Appearance
Research Findings: Re-derived Real Per-Product Function Lists, Ownership, and Risk Evidence
Engagement: UN-GGCE ToR2 — Global Geodesy Supply Chain Assessment
Document: Technical Research Findings: Function De-bundling, Operational Ownership, and Sourced Risk Evidence
Date: 22 September 2026
Status: Progressive Working Draft (Product-by-Product Validation)
Standard Alignment: BIZBOK® Guide (Business Architecture Guild), OMG BACM, and UN-GGCE Guiding Principles v4.6
Authoritative Capability Baseline: State of Geodesy 2026 (58 Capabilities, data/shacl/ggsc-capability-maturity.databook.md v1.4.0)
Executive Summary & Architectural Motivation
Work Assignment 2 (WA2 v4.1, outputs/2_product_mapping_report.md) mapped the five critical geodetic products into five high-level "Functions" (F0...F4). However, an architectural review against the UN-GGCE Head of Office's methodology (EOP_Worked_Example_GGSC.docx / outputs/project/eop_worked_example_v2.md) revealed that those five functions were a direct relabelling of the retired five-tier supply-chain structure (Observation, Archiving, Analysis, Combination, Distribution).
This coarse bundling obscures critical operational realities:
- Masked Capability Disparities: In EOP, VLBI analysis (PPTD 2.25 ⚠, the lowest-maturity capability in the entire EOP supply chain) and GNSS analysis (PPTD 3.75) were previously collapsed into a single "F2 — Technique Analysis Centres" row.
- Conflated Distinct Operational Facilities: Archiving repositories (such as CDDIS, IGN, SIO) and high-performance interferometric correlation facilities (Washington Correlator, Bonn Correlator) were bundled into "F1 — Archiving & Correlation," obscuring a critical physical throughput bottleneck.
- Hidden Single-Track Dependencies: Multi-jurisdictional combination steps (such as USNO in the USA and SYRTE in France) were treated as a single combined stage, concealing the reality that each distinct product track (Rapid Bulletin A vs Final Bulletin B/C04) is individually a single-jurisdiction, single-institution operation.
This document systematically re-derives the granular, evidence-based function list ($F_1 \dots F_n$) for all five critical products from primary scientific and coordinating service sources (IERS, IGS, IVS, ILRS, IDS, IGN, ICGEM, GFZ), validates operational ownership and jurisdiction per function, and re-anchors all published risk findings to their true functional homes.
1. Earth Orientation Parameters (EOP)
1.1 Proposed Granular Function List ($F_1 \dots F_9$)
The Earth Orientation Parameters supply chain is re-derived into nine distinct operational functions (with $F_7$ divided into two parallel, non-substitutable product tracks $F_{7a}$ and $F_{7b}$):
| Function | Official Name | Input Information Artifact | Output Information Artifact Produced | Scored State of Geodesy Capabilities | Sourced Rationale for Function Separation |
|---|---|---|---|---|---|
| F1 | Space Geodetic Multi-Technique Observation | Physical radio waves, laser pulses, GNSS radio frequencies | Raw Observational Baseband (Mark 6, VDIF, raw GNSS/DORIS binary) | Ground-Based Asset Management; Equipment Calibration and Maintenance; VLBI/GNSS/SLR/DORIS Data Acquisition | Physical tracking at telescopes/beacons. Distinct failure modes (mechanical, weather, cryogenic) from network transmission. |
| F2 | First-Mile Telemetry & Data Transmission | Raw Observational Baseband (local disks/buffers) | Transported Observational Baseband (streamed packets) | Network Operations | High-speed e-VLBI streaming and automated station push. Telemetry bandwidth at remote sites (e.g. Kokee Park, HartRAO) is the primary latency driver for rapid products. |
| F3 | Primary Data Archiving & Global Synchronization | Transported Observational Baseband / Daily Files | Standardized Observation Logs (vgosDB, RINEX 3/4, CRD) | Data Quality Management; Metadata Management; Data Preservation | Ingestion, format validation, and global mirroring across Global Data Centres (GDCs: CDDIS, IGN, SIO). Storage function, not computational processing. |
| F4 | VLBI Correlation & Fringe-Fitting | Raw recorded baseband data streams (Mark 6/VDIF) | Correlated Interferometric Observables (vgosDB delay & delay rate) | Geodetic Software and Tools; Network Operations | High-performance computing using specialized software/hardware correlators (DiFX) at Washington and Bonn. High-risk computational throughput bottleneck. |
| F5 | VLBI Technique Analysis (UT1-UTC & CPO) | Correlated delay observables (vgosDB) | Uncombined VLBI Solution (VLBI SINEX) | VLBI Data Processing and Analysis; Geodetic Software and Tools; Knowledge Management | IVS Analysis Centres estimating $UT1-UTC$ and Celestial Pole Offsets ($dX, dY$). Sole technique for UT1; lowest maturity in dataset (PPTD 2.25 ⚠). |
| F6 | Satellite Geodetic Analysis (Polar Motion & LOD) | Standardized GNSS RINEX, SLR CRD, DORIS logs | Uncombined Satellite Solutions (GNSS/SLR/DORIS SINEX) | GNSS Data Processing and Analysis; Geodetic Software and Tools | IGS, ILRS, and IDS Analysis Centres estimating daily/sub-daily Polar Motion ($x_p, y_p$) and Length of Day ($LOD$). High maturity (PPTD 3.75). |
| F7a | Rapid EOP Combination & Prediction (Bulletin A) | Rapid VLBI Intensives, IGS Ultra-Rapid/Rapid products, AAM/OAM | Integrated Rapid Solution (IERS Bulletin A, finals2000A.daily) | Geodetic Data Products; Reference Frames; Risk Management; Performance Management | Operated exclusively by USNO (USA). Daily update cycle, spline smoothing, and autoregressive time-series prediction for space operations. Single-jurisdiction. |
| F7b | Definitive Multi-Technique Combination (Bulletin B & C04) | Full multi-technique SINEX solutions (IVS, IGS, ILRS, IDS) | Integrated Definitive Solution (IERS Bulletin B, EOP 20 C04) | Geodetic Data Products; Reference Frames; Risk Management; Performance Management | Operated exclusively by SYRTE, Observatoire de Paris (France). Monthly cycle, Vondrák filter, and DYNAMO normal-equation combination aligned to ITRF/ICRF. |
| F8 | Product Quality Assurance & Dynamical Consistency | Preliminary Bulletin A and C04 series | Quality-Assurance Validated EOP Product Series | Standards Development and Promotion; Regulatory Compliance | Independent cross-technique validation, closure checks with atmospheric/oceanic angular momentum (AAM/OAM), and verification of frame tie alignment under IERS Directing Board. |
| F9 | Product Dissemination & User Access | Validated Bulletin A, Bulletin B, and EOP 20 C04 series | Published Ephemerides & Bulletins (FAIR APIs, FTP, Web) | Data Distribution; Geodetic Services; Disaster Recovery and Supply Chain Continuity | Public and machine-to-machine distribution via IERS web portals, USNO server endpoints, and mirror nodes for global space agencies and civil positioning. |
1.2 Ownership and Operational Jurisdiction per Function
- F1 (Observation): Multi-technique stations operated by national mapping and space agencies worldwide under the coordination of IVS, IGS, ILRS, and IDS. Jurisdiction: Globally distributed, multi-jurisdictional.
- F2 (Transmission): IVS Coordinating Centre (NASA GSFC / NVI Inc., USA); international academic research backbones (GÉANT Europe, Internet2 USA, AARNet Australia). Jurisdiction: Multi-jurisdictional.
