DSP Infrared Detection
Defense Support Program (DSP) satellites use ultra-sensitive infrared sensors capable of detecting small heat sources and reflected light on Earth's surface and in space. Originally designed to detect the infrared signature of ballistic missile launches, these sensors have proven capable of detecting much smaller and faster-moving objects, including Fast Walkers — anomalous objects entering or leaving Earth's atmosphere.
Technical Capabilities
DSP infrared sensors operate from geosynchronous orbit approximately 22,000 miles above Earth, providing continuous monitoring of large portions of the planet's surface and near-space environment. The sensors detect:
- Heat signatures: Missile plumes, explosions, and other thermal events
- Reflected sunlight: Objects passing through the satellite's field of view that reflect sunlight
- Small objects at extreme velocities: Objects moving too fast to be atmospheric, including Fast Walkers
Scan Rate and Tracking
DSP satellites scan once every 10 seconds, allowing continuous tracking of objects over extended periods. The 1976 Tehran UFO Incident detection showed 238 scans, representing approximately 39.7 minutes of continuous tracking — demonstrating the ability to maintain lock on fast-moving objects over extended durations.
Detection Range Limitations
One of the persistent challenges in Fast Walker analysis is the inability to determine precise range to targets. Both Richard P. Oszx's 1989 study and Bradley R. Townson's 2008 follow-up noted that calculating orbit or exact distance to Fast Walkers remained an "unsolvable" problem, as the objects don't follow predictable trajectories that would allow standard orbital mechanics calculations.
Sensitivity Threshold
The extreme sensitivity of DSP infrared sensors is what allows detection of Fast Walkers that ground-based systems miss. Bob Fish noted that DSP personnel in El Segundo, California required TS/SCI clearance to access facilities where this data was processed, indicating the sensitivity of the sensor capabilities and the data they collect.
Dual-Use Implications
The fact that DSP satellites designed for missile warning also detect and track anomalous objects suggests these sensors are among the most capable space-based detection systems operated by the US military. The Aerospace Corporation's documented work using DSP data to develop "hazard support systems" indicates ongoing analysis of this dual detection capability.