Arthur C. Clarke. the British engineer turned author, is credited with envisioning the key elements of satel­ lite communications long before the technical skill or political will to implement his ideas existed. In 1945, he published a plan to put electronic relay stations-a radio receiver and retransmitter-into space at 23,000 miles above the Earth's equator. At this altitude, the satellite must complete a full rotation around the Earth every 24 hours in order to sustain orbit (countering the pull of the Earth's gravity). Given the rotation of the Earth itself, that keeps the satellite in the same relative position (or "parking space"). This "geosynchronous orbit" is where communications satellites sit today, providing telephone and data communications but mostly relaying television signals (television is the largest user of satellite bandwidth).

An “uplink" transmitter on Earth, using a "dish" an­tenna pointed toward the satellite, sends a signal to one of the satellite's "transponders." The transponder am­plifies that signal and shifts it to another frequency (so as not to interfere with the incoming signal) to be transmitted back to Earth. A "downlink" antenna and receiver on Earth then captures that signal and sends it on its way. The essential advantage of the satellite is that the uplink and downlink may be 8,000 miles apart. In practice, satellite communications is more efficient over a shorter distances than that, but the advantages over terrestrial transmissions cable, fiber optics, and microwave-are profound, particularly across oceans. As with direct broadcast satellites (DBSs), satellites can transmit to an unlimited number of ground re­ceivers simultaneously, and costs do not increase with distance or number of receivers.

Each satellite has a distinct "footprint," or coverage area, that is meticulously shaped and plotted. In 1971, the first communications satellites carrying "spot beam" antennas were launched. A spot beam antenna can be steered to focus the satellite's reception and transmission capabilities on a small portion of the Earth, instead of the 40 percent of the Earth's surface a wider antenna beam could cover. Spot coverage is cru­ cial in international broadcasting when neighboring countries may object to signal "spillover" into their territory. South Korea, for example, has demanded limitations on satellite broadcasts into its territory from Japanese companies.

Communications satellites since the 1960s have re­ceived uplink signals in a range of frequencies (or "bandwidth") near 6 GHz (gigahertz, or a billion cy­cles per second) and downlinked signals near 4 GHz. This range of frequencies is known as "C-band ." Each range of frequencies is subdivided into specific chan­ nels, which, in the case of C-band, are each from 36 to 72 MHz wide. In the past, a single analog television transmission would occupy enough bandwidth to fully utilize a single 36-Mhz channel, though hundreds or thousands of voice or data signals requiring far less bandwidth would fit on the same channel. More re­ cently, the use of digital compressed  transmissions and higher frequencies has allowed far more televi­ sion channels per satellite and cut the cost of satellite use.

For decades, many developed and developing coun­ tries have used satellite-delivered television to provide useful in formation to portions of their populations out of reach of terrestrial broadcasting. In 1975, an experi­ mental satellite communications project called SITE (Satellite Instructional Television Experiment) was used to bring informational television programs to ru­ ral India. The project led to Indian development of its own satellite network. China has also embarked on a ambitious program of satellite use for development, claiming substantial success in rural education. Many countries, including India, China, Japan, Russia, and Mexico; the European and Asian satellite consortiums; and at least two private companies now launch satel­ lites. During the 1990s, satellite communications shifted from mostly public hands-dominated by the multilateral Intelsat organization-to mostly private hands, with governments auctioning off or giving away their valuable satellite orbital allocations to pri­ vate companies.

In the  late  1970s,  with  the satellite distribution of Home Box Office (intended only for cable television companies to receive and relay movies to paying cus­tomers), "television receive only" (TYRO) dishes be­ came popular for people out of reach of cable television and anyone wishing to avoid the cost of a cable subscription. The large dishes of that era still lit­ter the backyards of rural America. Later, DBS to small home dishes became possible through the use of higher frequencies. Since 1988, with the launch of British Sky Broadcasting. DBS has been heavily used in Europe and, around the same time, eastern Asia; it continues to gain popularity in the United States but still has less than one-quarter of the subscribers of cable television .

In the 1980s, satellites using bandwidths of 11 to 12 GHz (uplink) and 14 GHz (downlink) came into use. This "Ku-band" does not require as much power to be transmitted clearly, thereby permitting the use of small (and less expensive) Earth stations. With the in­troduction of the Ku-band, television entered the era of live news-satellite news gathering (SNG)-as Ku-band satellites made it easy to uplink television signals with a portable dish from the scene of a break­ing news story. Overuse of the C and Ku bandwidths and the desire for even greater signal strength is lead­ ing to new satellites that use other areas of the radio spectrum. Television news has also made some use of another satellite technology. remote sensing, using pictures taken by satellites to illustrate or verify news stories. In the 2003 Iraq war. television networks of­ ten combined satellite imagery with elaborate ani­ mated graphics to illustrate the war, but the U.S. government purchased all the best commercially available satellite imagery to prevent the media from using it.

