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International Terrestrial Reference Frame Supply Chain
EGV (Essential Geodetic Variable) Level: 3 — Global · Geometric/Physical | Date: September 2026 | Version: 5.1
Reference: EGV White Paper V7.0 (GGOS — Global Geodetic Observing System, January 2026) · Guiding Principles v4.6 · 1st Joint Development Plan
Major revisions:
- v5.1 — Replaced two raw filename references (the v5.0 entry below, and the
[^ivs-unaffected]footnote) with working links 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.
- v3.9 — Renamed the capability tables' "Risk" column to "Horizon" (it held Horizon 1/2/3 tags, a different concept from the tier-level Risk labels used in the prose); resolved a timing contradiction between Tier 1 and Tier 2 over the ACC's jurisdictional composition.
- v4.1 — Incorporated previously-unaddressed Russia-Ukraine and 2025–2026 disruption evidence into the Tier 0–4 narrative and Evidence Trail; corrected a double-counted capability (Confirmed count 23 → 16 of 23).
- v4.2 — Corrected a misidentification of the three Global Data Centres (IGN had been called a Regional Data Centre), two cross-references citing the wrong tier, and a workflow diagram with an orphaned node and a missing Global Data Centre.
- v5.0 — Converted from the retired five-tier structure to nine real functions (F1...F9), following Work Assignment 2 v5.0's precedent and the same external validation pass checked against primary sources (full findings). Tier 0 split into F1 (Multi-Technique Ground Tracking) and F2 (Co-Location Local Tie Surveys) — the prior bundling obscured that local ties are one of the largest systematic error sources in ITRF realisation, not a footnote inside raw acquisition. F3 (First-Mile Telemetry) is newly separated out of what Tier 1 previously called "archiving" — Network Operations moves here, matching the pattern already established for Satellite Orbits. Tier 1's remainder becomes F4 (Global Archiving & Synchronization). Tier 2 split into F5 (VLBI Correlation & Delay Extraction, carrying Geodetic Software and Tools) and F6 (Intra-Technique Analysis, carrying the four techniques' processing capabilities plus Local Tie Processing and Analysis) — the prior bundling obscured that VLBI correlation is a distinct, severely constrained computing bottleneck sitting upstream of technique analysis, not part of it. Tier 3 becomes F7 (ITRS Combination & Stacking at IGN/CATREF). Tier 4 split into F8 (Independent Cross-Validation — DGFI-TUM's DTRF, NASA JPL's JTRF) and F9 (Formal Designation & Dissemination). Matching Work Assignment 2 v4.0/v6.0's own 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's Annex A.2 correction) — Equipment Calibration and Maintenance's Data dimension (the only N/A dimension among this annex's capabilities) is now excluded rather than scored 0, raising its displayed average from 2.50 to 3.33. Also corrected a pre-existing inconsistency between this document's frontmatter version (previously 4.4) and its body header (previously 4.1) — both now read the same number.
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 the International Terrestrial Reference Frame (ITRF) 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
The International Terrestrial Reference Frame (ITRF) is the Terrestrial Reference Frame (TRF) realisation of the Level 3 Essential Geodetic Variable "Global Reference Frames" in the GGOS EGV framework. It is the foundational product of global geodesy, providing the stable coordinate system that satellite navigation, Earth observation, and critical climate science applications — including sea-level monitoring and crustal deformation analysis — depend on. The authority for its governance and designation rests with the International Earth Rotation and Reference Systems Service (IERS), operating under the joint auspices of the International Astronomical Union (IAU) and the International Union of Geodesy and Geophysics (IUGG).
The ITRF is a combined product derived from observations collected by four distinct space geodetic techniques. These are: the Global Navigation Satellite System (GNSS) network, comprising approximately 500 or more continuous tracking stations; Very Long Baseline Interferometry (VLBI), employing approximately 40 radio telescopes globally; Satellite Laser Ranging (SLR), with approximately 40 laser ranging stations; and the Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) system, supported by approximately 60 ground beacons. Each technique contributes unique and non-substitutable geodetic information: SLR defines the origin (geocentre) and contributes to scale; VLBI independently defines scale and the celestial reference frame tie; GNSS and DORIS provide dense, globally distributed station positions. No single technique can substitute for another in the combination.
