SATELLITES
Orbits
Satellite Timeline
CIRCLING THE EARTH,High above our heads,Satellites are messengers and observers in the Sky.they relay telephone calls,Watch and Weather,guide ships and aircraft,and carry out tasks that are Impossible on the ground.they travel 10 to 30 times faster than airliner.A satellite's speed prevent it from falling to the Earth and throws it outward.The inward pull of gravity balances this outward force and traps the satellite in an endless path around the Earth.
Anatomy of Satellites
A satellite is a moon, planet or machine that orbits a planet or star. For example, Earth is asatellite because it orbits the sun. Likewise, the moon is a satellite because it orbits Earth. Usually, the word "satellite" refers to a machine that is launched into space and moves around Earth or another body in space.
Satellites have 6 basic parts:
1. Satellite housing- The shape of the housing (outside container) of the satellite depends upon the
system employed to keep the satellite within the orbit at a stabalized altitude. If the satellite has a
three-axis stabilization system, its housing will be rectangular with solar panels protruding from two
opposite sides. If the satellite has a spin stabilization system, the housing will be cylindrical. The
solar cells will be mounted on the surface of the cylinder. The antenna will be connected on the body
by a rotating bearing to keep it pointed in a fixed direction.
2. Power System- Satellites must have a continuous source of electrical power. The two most common
power sources are high performance batteries and solar cells. Solar cells are lightweight, resilient, and
their efficiencies have been improving over the years. There is one large problem with solar panels.
Twice a year geosynchronous orbit will go into a series of eclipses where the sun is screened by the earth. To solve this problem, batteries are used as supplemental on-board energy sources.
3. Antenna System- has two jobs:
a. Receive and transmit telecommunications signals
b. Provide tracking, telemetry, and command functions which maintain the satellite's operation in orbit.4. Command and Control System- The "brain" of the satellite. It monitors the satellite to ensure that all vital operating parameters are working. It receives the data from the earth station, interprets the commands, and relays the processed information to earth.
5. Station keeping- To ensure that the satellite stays in its orbit, this system employs the controlled
ejection of hydrazine gas from thruster nozzles. The useful life of a satellite is over when its several
hundred pounds supply of hydrazine gas is depleted. (Average life span=10 years)
6. Transponders- Electronic mechanisms that amplify the frequency of an uplink signal for retransmission to earth.
Orbits
There are many different satellite orbits that can be used. The ones that receive the most attention are the geostationary orbit used as they are stationary above a particular point on the Earth.The orbit that is chosen for a satellite depends upon its application. Those used for direct broadcast television for example use a Geostationary orbit. Many communications satellites similarly use a geostationary orbit. Other satellite systems such as those used for satellite phones may use Low Earth orbiting systems. Similarly satellite systems used for navigation like Navstar or Global Positioning (GPS) system occupy a relatively low Earth orbit. There are also many other types of satellite from weather satellites to research satellites and many others. Each will have its own type of orbit depending upon its application.
The actual satellite orbit that is chosen will depend on factors including its function, and the area it is to serve. In some instances the satellite orbit may be as low as 100 miles (160 km) for a Low Earth Orbit LEO, whereas others may be over 22 000 miles (36000 km) high as in the case of a GEostationary Orbit GEO. The satellite may even have an elliptical rather than a circular orbit.
Satellite Timeline
Throughout history satellites have moved from having no special capabilities to being able to explore other worlds. This has led to new technologies, to improve and better our society because of the discoveries, The outline of all the things that have occurred are listed below. Beginning from the first launched and going all the way to the more modern ones.
1950' S
On October 4, 1957 Sputnik 1 was launched, it was the first man made object to orbit the earth. It was named Sputnik Zemli or traveling companion of the world by the Soviet Union. Soon after on January 31, 1958 the US launched its first satellite called Explorer 1. Over the next few years many improvements were made in satellite technology.
October 4,1957 Sputnik 1 launched- USSR
November 3,1957 Sputnik 2 launched- USSR
January 31, 1958 Explorer 1 launched- USA
March 5,1958 Explorer 2 launched- USA
March 17,1958 Vanguard 1 launched
May 15,1958 Sputnik 3 launched- USSR
October 11,1958 Pioneer 1 launched- USA
January 2,1959 Luna 1 launched- USA
March 3,1959 Pioneer 4 launched- USA
September 12,1959 Luna 2 launched- USSR
October 4,1959 Luna 3 launched- USSR
1960' S
During the 1960's improvements in satellites continued. The first men were launched for both the US in Mercury Freedom 7 and for the USSR in Vostrok 1. Great developments continued in space such as exploring other planets and sending signals across the ocean.
