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Introduction and Brief History of Satellites

A satellite is any object that orbits another object (which is known as it is primary). All masses that are part of the solar system, including the Earth, are satellites either of the Sun, or satellites of those objects, such as the Moon. It is not always a simple matter to determine which is the ‘satellite’ in a pair of bodies. Because all objects exert gravity, the motion of the essential object is likewise affected by the satellite. If two objects are ufficiently similar in mass, they are in general referred to as a binary system rather than a essential object and satellite. The frequent criterion for an object to be a satellite is that the center of mass of the two objects is inside the necessary object. In standard usage, the term ‘satellite’ normally refers to an artificial satellite (a man-made object that orbits the Earth or another body).

In May, 1946, the Preliminary Design of an Experimental World-Circling Spaceship stated, “A satellite vehicle with suitable instrumentation may be expected to be one of the most potent scientific tools of the Twentieth Century. The accomplishment of a satellite craft would give rise to repercussions comparable to the explosion of the atomic bomb…”

The space age begun in 1946, as scientists started out using captured German V-2 rockets to make measurements in the upper atmosphere. Before this period, scientists used balloons that went up to 30 km and radio waves to study the ionosphere. From 1946 to 1952, upper-atmosphere exploration was conducted using V-2s and Aerobee rockets. This permitted measurements of atmospheric pressure, density, and temperature up to 200 km. The U.S. had been taking into account launching orbital satellites since 1945 beneath the Bureau of Aeronautics of the United States Navy. The Air Force’s Project RAND ultimately freed the above report, but did not believe that the satellite was a potential military weapon; rather they considered it to be a tool for science, politics, and propaganda. Following pressure by the American Rocket Society, the National Science Foundation, and the International Geophysical Year, military interest picked up and in early 1955 the Air Force and Navy were working on Project Orbiter, which involved using a Jupiter C rocket to launch a little satellite called Explorer 1 on January 31, 1958.

On July 29, 1955, the White House declared that the U.S. intended to launch satellites by the spring of 1958. This became known as Project Vanguard. On July 31, the Soviets declared that they intended to launch a satellite by the fall of 1957 and on October 4, 1957 Sputnik I was launched into orbit, which triggered the Space Race amidst the two nations.

The greatest artificial satellite presently orbiting the world is the International Space Station, which may on occasion be seen with the unaided humane eye.

Types of satellites

· Astronomical satellites: These are satellites used for observation of distant planets, galaxies, and other outer space objects.

· Communications satellites: These are artificial satellites stationed in space for the intents of telecommunications using radio at microwave frequencies. Most communications satellites use geosynchronous orbits or near-geostationary orbits, though a lot of recent systems use low Earth-orbiting satellites.

· Earth observation satellites are satellites distinctively designed to detect Earth from orbit, similar to reconnaissance satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc. (See peculiarly Earth Observing System.)

· Navigation satellites are satellites which use radio time signals transmitted to enable mobile receivers on the ground to determine their precise location. The comparatively clear line of sight amid the satellites and receivers on the ground, combined with ever-improving electronics, allows satellite navigation schemes to measure emplacement to accuracies on the order of a few metres in real time.

· Reconnaissance satellites are Earth observation satellite or communications satellite deployed for military or intelligence applications. Little is known in regards to the full power of these satellites, as governments who operate them normally keep selective information pertaining to their reconnaissance satellites classified.

· Solar power satellites are proposed satellites built in high Earth orbit that use microwave power transmission to beam solar power to very huge antenna on Earth where it may be employed in place of traditionalisti power sources.

· Space stations are man-made structures that are designed for humane beings to live on in outer space. A space station is distinguished from other manned spacecraft by it is lack of major propulsion or landing facilities — instead, other vehicles are employed as transport to and from the station. Space stations are designed for medium-term living in orbit, for periods of weeks, months, or even years.

· Weather satellites are satellites that primarily are employed to monitor the weather and/or climate of the Earth.

· Miniaturized satellites are satellites of unusually low weights and little sizes. New classifications are used to categorize these satellites: minisatellite (500-200 kg), microsatellite (below 200 kg), nanosatellite (below 10 kg).

