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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report C Abstracts Prepared by Workshop Panelists IMPACTS OF SPACE WEATHER ON SATELLITE OPERATORS AND THEIR CUSTOMERS Michael Bodeau, Technical Fellow, Northrop Grumman Corporation Satellites provide a wealth of services to mankind: Satellites (e.g., GOES, POES, DMSP) provide continuous monitoring of terrestrial weather and allow governments to warn citizens of adverse conditions such as hurricanes. Hundreds of communication satellites cost-effectively connect remote populations to news, education, and entertainment (e.g., global cell phones). Communication satellites also provide one of the most cost-effective means for interconnecting businesses (one-to-many and many-to-one networks) and customers. Satellites provide a critical backup to terrestrial cable systems critical to restoring services during catastrophic events (earthquakes, hurricanes) that damage the ground-based systems. Precision location made possible by GPS satellites is now becoming a ubiquitous feature embedded in many commercial products (automobile navigations systems, cell phones, dog collars). Science satellites study the universe (e.g., Hubble, Chandra, and other astronomy satellites) and our planet (e.g., NASA’s Aura and Aqua). Since the beginning of the space age in the 1960s and the commercialization of space in the 1970s, space weather has posed a constant challenge to designers and operators of satellites, and indirectly to their customers. The impacts of space weather have ranged from momentary interruptions of service to a total loss of capabilities when a satellite fails. This presentation reviews the impact of one space weather “storm” on a pair of communication satellites to show the dramatic impact to the satellite operator and its customers when space weather interrupts services. Some of the direct costs of the satellite anomalies are reported, while the more far-reaching impacts on society as a whole are discussed.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report SPACE SYSTEMS USER PERSPECTIVE ON SPACE WEATHER DATA PRODUCTS David Chenette, Lockheed Martin Space Systems Company Advanced Technology Center Lockheed Martin and its customers rely on high-quality space weather data products from the NOAA/NWS Space Weather Prediction Center to help manage the risks of a variety of critical, high-value activities. These include go/no-go criteria in launches, planning of on-orbit operations (including radiation protection), and support of post-anomaly investigations, which are essential to our product improvement process. Our customers accept launch delays due to poor terrestrial weather, so launch vehicles need not be designed to operate reliably through tornados or hurricanes, for example. Similarly, significant cost efficiencies are realized by not designing launch vehicles for assured performance in unusually hazardous space weather conditions. Managing the risk of the resultant vulnerability requires that launch decisions take into account the space weather conditions expected during the launch and early on-orbit operations. Because the Sun is a significant and impulsive source of high-energy radiation that can disrupt electronics, near-real-time measurements and accurate short-term predictions of solar activity are essential to maintaining the high reliability of launch systems. Predictions of an hour to several hours in advance are required, depending on the mission. Beyond the initial launch, other on-orbit operations may be susceptible to unusual or extreme space weather conditions. For example, some communications satellites at geosynchronous orbit are more sensitive to the effects of spacecraft charging during orbit maintenance operations than during normal operations. Planning these operations to avoid this susceptibility requires predicting the level of geomagnetic activity from several days to a week in advance. Real-time monitors of geomagnetic activity and predictions for up to a day in advance are required during the actual operations. Forecasts and knowledge of high-energy solar activity also are critical to radiation safety in manned space operations. The amount of radiation shielding provided by a space suit during extravehicular activity, for example, is significantly less than the maximum shielding that can be provided by a spacecraft. Systems in low Earth orbit are shielded from high-energy solar radiation by Earth and its magnetic field, but for high-inclination orbits, depending on the longitude of the orbit ascending node, Earth’s magnetic shielding is not effective, and systems and people can be exposed to radiation at dose rates that are thousands of times higher than average. Also, the shielding effect of Earth’s magnetic field does not extend to the Moon; and for flights to Mars humans could be susceptible to solar events on the far side of the Sun, which are not visible from Earth. Accurate predictions of major solar events are required to protect man and space systems against the radiation risks posed by major solar flare events. Today we can identify active regions that are likely to produce large solar particle events, and we can classify events and predict expected radiation levels after they occur, but we do not have sufficient data and understanding to predict the timing of these events. Improvements are required both in understanding the precursors to major solar events and in the type and resolution of the data necessary to reveal the signatures of those precursors. Finally, Lockheed Martin depends on comprehensive space weather data products to support post-anomaly investigations. Detailed data are required to describe the space weather conditions at the time and location of any anomaly to assess whether or not the anomaly was related to those conditions. In cases where a causal relationship can be identified, the results are used to improve the design, to modify the implementation of the design, or to modify operations to protect against future occurrences. Comments on Data and Predictions The data now provided from the combination of POES and GOES space weather sensors provide excellent real-time monitors of space weather conditions at low Earth orbit and at geosynchronous orbit, and together they can be used to estimate conditions at intermediate altitudes. These data also monitor solar energetic particle radiation intensity near Earth and the extent to which this radiation penetrates into the magnetosphere. They do not support predictions of space weather events, beyond extrapolations that can describe the evolution of a space weather event after it has occurred. Real predictions depend on measurements of the Sun and the solar wind. The state of the art of these predic-
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report tions has improved significantly over the past few years, but in many cases it is only slightly better than a prediction based on persistence. Both the level of detail in our understanding of conditions at the Sun and the fidelity of our models for transport from the Sun to Earth contribute to the current deficiencies. The increases in data quality and resolution that are being and will be provided by the GOES Solar X-ray Imagers, the NASA STEREO mission, the Japanese Hinode Solar Optical Telescope, and soon by NASA’s Solar Dynamics Observatory promise major improvements in our understanding of conditions at the Sun. One way to reduce the deficiencies due to the transport models is to measure solar wind conditions upstream of Earth. The ACE spacecraft has provided such measurements, including limited data in real time, and has demonstrated their value. It is essential to “near-real-time” predictions (taking advantage of the tens of minutes of advance warning possible from L1) that these measurements be continued, and augmented with multipoint observations to enable corrections for geometrical effects. THE 1859 GEOMAGNETIC SUPERSTORM James L. Green, NASA The great geomagnetic storm of 1859 is really composed of two closely spaced massive worldwide auroral events. The first event began on August 28 and the second began on September 2. It is the storm on September 2nd that resulted from a white-light flare, observed by Carrington and Hodgson, that occurred on the Sun on September 1. Although still not widely believed at the time, the flare and storm observations showed that the Sun and aurora were connected and that auroras do generate strong ionospheric currents. Since the weather was mostly clear over many of the inhabited areas of Earth, over the several days of the storm an enormous number of people observed the aurora. In addition to published scientific measurements, newspapers, ship logs, and other records of that era provide an untapped wealth of firsthand observations giving time and location along with reports of the auroral forms and colors. At its height, the aurora was described as being a blood or deep crimson red that was so bright that one “could read a newspaper by it.” Several important aspects of this great geomagnetic storm are simply phenomenal. Significant portions of the world’s 200,000 km of telegraph lines were adversely affected. Many of them were unusable for 8 hours or more, and there was a small but notable economic impact. At its peak, the Type A red aurora lasted for several hours and was observed to reach extremely low geomagnetic latitudes on August 28-29 (25 degrees) and on September 2-3 (18 degrees). Auroral forms of all types and colors were observed below 50 degrees latitude for about 24 hours on August 28-29 and about 42 hours on September 2-3. Kenneth McCracken at the University of Adelaide discovered among the ice core data from Greenland and Antarctica that the 1859 nitrate anomaly, generated by the storms accompanying solar particle events (SPEs), stands out as the most extreme event during the last 500 years, with an intensity roughly equivalent to the sum of all the major SPEs during the last 40 years. According to Brian Thomas at Washburn University, the 1859 superstorm was strong enough to actually reduce atmospheric ozone by 5 percent for up to 4 years afterward. From a large database of ground-based observations the extent of the aurora in corrected geomagnetic coordinates can be determined over the duration of the event. Based on modern understanding of how aurora and ionospheric and magnetospheric currents reflect the rearrangement of the magnetosphere in response to changes in the solar wind, the extreme nature of this event can be better understood. It is most likely that these two major auroral storms are from two closely spaced interplanetary coronal mass ejections (ICMEs) reaching Earth very close together in time. The interaction of a fast ICME plowing through a slower ICME has been observed and produces a much stronger shock. This effect may be partially responsible for the extreme nature of the September 2-3 auroral event. If these ICMEs did not interact, it is clear that the August 28-29 event must have cleared a path in the solar wind, thus allowing the September 2nd CME to transit to Earth in 17.5 hours rather then the average ICME transit time of about 80 hours. It is clear that we have not experienced space weather anything like the 1859 superstorm event in the modern spacecraft era, which to date may have been unusually benign from an SPE perspective. We should be fully aware of what the Sun is capable of producing as we increase our reliance on our space mission assets.