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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report
5
User Perspectives on Space Weather Products
In the workshop session titled “User Perspectives on Space Weather Products,” the panel reviewed how various sectors and services are currently utilizing space weather forecasting and climatology products. Of particular interest was the impact that access to space weather products (data and derived information) has on their operations and customers and on society at large. The panel members were (1) Michael Stills, manager of International Operations Flight Dispatch, United Airlines, representing transportation for people and cargo; (2) James McGovern, Reliability Coordination Services, ISO New England, Inc. (an independent system operator), representing the electric power industry; (3) Lee Ott, chief scientist at OmniSTAR, which provides precision geo-location services to oil and gas exploration companies and to agriculture; (4) David Chenette, director, Space Sciences and Instrumentation, Lockheed Martin Advanced Technology Center, representing both space weather instrument providers and satellite operators and manufacturing; and (5) Kelly Hand, senior program engineer, Space Situational Awareness, Aerospace Corporation, representing the U.S. Air Force (USAF).
The panelists were asked to consider the following questions in their presentations:
Please provide examples of the types of space weather products used in your industry or organization, and how they are used. What sources of data do you use? Do you use long-term forecasts, short-term forecasts, real-time data, or historical data?
How often does space weather cause a change from “normal” operations? What data do you use to decide when it is safe to resume normal operations?
What kinds of impacts does space weather have on your companies and services and on their customers?
How would you judge the quality of the current data; i.e., how often do you get false warnings and missed warnings?
Because of the varying histories of their use of space weather data, the panelists differed in their ability to respond to all of these questions.
AIRLINE INDUSTRY PERSPECTIVE
Michael Stills described how in 1999 United Airlines began using routes over the North Pole to fly from Chicago to Hong Kong, with 12 demonstration flights. In 2007, United operated more than 1800 flights over the
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pole and made its 8,000th polar flight in April 2008, demonstrating the dramatic rise of air traffic over the North Pole. United is not alone. Thirteen carriers flew polar routes for a combined total of almost 7300 polar flights in 2007, an increase of nearly 2000 flights from the prior year.
Why polar routes? As Stills indicated, aircraft can cost hundreds of dollars per minute to operate. Polar routes reduce the time in flight. As an example, United Flight 829 on a polar route took 14 hours and 32 minutes to fly from Chicago to Hong Kong in March 2006. It carried 316 passengers and 5000 pounds of additional cargo. If the same plane had flown the best available non-polar route to Hong Kong, due to the greater headwinds it would have required 15 hours and 41 minutes, reducing the passengers to 246 and removing all 5000 pounds of extra cargo. So the polar routes allow United Airlines to avoid the strong wintertime headwinds and decrease travel time, and therefore transport more passengers and cargo, thus offering a more economical and convenient service to its customers.
Federal regulations require flights to maintain communications with Air Traffic Control and their company over the entire route of flight. United relies on SATCOM, which is communication via satellites in geosynchronous orbit (located about 22,000 miles above the equator). Aircraft lose the ability to communicate with these satellites when they go above 82 degrees north latitude (within the circle shown toward the center of Figure 5.1). In this region, aircraft communications are reliant on HF (high-frequency) radio links.
Strong solar activity causes HF radio blackouts in the polar region. Occasionally the Sun emits a shower of high-energy protons and other ions (called a solar energetic particle (SEP) event). When the protons hit Earth’s outermost atmosphere (called the ionosphere), they increase the density of ionized gas, which in turn affects the ability of radio waves to propagate.1 HF radio frequencies in the polar regions are particularly affected because the solar protons can directly reach the ionosphere in the polar cusp of Earth’s magnetic field. The radio blackouts over the poles are called polar cap absorption (PCA) events. When a solar event causes severe HF degradation in the polar region, aircraft that are dependent on SATCOM have to be diverted to latitudes below 82 degrees north so that SATCOM satellite communication links can be used. United Airlines currently utilizes the NOAA Space Weather Prediction Center (SWPC) space weather scales and alerts to plan upcoming flights and to instruct planes in transit to divert from polar routes.
PCA blackouts can last up to several days, depending on the size and location of the disturbance on the Sun that triggers them. For example, between January 15 and 19, 2005, five separate x-ray solar flares occurred that produced radio blackouts of R3 intensity. (The radio blackout scales are shown in Figure 5.2.) One of the alerts, shown in Figure 5.3, tied the expected intensity of the blackout to the X1.2 strength of the solar x-ray flare.2 For 4 consecutive days, flights from Chicago to Hong Kong could not operate on polar routes. The longer non-polar routes required an extra refueling stop in Anchorage, Alaska, which added delays ranging from 3 to 3½ hours. In total, 26 flights operated on less than optimal polar routes or non-polar routes. Increased flight time and extra landings and takeoffs increase fuel consumption and cost, and the delays disrupted connections to other flights.
