Orbital perturbations

-Types of Orbital perturbations
- Factors affecting satellite visibility

1. Orbital Perturbations
Ali Sufyan
The IslamiaUniversity of Bahawalpur, Pakistan.
Email: [email protected]

2. Perturbation
Definition:a deviation of a system, moving object, or process from its
regular or normal state or path, caused by an outside influence.

3. Types of Orbital perturbations
Perturbations
Third body
Non-gravitational
forces
Non-spherical
masses
•Long term effects
Sources:
•Solar radiation
•Outgassing
•Heating
•Atmospheric drag
•Tidal friction
Precession:change
in the orientation of
the orbit (Ω,ω)
Size, shape and
orbital plane:
change in (a,e,i)
of the orbit

4. •Atmospheric Drag is a non-conservative force and will continuously take
energy away from the orbit.
•The effect of atmospheric friction is to speed up the motion of the satellite as it
spirals inward.

6. Tidal Friction Effects
The magnitude of tidal friction effects on the artificial satellites is very small.
The coupling effect of tidal friction among the massive satellites of the outer
planet, it is responsible for resonance.

7. Mutual Gravitational Attraction
Gravitational attractions of the rings will create a torque about the line of
nodes tending to turn the satellite ring into the ecliptic.
The gyroscopic effect of the torque on the spinning satellite ring will induce a
gyro precession of the orbit about the pole of the ecliptic, specifically a
regression of the nodes along the ecliptic.
The moon will cause a regression of the orbit about an axis normal to the
moon's orbit plane, which has a 5-deg inclination with respect to the ecliptic
plane with a node rate of one rotation in 18.6 yr

10. Radiation Pressure Effects
The effect of solar radiation on particles moving through interplanetary space has
been investigated for many years.
The typical radiation pressure effect on satellite orbits is the long-term sinusoidal
(yearly for geosynchronous orbits) variations in eccentricity.
The magnitude of the variation is proportional to:
the effective area
surface reflectivity
inverse of the satellite mass
For a typical communication satellite at geosynchronous altitude, the
eccentricity may vary from 0.001 to 0.004 in six months as a result of solar radiation
pressure effects.
In summary, radiation pressure induces periodic variations in all orbital elements,
even exceeding the effects of atmospheric drag. This effects on satellite lifetime.