In a landmark demonstration of allied cooperation in space domain awareness (SDA), the United States Space Force (USSF) maneuvered one of its Geosynchronous Space Situational Awareness Program (GSSAP) satellites to observe a United Kingdom military satellite in geosynchronous orbit. The operation marks the first known instance of an American satellite conducting an on-orbit inspection of an allied nation’s spacecraft by request—signaling new levels of transparency and interoperability among close partners in the increasingly contested space domain.
First Allied On-Orbit Observation Maneuver
The maneuver took place earlier this year and involved repositioning one of the GSSAP satellites to approach and image the UK’s Skynet 5A satellite. The British Ministry of Defence requested the operation as part of a bilateral effort to deepen collaboration on SDA capabilities. According to U.S. officials, including Lt. Gen. John Shaw (then Deputy Commander of U.S. Space Command), this was “the first time we’ve done rendezvous and proximity operations with an allied satellite.”
The GSSAP constellation is designed specifically for high-resolution observation and characterization of objects in geosynchronous orbit (GEO). By leveraging its ability to perform precise orbital maneuvers and station-keeping near other satellites without causing interference or collision risk, GSSAP provides persistent surveillance that is critical for identifying potential threats or anomalies in GEO—home to many strategic communications and early warning systems.
Strategic Significance for Coalition SDA
This demonstration represents more than just technical capability—it signals growing trust between allies operating in contested orbital regimes. With adversaries such as Russia and China fielding co-orbital inspection satellites that may have dual-use or counterspace functions, transparency among friendly nations becomes vital.
By allowing U.S. assets to inspect its own spacecraft, the UK has shown confidence in both American technical capabilities and intent. Conversely, it allows U.S. operators to refine procedures for cooperative rendezvous with non-hostile targets—a skill set that may prove essential if future coalition operations require servicing or rescue missions involving allied platforms.
- Skynet 5A: A secure military communications satellite launched in 2007 by Airbus Defence & Space under contract with the UK MoD.
- GSSAP: Operated by USSF’s Delta 11 under Space Operations Command; provides unclassified but closely monitored data on object behavior in GEO.
Technical Aspects: GSSAP Capabilities and RPO Protocols
The GSSAP constellation consists of at least four known satellites launched between 2014 and 2020 aboard Delta IV Medium rockets from Cape Canaveral. These spacecraft operate near GEO but can drift slightly above or below the belt using their onboard propulsion systems—allowing them to conduct rendezvous and proximity operations (RPO) without interfering with target satellites’ orbital slots.
The recent maneuver likely involved several key steps:
- Orbital Phasing: Adjusting altitude or inclination slightly to synchronize orbital periods with Skynet 5A.
- Approach & Hold Points: Conducting staged approaches within safe thresholds (typically hundreds down to tens of kilometers).
- Imaging & Characterization: Using optical payloads to collect data on physical condition, orientation, thermal signature or potential anomalies.
This type of RPO requires advanced flight dynamics modeling and constant telemetry monitoring from ground control stations such as those operated by USSF’s National Space Defense Center (NSDC). While specifics remain classified, previous public statements suggest that GSSAP uses electro-optical sensors capable of resolving structural features at close range—critical for anomaly detection or attribution after suspected tampering events.
A Template for Future Multinational SDA Operations
The success of this mission opens doors for similar joint initiatives among other Five Eyes partners (Australia, Canada, New Zealand) or NATO allies seeking enhanced situational awareness over their own orbital assets. With increasing congestion—and threats—in GEO from debris-generating tests like Russia’s Cosmos-1408 ASAT event or shadowing behaviors by Chinese SJ-21-type inspector satellites, collaborative SDA is becoming not just beneficial but necessary.
This mission also aligns with broader policy shifts toward coalition-based defense posture in space. The Combined Space Operations Initiative (CSpO), which includes nine nations as of mid-2024—including France, Germany and Japan—is actively exploring shared architectures for orbital monitoring and threat response coordination.
CSpO Implications
- Shared Data Feeds: Fusion centers may ingest real-time tracking data from national sensors into common operating pictures.
- Tactical Coordination: Allies could coordinate evasive maneuvers if hostile RPOs are detected targeting coalition assets.
- Sovereign Consent Model: Each country retains authority over its own spacecraft but permits partner support under agreed protocols—as demonstrated here with Skynet 5A.
Evolving Legal Norms Around On-Orbit Inspection
This demonstration also touches on evolving international norms regarding proximity operations around foreign-owned space objects. While no binding treaty prohibits peaceful inspection maneuvers conducted with consent—or even without it—the practice remains diplomatically sensitive due to risks of misinterpretation or escalation if perceived as espionage or prelude to attack.
The fact that this was a consensual operation between two close allies sets an important precedent: that transparency can be engineered into SDA practices through bilateral trust-building mechanisms rather than unilateral surveillance alone. It also reinforces calls within UN COPUOS discussions for clearer behavioral norms governing RPOs—including notification thresholds and minimum separation distances—to avoid conflict spirals during tense geopolitical periods.
NATO Context
NATO formally declared space a warfighting domain in December 2019 and continues developing shared doctrine through its Overarching Space Policy framework. This US–UK demonstration could feed into NATO’s evolving concept for collective defense in orbit—especially as more member states launch sovereign military payloads requiring protection from interference or degradation by adversarial actors.
A Step Toward Operational Coalition Resilience in Orbit
The successful execution of this maneuver reflects not only technical maturity but growing political will among Western allies to treat outer space as a shared operational environment—not merely national territory projected upward. As more countries invest heavily into sovereign constellations for C4ISR functions—from SATCOM relays like Skynet to missile warning platforms like SBIRS—the need for resilient coalition oversight becomes paramount.
If replicated across additional partners—and eventually automated via AI-enabled SSA platforms—such cooperative inspections could form part of routine health checks across multinational fleets operating at GEO altitudes where servicing is difficult but mission impact is high when failures occur undetected.