Stills noted, “Ten years ago United had no reason to take space weather into consideration, but now it is something that United Airlines actively monitors, and we change and enhance our policies and procedures as more information and data become available.”
Stills indicated that United Airlines already considers in its flight planning the information and data it receives from SWPC, such as D region absorption and polar cap absorption that affects HF communications. United is also interested in K index geomagnetic status and x-ray intensity, and has just mandated that its meteorological team monitor proton flux with energy levels of 10 MEV and greater and 100 MEV and greater.
The availability of real-time solar flare monitoring and radio blackout alert services allows the airline industry to use polar routes safely. In response to an audience question, Stills indicated that accurate, high-confidence forecasts would also be useful: “Typically … the planning … for international flights … is done 2 to 3 hours in advance of the actual operation. But the infrastructure and support for an airline operation, typically things like which aircraft is assigned to, say, the Chicago-Hong Kong flight tomorrow, … is done a day in advance. The crews are assigned well in advance. They have duty time limits. All of those things come into play.”
“So it is extremely important to have an accurate prediction,” Stills emphasized. “It is very important to have it in a timely fashion and as far in advance as possible. Clearly we realize there are limitations, but to have from an infrastructure standpoint a forecast, say, 6 to 10 hours in advance would be wonderful, but from an operational
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FIGURE 5.1 Using polar routes for air traffic necessitates high-frequency radio communications at high latitudes (circular area toward center of figure), which can be disrupted by solar activity. SOURCE: Michael Stills, United Airlines, “Polar Operations and Space Weather,” presentation to the space weather workshop, May 22, 2008.
and planning standpoint, we are probably looking at a minimum of, say, 3 to 4 hours in advance, where we can make a tactical decision and still feel confident in the operation.”
ELECTRIC POWER INDUSTRY PERSPECTIVE
A geomagnetic storm that occurred in 1989 caused a blackout in the Quebec province of Canada (Figure 5.4). A transient disturbance of Earth’s magnetic field, a geomagnetic storm is caused by energetic streams of particles and fields that originate from the Sun and impact and distort Earth’s magnetic field. The transient changes in Earth’s magnetic field interact with the long wires of the power grid, causing electrical currents to flow in the grid. The grid is designed to handle AC currents effectively, but not the DC currents induced by a geomagnetic storm. These currents, called geomagnetically induced currents (GICs; also known as ground-induced currents), cause imbalances in electrical equipment, reducing its performance and leading to dangerous overheating. A major electrical transformer was damaged in the 1989 Quebec event (see Figure 5.4), resulting in significant direct financial loss to the utility in addition to other indirect losses to the northeastern U.S. and Canadian economies from the blackout. Procedures were adopted, and are currently in place, that inform electric grid operators to take actions that will prevent a blackout and to protect equipment.
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FIGURE 5.2 Radio blackout severity scales from NOAA SWPC are used by United Airlines to re-route aircraft on polar routes in response to expected radio communication blackouts. SOURCE: NOAA Space Weather Prediction Center.
In his presentation James McGovern also provided an example from October 2003 when a significant solar flare and coronal mass ejection (CME) occurred (Figure 5.5). NOAA’s SWPC issued a series of alerts, warnings, and predictions, giving power grid operators advance warning that severe space weather conditions were imminent that would put the power grid at risk. From past experience, the grid operators knew that the intensity of the DC current induced in their systems (which they monitor with their own instrumentation) scaled with the intensity of the geomagnetic storm. The intensity of the geomagnetic storm in turn is given by the K index (Table 5.1).
The power grid operators responded to warnings and to real-time space weather data provided by the NOAA SWPC (formerly the SEC, or Space Environment Center, as shown in Box 5.1) by modifying the way the power grid was operated in order to maintain adequate power quality for customers and reserve capacity to counteract the effects of space weather. Despite severe GICs, the power transmission equipment was protected and the grid maintained continuous operation. In the workshop discussion, though, McGovern pointed out that the alerts and real-time data could be improved. As an example, the K index data provided by the SWPC seemed to lag the effects on the northeastern power grid: the induced-current monitors had already reached level 2 at 01:31 on Wednesday,
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FIGURE 5.3 Example of an x-ray event alert. SOURCE: NOAA Space Weather Prediction Center, available at http://www.swpc.noaa.gov/alerts/archive/archive_01Jan2005.html.
