This article needs additional citations for verification .(February 2014) |
Dong Fang Hong 2 (also romanised as Dongfanghong 2) was the primary television satellite used by China during the later part of the 20th century. It was developed at the Chinese Academy of Space Technology (CAST) and had a design life 4.5 years. The first operational satellite in this group was launched into a geosynchronous orbit on 8 April 1984.
Three satellites orbited in geosynchronous orbits at 87.5°, 110.5°, and 98.0° east. A fourth satellite failed to achieve a stable orbit due to a problem with the third stage. [1]
Operating under the name Dong Fang Hong 2, the Shiyong Tongbu Tongxing Weixing (STTW, Chinese :實用定位通訊衛星, literally Operational Geostationary Communications Satellite) was the designation of a family of indigenous Chinese communications satellites developed under the Project 331 initiative of the late 1970s and early 1980s. [2] Being able to provide both civilian and military long distance telephony, in addition to satellite television, the initiative was promoted by the senior Chinese leadership, most notably Deng Xiaoping and Zhou Enlai, [2] as a means to improve the communications infrastructure of the country, especially in mountainous and hard to reach areas. Building on work that had been ongoing since the 1960s Mao gave his assent to the project in April 1975. [2] The launch vehicle for the satellites was the Long March 3 with which it was developed in parallel and conjunction as part of Project 331. [2] In order to achieve a geostationary orbit, in addition to the normal three stages of the Long March 3, the STTW required a small solid propellant apogee kick motor. [2]
As part of the development program two proof of technology demonstrators were launched (Shiyan Tongbu Tongxing Weixing, "Test Geostationary Communications Satellite"). [2] The first of these launches in January 1984 was a failure when the second burn of the hydrogen fuelled cryogenic third stage engine, intended to boost the satellite from low Earth orbit (LEO) into a geostationary transfer orbit (GTO), failed. [2] However, despite being stranded in low Earth orbit, available telemetry indicated that the satellite itself was sound. The launch of the second test satellite was brought forward in April 1984, and this time both launch vehicle and satellite functioned as intended. [2] Providing 200 telephone lines, and fifteen radio and television channels, [2] the Shiyan Weixing demonstrated the utility of a communications satellite to link the developed coastal regions of Eastern China with the inhospitable and inaccessible regions of Western China.
Functioning until 1988, when it was parked in a graveyard orbit, Shiyan Weixing paved the way for the operational Shiyong Weixings, which remained China's primary communications satellite until replaced by the Dong Fang Hong 3.
Satellite | Construction | Date of launch | Launch vehicle | Status | Notes |
---|---|---|---|---|---|
STTW-T1 | 29 January 1984 | Long March 3 | Inactive | Also known as DFH-2 1. Proof of technology test satellite. Failed to achieve geosynchronous orbit, however the satellite was tested as far as possible and was found to be functioning, and because of this the launch was considered to be only a partial failure or partial success. | |
STTW-T2 | 8 April 1984 | Long March 3 | Inactive | Also known as DFH-2 2. Proof of technology test satellite. | |
STTW-T3 | 1 February 1986 | Long March 3 | Inactive | Also known as DFH-2 3. Proof of technology test satellite. | |
STTW-1 | 7 March 1988 | Long March 3 | Inactive | Also known as DFH-2A 1, ZX-1 and ChinaSat 1. [3] | |
STTW-2 | 22 December 1988 | Long March 3 | Inactive | Also known as DFH-2A 2, ZX-2 and ChinaSat 2. [3] | |
STTW 3 | 4 February 1990 | Long March 3 | Inactive | Also known as DFH-2A 3, ZX-3 and ChinaSat 3. [3] | |
STTW-4 | 28 December 1991 | Long March 3 | Failure | Also known as DFH-2A 4, ZX-4 and ChinaSat 4. [3] | |
The satellite was cylindrical with a height of 8.5 m (28 ft), a diameter of 2.1 m (6 ft 11 in) and weighed 441 kg (972 lb).
The Dongfanghong 2A satellite used a parabolic communications antenna mounted to the top of the satellite for broadcast purposes. The antenna could be rotated to keep it aligned with the Earth. Twenty-thousand solar cells were mounted to the satellite to provide power. This was China's first successful use of photovoltaic technology. [4]
A geosynchronous orbit is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds. The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day. Over the course of a day, the object's position in the sky may remain still or trace out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity. A circular geosynchronous orbit has a constant altitude of 35,786 km (22,236 mi).
A geostationary orbit, also referred to as a geosynchronous equatorial orbit (GEO), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation.
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit 22,236 miles (35,785 km) above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.