- F3 (Archiving): The three apex Global Data Centres (GDCs): Crustal Dynamics Data Information System (CDDIS) at NASA GSFC (USA), Institut national de l'information géographique et forestière (IGN, France), and Scripps Institution of Oceanography (SIO, USA). Jurisdiction: Two sovereign jurisdictions (USA, France).
- F4 (Correlation): Primary geodetic correlators: Washington Correlator (NASA GSFC / USNO, USA) and Bonn Correlator (Max Planck Institute for Radio Astronomy / BKG, Germany); supported by MIT Haystack Observatory (USA). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F5 (VLBI Analysis): ~7 operational IVS Analysis Centres: BKG (Germany), NASA GSFC (USA), SYRTE / Paris Observatory (France), TU Vienna (Austria), Onsala Space Observatory (Sweden), Shanghai Astronomical Observatory (China), Geoscience Australia (Australia). Jurisdiction: Multi-jurisdictional (Europe, North America, Asia, Oceania).
- F6 (Satellite Analysis): 12+ IGS Analysis Centres (CODE, ESA/ESOC, GFZ, JPL, NGS, NRCan, GRGS, Wuhan University), ILRS Analysis Centres (ASI, GFZ, JCET), and IDS Analysis Centres (CNES, INASAN). Jurisdiction: Broadly multi-jurisdictional.
- F7a (Rapid Combination): IERS Rapid Service/Prediction Center (RS/PC) at the U.S. Naval Observatory (USNO), Washington DC. Jurisdiction: Single jurisdiction (USA).
- F7b (Definitive Combination): IERS Earth Orientation Center (EOC) at SYRTE, Observatoire de Paris. Jurisdiction: Single jurisdiction (France).
- F8 (Quality Assurance): IERS Central Bureau (BKG, Frankfurt, Germany) and IERS Directing Board (multilateral scientific governance under IAU/IUGG). Jurisdiction: International / Germany.
- F9 (Dissemination): IERS Central Bureau web portal (BKG, Germany), USNO public servers (USA), and Paris Observatory FTP servers (France). Jurisdiction: Multi-jurisdictional (Germany, USA, France).
1.3 Re-anchoring and Validation of Published Risk Findings
| Original Finding & Risk Type | Current WA2 Attachment | Re-anchored Granular Function | Validation Status & Sourced Evidence Update |
|---|---|---|---|
| Single-Technique Dependency for UT1 (Concentration / Technical SPoF) | Coarsely attached to Overview & Tier 0 | Attached to F1 (Observation) & F5 (VLBI Analysis) | Corroborated & Deepened. VLBI is the sole technique capable of measuring $UT1-UTC$ and CPO without drift accumulation. The global VLBI network is sparse in the southern hemisphere, and F5 carries the lowest capability maturity (PPTD 2.25 ⚠). Sourced: Bizouard et al. (2019); IERS Technical Note No. 40. |
| Correlator Throughput Bottleneck (Infrastructure SPoF) | Bundled into F1 (Archiving & Correlation) | Re-anchored to F4 (VLBI Correlation & Fringe-Fitting) | Corroborated. Geodetic correlation capacity is concentrated at Washington (NASA GSFC/USNO) and Bonn (MPIfR). If either correlator experiences hardware or network failure, intensive $UT1-UTC$ processing capacity is halved, immediately introducing latency into the Rapid Service. Sourced: IVS Biennial Reports 2019–2024. |
| USNO Federal Budget & Shutdown Vulnerability (Jurisdictional Risk) | Attached to F3 (EOP Combination) | Re-anchored to F7a (Rapid Combination & Prediction) | Corroborated & Updated. F7a is 100% reliant on USNO under U.S. Department of Defense / federal funding. During the 2013, 2018–2019, and 42-day October–November 2025 federal shutdowns, essential personnel sustained automated runs, but manual curation ceased. No formal international backup exists for Bulletin A rapid predictions. Sourced: IGS 2018 Technical Report; NASA Shutdown Notices; CNN (Nov 2025). |
| Key-Person Dependency at SYRTE (Succession Risk) | Attached to F3 (EOP Combination) | Re-anchored to F7b (Definitive Combination) | Corroborated. Definitive EOP combination (Bulletin B and EOP 20 C04) depends on a small scientific team at Paris Observatory (Dr. Christian Bizouard, Sébastien Lambert) utilizing specialized in-house DYNAMO and Vondrák filtering codes. No secondary operational institution mirrors this definitive combination. Sourced: Bizouard et al. (2019); IERS EOC Annual Reports. |
| CDDIS Single-Archive Dominance (Jurisdictional / Concentration Risk) | Bundled into F1 (Archiving & Correlation) | Re-anchored to F3 (Primary Data Archiving & Replication) | Corroborated. While IGN and SIO serve as GDC mirrors, CDDIS remains the primary ingestion point for historical and rapid VLBI vgosDB datasets. CDDIS experienced workforce reductions (~32% NASA GSFC civil servant reductions via DOGE from Feb 2025) and furlough during late 2025. Sourced: Space.com; Greenbelt News Review (2025). |
| Absence of Service Level Agreements (Governance Risk) | Attached to F3 (EOP Combination) | Attached across F7a, F7b, and F9 | Corroborated. Neither USNO nor SYRTE operates under a legally binding SLA or UN/intergovernmental MoU; operations are provided on a voluntary, best-effort institutional basis under IERS. Sourced: State of Geodesy 2026, Governance & Strategy baseline. |
1.4 New Material Findings Not Currently Captured in WA2
- Critical Physical Baseline Vulnerability for Rapid UT1: Operational rapid $UT1-UTC$ determination relies on IVS 1-hour Intensive sessions. Approximately 80% of routine weekday Intensives (INT1 series) are observed over the single baseline between Kokee Park Geophysical Observatory (Hawaii, USA) and Wettzell (Germany). A localized telecommunications or equipment outage at Kokee Park directly halts rapid UT1 turnaround until secondary baselines (e.g. Wettzell–Badary or Ishioka) can be scheduled, creating a physical single-baseline bottleneck upstream of F4 and F7a.
- Transition to EOP 20 C04 and ITRF2020: The IERS EOC formally operationalized the EOP 20 C04 series (aligned with ITRF2020), introducing daily consistency adjustments with celestial and terrestrial reference frames that require increased computational coordination with IGN (ITRF) and Paris Observatory (ICRF).
1.5 Sourced References for EOP
- Bizouard, C., et al. (2019). "The IERS EOP 14C04 solution for Earth orientation parameters consistent with ITRF 2014." Journal of Geodesy, 93(5), 621–633.
- IERS (2020). Explanatory Supplement to IERS Bulletins A and B. International Earth Rotation and Reference Systems Service, Observatoire de Paris / USNO.
- IVS (2024). International VLBI Service for Geodesy and Astrometry Biennial Report 2022–2023, NASA Goddard Space Flight Center.
- Stamatakos, N., et al. (2021). "The IERS Rapid Service/Prediction Center: Products and Accuracy." Proceedings of the Journées 2021.
- UN-GGCE (2026). State of Geodesy 2026: A Baseline Maturity Assessment, United Nations Global Geodetic Centre of Excellence, Bonn.
