# Orbital Predictions

Utilising information and telemetry data transmitted from satellites, in conjunction with mathematical models, it is possible to make reasonable estimates as to where a satellite may be positioned and its movement. 

This is used for a wide range of applications such as satellite-based image mapping, navigation systems, and satellite tracking systems.

## Visual Passes

A visual pass occurs when a satellite becomes visible to an observer on the ground as it traverses the sky. This happens when the satellite reflects sunlight while it passes overhead, usually during dawn or dusk when the sky is dark enough for the satellite to be visible, yet it is still illuminated by the Sun.

## Radio Passes

A radio pass refers to the specific time frame when a satellite is within the range of a ground station’s radio antenna, facilitating radio communication between the two entities. During this period, the satellite remains above the local horizon and is directly visible to the ground station, allowing for the transmission and reception of radio signals.<br>

## Simplified General Perturbations 4 (SGP4)

SGP4, a mathematical algorithm, calculates the state of an Earth-tracking satellite using its Time and Epoch Leap Second (TLE) sets. It accounts for various perturbations, such as gravitational fields from nearby celestial bodies, atmospheric drag, and the Earth’s oblateness, to predict the orbits of artificial satellites launched into space.

#### References

<https://systemweakness.com/satellite-osint-space-based-intelligence-in-cybersecurity-e87f9dca4d81>


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