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Přehled hlavních drah satelitů obíhajících Zemi
Název drah Vzdálenost od povrchu Země
Nízké dráhy 160 až 2 000
Střední dráhy 2 000 až 34 780
Mezinárodní vesmírná stanice - IIS  ... 500
Sun-synchronous orbit 824
Global Positioning system - GPS ... 20 230
Geostacionární dráha  35 794
Hřbitov geostacionárních satelitů  nad 35 900


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Animované znázornění sítě satelitů GPS

GPS satelity

NASA:
- За 2014 год на Землю упало 100 тонн космического мусора, более чем 600 обломков отработавших ступеней ракет, спутников и других космических аппаратов.
- "Осадки" космического мусора в прошлом году были гораздо активнее, чем ранее.
  Это обусловлено солнечной активностью, которая подняла границу земной атмосферы, что в свою очередь спровоцировало падение космического мусора, остававшегося на низких орбитах.
- Общая масса отслуживших свой век спутников и фрагментов носителей, вращающихся на орбите 6,7 тыс. тонн.

- 750 000 000 объектов размером более одного мм.
- 4 500 000 больше одного см,
- 22,700 тыс. объектов — более десяти см
- 17 141 космических объектов,
-  1 361 это действующие космические аппараты

See also Space debris
Převzato z Internetu
Život satelitů
Satellites are carried into orbit by shuttles, where they go through a process of being launched. Shuttles flying into an orbit are inclined at 28.5 degrees to the Equator (Broad, A22). Even though a good number of satellites are carried into orbit by space shuttles, most satellites are carried by rockets. The rockets fall back into the ocean after they have launched the satellite and their fuel has run out. Sometimes they are retrieved and are used for other launches. Rockets have the capability to put satellites into orbit which are 120 miles above the Earth. Satellites which need to be put into higher orbits are first put into one orbit around the Earth and then with their motors, are pushed into higher orbits.

Even before some satellites reach space, 1 in 20 are rendered useless by either being jolted on lift-off, perish in fires of defective rocket blasts or are put into improper orbits (Canby, 282).

The life span of satellites depends largely on their size , or to be precise , it depends on how much liquid fuel they carry aboard , the liquid fuel is used to operate small rocket engines , the rocket engines are very important for the satellite (there are three types of forces acting on the satellite in space causing the satellite to deviate from its course) , the ground station on earth uses these small rockets to perform maneuvers necessary to keep the satellite in the same position in the sky (usually they perform two maneuvers every two weeks, north-south maneuver & east-west maneuver) so we can direct our antenna's here at earth(parabolic reflectors or dish) to this specific point in space & receive the broadcasted TV & radio channels & also to send telecommands from the ground station on earth to control the satellite , otherwise we need a special type of antenna's (half a billion US$ each) to track & locate the satellite , the largest satellites out there are the communication satellites (tv,radio,telephony) & they use the geostationary orbit (about 36,000 km above sea level & above the equator) & i should note that the satellite orbit around the earth depends on the speed of the satellite , once the satellite is delivered to its orbit by the rocket it was carried on, the satellite will take that orbit speed , comm. sat. also have the longest life span (it’s a round 20yrs these days) , before the satellite runs out of fuel , the ground station performs one last maneuver to send the satellite to a place called (the satellite graveyard) , it’s an orbit around the earth used to retire old useless satellites & they become junk on space , a growing problem , this is when in it come to satellites using the geostationary orbit , for satellites using lower orbits they may be put on re-entry course so they burn before they reach the earth.

Ideally (unless there is a technical failure), just before satellite end-of-life, the owner will dispose of it. Disposal generally comes in two forms: re-entry maneuver to allow it to burn up in the atmosphere or maneuver to a "graveyard" orbit (as established by international standards). The caveat would be if you are China...in which case you recklessly increase the amount of space debris by 30% by testing an anti-satellite weapon (and hope that some of that debris deorbits within the next 100 years).

By international treaty, space vehicles and satellites are generally supposed be designed to safe themselves so residual fuels and other stored energy (i.e., batteries, fuel cells, RTGs, etc.) are precluded from causing the vehicle to explode or break apart. Exploding rocket stages and satellites (caused by dead or dying controls allowing residual propellants to react) have historically been a big contributor to orbital debris problems ("space junk").

GSO satellites are supposed to be designed and operated such that right before they are about to run out of usable propellant, they raise their orbits by enough to get them out of the geostationary orbit belt and thus out of the way of the rest of the sats and any replacement vehicles. They don't usually have enough fuel to lower their orbits much and almost certainly wouldn't have enough to totally deorbit. Lowering the orbit also clutters up the transfer orbits needed for replacements. So they go higher up to die, a "graveyard orbit."

So they can hold in this "graveyard orbit" and not descend back through the Clarke Belt at any time? I think the assumption among outsiders is that all orbits decay and eventually, everything will re-enter the Earth's atmosphere.

From a bit of internet research, it supposedly takes a few hundred years to decay from graveyard orbit to geostationary, and longer still to reenter the atmosphere. Sounds like we'll have a signficant problem on our hands in couple hundred years as the dead satellites begin to interfere with the active ones. Hope our kids figure out how to deal with it.

Satellites in orbit might be killed on purpose while others need to be rescued to get repaired. Since satellites can cause interference with other orbits or are just not needed anymore, countries such as the United States and the Soviet Union have taken actions to kill these satellites. The United States uses a F-15 fighter which fires a two stage missile at it's target, the satellite. Using telescopes as it's eyes, the 50 pound warhead adjusts it's flight path so that it might intercept the path of the satellite. The Soviet Union uses a heavy satellite, the hunter-killer, which is boosted to the same orbital path as the target satellite. The hunter-killer, when in the same orbit as the target satellite , closes in and explodes destroying the target satellite (Canby, 333). Satellites in need of repair and rescue are assisted by shuttles while the satellites are in low orbits. Many satellites get repaired while other satellites in the wrong orbit get returned to Earth to be launched into the correct orbit or to be repaired.