INCLINED ORBIT

Inclined Satellite

A satellite is said to occupy an inclined orbit around the Earth if the orbit exhibits an angle other than zero degrees with the equatorial plane. The angle of inclination vary between 0 degree and 90 degree. This angle is called the orbit's inclination. A satellite in an inclined orbit has certain known characteristics (to a close approximation). The inclination of the satellite's orbital plane relative to the earth's equatorial plane increases at a rate of between 0.6 and 0.9 degrees per year. The rate varies from year to year.

The apparent motion of the satellite is periodic with time, the period is approximately 23 hours, 56 minutes, 4 seconds. The apparent motion of the satellite about a nominal position as viewed from the center of the earth is a figure eight pattern, as described by the following equations. Height of the figure eight (North-South): 2 * i degrees. Width of the figure eight (East-West): (i2) / 115 degrees, where it is the inclination of the satellite's orbital plane to the earth's equatorial plane in degrees.

The figure above shows three satellites in inclined orbit. One has only a small inclination, the other two much larger. The scale here is exaggerated for clarity.

ADVANTAGES

A POES satellite can hover over one polar area a large part of the time, albeit at a large distance, using a polar highly elliptical orbit with its apogee above that area. This is the principle behind a Molniya orbit used for earth-mapping, earth observation; and reconnaissance satellites, as well as some weather satellites

Geostationary satellites have revolutionized global communications, television broadcasting and weather forecasting, and have a number of important defense and intelligence applications

DISADVANTAGES

The disadvantage of the lower perigees is that they encounter more atmospheric friction, and unless the satellite has fuel to adjust its orbit, gives it a short lifetime.

The disadvantage to polar orbit is that no one spot on the Earth's surface can be sensed continuously from a satellite in a polar orbit.

The space shuttle avoids polar orbits, because flying through the aurora exposes astronauts to radiation and creates other problems.

No one spot on the Earth's surface can be sensed continuously from a satellite in a polar orbit.

One disadvantage of geostationary satellites is a result of their high altitude

Another disadvantage of geostationary satellites is the incomplete geographical coverage,

The coverage is limited to a particular area.