Space Weather: The Impact on Security and Defense

  • J. Janssens
  • D. BerghmansEmail author
  • P. Vanlommel
  • J. Andries
Living reference work entry


Space weather refers to variations induced by the Sun of the Earth’s space environment and the impact that these variations can have on technological systems and human health. During space weather events, technology, such as radio communication and GNSS positioning, can be seriously affected. Space weather can cause the loss of satellites, increase radiation levels at aeronautical flight levels and on the ground, and has the potential to catastrophically damage power grids. We review the space weather cause-effect chains from the source to the affected technologies with special attention to the impact on security and defense.


Besides being an exciting scientific discipline, space weather is increasingly recognized as a source of risks to critical infrastructures. Governmental and commercial organizations become progressively aware of their vulnerabilities to the impact of space weather on technological systems and human health. Space weather thereby evolves along the same path as meteorological weather: end users require to be informed on the impact the environment has on their activities, both on average over long time scales as well as operationally in real time.

Most space weather is ultimately due to events in the solar atmosphere such as solar flares, solar energetic particle events, coronal mass ejections, and coronal holes. The impact of these events propagates through interplanetary space and can directly affect technologies and astronauts deployed in space, or indirectly through disturbances of the Earth magnetosphere and ionosphere. Space physics is however only part of the story; the final impact experienced by the end user is critically dependent on the details of the technology and the local environment. Space weather is therefore undeniably multidisciplinary, spanning different space and geophysics as well as engineering domains.

The difficulty with setting up a user-oriented service is that the required space weather and technology expertise is scattered over various disciplines, over many organizations (government organizations, research institutes and companies) in different countries. Several international organizations are therefore taking initiatives to create collaborative frameworks to bring together the required expertise. The World Meteorological Organization (WMO, a specialized agency of the United Nations) has created the Inter-programme Coordination Team on Space Weather (ICTSW) that is tasked to worldwide standardize and enhance the exchange of space weather data and services. In the past years, the Space Situational Awareness (SSA) program of the European Space Agency (ESA) brought together many European space weather assets in a coordinating framework. Later this year, ESA will regroup its space weather activities in a “Space Safety & Security” pillar at the ESA Ministerial Council "Space 19+", scheduled end 2019.

Section “Space Weather from the Sun to the User” of this chapter provides an overview of space physics phenomena and the potential impact they have on technologies. This is further illustrated in section “Historical Space Weather Events with Defense and Security Impact” with a sample of historical space weather events selected for their relevance to security and defense. Section “Space Weather as a Challenge” addresses the challenges space weather poses for (observational) research, for societal risk handling, and finally as a security and defense issue. The last section provides the conclusions on this chapter on space weather.

Space Weather from the Sun to the User

The Sun is a variable star at only 150 million km from the Earth. It is a plasma ball, i.e., a hot ionized gas where the interaction of its electrical and magnetic energy makes its dynamics and variability. Its variability is characterized by the 11-year cycle observed in the counts of the sunspot index (Fig. 1). Sunspot are dark features appearing in groups (Figs. 2 and 4) where the solar magnetic field pierces through the visible surface of the Sun. Higher up in the solar atmosphere, in the solar corona, the sunspots expand in so-called active regions composed of magnetic loops that connect with nearby sunspot groups (Fig. 7). In contrast, in “coronal holes,” the magnetic field is not bundled in strong coronal loops, nor does it reconnect to other place on the solar atmosphere, but expands outwards and fills most of the interplanetary space with the (fast) solar wind. The Sun rotates around its axis in roughly 28 days, with the solar poles taking a few days longer for a complete rotation than the solar equator. Also, the (fast) solar wind is swept around as a fire-hose stream passing by the Earth with 28-day recurrence.
Fig. 1

The international sunspot number characterizing the 11-year magnetic activity cycle of the Sun

Fig. 2

White light drawing from the Mount Wilson Observatory on 19 September 1941, showing the sunspot group responsible for the brilliant aurora the night before. Note the remark from the observer-on-duty in the lower right coroner (“Aurora last nite”). The Mt. Wilson 150-Foot Solar Tower is operated by UCLA, with funding from NASA, ONR and NSF, under agreement with the Mt. Wilson Institute (