FIGURE 5.4 A 1989 geomagnetic storm caused a blackout in the Quebec region and damaged a high-voltage transformer. SOURCE: Rodney Viereck, NOAA Space Environment Center, “Space Weather: What Is It? How Will It Affect You?,” available at lasp.colorado.edu/~reu/summer-2007/presentations/SW_Intro_Viereck.ppt.
which corresponds to K = 7, whereas the SWPC warned of K = 6 at 02:09, 38 minutes later. The SWPC uses ground magnetometer stations located in Boulder, Colorado, and Fredericksburg, Virginia, which are at geomagnetic mid-latitudes. A 4-hour delay in collecting and averaging ground magnetometer sampling (Boulder and Fredericksburg), with a consequent 4-hour lag in issuing K index alerts, requires system operators to rely on their own instrumentation, which may not be as accurate. Further, the northeastern U.S. power grids and particularly the Canadian power
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FIGURE 5.5 October 28, 2003, evolution of a solar storm. A large sunspot (brownish black spot seen in the lower half of the solar disk in the upper-left-hand image) erupted with a strong x-ray flare (bright white spot in lower half of the false-green color EIT image of the Sun, upper-right-hand image). Within minutes, LASCO detected a halo coronal mass ejection (CME) emerging from the Sun (which is blocked by the central occulting disks in the lower-left-hand image). An hour and a half after the flare, a shower of energetic protons and ions reached the SOHO spacecraft, creating the “snow” in the lower right LASCO image, confirming that the CME was headed toward Earth. When it impacted Earth’s magnetic field, this CME triggered powerful geomagnetic storms that caused problems for the electric grid in Northern Europe, polar cap absorption events, and in-orbit satellite anomalies and failures. SOURCE: NASA; see http://sohowww.nascom.nasa.gov/hotshots/2003_10_28/.
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TABLE 5.1 Geomagnetic Storm Intensity and K Index Value
GIC Severity Level
XFMRa Neutral DC Current
Corresponding Geomagnetic Storm Index
1
Minor
5-14 amps
2
Moderate
15-29 amps
K7
3
Major
30-59 amps
K8
4
Severe
>60 amps
K0
aXFMR, transformer. Shown in Figure 5.4 is an example of a high-voltage electrical power transformer damaged by GICs.
grids are located at higher geomagnetic latitudes, which are more strongly affected by geomagnetic storms. As a consequence, the magnetic disturbances at higher latitudes reach higher K levels before those at the lower-latitude stations. A general feature of geomagnetic storms is that their timing and intensity are a local phenomenon, and the best real-time data come from geomagnetic field monitoring equipment located closest to the end user of the data. As a result, system operators at higher latitudes utilize higher-latitude sources of magnetic disturbance data in addition to the NOAA SWPC and combine those data with real-time ground-current monitoring throughout their grid. These other third-party (often commercial) sources of geomagnetic data also add to the real-time data some interpretation and forecasting that are of value to electric power system operators.
In addition to real-time space weather monitoring, high-reliability near-term forecasts are critical to power system operators. Advance warning about the arrival of an earthward-directed CME is of critical importance for grid operators, allowing them time to take the measures needed to protect the grid. “The most important device that I know of out there to give us a heads-up is ACE,” McGovern noted. “ACE gives our operators about a 45-minute warning.” As Frank Koza said earlier, “We can reposition our system in probably up to 15 minutes. With 15 minutes’ advance notice we can quick-start units, reducing generation in the northern areas, picking up generation in the southern areas, offloading our tie lines, offloading our transformers, even manning key facilities so that we have operators there to switch off a transformer if they see the temperature on that transformer overloading.” And, “for the real-time operator, 45 minutes to an hour is very important. I would give it a 10 (on a scale of 1 to 10). That would be the same for the day-ahead market, which is at least 24 hours out.”
PRECISION GEO-LOCATION SERVICES INDUSTRY PERSPECTIVE
Precision geo-location services based on GPS signals arose almost simultaneously with the birth of the GPS system more than 20 years ago (see Box 5.2). Precision geo-location is critical to many users (see Figure 5.6) including,
Oil and gas companies,
Agriculture,
Mining,
Construction contractors, and
Government agencies,
as part of their operations performing,
Seismic navigation,
Dynamic and static rig positioning,
Dredging control,
Vessel and vehicle tracking,
Photogrammetry and geographic registration, and
Position confirmation and attitude monitoring using GPS kinematic solutions.
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BOX 5.1
Sequence of Events During October 2003 Storm Illustrating Power Grid Operators’ Response to Evolving Geomagnetic Storm and Space Weather Warnings
Tuesday October 28, 2003
07:37 hrs (EST) - SEC reports − X-ray event exceeded X10
12:08 hrs (EST) - SEC reports − Extended Warning: Geomagnetic K index of 4 expected
13:04 hrs (EST) - SEC reports − Extended Warning: Geomagnetic K index of 4 expected
16:39 hrs (EST) - SEC reports − Watch: Geomagnetic A index of 100 or greater predicted
22:55 hrs (EST) - SEC reports − Warning: Geomagnetic K index of 5 expected
Wednesday October 29, 2003
01:31 hrs - Maine, Chester SVC reports Level 2 ground-induced-current alarms
02:09 hrs - SEC reports − Warning: Geomagnetic K index 6 expected (3rd party forecaster predicted K8)
02:15 hrs - Maine, Chester SVC reports Level 3 ground-induced-current alarms
02:15 hrs - ISO New England
Implemented M/S # 2 Abnormal Conditions Operating Procedure for all New England effective for next 24 hours due to SMD activity. (Implementation of this Operating Procedure authorizes the New England system operator to assume an emergency condition defensive posture to protect the reliability of power system)
Cancelled scheduled 345-kV circuit breaker maintenance at nuclear plants in Vermont and Connecticut.
