1. Define a coordinate system such that the vertex of the parabola is at V(0, 0) and the parabola is opening up.

2. Draw a sketch. (see attachment)

3. Let r denote the radius of the moon. Then the equation of the parabola in question is with the focus at F(0, 143+r) . That means

4. Since and the satellite has the coordinates

5. Plug in the value of p and the coordinates of S into the equation of the parabola:

6. After moving some stuff around (a lot of stuff btw) you'll get a quadratic equation in r:

which yields 2 solutions. The negative solution isn't very plausible here. so it is