Today in an orbit of Earth is tens of thousands of various satellites. They carry out the most various tasks: communication satellites, scientific stations, navigation, meteorological, the military reporting a body and radio signals.
Satellites — need for everyday life of the person
The sizes of artificial satellites are quite various: from one hundred meters to several centimeters. Each satellite has the problem and the trajectory of the movement or an orbit. The movement of satellites is supported by the speed set at the beginning, an attraction of the planet and happens by inertia, like the Moon or other natural bodies of the Solar system.
The movement happens on elliptic orbits in the imagined plane passing through the center of Earth. Geostationary satellites move synchronously with rotation of the planet round its pivot-center and are constantly over the same point of a surface at the height of 35 thousand km. These are satellites mostly transmitting TV signal and also GPRS.
The satellites having an elliptic orbit are at various distance to Earth. The most distant point is called apogee, the closest — a perigee. And at the same time have various speed: closer to the planet — linear speed is higher, is farther from the planet — speed more slowly. Than the orbit inclination concerning the equator plane is more, especially the satellite is noticeable in northern latitudes. And than the orbit is higher, in the bigger territory of Earth it is visible to those. There are types of orbits: polar, equatorial, solar-synchronous. The equatorial orbit passes parallel to the equator, polar — perpendicularly. In a sun-synchronous orbit the satellite is in the constant place concerning the sun over the lit or dark side of the planet. Such satellites are used generally for photographing of a surface.
Dangerous "space debris"
Delivery of satellites to an orbit is carried out by multistage rockets which use an intermediate orbit for dumping of the fulfilled parts. Thus all parts of buildings of rockets remain in Earth orbit. For all the time of stay in space of technical means on their near-earth space there are many hundreds of thousands now. Among them there are also 32 thrown failed nuclear reactors. Also a set of various fasteners and tools make a way on an own orbit. And all this moves with a huge speed. And even a harmless bolt, flying with a speed quicker than a bullet, can cause irreparable damage to the acting equipment and astronauts. Unfortunately today the near-earth space is oversaturated by "space debris". The earth looks like the sphere shrouded in a cloud, sparkling in beams of the Sun now. All this speaks about human ingratitude to those who presented at the time invaluable knowledge thanks to which the person uses the civilization benefits now.