With increasing complexity, the magnetic active regions in the solar corona tend to become unstable to so-called magnetic reconnection thereby producing energy emissions, called solar flares, over the entire electromagnetic spectrum. Solar flares are categorized according to their emission in soft X-rays using a logarithmic scaling (Fig. 8). The most violent class of flares (X-class) amounting to an increase of a factor 10,000 in solar X-ray emission with respect to the background level (A-class) observed on quiet days. A similar magnetic reconnection process can lead to coronal mass ejections (CMEs) whereby a large blob of mass is expelled from the solar atmosphere into the solar wind. If the propagation of the CME is faster than the ambient solar wind, then the CME fronts can steepen into shock waves. Solar plasma particles can be accelerated to near-relativistic speeds, either in solar flares or in shock waves. The particles escape away from the Sun into space. Moving through space, these electric particles are forced to follow the magnetic field lines present in the space. These fast particles are called “Solar Energetic Particles” or in short SEPs.

Given its proximity, the Sun drives space weather around the Earth on three timescales:
  1. 1.

    Within 8 min, the electromagnetic radiation emitted by flares and travelling at the speed of light

  2. 2.

    Within an hour, SEPs travelling at near-relativistic speeds from flares or CME shocks

  3. 3.

    Within a day, the bulk mass of the fastest CMEs (~2000 km/s)


Life on the Earth’s surface developed experiencing little or no influence from the above-mentioned solar drivers of space weather because the Earth is surrounded by different protecting layers. The magnetic field of the Earth expands outwards in space and creates a magnetic bubble (the magnetosphere) from which the solar wind is deflected. Under the pressure of the solar wind, the magnetosphere is deformed on the sun-light “day” side but remains big enough in normal conditions to expand beyond the orbit of geostationary satellites. Under the impact of CMEs or fast solar wind stream however, the magnetosphere temporary further deforms and later resettles. This process is called a geomagnetic storm and is often associated with aurora near the magnetic poles. In the northern hemisphere, these polar lights are most often seen from Scandinavia, Canada, Alaska, and Siberia. By creating large-scale induction currents, geomagnetic storms can also lead to power grid collapse. On longer timescales, geomagnetic induction currents through oil pipelines lead to enhanced corrosion.

The top layer of the Earth atmosphere (roughly from 60 to 1000 km) protects us from extreme ultraviolet (EUV) and X-radiation from the Sun and is called the ionosphere. The ionosphere reflects HF (high frequency) radio waves and is therefore important for radio communication. The ionosphere is a reactive environment which can be strongly influenced by solar flares, by geomagnetic storms and by solar energetic particles. Disturbed ionospheric conditions can lead to HF radio blackouts, degraded satellite communication, and GNSS (Global Navigation Satellite Systems) positioning errors. Under the influence of solar radiation, satellites in low Earth orbit can experience enhanced drag at times the ionosphere is “thickened.”

Solar energetic particles reach the Earth environment at near-relativistic speeds along the interplanetary magnetic field embedded in the solar wind. They are an immediate risk to astronauts and spacecraft electronics. They are deflected by the Earth magnetosphere towards the magnetic poles of the Earth where they collide with atmospheric particles creating a shower of secondary radiation. The most energetic SEP events can however strike anywhere on the Earth with their shower of secondary radiation reaching the ground (so-called ground-level events, GLEs). During such strong SEPs, airplane crew and passengers risk ionizing radiation, and notably during polar flights.

Not unlike earthquakes, space weather events are exponentially distributed with small events being much more numerous than large events. The largest events in recorded history are referred to as extreme space weather. Among geomagnetic storms, the classical reference is the “Carrington event” in 1859 which made telegraph systems, the most advanced technology at the time, fail all over Europe and North America. If such an event would happen again, modern technology would be catastrophically affected. The chance for such extreme events to occur again in the next 10 years is only 12% (Riley 2012). Cases of extreme space weather are thus high impact-low probability events.

Historical Space Weather Events with Defense and Security Impact

In this section, we first give an historical account of some noteworthy space weather events with military impact.

