TL;DR
Researchers found that earlier versions of two Snowden-derived PDF guides contained detailed descriptions of U.S. National Reconnaissance Office (NRO) Mission Ground Stations that were deleted before publication. The deletions are visible in embedded PDF version metadata and show classified operational designations and layered cover names for domestic sites.
What happened
Analysis of PDF version metadata in two documents published alongside investigative stories in 2016 and 2017 showed that substantive sections about U.S. ground stations were present in earlier file versions but absent in the publicly released PDFs. The documents—identified in the reporting as a Menwith Hill classification guide and an NRO SIGINT guide for Pine Gap—contained hidden text in their internal version histories naming operational designations and listing cover names, visitor details, and classification markings. Among the removed items were the operational labels Potomac Mission Ground Station (PMGS) tied to buildings 259 and 260 at the Naval Research Laboratory in Washington, D.C., and Consolidated Denver Mission Ground Station (CDMGS) at Buckley Space Force Base (publicly known as Aerospace Data Facility, ADF). Equivalent sections for foreign facilities such as RAF Menwith Hill and Pine Gap appear to remain unaltered in the published documents. The embedded metadata therefore provides forensic evidence that content was deleted rather than simply redacted.
Why it matters
- The discovery shows that internal PDF version history can retain deleted classified content even when visible pages are sanitized for publication.
- It highlights a deliberate classification scheme separating public cover names from secret operational designations for U.S. ground stations.
- The pattern—detailed domestic sections removed while foreign facility descriptions remained—raises questions about how domestic intelligence infrastructure is documented and disclosed.
- For news and oversight, the finding points to a technical avenue (file metadata analysis) for recovering previously suppressed information.
Key facts
- The reporting is based on embedded version metadata in two PDFs associated with Snowden-derived documents published with investigative stories in 2016 (The Intercept) and 2017 (The Intercept and Australian Broadcasting Corporation).
- Earlier PDF versions contained text later removed from the visible files; that text remains in the files' internal version histories.
- Removed domestic operational designations include Potomac Mission Ground Station (PMGS) and Consolidated Denver Mission Ground Station (CDMGS).
- Public cover names tied to those sites in the hidden text include Classic Wizard Reporting and Testing Center (CWRTC) / Mission Support Facility (MSF) for PMGS, and Aerospace Data Facility (ADF) for CDMGS.
- The hidden PMGS entry includes visitor-location detail: buildings 259 and 260 at the Naval Research Laboratory in Southwest Washington, D.C.
- Classification markings in the deleted text (e.g., S//TK) indicate some associations and even the fact of a cover story were treated as classified.
- Foreign facilities such as RAF Menwith Hill and Pine Gap retained their detailed published descriptions in the same guides.
- The guides present a pattern where domestic sites use multiple cover names while foreign sites typically use a single cover name.
- The PDF metadata acts as forensic evidence that the documents underwent edits removing substantive domestic sections prior to publication.
What to watch next
- not confirmed in the source: whether government agencies will comment on who performed the edits or why the domestic sections were excised.
- not confirmed in the source: whether additional Snowden-derived documents contain similar hidden version histories that reveal removed content.
- not confirmed in the source: whether any official review, legal action, or oversight inquiry will follow from this technical finding.
Quick glossary
- PDF metadata: Hidden information embedded in a PDF file that can include document history, versioning, authorship data, and other properties not visible on printed pages.
- Mission Ground Station (MGS): A ground-based facility that supports the control, reception, processing, or dissemination functions for reconnaissance satellites.
- Cover name / cover story: An alternate, often public-facing name or explanation for a facility or activity intended to conceal its true operational purpose.
- S//TK: A marking used in some classification schemes indicating Secret level information with Talent Keyhole handling caveats; precise handling rules vary by agency.
Reader FAQ
Which documents contained the hidden text?
Two classification guides associated with Snowden-derived material are cited: a Menwith Hill satellite classification guide and an NRO SIGINT guide for Pine Gap.
What specific domestic sites were named in the deleted sections?
The removed text identified Potomac Mission Ground Station (PMGS) linked to the Naval Research Laboratory and Consolidated Denver Mission Ground Station (CDMGS) linked to Buckley Space Force Base (Aerospace Data Facility).
Do we know who removed the material from the published PDFs?
not confirmed in the source.
Were foreign facility entries also removed?
No — the source reports that equivalent foreign facility sections (for example RAF Menwith Hill and Pine Gap) remained in the published documents.
Going Through Snowden Documents, Part 4 Published on 10 Jan 2026 Previous parts: Part 1 Part 2 Part 3 We discovered that entire sections describing domestic U.S. intelligence facilities were…
Sources
- New information extracted from Snowden PDFs through metadata version analysis
- Snowden disclosures
- Lifting the Veil on NRO Satellite Systems and Ground …
- NSA files decoded: Edward Snowden's surveillance …
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