This game is quite amazing. At first, I found it so frustrating, then figured out much of it...
I believe if you added one element: when you click Orbit, and you move your mouse, show both the Orbit and the line to Approach the Orbit and the intersection. The fact that the Approach doesn't always get into the Orbit at the closest point is...challenging. ;-)
Adding Orbit direction would also be intriguing...
Beautifully done! And it's a great introduction to the complexities of Space Travel!
I would love to talk to you about the math, of intersecting lines and circles, and calculations of intersecting tangents.