calculation of orbital mechanics

6. a regular oval shape, traced by a point moving in a plane so that the sum of its distances from two other points is constant.
7. the height of an object or point in relation to sea level or ground level.
9. the angular distance of a place north or south of the earth's equator.
12. a scientific theory where gravity is a curving or warping of space.
13. increasing in size or importance.
14. lower point in an orbit.
15. measured from or considered in relation to the centre of the earth.
16. The path of a celestial object round a star.
17. the action or process of moving or being moved.

1. the angular distance of a place east or west of the Greenwich meridian.
2. an attractive force defined on a mass.
3. a round plane figure whose boundary consists of points equidistant from a fixed point.
4. measured from or considered in relation to the centre of the sun.
5. a set of orbital maneuvers during which two spacecrafts arrive at the same orbit and approach to a very close distance.
8. decreasing in size or importance.
10. the path followed by a projectile.
11. higher point in an orbit.