Geosynchronous Satellites
Geosynchronous satellites are spacecraft that orbit Earth at an altitude of approximately 22,000 miles (35,786 kilometers) above the equator, completing one orbit in exactly 24 hours — the same rotational period as Earth. This orbital period allows the satellites to remain fixed over the same point on Earth's surface, providing continuous coverage of a specific geographic region.
Defense Support Program Use
The Defense Support Program (DSP) operates a constellation of geosynchronous satellites positioned at various longitudes around the equator. These satellites maintain constant surveillance of Earth's surface and near-space environment, detecting:
- Ballistic missile launches (primary mission)
- Nuclear detonations
- Fast Walkers and Slow Walkers (secondary/classified mission)
Advantages for Fast Walker Detection
Geosynchronous orbit provides several advantages for detecting Fast Walkers:
- Continuous coverage: Satellites remain over the same region 24/7, enabling long-duration tracking
- Wide field of view: High altitude allows monitoring of vast portions of Earth's surface and upper atmosphere
- Stable platform: Predictable orbit allows precise calibration of sensor systems
- Space background: Looking down at Earth against the backdrop of space allows detection of objects entering or leaving the atmosphere
Detection Methodology
Richard P. Oszx's 1989 paper noted that "certain ballistic missile early warning Satellite Systems located at various geostationary locations" have been recording Fast Walker data since 1972. The paper explained that Fast Walkers are detected by reflected sunlight passing through satellite sensors, indicating the satellites can pick up objects by both thermal signature and optical reflection.
Increased Detection Rates
The 1989 Oszx study stated that "the fast Walker analysis has become an increasingly important issue due to the increase in geosynchronous satellites which detect the objects while ground-based sensors cannot."
This suggests that as more geosynchronous satellites were deployed throughout the 1970s-1980s, Fast Walker detection rates increased — either because more sensors provided better coverage, or because the satellites detected objects that ground systems had been missing all along.
Ground vs. Space-Based Detection
A critical finding in Fast Walker research is that ground-based sensors cannot detect these objects. Only geosynchronous space-based infrared and optical systems have the capability to track objects entering or leaving Earth's atmosphere at the velocities and altitudes characteristic of Fast Walkers.
This detection limitation means that without DSP and similar space-based assets, the US military would have no awareness of Fast Walker activity — the phenomenon would be completely invisible to defense networks.
Current Constellation
The DSP constellation currently operates under US Space Force management, maintaining continuous geosynchronous coverage. The exact number and positions of active DSP satellites remain classified, though the constellation has been operational since the early 1970s with multiple generations of satellites deployed over five decades.