AGEC 231 Lecture : Orbital Mechanics Higgins.pdf
26 Apr 2013
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Document Summary
Orbital mechanics: the dynamics of planetary and spacecraft motion. Circular orbits apply to spacecraft in orbits with constant altitude above planets, and are also good approximations to planets orbiting the sun. Since the spacecraft or planet is traveling in a circle at constant force outward of speed, they. This centrifugal force is balanced by gravity pulling the body inward: fgravity. Equating these two forces, which must balance if the satellite is to continue in a circular path, we obtain the velocity for a circular orbit: Two examples are low earth orbit (orbit of space shuttle or space station) with an altitude of 200 km: 7780 m/s and the orbit of the earth about the sun: Likewise, mars has an orbital velocity of vmars = 24,100 m/s. Since it is further out than the earth, the sun"s gravity does not pull as strong and so mars does not need to go as fast: elliptical orbits.