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report SPACE WEATHER, A DOD PERSPECTIVE Kelly J. Hand, U.S. Air Force Space Command Successful military operations rely on our ability to effectively integrate weather information into the planning and execution of land, air, and sea operations, but do space weather and its effects matter to military operations? On the terrestrial weather side, practical examples of weather’s importance to the effectiveness of military operations are numerous. Successful air operations require knowledge of weather over the target and include plans for weather conditions on ingress and egress routes to and from the target. Land force operations would certainly be at risk without understanding the actual and forecast soil conditions and their impact on land force trafficability. Accurate observations and forecasts of sea-state and littoral conditions are required in order to safely and effectively conduct naval and marine operations. But does space weather matter to the effectiveness of space and terrestrial military operations? The answer is yes. The military’s need for space weather knowledge is linked directly to environmental conditions relevant to impacts on space and terrestrial technological systems and the services those systems are intended to provide. Ultimately, the military value of actual and predicted space weather information is dependent on our ability to apply it effectively. As with terrestrial weather, the benefits are realized when military system operators and users can proactively mitigate or plan for the effects on their specific system or service. In this regard our nation’s military relies on our national space weather information infrastructure in general and on the Air Force Weather Agency in particular. The capability of this infrastructure is to monitor, specify, and predict environmental conditions to serve a variety of national needs, including those relevant to military system and mission effects. We call this the space weather piece of space situational awareness (SSA). For effective space weather SSA it is important to realize that environmental conditions can significantly affect a military system’s performance and therefore may impact its ability to bring intended services to the warfighter. For example, satellite systems, spacecraft components and their payloads, communication links for satellite command and control and mission data, and the satellite’s respective ground sites can all be affected by the environmental conditions in which they operate. Likewise, terrestrial systems like high-frequency (HF) communications, surveillance, or missile-tracking radars that contribute to missile warning missions can also be affected by the environment. Thus the degree to which the environment impacts these systems and information can be applied to improve performance or protect these systems defines the type of space weather information needed. Fortunately, the natural space environment information the military is concerned about is very similar to information of interest to scientists, NASA operations, and the civil and commercial sectors. This environment of common interest includes the Sun and its energy and mass emissions, interplanetary space and what it contains, and the near-Earth space environment, including the physical parameters that define the magnetosphere, thermosphere, and ionosphere. To illustrate how the military applies this information, a few military satellite systems are described as practical examples. Figure C.1 is a screen capture of a display of the near-Earth space environment generated by an Air Force Research Laboratory software program. It illustrates the complexity of the natural space environment in the context of low Earth orbit (LEO), medium Earth orbit (MEO), geosynchronous orbit (GEO), and highly elliptical orbit (HEO) satellites. Figure C.1 shows, high above Earth, a cross section of the inner Van Allen belt (~1500-8000 miles altitude—just outside most LEO satellite orbits) and outer radiation belts (MEO intersects the most intense portion at ~12,000 miles altitude). LEO satellites such as those in the Defense Meteorological Satellites Program (DMSP) operate through the upper atmosphere (at about 600 miles) and are affected by atmospheric drag and sometimes trapped and solar particle radiation. MEO satellites such as the Global Positioning System (GPS) satellites operate in the Van Allen radiation belts at about 12,000 miles altitude and are subject to constant bombardment by the highly energetic electrons that populate this region as well as energetic solar protons and high-energy electrons. Geostationary satellites, like the Defense Satellite Communication System (DSCS) satellites, are at the outside of the radiation belts but operate in a region where charging and discharging can occur on the surface of the spacecraft. Also, GEO satellites experience effects from highly energetic cosmic and solar radiation not as prevalent at LEO altitudes. For these satellite system examples, the users of natural space environmental information include satellite operators and engineers. An example of applications of space weather data includes enabling quicker resolution of
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report FIGURE C.1 Display of the near-Earth space environment generated by an Air Force Research Laboratory software program. spacecraft anomaly investigations to get the satellite back into operations and reduce downtime. Also, prediction of when conditions will occur and how bad they will be in the future at the particular satellite can be incorporated into scheduled maintenance procedures. Finally, all satellites and some ground-based space systems must propagate their radio signals through the ionosphere to reach terrestrial users. Depending on the frequency of the radio signal, the ionosphere can significantly degrade the performance of space system and services, such as communication and GPS services. An example of a terrestrial military system impact concerns high-frequency long-haul communications. An energetic solar x-ray burst can completely black out this type of communication system across the entire Sun-lit Earth. With sufficient space weather awareness, users can plan for and work around these impacts. These few examples highlight the importance of accurate knowledge of the current and predicted state of the natural space environment on military operations. Conclusion Space weather has impacts on both terrestrial and space technological systems and services used by the military. Thus the military will continue to depend on our nation’s space weather support infrastructure to provide current knowledge and predictions of the natural space environment. In the future as the nation’s dependence on space evolves, its reliance on space weather support infrastructure will increase and will benefit from improvements in the state-of-the-science and transition of that science to improved operations.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report CURRENT SPACE WEATHER SERVICES INFRASTRUCTURE IN EUROPE Michael A. Hapgood, CCLRC Rutherford Appleton Laboratory Chair, ESA Space Weather Working Team The past 10 years have seen huge progress in developing space weather as a discipline in Europe. In particular there is now a well-established European space weather community comprising scientists and engineers who work together to advance the discipline. However, this bottom-up unity is not yet reflected at higher levels. Space weather services in Europe are set in a complicated, indeed fragmented, landscape that contains a mix of national and European activities. At a European level space weather activities are supported by a number of actors. The most prominent, of course, is the European Space Agency (ESA). The ESA has done much to stimulate space weather activities. In particular, it has provided seedcorn funding for programmatic studies and for a pilot project on space weather services. These have been very successful and have played a huge part in building the present European space weather community. The pilot project has established a network of 25+ space weather services (SWENET, Space Weather European Network). This network is ideally positioned to be the foundation of an operational European space weather infrastructure. However, to do that, it now needs to find an appropriate long-term home in the broader European landscape. ESA cannot be that home as its task is to carry out research and development—and, having developed new services, it needs to spin them out into an operational body (as it has previously done in building a space meteorology system for Europe—now EUMETSAT). The proposed European program on space situation awareness, which includes space weather as a major element, may provide a path toward that home, especially if, as planned, it builds by federating existing European services. The other prominent European actor is the European Union (EU). The EU is developing a deeper involvement in space activities; for example, the new EU constitutional treaty, when ratified, will give it a formal legal competence in matters of space policy. This is expected to reinforce its relationship with ESA (their memberships overlap but are not identical), with the EU providing overall policy direction while ESA leads the technical activities that implement those polices. But even without the treaty the EU has been supporting space activities, including some in the space weather domain. EU research funding has supported a variety of activities. Most important is probably the support of human networking