Global Positioning System: A Comprehensive Assessment of Potential Options and Related Costs is Needed
Highlights
What GAO Found
GAO found the Air Force, the military branch responsible for Global Positioning System (GPS) acquisition, in its report on Lower Cost Solutions for Providing Global Positioning System Capability, broadly addressed all four congressional requirements--system capability, implementation approaches, technical and programmatic risks, and estimated costs--for each option presented for the space segment. GPS consists of three segments--space, ground control, and user equipment--but the study only addressed the space segment, which accounts for the largest share of total GPS costs--more than half--in the Air Force's current budget. The Air Force identified and assessed nine options for future GPS space segments, ranging in cost from $13 billion to $25 billion from fiscal year 2013 through 2030. The report assessed each option based on a constellation or collection of 30 total satellites instead of 24, which is the Air Force's baseline GPS requirement for accuracy. This increase in total satellites raises an issue with the constellation size the Air Force intends to support in the future. Air Force officials stated that the cost analyses supporting the nine options were high-level cost estimates. Although this may be expected given the time constraints and other limitations of the study, these estimates are not at a level that would support future GPS investment decisions.
Although the Air Force report is a good starting point, more information on key cost drivers and cost estimates, and broader input from stakeholders would help guide future investment decisions. Specifically, the key cost drivers include dual launch capability (launching two satellites on a single launch vehicle), navigation satellites (smaller GPS-type satellites yet to be developed), and a nuclear detection capability. The cost estimates also excluded the ground control and user equipment segments and cost risk. Further, the Air Force did not obtain inputs from some key stakeholders such as those from the GPS positioning, navigation, and timing advisory community. Consequently, without conducting a more comprehensive assessment that addresses each of these concerns, the Air Force is not yet in a position to make sound future GPS investments.
Why GAO Did This Study
The GPS--a space-based satellite system that provides positioning, navigation, and timing data to users worldwide--has become an essential U.S. national security asset and component in daily life. The GPS program is being modernized to enhance its performance, accuracy and integrity. In 2013, the House Armed Services Committee directed the Air Force to report on lower-cost GPS solutions. The committee also mandated that GAO review the Air Force report. GAO (1) assessed the extent to which the Air Force GPS report met Committee requirements; and, (2) identified additional information that is important in guiding future GPS investments. GAO reviewed the Air Force report, interviewed officials responsible for preparing it, and consulted subject matter experts from the positioning, navigation, and timing advisory community.
Recommendations
GAO recommends the Air Force: (1) affirm the future size of the GPS constellation it plans to support; (2) ensure future assessments are comprehensive and include cost risk and the impact of options on all three GPS segments; and (3) engage the broader stakeholder community in future assessments of options. DOD concurred with these recommendations.
Recommendations for Executive Action
| Agency Affected | Recommendation | Status |
|---|---|---|
| Department of Defense | To better position the Department of Defense (DOD) as it continues pursuing more affordable GPS options, and to have the information necessary to make decisions on how best to improve the GPS constellation, the Secretary of Defense should direct the Secretary of the Air Force to affirm the future GPS constellation size that the Air Force plans to support, given the differences in the derived requirement of the 24-satellite constellation and the 30-satellite constellations called for in each of the space segment options in the Air Force's report. |
In providing comments on this report, the agency concurred with this recommendation, noting that the numbers of satellites required are affirmed annually in the President's Budget request. However, DOD continues to support a 30-satellite constellation, as established in each of the options its GPS study considered. Since the time of the report, DOD has not taken any action to reassess their approach to support a 24 or 30 GPS satellite constellation. Therefore, in August 2018, we are closing the recommendation.
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| Department of Defense | To better position the DOD as it continues pursuing more affordable GPS options, and to have the information necessary to make decisions on how best to improve the GPS constellation, the Secretary of Defense should direct the Secretary of the Air Force to ensure that future assessments of options include full consideration of the space, ground control, and user equipment segments, and are comprehensive with regard to their assessment of costs, technical and programmatic risks, and schedule. |
In providing comments on this report, the agency concurred with this recommendation, noting that, while consideration of the space and ground control segments should be comprehensive in these areas, the user equipment segment should be included in future assessments when those assessments include the fielding of new user equipment capability. Since the time of our report, DOD has not conducted a comprehensive assessment of future GPS options that includes all segments. Until they do, we cannot determine if they will include full consideration of the space, ground control, and user equipment segments, and are comprehensive with regard to their assessment of costs, technical and programmatic risks, and schedule.
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| Department of Defense | To better position the DOD as it continues pursuing more affordable GPS options, and to have the information necessary to make decisions on how best to improve the GPS constellation, the Secretary of Defense should direct the Secretary of the Air Force to engage stakeholders from the broader civilian community identified in positioning, navigation, and timing (PNT) policy in future assessments of options. This input should include civilian GPS signals, signal quality and integrity, which signals should be included or excluded from options, as well as issues pertaining to other technical and programmatic matters. |
In providing comments on this report, the agency concurred with this recommendation, noting that stakeholders from the broader civilian community identified in PNT policy should be engaged in future assessment of options that include changes to the Standard Positioning System performance standard or to agreements or commitments the DOD has already made with civil stakeholders. Until DOD conducts future assessments of options for GPS constellations, we cannot determine if they will include the views of stakeholders from the broader civilian GPS user community with respect to civilian GPS signals, signal quality and integrity, and other technical and programmatic matters.
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