2. Satellite Orbits (GNSS)
2.1 Proposed Granular Function List ($F_1 \dots F_7$)
The GNSS Satellite Orbits supply chain is re-derived into seven distinct operational functions, untangling physical observation, telemetry, data hierarchy, analysis, combination, and validation:
| Function | Official Name | Input Information Artifact | Output Information Artifact Produced | Scored State of Geodesy Capabilities | Sourced Rationale for Function Separation |
|---|---|---|---|---|---|
| F1 | Global Multi-GNSS Network Tracking | Direct satellite radio frequencies (L-band, multi-GNSS) | Raw Observational Baseband (receiver-native binary observables) | Ground-Based Asset Management; Equipment Calibration and Maintenance; GNSS Data Acquisition and Storage | Continuous signal tracking across 659 global sites (106 ITRF Core Sites). Subject to local antenna, receiver, multipath, and environmental failures. |
| F2 | First-Mile Telemetry & Station Ingestion | Raw receiver binary (local storage buffer) | Transported GNSS Observation Streams (push/pull packets) | Network Operations | Real-time NTRIP streaming and automated hourly/daily push to Operational Data Centres (ODCs: GFZ, CNES REGINA, NGS). Northern-hemisphere concentration. |
| F3 | Regional & Global Data Archiving & Equalization | Transported GNSS observation packets | Standardized Observation Logs (RINEX 2/3/4) | Data Quality Management; Metadata Management; Data Preservation | Ingestion by Regional Data Centres (BKG, GA, KASI, SOPAC) and replication across the three Global Data Centres (CDDIS, IGN, SIO) via the GDC equalization protocol. |
| F4 | Technique Analysis Centre Processing | Synchronized RINEX observation files from GDCs | Uncombined AC Orbit & Clock Solutions (individual AC SP3, CLK, ERP) | GNSS Data Processing and Analysis; Geodetic Software and Tools; Knowledge Management | Distributed reduction by 12+ independent IGS Analysis Centres (CODE, ESA/ESOC, GFZ, JPL, NGS, NRCan, GRGS, etc.) using diverse software toolchains (Bernese, NAPEOS, EPOS, GipsyX, PANDA). |
| F5 | Multi-Centre Orbit & Clock Combination (ACC / SPOCC) | Uncombined individual AC SP3 and CLK solutions | Integrated Multi-Technique Solution (Combined IGS Final, Rapid, Ultra-Rapid SP3 & CLK) | Geodetic Data Products; Risk Management; Knowledge Management; Disaster Recovery and Supply Chain Continuity; Performance Management | Central combination engine executed by the IGS Analysis Centre Coordinator (ACC). Aligns solutions via Helmert transformations to ITRF using the SPOCC software. Single operational bottleneck. |
| F6 | Orbit Validation & Independent SLR Quality Assurance | Combined IGS SP3 orbits and ILRS SLR tracking data | Validated Orbit Products & Quality Reports (SLR residual time series) | Standards Development and Promotion; Regulatory Compliance | Independent optical verification: Satellite Laser Ranging (SLR) tracking of GNSS retroreflectors detects radial orbit errors independently of microwave signals. Coordinated with ILRS and IERS. |
| F7 | Global Product Dissemination & Real-Time Streaming | Validated IGS SP3 orbits, CLK clocks, and bias files | Published Ephemerides & Clock Biases (SP3, CLK, BIA, SSR streams) | Data Distribution; Geodetic Services | Open, global delivery of final/rapid/ultra-rapid files via CDDIS and IGS mirrors, alongside real-time broadcasting via the IGS Real-Time Service (RTS) NTRIP caster network. |
2.2 Ownership and Operational Jurisdiction per Function
- F1 (Tracking): Multi-GNSS tracking stations operated by national mapping agencies, research institutes, and universities across ~80 sovereign nations, coordinated under the IGS Infrastructure Committee. Jurisdiction: Broadly multi-jurisdictional.
- F2 (First-Mile Telemetry): Primary Operational Data Centres (ODCs): GFZ (Germany), CNES REGINA (France), and NGS/NOAA (USA). Telemetry backbones rely on national and academic internet infrastructure. Jurisdiction: Three jurisdictions (Germany, France, USA) — all in the Northern Hemisphere.
- F3 (Archiving & Equalization): Three apex Global Data Centres (GDCs): CDDIS (NASA GSFC, USA), IGN (France), and SIO (Scripps, USA); supported by Regional Data Centres (BKG Germany, Geoscience Australia, KASI South Korea, SOPAC USA). Jurisdiction: Two sovereign jurisdictions at the GDC level (USA, France).
- F4 (AC Processing): 12+ independent IGS Analysis Centres: Center for Orbit Determination in Europe (CODE, Switzerland/Europe), ESA/ESOC (Germany/Europe), GFZ (Germany), JPL (USA), NOAA/NGS (USA), Natural Resources Canada (NRCan, Canada), GRGS (France), Wuhan University (China), etc. Jurisdiction: Highly diversified multi-jurisdictional.
- F5 (ACC / SPOCC Combination): Analysis Centre Coordinator (ACC): Co-led by Geoscience Australia (Australia) and NASA GSFC (USA), joint leadership confirmed for the current term; combination software (SPOCC) developed, maintained, and operated at GFZ Potsdam (Germany). Jurisdiction: Australia, USA, and Germany.
- F6 (SLR Validation): International Laser Ranging Service (ILRS) network and ILRS Analysis Centres (NASA GSFC, ASI Italy, GFZ Germany), coordinated with the IGS Orbit Quality Working Group. Jurisdiction: Multi-jurisdictional.
- F7 (Dissemination): IGS Central Bureau (hosted at NASA JPL & GSFC, USA), CDDIS (USA), BKG (Germany), and IGN (France). Real-time NTRIP casters operated primarily by BKG and CDDIS. Jurisdiction: Multi-jurisdictional (USA, Germany, France).
2.3 Re-anchoring and Validation of Published Risk Findings
| Original Finding & Risk Type | Current WA2 Attachment | Re-anchored Granular Function | Validation Status & Sourced Evidence Update |
|---|---|---|---|
| ACC / SPOCC Convergence Bottleneck (Concentration / Technical SPoF) | Attached to F3 (ACC/SPOCC Combination) | Re-anchored to F5 (Multi-Centre Orbit & Clock Combination) | Corroborated. All upstream multi-centre diversity converges at the ACC. If SPOCC or the ACC fails, the official combined IGS orbit stream stops. Sourced: IGS Technical Reports; Spatial Source (2025). |
| SPOCC Software Monoculture (Technology SPoF / Knowledge Concentration) | Attached to F3 (ACC/SPOCC Combination) | Re-anchored to F5 (Multi-Centre Orbit & Clock Combination) | Corroborated. SPOCC is maintained almost exclusively by a small team at GFZ Potsdam. There is no parallel, fully validated community open-source combination software capable of automated operational replacement. Sourced: GFZ Potsdam; IGS ACC documentation. |
| ACC Transition Reintroducing U.S. Federal Jurisdiction (Jurisdictional Risk) | Attached to F3 (ACC/SPOCC Combination) | Re-anchored to F5 (Multi-Centre Orbit & Clock Combination) | Corroborated & Confirmed. The prior ACC structure (Geoscience Australia / MIT) sat outside U.S. federal agency control, enabling complete operational continuity during the 2018–2019 U.S. federal shutdown. The new joint leadership with NASA GSFC re-exposes the ACC role to U.S. federal appropriations lapses and furlough mandates. Sourced: Spatial Source (2025); NASA GSFC Announcement (2025). |
| Untested GDC Equalization Protocol (Resilience / Interoperability Risk) | Attached to F1 (Data Centres) | Re-anchored to F3 (Regional & Global Archiving & Equalization) | Corroborated. While designed to synchronize holdings continuously across CDDIS, IGN, and SIO, no planned failover drill has ever been executed, and no documented instance of an AC switching to IGN/SIO occurred during federal shutdowns. Sourced: CDDIS 2007 incident record; IGS Technical Reports. |
| ODC Northern Hemisphere Concentration (Geographic Distribution Risk) | Coarsely referenced under F0 / Overview | Re-anchored to F2 (First-Mile Telemetry & Ingestion) | Corroborated. All three primary ODCs (GFZ, CNES, NGS) are in the northern hemisphere, conflicting with Principle 1 and creating latency vulnerabilities for southern-hemisphere tracking stations. Sourced: IGS Infrastructure Committee Data Flow Topology. |
| NASA GSFC & JPL Institutional Stress (Workforce & Continuity Risk) | Cited across F1, F2, and F3 | Re-anchored to F3 (CDDIS), F5 (ACC Lead), and F7 (Central Bureau) | Corroborated & Updated. NASA GSFC civil servant reductions (~32% from Feb 2025 onward) and the Oct–Nov 2025 federal shutdown directly impacted CDDIS and GSFC's ACC participation. JPL experienced ~25% staff reductions in 2024–2025 and a 6-day disruption during the Jan 2025 wildfires. Sourced: Space.com; Greenbelt News Review (2025); CNN (Nov 2025). |
2.4 New Material Findings Not Currently Captured in WA2
- Formal Joint ACC Leadership Sourcing: The transition of the IGS ACC to joint leadership between Geoscience Australia and NASA GSFC (with continued technical support from GFZ and MIT) is formally documented and operational for the 2025–2028 term, clarifying the operational division of labor between GA (primary operational coordination) and GSFC (scientific and computational support).