02:17 hrs - Quebec limiting exports to New England due to SMD activity in the Nicolet area of Montreal. (System operator had already begun to add generators to network.)
Both New England HVDC converter station imports limited to >40% to <90% of normal rating
New Brunswick imports are limited to 600 MW maximum.
ISO re-dispatching New England area generation to cover load demand
02:23 hrs - SEC reports − Alert: Geomagnetic K index 7 or greater expected
02:49 hrs - SEC reports − Alert: Geomagnetic K index 7
03:45 hrs - SEC reports − Alert: Geomagnetic K index 8
03:55 hrs - Maine, SVC reports Level 4 ground-induced-current alarms
04:41 hrs - SEC reports Alert: Geomagnetic K index of 9
07:28 hrs - SEC reports Alert: Geomagnetic K index of 7
09:26 hrs - Maine, SVC reports Level 3 ground-induced-current alarms locked with chattering, Level 4-induced current alarm spikes
09:54 hrs - Vermont HVDC imports from Quebec being reduced to below 185 MW due to increased SMD activity
09:58 hrs - Maine, SVC reports Level 4 ground-induced-current alarms
10:07 hrs - Ontario − reports voltage and MW swings observed at the Bruce Nuclear Units on Lake Huron and Pembrooke region
10:07 hrs - Ontario − reports Mountain Chute Unit #2 tripped (Pembrooke region)
10:07 hrs - Ontario − reports Bruce Nuclear Units reducing VAR output to stabilize
10:14 hrs - Maine, SVC reports Level 2 ground-induced-current alarms
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BOX 5.2
Precision Geo-location Services Evolved with GPS System
1984
First GPS receiver purchased by Chance, only 5 operational GPS satellites
1986
Fugro launches only world’s only commercial, satellite based, positioning system
1987
Fugro introduces DGPS services as GPS satellites gradually become operational
1991
S/A turned on
1992
GPS system 24 hr most locations
1993
GPS IOC
1993
Fugro fully transitions to DGPS
1993
Fugro develops OTF kinematic positioning for USACOE
1994
A/S turned on (loss of access to L2 directly)
1995
GPS FOC
1997
Fugro introduces first integrated VBS products with GPS manufacturers
1998
Problems in South America
1999
StarfixPlus dual frequency service
2000
S/A turned off
2001
Fugro launches HP service in USA
2002
Fugro introduces integrated HP products
2003
WAAS IOC
2003
Halloween Event
2004
Fugro launches integrated XP products
2006
Dec Radio Burst Event
SOURCE: Lee Ott, OmniSTAR, Inc., “Meeting the Challenges of Nature: The Impact of Space Weather on Positioning Services: Solar Cycle Progression and the Maturing of GPS,” presentation to the space weather workshop, May 22, 2008.
As an example, OmniSTAR provides differential GPS corrections to users that buy their own GPS receivers. As Lee Ott noted, “Our strategy is to give enough information to the user so that the user at his current location can make the appropriate decision about whether or not his positioning is accurate. He can make that decision himself.” This approach is important because in the diverse community of GPS users the needed level of accuracy varies.
GPS signals originate from satellites that are at about 12,000 miles altitude, and these signals have to pass through the ionosphere in order to reach GPS receivers on the ground (see Figure 5.7). The GPS signals are degraded in several ways by severe space weather. When the density of electrons and ions in the ionosphere increases in response to solar flares, the propagation delays (time delays) change, the paths that the GPS signals follow are slightly distorted (bent like light is when it passes from air to water), and the strength of the GPS radio signal is weakened. The consequence of the distortion is that the GPS receivers miss a user’s exact location. Such errors in location can have very significant effects on the operation of deep-ocean drilling platforms, for example, because if the errors are too large, the platform could move off its intended position, causing a drill line to break. And if the signal weakens sufficiently, the GPS receiver might not be able to provide the necessary location. An example of the signal fade that occurred during a significant solar flare event in December 2006 is shown in Figure 5.8. As noted by Ott, “Once [deep-ocean drilling platforms] are on station and sitting in maybe a thousand feet of water and drilling a hole, the cost of that rig is about a million dollars a day. If they are drilling a hole and something eventful happens and they lose their positioning, they have to do an immediate disconnect. The only way they can do it [is to use] blowout preventers, which basically are big scissors that just cut the pipe off. So
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FIGURE 5.6 A diverse range of businesses use precision geo-location. SOURCE: Lee Ott, OmniSTAR, Inc., “Meeting the Challenges of Nature: The Impact of Space Weather on Positioning Services: Solar Cycle Progression and the Maturing of GPS,” presentation to the space weather workshop, May 22, 2008.
