The U.S. government provides GPS service free of charge and plans to invest more than $5.8 billion over the next 5 years in the GPS satellites and ground control segments. The Department of Defense (DOD) develops and operates GPS, and an interdepartmental committee—co-chaired by DOD and the Department of Transportation—manages the U.S. space-based positioning, navigation, and timing infrastructure, which includes GPS. DOD also provides most of the funding for GPS. The Air Force is responsible for GPS acquisition and is in the process of modernizing GPS to enhance its performance, accuracy, and integrity. The modernization effort includes GPS IIF and IIIA, two satellite acquisition programs that are to provide new space-based capabilities and replenish the satellite constellation; the ground control segment hardware and software; and user equipment for processing modernized GPS capabilities. Other countries are also developing their own independent global navigation satellite systems that could offer capabilities that are comparable, if not superior, to GPS. In recent years under the IIF program, the Air Force has struggled to successfully build GPS satellites within cost and schedule goals. It encountered significant technical problems that still threaten its delivery schedule and it struggled with a different contractor for the IIF program. These problems were compounded by an acquisition strategy that relaxed oversight and quality inspections as well as multiple contractor mergers and moves, and the addition of new requirements late in the development cycle. GPS was not the only space program started in the 1990s to face such challenges. In fact, DOD continues to face cost overruns in the billions of dollars, schedule delays adding up to years, and performance shortfalls stemming from programs that began in the 1990s and after that were poorly structured, managed and overseen. What sets GPS apart from those programs is that GPS had already been “done” before. The GPS IIF program was far less ambitious than efforts to advance missile warning and weather monitoring capabilities, for example. Our report documents the history of the IIF program and the decisions made early on that weakened the foundation for program execution. What is important to highlight today is that the program is still experiencing technical problems that still threaten its delivery schedule. For example, last year, during the first phase of thermal vacuum testing (a critical test to determine space-worthiness that subjects the satellite to space-like operating conditions), one transmitter used to send the navigation message to the users failed. The program suspended testing in August 2008 to allow time for the contractor to identify the causes of the problems and take corrective actions. The program also had difficulty maintaining the proper propellant fuel-line temperature; this, in addition to power failures on the satellite, delayed final integration testing. In addition, the satellite’s reaction wheels, used for pointing accuracy, were redesigned because on- orbit failures on similar reaction wheels were occurring on other satellite programs—this added about $10 million to the program’s cost. As a result of these problems, the cost to complete GPS IIF will be about $1.6 billion—about $870 million over the original cost estimate of $729 million. The launch of the first IIF satellite has been delayed until November 2009—almost 3 years late. The Air Force is taking measures to prevent the problems experienced on the GPS IIF program from recurring on the GPS IIIA program. Some of the measures the Air Force is taking include: using incremental or block development, where the program would follow an evolutionary path toward meeting needs rather than attempting to satisfy all needs in a single step; using military standards for satellite quality; conducting multiple design reviews, with the contractor being held to military standards and deliverables during each review; exercising more government oversight and interaction with the contractor and spending more time at the contractor’s site; using an improved risk management process, where the government is an integral part of the process; not allowing the program manager to adjust the GPS IIIA program scope to meet increased or accelerated technical specifications, system requirements, or system performance; and conducting an independent technology readiness assessment of the contractor design once the preliminary design review is complete. These efforts are not trivial. The primary causes of space acquisition problems in our view include (1) the tendency to start space programs too early, that is, before there has been assurance that the capabilities being pursuing can be achieved within resources and time constraints and (2) the tendency to attempt to achieve all requirements in one step rather than gradually. The GPS IIIA program was structured to avoid these problems and ensure the program has the right knowledge for moving forward into the acquisition process. Moreover, our work has cited prior acquisition strategies in which the lack of contractor oversight was a problem. Again, the actions being taken on GPS IIIA put controls in place to strengthen oversight and