under the so-called COST (Cooperation on Space and Technology) actions. There have been several COST actions on trans-ionospheric radio propagation (including space weather effects), and a COST action on space weather has just been completed successfully. A proposal for a new action on space weather is under review. The EU has also funded the development of a coordinated system for digital ionosonde measurements and their dissemination (the DIAS project); a proposal for a follow-up project to combine ionosonde and GPS total electron content measurements is under review as part of a February 2008 call for research infrastructure projects. The EU has also recently funded a major project (SOTERIA) to enable the better science exploitation of space weather data. The EU-funded COST action on space weather has produced a Space Weather Portal that has the potential to be a gateway to a range of European services. This is likely to be a major focus for future efforts by the European space weather community, especially if the new COST action is approved. These European projects all provide cross-national support that focuses on front-end services, e.g., generation and dissemination of data products. There has so far been limited European support for space weather monitoring activities that generate the data needed as input to services. (We assume a model where space weather services deliver data products that are of use to end users and those data products are outputs from models of the space weather environment driven by measurements of the environment upstream from the region of interest.) The provision of space weather monitoring is predominantly done by national bodies. A 2001 survey for ESA identified over 100 sensors—most ground-based and focused on measurements of the Sun, ionosphere, and ground-level effects (magnetic field and neutrons). European space-based measurements are limited but include (1) by-products from European space science instruments (e.g., the SWAP solar imager on Proba-2 and the Heliospheric Imager on STEREO), (2) ESA’s program to fly space radiation monitors on a wide range of missions, and (3) some limited space weather monitoring on EUMETSAT missions, e.g., the NOAA package on METOP. ESA is seeking to stimulate better coordination of measurements and data handling related to spacecraft effects through a networking
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report activity that taps into relevant expertise across Europe (Spacecraft Environment and Effects Network of Technical Competence, SEENoTC). In some cases current national provision puts the monitoring activities at some risk in terms of funding; the national agencies that fund space weather monitoring often have limited understanding of space weather and its European and global context. This is especially true if space weather is funded by agencies that are focused on fundamental science and lack appreciation of modern scientific thinking on complex natural environments. Space weather sits comfortably with environmental disciplines such as atmospheric physics. It sits less well with disciplines that are dominated by a reductionist approach to science. European coordination is an important tool for raising awareness of the importance of individual space weather measurements and allowing national decision makers to understand the global context into which measurements fit. There are emerging national space weather programmes in several countries—in particular Belgium, France, Germany, and Spain. Denmark and Norway have specialized interests through leadership roles in specific projects—for Denmark the ESA/SWARM mission to study Earth’s magnetic field with greater resolution and for Norway the exploitation of Svalbard as a super-observatory for space weather phenomena. Other countries with strong space weather interests include Finland, Italy, Poland, Portugal, Switzerland, Sweden, and the United Kingdom. Finally we present a SWOT analysis of the European scene. The strengths in respect of space weather services are their value as an application of existing skills in solar-terrestrial and space plasma physics and the ability of developers to engage the wider engineering community. The weaknesses are the fragmented programs discussed above, together with the limited awareness of space weather among decision makers, the poor quality of many existing products, and the risks that arise when space weather is seen as part of astronomy rather than the geosciences. The opportunities are the ability to set a global context in which to make a case for space weather services, and the way that human networking can help to build service context and fix the quality of products. The threats are the risk of piecemeal funding cuts at the national level, possibly exacerbated by competition with other areas. Space weather is also under threat when decision makers think of space as being empty and thus fail to appreciate the effects of the plasmas that pervade outer space. GLOBAL POSITIONING SYSTEM Christopher J. Hegarty, The MITRE Corporation The Global Positioning System (GPS) is a satellite navigation system operated by the United States that includes a constellation of nominally 24 satellites in medium Earth orbit with an approximate altitude of 20,000 km. As illustrated in Figure C.2, new civil and military signals are being introduced. These include the L2 civil (L2C) and military (M code) signals that began with the launch of the first Block IIR-M satellite in 2005. In 2009, the first Block IIF satellite will add a new civil signal, referred to as L5, at 1176.45 MHz. In 2014, the first Block IIIA satellite will add an additional civil signal, L1C, at 1575.42 MHz. Based upon current schedules, the GPS constellation will be fully populated by 2014, 2016, and 2021, respectively, with L2C-, L5-, and L1C-capable satellites. All of the new civil and military signals include advanced capabilities that are anticipated to result in a significant increase in robustness against space weather effects, specifically ionospheric scintillation and solar radio noise bursts. These capabilities include pilot components for more robust tracking (e.g., a reduction of the minimum signal-to-noise ratio necessary for tracking by ~3-5 dB) and forward error correction of the broadcast navigation data to enable demodulation in lower signal-to-noise conditions. Two of the new civil signals, L2C and L5, also provide modest increases (1.5 dB and 4.5 dB, respectively) in received signal power relative to C/A code. The addition of L2C and L5 furthermore allows civil GPS receivers to more robustly measure ionospheric delays as compared to the only current civil alternative to employ codeless or semi-codeless techniques to track the encrypted GPS P(Y) code signals on the GPS L2 frequency.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report FIGURE C.2 Evolution of GPS signals. THE VULNERABILITY OF THE U.S. ELECTRIC POWER GRID TO SEVERE SPACE WEATHER EVENTS, AND FUTURE OUTLOOK John G. Kappenman, Metatech Corporation Severe space weather events have the potential to pose operational threats to the North American electric power grid; both contemporary experience and analytical work support this general conclusion. A large geomagnetic storm on March 13-14, 1989, triggered a blackout of the Quebec power grid. This same storm also came uncomfortably close to causing similar widespread collapse across northeastern, upper midwestern, and mid-Atlantic regions of the U.S. power grid. More recently, Metatech has carried out investigations under the auspices of the EMP Commission and also for FEMA under Executive Order 13407 to examine the potential impacts on the U.S. electric power grid of severe geomagnetic storm events. These assessments indicate that severe geomagnetic storms pose the risk for long-term outages to major portions of the North American grid. While a severe storm is a low-probability event, it has the potential for long-duration catastrophic impacts to the power grid and its affected users. The impacts could persist for multiple years with a potential for significant societal impacts and with economic costs that could be measurable in the several trillion dollars per year range. Electric energy supply is the largest segment of energy usage in the U.S. economy, accounting for nearly 40 percent of all energy consumed (in contrast, petroleum accounts for only 22 percent of current U.S. energy consumption). In addition, the operation of many other infrastructures is dependent on a reliable and continuous supply of electricity to maintain their operational continuity. Because of the underlying importance of this service, the electric power grid is a national critical infrastructure. Severe geomagnetic storms may be one of the most important hazards and are certainly the least understood threat that could be posed to the reliable operation of the power networks. As recent detailed examinations have been undertaken concerning the interaction of geomagnetic
