Wideband Global SATCOM system

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Artist's conception of a WGS satellite in orbit

The Wideband Global SATCOM system (sometimes called the Wideband Gapfiller Satellite system) is a satellite communications system planned for use by the United States Department of Defense (DoD). The system is composed of the Space Segment satellites, the Terminal Segment users and the Control Segment operators.^[1] DoD wideband satellite communication services are currently provided by a combination of the existing Defense Satellite Communications System (DSCS) and Global Broadcast System (GBS) satellites.^[2] According to Lt. Col. John Wagner, "A single WGS spacecraft has as much bandwidth as the entire existing DSCS constellation."^[3]

1 Mission
2 Capablilites
3 Space segment
4 Terminal segment
5 Control segment
6 References

[edit] Mission

The Wideband Global SATCOM (WGS) satellites are key elements of a system that increases the communications capabilities of U.S. and allied nation's military forces deployed around the globe. WGS supports the U.S. Department of Defense's warfighting information exchange requirements, enabling execution of tactical command and control, communications, and computers; intelligence, surveillance, and reconnaissance (C4ISR); battle management; and combat support information. WGS also augments the current Ka-band Global Broadcast Service (on UHF F/O satellites) by providing additional information broadcast capabilities. The combination of the Wideband Global Satellites, DSCS satellites, GBS payloads, wideband payload and platform control assets, and earth terminals operating with them has been referred to as the Interim Wideband System (IWS).^[who?] It provides services to the US Department of Defense and the Ministry of Defense for Canada as well as other Government and Allied users under unstressed conditions. The IWS System supports continuous 24 hour per day wideband satellite services to tactical users and some fixed infrastructure users. Limited protected services will be provided under conditions of stress to selected users employing terrestrial modems capable of providing protection against jamming. The combined wideband satellite communications system consists of space vehicles of multiple types, control terminals and facilities, and user terminals.

[edit] Capablilites

The new Wideband Global SATCOM (WGS) satellites will complement the DSCS III Service Life Enhancement Program (SLEP) and GBS payloads, and offset the eventual decline in DSCS III capability. WGS will offer 4.875 GHz of instantaneous switchable bandwidth, thus each WGS can supply more than 10 times the capacity of a DSCS III Service Life Enhancement Program (SLEP) satellite. Together these assets will provide wideband services during the transition period between today's systems and the advent of the Objective X/Ka wideband system or Advanced Wideband System (AWS), which has merged with Transformational Communications System (TCS), in 2008-2009. The DSCS system will be replaced by five fully operational WGS satellites, each of which will be able to downlink 2.4 Gbit/s of data to tactical users. The very first WGS satellite in orbit will provide greater capability and bandwidth than all the DSCS satellites combined.^[4]

Diagram illustrating the payload subsystem of a WGS satellite

[edit] Space segment

The primary contractor for the satellites is Boeing Satellite Systems, which will build them around the Boeing 702 satellite platform. Originally five satellites were planned. On October 3, 2007 the Australian Defence Ministry announced Australia would fund a sixth satellite in the constellation.^[5] Once in their orbits at an altitude of 22,300 miles, each will weigh approximately 7,600 lb. The program intends to use both the Delta IV and the Atlas V as launch vehicles. The Air Force Space Command estimates each satellite will cost approximately $300 million.

The first launch was conducted by United Launch Alliance (ULA), at 00:22 GMT on 11 October 2007. The satellite was carried by an Atlas V (421) lifting off from LC-41 at Cape Canaveral Air Force Station (CCAFS). The second launch, currently projected to take place in 2008, will also be conducted by a ULA Atlas V 421. A ULA Delta IV-9450, flying from LC-37B at CCAFS will launch the third spacecraft. Originally, the second spacecraft was to fly on the Delta, and the third on the Atlas, but they were switched for an undisclosed reason.

After launch, the WGS-1 satellite was given the US military designation "USA-195".

[edit] Terminal segment

The Terminal segment describes the "users" or "customers" of the communication services provided by the WGS. Users include, U.S. Army ground mobile terminals, U.S. Navy submarines and fleet weapons platforms, national command authorities for the nuclear forces, and various national security/allied national forces. Additionally the Air Force Satellite Control Network will also use the WGS in a similar matter as the DSCS III constellation is used to route ATM packets through the DISA "cloud" to establish command and control streams with various satellite constellations.

[edit] Control segment

The Control segment refers to the satellite operators in charge of commanding and monitoring the satellite's bus and payload systems. Currently, as with the legacy DSCS constellation, bus commanding will be handled by the 3rd Space Operations Squadron out of Schriever AFB, Colorado. Payload commanding will be handled by the Army 53rd Signal Battalion headquarterd at Peterson AFB, Colorado.