Earth → Mars Orbit Simulation

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Timeline

🍇 grape.cool

Playback

10 sim-days / sec

Speed

Live telemetry

Sim time: day -35(T−35 days)
Mission: pre launch
Phase angle: 60.5°(opt 44°)
Transfer: 259 days
Launch day: t = 0 days from optimal window

Transfer path

Phase angle

Earth → Mars launch windows

You can only fly a cheap path to Mars when Earth and Mars line up. That trip takes about 259 days. If Mars is on the far side of the Sun, there is no straight route — you cannot fly through the Sun. Launch a year late and the same rocket misses Mars by hundreds of millions of km.

Why ~every 2 years? Earth orbits faster than Mars. The time until they sit in the right places again is the synodic period: 1 / (1/P_E − 1/P_M) ≈ 780 days (~2.14 years, about 2.1 years). Wait only 1 year and Mars is still roughly on the wrong side of its orbit — your transfer path ends empty.