This month's AE presenter: James AuBuchon
Date of presentation: 23 Sept 2019
Subject: How to Build a Space System III, Orbits
Description: Jim continued his series on how to build a space system with the third installment about orbits.
An orbit is the path taken by a celestial body under the gravitational influence of another body.
They may be open or closed. The orbital characteristics of man-made space systems may be selected to best serve the mission of the space system.
Closed orbits in a two-body system are ellipses with each body orbiting the barycenter (center of gravity) of the system.
If one of the two objects is extremely massive (in comparison to the other), the barycenter may be within the more massive body.
Such is the case in the Solar System, the Earth-moon system, and man-made satellites orbiting a planetary body.
Six parameters are required to describe an orbit. The six Newtonian parameters are equivalent to the six Keplerian parameters.
Either parameter set can be used. Orbits may be perturbed by a long list of factors, hence the need for station-keeping in man-made satellites.
Perturbations can be deliberately introduced to change the orbit for operational reasons.
Orbits of man-made satellites are selected to optimize altitude,
inclination, and synchronicity with the rotational period of the central
body, and eccentricity.
These choices represent various operational trade-offs and are selected to suit the mission of the satellite.
Some of these trade-offs are discussed in greater detail.
Satellites can be caused to orbit about Lagrange points.