- IGS Real-Time Service (RTS) Dissemination Dependency: In addition to file-based SP3/CLK dissemination, modern GNSS orbit delivery relies heavily on the IGS Real-Time Service (RTS), which broadcasts State Space Representation (SSR) corrections via NTRIP. The operational infrastructure for these casters is heavily concentrated at BKG (Germany) and CDDIS (USA), creating a streaming single-point-of-failure distinct from static FTP archives.
2.5 Sourced References for Satellite Orbits
- International GNSS Service (2024). IGS Technical Report 2023, edited by A. Villiger and R. Dach, IGS Central Bureau.
- Mansur, G., et al. (2024). "SPOCC: The IGS Combination Software for Orbits and Clocks." Advances in Space Research.
- Spatial Source (2025). "Geoscience Australia, NASA GSFC to act as IGS ACC." https://www.spatialsource.com.au/geoscience-australia-nasa-gsfc-to-act-as-igs-acc/.
- NASA Goddard Space Flight Center (2025). "New IGS Analysis Center Coordinator Announced." https://earth.gsfc.nasa.gov/geo/projects/sgp/updates/new-igs-analysis-center-coordinator-announced.
- UN-GGCE (2026). State of Geodesy 2026: A Baseline Maturity Assessment, United Nations Global Geodetic Centre of Excellence, Bonn.
3. International Terrestrial Reference Frame (ITRF)
3.1 Proposed Granular Function List ($F_1 \dots F_9$)
The International Terrestrial Reference Frame supply chain is re-derived into nine distinct operational functions, isolating physical multi-technique tracking, local tie geodesy, data archiving, VLBI correlation, intra-technique reduction, central combination, independent multi-centre validation, and formal designation:
| Function | Official Name | Input Information Artifact | Output Information Artifact Produced | Scored State of Geodesy Capabilities | Sourced Rationale for Function Separation |
|---|---|---|---|---|---|
| F1 | Multi-Technique Space Geodetic Ground Tracking | Physical radio signals, laser pulses, GNSS frequencies | Raw Observational Baseband (multi-technique raw files) | Ground-Based Asset Management; Equipment Calibration and Maintenance; GNSS/VLBI/SLR/DORIS Data Acquisition and Storage | Physical tracking across ~500+ GNSS, ~40 VLBI, ~40 SLR, and ~60 DORIS stations. Severe southern-hemisphere and African spatial disparities. |
| F2 | Co-Location Local Tie Surveys & Monitoring | Physical monument geometries, levelling benchmarks | Local Tie Survey Vectors & SINEX Files | Local Tie; Local Tie Processing and Analysis | Terrestrial measurement linking invariant reference points of co-located instruments at ~107 Core Sites. Crucial physical constraint holding multi-technique frame together; previously buried inside F0. |
| F3 | First-Mile Telemetry & Data Transport | Raw local observational data buffers | Transported Multi-Technique Data Streams | Network Operations | Distinct telemetry streams: e-VLBI broadband, real-time/hourly GNSS pushes, daily SLR normal point uploads, and DORIS beacon monitoring. |
| F4 | Global Multi-Technique Archiving & Synchronization | Transported data files and streams | Standardized Observation Logs (RINEX 3/4, vgosDB, CRD, DORIS 2.2) | Data Quality Management; Metadata Management; Data Preservation | Ingestion, format compliance, and mirroring across Global Data Centres (CDDIS, IGN, SIO). Two-jurisdiction concentration. |
| F5 | VLBI Correlation & Delay Extraction | Raw baseband voltage streams (Mark 6/VDIF) | Correlated Interferometric Observables (vgosDB delay & delay rate) | Geodetic Software and Tools; Network Operations | Specialized hardware/software computing (DiFX at Washington and Bonn) converting terabytes of raw baseband into interferometric delay observables. Distinct throughput bottleneck previously hidden in F1. |
| F6 | Intra-Technique Analysis & Service Combination | Standardized observation logs and correlated delays | Intra-Technique Combined Solutions (technique-specific SINEX) | GNSS/VLBI/SLR/DORIS Data Processing and Analysis; Geodetic Software and Tools | Technique coordinating services (IGS, IVS, ILRS, IDS) coordinating independent Analysis Centres: SLR defines geocentre/origin; VLBI defines scale and celestial tie; GNSS/DORIS provide spatial density. |
| F7 | Multi-Technique ITRS Combination & Stacking (IGN / CATREF) | Intra-technique SINEX solutions and local tie vectors | Integrated Multi-Technique Solution (Official ITRF Solution, SINEX, PSD models) | Geodetic Data Products; Reference Frames; Knowledge Management; Local Tie Processing and Analysis | Performed by the ITRS Product Centre at IGN (France) using CATREF software. Stacks multi-decadal time series, estimates positions, velocities, and post-seismic deformation (PSD). Single-institution bottleneck. |
| F8 | Independent Solution Cross-Validation & Consistency Verification | Intra-technique SINEX solutions and local ties | Validated Multi-Centre Reference Frame Solutions & Inter-Comparison Reports | Research and Development Prototyping; Standards Development and Promotion; Regulatory Compliance | Parallel independent combination by DGFI-TUM (Germany, DTRF via DOGS) and NASA JPL (USA, JTRF via Kalman filter). Essential scientific validation step ensuring mathematical integrity before adoption. |
| F9 | Formal Product Designation & Global Dissemination | Validated ITRF Solution and inter-comparison dossiers | Published ITRF Realisation (Official ITRF2020 coordinate sets, velocity fields, PSD grids) | Data Distribution; Geodetic Services; Disaster Recovery and Supply Chain Continuity | Formal review and official adoption by the IERS Directing Board, IAG, and IAU; dissemination via ITRS Product Centre (IGN) and IERS web/FTP portals. |
3.2 Ownership and Operational Jurisdiction per Function
- F1 (Ground Tracking): Globally distributed multi-technique stations operated by national mapping agencies, space agencies, and universities under IGS, IVS, ILRS, and IDS. Jurisdiction: Broadly multi-jurisdictional.
- F2 (Local Ties): National surveying and mapping authorities at observatory sites; international mobile survey teams from IGN (France) and national geodetic agencies. Jurisdiction: Multi-jurisdictional.
- F3 (Telemetry): National research and education networks, commercial telecoms, and station operators. Jurisdiction: Multi-jurisdictional.
