Appendix G - Procedure For Determining Satellite Inclination - RESEARCH CONCEPTS RC2000C Manual

96 RC2000C Polar Tracking Antenna Controller

Appendix G - Procedure for Determining Satellite Inclination

Satellite Inclination refers to the angle of the satellite orbit with the earth's equatorial plane. Normal satellite station-
keeping maneuvers maintain the inclination near zero and the longitude to the assigned position. Satellite fuel reserves
may be extended if it is allowed to incline naturally and station-keeping is maintained only in longitude. Whereas a
geostationary satellite appears fixed in space, the apparent position of a satellite in an inclined orbit varies with time.
The pull of lunar and solar gravity combine to cause the inclination to naturally increase by 0.75 to 0.95 degrees per
year. The figure below shows increasing inclination at the rate of 0.9 degrees per year for satellites with various staring
inclinations.
The Table below lists selected satellites, their longitude and inclination as of June 1998. To use the figure with the
tabular data: 1) Locate the June 1998 inclination from the table. 2) Find that point on the left scale of the figure. 3) Move
from that point parallel to the diagonal plotted lines out to the current date. 4) The current estimated inclination is now
read from the left scale of the figure. As an example estimate the inclination of InSat 2A in March 2002. InSat 2A has a
starting inclination of 0.8444 degrees. This point is shown on the graph with an 'x'. For the year 2002 and 1/4th, the
inclination is shown by a '*', about 4.2 degrees.
Research Concepts, Inc. • 5420 Martindale Road • Shawnee, Kansas 66218-9680 • USA www.researchconcepts.com
Estimated Satellite Inclination
10
9
8
7
6
5
4
3
2
x
1
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Satellite Inclination Nomograph Table
Appendix G Determining Satellite Inclination
*
Year