This calculator estimates the footprint radius of a satellite — the maximum range it can "see" the Earth, assuming a line-of-sight view to the horizon.

Based on satellite altitude \( h \), and assuming a spherical Earth with radius \( R = 6371 \, \text{km} \), the footprint radius is calculated as: \[ d = \sqrt{(R + h)^2 - R^2} \] Where:

• d: maximum ground coverage radius (km)
• h: satellite altitude above Earth's surface (km)

This is useful for estimating coverage of satellites in Low Earth Orbit (LEO), Medium Earth Orbit (MEO), or Geostationary Earth Orbit (GEO).