A critical structural feature of the ITRF supply chain is a circular dependency with the Level 3 EGV "Satellite Orbits." The ITRF is simultaneously a consumer of precise satellite orbit products — which are required to process GNSS station observations — and an essential prerequisite for their production, since orbit determination itself requires a stable reference frame. A sustained failure in either pipeline degrades the other, ultimately undermining the entire reference frame underpinning all geodetic products globally. The ITRF combination process also co-produces Earth Orientation Parameters (EOP), which connect the terrestrial and celestial reference frames and are essential for all satellite operations.
Co-Produced EGVs
| EGV | Level | Mechanism |
|---|---|---|
| Earth Orientation Parameters | 3 | Consistent EOPs are determined as part of the ITRF solution stacking process |
Governance
| Institution | Role | Risk Level |
|---|---|---|
| IERS Directing Board | Strategic control and official designation of ITRF realisations | Low |
| IERS Central Bureau (BKG — Bundesamt für Kartographie und Geodäsie, the Federal Agency for Cartography and Geodäsie, Germany) | Administrative coordination | Low |
| ITRS Product Center (IGN — Institut national de l'information géographique et forestière, the French national mapping agency; France) | Official computation of the ITRF using CATREF software | High |
| DGFI-TUM (Deutsches Geodätisches Forschungsinstitut der Technischen Universität München, the German Geodetic Research Institute at the Technical University of Munich; Germany) | Independent DTRF realisation for validation | Medium |
| NASA Jet Propulsion Laboratory (JPL, USA) | Independent JTRF realisation for validation | 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 — Multi-Technique Ground Tracking
Data level: Basis — Geodetic Infrastructure. The four-technique ground network (GNSS, VLBI, SLR, DORIS) constitutes the Geodetic Infrastructure Basis EGV under EGV V7.0. Raw observations at this function become Level 1 EGV (Geodetic Observations) upon ingestion to agreed standards.
The global multi-technique ground network is the physical foundation upon which the entire ITRF supply chain rests. Approximately 500 or more GNSS continuous tracking stations, 40 VLBI radio telescopes, 40 SLR laser ranging stations, and 60 DORIS ground beacons collectively provide the raw observations from which the ITRF is ultimately derived. These networks are operated by a diverse set of national mapping agencies, space agencies, and research institutes across Member States, functioning largely on a voluntary, best-effort basis with no binding service level agreements governing station uptime, data quality, or delivery cadence. This structural arrangement, while it has produced a scientifically productive international collaboration, is not consistent with the formal operational commitments expected of critical geodetic infrastructure — specifically the transition from best-effort contributions to formalised SLAs, which (Principle 3: Centralised Accountability through Multilateral Governance) recommends.
Geographic disparities in the distribution of observatories represent a persistent systemic concern. Dense station coverage in Europe and North America contrasts sharply with sparse coverage across Africa, the Pacific, and polar regions — a direct gap against (Principle 1: Geographic Distribution for Technical Performance) and JDP Objective 1.2. This non-uniform distribution introduces regional weaknesses in the combined ITRF solution, particularly in the estimation of geocentre motion and vertical land movement in underserved regions. Aging VLBI and SLR infrastructure compounds this problem: many stations operate with legacy hardware, constrained maintenance budgets, and limited workforce succession planning, creating a slow degradation in the quality and reliability of observations that is difficult to detect without systematic global network monitoring.
The Russia-Ukraine conflict, beginning February 2022, is a documented instance of geopolitical disruption to this ground network. The International DORIS Service formally decommissioned two Russian DORIS beacons in May 2022 (Krasnoyarsk and Yuzhno-Sakhalinsk) and reported a third, at Badary, shut down "at Russia's request," describing the result in a dedicated 2022 workshop presentation as "a hole in DORIS coverage" in high-latitude Eurasia — a region the geographic disparity described above already identifies as under-instrumented.[^ids-2022] Separately, peer-reviewed research documents an approximately 10% reduction in operationally active Ukrainian GNSS stations following the invasion; the same research finds no primary evidence of a resulting impact on ITRF combination products.[^ukraine-gnss] The techniques were affected unevenly: Russian VLBI stations (Zelenchukskaya, Badary, Svetloe) remained listed as active throughout 2022–2024, with no IGS- or IVS-level network notices issued regarding either Ukrainian or Russian stations.[^ivs-unaffected] A parallel, narrower disruption affected Satellite Laser Ranging: the ILRS Governing Board documented in April 2022 that member stations had "essentially halted the flow of GLONASS data since the beginning of March," through a combination of stations no longer observing GLONASS and stations withholding data from ILRS Data Centres.[^ilrs-glonass] The tracking withheld was specific to GLONASS; ITRF's SLR technique consumes tracking of core geodetic satellites (principally LAGEOS) for origin and scale definition, and no primary source confirms a withholding of that ITRF-input SLR data.