Orbit types

Many times satellites are characterized by their orbit. Although a satellite may orbit at closely any height, satellites are ordinarily categorized by their altitude:

· Low Earth Orbit (LEO: 200 – 1200km above the Earth’s surface)

· Medium Earth Orbit (ICO or MEO: 1200 – 35286 km)

· Geosynchronous Orbit (GEO: 35786 km above Earth’s surface) and Geostationary Orbit ( zero inclination geosynchronous orbit). These orbits are of queer interest for communication satellites and will be discussed in detail later.

· High Earth Orbit (HEO: above 35786 km)

The following orbits are particular orbits that are likewise applied to categorize satellites:

· Molniya orbits: Is a class of a highly elliptic orbit. A satellite placed in this orbit spends most of it is time over a indicated area of the earth, a phenomenon known as apogee dwell. Molniya orbits are named after a series of Soviet/Russian Molniya communications satellites that have been using this class of orbits since the mid 1960s.

· Heliosynchronous or sun-synchronous orbit: A heliosynchronous orbit, or more normally a sun-synchronous orbit is an orbit in which an object always passes over any given point of the Earth’s surface at the same local solar time. This is a utile characteristic for satellites that effigy the earth’s surface in visible or infrared wavelengths (e.g. weather, spy and remote sensing satellites).

· Polar orbit : A satellite in a polar orbit passes above or closely above both poles of the planet (or other celestial body) on each revolution.

· Hohmann transfer orbit: For this queer orbit type, it is more mutual to discern the satellite as a spacecraft. In astronautics and aerospace engineering, the Hohmann transfer orbit is an orbital maneuver that moves a spacecraft from one orbit to another.

· Supersynchronous orbit or drift orbit : orbit above GEO. Satellites will drift in a westerly direction.

· Subsynchronous orbit or drift orbit: orbits close to but under GEO. Used for satellites undergoing station changes in an eastern direction.

Communication Satellites

A communications satellite (sometimes abbreviated to comsat) is an artificial satellite stationed in space for the intents of telecommunications. Modern communications satellites use geosynchronous orbits, Molniya orbits or low Earth orbits.

For fixed services, communications satellites provide a technology complementary to that of fiber optic submarine communication cables. For mobile applications, such as communications to ships and planes satellite based communicationis only the viable means of communications as application of other technologies, such as cable, are impractical or impossible.

Early missions: The origin of satellite communication may be traced to an article written by Arthur C. Clarke in 1945. He suggested that a radio relay satellite in an equatorial orbit with a amount of time of 24 hours would stay stationary with respect to earth’s surface and may be used for long-range radio communication, as it will over come the limitations imposed by world curvature. Sputnik 1, The world’s original artificial (non communication) satellite, was launched on October 4, 1957. The firstborn satellite to relay communications was Project SCORE in 1958, which applied a tape recorder to store and forward voice messages. It was used to send a Christmas greeting to the world from President Eisenhower. NASA launched an Echo satellite in 1960. This 100-foot aluminized Mylar balloon served as a passive reflector for radio communications. Courier 1B, (built by Philco) likewise was launched in 1960, was the world’s original active repeater satellite. Given underneath are the details of mileposts in satellite communcation history: -

· Herman Potocnik – describes a space station in geosynchronous orbit – 1928

· Arthur C. Clarke – proposes a station in geosynchronous orbit to relay communications and broadcast television – 1945

· Project SCORE – primary communications satellite – 1958

· Echo I – firstborn passive reflector satellite – August 1960

· Courier 1B – basi active repeater satellite – October 1960

· Telstar – the original active direct relay satellite designed to transmit television and high-speed info communications. Telstar was placed in an elliptical orbit (completed once each 2 hours and 37 minutes), rotating at a 45° angle above the equator. July 1962

· Syncom – basi communications satellite in geosynchronous orbit. Syncom 2 revolved around the world once per day at uninterrupted speed, but because it still had north-south motion special instrumentation was necessitated to track it. 1963

· OSCAR-III – introductory novice radio communications satellite – March 1965

· Molniya – firstborn Soviet communicating satellite, highly elliptic orbit – October 1965

