Please forward this error screen to 216. It is a core discipline within space mission design and control. Furthermore, the history of the fields is almost entirely shared. The specific example discussed is of a satellite orbiting a planet, but the rules of thumb could also apply to other situations, such as rules of solving differential equations pdf of small bodies around a star such as the Sun.

The square of a satellite’s orbital period is proportional to the cube of its average distance from the planet. If thrust is applied at only one point in the satellite’s orbit, it will return to that same point on each subsequent orbit, though the rest of its path will change. Thus one cannot move from one circular orbit to another with only one brief application of thrust. 180 degrees away from the firing point. The consequences of the rules of orbital mechanics are sometimes counter-intuitive. For example, if two spacecraft are in the same circular orbit and wish to dock, unless they are very close, the trailing craft cannot simply fire its engines to go faster.

This will change the shape of its orbit, causing it to gain altitude and actually slow down relative to the leading craft, missing the target. To the degree that the standard assumptions of astrodynamics do not hold, actual trajectories will vary from those calculated. Every orbit and trajectory outside atmospheres is in principle reversible, i. The velocities are reversed and the accelerations are the same, including those due to rocket bursts. Thus if a rocket burst is in the direction of the velocity, in the reversed case it is opposite to the velocity.

More accurate calculations can be made without these simplifying assumptions, but they are more complicated. The increased accuracy often does not make enough of a difference in the calculation to be worthwhile. Newton’s laws, when it is assumed that the orbiting body is subject only to the gravitational force of the central attractor. When an engine thrust or propulsive force is present, Newton’s laws still apply, but Kepler’s laws are invalidated. When the thrust stops, the resulting orbit will be different but will once again be described by Kepler’s laws.

Earth travels in its orbit. 2 with respect to object 1. All bounded orbits where the gravity of a central body dominates are elliptical in nature. A special case of this is the circular orbit, which is an ellipse of zero eccentricity.