Abstract
Quasi Zenith Satellite System is a satellite navigation system to serve over the whole area of the East Asia and the Oceania region.
The ground trace of the satellite changes gradually due to the orbit perturbation caused by the earth gravity, moon, sun and solar radiation pressure.
To study maintenance of the ground trace it was needed to know the characteristics of the orbit.
In this paper we described the characteristics of the longitude of ascending node (LAN), the eccentricity (e) and the other parameters.
The earth Non-Zonal term induces the harmful perturbation onto the semi major axis (a), which directly relates the longitude of ascending node (LAN) and the average longitude of the ground trace.
The fluctuation of the eccentricity (e) is depend on right ascension of ascending node, and is not negligible.
The orbit which has the right ascension of ascending node = 210deg is the most stable orbit.
And we also suggest that it is important to control two parameters, the eccentricity and the semi major axis to maintain the ground trace.
The maintenance interval should be from 6 months to 12 months.