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report storm environments with power grids, the realization has developed that these infrastructures are becoming more vulnerable to disruption from geomagnetic storm interactions for a wide variety of reasons. This trend line suggests that even more severe impacts can occur in the future for recurrences of large storms. These trends of increasing vulnerability also remain unchecked, as no design codes have been adopted to reduce geomagnetically induced current (GIC) flows in the power grid during a storm. Unlike the more familiar terrestrial weather threats, geomagnetic storms can have a large geographic footprint that can readily encompass major portions of the U.S. electric power grid. This can create in many extra high voltage (EHV) transformers GIC flows that disrupt their normal AC operation. For large storms, widespread and simultaneous disruption can cause correlated multipoint failures and severe voltage regulation problems on the network that can threaten the integrity of the network with the potential for large blackouts. GIC also causes intense internal heating of the exposed EHV transformers, which can lead to permanent damage of these key and difficult to replace assets. Impulsive geomagnetic field disturbances are an important aspect of the geomagnetic storm environment for electric power grids and other ground-based infrastructures that can be affected by GIC. Significant power grid impacts in present day networks have been observed at relatively low levels of intensity; for example, the Quebec grid blackout during the March 13-14, 1989, storm occurred at a peak intensity of 480 nT/min, and permanent damage to large power transformers has occurred at even lower intensity levels. An analysis of both contemporary and historic storm data and records indicates that dBh/dt impulsive disturbances larger than 2000 nT/min have been observed on at least three occasions since 1972 at latitudes of concern for power grid infrastructures in the United States. In extreme scenarios, available data suggest that disturbance levels as high as 5000 nT/min may have occurred during the great geomagnetic storm of May 1921, an intensity ~10 times larger than the disturbance levels associated with the major impacts observed on North American power grids in March 1989. Present operational procedures utilized by U.S. power grid operators stem largely from experiences in recent storms, including the March 1989 storm. These procedures are generally designed to boost operational reserves and do not prevent or reduce GIC flows in the network. For large storms (or increasing dB/dt levels) both observations and simulations indicate that as the intensity of the disturbance increases, the relative levels of GICs and related power system impacts will also proportionately increase. Under these scenarios, the scale and speed of problems that could occur on exposed power grids have the potential to impact power system operators unlike anything they have ever experienced. Therefore, as storm environments reach higher intensity levels, it becomes more likely that these events will precipitate widespread blackouts of exposed power grid infrastructures. The possible power system collapse from a 4800 nT/min geomagnetic storm (centered at 50° geomagnetic latitude) is shown in Figure C.3a. The more difficult aspect of this threat is the determination of permanent damage to power grid assets and how that will impede the restoration process. As previously mentioned, transformer damage is the most likely outcome, although other key assets on the grid are also at risk. In particular, a transformer experiences excessive levels of internal heating brought on by stray flux when GICs cause the transformer’s magnetic core to saturate and to spill flux outside the normal core steel magnetic circuit. Previous well-documented cases have noted heating failures that caused melting and burn-through of large-amperage copper windings and leads in these transformers. These multi-ton apparatus generally cannot be repaired in the field, and if damaged in this manner, they need to be replaced with new units, which have manufacture lead times of 12 months or more in the world market. In addition, each transformer design (even from the same manufacturer) can contain numerous subtle design variations. These variations complicate the calculation of how and at what density the stray flux can impinge on internal structures in the transformer. Therefore the ability to assess existing transformer vulnerability or even to design new transformers to be tolerant of saturated operation is not readily achievable. Again, the experience from contemporary space weather events is revealing and potentially paints an ominous outcome for historically large storms that are yet to occur on today’s infrastructure. In recent analysis that has been conducted, it is estimated that over 300 large EHV transformers would be exposed to sufficiently high levels of GIC to place these units “at risk” of failure or permanent damage requiring replacement. Figure C.3b provides an estimate of “percent loss” of EHV transformer capacity by state for the same 4800 nT/min threat environment. Such large-scale damage would
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report FIGURE C.3 (a; left) 4800 nT/min geomagnetic field disturbance at 50° geomagnetic latitude scenario. The regions outlined are susceptible to system collapse due to the effects of the GIC disturbance. The region impacted would be of unprecedented scale and involve populations in excess of 130 million. (b; right) A map showing the at-risk EHV transformer capacity by state for this disturbance scenario. Regions with high percentages could experience long-duration outages that could extend multiple years. likely lead to prolonged restoration time and long-term chronic shortages of electric energy supply capability to the impacted regions. Given the potentially enormous implications of power system threats due to space weather, it is important to develop effective means to prevent a catastrophic failure. Trends have been in place for several decades that have acted to unknowingly escalate the risks from space weather to this critical infrastructure. Procedures based on K-index-style alerts provide very poor descriptions of the impulsive disturbance environments and lead to uncertainties about the adequacy and efficacy of operational procedures during large storms, because these indices saturate at relatively benign intensity levels. Much good work is being done to develop better means of characterizing and forecasting the threat environments so that power system operator situational awareness of this important threat is better communicated. In terms of the entire grid itself, remedial measures to reduce GIC levels are needed and cost-effective. The installation of supplemental transformer neutral ground resistors to reduce GIC flows is relatively inexpensive, has low engineering trade-offs, and can produce 60-70 percent reductions of GIC levels for storms of all sizes. Additional research work is already under way by the EMP Commission on this task. AIR FORCE CURRENT SPACE WEATHER INFRASTRUCTURE Herbert Keyser, USAF, Space and Intel Weather Exploration The U.S. Air Force (USAF) provides space weather capability for the Department of Defense (DOD) and the nation. Air Force Space Command (AFSPC) is responsible for flying space-based DOD space weather sensors, and Air Force weather procures and operates ground-based space weather sensors and operational space weather models. The Air Force Weather Agency (AFWA), working in conjunction with the National Weather Service’s Space Weather Prediction Center (SWPC), collects data, analyzes and forecasts the space weather environment, and provides that information to its customers. The USAF is focusing on a presidential policy for providing space situational awareness to the nation, to address not only DOD interests, but civil and commercial interests as well. USAF weather and AFSPC are programming to recapitalize current capabilities, develop new capabilities, and mitigate the loss of capability from the National Polar-orbiting Operational Environmental Satellite System (NPOESS) post-Nunn-McCurdy restructuring. With suitable investments, not only by DOD but also by all national partners, we can improve our space weather forecasting capabilities.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report The environment is critical in all DOD operations. Specifically, space weather impacts all military operations, whether using communications, Global Positioning System (GPS) services, or flying satellites. When problems occur, the first step is to rule out the environment—and to do this, we need to know the environmental conditions in detail. As the science improves and space weather forecasts become reliable and usable, we can then start planning around expected space weather events, and even configure systems to take advantage of the environment. Various space weather events cause effects on myriad DOD systems and missions. For instance, an energetic particle event could cause problems with troops communicating in the field, it could expose aircrews to hazardous levels of radiation, or it could interfere with the launching of a satellite. We use various systems to observe and forecast these events, both ground- and space-based; however, we need to be able to do better. This is where modeling comes into play. Just as in terrestrial weather, we cannot measure the environment everywhere. Currently, AFWA is fielding the first generation of assimilative, physics-based modeling. The Global Assimilation of Ionospheric Measurements (GAIM) model is running at AFWA, with plans to upgrade to a full-physics version in the next couple of years. Models for the magnetosphere, Sun, and solar wind are not as mature; however, AFWA is working to make sure that they can be incorporated, as appropriate. The DOD network of space weather sensors is in need of a refresh. To this end, the USAF director of weather created a plan to “get well” that focused on our role—ground sensors and modeling. The solar observing sensors and network of ionosondes have been around for a while and are becoming impossible to maintain. USAF weather is taking a phased approach to modernize these systems, with ionosondes being purchased and development work started on the optical solar observing system. We are also increasing our investment to transition current space weather modeling capabilities into operations. AFSPC is working on replacing capabilities lost on NPOESS as well as helping to sample the rest of the space environment. Because a free-flying satellite would be too expensive, AFSPC is pursuing individual sensors to fly on rides of opportunity from our national and commercial partners. They will also invest in modeling to provide knowledge of effects on their systems. At the same type, we are advocating to NASA and NOAA the development of partnerships to collect information from the rest of the space domain, particularly a solar wind sensor. As the director of weather says, space weather is a “team sport.” No one agency or institution can go it alone. To that end, we already partner with others to get the data we need. First and foremost is the SWPC. Our two forecast centers share virtually all the data, and make combined forecasts every day. Also, the U.S. Geological Survey provides vital magnetometer data to both centers. The USAF also leverages NASA JPL TEC (total electron content) data as well as helping to fund the international tracking of ACE. We have started talks with the National Solar Observatory to get GONG data to AFWA to fill in the gaps in our solar observing and help out while we upgrade our solar optical system. Of course, to take advantage of the increased data, we need to make corresponding investments in models. USAF weather is increasing its investment in its Space Weather Analysis and Forecasting System (SWAFS) to better use these data, as well as to improve modeling capabilities. AFSPC is making a corresponding investment in effects-based decision aids to take advantage of the improved capability to specify and forecast the environment. Finally, USAF weather is making sure that we continue to have the needed experts to carry out the space weather mission. We will continue to create advanced academic degree space weather officers, as well as formalize an internal USAF space weather training program. SPACE WEATHER IMPACTS ON THE ELECTRIC POWER SYSTEM Frank Koza, PJM Interconnection Exposure and Vulnerability The impacts of space weather events on the power system have been well documented. The fact that the major elements of the power system are exposed and particularly vulnerable to space weather can be disconcerting to power system operators. The superposition of extraneous currents onto the normal operational flows on power