government involvement. We also recognize that the GPS IIIA program took steps to produce realistic cost estimates, which has generally not been done in the past. Nevertheless, there is still a high risk that the Air Force will not meet its schedule for GPS. First, it is aiming to deploy the GPS IIIA satellites 3 years faster than the IIF satellites. Second, the time period between the contract award and first launch for GPS IIIA is shorter than most other major space programs we have reviewed. Third, GPS IIIA is not simply a matter of replicating the IIF program. Though the contractor has had previous experience with GPS, it is likely that the knowledge base will need to be revitalized. The contractor is also being asked to develop a larger satellite bus to accommodate the future GPS increments and to increase the power of a new military signal by a factor of ten. In view of these and other schedule issues, we believe that there is little room in the schedule to accommodate difficulties that the contractor or program may face. Where does this leave the wide span of military, civil, and other user of GPS? If the Air Force does not meet its schedule goals for development of GPS IIIA satellites, there will be an increased likelihood that in 2010, as old satellites begin to fail, the overall GPS constellation will fall below the number of satellites required to provide the level of GPS service that the U.S. government is committing to providing. The performance standards for both (1) the standard positioning service provided to civil and commercial GPS users and (2) the precise positioning service provided to military GPS users commit the U.S. government to at least a 95 percent probability of maintaining a constellation of 24 operational GPS satellites. 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 percent. However, 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 replenished, and that the constellation will, in all likelihood, decrease in size. Based on the most recent satellite reliability and launch schedule data approved in March 2009, the estimated long-term probability of maintaining a constellation of at least 24 operational satellites falls below 95 percent during fiscal year 2010 and remains below 95 percent until the end of fiscal year 2014, at times falling to about 80 percent. See figure 1 for details. Such a gap in capability could have wide-ranging impacts on GPS users, though the exact impact is hard to precisely define, as it would depend on which satellites stop operating. To illustrate, however, the military could see a decrease in the accuracy of precision-guided munitions that rely on GPS to strike their targets. Disruptions in service could require military forces to either use larger munitions or to use more munitions on the same target to achieve the same level of success. Intercontinental commercial flights use predicted satellite geometry over their planned navigation route, and may have to delay, cancel, or reroute flights. Enhanced 911 services, which rely on GPS to precisely locate callers, could lose accuracy particularly when operating in urban canyons or mountainous terrain. The Air Force is aware that, over the next several years, there is some risk that the number of satellites in the GPS constellation could fall below its required 24 satellites, and that this risk would grow significantly if the development and launch of GPS IIIA satellites were delayed by several years. Consequently, Air Force Space Command has established an independent review team to examine the risks and consequences of a smaller constellation on military and civil users. There are measures the Air Force and others can take to plan for and minimize these impacts, which are detailed in our report. However, at this time Air Force representatives believe the best approach to mitigating the risk is to take all reasonable steps to ensure that the current schedule for GPS IIIA is maintained. Moreover, it is unclear whether the user community knows enough about the potential problem to do something about it. To maximize the benefit of GPS, the delivery of its ground control and user equipment capabilities must be synchronized with the delivery of the satellites so that the full spectrum of military assets and individual users can take advantage of new capabilities. This is a challenging endeavor for GPS as it involves installing GPS equipment on board a wide range of ships, aircraft, missiles, and other weapon systems. Our review found that because of funding shifts and diffuse leadership, the Air Force has not been successful in synchronizing satellite, ground control, and user equipment segments. As a result of the poor synchronization, new GPS capabilities may be delivered in space for years before military users can take advantage of them. The Air Force used funding set aside for the ground control and user equipment segment to resolve GPS satellite development problems, causing a delay in the delivery of new GPS capabilities. For example, in 2005 the Air Force began launching its GPS IIR-M satellites, which broadcast a second civil signal. Unfortunately, the ground control segment will not be able to make the second civil signal operational until late 2012 or 2013—7 years later.