Under EGV framework V7.0, the four-technique ground network is explicitly recognised as a Geodetic Infrastructure Basis EGV — a formal acknowledgement that this distributed physical asset is an EGV-level resource in its own right, warranting commensurate governance and investment.
Risk: Medium — The network operates on best-effort institutional arrangements with significant geographic disparities and aging infrastructure; no formal SLAs govern station uptime or data delivery. The absence of formalised national backing for aging VLBI and SLR infrastructure is a direct gap against (Principle 5: Minimum Capability Maturity).
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| 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 |
| SLR Data Acquisition and Storage | 2.00 | 4.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
| 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 |
| DORIS Data Acquisition and Storage | 4.00 | 4.00 | 4.00 | 4.00 | 4 of 4 | 4.00 |
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F2 — Co-Location Local Tie Surveys
Data level: Basis → Level 1 EGV transition. Local tie surveys are terrestrial measurements, not space geodetic observations, but they are the physical link that makes the four-technique network usable as one combined solution.
A particularly important element of this supply chain is the conduct of local tie surveys at co-located sites — geodetic monuments where two or more techniques observe from the same physical location. These surveys, which are terrestrial measurements linking the reference points of different instrument types, are the critical connective tissue between the four technique networks. Any error or inconsistency in a local tie measurement propagates directly into the ITRF combination, introducing biases that are practically impossible to separate from genuine geophysical signals.
Risk: Medium — Local tie surveys are conducted on a best-effort, campaign basis with no formal recurring schedule or funded programme; discrepancies between terrestrially surveyed local ties and space-geodetic-implied values are among the most technically challenging aspects of the ITRF combination process, described further at F6 and F7 below.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Local Tie | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F3 — First-Mile Telemetry & Data Transport
Data level: Basis → Level 1 EGV transition. The transmission link between a station and its archiving destination is where a raw observation becomes a delivered, archivable data stream.
Raw observations from F1's ground network are transmitted to the archiving layer (F4) via technique-specific pathways: e-VLBI broadband transfer for time-critical VLBI sessions, near-real-time push for GNSS, and scheduled uploads for SLR and DORIS. This first-mile connection is a distinct operational layer from both the physical tracking network (F1) and the archiving destination (F4) it feeds.
Risk: Medium — Network Operations' Technology dimension scores at the low end of the scale across this document, reflecting the absence of automated failover and formal monitoring infrastructure at the transmission layer — the same underlying capability gap documented in more detail at F4, below, where its organisational consequences are more fully evidenced.
| 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, re-verified against the live capability-maturity graph 2026-08-29)
F4 — Global Archiving & Synchronization
Data level: Level 1 EGV (Geodetic Observations) — standardised observation files (RINEX, SINEX) ingested and mirrored across global data centres.
Observations transmitted via F3 are ingested, standardised, and stored in a network of three Global Data Centres (GDCs). The primary global custodian is the Crustal Dynamics Data Information System (CDDIS), operated by NASA's Goddard Space Flight Center (GSFC); the Institut national de l'information géographique et forestière (IGN, France) and the Scripps Institution of Oceanography (SIO, USA) are the other two, and equalization protocols between the three GDCs enable cross-replication to provide a degree of redundancy. Regional Data Centres such as BKG (Germany) sit one layer below the GDCs, playing a distinct supporting role. The CDDIS archive is the principal access point for the technique services at F6, and its continuity is therefore a prerequisite for the entire downstream supply chain.