- F4 (Archiving & Synchronization): Global Data Centres: CDDIS (NASA GSFC, USA), IGN (France), SIO (USA). Jurisdiction: Two sovereign jurisdictions (USA, France).
- F5 (VLBI Correlation): Washington Correlator (NASA GSFC / USNO, USA), Bonn Correlator (MPIfR / BKG, Germany), Haystack Correlator (USA). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F6 (Intra-Technique Analysis):
- IGS ACC (Geoscience Australia & NASA GSFC; Australia, USA)
- IVS Analysis Coordinator (NASA GSFC; USA)
- ILRS Combination Centre (ASI Matera; Italy / JCET; USA)
- IDS Central Bureau and Combination Centre (CLS / CNES; France) Jurisdiction: Multi-jurisdictional (Australia, USA, Germany, Italy, France).
- F7 (ITRS Combination): ITRS Product Centre at Institut national de l'information géographique et forestière (IGN, Paris, France), governed by the IERS Directing Board. Jurisdiction: Single jurisdiction (France).
- F8 (Independent Cross-Validation): Deutsches Geodätisches Forschungsinstitut, Technical University of Munich (DGFI-TUM, Munich, Germany) and Jet Propulsion Laboratory (NASA JPL, Pasadena, USA). Jurisdiction: Two sovereign jurisdictions (Germany, USA).
- F9 (Designation & Dissemination): IERS Directing Board (international multilateral governance); distribution servers at IGN (France) and IERS Central Bureau (BKG, Germany). Jurisdiction: International / France / Germany.
3.3 Re-anchoring and Validation of Published Risk Findings
| Original Finding & Risk Type | Current WA2 Attachment | Re-anchored Granular Function | Validation Status & Sourced Evidence Update |
|---|---|---|---|
| CATREF Software & IGN Key-Person Concentration (Concentration / Succession SPoF) | Attached to F3 (ITRS Combination) | Re-anchored to F7 (Multi-Technique ITRS Combination & Stacking) | Corroborated. The official ITRF realization relies entirely on the CATREF software package developed and operated by a small team at IGN (Dr. Zouhair Altamimi, Paul Rebischung). No alternative community software is currently validated for official ITRF production. Sourced: Altamimi et al. (2023); ITRS Product Centre. |
| GDC Archive Concentration & Shutdown Risk (Jurisdictional / Continuity Risk) | Attached to F1 (Global Archiving) | Re-anchored to F4 (Global Multi-Technique Archiving & Synchronization) | Corroborated & Updated. GDC holdings span only two jurisdictions (USA, France). CDDIS suffered staffing furloughs and disruption during 2013, 2018–2019, and late 2025 federal shutdowns, and lost ~32% of civil servants in 2025. BKG (an RDC) openly reports having no disaster recovery capability. Sourced: IGS Technical Reports; Space.com; Greenbelt News Review (2025). |
| Local Tie Measurement Deficiencies (Technical Risk / Data SPoF) | Coarsely referenced under F0 / Overview | Re-anchored to F2 (Co-Location Local Tie Surveys & Monitoring) | Corroborated & Deepened. Discrepancies between local tie vectors and space geodetic solutions (frequently exceeding 5–10 mm) represent one of the largest systematic error sources in ITRF realization. Scored Technology 1.00 at F2. Sourced: Altamimi et al. (2023); IERS Technical Note No. 41. |
| SLR Geocentre & VLBI Scale Single-Technique Dependencies (Technical SPoF) | Coarsely referenced under F0 / Overview | Attached across F1 (Tracking) and F6 (Intra-Technique Analysis) | Corroborated. SLR is the sole technique providing origin (geocentre) definition and contributes to scale; VLBI is the sole independent technique defining scale without satellite orbit modeling assumptions. Loss or geographic degradation of either technique directly corrupts fundamental frame parameters. Sourced: Altamimi et al. (2023). |
| Independent Validators Lack Operational Replacement Mandate (Governance Risk) | Attached to F3 (ITRS Combination) | Re-anchored to F8 (Independent Solution Cross-Validation) | Corroborated. While DGFI-TUM (DTRF) and NASA JPL (JTRF) compute independent reference frame solutions, neither possesses an official operational mandate from IERS to substitute for IGN in the event of an institutional shutdown or failure. Sourced: IERS Directing Board Terms of Reference. |
3.4 New Material Findings Not Currently Captured in WA2
- ITRF2020 Linear and Non-Linear Modeling Dependencies: The operational release of ITRF2020 (Altamimi et al., 2023) introduced Post-Seismic Deformation (PSD) models for over 120 stations and non-tidal atmospheric loading (NTAL) corrections. This substantially increased the algorithmic complexity of F7, deepening the technical dependence on specialized CATREF code routines and widening the knowledge barrier for potential successor institutions.
- GENESIS Mission as Future Space Tie Validator: The European Space Agency's approved GENESIS satellite mission (co-locating GNSS, VLBI, SLR, and DORIS in orbit with calibrated phase centers) represents a major upcoming architectural evolution that will validate and calibrate ground local ties (F2), directly mitigating the local tie systematic error bottleneck by 2028+.
3.5 Sourced References for ITRF
- Altamimi, Z., Rebischung, P., Collilieux, X., Métivier, L., & Chanard, K. (2023). "ITRF2020: an augmented reference frame refining the modeling of nonlinear station motions." Journal of Geodesy, 97(5), 47.
- IERS (2023). IERS Annual Report 2022, International Earth Rotation and Reference Systems Service Central Bureau, BKG, Frankfurt.
- Rebischung, P., & Altamimi, Z. (2023). "CATREF Software Documentation and Combination Strategy for ITRF2020." IERS Technical Note No. 41.
- UN-GGCE (2026). State of Geodesy 2026: A Baseline Maturity Assessment, United Nations Global Geodetic Centre of Excellence, Bonn.
