Osculating_orbit

In astronomy, and in particular in astrodynamics, the osculating orbit of an object in space is the gravitational Keplerian orbit about a central body that it would have if other perturbations were not present.

An osculating orbit and the object\'s position upon it are fully described by the six standard Keplerian orbital elements, which are easy to calculate as long as one knows the object\'s position and velocity relative to the central body. However, perturbations can cause the osculating elements to evolve, sometimes very quickly. In such cases, a more complex set of proper orbital elements may better describe the most important aspects of the orbit.

The word osculate derives from a Latin word meaning "to kiss". Its use in this context derives from the fact that, at any point in time, an object\'s osculating orbit is precisely tangent to ("kissing") its actual orbit, with the tangent point being the object\'s location.

Possible perturbations that could cause an object\'s osculating orbit to change include:

• A non-spherical component to the central body (i.e., the central body is not a point mass)
• A third (or more) body whose gravity perturbs the object\'s orbit
• A non-gravitational force acting on the body. For example caused by
  • Thrust from a rocket or ion engine.
  • Atmospheric drag
  • Solar wind
  • Collisions with other objects
  • Release or ablation of a material
  • Radiation pressure

See also

• Orbital elements
• Osculation
• Osculating circle
• List of orbits

External links

• Diagram of a sequence of osculating orbits for the escape from Earth orbit by the ion-driven SMART-1 spacecraft: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35722
• A sequence of osculating orbits for the approach to the Moon by the SMART-1 spacecraft: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=36359

This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia