Millitary Sattelites

[Super Falcon]

as we all know todyas war fought on cummunication and wars can be won with good communications with weaon system where these sattelites can come to play for modern digital warfare.

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The first in a new generation of military communications satellites that will aid British troops around the globe was launched in 1998. The rocket carried the UK Ministry of Defence's Skynet 4D satellite.

SECURE COMMUNICATIONS SATELLITE
The new spacecraft will replace earlier models that were launched between 1988 and 1990, which played an important role in the Gulf War and currently provide a crucial communications link for British forces in Bosnia.

The $150 million spacecraft was released into a temporary egg-shaped orbit. It later used its own rocket motor to reach a final orbit 22,300 miles above the equator.

The service provided by the satellite will be used primarily by the UK's armed forces, government departments, agencies and other organisations that require secure communications. The service will also be available to approved defence and other governmental users from overseas countries and also multinational organisations.

Two more Skynet satellites are to ride into orbit on European Ariane rockets launched from French Guiana. The Skynet 4F military communications satellite was launched on February 2001.

PROJECT TIMESCALE

Skynet 4A, 4B and 4C were launched between 1988 and 1990. Skynet 4D and 4E were launched in 1998.

SKYNET 4F
The UK Ministry of Defence's latest and last Skynet 4F spacecraft, designed and built by Astrium in the UK to provide British military satellite communications, was launched from Kourou in French Guiana. Skynet 4F was carried inside the Spelda dual launch structure whilst the Sicral satellite, built by Alenia Spazio for the Italian Ministry of Defence, was on top and so was released first. Astrium's "delivery-in-orbit" contract includes the launch of the satellite and also provides for operational control and in-orbit testing of the satellite prior to hand-over to the customer.

A variety of spot and global beams enables the Skynet 4 satellite to serve a widely dispersed and extensive inventory of Earth stations on land, sea and in the air, ranging from small man-portable radio sets and aircraft terminals to rugged systems on naval vessels and submarines and the large anchor stations on land. Skynet 4 employs signal processing and anti-jamming features and its ability to survive in the harshest of electronic warfare environments is extremely important.

The design of the Skynet, stage 2 satellites is derived from the earlier stage 1 spacecraft and incorporates a number of changes to provide increased operational flexibility and to incorporate the benefits of more modern technology.

SPACECRAFT PLATFORM
The new spacecraft platform includes a repackaged telemetry, tracking and control (TT&C) system, increased autonomous operation, improved electrical power system and enhanced reaction control system.

COMMUNICATIONS

The communications payload is provided with tuneable UHF. The power of each of the two UHF transponders has been increased to 50W each, serving one channel of 25kHz. The antenna is the Earth cover helical model. The system is also equipped with a steerable high power spot and a SHF transmit and receive antenna .


As an enhanced version of the three Skynet 4, Stage 1 satellites and the two similar NATO IV spacecraft, the modified communications payload incorporates steerable antennas for SHF spot beam communications. It also provides increased power and a superior anti-jamming capability whilst, at UHF, a fully tuneable system offers increased flexibility.


CONTRACTORS

Astrium is both the prime contractor and payload contractor for the UK Ministry of Defence's Skynet 4 satellites.

 

[Super Falcon]

Lockheed Martin Space Systems, Hughes Space and Communications and TRW have formed a National Team to build the Department of Defense's (DOD) next generation of highly secure communication satellites known as the Advanced Extremely High Frequency system.

The Advanced EHF programme provides the follow-on capability to the Milstar satellite programme. It provides the basis for the next generation military communications satellite system, for survivable, jam-resistant, worldwide, secure, communications for the strategic and tactical warfighter. The system replenishes the Milstar constellation in the EHF band.

MILSATCOM SATELLITE PROGRAMME
The MILSATCOM Programme Office, located at the Space and Missile Systems Centre, Los Angeles Air Force Base, California, will manage the Advanced EHF contract and is the lead agency for ensuring the secure communications capabilities of this system are made available to the warfighter.

The Advanced EHF Programme is the follow-on to the DOD’s Milstar highly secure communication satellite programme, which currently has two Milstar I spacecraft in orbit. Formation of the new team accelerated development of the new system by 18 months. The earlier deployment of Advanced EHF will help bridge the gap in military communication coverage caused by the loss of the third Milstar satellite, launched in 1999.

Under the National Team contract, the production phase of the programme is scheduled to begin in April 2001, with the first of five satellites to be launched late in 2004. The estimated contract value of the Advanced EHF programme is $2.5 billion. Earlier deployment of the system will help the military by putting vital tactical capabilities into the hands of US armed forces sooner, increasing both communications capacity and coverage.

EXTREMELY HIGH FREQUENCY SATELLITE CONSTELLATION
The fully operational Advanced EHF constellation will consist of four crosslinked satellites, providing coverage of the Earth from 65° north latitude to 65° south. These satellites will provide more data throughput capability and coverage flexibility to regional and global military operations than ever before. The fifth satellite built could be used as a spare or launched to provide additional capability to the envisioned constellation.

According to Lockheed Martin Space, Advanced EHF will benefit from the team's combined leadership in related military and commercial technologies to reduce satellite size and cost while significantly boosting performance and reduced programme risks.

SATELLITE SYSTEMS INTEGRATION
Lockheed Martin will contribute its systems integration, ground systems and satellite expertise to the project. TRW will design and produce the satellites' digital processing subsystem, which controls all onboard switching and processing of messages. TRW will also provide the satellites' nulling antenna subsystem, which prevents adversaries from jamming signals to and from the satellite, and the inter-satellite crosslinks with support from Hughes for the crosslink reflectors. The crosslink subsystem enables Advanced EHF satellites to send messages directly to each other, without the need for a ground station.

PAYLOAD, ELECTRONICS AND ANTENNAS
Hughes will lead the payload effort and will be responsible for payload integration, as well as production of RF electronics and phased array antennas. According to the company, Hughes’ commercial and government programme experience in payload system integration, RF electronics and phased array antennas will ensure the warfighter receives a state-of-the-art system in the shortest possible time.

The higher data rates permit transmission of tactical military communications such as real-time video, battlefield maps and targeting data. To accomplish this, Advanced EHF adds new higher data rate modes to the low data rate and medium data rate modes of Milstar II satellites. The higher data rate modes will provide data rates up to 8.2 million bits of data per second to future Advanced EHF Army terminals. Each Advanced EHF satellite employs more than 50 communications channels via multiple, simultaneous downlinks. For global communications, the Advanced EHF system uses inter-satellite crosslinks, eliminating the need to route messages via terrestrial systems

CONTRACTORS

On the new National Team, Lockheed Martin will serve as overall system integrator and prime contractor, issuing subcontracts to both Hughes and TRW. The roles and responsibilities of each team member will take advantage of their strengths in building highly secure military communications satellites

 

[Super Falcon]

The Air Force launched a $800 million military communication satellite into orbit in late February 2001, after problems with electronic equipment, scheduling conflicts and rocket safety concerns were overcome. Once it reaches its final orbit 22,300 miles high and has been checked for six months, the Milstar will provide jam-proof, ultra high frequency and high data rate communications, both tactical and strategic, over the next decade. It will instantly link bombers, missiles and submarines, fighter pilots and troops on the ground.

MILSTAR SATELLITE COMMUNICATIONS CONSTELLATION
Milstar is a military satellite communications system that provides the Department of Defense and troops in the field with reliable, secure, jam-proof communications between fixed-site, mobile and portable terminals.

The Milstar system is composed of three segments. These are the space segment, comprised of six satellites, the terminal segment, composed of communications terminals installed on ships, submarines, aircraft and vehicles, and the mission control segment, based at Falcon Air Force Base, Colorado Springs, Colorado.

The Milstar programme is led by the MILSATCOM Joint Program Office at the Air Force Space and Missile Systems Center in El Segundo, CA. The in-orbit system is managed by the US Space Command at Falcon Air Force Base, CO.

MILSTAR BLOCK II SPACECRAFT
Of the five Milstar satellites that constitute the constellation, two first-generation Milstar Block I were deployed in 1994 and 1995. Block I satellites feature a low data rate payload built by TRW Space and Electronics Group, El Segundo, CA, and two satellite crosslink antennas, built by Boeing Satellite Systems, El Segundo, CA. Both of the Milstar I spacecraft, DFS-1 and DFS-2, were launched on Lockheed Martin Titan boosters from Cape Canaveral Air Station, FL.

Three subsequent launches will each deploy a second-generation Milstar Block II spacecraft (DFS-4 through DFS-6), which carry the low data rate payload and a medium-data-rate payload. DFS-4 through DFS-6 will operate in conjunction with both Block I satellites.