A structural concentration risk is present at this function. CDDIS and the Scripps Institution of Oceanography (SIO) mirror — the two primary data centres supporting the International GNSS Service (IGS) — are both hosted within the United States. This means the global archiving function for the most critical technique (GNSS) effectively spans only a single political jurisdiction. The 2018–2019 U.S. government shutdown (35 days) demonstrated in operational terms the consequence of this concentration: while CDDIS automated data flow continued, manual curation and U.S. Analysis Centre contributions were suspended, and the overall supply chain remained functional only because the IGS's Analysis Center Coordinator (ACC) was, at the time, co-led by Geoscience Australia and MIT — neither a U.S. federal body — and so sat outside U.S. federal jurisdiction. (Source: IGS 2018 Technical Report; see the Satellite Orbits Workflow annex, F5, for detailed sourcing of this event.) That composition has since changed; F6 below sets out why the risk this event illustrates has re-emerged. The current arrangement is inconsistent with (Principle 2: Political Resilience and Distributed Operational Control), which recommends that critical supply chain functions not be concentrated within any single political jurisdiction. (Principle 4: Technical Interoperability and Data Accessibility) further recommends that FAIR-compliant data access and verifiable interoperability be maintained across all archiving centres. A longitudinal review of IGS Technical Reports has also documented repeated failures by major GDCs to submit annual operational reports, reflecting a systemic gap in network monitoring and administrative accountability that corresponds directly to the low maturity score observed in the Network Operations capability (F3) — and constitutes a failure against (Principle 6: Transparency, Monitoring and Performance Assurance).
The equalization protocol between CDDIS, IGN, and SIO is architecturally designed to provide resilience against a single GDC-site failure, and this mechanism has been invoked at least once: in 2007, following a CDDIS hardware fault, the CDDIS manager directed users to the IGN and SIO mirrors by name.[^cddis-2007] However, no deliberate failover drill, disaster-recovery exercise, or business-continuity test of the protocol appears anywhere in the IGS Technical Reports or the IGS mailing list archive, and no documented instance of an Analysis Centre switching from CDDIS to IGN or SIO was found during either of the two confirmed CDDIS-affecting shutdowns covered in this assessment (2013, 2018–2019).[^gdc-failover-search] A further, more specific risk to CDDIS continuity has since materialised: NASA GSFC, CDDIS's host institution, sustained a reduction of approximately 32% of its civil servant workforce through DOGE-related actions from February 2025 onward, and the U.S. government shutdown of 1 October–12 November 2025 (42 days) furloughed the GSFC staff sustaining CDDIS during the same period.[^gsfc-2025] No CDDIS service outage notice was issued during either event, consistent with the automated-flow resilience observed in 2013 and 2018–2019; the resulting effect on manual curation and quality-oversight capacity at CDDIS cannot be confirmed either way. See the Satellite Orbits Workflow annex, F5, for the fuller account of this compounded 2025-2026 disruption across the US-hosted IGS infrastructure it shares with this function. This is an absence of evidence: it means the redundancy has not been demonstrated under the disruption conditions this assessment is concerned with. No equivalent disclosure exists for CDDIS, IGN, or SIO themselves; the closest documented parallel is one layer below the GDCs — BKG, a Regional Data Centre, has openly reported having no disaster-recovery capability at all[^bkg-no-dr] — which is suggestive of the wider institutional posture around GDC-adjacent infrastructure.
Risk: Medium — High dependency on CDDIS and U.S. institutional stability; the GDC network spans only two political jurisdictions, conflicting with (Principle 2: Political Resilience and Distributed Operational Control). The equalization protocol's failover to IGN/SIO is architecturally real but operationally unverified — no drill or documented use during a disruption was found, and BKG — an adjacent Regional Data Centre, not one of the three GDCs — has openly reported having no disaster-recovery capability of its own, the closest documented parallel available.[^bkg-no-dr]
| 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)
F5 — VLBI Correlation & Delay Extraction
Data level: Level 1 (intermediate) — correlated interferometric observables (group delays), not yet a station-position solution.
VLBI processing carries a distinct throughput bottleneck at the correlation stage, upstream of and structurally separate from the per-technique analysis described at F6. Unlike GNSS and DORIS, which process data in near-real time, VLBI correlation is computationally intensive and operationally constrained by the limited number of active correlators and the data volume generated by modern wideband VLBI systems — principally Washington (NASA GSFC/USNO, USA), Bonn (Max Planck Institut für Radioastronomie/BKG, Germany), and Haystack (USA). This bottleneck is a structural throughput constraint for the IVS combination and ultimately for the ITRF combination cadence.
Risk: High — A small number of globally available correlator facilities concentrated in two jurisdictions (USA, Germany) constrain VLBI throughput for the entire ITRF pipeline; no rapid substitute pathway exists if a major correlator is disrupted.
| 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, re-verified against the live capability-maturity graph 2026-08-29)
F6 — Intra-Technique Analysis
Data level: Level 1 → Level 2 (intermediate) — technique-specific combined solutions (SINEX files with station positions, velocities, EOPs) from each technique service.