Polar Lights as the Ultimate Weapon

During the Second World War, both belligerent parties made use of the bright shine of the polar lights to attack critical assets of the adversary. A noteworthy example took place in September 1941 (Love and Coïsson 2016). Greenwich sunspot group 1,393,703 appeared from behind the eastern solar limb on 10 September. During its 2-weeks transit over the solar disk, it continued to grow in size and complexity, making it all the way into the Top 50 of largest sunspot groups of the last 170 years! The region was very flare active, and a particularly strong eruption over this sunspot group was observed with the Greenwich Observatory spectrohelioscope in the morning of 17 September. Barely 20 h later, magnetometers on Earth went haywire when what is now known as a coronal mass ejection (CME) struck the earth’s magnetic field. Starting around 09:00 UT on 18 September, severe to extremely severe geomagnetic storming levels were continuously recorded for a period of 24 h, a level of geomagnetic activity that has not since been matched (Cliver and Svalgaard 2004). The resulting aurora was observed as far south as New Mexico and California (Fig. 2). In Chicago, motorists parked on the highways had caused a traffic jam as they sought a clear view of the celestial spectacle. The press used literary one-liners such as “celestial pyrotechnics,” “neon lights,” or “ethereal blitz” to describe the impressive event. Some citizens even wondered if a new type of anti-aircraft search battery was being tested.

The true effects on war took place in Europe, where the British Royal Air Force carried out a raid on a German supply base in the Baltic Sea, whereas the Germans bombarded Leningrad, each under the lights of the aurora borealis. In the North Atlantic, German U-boats were operating to sink eastbound ships supplying Great Britain. During the night of 18–19 September, the captain of the U-74 recorded in his war diary that the conditions were “as bright as day.” An allied convoy consisting of cargo ships and accompanying anti-submarine warships (“corvettes”), which normally would have been hidden in the dark of night, was detected. Just a few hours later, a decisive torpedo was fired hitting the corvette HMCS Lévis, nearly cutting the vessel in two. Shortly afterwards, the HMCS Lévis sank leaving many casualties.

The Disappearance of the HMS Acheron

Since the start of the measurements in the early 1940s, only 72 GLEs have been recorded, qualifying them as rare. The strongest GLE occurred on 23 February 1956, and increased radiation levels on several locations by several thousands of percent (Bieber et al. 2005; Fig. 3).
Fig. 3

On 23 February 1956, neutron monitors around the world recorded a strong increase in neutron counts, what turned out to be the strongest ground-level enhancement ever recorded. A GLE is a rare event with only 72 registrations since the start of the observations in the early 1940s. Most GLEs do not reach 100% in neutron counts increase, corresponding here to halfway between 0% and the first gridline (200%). This testifies of the formidable strength of the 1956 event. Plot from the Oulu Cosmic Ray Station of the University of Oulu, Finland (

Coincidentally, the HMS Acheron, a submarine of the Royal Navy, was performing arctic trials in the Denmark Strait between Iceland and Greenland. The 1,123-ton Acheron was a sister ship of the Affray, which sank in the English Channel a few years earlier, leaving many casualties. When the Acheron did not respond to a routine radio check on 24 February at 10:05 a.m., the Admiralty flashed a “sub-sunk” order, signaling an immediate search with all available ships and planes. Royal Air Force planes roared off for Reykjavik, Iceland, to set up a base for search operations. U.S. Air Force units on Iceland already were standing by. Ships steamed out from Scotland and Iceland. Three hours later, the British minesweeper Coquette radioed that she had made “visual contact” with the sub in gale-swept seas. The Acheron then proceeded to Iceland, and the Admiralty called off the search for the British submarine, which was feared lost for nearly 6 h. It was quickly pointed out that the unusual sunspot activity over the past 2 days might have been the cause of the radio blackout, as gigantic explosions on the Sun had bombarded the Earth with cosmic rays, interfering with communications. In Copenhagen, the Danish government’s telegraph authority said no radio messages had been received from Greenland stations since early morning on 23 February. “Frankly,” a spokesman for the authority said, “we cannot see how a vessel could get signals through while we cannot receive a word from powerful land stations.” (from the “Amsterdam Evening Recorder,” 24 February 1956).

