Defense Satellite Communications System
Encyclopedia
The Defense Satellite Communications System (DSCS) provides the United States
with military communications to support globally distributed military users. DSCS will be 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 STS-51J. According to the USAF, in early 2008 most of the satellites were still working.
satellite communications
. DSCS III satellites currently exceed their 10-year design life.
DSCS II provided secure voice
and data communications for the U.S. military
. 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 cell
s which produced 535 watt
s. Three NiCd batteries
provided electrical power and it was supported by a hydrazine
propulsion subsystem.
The communications payload included two 20-watt X-band channels. The transponder
s were supported by steerable narrow beam antenna
s and drive mechanism for communications privacy.
File:DSCS 2 diagram.PNG|DSCS-2 diagram
File:DSCS 3 diagram.PNG|DSCS-3 diagram
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
with military communications to support globally distributed military users. DSCS will be replaced by the Wideband Global SATCOM system
Wideband Global SATCOM system
The Wideband Global SATCOM system is a satellite communications system planned for use in partnership by the United States Department of Defense and the Australian Department of Defence. The system is composed of the Space Segment satellites, the Terminal Segment users and the Control Segment...
. A total of 14 DSCS III satellites were launched between the early 1980s and 2003. Two satellites were launched aboard the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
Atlantis
Space Shuttle Atlantis
The Space Shuttle Atlantis is a retired Space Shuttle orbiter in the Space Shuttle fleet belonging to the National Aeronautics and Space Administration , the spaceflight and space exploration agency of the United States...
in 1985 during STS-51J. According to the USAF, in early 2008 most of the satellites were still working.
Background
DSCS went though three major phases. Since the first launch, DSCS has been the "workhorse" of militaryMilitary satellite
A military satellite is an artificial satellite used for a military purpose, often for gathering intelligence, as a communications satellite used for military purposes, or as a military weapon.-Description:*Star Wars program...
satellite communications
Communications satellite
A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...
. DSCS III satellites currently exceed their 10-year design life.
DSCS II
Circuit switching
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
and data communications for the U.S. military
Military of the United States
The United States Armed Forces are the military forces of the United States. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard.The United States has a strong tradition of civilian control of the military...
. The program was managed by the Defense Communications Agency (DCA), now the Defense Information Systems Agency
Defense Information Systems Agency
The Defense Information Systems Agency is a United States Department of Defense agency that provides information technology and communications support to the President, Vice President, Secretary of Defense, the military Services, and the Combatant Commands.As part of the Base Realignment and...
.
The space vehicles were spin stabilized with a de-spun antenna platform. The body was mounted with solar cell
Solar cell
A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....
s which produced 535 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s. Three NiCd batteries
Nickel-cadmium battery
The nickel–cadmium battery ' is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes....
provided electrical power and it was supported by a hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
propulsion subsystem.
The communications payload included two 20-watt X-band channels. The transponder
Transponder
In telecommunication, the term transponder has the following meanings:...
s were supported by steerable narrow beam antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
s and drive mechanism for communications privacy.
Photo gallery
File:DSCS 2 diagram.PNG|DSCS-2 diagram
File:DSCS 3 diagram.PNG|DSCS-3 diagram