Archived and correlated data is retrieved and processed by the four international technique services, each of which coordinates a network of Analysis Centers (ACs) to produce intra-technique combined solutions. The IGS is coordinated by its Central Bureau at JPL; its combined GNSS SINEX files are produced through its ACC, which is transitioning from Geoscience Australia/MIT co-leadership to Geoscience Australia/NASA GSFC co-leadership (full operational capability expected late 2025). This transition is the reason the jurisdictional risk noted at F4 has re-emerged: the earlier Geoscience Australia/MIT composition sat entirely outside U.S. federal jurisdiction — Geoscience Australia is Australian and MIT is a private U.S. university — which is why it remained unaffected by the 2018–2019 U.S. government shutdown; the current/transitioning Geoscience Australia/NASA GSFC composition reintroduces that risk, because NASA GSFC is itself a U.S. federal facility. The International VLBI Service for Geodesy and Astrometry (IVS) is coordinated by NASA GSFC; its Analysis Centers process the correlated delays from F5 to produce VLBI SINEX files. The International Laser Ranging Service (ILRS) is coordinated by NASA GSFC and produces SLR SINEX files. The International DORIS Service (IDS) is coordinated by CNES and produces DORIS SINEX files.
NASA GSFC's coordination of both the IVS and ILRS technique services extends the 2025 workforce reduction described at F4 beyond CDDIS archiving capacity, to two of the four technique services this function depends on. The IGS Central Bureau at JPL sustained a comparable reduction over the same period — approximately 25% of its total workforce lost across four rounds of layoffs, 2024–2025 — and, separately, a six-day network and power disruption during the January 2025 Los Angeles wildfires; NOAA/NGS, one of the Analysis Centres contributing to the GNSS technique service, lost more than 25% of its staff over the same period.[^jpl-2025] No product delivery failure attributable to any of these events has been documented for any of the four technique services at this function.
Each technique service employs multiple Analysis Centers using diverse and independently developed software packages — including Bernese, GipsyX, NAPEOS, PANDA, and EPOS.P8 for GNSS — to mitigate algorithmic bias and validate solution consistency through cross-comparison. This software diversity provides a degree of algorithmic resilience at the AC layer. However, this resilience coexists with a knowledge fragility: the teams maintaining these specialised software packages are typically small academic groups operating with limited succession planning, and in several cases the expertise is concentrated in a single institution or a small number of individuals. The departure of key personnel from these teams would represent a significant operational risk.
Local tie surveys collected at F2 are also a critical input at this function. The technique-specific SINEX files produced by each service must be linked through the local tie measurements established at co-located observatories before they can be meaningfully combined at F7. Discrepancies between the local tie values used by different services, or inconsistencies between terrestrially surveyed local ties and those implied by the space geodetic data, are among the most technically challenging aspects of the ITRF combination process.
Risk: High — Knowledge fragility and reliance on specific human capital across all four technique services. The small, undocumented specialist teams maintaining key software packages violate the workforce resilience requirements of (Principle 5: Minimum Capability Maturity).
| 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 |
| VLBI Data Processing and Analysis | 2.00 | 2.00 | 2.00 | 3.00 | 4 of 4 | 2.25 ⚠ |
| SLR Data Processing and Analysis | 3.00 | 4.00 | 3.00 | 4.00 | 4 of 4 | 3.50 |
| DORIS Data Processing and Analysis | 4.00 | 4.00 | 3.00 | 4.00 | 4 of 4 | 3.75 |
| Local Tie Processing and Analysis | 2.00 | 3.00 | 1.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
Note on this table: Local Tie Processing and Analysis is shared with F7's table below — the same underlying score applies to both functions, not a duplicated assessment.
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F7 — ITRS Combination & Stacking (IGN/CATREF)
Data level: Level 3 EGV (Global Reference Frames — ITRF realisation) — the official ITRF, the fundamental global coordinate system.
The four technique-specific combined SINEX files, together with local tie survey data and Earth orientation series, are ingested at this function by the ITRS Product Center at IGN (France) to produce the unified ITRF. This is the critical hub of the entire ITRF supply chain. The computation is performed using CATREF, a proprietary software package developed and maintained in-house at IGN. CATREF implements a rigorous stacking of time series of station positions and EOPs from all four techniques, applying a datum definition in which: the origin is defined by SLR (which provides the most direct and stable connection to the Earth's centre of mass); scale is defined by VLBI and SLR jointly; and orientation is constrained by a no-net-rotation condition relative to the previous ITRF realisation. The simultaneous estimation of technique-specific biases and the adjudication of local tie discrepancies requires expert scientific judgement that cannot be automated without loss of product integrity.
