Transfer Lab.

A single prograde burn stretches a circular orbit into an ellipse tangent to both the start and target radius. A second burn at the far side circularizes it there — skip it and the spacecraft just keeps coasting around that ellipse.

The suggested delta-v is the ideal Hohmann value. Burn more, less, early, or in the wrong direction — the actual trajectory updates immediately and honestly, even if that means missing the target orbit entirely.

Coasting continues through every optional burn point. Only you pausing, or the spacecraft hitting Earth's surface, stops the clock.

Mars must be at the right place when you arrive, not when you leave. The departure offset shifts how far along its orbit Mars sits at launch — even a perfect burn misses if the timing is off.

This model tracks the spacecraft's heliocentric path only. Arriving near Mars's orbital radius at the same time as Mars is an encounter in the model, not capture into Mars orbit — there's no Mars gravity here.

A perfect Hohmann transfer just touches Mars's orbital radius at its outbound apex without crossing it. That still counts as reaching it — the model watches for that tangent contact, not just a crossing.