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report Disclaimer Opinions expressed in this paper are the technical opinion of the author and are not an official statement of FAA policy. THE INTERNATIONAL GNSS SERVICE AND SPACE WEATHER Angelyn W. Moore, Jet Propulsion Laboratory, California Institute of Technology The International GNSS Service (IGS; formerly the International GPS Service) is a voluntary federation of more than 200 worldwide agencies that pool resources and permanent GNSS station data to generate precise GNSS products.1 Participants include mapping agencies, space agencies, research agencies, universities, and so on. Currently the IGS supports two GNSS: GPS and the Russian GLONASS. Over 350 permanent, geodetic GNSS stations operated by more than 100 worldwide agencies constitute the IGS network. These civilian, dual-frequency stations contribute data to multiple data centers at a minimum on a daily basis at a 30-second sampling rate; subsets contribute hourly and four times hourly, and an IGS real-time pilot project is getting under way. The IGS maintains a vendor-neutral stance and only specifies functional requirements; the network is therefore very heterogeneous in instrumentation. The IGS dataset is analyzed independently by multiple analysis centers to form the suite of IGS products, including precise orbits, clocks, station positions, and atmospheric products at a range of latencies. All IGS data and products are openly available and are used routinely by Earth scientists and related applications around the globe. Investigators leverage the collective effort of the IGS’s network, archive, and analysis infrastructure when they use IGS products with their own GPS and related data. The material presented in this talk will sample the IGS’s response to the October 2003 ionospheric storms from several perspectives. A representative station suffered intermittent loss of tracking on some or all channels during periods of this storm. The effect of such a loss of data will vary according to how many stations in the area are available and whether all of them are affected, and on the application under consideration. The IGS Ultrarapid orbits are a key IGS product that in 2003 were generated twice daily. Through the final week of 2003, some degradation of the Ultrarapid accuracy can be discerned: not all IGS analysis centers were able to contribute orbit products, and accuracies slipped a few centimeters. Nevertheless, the combined IGS Ultrarapid product achieved <10-cm accuracy for most satellites throughout the week. This would generally not have much of an impact on some types of geodetic processing, such as long-term monitoring of plate motion. However, high-rate and real-time GPS analysis is rapidly improving in detecting seismic surface waves and co-seismic displacement.2,3,4 Brief or partial loss of tracking due to space weather during a critical event could certainly degrade applications with societal and economic impacts, such as tsunami warning systems.5 The IGS historical dataset is an openly available archive that can be used to evaluate sensitivity to past space weather events; however, care must be taken when using historical data to allow for the improvement over time of the quality of equipment in the network and the density of the network. The IGS has an active Ionospheric Working Group with four centers routinely analyzing the IGS dataset to produce ionospheric total electron content (TEC) maps: Center for Orbit Determination (CODE), Berne, Switzerland; European Space Operations Center (ESOC), Darmstadt, Germany; Jet Propulsion Laboratory (JPL); and Universitat Politecnica de Catalunya (UPC). The chair is at the University of Warmia and Mazury in Poland. 1 Dow, J.M., R.E. Neilan, and G. Gendt, The International GPS Service (IGS): Celebrating the 10th anniversary and looking to the next decade, Adv. Space Res. 36(3):320-326, 2005, doi:10.1016/j.asr.2005.05.125. 2 Larson, K.M., P. Boudin, and J. Gomberg, Using 1-Hz GPS data to measure deformations caused by the Denali fault earthquake, Science 300:1421, 2003, doi:10.1126/science.1084531. 3 Choi, K., A. Bilich, K. Larson, and P. Axelrad, Modified sidereal filtering: Implications for high-rate GPS positioning, Geophys. Res. Lett. 31: L22608, 2004, doi:10.1029/2004GL021621. 4 Bock, Y., L. Prawirodirdjo, and T. Melborne, Detection of arbitrarily large dynamic ground motion with a dense high-rate GPS network, Geophys. Res. Lett. 31:L06604, 2004, doi:10.1029/2003GL019150. 5 Blewitt, G., C. Kreemer, W.C. Hammond, H.-P. Plag, S. Stein, and E. Okal, Rapid determination of earthquake magnitude using GPS for tsunami warning systems, Geophys. Res. Lett. 33:L11309, 2006, doi:10.1029/2006GL026145.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report TABLE C.1 The Suite of IGS Ionospheric Products Accuracy Latency Updates Sample Interval Final Ionospheric TEC Grid 2-8 TECU ~11 days Weekly 2 hours; 5 deg(lon) by 2.5 deg(lat) Rapid Ionospheric TEC Grid 2-9 TECU <24 hours Daily 2 hours; 5 deg(lon) by 2.5 deg(lat) The Ionospheric Working Group notified the IGS community of extremely high TEC values in the 2003 event, and the combined IGS product reflects the magnitude of the storm. Like the raw dual-frequency data from the IGS network, the IGS ionospheric products (Table C.1) are openly available and archived indefinitely, and can be valuable tools for researching past space weather events. CURRENT SPACE WEATHER SERVICES INFRASTRUCTURE William Murtagh, NOAA Space Weather Prediction Center NOAA’s Space Weather Prediction Center (SWPC) monitors, measures, and specifies the space environment and provides timely and accurate operational space weather forecasts, warnings, alerts, and data to end users in the United States and around the world. The program develops space weather observational requirements for NOAA’s sensors, ingests and processes NOAA’s (and others’) data, and transitions research into operations to improve services. The SWPC staffs a 24-hour/day Operations Center, through which both in situ and remotely sensed data and imagery flow. SWPC forecasters analyze solar images to assess the current state of the solar-geophysical environment (from the Sun to Earth and points in between). Space weather forecasters also analyze the 27-day recurrent pattern of solar activity. Based on a thorough analysis of current conditions, comparing these conditions to past situations, and using a limited suite of space weather models, forecasters are able to predict space weather on times scales of hours to weeks. NOAA radiation storm and solar flare radio blackout alerts and forecasts are dependent primarily on GOES data. All SWPC space weather alert messages for geomagnetic phenomena are based on real-time data from the Boulder-NOAA magnetometer, which can be taken as a proxy for other midlatitude locations. Most alert products correspond with the NOAA Space Weather Scales thresholds. During severe storm periods, these products are distributed both by Web access over the Internet and by direct contact with high-priority customers. These data types are also key for the U.S. weather enterprise, and they support the private and commercial sector in the development of products and services using space weather-related information. The USAF provides critical operational data from the Solar Optical Observing Network (SOON) and the Radio Solar Telescope Network (RSTN). NASA provides key science data from its research satellites (SOHO, ACE, and STEREO) and plans to provide science data from future approved missions. Data from these research satellites are now deeply ingrained in SWPC forecasting processes. The United States Geological Survey (USGS) provides key ground-based data. SWPC also receives data from many countries and their space agencies throughout the world. These diverse data streams are analyzed continuously, and that information is applied to both predictions and specifications of various aspects of the space environment. These include the behavior of the geomagnetic field, the character of the ionosphere, and the strength of the near-Earth radiation environment. SWPC currently relies on a limited suite of empirical and physics-based models. SWPC is committed to bring the new generation of numerical space weather prediction models into the forecast office. To accomplish this, SWPC will leverage the prediction and specification models developed by partner agencies (NASA, NSF, and DOD) and transition them to operations. Data-driven and data-assimilative, physics-based models will provide more accurate, longer-lead-time predictions of severe space weather storms on regional and local scales. SWPC provides a comprehensive database and Web display of space weather products. SWPC also has a product subscription service that allows customers to register to receive products via e-mail. This allows customers
