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The Satellite Data System (SDS) is a system of United States military communications satellites. The United States Armed Forces are the overall unified military forces of the United States A communications satellite (sometimes abbreviated to comsat) is an artificial Satellite stationed in space for the purposes of Telecommunications. At least two generations have been used: SDS-1 from July 1976 to November 1995, and SDS-2 from 1989 to the present. SDS satellites have a highly elliptical orbit, going from about 300 kilometers at perigee to roughly 39,000 km at apogee in order to allow communications with polar stations that cannot contact geosynchronous satellites. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from A geographical pole, or geographic pole, is either of two fixed points on the surface of a spinning body or Planet, at 90 degrees from the Equator, based A geosynchronous orbit is an Orbit around the Earth with an Orbital period matching the Earth's sidereal rotation period The high apogee meant that the polar regions were visible for long amounts of time, and only two satellites were required in order to achieve constant communications ability. The SDS satellites were constructed by Hughes Aircraft. Hughes Aircraft Company was a major aerospace and defense company founded by Howard Hughes.

The primary purpose of the SDS satellites is to relay imagery from low-flying reconnaissance satellites to ground stations in the United States. A spy satellite (officially referred to as a reconnaissance satellite) is an Earth observation satellite or Communications satellite deployed for

Each SDS-1 satellite had 12 channels available for ultra-high frequency communication. They were cylindrical in shape, roughly 25 feet (7. A cylinder is one of the most basic curvilinear geometric shapes the Surface formed by the points at a fixed distance from a given Straight line, the axis 6 m) long. 980 watts of electrical power were available from solar panels and batteries. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. In the field of Photovoltaics, a photovoltaic module is a packaged interconnected assembly of photovoltaic cells also known as Solar cells An installation of In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy The SDS-1 had a mass of 1385 pounds (630 kilograms) and was launched on Titan-3B rockets. The pound or pound-mass (abbreviation lb, lbm, or sometimes in the United States #) is a unit of Mass Titan was a family of US expendable Rockets used between 1959 and 2005 The SDS-1 satellites had similar orbits to the Air Force's Jumpseat ELINT satellites. Jumpseat, also known as AFP-711 is reportedly a code name for a class of SIGINT Reconnaissance satellites operated by the National Reconnaissance Office

The SDS-2 is significantly more massive at 5150 pounds (2335 kg), with three separate communication dishes, including one for a K band downlink. NATO K band The NATO K band is defined as a frequency band between 20 and 40 GHz (7 Two dishes are 15 feet (4. A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit 5 meters) in diameter, while the third is 6. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International 6 feet (2 m) in diameter. The solar arrays generate 1238 watts of power. It is believed that the Space Shuttle has been used to launch one or two satellites, possibly one on STS-28, and another on STS-53. NASA 's Space Shuttle, officially called Space Transportation System ( STS) is the United States government's current manned Launch STS-28 was the fourth shuttle mission dedicated to United States Department of Defense, and first flight of Columbia since mission STS-61-C. STS-53 was a Space Shuttle ''Discovery'' mission in support of the United States Department of Defense. Other launches have used the Titan-4 rocket.

Quasar is the rumored code name for the communications satellite.

A recent Quasar may have been launched into a high-apogee orbit from Cape Canaveral on August 31, 2004 by an Atlas 2AS rocket. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from Cape Canaveral from the Spanish Cabo Cañaveral, is a headland in Brevard County Florida, United States, near the center of that Events 1056 - Byzantine Empress Theodora becomes ill dying suddenly a few days later without children to succeed the Throne "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again "

Contents

Launches

SDS-1

SDS-2

SDS-3

References

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