What are the different types of satellites


© Wissenmedia / Rita Reiser
a missile that uses a missile in a circular or elliptical shape
Satellite: IRAS, orbit
Satellite: IRAS, orbit
The graphic shows the satellite IRAS in orbit around the earth.
© Jet Propulsion Laboratory
Orbit around a celestial body, usually the earth, is brought. The gravitational pull of the earth is kept in balance by centrifugal force. The circular speed required for this(Circular speed) near the earth's surface is around 7.9 km / s, the orbital time around 88 minutes. The greater the distance from the earth, the lower the orbit speed and the greater the orbital time. For example, a satellite still flies at a speed of 3.065 km / s at an altitude of 36,000 km and needs 24 hours to orbit the globe, i.e. it is always at the same point above the equator (geostationary orbit).
Different types of artificial satellites are distinguished depending on their use:
Northern Lights (satellite image)
Northern Lights (satellite image)
Northern lights over the North Pole as captured by the Swedish Viking satellite. In the north, the northern light zone extends from northern Scandinavia to Alaska at an altitude of over 100 kilometers. The cause of the northern lights are eruptions on the sun, in which protons and electrons escape. When the electrically charged particles hit the earth, their magnetic field mainly directs them into the zones 23 ° from the magnetic poles.
Geophysical and astronomical measurement satellites are used, for example, to measure the intensity of cosmic rays and the ultraviolet radiation of the sun, measure the reflectivity of the earth with regard to short-wave light rays and the radiation of long-wave heat rays, research into space rays in the Van Allen radiation belt, temperature measurements in different heights, measurement of the number and size of small meteorites, research into interplanetary magnetic fields, the gas density in space, etc. The transmission of the measurement data takes place by radio in the short or ultra short wave range. The values ​​are often stored as pulse groups on magnetic tape and sent on request when flying over a ground station. In a similar way, some functions can be controlled from the earth, such as aligning a camera with the sun or the position of the axes in space.
2. Weather satellites are used for meteorological observation of the earth's surface. They are equipped with television cameras; A wide-angle camera is used to capture large parts of the earth's surface, and a narrow-angle camera for detailed shots. The recordings are stored in magnetic tape recorders. A small programming system on board the satellite can operate the cameras. Infrared sensors also allow night recordings and temperature measurements in the atmosphere. The operating energy is supplied by solar cells and stored in accumulators.
Oceanography: Satellite Image
Satellite image of the Pacific
Shared conditions in the Pacific Ocean on July 27, 1999: An abnormally low sea level and cold water in the northeastern Pacific are contrasted by an abnormally high sea level and warm water in the northwestern part.
Wind speed: representation
Display of wind speed and direction over the Atlantic Ocean. The necessary data for this is transmitted by weather satellites.
Satellite photo of the Karakoram high mountains in Central Asia. The photo taken by Space Shuttle Discovery in April 1993 shows some of the highest peaks on earth, partially covered with snow and ice.
© NASA - Johnson Space Center, Houston
3. Communication satellites, navigation satellites: The first commercial communication satellite, "Early Bird", was launched on April 6, 1965 in Cape Kennedy; it is used to transmit long-distance calls, telex and television broadcasts. This satellite weighed 38.6 kg and had a capacity of 240 voice channels or one television channel. The current global communications satellite network uses, among other things, an advanced series of Intelsat, Astra and Eutelsat satellites. The modern type Intelsat X has, for example, 70 C-band and 36 Ku-band transponders, each of which can transmit one analog or 6–10 digital TV channels or provide around 600 ISDN data channels with a bandwidth of 32 MHz. It is 2.4 m wide, 2.9 m long, 7.5 m high and weighs 5600 kg.
4. Manned satellites are usually not referred to as satellites, but rather as Space capsules (Mercury, Gemini) or as space stations, if they serve the long-term stay of several astronauts. Manned devices with their own propulsion system are called space vehicles.
Rendezvous of Gemini 6 and Gemini 7 in earth orbit.
5. Satellites of the moon or other planets are generally called Spacecraft because they are much more complicated than earth satellites.
6. Space probes are used to explore interplanetary space and are not satellites (at most "solar satellites"); However, technically they largely correspond to the earth satellites, i.e. they are device capsules.
Model of the Galileo space probe, which was mainly used to explore Jupiter.
7. Military satellites are used for defensive or offensive military purposes. Both the US and Russia, as well as Israel and China, have it and have already launched several hundred military satellites. A distinction is made between reconnaissance (espionage), early warning, nuclear explosion and navigation satellites. In addition, there are other groups that have not yet been implemented, such as attack, laser and electronic surveillance satellites.