Standard assumptions in astrodynamics Guide, Meaning , Facts, Information and Description
For most of the problems in astrodynamics involving two bodies and standard assumptions are usually the following:- A1: and are the only objects in the universe and thus influence of other objects is disregarded,
- A2: The orbiting body () is far smaller than central body (), i.e.:
- A3: As the result of disparities in mases between and standard gravitational parameter () includes only the mass of the central body, i.e.:
- A4: Focus of orbiting body's orbit coincides with a center of the central body,
- A5: Central body is an origin of the inertial frame of reference for the orbiting body,
- A6: Orbit of orbiting body is not perturbed in any way, so the only orbits allowed are circular, elliptic, parabolic or hyperbolic.
Examples where those assumptions do not hold
- A1: although escape velocity is described as a velocity that should allow an orbiting body to coast to infinity and arrive there with zero velocity for most cases this will not be. E.g. even if the spacecraft is launched with escape velocity with respect to Earth it will not escape to infinity (e.g. leave the Solar system) because it will eventually succumb to the gravitational influence of the Sun.
See also
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