FIGURE 5.7 Ionosphere-induced GPS errors. Ionospheric range delay results from normal signal propagation through the ionosphere. Scintillations result from severe ionospheric signal scattering. Amplitude fading or signal-to-noise degradation is caused by solar radio bursts. SOURCE: Paul M. Kintner, Jr., Cornell University, “A Beginner’s Guide to Space Weather and GPS,” February 21, 2008, available at http://gps.ece.cornell.edu/SpaceWeatherIntro_update_2-20-08_ed.pdf.
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FIGURE 5.8 Example of GPS signal degradation caused by a solar storm. SOURCE: Courtesy of Alessandro Cerruti, Cornell University.
you … have lost a little bit of production time, but now you have got to spend 2 days to go fish that pipe out of the hole and get back into production.”
Accurate real-time knowledge of the GPS error is critical to knowing when operations have to be interrupted and when it is safe to resume. Ott pointed out that “what we really want is … the rate of change of the ionospheric delay … because that is what kills the tracking loops in the GPS receivers, and that is what causes the errors.” He noted that current GPS monitoring systems cannot transmit data fast enough to keep up with the movement of the ionosphere. Consequently, for some uses, such as marine applications, multiple overlapping systems are employed and the results independently compared to validate positioning. When one or more systems drop out, positioning information quality control is lost. Future GPS spacecraft transmitting at higher power will mitigate some of the problems. OmniSTAR is transitioning its monitoring network to dual-frequency stations and will add Global Navigation Satellite System (GLONASS)3 services to GPS in the future, which will further improve the reliability of the error estimates.
An accurate forecast of imminent GPS outages and an accurate look ahead to when it will be safe to resume operation are essential because many GPS users need time to suspend operations and then to recover and resume operations. The current ability to forecast ionospheric disturbances is poor. Alerts based on indices of activity, such as NOAA’s K index and the X-flux index, result in many false alarms. As Ott pointed out: “It doesn’t work very well, because every time the numbers get high we alert our customers and nothing happens. This has been going on for the last several years.” Missed alarms are also an issue: “We got an … alert [last fall] from the NOAA prediction center that there was a coronal mass event that happened. They said it is not going to hit Earth, and lo and behold, it wiped us out in the Southern Pacific. It actually got as far north as the San Diego area. So prediction is obviously lacking, and we need some kind of better prediction scheme and so on that is more reliable,
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that at least the customers will pay attention to and believe us.” Since most end users of geo-location information plan their operations in advance, this industry ranks having a highly reliable and accurate 24-hour prediction at a 9 out of 10.
SATELLITE MANUFACTURING AND OPERATIONS INDUSTRY PERSPECTIVE
Satellites operate within Earth’s magnetosphere and radiation belts. David Chenette stated that “… living with space weather is a fact of life. The space radiation environment is the most significant limitation on the lifetime of the system. The [degradation of] electronics is what limits the performance of the system, and a lot of the cost of GEO communication satellites is driven by the need for 10- or 15-year missions to be able to withstand 100 kilorads [total dose].” Satellite designers need access to accurate long-term models of the radiation environment. Figure 5.9 shows the radiation belts as defined by models currently available from NASA that are used for design.
Chenette stated that unfortunately, the radiation belt models are overly pessimistic about the amount of degradation that will occur and have led to costly overdesign of many satellites in some orbits. (For instance, in GEO, new models4 show that the degradation due to radiation belt electrons can be as much as a factor of 4 to 7 lower than predicted by the old NASA AE8 model.) Less degradation implies that smaller and less expensive solar arrays can be used and will still provide sufficient power at the end of a 15-year mission and that electronics need lower-weight shielding. Since it costs roughly $40,000 to put a pound of mass into GEO, saving weight reduces cost. Yet some of the early science satellites that flew in other regions of the radiation belts collected only a few months’ worth of data, which, for lack of more complete data, are being used to represent a complete solar cycle. Long-term variability in the radiation environment has been seen when satellites have measured radiation over a solar cycle (about 11 years) or longer. This produces significant uncertainty and risk for satellites being designed
FIGURE 5.9 Satellites operate in the harsh environment of Earth’s electron belts (shown on left side only) and proton belt (shown only on the right side). SOURCE: David Chenette, Lockheed Martin Space Systems Company, “Aerospace Industry User Perspectives on Space Weather Data Products (and Models),” presentation to the space weather workshop, May 22, 2008.
