Excel orbit simulator update

[David Fox]

On Janez's website, at

http://orbiter.vidmar.org/orbit-simulation.php

is an updated version of my Excel program, for simulating orbits. This version adds the ability to use Mean Anomaly,
as an optional alternative to True Anomaly, for defining an orbit by its orbital elements. There is also a new column in
the main display area, showing the Mean Anomaly as it changes over the course of an orbit. Also added, are a few
more "Auxiliary Calculators," to help with defining orbits using velocities, or orbital period, and generally making
various types of orbital calculations.


This program is basically a method of exploring the characteristics of any simple orbit (characterized by Newtonian
gravitational attraction between a single orbiting body and a single, fixed central body), defined either by the initial
state vectors (position and velocity) of the orbiting body, or by its orbital elements. The orbital path is drawn
graphically (as a projection onto each of the three principal Cartesian planes), and various descriptive quantities are
displayed, as a function of time, thus enabling a prediction of the future behavior of the orbiting body, given its initial
state.

For Orbiter users, this is useful for exploring, outside of Orbiter, what may be a desirable orbit for implementing within
Orbiter, and the program produces output state vectors that can be copied and pasted into an Orbiter scenario, for
replicating that orbit (for how to do this, see the included text file: Additional notes for Orbiter users). Additionally,
there are some general purpose calculators that can be useful for determining the answers to various questions that
are often asked in the Orbiter forums (e.g. - What would be the radius of a geosynchronous orbit, or a sychronous
orbit around another planet or moon? How much velocity is needed to achieve a specified orbit?, etc.).

Other concepts, pertaining to orbits, can be explored by experienced Excel users, by graphing various quantities
against each other (e.g. - Gravitational Force, or Velocity, vs. Distance; Mean Anomaly vs. True Anomaly, etc.) and
generally playing with the program.


David Fox