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report to manage their own records and product selections, while providing SWPC with specific customer and product-usage information. Over 6500 unique customers subscribe to SWPC’s product subscription service. Many data files and products are also available on an anonymous FTP server. Selected products are also distributed on the NOAA/NWS Dedicated Broadcast Systems. The SWPC customer base is large and growing. More than 50 million files are transferred from the SWPC Web page each month. Over 500,000 files are created monthly with near-real-time data for 176 different products serving more than 400,000 unique customers every month in over 120 countries. Accurate and timely space weather information is vital in mitigating the potential impact of these storms on our technological infrastructure. Geomagnetic storms can cause widespread electrical blackouts, which could result in significant loss of life, as well as a potential GDP loss in the billions of dollars. Polar flights rerouted due to space weather can cost the airline over $100,000 per flight. If airborne survey data, or marine seismic data, are useless or poor because of solar activity, the financial impacts are significant, with costs in the $50,000 to $1 million range. Primary users of SWPC data include the following: Electric power grid operators use geomagnetic storm detection and warning systems to maximize power grid stability and to mitigate power grid component damage and large-scale blackouts. Spacecraft launch operators use radiation products to avoid electronic problems on navigation systems and thus prevent launch vehicles from going off course and being destroyed or misplaced. Spacecraft operations and design rely on space weather products to ensure spacecraft survival in the face of electronic problems. Space weather effects on satellites vary, but effects range from simple upsets to total mission failure. Manned spaceflight activities are altered to avoid or mitigate effects of radiation storms that impact crews and technological systems. Navigation systems users need space weather data as a critical input to ensure the integrity and safe use of electronic (i.e., GPS, Loran) navigational systems. Aviation uses crucial information on space weather impacts, such as communication outages, potentially harmful radiation, and navigation errors to adjust routes and altitudes. Communications operators anticipate and react to space weather over a wide range of communications frequencies used by emergency management officials, search and rescue systems, and many others. Surveying and drilling operations rely on accurate and timely space weather data for safe and efficient high-resolution land surveying and sea drilling. A growing number of customers are realizing social and economic benefits from applications of SWPC products and services. Expect this trend to continue as we become increasingly dependent on space-based systems and other technologies vulnerable to hazardous space weather. SPACE WEATHER EXTREMES T. Paul O’Brien, Aerospace Corporation In general, systems are and will continue to be designed to operate through extremes of the space environment over their designed life. This assumes an accurate climatology, which is not always available. My expertise is in the area of hazards to the health and operation of satellites, so I will use that as the backdrop for a story about extremes of the space environment. For hazards to spacecraft, the principal concerns are surface charging, internal charging, single-event effects, and total dose. Where possible, I will try to highlight general principles that can be applied broadly. The reader is advised of an important distinction: “space weather” is the description of a short-term phenomenon: a new forecast might lead to a change of operations. “Space climatology” is a long-term statistical description: a new climatology model might lead to a change of system design.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report TABLE C.2 The Present State of Space Environment Hazard Climatology of Extremes Hazard Responsible Particles Climatology Extreme Value Analysis? Internal charging 100s keV to MeV electrons Fennell et al. (2000), O’Brien et al. (2007), NASA-HDBK-4002a Yes, finite upper limit expected Surface charging 10s keV electrons MIL-STD-1809, NASATP-2361 No Single-event effects MeV protons, ions October 1989 event, Xapsos PSYCHIC model Yes, finite upper limit expected (debated) Total dose over mission eV to keV electrons, protons, oxygen Partial: Thomsen et al. (2007), JPL91 and Xapsos models, AE-8 and AP-8 Partial: only for solar particles, similar to SEE keV to MeV electrons, protons MeV to GeV protons, heavy ions (cosmi crays) Planning for Extremes Engineers typically design to operate through the extremes. It is highly atypical to intentionally design a system to have a likely susceptibility to extremes of the space environment. Trying to operationally forecast specific instances of extremes of the space environment may be of limited value: either we do not know the threshold beyond which to expect a negative impact on any specific technological system, or we do know because it’s happened before and therefore is not unusual or very extreme. There are exceptions: e.g., human extravehicular activity and large-scale infrastructure based on GPS. A solar radio burst on December 6, 2006, resulted in ~25 dB loss in the signal/noise ratio for many GPS receivers (Carrano and Bridgwood, 2008). The radio flux in the GPS L1 and L2 bands likely exceeded 106 solar flux units. Based on climatology (Nita et al., 2002), this should occur about once very 30 years, perhaps less often. For most consumer uses, an outage every few decades is reasonable. However, for critical uses, like aircraft navigation, a backup system or an engineering mitigation must be implemented (see also Gary, 2008). Extremes are often not known well, and sometimes designs fail to meet specifications: mission assurance is a systems engineering approach to ensuring that systems meet specifications; climatology is a scientific approach to ensuring accurate characterization of worst cases. At present, important aspects of space environment climatology are not explicitly included in NASA, NOAA, and NSF observation objectives. Climatology is obtained as a side-effect of some other priority (e.g., fundamental science, situational awareness), or it is not obtained at all. See Table C.2. Extreme Value Analysis Extreme value analysis is a statistical method, primarily developed in the financial and insurance industries. The analysis determines the shape of the “tail” of the statistical distribution of a quantity. It characterizes intensity of the N-year event (e.g., the 100-year flood). Sometimes (especially for geophysical phenomena) it determines a finite upper limit to the intensity or size of the largest possible event. The results allow designers to quantitatively trade design and specifications against risk. Most relevant space environment phenomena appear to have finite upper limits, but quantitative knowledge of those limits is often poor due to a relatively short history of observations. The extreme value distribution describes the distribution of largest values taken from multiple independent sample sets, where H gives the probability that any sample maximum will be larger than x. H has three parameters: position, μ; scale, σ; and shape, k. Depending on the sign of k, one obtains one of three different families of the extreme value distribution.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report FIGURE C.4 The three families of the extreme value distribution. The Weibull family, k < 0, exhibits a finite upper limit and is common in geophysical data. From O’Brien et al. (2007). Copyright 2007 by the American Geophysical Union. Reproduced by permission of the American Geophysical Union. Figure C.4 illustrates the three families of the extreme value distribution. Using a maximum likelihood method, one can obtain the parameters of H, with the most important being k. O’Brien et al. (2007) applied this method to the electrons that cause internal charging in the outer radiation belt and found a finite upper limit to the fluxes over a large spatial and energy domain. My own analysis (not shown) and that of Tsubouchi and Omura (2007) show that the tail of the distribution of the Dst index of magnetic storm intensity does include the Carrington event (September 1-2, 1859) type intense magnetic storm (Dst < −1600 n; Tsurutani et al., 2003). Extreme-value analysis thus allows us to bound the largest events expected and to put extremely large events in context. Concluding Observations With accurate climatology of extreme events, engineers can make sensible cost-benefit decisions about worst cases: harden design or accept risk. Policy makers must be aware when designs accept risk, just as with earthquakes, hurricanes, and so on. Critical systems must either be hardened or have robust backups. The following recommended actions might ameliorate the shortcomings of the present state of knowledge of space weather extremes, especially for satellite operations: First, break down cultural and systemic barriers that prevent engineers and scientists from working together to set priorities and develop solutions. Second, promote long-term space environment observation or monitoring as a legitimate scientific objective for NASA; currently, only NSF and NOAA seem to be allowed to do this, while NASA has historically flown the most capable sensors. Given the longer operational life of non-NASA missions, it may be most cost-effective for NASA to exploit more missions of opportunity on operational vehicles.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report Acknowledgments The author acknowledges useful discussion with D. Gary, NJIT, on this topic, and directs the interested reader to his presentation to IES2008 (Gary, 2008). This work was funded by the Aerospace Corporation’s Independent Research and Development Program. Available as Aerospace Tech. Report ATR-2008(8073)-1. References Carrano, C.S., and C.T. Bridgwood. 2008. Impacts of the December 2006 Solar radio bursts on GPS operations. 5th Symposium on Space Weather. New Orleans, La., January 20-24, 2008. American Meteorological Society, Washington, D.C. Fennell, J.F., H.C. Koons, M.W. Chen, and J.B. Blake. 2000. Internal charging: A preliminary environmental specification for satellites. IEEE Trans. Plasma Sci. 28(6):2029-2036. Gary, D. 2008. Cause and extent of the extreme radio flux density reached by the solar flare of 2006 December 06. 12th International Ionospheric Effects Symposium, Alexandria, Va., May 13-15, 2008. Nita, G.M., D.E. Gary, L.J. Lanzerotti, and D.J. Thomson. 2002. The peak flux distribution of solar radio bursts. Ap. J. 570:423-438. O’Brien, T.P., J.F. Fennell, J.L. Roeder, and G.D. Reeves. 2007. Extreme electron fluxes in the outer zone. Space Weather 5:S01001, doi:10.1029/ 2006SW000240. Thomsen, M.F., M.H. Denton, B. Lavraud, and M. Bodeau. 2007. Statistics of plasma fluxes at geosynchronous orbit over more than a full solar cycle. Space Weather 5:S03004, doi:10.1029/2006SW000257. Tsubouchi, K., and Y. Omura. 2007. Long-term occurrence probabilities of intense geomagnetic storm events. Space Weather 5:S12003, doi:10.1029/2007SW000329. Tsurutani, B.T., W.D. Gonzalez, G.S. Lakhina, and S. Alex. 2003. The extreme magnetic storm of 1-2 September 1859. J. Geophys. Res. 108(A7):1268, doi:10.1029/2002JA009504. Xapsos, M.A., C. Stauffer, T. Jordan, J.L. Barth, and R.A. Mewaldt. 