COMMUNICATION NETWORKS
Milstar is the first satellite communications system of any kind that uses signal processing algorithms on the satellites, allowing commanders from every service to establish customised networks within minutes. Current networks must be configured on the ground, require multiple remote locations and can take weeks to establish using existing commercial and military systems.

Milstar communicates via terminals that are compatible among all the military services, including shipborne, man-portable, vehicle-mounted and carried in command and control aircraft. Each terminal transmits and receives voice and data in the Extremely High Frequency and Super High Frequency spectrum. The low data rate payload is designed to transmit voice, data and fax information at 75bps to 2,400bps. The medium data payload, making its debut on the first Milstar II spacecraft will be able to transmit 1.5Mbps.

This combination of data rates and operational frequencies provides US military forces with capabilities not available on current Defense Satellite Communications System satellites or through commercial systems. These capabilities include immunity to jamming and interception and increased mobility for sea, air and ground forces. The Milstar satellite provides enhanced communication security by frequency hopping, which is a first for communication satellites.

CONTRACTORS

Lockheed Martin Space Systems Sunnyvale Operations, Sunnyvale, California, is the prime contractor. TRW Space and Electronics Group provided the low data rate payload. Boeing Satellite Systems provided the medium data rate payload for Milstar Block II. Space Systems Denver provides the Titan IV launch vehicle and the wide-body Centaur upper stage. Milstar launches are managed by the 45th Space Wing, Patrick Air Force Base, Florida.

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In its 61st consecutive success, an Ariane rocket lifted Italy's Sicral 1 satellite and the British Skynet 4F spacecraft into geostationary transfer orbit from Europe's Guyana Space Centre. The launch, the 139th flight of an Ariane rocket, was the first time the vehicle lifted two military spacecraft at once into orbit.

SICRAL EHF COMMUNICATIONS
Sicral 1 is Italy's first military satellite. It is designed to operate for 10 years from 16.2° east longitude and to provide communications to fixed and mobile terminals operated by Italy's military. Sicral is Europe's first venture into Extremely High Frequency (EHF) broadcast frequencies. Italian officials have said the satellite has capacity in EHF, as well as Super High Frequency and Ultra High Frequency, permitting interoperability with US and other European satellite systems.

PROJECT TIMESCALE

The project was first conceived in 1996. The launch was successfully completed in 2001.

MILITARY COMMUNICATIONS PROGRAMME
The Sicral programme has been budgeted at about €500 million ($458.8 million). In addition to the cost of the construction and launch of Sicral 1, this figure includes the construction, by Alenia Spazio, of a duplicate Sicral skeletal platform, or bus, and long-lead-time items for a Sicral 2 electronics payload. The figure also includes a Sicral ground control centre and 107 fixed and mobile terminals, including several to be placed on Italian jet-fighter aircraft. The Italian Authorities said that Sicral 2 would be built within 18 months if Sicral 1 failed to operate as designed.

The satellite that will activate the new network of military telecommunications was realised by the Sitab consortium. The consortium is constituted from Alenia Spazio (70&#37, FiatAvio (20%) and Telespazio (10%). The orbiting of Sicral successfully meets the challenge laid down to the Italian space industry in 1996 by the Defence Administration thanks to a considerable effort in terms of technology, design, organisation and construction.

It has also designed, built and integrated the satellite and its various elements, the bus, payload and antennas, as well as the telecommunications networks with the radio stations for the Mission Control Centre and Satellite Control Centre. These have been designed, built and integrated by Alenia Spazio.


LAUNCH AND PROPULSION
FiatAvio is responsible for the launch service, the satellite propulsion system and some ground equipment (time and frequency, computers and shelters). The propulsion system for Sicral, designed and built by FiatAvio gives the satellite the impulse needed for insertion in the planned geostationary orbit and for attitude control during its operational life.

BRACCIANO CONTROL CENTRE
Telespazio was made responsible by the Defence Administration for the management of all the activities necessary for the complete operability of the Bracciano Control Centre in the context of the Sicral programme. It also guarantees the full functionality of the entire system: satellite, orbital management and control centre, communication networks and terminals. Moreover, Telespazio manages the LEOP (Launch and Early Orbit Phase) activities of Sicral: the collective operational phases of satellite command and control carried out from when the spacecraft is released from the launcher up to final orbital position and required altitude.

CONTRACTORS

As prime contractor in the Sitab consortium, Alenia Spazio has co-ordinated the activities of the companies involved in the programme; approx. 150, covering virtually the entire Italian space industry.