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The Defense Satellite Communications System (DSCS) is a United States Space Force satellite constellation that provides the United States with military communications to support globally distributed military users. Beginning in 2007, DSCS is being replaced by the Wideband Global SATCOM system. A total of 14 DSCS-III satellites were launched between the early 1980s and 2003. Two satellites were launched aboard the Space Shuttle ''Atlantis'' in 1985 during the STS-51-J flight. As of 14 September 2021, six DSCS-III satellites were still operational. DSCS operations are currently run by the
In April 1960, the Advanced Research Projects Agency (ARPA) began work on the Advent program, which was intended to deliver a military communication satellite. The design concept proved too advanced for the technology of the time, and the program was cancelled in May 1962. The Initial Defense Communications Satellite Program (IDCSP) was one of two recommended follow up approaches to deliver a working satellite.
Philco (now Ford Aerospace) was contracted for the work. The IDCSP delivered a simple, spin-stabilized satellite placed into a sub-synchronous orbit that did not require station-keeping or active altitude control. The capacity was approximately 1 Mbit/s digital data.
The first launch of 7 satellites was conducted in June 1966. The system was declared operational with the 1968 launch and renamed to Initial Defense Satellite Communication System (IDSCS).
A total of 34 IDSCS satellites were built, with 8 lost in a launch failure in August 1966.
File:DSCS 2 diagram.PNG, DSCS-2 diagram
File:DSCS 3 diagram.PNG, DSCS-3 diagram
Lockheed Martin's Page on DSCSU.S. Air Force MILSATCOM - DSCSAir Force - DSCS IIINASA's National Space Science Data Center (NSSDC) - Master Catalog - Spacecraft Query
{{Use American English, date=January 2014 6 Communications satellite constellations Military communications of the United States Military satellites of the United States Spacecraft launched by Atlas rockets Spacecraft launched by Delta IV rockets Spacecraft launched by the Space Shuttle Spacecraft launched by Titan rockets Equipment of the United States Space Force Military equipment introduced in the 1960s ja:アメリカ軍の衛星通信#DSCS
The Defense Satellite Communications System (DSCS) is a United States Space Force satellite constellation that provides the United States with military communications to support globally distributed military users. Beginning in 2007, DSCS is being replaced by the Wideband Global SATCOM system. A total of 14 DSCS-III satellites were launched between the early 1980s and 2003. Two satellites were launched aboard the Space Shuttle ''Atlantis'' in 1985 during the STS-51-J flight. As of 14 September 2021, six DSCS-III satellites were still operational. DSCS operations are currently run by the 4th Space Operations Squadron
The United States Space Force's 4th Space Operations Squadron is a satellite operations unit located at Schriever Space Force Base, Colorado. 4 SOPS is part of Space Delta 8 and responsible for command and control of the Milstar/Advanced Ext ...
out of Schriever Space Force Base.
Background
DSCS went through three major phases — IDCSP (Interim Defense Communication Satellite Program), DSCS-II, and DSCS-III. Since the first launch, DSCS has been the "workhorse" of military satellite communications. All DSCS III satellites have exceeded their 10-year design life. The National Science Foundation use the DSCS satellites to provide additional bandwidth toAmundsen–Scott South Pole Station
The Amundsen–Scott South Pole Station is the United States scientific research station at the South Pole of the Earth. It is the southernmost point under the jurisdiction (not sovereignty) of the United States. The station is located on the ...
and McMurdo Station
McMurdo Station is a United States Antarctic research station on the south tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the Unit ...
on Ross Island
Ross Island is an island formed by four volcanoes in the Ross Sea near the continent of Antarctica, off the coast of Victoria Land in McMurdo Sound. Ross Island lies within the boundaries of Ross Dependency, an area of Antarctica claimed by New ...
on the continent of Antarctica.
IDCSP
In April 1960, the Advanced Research Projects Agency (ARPA) began work on the Advent program, which was intended to deliver a military communication satellite. The design concept proved too advanced for the technology of the time, and the program was cancelled in May 1962. The Initial Defense Communications Satellite Program (IDCSP) was one of two recommended follow up approaches to deliver a working satellite.
Philco (now Ford Aerospace) was contracted for the work. The IDCSP delivered a simple, spin-stabilized satellite placed into a sub-synchronous orbit that did not require station-keeping or active altitude control. The capacity was approximately 1 Mbit/s digital data.
The first launch of 7 satellites was conducted in June 1966. The system was declared operational with the 1968 launch and renamed to Initial Defense Satellite Communication System (IDSCS).
A total of 34 IDSCS satellites were built, with 8 lost in a launch failure in August 1966.
DSCS II
DSCS II, developed under Program 777 provided secure voice and data transmission for the United States Armed Forces. The program was managed by the Defense Communications Agency (DCA), now the Defense Information Systems Agency. The space vehicles were spin stabilized with a de-spun antenna platform. The body was mounted with solar cells, which produced 535 watts. Three NiCd batteries provided electrical power and it was supported by ahydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
propulsion subsystem.
The communications payload included two 20-watt X band
The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxim ...
channels. The transponders were supported by steerable narrow beam antenna
Antenna ( antennas or antennae) may refer to:
Science and engineering
* Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves
* Antennae Galaxies, the name of two collid ...
s and drive mechanism for communications privacy.
The first DSCS II launch was in 1971.
DSCS III
On 12 December 1975research and development
Research and development (R&D or R+D), known in Europe as research and technological development (RTD), is the set of innovative activities undertaken by corporations or governments in developing new services or products, and improving existi ...
contracts were awarded to General Electric and Hughes Aircraft Company
The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of Hughes Tool Company. The company was known for producing, among other produ ...
to begin DSCS III design studies, with the first Block 1 launch on 30 October 1982.
DSCS III satellites support globally distributed Department of Defense (DoD) and national security users. The final 4 of 14 satellites received Service Life Enhancement Program (SLEP) modifications. These changes provided substantial capacity improvements through higher power amplifiers, more sensitive receivers, and additional antenna connectivity options. The DSCS communications payload includes six independent Super High Frequency (SHF) transponder channels that cover a 500 MHz bandwidth. Three receive and five transmit antennas provide selectable options for Earth coverage, area coverage and/or spot beam coverage. A special purpose single-channel transponder is also on board.
DSCS III Spacecraft
Image gallery
See also
* MilstarReferences
External links
Lockheed Martin's Page on DSCS
{{Use American English, date=January 2014 6 Communications satellite constellations Military communications of the United States Military satellites of the United States Spacecraft launched by Atlas rockets Spacecraft launched by Delta IV rockets Spacecraft launched by the Space Shuttle Spacecraft launched by Titan rockets Equipment of the United States Space Force Military equipment introduced in the 1960s ja:アメリカ軍の衛星通信#DSCS