A satellite constellation once regarded as an interim step to advanced military communications has become a mainstay in large part because of the technology it has borrowed from commercial users.

Already, the first Wideband Global Satcom (WGS) satellite, which has been in orbit over the Pacific Ocean for a year, is providing the same amount of high-bandwidth capacity as the entire Defense Satellite Communications System (DSCS) that WGS is beginning to replace. The new system pushes data transmissions of 2.5-3.3 gigabits per second - 10 times faster than DSCS.

The military's need for high bandwidth is ballooning. The requirements range from transmitting massive full-motion video intelligence files collected from UAVs in Iraq and Afghanistan to a growing dependency among high-ranking military leaders on video teleconferencing around the globe. Once called the Wideband Gapfiller Satellite program - envisioned as an interim capability between DSCS and the Advanced Extremely High-Frequency system that is to replace Milstar - WGS has graduated into a full-blown constellation of its own.

An initial order for three spacecraft was expanded in 2006 to build two more in a Block 2 upgrade. When Australia wanted to be included in the network, it agreed last December to fund a sixth $300-million Block 2 satellite as a price of admission. The full contract is valued at $1.84 billion, including training, ground support and other services.

Boeing is preparing to ship the second of these 13,000-lb. spacecraft to Cape Canaveral Air Force Station in early January to meet customer requirements for launch on an Atlas V, probably in late February or early March. Boeing's Satellite Development Center in El Segundo has the third spacecraft under construction in anticipation of a launch next summer and expects the fourth to be lofted in early 2009.

The WGS network is used by all the military services and is based on Boeing's workhorse 702 commercial satellite. Boeing officials say it has features that allow operators to detect the presence of jamming or other interference so they can take countermeasures to preserve communications.

While WGS spacecraft offer greater protection against interference than a typical commercial transponder satellite, they do not offer the encrypted capabilities of the hardened Milstar satellites. Data encryption and decryption are handled by ground terminals, but WGS supports transmission of encrypted data.

The system has many applications. It provides essential communication services for combat commanders to tactical units, and it also handles routine message traffic such as service members' e-mail.

Besides supplanting the X-band communications now provided by DSCS, WGS will add the flexibility of Ka-band service. Each spacecraft's ability to route communications from any of those frequency spectrums to any other on board is a new capability for military users, notes WGS Program Director Mark A. Spiwak of Boeing Space & Intelligence Systems.

In the past, field units have been stymied when trying to communicate with others using different systems. WGS helps sort out those issues while boosting the entire system's capacity. "It gives us more ability to encrypt," says Col. James Wolf, Air Force Space Command's lead officer on communications satellites. "It gives us a lot better spectrum density where we can pack a lot more bits into a given region on the ground."