Military Strategic and Tactical Relay satellite
Encyclopedia
Milstar, originally meaning Military Strategic and Tactical Relay, is a constellation
of communications satellites in geostationary orbit
, which are operated by the United States
Air Force
, and provide secure and jam resistant worldwide communications to meet the requirements of the Armed Forces of the United States. Six spacecraft were launched between 1994 and 2003, of which five are operational, and the sixth was lost in a launch failure.
rocket. It was followed by a second spacecraft on 7 November 1995. The first two satellites were Block I spacecraft, also known as Milstar Development Flight Satellites, or Milstar-DFS. The four later satellites were Block II spacecraft, which featured an additional medium data-rate payload. The first Block II satellite was launched on 30 April 1999, using a Titan IV(401)B
rocket. Due to a programming error affecting the Centaur
upper stage of its carrier rocket, it was placed into a lower orbit than had been planned, and it could not be raised into its operational orbit. It was the third consecutive, and last, failure of a Titan IV rocket. The remaining three satellites were launched on 27 February 2001, 15 January 2002, and 8 April 2003.
The Milstar system consists of three segments; the space segment which consists of the five satellites, ground terminals and users, and stations to command and control the satellites. The Military Satellite Communications Systems Wing
(MILSATCOM) division of the United States Air Force Space Command Space and Missile Systems Center
, located at Los Angeles AFB was responsible for development and acquisition of the Milstar space and mission control segments. The Electronic Systems Center
at Hanscom AFB
is responsible for the US Air Force portion of the terminal segment development and acquisition. The 4th Space Operations Squadron
at Schriever AFB and the 148th Space Operations Squadron
at Vandenberg AFB are responsible for providing real-time satellite control and communications payload management.
In August 2010 control of the Milstar system was transferred to the Advanced Extremely High Frequency
program, in preparation for the launch of the first AEHF satellite, USA-214
. Advanced Extremely High Frequency satellites are intended to replace Milstar.
, at a cost of US$800 million each. Each satellite has a design life of 10 years. Six were built, of which five successfully reached their operational geostationary orbit
s, and remain in service. Launches were made using Titan IV
rockets with Centaur upper stages, and all six occurred from Space Launch Complex 40 at the Cape Canaveral Air Force Station
. The satellites are designed to provide communications which are hard to detect and intercept, and to be survivable in the event of nuclear warfare
.
The spacecraft have a mass of 4500 kilograms (9,920.8 lb), and are equipped with solar panels which generate eight kilowatts of electric power
to power its transponders
. Both Block I and Block II satellites provide low data-rate communications at bandwidths between 75 bit/s and 2,400 bit/s, whilst the Block II spacecraft can also provide medium data-rate communications between 4.8 kbit/s and 1.544 Mbit/s. The satellites' uplinks operate in the Q band
, whilst their downlinks operate within the Ka band
. Both of these frequencies correspond to the super high frequency
radio band.
Each Milstar satellite serves as a switchboard
to direct traffic between terminals on the Earth. The satellites process the signals transmitted to them, and can link with other Milstar satellites through crosslinks, to reduce the requirement for ground-controlled switching. The spacecraft are used for encrypted
voice
, data, teletype, and facsimile
communications, which are interoperable between the United States Army
, Navy
, Air Force
, Marine Corps
, and Coast Guard
.
Satellite constellation
A group of artificial satellites working in concert is known as a satellite constellation. Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronised so that they overlap well in coverage and...
of communications satellites in geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...
, which are operated by the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
, and provide secure and jam resistant worldwide communications to meet the requirements of the Armed Forces of the United States. Six spacecraft were launched between 1994 and 2003, of which five are operational, and the sixth was lost in a launch failure.
