In Astronomy, and in particular in Astrodynamics, the osculating orbit of an object in space is the gravitational Keplerian orbit about a central body which best approximates the (more complex) motion of the object at a given instant in time. Astrology: the study of the positions of the celestial objects relative to the Earth and how these positions affect happenings on the lives of cultures, nations and the natural environment. ... Astrodynamics is the study of the motion of rockets, missiles, and space vehicles, as determined from Sir Isaac Newtons laws of motion and his law of universal gravitation. ... ...

An osculating orbit and the object's position upon it are fully described by the six standard Keplerian orbital elements. The elements of an orbit are the parameters needed to specify that orbit uniquely, given a model of two ideal masses obeying the Newtonian laws of motion and the inverse-square law of gravitational attraction. ...

An orbit is usually said to be osculating to point out that its details change over a relevant time. The most common situations in which osculating orbits are specified are:

• The orbit of spacecraft, particularly those powered by ion engines which act to slowly change the orbit's parameters.
• When considering perturbations of the Keplerian orbit by bodies other than the central body.
• To contrast the slowly changing osculating orbital elements to the proper orbital elements, which remain practically constant over timescales of millions of years.

Ariane 5 lifts off with the Rosetta space probe on March 2, 2004. ... An ion engine test An ion thruster is a type of spacecraft propulsion that uses beams of ions for propulsion. ... The elements of an orbit are the parameters needed to specify that orbit uniquely, given a model of two ideal masses obeying the Newtonian laws of motion and the inverse-square law of gravitational attraction. ...

See also

• Osculation
• Osculating circle
• proper orbital elements

In differential geometry, the osculating circle of a curve at a point shares a common tangent line and a common radius of curvature with the curve at that point. ...

External link

• 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