· Early Bird – INTELSAT’s introductory satellite for mercantile service – April 1965

· Orbita – basi national TV network based on satellite television – November 1967

· Anik 1 – the basi national satellite television system, Canada, – 1973

· Westar 1, the USA’s original geosynchronous communications satellite – April 1974

· Ekran – original serial Direct-To-Home TV communication satellite 1976

· Palapa A1 – basi Indonesia communications satellite – July 8 1976

· TDRSS – basi satellite designed to provide communications relay services for other spacecraft. – 1983

· Mars Global Surveyor – basi communications satellite in orbit around another planet (Mars) – 1997

· Cassini spacecraft relays to Earth images from the Huygens probe as it lands on Saturn’s moon, Titan, the longest relay to date. — January 14, 2005

Depending on the need the communicating satellites may be placed in respective types of orbits. We talk about few mutual types: -

(a) Geostationary orbits Satellites: A satellite in a geostationary orbit appears to be in a fixed position to an earth-based observer. A geostationary satellite revolves around the world at a continuous speed once per day over the equator. The geostationary orbit is utile for communications apps because ground based antennae, which ought to be directed toward the satellite, may operate efficaciously without the need for costly instrumentation to track the satellite’s motion. Especially for apps that require a huge number of ground antennae (such as direct TV distribution), the savings in ground instrumentation may more than warrant the extra cost and onboard complexity of lifting a satellite into the comparatively high geostationary orbit.

The conception of the geostationary communications satellite was initial proposed by Arthur C. Clarke, building on work by Konstantin Tsiolkovsky and on the 1929 work by Herman Potočnik (writing as Herman Noordung) Das Problem der Befahrung des Weltraums – der Raketen-motor. In October 1945 Clarke published an article titled “Extra-terrestrial Relays” in the British magazine Wireless World. The article described the basi principles behind the deployment of artificial satellites in geostationary orbits for the aim of relaying radio signals. Thus Arthur C. Clarke is oftentimes cited as being the inventor of the communications satellite.

The primary geostationary communications satellite was Anik 1, a Canadian satellite launched in 1972. The United States launched their own geostationary communication satellites afterward, with Western Union launching their Westar 1 satellite in 1974, and RCA Americom (later GE Americom, now SES Americom) launching Satcom 1 in 1975.

It was Satcom 1 that was instrumental in helping early cable TV channels such as WTBS (now TBS Superstation), HBO, CBN (now ABC Family), and The Weather Channel become successful, because these channels circulated their programming to all of the local cable TV headends using the satellite. Additionally, it was the primary satellite employed by broadcast TV networks in the United States, like ABC, NBC, and CBS, to disseminate their programming to all of their local affiliate stations. The reason that Satcom 1 was so widely employed is that it had twice the communications capacity of Westar 1 (24 transponders as opposed to Westar 1′s 12), which resulted in lower transponder usage costs.

By 2000 Hughes Space and Communications (now Boeing Satellite Systems) had built almost 40 percent of the satellites in service worldwide. Other major satellite makers include Space Systems/Loral, Lockheed Martin (owns former RCA Astro Electronics/GE Astro Space business), Northrop Grumman, Alcatel Space and EADS Astrium.

(b) Low-Earth-orbiting satellites: A low Earth orbit distinctively is a circular orbit when it comes to 150 kilometers above the earth’s surface and, correspondingly, a amount of time (time to revolve around the earth) of when it comes to 90 minutes. Because of their low altitude, these satellites are only visible from within a radius of roughly 1000 kilometers from the sub-satellite point. In addition, satellites in low world orbit modify their position relative to the ground position quickly. So even for local applications, a big number of satellites are necessitated if the mission requires uninterrupted connectivity.

Low world orbiting satellites are less highpriced to position in space than geostationary satellites and, because of their closer proximity to the ground, require lower signal strength. So there is a trade off among the number of satellites and their cost. In addition, there are necessary divergences in the onboard and ground instrumentation necessitated to support the two types of missions.

