Mitigating Gaps in Weather Satellite Data
The United States relies on two complementary types of satellite systems for weather observations and forecasts: (1) polar-orbiting satellites that provide a global perspective every morning and afternoon and (2) geostationary satellites that maintain a fixed view of the United States. Both types of systems are critical to weather forecasters, climatologists, and the military to map and monitor changes in weather, climate, the oceans, and the environment. Federal agencies are currently planning and executing major satellite acquisition programs to replace existing polar and geostationary satellite systems that are nearing the end of their expected life spans. However, these programs have troubled legacies of cost increases, missed milestones, technical problems, and management challenges that have resulted in reduced functionality and slips to planned launch dates. As a result, the continuity of satellite data is at risk.
Officials from the Department of Commerces National Oceanic and Atmospheric Administration (NOAA) acknowledge that there is a substantial risk of a gap in polar satellite data in the afternoon orbit, between the time that the current polar satellite is expected to reach the end of its life and the time when the next satellite is expected to be in orbit and operational. This gap could span from 17 to 53 months or more, depending on how long the current satellite lasts and any delays in launching or operating the new one. There is also a risk of a gap in the early morning orbit if the Department of Defenses next satellites do not work as intended. According to civilian and military satellite experts, this is a possibility because the two remaining satellites have been in storage for over a decade and will be quite old by the time they are launched. Similarly, while federal agencies do not anticipate gaps in geostationary satellite observations, such a gap could occur if satellites currently in orbit do not last as long as anticipated or if the major satellite acquisition currently underway encounters schedule delays.
According to NOAA program officials, a satellite data gap would result in less accurate and timely weather forecasts and warnings of extreme events, such as hurricanes, storm surges and floods. Such degradation in forecasts and warnings would place lives, property, and our nations critical infrastructures in danger. Given the criticality of satellite data to weather forecasts, the likelihood of significant gaps and the potential impact of such gaps on the health and safety of the U.S. population and economy, GAO has concluded that the potential gap in weather satellite data is a high-risk area and added it to the High Risk List in 2013.
NOAA faces ongoing challenges in ensuring the continuity of satellite operations in both the polar-orbiting and geostationary environmental satellite programs.
- Polar-orbiting satellites. NOAA officials anticipate a gap in the afternoon orbit from 18 to 24 months between the time that the current polar satellite reaches the end of its lifespan and when the first satellite in its Joint Polar Satellite System (JPSS) program is ready for operational use. GAO identified other scenarios where the gap could last from 17 to 53 months. In addition, there is the possibility of satellite data gaps in the Department of Defenses early morning orbit. The final two Defense Meteorological Satellite Program satellites may not work as intended after they are launched because they were built in the late 1990s and will be quite old by the time they are launched. If the satellites do not perform as expected, a data gap in the early morning orbit could occur as early as 2014. Satellite data gaps in the morning or afternoon polar orbits would lead to less accurate and timely weather forecasting, and as a result, advanced warning of extreme eventssuch as hurricanes, storm surges, and floodswould be affected.
In June 2012, GAO reported that while NOAA officials communicated publicly and often about the risk of a polar satellite data gap, the agency had not established plans to mitigate the gap. At the time, NOAA officials stated that the agency would continue to use existing satellites as long as they provide data and that there were no viable alternatives to the JPSS program. However, GAOs report noted that a more comprehensive mitigation plan was essential since it is possible that other governmental, commercial, or foreign satellites could supplement the polar satellite data. Further, because it could take time to adapt ground systems to receive, process, and disseminate an alternative satellites data, GAO noted that any delays in establishing mitigation plans could leave the agency little time to leverage its alternatives. GAO recommended that NOAA establish mitigation plans for pending satellite gaps in the afternoon orbit as well as potential gaps in the early morning orbit.
In September 2012, the Under Secretary of Commerce for Oceans and Atmosphere reported that NOAA had several actions under way to address polar satellite data gaps, including (1) an investigation on how to maximize the life of the current operational satellite, (2) an investigation on how to accelerate the development of the second JPSS satellite, and (3) the development of a mitigation plan to address potential data gaps until the first JPSS satellite becomes operational. The Under Secretary also directed NOAAs Assistant Secretary to conduct an enterprise-wide examination of contingency options and to develop a written, descriptive, end-to-end plan that considers the entire flow of data from possible alternative sensors through data assimilation and on to forecast model performance.