2007. Model for cumulative solar heavy ion energy and linear energy transfer spectra. IEEE Trans. Nucl. Sci. 54(6):1985-1989. MEETING THE CHALLENGES OF NATURE—THE IMPACT OF SPACE WEATHER ON POSITIONING SERVICES SOLAR CYCLE PROGRESSION AND THE MATURING OF GPS Lee Ott, OmniSTAR, Inc. Background of OmniSTAR Groups OmniSTAR companies were formed by Fugro NV in 1996 to provide differential GPS signals to the offshore oil and gas industry and to the agriculture and geographic information system (GIS) industries. There are three operating companies responsible for the entire world. OmniSTAR, Inc., is responsible for North and South America. OmniSTAR BV is responsible for Europe, Africa, and the Middle East, while OmniSTAR Pty is responsible for Australia and Asia. The three OmniSTAR groups maintain and operate over 130 reference sites around the world. Their task is to retrieve real-time data from reference sites and to create data that are injected into over 14 L-band satellite beams. Due to the criticality of user-base operations, elaborate mechanisms are in place to ensure quality control for the inbound data and in the formation of the broadcast streams to provide integrity to users. All areas of the world are covered by more than one satellite beam, and all uplinks to the satellites can be controlled from each of the OmniSTAR network control centers (NCCs). Each satellite beam contains information for four different types of services. These services are called the VBS, HP, Glonass, and Iono. Service Descriptions The VBS service provides GPS single-frequency corrections to users that have single-frequency receivers. The process in the user receiver calculates L1 range corrections using a weighted average of near-reference-station corrections. The process creates range corrections for a virtual base station that is effectively at the user position. This process uses the Klobuchar Iono model to calculate ionosphere delays. The problem with the VBS process is that when the ionosphere delays are disrupted due to space weather phenomena, the accuracy of the VBS solution is degraded. To alleviate this problem the reference stations around the world were upgraded to
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report dual-frequency receivers, and measurements of the local ionosphere delays are calculated. These delays are then sent to the NCCs and broadcast over the satellite beams, which is our Iono service. VBS users can augment or replace the ionosphere delays calculated by the Klobuchar model with actual delay calculations from nearby stations. Further, a user with a dual-frequency receiver can actually use ionosphere-free measurements to calculate a position. However, on average the ionosphere-free solution has more high-frequency noise due to the codeless tracking of the L2 GPS signal. The Glonass service is simply a differential Glonass similar to the VBS process. Clients that have a combined GPS-Glonass receiver use this. The HP (high precision) service consists of two different modes and combinations of both. The first service provides ionosphere-free code and carrier information from its reference sites. The process in the user receiver navigates using the phase measurements only. Code measurements are used at startup to estimate the initial phase offsets and position. The second service does not use reference station information, but rather only precise orbit and clock corrections. It is a phase-based process as well. This service is referred to as XP. Another mode where users can use the reference station corrections along with orbit and clock corrections is called HP/XP. Space Weather Effects on OmniSTAR Services When ionosphere disturbances occur, the single-frequency users suffer the worst. Theoretically, the use of Iono service will alleviate some of these issues, but isolated ionosphere disturbances cannot be corrected effectively unless a reference site is extremely close to the user. Since the HP/XP service uses ionosphere-free corrections, the results will not be affected nearly as much as the single-frequency user set. However, with severe-enough ionosphere disturbances and codeless L2 tracking, receivers may not be able to maintain lock on the GPS satellites. Also, because of limited bandwidth on the broadcast satellites, corrections may be updated too slowly due to the fast changes in corrections at reference sites. If receivers cannot maintain lock on a sufficient number of satellites, then the accuracy of the solution is degraded due to rising position dilution of precision (PDOP). Many of our clients rely on positioning to maintain their operations. They use multiple broadcast beams and multiple solutions to maintain reliability and quality control. However, a sudden loss of navigation that can affect all systems can occur as a result of severe ionosphere disturbances. If usage losses cannot be predicted in advance, then it can become extremely costly to our clients: Example 1. Oil drilling from a semi-submersible that has to disconnect quickly can easily cost the operator a million dollars. Example 2. Dive boat operations can risk the lives of the divers if the mother ship is driven off position. Example 3. The cost to an agriculture user is the possible destruction of crops if the guidance system veers off. Multiplied by the number of agriculture users this could have a significant impact. What Is Needed by the User Community Better alerts and predictions are needed of areas where ionosphere disturbances will occur. Most of the Omni-STAR user base cannot interpret the information that is currently disseminated. Their only interest is in when their navigation system is going to work. OmniSTAR does send out bulletins to its users via e-mails and postings on our websites when we know that conditions are such that accuracy might be affected due to PDOP holes and possible ionosphere disturbances. However, more often than not our ionosphere predictions do not come to pass for most of our users due to the localized nature of the disturbances. Thus, our alerts oftentimes are ignored, because we have cried wolf too often.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report A SPACE MISSION PROVIDER’S PERSPECTIVE ON SPACE WEATHER Ronald S. Polidan, Civil Systems Division, Northrop Grumman Space Technology As a space mission provider, we recognize two distinct aspects of space weather phenomena: measurement and impact. We are interested in helping the science community develop and build future space weather mission concepts, and we recognize the impacts of space weather as our primary environmental factor in designing missions to survive long and well in space and deliver all the mission objectives. Northrop Grumman has a long history of building missions with space weather payloads, from the earliest Pioneer and Orbiting Geophysical Observatory missions up to the modern-day NPOESS. Since our spacecraft and instrument technology continuously evolves we must stay abreast of how this new technology will survive in the harsh environment of space. We are also very aware of the variability of space weather phenomena and the research that has shown that, prior to our short 50 years in space, space weather events occurred that were much larger and would have been more damaging than anything experienced since 1957. In 2001 the Rumsfeld Commission warned us of the possibility of a “space Pearl Harbor”—an attack on our space assets by an adversary that would leave us vulnerable. We feel there is also a real and serious threat to our space assets from major space weather events. We would also like to avoid a “space Katrina”—a natural space weather storm that severely impacts, disables, or destroys our space assets. A new factor to be considered when developing future space weather measurement missions is the availability of lower-cost launches. Almost everyone is aware of the efforts to develop much lower cost launch vehicles such as the Falcon family that is being developed by SpaceX. But there are other approaches for low-cost access to space that are less well known. The Lunar CRater Observation and Sensing Satellite (LCROSS), currently being built by Northrop Grumman Space Technology for NASA Ames, is expected to launch in 2009 as a secondary payload with the Lunar Reconnaissance Orbiter (LRO). The LCROSS mission objective is to guide the upper stage of the launch vehicle to an impact in a permanently shadowed lunar crater and analyze the ejecta for the presence of water. While this is a very exciting mission, I would like to focus on how LCROSS is getting into space. The LCROSS mission is not tiny; it has a wet mass of over 800 kg and has significant on-board propulsion. We are looking at LCROSS-based space weather mission concepts that utilize this secondary payload approach for access to space. We feel that this can offer much lower launch costs and provide a vehicle with enough propulsion to get you where you would like to be to perform your space weather measurements. Switching now to the impacts, rather than measurement, of space weather phenomena on space missions, I would like to discuss two aspects: the possible impacts of superstorms and what new technologies may be on the horizon that could mitigate some of the effects. Fortunately, the possible impacts of a superstorm on our current space assets have already been analyzed by Odenwald, Green, and Taylor (Advances in Space Research 38:280-297, 2006). This excellent paper addresses what might happen to our space assets if a superstorm similar to the 1859 Carrington-Hodgson event were to occur today. They suggest that the impacts would be widespread and severe, especially for geosynchronous and medium Earth orbit (GEO and MEO) missions. To mitigate some of the effects of such superstorms we can look to new electronics technologies that are more tolerant of space radiation. Radiation-hardened-by-design approaches may yield affordable space electronics that could help us “weather” such storms. There are a variety of potential technologies in the marketplace for us to draw from to build our future missions. Currently almost all of these technologies are in early stages of development and need both a sustained technology development and rigorous testing in an appropriate space environment before they are ready for incorporation into a mission. But the promise is high. One small example is the DuraBit™ non-volatile memory being developed by TransEL: it offers the possibility of an upset rate of 1 upset per device every 108 years in “worst-case” geosynchronous solar storm conditions, and 1 every 1012 years for quiet solar conditions. This wide range of new technology needs to be aggressively evaluated by space mission providers to assess the true value to space missions. New approaches and new technology are on the horizon that could make our next 50 years in space more affordable, better, and more secure than the first 50 years. We have a better understanding of space weather and its effects, but much more information is still needed. We are in the earliest stages of lower-cost access to space that could greatly benefit space weather measurement. New electronics technology, currently in development,