4. International Celestial Reference Frame (ICRF)
4.1 Proposed Granular Function List ($F_1 \dots F_8$)
The International Celestial Reference Frame supply chain is re-derived into eight distinct operational functions, untangling physical radio observation, media logistics, primary archiving, correlation, individual AC astrometric reduction, multi-catalogue combination, astrophysical source structure validation, and formal designation:
| Function | Official Name | Input Information Artifact | Output Information Artifact Produced | Scored State of Geodesy Capabilities | Sourced Rationale for Function Separation |
|---|---|---|---|---|---|
| F1 | Astrometric & Geodetic VLBI Observations | High-frequency cosmic radio emissions (quasars) | Raw Observational Baseband (recorded voltages on Mark 6 / flexbuf) | Ground-Based Asset Management; Equipment Calibration and Maintenance; VLBI Data Acquisition and Storage | Multi-frequency tracking (S/X, K, X/Ka bands) across ~40 radio telescopes globally, synchronized via hydrogen masers. Severe southern hemisphere geometric deficit. |
| F2 | Raw Data Logistics & Telemetry Transport | Raw recorded baseband disks / buffers | Transported Interferometric Data Streams & Disk Shipments | Network Operations | Dual-path data delivery: physical courier shipping of multi-terabyte Mark 6 disk packs (days/weeks latency for remote sites) and electronic e-VLBI broadband transfers. |
| F3 | Primary Data Archiving & Metadata Registration | Transported baseband data and station logs | Standardized Observation Logs (vgosDB session archives) | Data Quality Management; Metadata Management; Data Preservation | Centralized ingestion of session logs, calibration files, and metadata at CDDIS (NASA GSFC, USA) and BKG (Germany). Storage and preservation layer. |
| F4 | Interferometric Correlation & Fringe-Fitting | Raw recorded baseband data streams (Mark 6/VDIF) | Correlated Interferometric Observables (vgosDB delay and delay rate) | Geodetic Software and Tools; Network Operations | Purpose-built software correlators (DiFX) at Washington (NASA GSFC / USNO), Bonn (MPIfR / BKG), and Haystack. A severe throughput bottleneck: failure at a major correlator halts all scheduled sessions. |
| F5 | Astrometric VLBI Analysis & Individual Catalogue Production | Correlated interferometric observables (vgosDB) | Uncombined Celestial Catalogues & Normal Equations (individual AC source coordinate tables) | VLBI Data Processing and Analysis; Geodetic Software and Tools; Knowledge Management; Training and Education | Parameter estimation by IVS Analysis Centres (NASA GSFC, Paris Obs, TU Vienna, BKG, SHAO, etc.) using Calc/Solve, VieVS, etc., solving for Right Ascension and Declination of radio sources. Small global analyst pool. |
| F6 | ICRS Multi-Catalogue Combination & Global Frame Realization | Individual AC celestial catalogues and normal equations | Integrated Celestial Reference Frame Solution (Combined ICRF Solution, covariance matrices) | Geodetic Data Products; Reference Frames; Research and Development Prototyping | Core combination led by the IERS ICRS Centre (Observatoire de Paris / SYRTE and BKG) and the IAU Working Group on ICRF. Enforces No-Net-Rotation alignment and selects defining sources (e.g. 303 in ICRF3). |
| F7 | Astrophysical Source Structure & Multi-Wavelength Validation | Combined radio source coordinates and optical Gaia catalogues | Validated Source Stability Indices & Gaia-VLBI Offset Reports | Research and Development Prototyping; Standards Development and Promotion | Physical quality control: evaluates intrinsic radio source structure (parsec-scale jets) using closure phase analysis, and cross-validates against optical astrometry from ESA Gaia (Gaia-CRF3). |
| F8 | Formal IAU Designation & Global Catalogue Dissemination | Validated ICRF Catalogue and resolution dossiers | Published ICRF Catalogue (Official ICRF3 Catalogue, CDS tables) | Data Distribution; Geodetic Services; Regulatory Compliance; Standards Development and Promotion | Formal adoption by the International Astronomical Union (IAU) General Assembly via formal resolution. Global publication via CDS Strasbourg, IERS, and IAU archives. |
4.2 Ownership and Operational Jurisdiction per Function
- F1 (VLBI Observations): ~40 radio telescopes operated by national space agencies, astronomical observatories, and universities under the International VLBI Service for Geodesy and Astrometry (IVS). Jurisdiction: Broadly multi-jurisdictional, but heavily concentrated in the Northern Hemisphere.
- F2 (Data Logistics): International postal/courier services (physical disks); academic research networks (GÉANT, Internet2, AARNet). Jurisdiction: Multi-jurisdictional.
- F3 (Archiving): Crustal Dynamics Data Information System (CDDIS at NASA GSFC, USA) and Bundesamt für Kartographie und Geodäsie (BKG, Germany). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F4 (Correlation): Primary correlators: Washington Correlator (NASA GSFC / USNO, USA), Bonn Correlator (Max Planck Institute for Radio Astronomy / BKG, Germany), and MIT Haystack Observatory (USA). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F5 (Astrometric Analysis): Fewer than 10 active IVS Analysis Centres for ICRF: NASA GSFC (USA), Observatoire de Paris (France), TU Vienna (Austria), BKG (Germany), Shanghai Astronomical Observatory (China), Institute of Applied Astronomy (Russia), Geoscience Australia (Australia). Jurisdiction: Multi-jurisdictional.
- F6 (ICRS Combination): IERS ICRS Centre, co-hosted by Observatoire de Paris / SYRTE (France) and BKG (Germany), working under the IAU Working Group on the ICRF. Jurisdiction: Two sovereign jurisdictions (France, Germany).
- F7 (Astrophysical Validation): Bordeaux Observatory (Laboratoire d'Astrophysique de Bordeaux, France), US Naval Observatory (USA), and the IAU Commission A2 (Rotation of the Earth) / Commission A1 (Astrometry). Jurisdiction: France and USA.
- F8 (Designation & Dissemination): International Astronomical Union (IAU) General Assembly; Centre de Données astronomiques de Strasbourg (CDS, France) and IERS ICRS Centre (France/Germany). Jurisdiction: International / France.
4.3 Re-anchoring and Validation of Published Risk Findings
| Original Finding & Risk Type | Current WA2 Attachment | Re-anchored Granular Function | Validation Status & Sourced Evidence Update |
|---|---|---|---|
| Correlator Inventory Bottleneck (Infrastructure SPoF) | Bundled into F1 (Archiving & Correlation) | Re-anchored to F4 (Interferometric Correlation & Fringe-Fitting) | Corroborated & Deepened. Fewer than ten geodetic-grade correlators exist worldwide, with routine operational load concentrated at Washington, Bonn, and Haystack. Correlation throughput directly governs session completion. Sourced: Charlot et al. (2020); IVS Biennial Reports. |
| Dual-Hosting Concentration at NASA GSFC (Jurisdictional / Institutional SPoF) | Noted across F1 and F2 narrative | Re-anchored to F3 (CDDIS) and F4 (Washington Correlator) | Corroborated & Updated. NASA GSFC hosts both CDDIS (the primary global archive) and the Washington Correlator (the primary US correlator), plus the maintenance of the primary Calc/Solve software. NASA GSFC experienced ~32% civil servant staff reductions from Feb 2025 and a 42-day shutdown in late 2025. Sourced: Space.com; Greenbelt News Review (2025). |
| Sparse Southern Hemisphere Observatories (Geographic Distribution Risk) | Attached to F0 (VLBI Network Acquisition) | Re-anchored to F1 (Astrometric & Geodetic VLBI Observations) | Corroborated. Deficits in southern hemisphere radio telescopes limit the observation of southern celestial hemisphere radio sources, leading to higher declination errors in the south. Sourced: Charlot et al. (2020), Astronomy & Astrophysics. |
| Small Global Analyst Community & Software Monoculture (Succession / Technology Risk) | Attached to F2 (IVS Analysis Centres) | Re-anchored to F5 (Astrometric VLBI Analysis) | Corroborated. The number of analysts capable of producing full celestial reference frame catalogues is critically small (<20 globally), with heavy reliance on legacy Calc/Solve code maintained at NASA GSFC. Sourced: State of Geodesy 2026, Training & Education (scored 1.25). |
| Question of EU/NATO Jurisdictional Independence (Jurisdictional Open Question) | Attached to Principle 2 findings | Re-anchored to F4 (Correlation) and F6 (Combination) | Status Clarified. The primary correlators (USA, Germany) and combination centres (France, Germany) reside in allied EU/NATO nations. Whether shared security frameworks constitute single geopolitical jurisdiction risk remains an open policy question for UN Member States. Sourced: UN-GGCE ToR2 Risk Register. |
4.4 New Material Findings Not Currently Captured in WA2
- Multi-Wavelength Realization of ICRF3: ICRF3 (adopted by IAU Resolution B2 in 2018) was the first celestial reference frame realized at multiple radio frequencies: S/X band (8.4 GHz, 4,536 sources), K band (24 GHz, 824 sources), and X/Ka band (32 GHz, 678 sources). This introduced distinct technique-dependent systematic errors that require specialized multi-frequency handling at F6, a complexity not reflected in the current single-track description.
- Optical Cross-Validation with ESA Gaia: The alignment between the radio ICRF and the optical Gaia-CRF3 (derived from billion-star space astrometry) is now an established operational validation step at F7. Astrometric offsets ("core-shifts") between radio and optical centroids provide direct physical diagnostic checks on quasar stability.