A group of satellites working in concert thence is known as a satellite constellation. Two such constellations which were intended for provision for hand kept telephony, mainly to remote areas, were the Iridium and Globalstar. The Iridium scheme has 66 satellites. Another LEO satellite constellation, with backing from Microsoft enterpriser Paul Allen, was to have as some as 720 satellites. It is also possible to offer discontinuous coverage using a low Earth orbit satellite capable of storing selective information received while passing over one part of Earth and transmitting it later while passing over another part. This will be the case with the CASCADE system of Canada’s CASSIOPE communications satellite.

(c) Molniya satellites: As mentioned, geostationary satellites are constrained to operate above the equator. As a consequence, they are not always suitable for supplying services at high latitudes: for at high latitudes a geostationary satellite may appear low on (or even below) the horizon, affecting connectivity and causing multipathing (interference caused by signals reflecting off the ground into the ground antenna). The original satellite of Molniya series was launched on April 23, 1965 and was employed for experimental transmission of TV signal from Moscow uplink station to downlink stations, located in Russian Far East, in Khabarovsk, Magadan and Vladivostok. In November of 1967 Soviet engineers formulated a distinctive system of national TV network of satellite television, called Orbita that was based on Molniya satellites.

Molniya orbits may be an likeable substitute in such cases. The Molniya orbit is highly inclined, guaranteeing good elevation over chosen positions for the duration of the northern percentage of the orbit. (Elevation is the extent of the satellite’s position above the horizon. Thus a satellite at the horizon has zero elevation and a satellite directly overhead has elevation of 90 degrees). Furthermore, the Molniya orbit is so designed that the satellite spends the great majority of it is time over the far northern latitudes, for the duration of which it is ground footprint moves only slightly. Its amount of time is one half day, so that the satellite is available for operation over the aimed region for eight hours each second revolution. In this way a constellation of three Molniya satellites (plus in-orbit spares) may provide uninterrupted coverage.

Molniya satellites are quintessentially employed for telephony and TV services over Russia. Another application is to use them for mobile radio schemes (even at lower latitudes) since cars journeying through urban areas need access to satellites at high elevation in order to secure good connectivity, e.g. in the presence of tall buildings.

Applications of Satellites

(a) Telephony: One of the major apps of a communication satellite is in provision of long distance telephone services. The connectivity is through frequency division multiple access (FDMA) or time section multiple access(TDMA) predominantly. Telephone subscribers may be connected through a network of exchanges which are in turn connected to satellite world stations which uplink the traffic to satellite for further processing.

(b) Television and Radio: There are two types of satellites applied for television and radio:

(i) Direct Broadcast Satellite (DBS): A direct broadcast satellite is a communications satellite that transmits to little DBS satellite dishes (usually 18″ to 24″ in diameter). Direct broadcast satellites in general operate in the upper portion of the Ku band. DBS engineering is applied for DTH-oriented (Direct-To-Home) satellite TV services, such as DirecTV and Dish Network in the United States, ExpressVu in Canada, and Sky Digital in the UK.

(ii) Fixed Service Satellite (FSS): Use the C band, and the lower portions of the Ku bands. They are normally used for broadcast feeds to and from television networks and local affiliate stations (such as program feeds for network and syndicated programming, live shots, and backhauls), as well as being applied for distance learning by schools & universities, business television (BTV), videoconferencing, and ordinary mercantile telecommunications. FSS satellites are also applied to disseminate national cable channels to cable TV headends. FSS satellites differ from DBS satellites in that they have a lower RF power output than the latter, requiring a much larger dish for reception (3 to 8 feet in diameter for Ku band, and 12 feet on up for C band). FSS satellite technology was also in the first place used for DTH satellite TV from the late 1970s to the early 1990s in the USA in the form of TVRO (TeleVision Receive Only) receivers and dishes (a.k.a. big-dish, or more pejoratively known as big ugly dish, systems). It was likewise used in it is Ku band form for the now-defunct Primestar satellite TV service.