Encryption, or scrambling. of satellite television signals has become common to ensure that only cus­ tomers who have bought or rented a decoder can re­ ceive transmissions. Even intercompany television feeds via satellite (traditionally known as "back­ hauls"), such as daily feeds to broadcasters from tele­ vision news agencies, are encrypted to prevent unauthorized use. With increasing frequency. interna­ tional television companies now shift production work from one part of the world to another using com­ pressed video files transmitted via private satellite links. A news agency's Chinese bureau, for instance, might transmit masses of unedited video of a major story to London to be edited and sent out to global broadcasters, shifting the burden-and, potentially. control of the story-from local areas of expertise to a few global production centers.

Like other communications technologies, the satel­lite industry has also embraced digitalization and sig­nal compression as a means of maximizing the use of limited bandwidth, and DBS and intra-industry ser­vices are expanding rapidly as a result. By converting analog signals to digital signals, less bandwidth is re­quired, and digital signals can be broken into smaller pieces for transmission through bits of available band­ width and reassembled at the point of reception. Com­pression eliminates otherwise redundant portions of a television transmission, allowing for a signal to be sent using far less bandwidth and for the transmission of video as computer files moving from one computer or database anywhere in the world to another. Compres­sion technology now permits hundreds of television channels on a single satellite. Telephony and television use roughly equivalent portions of available satellite capacity. but the demand for DBS has led to a number of satellites dedicated to TV transmission. Currently. well over 200 commercial geostationary communica­ tions satellites are in use, but with constant new launches and removals from orbit of old satellites. the number changes frequently.

STAR-TV. controlled by media mogul Rupert Mur­ doch. transmits television programming over much of Asia and has forced governments worldwide to re­ evaluate their stance on issues of national sovereignty and control of incoming in formation . STAR reaches over 50 countries and potentially half the world's pop­ ulation-far more than any other satellite television service (though it is technically not DBS. still requir­ ing larger dishes). A slew of contentious political and cultural issues have resulted. Murdoch dropped the British Broadcasting Corporation (BBC) World Ser­ vice Television from his STAR-TV program lineup as a concession to the Chinese government. Other gov­ernments have complained about the unrestricted im­portation of news presented from an Anglo-American viewpoint. though their concerns about political conse­quences are often couched in terms of protecting local culture. Reports of disruptions to local cultures stem­ming from international satellite broadcasting are widespread. Also during the 1990s. Africa, the one continent long neglected by the satellite television in­dustry. finally saw widespread availability of satellite television services, dominated by the South African company M-Net.

By 2004, over 20 million U.S. homes subscribed to one of two DBS services: DirectTV or EchoStar (most recently using the brand name "Dish Network"). In 1995, EchoStar launched its own satellite and by 2004 had eight satellites in orbit over the United States, broadcasting digital television, audio. and data chan­nels. DirectTV is a division of Hughes Electronics, a manufacturer and (through PanAmSal) operator of satellites. After a long regulatory battle, at the end of 2003 Rupert Murdoch's News Corporation was given permission to buy DirectTV and take a controlling in­terest in Hughes-positioning them to be the leading satellite TV provider on five continents (Australia, Asia, Europe, South America, and North America). A friendly Federal Communications Commission al­lowed Murdoch to avoid the long-standing require­ment that DBS operators carry the local stations of their viewers, which is likely to hasten audience ero­sion at the local level. News Corporation's ability to drive up the cost of cable TV through the pricing of its many channels (to bring customers to DirectTV) also poses a new threat to the U.S. cable industry. Before this merger, the top four commercial satellite operators ran nearly half the world's satellites; this concentration of control will now increase.

In all these instances, satellite technology has called into question conventional notions of the nation-state. Geographic borders may be insufficient definitions of culture and nationality in an era of electronic informa­tion, beamed from multiple sources into the sky and down again into almost any location. International TV journalists, for example, no longer needed the permis­sion of local authorities to transmit television news stories to the world-by 2003, briefcase-size satellite uplinks and laptop computer video editing had made such transmissions common from an embattled Iraq and from the remotest conflict zones in Africa. How­ever, the rapid and unrelenting commercialization of space and nearly absolute control of satellites by a just a few large nations and corporations is increasingly perceived as a threat to the global majority, living in developing countries, to communicate freely and influ­ence their own cultures.