4.5 Sourced References for ICRF
- Charlot, P., et al. (2020). "The third realization of the International Celestial Reference Frame by very long baseline interferometry (ICRF3)." Astronomy & Astrophysics, 644, A159.
- International Astronomical Union (2018). Resolutions of the XXXth IAU General Assembly, Vienna, Austria, Resolution B2 on ICRF3.
- IVS (2024). International VLBI Service for Geodesy and Astrometry Biennial Report 2022–2023, NASA GSFC.
- UN-GGCE (2026). State of Geodesy 2026: A Baseline Maturity Assessment, United Nations Global Geodetic Centre of Excellence, Bonn.
5. Global Earth Gravity Field
5.1 Proposed Granular Function List ($F_1 \dots F_9$)
The Global Earth Gravity Field supply chain is re-derived into nine distinct operational functions, untangling satellite gravimetry, terrestrial/marine data collection, dual-stream archiving, satellite Level-2 analysis, time-variable combination (COST-G), surface anomaly harmonization, ultra-high-degree static combination, benchmark geoid validation, and open service dissemination:
| Function | Official Name | Input Information Artifact | Output Information Artifact Produced | Scored State of Geodesy Capabilities | Sourced Rationale for Function Separation |
|---|---|---|---|---|---|
| F1 | Satellite Gravimetry Space Mission Operations | Inter-satellite range-rates, GPS tracking, accelerometer non-gravitational forces | Raw Satellite Telemetry & Level-1a Data | Ground-Based Asset Management; Equipment Calibration and Maintenance; Gravity Data Acquisition and Storage | Spaceborne sensing: GRACE-FO (NASA/GFZ) providing continuous long/medium-wavelength global sampling. Critical SPoF: lack of funded successor mission creates temporal continuity risk (WA3 Gap 6). |
| F2 | Terrestrial, Airborne & Marine Gravimetry Acquisition | Terrestrial gravity readings, airborne/marine accelerometer records | Raw Terrestrial/Airborne/Marine Gravity Observations | Ground-Based Asset Management; Equipment Calibration and Maintenance; Gravity Data Acquisition and Storage | Physical acquisition of short-wavelength, high-frequency gravity signals. Severe global distributional inequity (sparse across Africa, South America, oceans). |
| F3 | Dual-Stream Data Archiving & Global Collation | Raw satellite data and contributed terrestrial anomaly files | Standardized Observation Logs & Anomaly Datasets (Level-1b satellite data, BGI anomaly archives) | Data Quality Management; Metadata Management; Data Preservation; Data Sharing | Distinct archives: NASA PO.DAAC / GFZ for satellite data, and Bureau Gravimétrique International (BGI, France) for surface data. Sensitive commercial/defense data silos hinder FAIR access. |
| F4 | Satellite Gravity Field Processing & Level-2 Solution Generation | Calibrated GRACE-FO Level-1b data | Uncombined Satellite Gravity Solutions (Monthly Level-2 spherical harmonic coefficients $C_{nm}, S_{nm}$) | Gravity Data Processing and Analysis; Geodetic Software and Tools | Independent reduction of satellite orbit perturbations by Science Data System (SDS) centres: CSR (Univ. of Texas), NASA JPL, and GFZ Potsdam. Algorithmic diversity. |
| F5 | Time-Variable Gravity Multi-Centre Combination (COST-G) | Independent monthly Level-2 solutions from CSR, JPL, GFZ, CNES | Integrated Time-Variable Gravity Solutions (COST-G combined monthly gravity fields) | Geodetic Data Products; Research and Development Prototyping; Standards Development and Promotion | Operational combination under IAG/IGFS hosted at AIUB (Bern, Switzerland). Combines monthly fields for mass transport applications (ice mass loss, hydrological aquifer monitoring). |
| F6 | Surface Gravity Anomaly Harmonization & Grid Synthesis | Terrestrial, airborne, marine anomalies and digital elevation models | Global Surface Gravity Anomaly Grids (5' to 1' grids) | Gravity Data Processing and Analysis; Geodetic Software and Tools; Data Quality Management | Formatting, datum transformation, Bouguer/free-air reduction, terrain correction, and spatial gridding performed by BGI, NGA, and national agencies. Pre-requisite for high-degree combination. |
| F7 | Ultra-High-Degree Global Gravity Field Combination | Satellite-only models (GRACE-FO/GOCE) and surface gravity grids | Integrated Multi-Technique Solution (Global Earth Gravity Field Models, degree/order 2190) | Geodetic Data Products; Research and Development Planning; Research and Development Prototyping; Knowledge Management | Massive computational combination merging satellite and surface data into ultra-high-degree spherical harmonic models (e.g. EGM2008, XGM2019e). Infrequent, highly concentrated undertaking (NGA, GFZ, TU Munich). |
| F8 | Geoid Model Evaluation & Independent Benchmark Validation | Combined global gravity models and external geodetic benchmarks | Validated Geoid Models & Quality Assessment Dossiers (standard deviations against GPS-levelling) | Standards Development and Promotion; Regulatory Compliance | Independent quality verification: comparing model-derived geoid heights against global GPS/levelling benchmarks, astrogeodetic vertical deflections, and ocean Mean Dynamic Topography (MDT). |
| F9 | Model Archiving, Calculation Services & Global Dissemination | Validated spherical harmonic coefficient models | Published Global Gravity Field Models & Calculation Services (FAIR web portal, online grids) | Data Distribution; Geodetic Services; Data Sharing | International Centre for Global Earth Models (ICGEM, GFZ Potsdam, Germany). Definitive global clearinghouse, interactive online calculation service, and model evaluation repository. |
5.2 Ownership and Operational Jurisdiction per Function
- F1 (Satellite Operations): Joint mission operations between NASA (USA) and German Research Centre for Geosciences (GFZ) (Germany). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F2 (Surface Acquisition): National mapping and geological agencies, naval/military authorities, airborne survey operators, and commercial exploration companies worldwide. Jurisdiction: Broadly multi-jurisdictional, with major geographic coverage gaps in developing nations.
- F3 (Archiving):
- Satellite Level-1b: NASA Physical Oceanography Distributed Active Archive Centre (PO.DAAC at JPL, USA) and GFZ ISDC (Germany).
- Surface Gravity: Bureau Gravimétrique International (BGI / International Gravity Field Service, Toulouse, France). Jurisdiction: USA, Germany, France.
- F4 (Satellite Analysis): GRACE-FO Science Data System (SDS): Center for Space Research at University of Texas at Austin (CSR, USA), NASA Jet Propulsion Laboratory (JPL, USA), and GFZ Potsdam (Germany). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F5 (COST-G Combination): Combination Service for Time-variable Gravity Fields (COST-G), hosted at the Astronomical Institute of the University of Bern (AIUB), Switzerland, operating under the International Gravity Field Service (IGFS / IAG). Jurisdiction: Switzerland / International.
- F6 (Surface Harmonization): Bureau Gravimétrique International (France), National Geospatial-Intelligence Agency (NGA, USA), and regional geoid working groups. Jurisdiction: France and USA.
- F7 (Ultra-High-Degree Combination): National Geospatial-Intelligence Agency (NGA, USA), German Research Centre for Geosciences (GFZ, Germany), and Technical University of Munich (TU Munich, Germany). Jurisdiction: Two sovereign jurisdictions (USA, Germany).
- F8 (Benchmark Validation): International Gravity Field Service (IGFS / IAG Commission 2), national geodetic agencies, and international academic evaluation teams. Jurisdiction: Broadly multi-jurisdictional.
