Program NPOE
Numerical Prediction of
Orbital Events
Introduction
NPOE is a scientific simulation for Windows compatible computers
that can model important orbital events and predict the long-term evolution of
satellites in Earth orbits. Program NPOE
implements a special perturbation
solution of orbital motion using a variable step size Runge-Kutta-Fehlberg 7(8)
numerical method to numerically integrate Cowell's form of the system of
differential equations of motion.
Orbital events are predicted using Brent's method for finding the root
of nonlinear equations, and the user can control both the integration and
root-finding convergence criteria.
Program NPOE can accurately predict the time, geometric and dynamic
orbit characteristics for any physically realizable user-defined value
of the following orbit parameters:
True anomaly
Argument of latitude
Flight path angle
Geocentric declination
East longitude
Geodetic altitude
Geodetic latitude
Orbital speed
The software can also determine the time and orbital
characteristics of the following important orbital events:
Ascending node crossings
Descending node crossings
Rise and set conditions of a satellite
relative to a ground site
Visibility conditions of the Sun or Moon
relative to a satellite
Earth and lunar shadow entrance and exit
conditions
The NPOE software can model one or more of the following types of
orbit perturbations:
Earth gravity - user-defined degree and
order
Solar gravity - point mass
Lunar gravity - point mass
Atmospheric drag
Solar radiation pressure
The main program is a computational engine that propagates
orbits, predicts events and writes ASCII data files. NPOE can read and use classical orbital
elements, Two Line Element (TLE) data files or a simple position and velocity
vector data file for initial conditions.
NPOE Input Files
The NPOE main software is data-driven by a single ASCII
input file that defines all required information and user options for a
simulation. These input files can be
created or edited with any ASCII text editor.
Output Files
The user has the option of generating seven different types of
ASCII output data files. The types of
output data files that can be created with the NPOE program are as follows:
classical
orbital elements
geodetic
latitude, longitude, altitudes and atmospheric density
ECI position and velocity vectors and
magnitudes
full
precision ECI position, velocity and acceleration vectors
ground
site-to-satellite visibility conditions
Earth and moon shadow conditions
Sun and moon visibility conditions
NPOE Purchasing & Downloads
The NPOE
software can be purchased using the flexible and secure e-commerce features
offered by PayPal (www.paypal.com). PayPal accepts online payments by
credit card and a PayPal account is not required to make a purchase. Before placing an order, please read the license agreement. After placing your order, you will receive an
email within 24 hours with a password that will permit you to extract the
executable program, the DISLIN DLL and any support data files.
$99 – electronic download –
click here
to purchase this software
You can download a zipped file of the password protected executable
program and data files here.
You can download a PDF version of the user’s manual here.
The DE405 binary ephemeris file can be downloaded using the
following link:
JPL DE405 ephemeris binary data
file (~20 MB)
This binary data file is valid from 12/18/1997 to 1/11/2030. Please note that this binary file can only be
used on Windows-compatible computers.
Last updated December 21, 2009
Web site contents copyright © 1997-2009 by C. David Eagle. All rights reserved.
cdeaglejr@yahoo.com www.cdeagle.com