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and operated in non-traditional orbits where only a snippet of a solar cycle’s worth of data has been collected. Several subsequent spacecraft missions, such as CRRES,5 have mapped portions of the radiation belts, but the data have not been assimilated into the NASA radiation belt models used by satellite designers and mission planners. There is tremendous interest in these communities for an update of the NASA radiation belt models and planned radiation belt probe missions to fill out the remaining gaps in those models.
The Sun also has a significant effect on peak environments that satellites must endure. As an example, Chenette pointed to high-energy proton data from the science satellite IMP-8 (see Figure 5.10). The rate at which high-energy particles impact spacecraft shows spikes above a slowly varying background rate (heavy line at the bottom of the peaks in Figure 5.10). “These are daily averages so that the total flux you measure over a day can be easily a thousand times the background. That is the distribution. It goes from just above the background on small little spikes to factors of 1000 or more. This is not believed to be a bounded distribution. It is like hurricanes or earthquakes. The worst ones probably have yet to be found. What we really need for designing … is the probability distribution of these intensities, because we need to be able to respond to customer requirements for being able to survive an event or being able to operate through an event. That can place very different design requirements on your system.”
Satellite designers use historical space weather data captured in climatological models to define long-term average exposures and statistical distributions of peak events. Real-time space weather and short-term forecasts (called now-casts) are also used to support launch decisions (Figure 5.11). Launch vehicles are not designed to operate in all possible weather conditions. Chenette remarked, “You don’t launch rockets in hurricanes, and you don’t launch rockets into worst-case space weather either. You can save a lot of money by not needing to do that, and just like the [ground] weather example, you can afford to wait. Given that limitation, you are not going to place a billion-dollar bet on a launch. It is absolutely essential that you understand the environment into which it
FIGURE 5.10 High-energy proton environment shows dramatic short-term spikes and slow background variability. SOURCE: David Chenette, Lockheed Martin Space Systems Company, “Aerospace Industry User Perspectives on Space Weather Data Products (and Models),” presentation to the space weather workshop, May 22, 2008.
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FIGURE 5.11 Launch vehicle lifting from pad. Launches are postponed if ground weather or space weather makes a launch too risky. SOURCE: U.S. Air Force.
goes, and that that environment is safe enough. What we really need in this case is the ability to anticipate enough in advance so that we know that the more susceptible launch vehicle—because it only has to work properly for a little while—will be flying through a safe environment.”
Once a satellite is launched and is on orbit, the satellite operators will continue to monitor the space environment. Most of the equipment on a satellite has to operate 24 hours a day, every day, for the entire 10- to 15-year life of the satellite regardless of space weather. But other equipment is used only intermittently, behind the scenes. Examples are thrusters that are used to counteract the naturally occurring drift of satellites away from their desired orbits. As with launches, satellites operators will review current space weather conditions, such as high-energy electron environments, to determine if the environment is calm or disturbed. If the environment is disturbed, the thruster operation is postponed, reducing the risk to the satellite and its customers.
Making this operational judgment call requires that current weather data, such as the GOES6 energetic electron data (Figure 5.12), be obtained from the NOAA SWPC. The plot in Figure 5.12 shows that the environment (and the solar conditions that drive it) has some limited repeatability, which allows making forecasts with some confidence. But other phenomena, such as solar flares (see the GOES 13 image of a solar flare in Figure 5.13) and CMEs, are not accurately forecast, and real-time monitoring is essential to reducing risk for satellite operators. “We really need to be able look at the Sun and know not only that there is an active region that [might] create a major storm, but also what the signatures are of the precursors [that forecast] these major events. I think there is
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FIGURE 5.12 High-energy electron flux history shows some repeatability, suggesting that short-term forecasts with some confidence might be made. SOURCE: David Chenette, Lockheed Martin Space Systems Company, “Aerospace Industry User Perspectives on Space Weather Data Products (and Models),” presentation to the Space weather workshop, May 22, 2008.
FIGURE 5.13 Solar flare image. Forecasting these solar flares and the adverse space weather they create requires more data and models than are currently available. SOURCE: NASA.
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every reason to believe that with the much higher resolution information that is coming to us from the SDO,7 we will have the science necessary to support those [forecasts].”
Despite the best efforts of satellite design engineers, anomalies due to unexpected interactions between satellites and space weather continue to occur. Having the ability to re-create the environment around the satellite at the time leading up to the anomaly is critical to determining if space weather caused the anomaly or not. Since most satellites do not carry environment monitors, anomaly investigators rely on data from other satellites and on models that extrapolate the environment from where it was observed to the location of the satellite that had the anomaly. So the ability to collect historical real-time data and extrapolate to other locations is also vital to satellite operators. On a scale of 1 to 10, with 10 being highly desirable, Chenette stated that “without long-term [climatology] predictions we would be dead—that is a 10. Being able to have a few days’ advance notice of higher activity would be an 8 or 9 [for launch vehicles and space operations, including manned operation on the Moon and in transit to Mars].”