History
The first Milstar satellite was launched on 7 February 1994 aboard the first Titan IV(401)ATitan IV
The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The...
rocket. It was followed by a second spacecraft on 7 November 1995. The first two satellites were Block I spacecraft, also known as Milstar Development Flight Satellites, or Milstar-DFS. The four later satellites were Block II spacecraft, which featured an additional medium data-rate payload. The first Block II satellite was launched on 30 April 1999, using a Titan IV(401)B
Titan IV
The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The...
rocket. Due to a programming error affecting the Centaur
Centaur (rocket stage)
Centaur is a rocket stage designed for use as the upper stage of space launch vehicles. Centaur boosts its satellite payload to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity...
upper stage of its carrier rocket, it was placed into a lower orbit than had been planned, and it could not be raised into its operational orbit. It was the third consecutive, and last, failure of a Titan IV rocket. The remaining three satellites were launched on 27 February 2001, 15 January 2002, and 8 April 2003.
The Milstar system consists of three segments; the space segment which consists of the five satellites, ground terminals and users, and stations to command and control the satellites. The Military Satellite Communications Systems Wing
Military Satellite Communications Systems Wing
The United States Air Force's Military Satellite Communications Systems Wing is an organization headquartered at Los Angeles AFB, California...
(MILSATCOM) division of the United States Air Force Space Command Space and Missile Systems Center
Space and Missile Systems Center
The Space and Missile Systems Center is a part of Air Force Space Command of the United States Air Force. SMC is the Air Force’s product center for the development and acquisition of space and missile systems...
, located at Los Angeles AFB was responsible for development and acquisition of the Milstar space and mission control segments. The Electronic Systems Center
Electronic Systems Center
Electronic Systems Center is a product center of Air Force Materiel Command headquartered at Hanscom Air Force Base, Massachusetts. Its mission is to develop and acquire command and control, communications, computer, and intelligence systems. ESC consists of professional teams specializing in...
at Hanscom AFB
Hanscom Air Force Base
Hanscom Air Force Base is a United States Air Force base located approximately south-southwest of Bedford, Massachusetts. The facility is a joint use civil airport/military base with Hanscom Field which provides general aviation and charter service.The host unit at Hanscom is the non-flying...
is responsible for the US Air Force portion of the terminal segment development and acquisition. The 4th Space Operations Squadron
4th Space Operations Squadron
The United States Air Force's 4th Space Operations Squadron is a satellite operations unit located at Schriever AFB, Colorado...
at Schriever AFB and the 148th Space Operations Squadron
148th Space Operations Squadron
The United States Air Force's 148th Space Operations Squadron is a satellite control unit located at Vandenberg AFB, California. The 148th SOPS is tasked with back-up command and control of the MILSTAR satellite constellation.-Mission:...
at Vandenberg AFB are responsible for providing real-time satellite control and communications payload management.
In August 2010 control of the Milstar system was transferred to the Advanced Extremely High Frequency
Advanced Extremely High Frequency
Advanced Extremely High Frequency is a series of communications satellites operated by the United States Air Force Air Force Space Command. The spacecraft will be used to relay secure communications for the Armed Forces of the United States, the British Armed Forces, the Canadian Forces and the...
program, in preparation for the launch of the first AEHF satellite, USA-214
USA-214
USA-214, known before launch as Advanced Extremely High Frequency 1 or AEHF SV-1, is a military communications satellite operated by the United States Air Force...
. Advanced Extremely High Frequency satellites are intended to replace Milstar.
Characteristics
Milstar satellites provide secure, jam resistant, worldwide communications to meet the requirements of the United States military. They were built by Lockheed Martin Missiles and Space CorporationLockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
, at a cost of US$800 million each. Each satellite has a design life of 10 years. Six were built, of which five successfully reached their operational geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...
s, and remain in service. Launches were made using Titan IV
Titan IV
The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The...
rockets with Centaur upper stages, and all six occurred from Space Launch Complex 40 at the Cape Canaveral Air Force Station
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...
. The satellites are designed to provide communications which are hard to detect and intercept, and to be survivable in the event of nuclear warfare
Nuclear warfare
Nuclear warfare, or atomic warfare, is a military conflict or political strategy in which nuclear weaponry is detonated on an opponent. Compared to conventional warfare, nuclear warfare can be vastly more destructive in range and extent of damage...
.