(c) Mobile satellite technologies: Initially available for broadcast to stationary TV receivers, by 2004 general mobile direct broadcast apps made their aspect with that arrival of two satellite radio schemes in the United States: Sirius and XM Satellite Radio Holdings. Some manufacturers have likewise introduced particular antennas for mobile reception of DBS television. Using GPS technology as a reference, these antennas mechanically re-aim to the satellite no matter where or how the vehicle (that the antenna is mounted on) is situated. These mobile satellite antennas are standard with a lot of recreational vehicle owners. Such mobile DBS antennas are also applied by JetBlue Airways for DirecTV (supplied by LiveTV, a subsidiary of JetBlue), which passengers may view on-board on LCD screens mounted in the seats.

(d) Amateur radio: Amateur radio operators have access to the OSCAR satellites that have been designed specifically to carry novice radio traffic. Most such satellites operate as space borne repeaters, and are in general accessed by amateurs equipped with UHF or VHF radio instrumentation and highly directional antennas such as Yagis or dish antennas. Due to the limitations of ground-based novice equipment, most novice satellites are launched into reasonably low Earth orbits, and are designed to deal with only a fixed number of brief contacts at any given time. Some satellites also provide data-forwarding services using the X.25 or similar protocols.

Satellite Broadband Services: In recent years, satellite communicating engineering has been applied as a means to connect to the Internet thru broadband info connections. This is may be very utile for users to test who are located in very remote areas, and can’t access a wireline broadband or dialup connection.

Countries with satellite launch capability

This list includes regions with an independent capability to place satellites in orbit, including production of the necessary launch vehicle. Many more countries have built satellites that were launched with the support of others. The French and British capablenesses are now subsumed by the European Union under the European Space Agency.

First launch by country

Country Year of introductory launch First satellite

Russia 1957 “Sputnik 1″

United States 1958 “Explorer 1″

France 1965 “Asterix”

Japan 1970 “Osumi”

China 1970 “Dong Fang Hong I”

United Kingdom 1971 “Prospero X-3″

European Union 1979 “Ariane 1″

India 1980 “Rohini”

Israel 1988 “Ofea 1″

Iran 2005 “Sina 1″

In 1998, North Korea claimed to have launched a satellite, but this was never confirmed, and widely believed to be a cover for the test launch of the Taepodong-1 missile over Japan (See Kwangmyongsong).

Smokin Rockets Technology Television 1945 1962

Science and engineering science had a significant influence on American culture and thought in the years without delay following World War II. The new wonders of science and the threat of the Soviet Union as a powerful new enemy made science fiction a frequent genre in radio, television, and film. Mutant creatures spawned by radioactive energy and intergalactic dictators unleashing horrific weapons upon Earth were characteristic of science fiction at the time and served as warnings to the very real dangers posed by the atomic age.

This work examines science and science fiction in American culture beginning in the year World War II ended and going to 1962, the year of John Glenn’s orbital flight and the Cuban Missile Crisis. The radio work of Arch Oboler and the signification of his “Rocket from Manhattan,” which aired only one month after the dropping of the introductory atomic bomb and asked severe questions when it comes to the use of atomic energy, are examined. Other topics are the conflict among the free world and the Communist world in the context of science fiction plot lines, the dangers of science as shown in films like Godzilla, Them!, The Day the Earth Stood Still, and radio and television programs, the flying saucer phenomenon and the treatment of such stories in the media (with particular attention given to the 1956 documentary UFO), the altering and more positive depictions of scientists, television programs like Flash Gordon and Space Patrol, the shift in the remainder of world power due to the successful launching of Sputnik I by the Russians in 1957, the “end of the world” theme in science fiction, and the American journeying into space.

Smokin Rockets Technology Television 1945 1962 Image

Smokin Rockets Technology Television 1945 1962 Photo

Smokin Rockets Technology Television 1945 1962 Photo

Smokin Rockets Technology Television 1945 1962 Pic

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3 of 3 people found the following review helpful.
Links social/political changes to trends in science fiction
By Midwest Book Review
How have science and engineering science been celebrated in American film, radio and TV from 1945-1962? Smokin’ Rockets examines science and science fiction worlds in American culture from a scholarly standpoint; up to the Cuban missile crisis. Shifts in themes and making something publicly available are studied in chapters that link social and political changes to trends in science fiction.

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