Jamming Missile Warning Systems

In 1967, the Cold War between the Soviet Union with its satellite states (USSR) on the one hand and the United States and its allies on the other hand was in full swing. The USA had a stockpile of more than 30,000 nuclear warheads, while the USSR was making a recovery effort to exceed that number. Ballistic missiles that could carry such warheads were deployed at an increasing pace, and radar systems to detect such missiles were being operated. Tension was high and pushed even further by the ongoing race to the Moon, the continued launch of spy satellites, and other conflicts such as between Egypt and Israel. It was against this backdrop of geopolitical and military turmoil that a large and complex sunspot group appeared at the Sun’s east limb on 17 May. Further increasing in size during the next days, the region started strong flaring activity from 21 May onwards, which would last for a full week. The strongest flare (X6) took place on 23 May around 18:46 UT, which was at sunset for European countries, but near local noon for the central United States (Fig. 4). It was followed by another strong flare (X2) at 19:53 UT. These extraordinary solar eruptions manifested themselves very strongly over all portions of the electromagnetic spectrum, and extreme, hours-long solar radio bursts (i.e., burst in the radio part of the solar spectrum) were recorded. At frequencies of 606 MHz, peak flux densities reached 373,000 sfu (solar flux units), making it the strongest solar radio burst observed up to that time, and of the entire twentieth century. For comparison, typical values for the “undisturbed” flux density at this frequency are somewhere between 30 and 45 sfu.
Fig. 4

The famous sunspot group responsible for the very high solar activity on May 1967. On top, a white light drawing by the USET solar telescope (Royal Observatory of Belgium, Brussels, on 23 May (10:30 UT). The bottom picture is an H-alpha image taken on 19:32 UT at Sacramento Peak when the X6 flare was still in progress. The size of the bright flare ribbons, covering most of the sunspot group, testifies of the strength of the event (Image from the Flare Patrol H-alpha instrument, NSO/AURA/NSF,

The solar radio bursts significantly disturbed the United States’ Ballistic Missile Early Warning System, BMEWS for short (Knipp et al. 2016). This radar system operated at 440 MHz from sites in Alaska, Greenland, and the United Kingdom. During the 23 May event, all the BMEWS radar systems had a good view on the Sun, with the Greenland radar particularly well aligned. In response to the solar radio bursts, the radar screens showed many “impacts” which were subsequently interpreted as jamming by the operators who had never witnessed such an intense radio event. Logically, Cold War military commanders viewed full-scale jamming of surveillance sensors as a potential act of war and positioned their bombers in a ready-to-take-off position. The decision to launch or not to launch is well worth noting, because in view of the tense political situation in May 1967, a full-scale aircraft launch by the allied forces could have been very provocative and, just as importantly, difficult (if not impossible) to abort in view of the impaired radio communications. Fortunately, and despite the limited data available at the time, solar forecasters from the USAF Air Weather Service were able to extract sufficient information from solar and radio observations to convince high-level decision makers at NORAD (North American Air Defense) that the Sun was the likely culprit in contaminating the BMEWS radar signals. This key element defused the critical situation, and the decision was taken to return aircraft and alert status to their normal levels. Further details on this event and its space weather impacts, as well as on the effects from the related extremely severe geomagnetic storm, can be found in Knipp et al. (2016).