The spacecraft have a mass of 4500 kilograms (9,920.8 lb), and are equipped with solar panels which generate eight kilowatts of electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
to power its transponders
Transponder (Satellite communications)
A communications satellite’s transponder, is the series of interconnected units which form a communications channel between the receiving and the transmitting antennas .A transponder is typically composed of:...
. Both Block I and Block II satellites provide low data-rate communications at bandwidths between 75 bit/s and 2,400 bit/s, whilst the Block II spacecraft can also provide medium data-rate communications between 4.8 kbit/s and 1.544 Mbit/s. The satellites' uplinks operate in the Q band
Q band
The Q band of the microwave part of the electromagnetic spectrum and ranges from 33 to 50 GHz. It sits above, and partly overlaps with, the U.S. IEEE designated Ka band . It sits below the U.S...
, whilst their downlinks operate within the Ka band
Ka band
The Ka band covers the frequencies of 26.5–40 GHz. The Ka band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above" — in other words, the band directly above the K-band...
. Both of these frequencies correspond to the super high frequency
Super high frequency
Super high frequency refers to radio frequencies in the range of 3 GHz and 30 GHz. This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from ten to one centimetres....
radio band.
Each Milstar satellite serves as a switchboard
Switchboard
The term switchboard, when used by itself, may refer to:*Telephone switchboard*Electric switchboard*Printed circuit board*Mixing console*In computing, Switch board...
to direct traffic between terminals on the Earth. The satellites process the signals transmitted to them, and can link with other Milstar satellites through crosslinks, to reduce the requirement for ground-controlled switching. The spacecraft are used for encrypted
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
voice
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
, data, teletype, and facsimile
Facsimile
A facsimile is a copy or reproduction of an old book, manuscript, map, art print, or other item of historical value that is as true to the original source as possible. It differs from other forms of reproduction by attempting to replicate the source as accurately as possible in terms of scale,...
communications, which are interoperable between the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
, Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
, Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
, Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
, and Coast Guard
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...
.
Spacecraft
| Name | Block | Launch date/time (UTC) | COSPAR ID International Designator The International Designator, also known as COSPAR designation, and in the United States as NSSDC ID, is an international naming convention for satellites... |
Rocket | Remarks |
|---|---|---|---|---|---|
| USA-99 | Block I | 1994-02-07, 21:47:01 | 1994-009A | Titan IV(401)A Titan IV The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The... |
|
| USA-115 | Block I | 1995-11-06, 05:15:01 | 1995-060A | Titan IV(401)A Titan IV The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The... |
|
| USA-143 | Block II | 1999-04-30, 16:30:00 | 1999-023A | Titan IV(401)B Titan IV The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The... |
Launch failure |
| USA-157 | Block II | 2001-02-27, 21:20 | 2001-009A | Titan IV(401)B Titan IV The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The... |
|
| USA-164 | Block II | 2002-01-16, 00:30:00 | 2002-001A | Titan IV(401)B Titan IV The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The... |
|
| USA-169 | Block II | 2003-04-08, 13:43:00 | 2003-012A | Titan IV(401)B Titan IV The Titan IV family of space boosters were used by the U.S. Air Force. They were launched from Cape Canaveral Air Force Station, Florida, and Vandenberg Air Force Base, California. At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."The... |
|
See also
- Advanced Extremely High FrequencyAdvanced Extremely High FrequencyAdvanced Extremely High Frequency is a series of communications satellites operated by the United States Air Force Air Force Space Command. The spacecraft will be used to relay secure communications for the Armed Forces of the United States, the British Armed Forces, the Canadian Forces and the...
- Defense Satellite Communications SystemDefense Satellite Communications SystemThe Defense Satellite Communications System 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...
- Transformational Satellite Communications SystemTransformational Satellite Communications SystemThe Transformational Satellite Communications System program was a United States Department of Defense program sponsored by the U.S. Air Force for a secure, high-capacity global communications network serving the Department of Defense, NASA and the U.S. Intelligence Community...
- Wideband Global SATCOM systemWideband Global SATCOM systemThe 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...