GPS Vulnerability – A Surveyor’s Concern

For some time now, the US Military has been expressing some concern about the vulnerability of the GPS constellation.  GPS was initially developed for military purposes, and today remains its most important use.

The Department of Defense have pointed out that the economics and technologies to develop and field a credible threat to GPS are within the grasp of virtually any nation.  China has just recently demonstrated that they can destroy an orbiting satellite. Although, the satellites in the GPS constellation is in much higher orbits than the satellite China destroyed, the ability was demonstrated, and the threat should be considered real.

Further, replacement of destroyed satellites is not easily accomplished, because the debris from the destroyed satellites orbiting as hundreds or thousands of pieces of shrapnel, creates a band where new satellite could not coexist.

Parties other than the military and surveying community would be likewise affected. In fact, the number and scope of uses for GPS are almost limitless, from navigation to time synchronization, GPS magazine lists some of the agencies sharing our concern:

….air navigation and air traffic control (Federal Aviation Administration, commercial airline industry, and general aviation), inland waterway navigation (United States Coast Guard [USCG] and commercial fishing/transportation fleets), commercial vehicle tracking (interstate trucking industry and all those who use them), cell phone networks (associated service providers), and emergency response (911) networks (public safety organizations). This is not an all-inclusive list, and the dependencies are growing.

The secondary concern of us as surveyors should be: Are we maintaining the skills and tools necessary to preform our surveying duties in the case of a disruption or possible destruction of the GPS constellation? Or are we so dependent on GPS that our business would be jeopardized in the case of such an event?

For example, recent changes in the ALTA specifications relating to relative positional accuracy, almost certainly require GPS  in order to insure compliance.  Standards issued by state and local agencies have followed suit. 

As always, your comments are welcomed.