabilities):
- Mandate — F7a/F7b: both IERS Product Centres "operate on a best-effort institutional basis under the IERS umbrella," with no designated body actually accountable for combination performance. The Governance table names functional roles (SYRTE, USNO) but neither carries an explicit designation of formal authority.
- Funding and Investment — F4: VLBI correlation and analysis "relies significantly on in-kind institutional contributions, with inadequate dedicated funding creating latent fragility."
- Legal Framework — F7a/F7b: "absence of any formal international Service Level Agreement (SLA) or Memorandum of Understanding (MoU) binding either USNO or SYRTE to defined performance standards."
- Training and Education — F5: geodetic software "maintained by small academic teams, in some instances by individuals approaching retirement," with "single-person dependencies without documented succession arrangements." EOP has no Training and Education row in any function table, unlike ICRF and Gravity.
If asked why these four aren't scored yet: the honest answer is the same one Satellite Orbits gave — scoring them properly means the same per-dimension check the rest of this table went through.
Workflow Diagram
JDP Alignment
| Pipeline Element | Gap | JDP Objective |
|---|---|---|
| VLBI Network (F1) | Sparse, aging network with poor southern hemisphere coverage; single-technique dependency for UT1 | 1.2 — Regional hubs in under-represented regions; 1.3 — Formalised national backing |
| VLBI Correlation (F4) | Limited global correlator capacity; a throughput constraint or disruption at Washington or Bonn would delay rapid EOP products (structural risk; no specific incident recorded in IVS archive 2019–2024) | 1.2 — Modernised infrastructure |
| IERS Rapid Service at USNO (F7a) | No formal international SLA; U.S. federal jurisdiction introduces political risk; single-institution operation | 1.1 — SLAs and MoUs for critical functions |
| IERS EOP Product Center at SYRTE (F7b) | Best-effort institutional arrangement; no formal SLA-based monitoring; single-institution operation | 1.1 — Transparent accountability mechanisms |
| Product Quality Assurance (F8) | No capability in the current 58-capability model covers this function at all | 1.4 — Close capability model coverage gaps |
[^sog2026]: United Nations Global Geodetic Centre of Excellence, 2026, State of Geodesy 2026: A Baseline Maturity Assessment, Bonn, Germany, https://www.un.org/globalgeospatial/sites/default/files/2026-05/stateofgeodesy.pdf