The core scientific team responsible for ITRF combination — led by Dr. Zuheir Altamimi, ITRF combination lead, IGN — is small and possesses expertise that is highly concentrated and not readily transferable. The combination process requires iterative adjudication of station discontinuities, outlier handling, and local tie weighting decisions that draw on decades of accumulated institutional knowledge. CATREF, as a proprietary in-house software package, is not openly documented or maintained by an independent community, creating a succession risk that extends beyond personnel to the computational toolchain itself. The departure of key individuals without structured knowledge transfer and software documentation would constitute a critical supply chain disruption.
Risk: High — Production relies on a small, stable core team at IGN with concentrated expertise; CATREF software is proprietary and in-house; key-person risk is acute. The concentration of this critical function in a single institution with no formal backup mandate is inconsistent with (Principle 2: Political Resilience and Distributed Operational Control) and (Principle 5: Minimum Capability Maturity). The absence of an independent community software implementation means that even (Principle 4: Technical Interoperability and Data Accessibility) — which recommends that data and processing workflows can be redistributed without degradation — cannot be verified.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Knowledge Management | 1.00 | 2.00 | 1.00 | 1.00 | 4 of 4 | 1.25 ⚠ |
| Local Tie Processing and Analysis | 2.00 | 3.00 | 1.00 | 2.00 | 4 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 |
(Source: State of Geodesy 2026, re-verified against the live capability-maturity graph 2026-08-29)
F8 — Independent Cross-Validation
Data level: Level 3 EGV (pre-designation) — independent parallel realisations used to verify the IGN candidate solution before formal adoption.
Two independent parallel realisations provide an essential validation function. DGFI-TUM (Germany) independently computes the DTRF using its DOGS-CS software, and NASA JPL (USA) independently computes the JTRF using a Kalman filter approach via GipsyX. These independent solutions are compared against the IGN candidate ITRF — through systematic comparison of origin and scale consistency, station position agreement, and EOP series alignment — to identify systematic biases or anomalies before formal designation at F9. While this redundancy strengthens scientific confidence in the final product, neither DGFI-TUM nor JPL has the formal mandate or operational agreement to serve as a substitute for IGN as the ITRS Product Center; they function as validators, not operational backups. JPL's independent JTRF computation depends on the same institutional capacity affected by the 2025 workforce reductions and wildfire disruption described at F6; no delay to JTRF product delivery has been documented as a result.
Risk: Medium — Technically robust through independent validation redundancy, but neither validator holds a formal mandate to substitute for IGN if the ITRS Product Center itself were disrupted.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Regulatory Compliance | 3.00 | 3.00 | 3.00 | 3.00 | 4 of 4 | 3.00 |
(Source: State of Geodesy 2026)
F9 — Formal Designation & Dissemination
Data level: Level 3 EGV (validated Global Reference Frame) — the official ITRF realisation formally designated and distributed.
Following the F8 validation comparison, discrepancies exceeding agreed thresholds are reviewed and adjudicated before the candidate solution is advanced for formal designation. The IERS Directing Board exercises its formal authority at this stage, officially designating the validated solution as the current ITRF realisation. This designation carries international legal and scientific standing and is the authoritative coordinate reference for all UN Member State geodetic activities.
Distribution of the designated ITRF is accomplished through IERS Product Centers and the CDDIS archive, providing SINEX files containing station positions and velocities, as well as Helmert transformation parameters enabling users to relate earlier ITRF realisations to the current solution. The long-term operational stability of this distribution infrastructure depends on voluntary institutional funding commitments from IGN, NASA, and BKG — the primary host institutions. No centralised funding mechanism or binding multilateral agreement currently governs the continued availability of these services, meaning the distribution infrastructure rests on institutional goodwill and national budget continuity.
