Satellite QKD Pass — Orbital Link Budget & Secure Key Rate (2D)

This 2D companion to the 3D satellite-QKD simulator looks straight down on the orbital plane instead of orbiting a WebGL camera around it: Earth becomes a flat disk, the ground telescope a fixed point on its rim, and the satellite a dot tracing the same real circular orbit, computed from the same Keplerian period. Drag to pan and scroll to zoom the view — the physics underneath is untouched. Every second, this page independently recomputes the actual link budget from the satellite's live elevation angle: atmospheric absorption scaled by airmass, diffraction loss from the receiving aperture, the resulting quantum-bit-error-rate, and the BB84 asymptotic secure key rate from the binary-entropy formula. Toggle the eavesdropper mid-pass and watch the same security proof play out — an intercept-resend attack pushes QBER past the ~11% threshold and the key rate collapses to zero.