Syncom started as a 1961 NASA program for active geosynchronous communication satellites, all of which were developed and manufactured by the Space and Communications division of Hughes Aircraft Company. Syncom 2, launched in 1963, was the world's first geosynchronous communications satellite. Syncom 3, launched in 1964, was the world's first geostationary satellite.
Dong Fang Hong 1, in the western world also known as China 1 or PRC 1, was the first space satellite of the People's Republic of China (PRC), launched successfully on 24 April 1970 as part of the PRC's Dongfanghong space satellite program. It was a part of the "Two Bombs, One Satellite" program. At 173 kg (381 lb), it was heavier than the first satellites of other countries. The satellite carried a radio transmitter which broadcast the then de facto national anthem of the same name. The broadcast lasted for 20 days while in orbit.
Dongfanghong was a satellite program of the People's Republic of China. The program started in August 1965 as Project 651—a less ambitious successor to the earlier Project 581—with the goal of launching a satellite heavier than both Sputnik 1 and Explorer 1 into space, and developing all the necessary technologies to do so.
Satellite Internet access is Internet access provided through communication satellites; if it can sustain high speeds, it is termed satellite broadband. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using the Ku band to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space.
Fēngyún are China's meteorological satellites. Launched since 1988 into polar Sun-synchronous and geosynchronous orbit, each three-axis stabilized Fengyun satellite is built by the Shanghai Academy of Spaceflight Technology (SAST) and operated by the China Meteorological Administration (CMA). To date, China has launched twenty-one Fengyun satellites in four classes. Fengyun 1 and Fengyun 3 satellites are in polar, Sun-synchronous orbit and Low Earth orbit while Fengyun 2 and 4 are geosynchronous orbit.
AMOS-1, then Intelsat 24, was a commercial communications satellite which was operated by Spacecom as AMOS-1, for Affordable Modular Optimized Satellite and formed part of the AMOS series of satellites. It was the first Israeli civilian communications satellite, and was initially positioned at 4° West longitude in geostationary orbit. Then in September 2011, it was moved to 31° East.
IndoStar-1, also known as Cakrawarta-1, was a communication satellite that was launched the evening of November 12, 1997 at 21:48 GMT aboard an Ariane 44L-3 rocket from Kourou, French Guiana. As the first direct broadcasting satellite (DBS) in Asia, IndoStar-1 would initiate a new communication service for Indonesian society such as direct-to-home television.
A geosynchronous satellite is a satellite in geosynchronous orbit, with an orbital period the same as the Earth's rotation period. Such a satellite returns to the same position in the sky after each sidereal day, and over the course of a day traces out a path in the sky that is typically some form of analemma. A special case of geosynchronous satellite is the geostationary satellite, which has a geostationary orbit – a circular geosynchronous orbit directly above the Earth's equator. Another type of geosynchronous orbit used by satellites is the Tundra elliptical orbit.
ChinaSat is the brand name of communications satellites operated by China Satellite Communications.
The Long March 3B, also known as the CZ-3B and LM-3B, is a Chinese orbital launch vehicle. Introduced in 1996, it is launched from Launch Area 2 and 3 at the Xichang Satellite Launch Center in Sichuan. A three-stage rocket with four strap-on liquid rocket boosters, it is the heaviest variant of the Long March 3 rocket family, and is mainly used to place communications satellites and navigation satellites into geosynchronous orbits.
The initialism STTW may stand for:
Paksat-1R is a geosynchronous, communications satellite that was manufactured by China Great Wall Industry Corporation (CGWIC) and operated by the Space and Upper Atmosphere Research Commission (SUPARCO), an executive space authority of the Government of Pakistan.
Sino Satellite Communications Co., Ltd. known also as SinoSat is a Chinese company.
Dong Fang Hong was a space satellite program in the People's Republic of China.
Alcomsat-1 is the first Algerian communications satellite. It was carried by Chinese launcher Long March 3B from the Xichang Satellite Launch Center, located in Sichuan Province, 2,200 km southwest of Beijing.
Shijian is a series of satellites built and operated by the People's Republic of China. Some Shijian-series satellites have drawn significant concerns from the United States government and space observers who cite unannounced launches, undisclosed sub-satellites deployed in orbit, unusual orbital maneuvers, and demonstrated rendezvous proximity operations (RPO) including the close inspection and towing of other satellites.
Tongxin Jishu Shiyan is a Chinese military satellite program operating in geostationary orbit (GEO). TJS satellites are manufactured by the Shanghai Academy of Spaceflight Technology (SAST) and launched from Xichang Satellite Launch Center (XSLC) in China's southern Sichuan Province. TJS is likely the cover name for multiple geostationary military satellite programs and should not be confused with the similarly named Shiyan satellite program.