Unexpected Detonation of Sea Mines

Over the years, the solar storm of 4 August 1972 has reached a legendary status among space weather scientists. This storm was very similar to the famous Carrington event in 1859, except for the aurora which was not seen from low geomagnetic latitudes. The main eruption took place during the morning of 4 August and was accompanied by a powerful proton event that reduced the life expectancy of solar panels aboard satellites with no less than 5 years. Yet, things could have been much worse. Indeed, the storm occurred right between the Apollo 16 and 17 missions. If astronauts had been walking on the Moon when this proton event took place, then they would most likely have suffered radiation sickness (Cucinotta et al. 2010; Fig. 5). The CME accompanying the eruption still holds the record for being the fastest CME travelling the Sun-Earth distance. No CME has ever done better than 14.6 h (Cliver and Svalgaard 2004). This achievement was most likely the consequence of eruptive activity during the hours and days prior to the main eruption, clearing the path for the powerful 4 August CME. When it arrived at Earth, the magnetopause, usually at about 10 Earth radii distance, was pushed back to the Earth to only about 5 Earth radii, suddenly exposing several satellites to the wrath of the disturbed solar wind. As the subsequent geomagnetic storm unleashed all its power, some of the magnetometers on Earth went off-scale, and aurora was bright enough to cast shadows. As just recently revealed by the scientists (Knipp et al. 2018), this severe geomagnetic storm had also another effect which had been buried in the military archives for more than 40 years. Indeed, back in 1972, the United States were at war with Vietnam. In an attempt to isolate North Vietnam from the rest of the world, magnetic-influence sea mines (“Destructors”) had been dropped into the coastal waters of North Vietnam just 3 months prior. On 4 August, aircrews reported the sudden detonation of some two dozen of sea mines near Hon La in just 30 s. Aerial observations indicated evidence of some 4000 additional detonations along the North Vietnamese coast during the first weeks of August. The US Navy quickly concluded that the magnetic field variations were the cause of these detonations, in line with measurements from magnetometers in nearby locations such as Manila, the Philippines. This conclusion led to the radical decision to replace all the magnetic-influence-only sea mines with magneto/seismic mines, meaning there were now two triggers needed before the sea mines could detonate.
Fig. 5

Astronaut Eugene A. Cernan checking out the Lunar Roving Vehicle (LRV) during the Apollo 17 mission in December 1972 (Credits: NASA). Just a few months earlier, energetic particles released during a strong solar eruption would have caused radiation sickness if any astronauts had been walking around on the lunar surface at that time

The Battle of Takur Ghar

So far, the cited examples took place during record setting space weather storms. However, the following case illustrates that even mild disturbances, enhanced by a series of unfavorable conditions, can also lead to insecure situations.

Operation Anaconda took place in Afghanistan from 1 to 18 March 2002. It was a large-scale international military campaign led by the United States aiming at the destruction of Al Qaeda and Taliban forces. An intense battle took place during the morning hours (before dawn) of 4 March on Takur Ghar, a 3191-m high mountain top, as US Special Operations Forces came under heavy fire from the Al Qaeda and Taliban forces. A Chinook helicopter was directed to rescue the team. However, in view of the rocket-propelled grenades and heavy machine guns that the insurgents were using, a SATCOM (Satellite Communications) message was sent to the Chinook to avoid the mountain top. Unfortunately, and despite repeated attempts, the Chinook helicopter never received that critical message. It landed on the top of Takur Ghar and came immediately under intense fire, resulting in several casualties.

A subsequent analysis of the incident blamed the radio outage on poor performance of the UHF (ultra high frequency) radios on the helicopters as well as on terrain radio interference. However, in 2014, Michael Kelly and his team of researchers from the John Hopkins University came to a different conclusion, offering a viable alternative for the outages (Kelly et al. 2014). Utilizing a model that uses UV (ultraviolet) data from the TIMED spacecraft to retrieve the 3D electron density, they came to the conclusion that a combination of ionospheric disturbances with multipath effects (multiple radio reflections from the mountainous terrain) could also have caused the decreased communication links (Fig. 6).
Fig. 6

Sketch prepared by ROB/GNSS (Dr. Nicolas Bergeot) with Dr. Yokoyama’s model (NICT/AERI) as base. It shows how a combination of ionospheric disturbances (“scintillation”) with reflected signals from the surroundings can weaken and effectively blacken out radio signals from space- or ground-based transmitters

The main cause of the ionospheric unrest is the presence of equatorial plasma bubbles, i.e., depletions of electron density in the ionosphere. Their number correlates with the solar activity level, and they also are more numerous during the equinoxes (spring and autumn) than during the solstices (summer and winter). They usually form after sunset at the bottom of the F-region (main ionospheric layer), where small low-density irregularities can grow into turbulent bubbles. The bubbles have a typical size of about 100 km and their effects usually end around midnight. They can occur during relatively minor levels of geomagnetic activity, especially during solar cycle maximum. Radio wave propagation can be severely affected in terms of power and intensity as these waves travel through small-scale structures in the ionosphere (i.e., scintillation of radio waves).

