GPS is a global positioning, navigation, and timing system consisting of space, ground control, and user equipment segments that support the broadcasts of military and civil GPS signals. These signals each include positioning and timing information, which enables users with appropriately-equipped GPS receivers to determine their position, velocity, and time, 24 hours a day, in all weather, worldwide. GPS is used by all branches of the military to guide troop movements, assist with logistics support and situational awareness, and synchronize communications networks. In addition, weapon systems, including munitions, are guided to their targets by GPS signals, and GPS is used to locate military personnel in distress. Early in the development of GPS, its scope was expanded to include complementary civil capabilities such as civil, maritime, and land navigation. Space, ground control, and user equipment segments are needed to take full advantage of GPS capabilities. The GPS space segment consists of a constellation of satellites that broadcast encrypted military signals and civil signals. In recent years, because numerous satellites have lasted longer than anticipated, the constellation has grown well beyond the minimum requirement of 24 satellites to approximately 40 satellites of various generations, with 8 in residual status. The satellites are operated by a master control station that regularly updates navigation signals on the satellites. Using these navigation signals, GPS military and civilian user equipment receivers determine a user’s location. Figure 1 below illustrates how GPS satellites, ground control, and user equipment function together as an operational system. The GPS ground control segment primarily consists of software deployed at a master control station at Schriever Air Force Base, Colorado, and at an alternate master control station at Vandenberg Air Force Base, California. The ground control software is supported by 6 Air Force and 11 National Geospatial-Intelligence Agency monitoring stations located around the globe along with four ground antennas with uplink capabilities. Information from the monitoring stations is processed at the Master Control Station to determine satellite clock and orbit status. The GPS user equipment segment includes military and civilian GPS receivers. These receivers determine a user’s position and time by calculating the distance from four or more satellites using the navigation signals on the satellites to determine its location. Military GPS receivers are designed to utilize the encrypted military GPS signals that are only available to authorized users, including military and allied forces and some authorized civil agencies. Civilian—including commercial— receivers use the civil GPS signal, which is publicly available worldwide. In 2000, DOD began an effort to modernize the space, ground control, and user equipment segments of GPS to enhance the system’s performance, accuracy, and integrity. To that end, the Air Force is now in the process of developing a new generation of GPS III satellites, OCX, and M-code capable MGUE receivers. GPS III satellites are planned to supplement and eventually replace the constellation of GPS satellites now in orbit; these satellites consist of multiple versions or generations developed and launched over the years. The first GPS III satellite was originally expected to be available for launch in April 2014; however, due to development problems it is now expected to be ready for launch in May 2017. A complete GPS III satellite has not yet been tested, and the program is now rebaselining its cost estimates as a result of the schedule delay and associated increased costs. The GPS ground control segment is being modernized under the OCX program. OCX is required because the existing GPS control system, Operational Control System (OCS) cannot control—and therefore enable—the modernized features of the two latest generations of GPS satellites—IIR-M and IIF—currently in orbit. The Air Force plans to develop OCX in blocks, with each block delivering upgrades as they become available. Block 0 is intended to support the launch and initial testing of GPS III satellites; block 1 is designed to command and control the GPS II and III satellites and basic modernized signals; and block 2 is to enable the full modernized M-code signal and support, monitor, and control additional navigation signals. OCX block 1 is needed to incorporate GPS III satellites into the operational constellation to sustain required levels of GPS signal coverage, because the legacy OCS system cannot support the GPS III satellites. OCX is also required to enable military and civil use of modernized GPS signals. In particular, the military cannot use M-code signals for enhanced warfighting until OCX block 1 is delivered. The Air Force began the OCX program in 2007 with a technology development phase, referred to as phase A. The Air Force awarded phase A contracts, for approximately $160 million each, to Northrop Grumman in Redondo Beach, California, and Raytheon Intelligence and Information Systems in Aurora, Colorado to produce competitive prototypes. Following the competitive down-select between these firms’ prototypes, the Air Force