NOAA subsequently issued a mitigation plan for a potential gap in the afternoon orbit, between the current polar satellite and the first JPSS satellite. The plan identifies and prioritizes options for obtaining critical observations, including alternative satellite data sources and improvements to data assimilation in models. It also lists technical, programmatic, and management steps needed to implement these options.
However, it is not clear when decisions will be made to implement the steps needed to ensure that the options are viable. Moreover, it is not yet clear how this mitigation plan will be integrated with the Under Secretarys directive to begin developing an overarching end-to-end plan for sustaining weather forecasts. GAO has ongoing work assessing NOAAs efforts to limit and mitigate potential polar satellite data gaps.
- Geostationary satellites. While NOAAs policy is to have two operational geostationary satellites and one backup satellite in orbit at all times, continued delays in the launch of the first satellite in the Geostationary Operational Environmental Satellite-R (GOES-R) series could lead to a gap in satellite coverage. NOAAs policy proved useful in December 2008 and again in September 2012, when NOAA experienced problems with one of its operational satellites, but was able to move its backup satellite into place until the problems were resolved. However, beginning in April 2015, NOAA expects to have two operational satellites in orbit, but it will not have a backup satellite until GOES-R is launched and completes an estimated 6-month post-launch test period.
As a result, there could be a year or more gap during which time a backup satellite would not be available. If NOAA were to experience a problem with either of its operational satellites before GOES-R is in orbit and operational, it would need to rely on older satellites that are beyond their expected operational lives and may not be fully functional. Any further delays in the launch of the first satellite in the GOES-R program would likely increase the risk of a gap in satellite coverage.
In September 2010, GAO reported that NOAA had not established adequate continuity plans for its geostationary satellites. Specifically, in the event of a satellite failure, with no backup available, NOAA planned to reduce its operations to a single satellite and if available, rely on a satellite from a foreign nation. However, the agency did not have plans that included processes, procedures, and resources needed to transition to a single or foreign satellite. Without such plans, there would be an increased risk that users would lose access to critical data. GAO recommended that NOAA develop and document continuity plans for the operation of geostationary satellites that included implementation procedures, resources, staff roles, and timetables needed to transition to a single satellite, a foreign satellite, or other solution.
One year later, in September 2011, NOAA developed an initial continuity plan that generally includes these elements. Specifically, NOAAs plan identifies steps it would take in transitioning to a single or foreign satellite, the amount of time this transition would take, roles of product area leads, and resources such as imaging product schedules, disk imagery frequency, and staff to execute the changes. In December 2012, NOAA issued an updated plan that provides additional contingency scenarios.
However, it is not evident that critical steps have been implemented, including simulating continuity situations and working with the user community to account for differences in products under different continuity scenarios. GAO has ongoing work assessing NOAAs actions to ensure that its plans are viable and that continuity procedures are in place and have been tested.
In response to GAO recommendations to establish contingency and continuity plans, NOAA has established plans to address potential gaps in satellite data for both its polar-orbiting and geostationary satellite systems. However, these plans are only the beginning. NOAA must make difficult decisions on which technical, programmatic, and management steps it will implement to ensure that its mitigation plans are viable when needed. For example, for the polar-orbiting satellites, NOAA must make decisions about (1) whether and how to extend support for legacy satellite systems so that their data might be available if needed, (2) how much time and resources to invest in improving satellite models so that they assimilate data from alternative sources, (3) whether to pursue international agreements for access to additional satellite systems and how best to resolve any security issues with the foreign data, (4) when and how to test the value and integration of alternative data sources, and (5) how these preliminary mitigation plans will be integrated with the agencys broader end-to-end plans for sustaining weather forecasting capabilities. NOAA must also identify time frames for when these decisions will be made.
For the geostationary satellites, NOAA must demonstrate its progress in conducting training and simulations for contingency scenarios, evaluating the status of viable foreign satellites, and working with the user community to account for differences in product coverage under contingency scenarios. These steps are critical for NOAA to move forward in documenting the processes it will take to implement its contingency plans. Once these activities are completed, NOAA should also update its contingency plan to provide more details on its contingency scenarios, associated time frames, and any preventative actions it is taking to minimize the possibility of a gap.
GAO has ongoing work assessing NOAAs actions on both its polar-orbiting and geostationary satellite programs to determine whether its plans are viable and its continuity procedures are in place and have been tested.