The satellite follows the closed-form two-body Kepler solution instead of numerically integrated forces. The mean anomaly M advances at a constant rate n = 2π/T set by Kepler's third law; each frame, 8 Newton–Raphson iterations solve Kepler's transcendental equation for the eccentric anomaly E, which maps directly onto the ellipse:
M = E - e·sin(E)
r(E) = a(1 - e·cosE)
v = √(GM(2/r - 1/a)) (vis-viva)
T = 2π√(a³/GM)
The Burn button is a simplified prograde impulse: it raises a and e (capped), which pushes the apoapsis outward while periapsis stays close to where it was — the same qualitative effect a real burn near periapsis has on an orbit.