The idea that GPS coverage will be pervasive all of the time in the future just might not pan out. That's because while some improvements in delivering components of the system have occurred, the US Air Force, which is responsible for the GPS system, faces numerous challenges in getting new satellite and support systems off the ground, according to a report out this week from the Government Accountability Office.
If that warning sounds familiar that's because the GAO warned of satellite problems in 2009, but says that some issues have gotten worse since then. And because GPS has become an essential element in military and many civilian operations, keeping it fully functional has become essential.
From the GAO: "Conditions have improved for the near-term size and availability of the GPS constellation. While Department of Defense has strengthened acquisition practices for GPS and made concerted efforts to maximize the life of GPS satellites, it still faces many of the same challenges we identified last year, as well as new ones we identified this year. For example, the GPS IIIA satellite program has complex and difficult work ahead as it undertakes assembly, integration, and test efforts, and its schedule may leave little margin to address challenges that may arise. Such issues could affect the Air Force's ability to launch satellites on time, which in turn may affect future GPS satellite constellation availability."
The GAO went on to say that continued delays with ground control systems and the challenges the Air Force is encountering with enabling quicker procurement of military GPS user equipment, new capabilities may not be delivered when the DOD needs them. For example, the contract for the newest ground system development effort, operational control segment-known as OCX-was awarded in February 2010, about 10 months later than the original contract award date. To account for the delay the Air Force extended the OCX delivery schedule by adding 16 months of development time. As a result, key OCX capabilities associated with the IIIA satellites will not be operational until September 2016 -over 2 years after the first IIIA satellite launch, the GAO stated.
The Air Force is working on a mitigation strategy that calls for development of a separate effort to launch and control the first IIIA satellite, the GAO stated. However, GPS Wing officials told the GAO such a system will not support new capabilities offered by IIIA, including a signal known as Military Code (M-code), which is designed to boost resistance to jamming, and three civil signals related to signal accuracy, aviation and international global space-based Position, Navigation and Timing systems, the GAO found.
Because there are currently 31 operational GPS satellites of various blocks, the near-term probability of maintaining a constellation of at least 24 operational satellites remains well above 95%. However, the DOD predicts that over the next several years many of the older satellites in the constellation will reach the end of their operational life faster than they will be replaced, and that the constellation will, in all likelihood, decrease in size, the GAO stated in 2009.
In the new report the GAO looked at what GPS meant to a number of key users of GPS systems. From the GAO report:
In the end of its report the GAO again called for the Secretary of Defense to appoint a single authority to oversee development of GPS space, ground control, and user equipment, to ensure they are synchronized, well executed, and potential disruptions are minimized.
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