April 1,1960 Trios 1 weather satellite launched- US
August 18,1960 Discovery XIV spy satellite launched- US
April 1,1961 Vostrok 1 carrying first man in space- USSR
May 5,1961 Mercury Freedom 7 first US man in space- US
August 6,1961 Vostrok 2 first 5 day flight- USSR
July 10,1962 Telstar 1 completed first transatlantic telecast- US
December 16, 1962 Mariner 2 flies past Venus into solar orbit- US
July 31,1964 Ranger 7 takes first close range photos of moon- US
March 24,1965 Ranger 9 transmits first live moon photos- US
July 14,1965 Mariner 4 returns first close range images of Mars- US
November 16,1965 Venus 3 first craft to impact Venus- USSR
February 3,1966 Luna 9 first to soft land on the moon- USSR
March, 1966 Surveyor 1 first US soft land on moon- US
August 14, 1966 Lunar Orbiter 1 returns first pictures of earth- US
September 15, 1968 Zoned 5 orbits moon and returns- USSR
July 31, 1969 Mariner 6 returns images of Martian surface equatorial region
August 5, 1969 Mariner 7 returns images of Martian surface southern hemisphere
1970' S
The study of other planets through the use of satellites continued and they were used more often to map the other planets in our solar system. The satellites were used mainly to find out the conditions on the other planets and to try to find life on other planets mainly, Venus and Mars.
September 12,1970 Luna 16 returns lunar oil samples- USSR
November 17,1970 Luna 17 first automatic robot on moon travels 11 days- USSR
December 15,1970 Venera 7 first to soft land on Venus- USSR
May 30, 1971 Mariner 9 first mars survey from orbit- US
November 13, 1971 Mariner 9 maps 100% of Martian surface
March 2, 1972 Pioneer 10 designed to familiarize alien life with humans, returns close ups of Jupiter 1973- US
April 5, 1973 Pioneer 11 discovers new rings around Saturn- US
November 3, 1973 Mariner 10 returns photos of Venus and Mercury- US
May 17, 1974 SMS-1 Synchronous Meteorological Satellite- US
October, 1975 Venera 9 and 10 return photos of Venus and mercury surface- USSR
July 20,1976 Viking 1 pictures of Martian surface- US
September 3, 1976 Viking 2 lands on Mars plain of Utopia discovers water frost
August- September 1977 Voyagers 1 and 2 leave earth for Jupiter and Saturn
1980'S
Throughout the 1980's the exploration of our galaxy continued and stretched into the belief of their being others planets like earth. Numerous photos continued being returned and the technology pushed satellites into new dimensions.
June 19, 1981 third Ariane rocket launched by the European Space Agency
December 20, 1981 fourth arien rocket launched by ESA
October 10, 1983 Venera 15 returns first photos of Venus polar region- USSR
January- November, 1983 Inferred Astronomical satellite discovers new comets, asteroids, galaxies and a dusting around the star vega that may be new planets
December, 1984 Vega 1 and 2 launched, drops probes into Venus's atmosphere- Soviet/ international
January 8, 1985 Skigate launched by Japan's institute space and aeronautical science first to rendezvous with Haley's comet
July 2, 1985 Giotto launched by ESA from an Ariane rocket, encounters both Haley's comet and comet P/Grigs-Skjellerup
July 12, 1989 Phobous 2 orbits Mars studying atmosphere and magnetic field- Soviet/ international
October 18, 1989 Galileo launched from shuttle Atlantis took pictures of Venus and asteroid Ida then continues to Jupiter- US
1990'S
So far through the 1990's satellites continue being improved. Yet space ships seem to be improving faster and taking over what these satellites have accomplished so far.
August, 1990 Magellan arrives at Venus and takes radar images of the surface- US
February 8, 1992 Ulysses flies around Jupiter and heads towards the sun
January 24, 1994 Clemintine performs lunar mapping mission- US
October 12, 1994 NASA launches first in a series of discovery series of spacecraft the Near-Earth Asteroid Rendezvous [NEAR] space craft aboard a Delta 11-7925-8 rocket
Over the last 40 years satellites have come a long way. The changes in technology have brought new ideas on what can be accomplished in future space exploration. The future still looks great for satellite function and exploration.
Konstanin Tsiolkovskill
Konstantin Eduardovich Tsiolkovsky (1857-1935)was a Russian and Soviet rocket scientist and pioneer of the astronautic theory, of Russianand Polish descent. Along with his followers, the German Hermann Oberth and the American Robert H. Goddard, he is considered to be one of the founding fathers of rocketry and astronautics. His works later inspired leading Soviet rocket engineers such as Sergei Korolev and Valentin Glushko and contributed to the success of the soviet space program.
No comments:
Post a Comment