Risk: Medium — Long-term stability depends on voluntary institutional funding with no formal SLA. (Principle 6: Transparency, Monitoring and Performance Assurance) recommends that distribution infrastructure be backed by published uptime commitments and a formal escalation process.
| Capability | People | Process | Technology | Data | Dimensionality | Avg |
|---|---|---|---|---|---|---|
| Data Distribution | 2.00 | 2.00 | 1.00 | 3.00 | 4 of 4 | 2.00 ⚠ |
| Geodetic Services | 2.00 | 2.00 | 2.00 | 2.00 | 4 of 4 | 2.00 ⚠ |
(Source: State of Geodesy 2026)
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 — 23 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 (16 of 23 capabilities currently in this document):
- F1 (3): Ground-Based Asset Management, Equipment Calibration and Maintenance, [SLR/VLBI/GNSS/DORIS Data Acquisition and Storage counted with F1's table]
- F2 (1): Local Tie
- F3 (1): Network Operations
- F4 (3): Data Quality Management, Metadata Management, Data Preservation
- F5 (1): Geodetic Software and Tools
- F6 (4): GNSS Data Processing and Analysis, DORIS Data Processing and Analysis, SLR Data Processing and Analysis, Local Tie Processing and Analysis
- F7 (2 net new — Local Tie Processing and Analysis shared with F6; Knowledge Management listed separately below): Reference Frames, Geodetic Data Products
- F8/F9 (3): Regulatory Compliance, Data Distribution, Geodetic Services
Asserted — none. Unlike Satellite Orbits, 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 (7 capabilities):
- Knowledge Management (F7, currently 1.25) — the annex's F7 narrative names a specific individual (Dr. Zuheir Altamimi) leading "a small" team with expertise that is "highly concentrated and not readily transferable." This is real, specific evidence — but it describes the same kind of key-person concentration risk the shared baseline's already-low score (People 1.00, Process 2.00, Technology 1.00, Data 1.00) is presumably already responding to across the wider capability model. Left at baseline deliberately — a Technical Product Working Group member closer to IGN's actual staffing could resolve this either way.
- DORIS Data Acquisition and Storage (F1, currently 4.00) — the International DORIS Service formally decommissioned two Russian DORIS beacons in May 2022 (Krasnoyarsk, Yuzhno-Sakhalinsk) and reported a third, at Badary, shut down "at Russia's request," describing the result as "a hole in DORIS coverage" in high-latitude Eurasia.[^ids-2022] This is real, specific, product-relevant evidence of a network-level disruption to one of ITRF's four core techniques — the strongest single piece of unincorporated evidence found in this cross-reference — but assigning it to a specific PPTD dimension requires a judgement this pass does not make. Flagged for the Technical Product Working Group, or a dedicated per-dimension review, ahead of this document's next revision.
- GNSS Data Acquisition and Storage (F1, currently 3.50) — peer-reviewed research documents an approximately 10% reduction in operationally active Ukrainian GNSS stations following the February 2022 invasion.[^ukraine-gnss] The same source finds no primary evidence of a resulting impact on ITRF combination products, which is why this is left at baseline.
- VLBI Data Acquisition and Storage (F1, currently 3.00) and VLBI Data Processing and Analysis (F6, currently 2.25) — Russian VLBI stations remained listed as active throughout 2022–2024, with no IGS- or IVS-level network notices issued regarding either Ukrainian or Russian stations.[^ivs-unaffected] This is reassuring evidence: it corroborates that VLBI's already-low scores in these tables reflect the correlator throughput bottleneck described at F5, not a network-participation gap.
- SLR Data Acquisition and Storage (F1, currently 3.00) and SLR Data Processing and Analysis (F6, currently 3.50) — the ILRS Governing Board documented member stations halting GLONASS data flow to ILRS Data Centres from March 2022.[^ilrs-glonass] This confirms the same member-driven data-withholding mechanism documented for DORIS, applied to the SLR technique. The tracking withheld was specific to GLONASS; ITRF's SLR technique consumes tracking of core geodetic satellites (principally LAGEOS) for origin and scale definition, and no primary source confirms a withholding of that ITRF-input SLR data.
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 — Governance table: "IERS Directing Board — Strategic control and official designation of ITRF realisations." Direct evidence of a named authority, the same kind of evidence Satellite Orbits used to assert its own Mandate departure — not yet scored here.
- Funding and Investment — F9: distribution infrastructure "depends on voluntary institutional funding commitments from IGN, NASA, and BKG... No centralised funding mechanism or binding multilateral agreement currently governs the continued availability of these services."
- Legal Framework — the same F9 sentence ("no binding multilateral agreement") is also direct evidence for this capability; whether it belongs under Funding and Investment, Legal Framework, or both is a judgement call left open here.
