I am attempting to make a grid search algorithm for the CR3BP, and need to create an event for the spacecraft colliding with the secondary body (This is in a non-rotating Synodic frame). I am struggling to create an event definition for this collision. The body is located at (x,y): (1,0), but since the value component of the event function needs to be a single algebraic equation, I can’t figure out a way to log ONLY the body passing through (1,0). (If possible, this region can also be expanded to the radius of the secondary body, if one point is too small, it may be easier to expand it to a forbidden circle within the 2d orbital plane.) Need this to remove these colliding orbits from my data set, and cut down on computation, as the tight death spirals around the secondary body take a long time to compute and ultimately fail.

Tried using: Value=RadialDistance-1, but that understandably blocks out the entire orbital shell of r=1. Then tried Value=XDistance-1, but that just cut out a plane at x=1, and anytime the body crossed that line it terminated the integration.