In orbital mechanics, the geostationary ring is the region of space around the Earth that includes geostationary orbits and the volume of space which can be reached by uncontrolled objects which begin in geostationary orbits and are subsequently perturbed. Objects in

geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitud ...

can be perturbed by anomalies in the

gravitational field In physics, a gravitational field is a model used to explain the influences that a massive body extends into the space around itself, producing a force on another massive body. Thus, a gravitational field is used to explain gravitational phenome ...

of the Earth, by the gravitational effects of Sun and Moon, and by solar radiation pressure. A precessional motion of the orbital plane is caused by the oblatedness of the Earth (

J_2

), and the gravitational effects of Sun and Moon. This motion has a period of about 53 years. The two parameters describing the direction of the orbit plane in space, the

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired w ...

of the ascending node, and the inclination are affected by this precession. The maximum inclination reached during the 53-year cycle is about 15 degrees. Therefore, the definition of the geostationary ring foresees a declination range from -15 degrees to +15 degrees. In addition, solar radiation pressure induces an eccentricity that leads to a variation of the orbit radius by ± 75 kilometers in some cases. This leads to the definition of the geostationary ring as being a segment of space around the geostationary orbit that ranges from 75 km below GEO to 75 km above GEO and from -15 degrees to 15 degrees declination. The number of objects in the ring is increasing, and is a source of concern that the risk of collision with

space debris Space debris (also known as space junk, space pollution, space waste, space trash, or space garbage) are defunct human-made objects in space—principally in Earth orbit—which no longer serve a useful function. These include derelict spacecr ...

in this region is particularly high.

References

{{reflist Astrodynamics Earth orbits