Free-Return Flyby Solver

CR3BP Earth–Moon rotating frame. Solves for ẋ = 0 at (1−μ + R_Moon + h, 0) — exact symmetric free-return condition. Departure angle measured from −x direction (anti-Moon, 0–90°).

Color

Earth parking orbit altitude (km)

Target lunar flyby altitude (km)

Parking orbit inclination (deg)

Solving…

Outbound

Return (toggle in controls)

Ready. Press "Solve & Plot".

Flyby altitude: —

Earth–Moon rotating frame · ● Earth (−μ,0) ● Moon (1−μ,0) ● L1–L5 ● SE-L1 ● SE-L2 (rotates with Play) · Drag to pan · Scroll to zoom

Controls

Time (days)

Speed

Steps

Show Lagrange L1–L5

Show GEO orbit

Show Sun–Earth L1/L2 (rotating)

Show spacecraft marker

Show lunar orbit at flyby altitude

Show return path (dashed)

Show Jacobi contours

Jacobi C

Axis units