Spacecraft do not fly straight to a planet. A Hohmann transfer uses two impulses: enter an elliptical transfer orbit, then circularize at the target. Delta-v is the fuel currency of spaceflight. The vis-viva equation v² = μ(2/r − 1/a) gives orbital speed at every point. Plane changes are expensive because the velocity vector must rotate; the simulator combines circularization and plane change vectorially.
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