Read the explanation
Start with the native ISS preset, altitude four hundred eight kilometres and eccentricity zero. Then select the GEO preset, altitude thirty five thousand seven hundred eighty six kilometres, also circular. The source adds its configured Earth radius, six thousand three hundred seventy one kilometres, to altitude. Circular speed is the square root of the configured gravitational parameter divided by radius. Period scales as radius to the three halves. The higher circular orbit therefore has lower speed and a much longer period. The two exact states remain visible at labelled, separate scales. These are this educational source model calculations, not mission predictions. Return to the ISS starting altitude. Change only eccentricity from zero to zero point five. The source treats radius at closest approach as fixed, six thousand seven hundred seventy nine kilometres. Dividing by one minus eccentricity doubles the semimajor axis, and multiplying that axis by one plus eccentricity makes the farthest radius three times the closest radius. Both diagrams use twelve pixels per thousand kilometres. Gold marks the Earth focus, not the ellipse centre. The outlines are exact held geometric comparisons. This source advances its animated anomaly linearly, so the animation is not an exact Kepler timing solution. Our explanation concerns its geometric and period formulas. Keep the initial circular altitude at four hundred eight kilometres. Use the target slider to select five hundred kilometres, then compare with the native reset target, thirty five thousand seven hundred eighty six kilometres. The source averages the two circular radii to get the transfer semimajor axis. Its first burn is the difference between transfer speed and initial circular speed; its second is the difference between final circular speed and transfer arrival speed. The displayed total adds their absolute magnitudes. Transfer time is half the ellipse period. The held time bars use seventy pixels per hour. This idealized two-body calculation excludes drag, thrust duration and mission constraints. We use metric outputs; the source imperial speed conversion is not taught here.