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report offers the possibility of mitigating all but the severest effects of space weather storms. We believe that a solid and integrated partnership between industry and the space weather community in developing the missions for the next 50 years of space can lead to more affordable and survivable missions and reduce the impacts of a “space Katrina” on our space assets. SPACE WEATHER IMPACTS IN RETROSPECT M.A. Shea, Air Force Research Laboratory (emeritus) and CSPAR Senior Researcher, University of Alabama, Huntsville The effect of solar-initiated disturbances on Earth’s environment has been known for more than a century. Even before the first visual observation of a solar flare, disruptions in telegraph communications were associated with geomagnetic disturbances. During World War II radar observations were disrupted during solar radio bursts, a fact that was classified until the end of the war. It wasn’t until 1946, however, that the emission of energetic particles from the Sun was recognized. The International Geophysical Year (1957-1958), which coincided with the advent of the Space Age, provided an unprecedented increase in our knowledge of the geophysical and spatial environment. The desire to exploit our spatial environment propelled the engineering community to produce increasingly smaller electronics without, at first, any concrete knowledge of the harshness of the space environment. While solar activity was very high during the 19th solar cycle (1954-1965), this magnitude of activity did not prevail over the next two solar cycles. With the exception of the events in August 1972, solar activity was relatively quiet until 1988. The events over the past two decades together with the major technological advances in the industrial community have resulted in some rather unexpected surprises for scientists, engineers, and even the general public. This presentation will summarize the chain of events from major solar activity to conditions in Earth’s environment that can lead to disruptions in what is now considered to be routine activities. Effects such as communication disruptions, electronic circuitry upsets, and increased radiation dose will be discussed. Specific examples of space weather impacts will be presented. Finally a review of historical solar proton events will be mentioned as cautionary advice that technological planners should consider the possibility of these extremely large events in the design of their operating systems. NASA’S CURRENT SPACE WEATHER SERVICES INFRASTRUCTURE O. Chris St. Cyr, NASA Goddard Space Flight Center, and Charles P. Holmes, NASA Headquarters Two NASA directorates participate in the national space weather infrastructure: the Science Mission Directorate (SMD) includes the Heliophysics Division, and the Space Operations Missions Directorate (SOMD) sponsors the Space Radiation Analysis Group (SRAG), whose concern is radiation exposure for human explorers in space. The focus of the programs of the Heliophysics Division is to “understand the Sun and its effects on Earth and the solar system.” In particular the programs seek to understand the following: How and why does the Sun vary? How do Earth and planetary systems respond? What are the impacts on humanity? In pursuit of these questions, the Heliophysics Division has laid out these research objectives: Understand the fundamental physical processes of the space environment from the Sun to Earth, to other planets, and beyond to the interstellar medium.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report Understand how human society, technological systems, and the habitability of planets are affected by solar variability and planetary magnetic fields. Develop the capability to predict the extreme and dynamic conditions in space in order to maximize the safety and productivity of human and robotic explorers. The division executes a series of programs designed to achieve these research objectives. The programs include the flight missions, suborbital flights, and an active research program employing the data gathered from these flight activities as well as pursuing investigations and technologies needed for future missions. The Heliophysics Division’s flight strategy is to deploy modest-sized space missions, frequently, to form a small fleet of solar, heliospheric, and geospace spacecraft that function in tandem to understand the coupled SunEarth system. Operating this group of spacecraft as a single observatory (the Heliophysics Great Observatory, or HPGO) allows measurements across distributed spatial scales to be linked with a variety of models and provide capabilities for improving techniques for forecasting space weather. The HPGO has 17 missions currently operating, with 2 scheduled for launch and 4 more under development. Current members of the HPGO include ACE and STEREO, which have the added feature of real-time data beacons that broadcast current space environment data for use by the space environment reporting and prediction centers at NOAA, USAF, and others. Also near-real-time data from SOHO provide valuable information on current solar activity and warnings of solar energetic particles. The SDO mission’s high-resolution solar imagery will be made available in near-real time to the space environment community. Plans are in the works to consider data beacons on the future mission RBSP (2012) and possibly MMS (2014). The Heliophysics Division solicits through NASA Research Announcements up to nine annual competitions for investigations directed at achieving the division’s research objectives. Many of the investigations involve improving models, theory, or physical interpretations fundamental to space weather topics. The Heliophysics program incorporates a data environment that retains and broadly distributes data gathered from the science instruments of the HPGO. Heliophysics sponsors NASA’s participation in the Community Coordinated Modeling Center (CCMC), a multiagency partnership to enable, support, and perform the research and development for next-generation space science and space weather models. The CCMC is a primary vehicle for demonstrating that community research models are suitable for consideration for space weather production uses. Radiation protection is essential for humans to live and work safely in space. The goal of NASA’s Radiation Health Program is to achieve human exploration and development of space without exceeding acceptable risk from exposure to ionizing radiation. Legal, moral, and practical considerations require that NASA limit postflight risks incurred by humans living and working in space to “acceptable” levels. The Space Radiation Analysis Group (SRAG) at the Johnson Space Center is responsible for ensuring that the radiation exposure received by astronauts remains below established safety limits. To fulfill this responsibility, the group provides: Radiological support during missions. Preflight and extravehicular activity (EVA) crew exposure projections. Evaluation of radiological safety with respect to exposure to isotopes and radiation-producing equipment carried on the spacecraft. Comprehensive crew exposure modeling capability. Radiation instruments to characterize and quantify the radiation environment inside and outside the human-bearing spacecraft. The SRAG is NASA’s only real-time space environment operations activity. It is a principal customer of NOAA/SWPC. NASA’s Office of the Chief Engineer is conducting a comprehensive study toward understanding agency requirements and capabilities needed to support the future human exploration program.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report POLAR OPERATIONS AND SPACE WEATHER Michael Stills, International Operations Flight Dispatch, United Airlines When planning polar operations, United Airlines relies on the NOAA Space Weather Prediction Center’s website to provide the latest space weather data. SATCOM capability is lost at approximately 82 degrees north latitude as a result of satellite positioning. United has found that solar activity can impede HF capability, and therefore United monitors absorption data in the polar region. Degraded HF in the polar region can limit an aircraft’s ability to communicate with air traffic control and the company. This situation will be accounted for in the planning process and avoided. United is also aware of proton flux levels that may be a reason for concern during solar events. The Space Weather Prediction Center in Boulder has created on its website the tab “Space Weather for Aviation Service Providers,” which focuses on the information pertinent to airline operations. In conjunction with alerts based on the NOAA space weather scales, the aviation tab provides a quick snapshot of current space weather. Airline operations require a considerable amount of preplanning, and terrestrial weather forecasts are an integral part of this process. For polar flights any and all space weather trends or forecasts are taken into account and may include avoidance of the region if the severity of the event dictates per internal policy. Space weather events do not regularly impact airline operations. There have only been several occurrences since 1999 that have caused United flights to deviate from optimum routes. Though infrequent, these events have been costly and significantly impact some of the long-haul flights. The duration of the events is also of importance. When space weather events cause operational restrictions, the results have caused delays and fuel stops for flights normally capable of nonstop operations. Current policies protect for solar events, but having information in advance and increasing lead time for planning would be advantageous for the industry. United realizes that much of the data currently available is not specifically geared for aviation.