Function altitude_from_orbital_radius 

pub fn altitude_from_orbital_radius(
    body_radius: f64,
    orbital_radius: f64,
) -> Option<f64>

Computes altitude from body radius and orbital radius.

Formula: h = r - R

Returns None when body_radius is less than or equal to zero, when orbital_radius is less than body_radius, or when the input or result is not finite.