DSB Task Force Wants More GPS 3 Satellites in Three Orbital Planes

A new report issued by an independent advisory committee recommends the U.S. Air Force take a new direction on its next-generation satellite navigation system, as various contractors throughout the space industry gear up to snare a role in the project.

The Defense Science Board Task Force, a federal advisory committee to the U.S. Department of Defense, completed a report Oct. 28 outlining its recommendations for the program. The report, called “The Future of the Global Positioning System,” was made available publicly Nov. 22.

The report recommends a constellation of 30 satellites make up the entirety of GPS 3 , stating that at least this many is necessary in order to create enough coverage to support ground operations. Currently, there are 28 satellites in orbit, with eight GPS 2R satellites and 19 GPS 2F satellites in the pipeline for the future, according to the report. With failures, the report states the constellation likely will fall closer to 24 satellites in the 2007-2012 time period, and that the Air Force only has committed to maintaining 24 satellites in the long term.

The task force believes the GPS 3 constellation should be deployed in three rather than six orbital planes, with 10 satellites per plane, which is how the European Space Agency’s Galileo system is being designed. According to the report, this will make it easier to sustain the overall constellation. In order to accomplish this, the report’s authors state that efforts must be made to shift to a three-plane constellation before any next-generation satellites are launched.

The task force recommended that as next-generation satellites are completed, two satellites be launched at a time on a medium-class launch vehicle to keep costs and weight down. It also argued that the secondary payloads envisioned for GPS 3 are not affordable in terms of cost and weight, and should be re-evaluated.

The request for proposal for the GPS 3 program is slated to be issued at either the close of this year or in early 2006. Lockheed Martin Corp., of Bethesda, Md., and Boeing Co., of Chicago, are the leading candidates to be the prime contractor for GPS-3 , as both have built prior generations of GPS satellites.

The first GPS 3 spacecraft is scheduled for launch in 2013.

GPS 3 is being designed with improved anti-jamming capabilities, but the task force believes those efforts may be insufficient to counter existing threats, particularly if the program is delayed any further.

“The risk in the GPS 3 program is real and its extended procurement schedule leaves an intolerable window for jamming vulnerability,” the report said.

The task force suggests adding anti-jam enhancements to individual military receivers to reduce risk in case the GPS 3 program does not proceed as scheduled.

With Galileo’s pending construction, the document recommends promoting civil interoperability with the European system.

With the award of the prime GPS 3 contract expected in the summer of 2006, other companies beyond Lockheed Martin and Boeing are gearing up for the project’s commencement.

Companies such as Harris Corp. of Melbourne, Fla., hope to play a role in the project’s development. According to Harris spokesman Brent Dietz, the company would like to contribute to the project in three ways. Harris is proposing to build ground-based hardware to be used for ground control, as well as a software system used for control, guidance and monitoring known as OS/Comet. Harris also hopes that its unfurlable antennae could be used aboard the satellites, Dietz said.

The ground component for GPS 3 is being broken down into a separate segment known as the GPS Operational Controls Segment (GPS OCS), which Waltham, Mass.-based Raytheon is pursuing, according to Bob Canty, director of the company’s Defense Systems unit .

Canty said the separation of the control segment has become a trend for Air Force business in the past two years.

“All of the new systems are pushing operations all the way out into the theatre, and as a result, how you use the system becomes very important,” Canty said.

Raytheon also is encouraged by an increased emphasis on the use of reprogrammable software to make GPS systems function, which gives the company a greater stake in the process.

“Clearly we see that trend as being a good thing for Raytheon,” Canty said.