U.S. AIR FORCE PERSPECTIVE
U.S. presidential policy assigns the responsibility to protect the space assets of the military, the intelligence community, the civil space assets, and the assets of allies to the U.S. Strategic Command, which is the operator of the U.S. Department of Defense (DOD) space systems and services. To fulfill that responsibility requires that the USAF maintain space situational awareness. That awareness includes monitoring the space environment.
Space weather has effects on the performance of DOD space assets that are similar to those it has on the civil and commercial assets discussed by other presenters in this session (Figure 5.14). Communication and navigation services used by DOD are affected by ionospheric disturbances that cause fading and scintillation of RF signals in equatorial regions and HF blackout in the polar regions. Potential loss of signal affects communication and
FIGURE 5.14 Military systems are affected by diverse space weather conditions. SOURCE: Kelly J. Hand, U.S. Air Force, “Space Weather—A DOD User Perspective,” presentation to the space weather workshop, May 22, 2008.
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report
FIGURE 5.15 A wide range of space- and ground-based systems are utilized to create situational awareness of space weather and its impacts. SOURCE: Kelly J. Hand, U.S. Air Force, “Space Weather—A DOD User Perspective,” presentation to the space weather workshop, May 22, 2008.
associated command and control of troops. GPS-aided systems used by military operations can also be affected. Increased atmospheric drag resulting from geomagnetic storms affects orbits of satellites and orbital debris. The Air Force Space Command has to update models of the orbits of debris with the latest sensor data in order to forecast potential collisions with satellites and the International Space Station (ISS). The ISS has made collision avoidance maneuvers in response to forecasts that show that debris will get too close for comfort.
The example of space station debris avoidance shows that space situational awareness is more than just observing space weather. Kelly Hand summarized the actions necessary to address the space weather aspect of situational awareness: (1) observe environmental conditions, using space- and ground-based sensors; (2) process sensor data, using environmental models to form complete pictures of the actual and forecast environment; (3) determine effects of the actual or forecast environment on systems and mission operations; (4) integrate effects into situational awareness, planning to mitigate those effects. The USAF relies on collaborative partnerships with other agencies in order to obtain and use the data it needs to develop situational awareness (Figure 5.15). Hand noted that “from a space operational perspective … we need to have an understanding of what is happening in the natural space environment in more detail and more rapidly than we are currently experiencing today. Also, information concerning its [space weather’s] effects needs to be effectively integrated…. Our bottom-line concern with space weather is to determine how badly, when, and where space weather impacts our space systems and services and what we can do with that information to better protect and deliver those space services.”
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Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report
SUMMARY
Space weather clearly affects our technological systems and society. This workshop session presented four diverse examples of industries that manage or support technological systems that are directly affected by space weather: electrical power grid operators; precision geo-locations services; satellite manufacturing, launching, and operations, and the U.S. Air Force. In an effort to mitigate the impacts of space weather, each has responded by monitoring and reacting to current conditions, utilizing existing space weather data sources and services, and adding its own industry-unique assessment.
Space weather data are collected by satellites or ground-based observatories (e.g., ground-based magnetometer stations that study geomagnetic fields or riometers that monitor the state of the ionosphere). Some government services, such as NOAA’s SWPC, have been established that provide some data collection, interpretation, and dissemination services that are utilized by industry (e.g., solar proton event intensity is used by spacecraft operators when making launch decisions, and by airlines in deciding on polar route diversion). Some rudimentary forecasting and alerts have been established and are utilized by industry to prevent imminent problems (e.g., power grid operators use ACE satellite data to secure the grid against an imminent geomagnetic storm). These services have allowed industries to minimize the disruptions caused by space weather, to the benefit of their millions of customers and society as a whole. The existing systems in place were deemed extremely beneficial (10 on a scale of 1 to 10) by the session’s speakers.
The session’s speakers indicated, however, that more could be done. First, a plan is needed to transition from scientific research platforms to continuously operating platforms in order to maintain the current data streams and alerts with continuous and redundant systems. Some of the research assets that industry currently depends on (e.g., ACE) are nearing the end of their life, and no plan is in place for a replacement. Second, each industry representative indicated that a reliable 24-hour forecast would be of significant value to reducing risks and disruptions, typically ranking it between 8 and 10 on a scale of 1 to 10. Currently available warnings are of little value to some industries, such as precision geo-location, because of the large number of false alarms and missed alarms.
In short, workshop participants learned that many industries have found a use for space weather data and have come to depend on current sources for that data to safeguard their technological systems and the services they provide to society. The industries represented in this session want to continue to have access to the near-real-time data they currently get, and they would eagerly adopt credible 24-hour forecasts when available.