- F9 (ICGEM Dissemination): International Centre for Global Earth Models (ICGEM), hosted and operated by GFZ Potsdam, Germany. Jurisdiction: Single jurisdiction (Germany).
5.3 Re-anchoring and Validation of Published Risk Findings
| Original Finding & Risk Type | Current WA2 Attachment | Re-anchored Granular Function | Validation Status & Sourced Evidence Update |
|---|---|---|---|
| Absence of Confirmed GRACE-FO Successor (Mission-Continuity SPoF / WA3 Gap 6) | Attached to F0 (Gravity Data Acquisition) | Re-anchored to F1 (Satellite Gravimetry Space Mission Operations) | Corroborated. GRACE-FO operates beyond its nominal baseline lifetime. Any mission gap before a successor (e.g. GRACE-C / MAGIC) is launched directly halts continuous monthly time-variable gravity solutions, degrading downstream monitoring of ice sheets and groundwater. Sourced: GGOS EGV White Paper V7.0; NASA/GFZ. |
| Surface Gravity Distribution Gaps & Data Siloing (Geographic / Interoperability Risk) | Attached to F0 (Acquisition) & F1 (Archiving) | Re-anchored to F2 (Surface Acquisition) and F3 (Dual-Stream Archiving) | Corroborated. Extensive regions of Africa, South America, and oceans lack ground gravity measurements. A large volume of historical data remains privately held by resource extraction firms or classified by defense agencies, preventing open FAIR access. Sourced: BGI; State of Geodesy 2026, Data Sharing baseline. |
| Contracting Ultra-High-Degree Modeling Pool (Succession / Knowledge Concentration) | Spanned across F2 and F3 | Re-anchored to F7 (Ultra-High-Degree Global Gravity Field Combination) | Corroborated & Deepened. Producing degree-2190 models (EGM2008, XGM2019e) is restricted to a small cohort of scientists at NGA, GFZ, and TU Munich. Retiring specialists are not being replaced at needed rates; Training & Education is scored 1.25 and Knowledge Management 1.25. Sourced: State of Geodesy 2026. |
| ICGEM Single-Institution Funding Vulnerability (Governance & Continuity Risk) | Attached to F4 (Validation & Distribution) | Re-anchored to F9 (Model Archiving & Dissemination) | Corroborated. ICGEM is the sole authoritative global clearinghouse for gravity field models and online calculation services. It operates entirely on GFZ institutional funding with no binding intergovernmental SLA or multilateral trust fund. Sourced: ICGEM Annual Reports; IGFS. |
| JPL Campus Disruptions (Institutional / Workforce Stress) | Noted in Tier 1–2 narrative | Re-anchored to F3 (PO.DAAC) and F4 (JPL SDS) | Corroborated & Updated. NASA JPL hosts PO.DAAC and constitutes one of the three primary GRACE-FO analysis centres. JPL sustained ~25% workforce layoffs in 2024–2025 and a 6-day disruption during the Jan 2025 wildfires. Sourced: SpaceNews; Greenbelt News Review (2025). |
5.4 New Material Findings Not Currently Captured in WA2
- Operational Maturation of COST-G for Time-Variable Gravity: The IAG Combination Service for Time-variable Gravity Fields (COST-G, hosted at AIUB) is now a fully mature operational combination service (F5) providing standardized, multi-centre monthly time-variable solutions. Separating F5 from static high-degree geoid combination (F7) is essential because COST-G operates on an ongoing monthly cadence with institutional multi-centre redundancy, whereas static geoid combination operates on a decade scale with acute institutional concentration.
- Upcoming GRACE-C / MAGIC Mission Architecture: NASA and ESA/DLR have formalized plans for the GRACE-C (NASA/DLR) and MAGIC (Mass Change and Geosciences International Constellation, ESA/NASA) missions targeted for the late 2020s. While funding commitments have advanced, the launch schedule remains tight relative to GRACE-FO's aging propellant and battery margins, maintaining F1 as a high-watch continuity risk.
5.5 Sourced References for Global Earth Gravity Field
- Förste, C., et al. (2019). "XGM2019e: a new global combined gravity field model up to degree and order 2190." GFZ Data Services, DOI: 10.5880/ICGEM.2019.007.
- Ince, E. S., et al. (2019). "ICGEM – 15 years of successful service and development for the global gravity field community." Journal of Geodesy, 93(11), 2077–2095.
- Jäggi, A., et al. (2020). "COST-G: The International Combination Service for Time-variable Gravity Fields." Advances in Geosciences, 50, 45–54.
- Pavlis, N. K., et al. (2012). "The development and evaluation of the Earth Gravitational Model 2008 (EGM2008)." Journal of Geophysical Research: Solid Earth, 117(B4).
- UN-GGCE (2026). State of Geodesy 2026: A Baseline Maturity Assessment, United Nations Global Geodetic Centre of Excellence, Bonn.
6. Synthesis and Comparative Architectural Findings Across All 5 Products
Across all five critical geodetic products, decomposing the supply chains into their real, granular operational functions reveals structural patterns that were previously concealed under the five-tier taxonomy:
- Convergence on Real Function Granularity:
- EOP: 9 Functions ($F_1 \dots F_9$, with $F_{7a}$ Rapid and $F_{7b}$ Final combinations distinguished).
- Satellite Orbits: 7 Functions ($F_1 \dots F_7$).
- ITRF: 9 Functions ($F_1 \dots F_9$, explicitly exposing Local Tie Surveys and Independent Validation).
- ICRF: 8 Functions ($F_1 \dots F_8$, explicitly exposing Media Logistics and Astrophysical Quality Assurance).
- Global Gravity Field: 9 Functions ($F_1 \dots F_9$, explicitly separating Time-Variable COST-G from Static Geoid modeling).
- The Archiving vs. Correlation Split:
- In all three VLBI-dependent products (EOP, ITRF, ICRF), correlation has been separated from data archiving. Archiving (CDDIS, IGN, SIO, BKG) is a storage/equalization function spanning two jurisdictions; correlation (Washington, Bonn, Haystack) is a high-performance computing bottleneck with an inventory of fewer than ten geodetic-grade facilities globally.
- The Observation vs. First-Mile Telemetry Split:
- Physical sensor maintenance at observatories (antennas, masers, lasers) has distinct failure modes and workforce requirements from network telemetry (e-VLBI transport, NTRIP streaming, ODC pushes). Isolating telemetry exposes the acute Northern Hemisphere concentration of data ingestion nodes (e.g. all three primary GNSS ODCs sit in Germany, France, and the USA).
- Resolution of Single-Jurisdiction Dependencies:
- In EOP, the rapid track ($F_{7a}$, USNO) and definitive track ($F_{7b}$, SYRTE) each operate as single-institution, single-jurisdiction bottlenecks with no cross-track automated failover.
- In Satellite Orbits, the combination engine ($F_5$, SPOCC) remains a software monoculture at GFZ Potsdam, while the ACC leadership transition to Geoscience Australia and NASA GSFC re-exposes the administrative lead to U.S. federal appropriations lapses.
- In ITRF, the official combination ($F_7$, CATREF) is a single-institution software and key-person concentration at IGN (France). The parallel solutions from DGFI-TUM (DTRF) and NASA JPL (JTRF) are essential scientific cross-validators ($F_8$), but currently hold no mandate for operational replacement.
- Readiness for WA2 and Annex Updates:
- These findings provide the complete, sourced, and evidence-verified basis required to update
outputs/2_product_mapping_report.mdand the five product workflow annexes, aligning them with the UN-GGCE Head of Office's BIZBOK metamodel ahead of formal submission.
- These findings provide the complete, sourced, and evidence-verified basis required to update