U.S. Co-Orbital Anti-satellite Testing Fact Sheet
This fact sheet reviews U.S. historical experimentation and existing technologies relevant to co-orbital ASAT capabilities, despite the absence of an acknowledged operational program. It outlines past tests and current technical capacity that could, if reoriented, support future co-orbital ASAT development.
Key topics include:
- Project SAINT (1960–1962): An early USAF “satellite inspector” project that aimed to develop close-approach vehicles—potentially with onboard kill mechanisms—but was cancelled before launch due to budget and political constraints.
- Delta 180 Experiment (1986): The only confirmed U.S. co-orbital intercept test, part of the Strategic Defense Initiative (SDI). A modified Delta 2 launch vehicle successfully intercepted a target in low Earth orbit at 3 km/s. The test created debris, though all fragments reentered within seven months.
- RPO Missions and Tech Tests:
- Prowler (1990): Conducted undetected RPO in GEO.
- XSS-11 (2006): Demonstrated close approach and inspection in LEO.
- GSSAP satellites (active): Perform close inspections and SSA in GEO.
- Golden Dome Missile Defense Initiative (2025): Launched by executive order from President Trump, the program envisions a space-based interceptor layer. Although intended for missile defense, such systems could also enable a latent co-orbital ASAT capability, depending on design and policy choices.
The fact sheet emphasizes that while the U.S. does not currently deploy or acknowledge co-orbital ASAT systems, its technical readiness—from SSA infrastructure to proximity operations—would allow it to develop and field such systems relatively quickly if desired.
See page 2 for technical details of the Delta 180 test and the planned architecture of Golden Dome.
Timeline of known/suspected co-orbital ASAT-related activity included at the bottom of page 2
