(Polar sun synchronous orbit)

A Tracking, Telemetry and Control (TT amp C) station is used to support polar satellites during the launch phase and when in service in their nominal orbits.

It utilizes LEO store and forward satellites in polar orbit.

The current network includes six satellites in geostationary orbit and three in polar orbit.

The CRTS has also had discussions and taken steps to make a launch in polar or quasi polar orbit.

A distinction should be made between the near equatorial or low inclination orbits, for which the visibility zone will be limited to the topical zone, and the polar and quasi polar (Sun synchronous) orbits that allow accessibility to any point on Earth, either for communication (e.g. store and forward) or for remote sensing of Earth.

It consists of two pairs of satellites, one known as quot eccentric quot , inserted in a high apogee orbit (200,000 km) and the other known as quot auroral quot , inserted in a lower apogee orbit (20,000 km).

Complementing the geostationary satellites are two POES.

There are three general classes of orbit that may be suitable for small satellites the geostationary orbit (GSO), the highly elliptical orbit (HEO) and the low Earth orbit (LEO).

Basic orbital parameters Geostationary orbit

TUBS LEO MEO

Polar Orbit Earth Observation Mission (ENVISAT 1 and METOP 1)

9. On orbit collision avoidance (for LEO)

from a low intensity collision in GEO graveyard orbit (bottom)

2. The spacing between GEO and the graveyard orbit

A Tracking, Telemetry and Control (TT amp C) station is used to support polar satellites during the launch phase and when in service in their nominal orbits.

Polar orbiting satellites pass near the North and South Poles 14 times a day.

For that purpose, mainly three modes of operations were developed first a tracking mode of operation to measure selected objects in low Earth orbit, in geosynchronous orbit and in geostationary transfer orbit.

GEO satellite deorbit after EOL and

The following ESA geostationary satellites have been re orbited OTS 2 (orbiting 318 km above GSO), GEOS 2 (260 km), Meteosat 2 (334 km), ECS 2 (335 km) and Olympus 1 (due to a failure, this satellite has been left at orbit 213 km below GSO).

Whereas the collision risk between an orbiting object and a meteoroid is essentially independent of altitude, the probability of collision between orbital objects is strongly related to altitude, in general being an order of magnitude higher in LEO than in GEO.

Basic orbital parameters Geostationary orbit

The geostationary orbit

(Geostationary orbit)

GTO upper stage deorbit

38. The following ESA geostationary satellites have been reorbited so far OTS 2 (orbiting at 318 kilometres above GSO), GEOS 2 (260 kilometres), Meteosat 2 (334 kilometres), ECS 2 (335 kilometres) and Olympus 1 (because of a failure, this satellite has been left in an orbit 213 kilometres below GSO).

It has a fairly substantial number of asteroids between the orbit of the Earth out through to the orbit of Jupiter.

In the United States, four groups of such satellites are deployed, namely, communications intelligence (COMINT) in the geostationary orbit (GSO) and signals or electronic intelligence (ELINT) satellites in the GSO and in high elliptical Earth (HEO) and low Earth (LEO) orbits.

B. Geostationary orbit 32 39 6

(h) Upper stages used to transfer geostationary spacecraft from geostationary transfer orbit to geostationary orbit should, on completion of the mission, be inserted into a disposal orbit that has a perigee at least 300 km above the geostationary orbit

40. Most of the United States SIGINT ELINT satellites are placed in the GSO and do not get a good coverage of the northern and the southernmost parts of the Earth.

(c) Disposition of the objects on geostationary transfer orbit so as not to pose a risk to the geostationary orbit

3. Little LEO

The upper stages or components of launch vehicles left in GTO may be either soon removed from orbit or, if removal is not possible, manoeuvred to prevent interference with systems in GEO.

(e) Deorbiting at end of LEO and GTO mission this includes both lowering the orbit to reduce the satellite lifetime (e.g. to less than 25 years) and immediate re entry.

For that, mainly three modes of operation were developed a tracking mode of operation to measure selected objects in low Earth orbits (LEO), in geosynchronous orbits (GSO), and in geostationary transfer orbits (GTO).

The Celestri LEO system was designed to enable frequency sharing of the Ka band spectrum with GSO and other LEO systems by using satellite diversity.

The majority of the passages of polar orbiting satellites are inside the coverage zone of the Esrange satellite ground stations.

The current operational constellation includes at least three polar orbiting and six geostationary satellites.

GEO satellites were also designed and operated to conduct reorbit manoeuvre at the end of the mission to preserve the GEO environment. F. Conclusion

The upper stages or components of launch vehicles left in GTO may be manoeuvred to prevent interference with systems in GEO.

The Subcommittee agreed that the words disposal orbit should be used in lieu of the words graveyard orbit .

The mission INTERBALL consists of two pairs of satellites, one in a fairly low orbit (Auroral Probe, apogee 20,000 km) and the other with an apogee of 200,000 km (Tail Probe). These two very different orbits were chosen in order to cover the auroral and the tail region of the Earth apos s magnetosphere, respectively.

The minimum diameter of observable objects was about 10 centimetres for LEO and 1 metre for geostationary satellite orbit (GSO).

The model is applicable to altitudes from LEO to GEO, providing environment estimates in the short term.