NOTES
1. A description of polar cap absorption triggered by solar proton events can be found at http://www.windows.ucar.edu/spaceweather/polar_com.html. A more technical source is J.D. Patterson, T.P. Armstrong, C.M. Laird, D.L. Detrick, and A.T. Weatherwax, Correlation of solar energetic protons and polar cap absorption, J. Geophys. Res. 106(A1), 149-163, 2001.
2. The high-frequency (HF) radio blackouts covered by the R scales occur on the sunlit side of Earth, primarily at lower latitudes, and are a type of disturbance different from than the polar cap absorption (PCA) events affecting polar aircraft HF communications. PCAs are caused by solar protons and not by x-rays. The SWPC monitors the solar energetic particle flux in real time and issues alerts when the proton flux exceeds a specified threshold. The solar proton flux is categorized by a different set of levels, called the S scale (see http://www.swpc.noaa.gov/NOAAscales/index.html#SolarRadiation Storms). So the S scale, and not the x-ray intensity categorized by the R scale, is the proper scale to describe the intensity of the solar radiation storm and associated PCA. However, the coronal mass ejection (CME) that causes the PCA, if it is Earth directed, is often associated with a strong solar x-ray flare. The x-rays reach Earth in minutes, while the slower protons typically require many tens of minutes to hours to reach Earth, so x-rays provide an early warning that is not provided by the real-time proton monitors. Alerts tied to x-ray flares and described by the R scales are therefore useful to airlines, even though the x-rays have no direct connection to PCAs. Confirmation that a CME has occurred, is Earth directed, and will trigger solar energetic particle and PCA events can be given by satellites. This was done using IMP8 and is now being done by the Advanced Composition Explorer (ACE) and Solar and Heliospheric Observatory (SOHO).IMP8, launched in 1973 and operated for 28 years, was the last of the Interplanetary Monitoring Platform spacecraft. It carried 12 instruments designed to monitor the interplanetary plasma, electric and magnetic fields, and high-energy cosmic-ray environments near Earth. See http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1973-078A and J.D. Patterson, T.P.
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Armstrong, C.M. Laird, D.L. Detrick, and A.T. Weatherwax, Correlation of solar energetic protons and polar cap absorption, J. Geophys. Res. 106(A1), 149-163, 2001.From its location at the Lagrangian point L1 about 1.5 million km from Earth and 148.5 million km from the Sun, ACE has a prime view of the solar wind, interplanetary magnetic field and higher-energy particles accelerated by the Sun, as well as particles accelerated in the heliosphere and the galactic regions beyond. ACE also provides near-real-time 24/7 continuous coverage of solar wind parameters and solar energetic particle intensities (space weather). When reporting space weather ACE provides an advance warning (about 1 hour) of geomagnetic storms that can overload power grids, disrupt communications on Earth, and present a hazard to astronauts. see http://www.srl.caltech.edu/ACE/ace_mission.html). More detail can be found in Stone et al., The Advanced Composition Explorer, Space Science Reviews 86, 1, 1998.SOHO also obits at the L1 Lagrangian point, where it continuously monitors the Sun with 12 different instruments. Of particular use for space weather warnings are EIT (Extreme Ultraviolet Imaging Telescope), which can detect eruptive solar flares, and LASCO (Large Angle and Spectrometric Coronagraph), which can detect coronal mass ejections that may impact Earth’s magnetosphere. See http://sohowww.nascom.nasa.gov/about/docs/SOHO_Fact_Sheet.pdf. Sample EIT and LASCO images are shown in Figure 5.5.
3. GLONASS is based on a constellation of active satellites that continuously transmit coded signals in two frequency bands, which can be received by users anywhere on Earth’s surface to identify their position and velocity in real time based on ranging measurements. The system is a counterpart to the U.S. GPS, and both systems share the same principles in their data transmission and positioning methods. GLONASS is operated by the Coordination Scientific Information Center (KNITs) of the Ministry of Defense of the Russian Federation. See http://www.spaceandtech.com/spacedata/constellations/glonass_consum.shtml.
4. Boscher, D.M., S.A. Bourdarie, R.H.W. Friedel, and R.D. Belian, Model for the geostationary electron environment: POLE, IEEE Trans. Nucl. Sci. 50(6), 2278-2283, 2003.
5. CRRES, Combined Release and Radiation Effects Satellite. See http://nasascience.nasa.gov/missions/crres.
6. GOES, Geostationary Operational Environment Satellite. GOES 13 is the most recent addition to the in orbit fleet of GOES satellites and carries the primary solar x-ray imager. These satellites provide continuous terrestrial weather monitoring (http://www.goes.noaa.gov/) and monitoring of solar activity and space weather (http://www.swpc.noaa.gov/).
7. SDO, Solar Dynamics Observatory. SDO is designed to improve understanding of the Sun’s influence on Earth and near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously. See http://sdo.gsfc.nasa.gov/.
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