- Training and Education — F6 ("limited succession planning" across AC software teams) and F7 ("not readily transferable" expertise at IGN) both speak to this capability directly, as do the 2025 DOGE-related workforce reductions described at F4 and F6 (approximately 25%+ of staff at NOAA/NGS, 32% of civil servants at NASA GSFC, and 25% of the total workforce at JPL across four rounds).[^gsfc-2025][^jpl-2025] ITRF has no Training and Education row in any function table currently, unlike ICRF and Gravity, which do.
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 |
|---|---|---|
| ITRS Product Center at IGN (F7) | Sole official custodian; proprietary CATREF software; key-person risk around core team | 1.4 — Succession planning for specialised expertise |
| Local tie surveys (F2, F6, F7) | Best-effort campaigns; discrepancies propagate into combinations | 1.1 — Formalised operational agreements |
| VLBI/SLR infrastructure (F1) | Aging and degrading networks; threatens scale and origin definition | 1.3 — Formalised national backing for critical capabilities |
| VLBI correlator capacity (F5) | Small number of facilities in two jurisdictions; throughput bottleneck | 1.2 — Political distribution of critical functions |
| Independent realisations (DTRF, JTRF) (F8) | Maintained voluntarily with no formal funding SLA | 1.1 — SLAs and MoUs for critical functions |
| GDC political distribution (F4) | Only USA and France host GDCs; two political jurisdictions | 1.2 — Political distribution of critical functions |
[^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 [^ids-2022]: International DORIS Service, DORIS News (May 2022), https://ids-doris.org/doris-news.html; Chauveau (CLS), "Impact of the Russia-Ukraine war on the DORIS network," IDS Workshop 2022, https://ids-doris.org/resources/presentations/ids-meetings/i03-2022-3654.html [^ukraine-gnss]: Main Astronomical Observatory, National Academy of Sciences of Ukraine, Kinematics and Physics of Celestial Bodies (2024), processing 273 Ukrainian GNSS stations across GPS weeks 2106–2237 (May 2020 – November 2022), https://link.springer.com/article/10.3103/S0884591324010057 [^ivs-unaffected]: Verified against the Reference Verification register (UN-GGCE internal evidence register), §4, "What Was NOT Disrupted." No dedicated primary-source notice was found confirming this specific claim; recorded here at the same confidence level as the source document. [^ilrs-glonass]: ILRS Governing Board statement (19 April 2022), as reported in Navigation Outlook via RNTF (May 2022), https://rntfnd.org/2022/05/02/laser-ranging-data-essential-to-russian-glonass-system-dries-up-after-attack-on-ukraine-navigation-outlook/; IAG Statement on Ukraine (3 March 2022), https://igs.org/news/iag-statement-on-ukraine/ [^cddis-2007]: International GNSS Service, 2007, IGSMAIL-5600 "CDDIS server down", https://lists.igs.org/pipermail/igsmail/2007/006971.html [^gdc-failover-search]: Search of the IGS Technical Reports (2013, 2018, 2019) and the IGSMAIL pipermail archive (2013, 2018–2019 date ranges) for failover drills, contingency exercises, and Analysis Centre reports of switching from CDDIS to IGN or SIO during a disruption. None found. No public usage or access statistics exist for CDDIS, IGN, or SIO that would independently confirm whether traffic shifted between centres during either event. [^bkg-no-dr]: International GNSS Service, IGS 2018 Technical Report, p. 159: "A disaster recovery system for the GDC is not installed and not scheduled currently" (BKG Regional Data Center report — BKG is one of the network's RDCs, not one of the three GDCs), https://files.igs.org/pub/resource/technical_reports/2018_techreport.pdf [^gsfc-2025]: NASA Goddard Space Flight Center workforce reduction (~32% of civil servants) via DOGE-related actions from February 2025 (Space.com; Greenbelt News Review); U.S. government shutdown of 1 October–12 November 2025 (42 days), NASA Shutdown Page, https://www.nasa.gov/shutdown/; The Planetary Society, 12 November 2025, https://www.planetary.org/articles/nasa-is-funded-now-what [^jpl-2025]: NASA JPL workforce reduction (~25% of total workforce across four rounds, 2024–2025): SpaceNews; CalTech; LAist. JPL wildfire disruption (January 2025, six days): IGSMAIL-8553 https://lists.igs.org/pipermail/igsmail/2025/008549.html, IGSMAIL-8555 https://lists.igs.org/pipermail/igsmail/2025/008551.html. NOAA/NGS workforce reduction (25%+ by May 2025): Wired, 21 May 2025; PBS NewsHour.