Orbital mechanics or astrodynamics is the study of
the motion of
rockets
and other
spacecraft. The motion of these objects is usually calculated
from
Newton's laws of motion and
Newton's law of universal gravitation, collectively known as
classical mechanics.
Celestial mechanics focuses more broadly on the orbital motions of
artificial and natural astronomical bodies such as
planets,
moons, and
comets.
Orbital mechanics is a subfield[citation
needed] which focuses on spacecraft
trajectories, including
orbital maneuvers, orbit plane changes, and interplanetary transfers,
and is used by mission planners to predict the results of
propulsion.
General relativity provides more exact equations for calculating orbits,
sometimes necessary for greater accuracy or high-gravity situations (such as
orbits close to the Sun).