awarded the development contract to Raytheon in February 2010. This $886 million contract covered the development of OCX blocks 1 and 2 (as discussed in this report, block 0 was added as a contract modification later), with an option to begin preliminary work on blocks 3 and 4 which are to provide additional capabilities to support follow-on, upgraded versions of GPS III satellites. At the formal start of development (milestone B), the Air Force estimated the total OCX acquisition costs—including other costs such as expenditures on technology development prior to 2010 and annual management support and enterprise integrator services—at $3.5 billion. According to Air Force documentation, enterprise integrator services are required to ensure GPS enterprise coordination among the ground, space, and user equipment segments. These costs do not include funding contributions from civilian agencies to support OCX; according to Air Force documentation, the Department of Transportation and other agencies are to provide resources to DOD to develop and operate GPS civil capabilities. For the purpose of this report, OCX development costs refer to the costs of the development contract with Raytheon. Military GPS receivers are also being modernized under the MGUE program. The Air Force was directed by the Assistant Secretary of Defense for Networks and Information Integration in August 2006 to develop M-code capable GPS receiver cards to meet military services’ needs. In January 2011, the Ike Skelton National Defense Authorization Act for Fiscal Year 2011 directed that DOD not obligate or expend funds to procure GPS user equipment after fiscal year 2017 unless that equipment is capable of receiving M-code. Figure 2 below shows an illustration of a MGUE receiver card. The modernized receiver cards are to provide U.S. forces with enhanced position, navigation, and time capabilities, while improving resistance to existing and emerging threats, such as jamming. The Air Force plans to develop MGUE in two increments. The first increment, now under way and expected to cost about $1.7 billion, utilizes three prime contractors. All three contractors—L-3 Interstate Electronics Corporation, Raytheon Space and Airborne Systems, and Rockwell Collins—are developing receiver cards for ground environments. Raytheon and Rockwell Collins are also developing combined aviation/maritime receiver cards for use in air and sea environments. The Air Force plans to build on the work conducted in Increment 1 to develop a more compact receiver card in Increment 2 that can be used when size, weight, and power need to be minimized and that can serve as an “engine” for future military GPS receivers. At this time, the Air Force is also exploring the possibility of using Increment 1 technologies to support munitions, handheld devices, and space applications that it previously anticipated supporting with Increment 2. The Air Force initially began development of M-code in fiscal year 2003. It then transitioned that work to the modernized user equipment (MUE) program in 2006. According to GPS program updates, MUE was troubled by issues such as underestimation of software complexity, longer than anticipated software development time, and more difficult than expected software and hardware integration. These issues, among others, resulted in significant cost and schedule growth. The MUE program yielded aviation and ground prototypes of M-code-capable components, cost about $498 million, and spanned about 7 years, ending in 2013. Concurrent with and based on MUE development work, the Air Force initiated the MGUE program in 2011. While DOD policy on GPS user equipment and procurement in 2006 indicated the Air Force was to develop MGUE to production-ready status, the Air Force currently plans to develop MGUE Increment 1 ground and aviation/maritime receiver cards to the point of production representative test articles. It then intends for the MGUE program office to provide funding to the military services so that they can acquire, integrate, and operationally test the receiver cards on service-specific “lead platforms.” These platforms are expected to serve as pathfinders for the military services’ ground, aviation, and maritime environments and are currently designated by the services as follows: Army–Defense Advanced GPS Receiver (DAGR) Distributed Device (D3) onboard a Stryker ground combat vehicle; Air Force–B-2 Spirit aircraft; Navy–DDG-51 Arleigh Burke Destroyer hosted by GPS-based Positioning, Navigation, and Timing Service (GPNTS); and Marine Corps–Joint Light Tactical Vehicle (JLTV). Once operational testing is complete, the military services will then be responsible for procuring MGUE Increment 1 for their weapons systems. DOD indicates that the military services anticipate procurement of about 207,000 MGUE Increment 1 receiver cards. Historically, full fielding of user equipment has lagged behind the anticipated availability of GPS satellite and ground systems. For example, in 2009 we reported that the Air Force expected GPS satellite and ground systems to be available in 2013 to transmit and process the M-code signal, but that fielding of M- code equipment to all designated military users would not be complete until 2025.