The first two GSSAP spacecraft,GSSAP 1 (USA-253) andGSSAP 2 (USA-254) were launched in 2014. They were built byOrbital Sciences Corporation; their capabilities and development and construction budgets are classified. They operate in "near-geosynchronous orbit",[1][2] The first launch was scheduled for 23 July 2014 aboard aUnited Launch AllianceDelta IVlaunch vehicle.[3] Even during the testing process these satellites were pressed into early service to fulfill critical needs.[4] In August 2023 theSpace Systems Command announced the retirement of the GSSAP-2 satellite, the first of the constellation to be decommissioned, and its subsequent transfer into a graveyard orbit.
Liftoff of GSSAP 3 and 4 on 19 August 2016 atop Delta IV 375 from Cape Canaveral Air Force Station
GSSAP 3 (USA-270) and4 (USA-271) satellites were launched on 19 August 2016. On 12 September 2017, both were declared operational.[5] USA-270 approached two Chinese satellites in GEO to examine them more closely.[6] In 2023, Chinese researchers reported having observed 13 other instances where US satellites approached Chinese ones.[7]
In August 2023 theSpace Systems Command revealed that two more satellites have been ordered toNorthrop Grumman to keep up with the demand for GSSAP assets.[9] The launches of the new satellites were planned for 2024 and 2027 respectively, with the spacecraft being the first of the constellation not to be launched in pairs.[10]
The GSSAP satellites have a limit to the amount of maneuvering they can undertake, due to fuel supply limitations. In 2023Aviation Week reported that Northrop Grumman had a contract to install hydrazine refueling valves in future satellites, to enableon-orbit refueling.[14]
Chinese astronomers track GSSAP satellite movements, enabling the prediction of their observations.Chinese satellites have been observed changing orbital trajectories to observe GSSAP satellites or to make observation by GSSAP satellites more difficult.[15]
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