While engaging the enemy, there is a need for the warfighters on the ground to see in realtime exactly what the UAV or satellite above is seeing.

The DOD Transformational Satellite Communications System (TSAT) is conceived as a constellation of satellites that provide a space based high bandwidth communication backbone to allow field units to access optical and radar imagery from UAV and satellites in real time. The constellation will support Communications on the Move (COTM) to as small as 1 ft terminals and provide a dynamic adaptation of data rates in response to jamming or weather conditions.

A visual image from a UAV that would take 2 minutes to process with the Milstar II satellite system would take less than a second with TSAT. A radar image from a Global Hawk UAV (12 minutes), or a multi-gigabyte radar image from space-based radar (88 minutes), would also take less than a second with the TSAT network. Best of all, the recipient can be on the move with a relatively small receiver, anywhere in the world.

TSAT constellation satellites will be placed in Geostationary Earth Orbit (GEO). In order to provide very high bandwidths TSAT will use laser for satellite to satellites (Space Backbone) communication and possibly for communication between satellites to airborne assets like AWACS, JSTARS and Global Hawks (Airborne Network). The Space and Airborne Network Layer will support data rates of 2.5 gigabits to 10 gigabits per second. However, only 20 to 50 or so of these links would be available and these will most likely be dedicated to major intelligence, surveillance and reconnaissance assets in space and in the air.

Data from the Space and Airborne Network Layer will flow on about 8,000 simultaneous radio frequency (RF) data links, which will provide connectivity to strategic assets and tactical users as well as the aerial intelligence, surveillance and reconnaissance (ISR) platforms. The RF segment of TSAT will support data rates up to 45 Mbps

Six satellites are scheduled for launch starting in 2011 with five of them to be operational satellites and the sixth intended for attrition purposes. Lockheed-Martin and Boeing are competing for this program with a prime contractor selected in 2006.

The Broader Picture

The DOD TSAT is part of Transformational Communications Architecture (TCA) and is part of the vision for a Global Information Grid (GIG).

There are currently three organization that are independently developing satellite based high speed data networks.

• NASA
• Department of Defense (DOD)
• Intelligence Community (IC)

Each of above three organizations launches and manages its own satellite constellation.

The Global Information Grid (GIG) is an endeavor to make the three independent networks above communicate with each other. It is a system of systems that can adapt to user requirements and to stresses imposed on the network. This adaptability also enables the infrastructure to scale as necessary to support force structure(s) of arbitrary size, or to incorporate new processing, network and communications.