At first sight, one would expect relatively strong geomagnetic activity to explain the ionospheric disturbances, but this was not the case on 3–4 March. Quiet to unsettled geomagnetic conditions were observed, with a single active episode during the 21:00–24:00 UT interval on 3 March. According to Kelly and his team, this suppressed the generation of the evening-side depletions and delayed the onset of the ionospheric bubbles until after midnight.

Moreover, analysis of the data from the TIMED satellite led Kelly and his team to conclude that the plasma bubbles affecting the Takur Ghar war theater did not have very steep density gradients, and thus would have resulted only in mild ionospheric disturbances. Normally, this mild ionospheric “scintillation” is not a problem for SATCOM, but the intensity of the already weakened radio signals could have further been reduced by the multiple reflections from the surrounding mountains. Hence they concluded that “… the destructive multipath interference from complex terrain reflections coupled with scintillation could cause a signal blackout….”. The take-home message here is that even mild disturbances, under a set of unfavorable conditions, can create dangerous situations and that users should always be very attentive.

Solar Flares Hampering Hurricane Relief Efforts

To conclude the summary of historical space weather impacts on the military operations and technology, we discuss this last recent case to illustrate that sometimes, it’s just a matter of unfortunate timing.

The 2017 Atlantic hurricane season was one of the deadliest and most catastrophic hurricane seasons in recent history, with a damage total exceeding $200 billion (USD). One of the strongest hurricanes was hurricane Irma, ravaging the Caribbean island chain from the northern Leeward Islands, via Puerto Rico and Cuba to Florida from 6 till 11 September. Coincidentally, from 4 till 11 September, Active Region 2673 (Fig. 7) developed on the solar disk into a complex and very active sunspot group, producing no less than 27 medium and 4 extreme solar flares, including the two strongest flares of the entire solar cycle 24, resp. an X9 on 6 September and an X8 on 10 September (Fig. 8). The numbers of the active regions are determined by the National Oceanic and Atmospheric Administration, NOAA.
Fig. 7

A picture of Active Regions NOAA 2674 and NOAA 2673 (right) on 4 September 2017, as imaged by the Solar Dynamics Observatory (SDO) in white light (left) and in extreme ultraviolet (right). A medium-class flare was in progress in NOAA 2673 at that time. Image courtesy NASA/SDO, AIA and HMI science teams. SDO is the first mission for NASA's Living With a Star (LWS) Program

Fig. 8

The X8 solar flare of 10 September 2017 as measured in soft X-rays by the GOES13 and GOES15 satellites. Flares are categorized as A, B, C, M, or X-class flares. Each class ranges from 1 to 9. Image courtesy NOAA/GOES

These strong flares induced a rapid ionization of the equatorial upper atmosphere, resulting in a disruption of HF communications while emergency workers were struggling to provide critical recovery services to the Caribbean communities (Redmon et al. 2018). The Hurricane Weather Net (HWN) reported that the 6 September solar flare caused a near-total communications blackout for most of the morning and early afternoon. The French Civil Aviation authorities also reported that HF radio contact was lost with an aircraft off the coasts of Brazil and French Guyana for approximately 90 min, triggering an alert phase until a position report was received by New York radio. The 10 September flare also severely disrupted HF communication, with a widespread communication blackout lasting for nearly 3 h, which basically could not have happened at a worse time. The researchers conclude that “… These solar eruptions led to geoeffective space weather impacting radio communications tools used in the management of air traffic as well as emergency-and-disaster assessment and relief, temporarily complicating an already extreme terrestrial weather period.” (Redmon et al. 2018). Further reading on Hurricane Irma is found in chapter XX on Disaster Management.

Space Weather as a Challenge

The Research and Observation Challenge

The above two sections illustrate how the cause-effect chains are coupled over different physical domains from the Sun to the Earth. Many links in these cause-effect chains are poorly understood and space weather, or solar-terrestrial physics, remains thus an active field of research. As compared to meteorological weather, progress in space weather is hampered by the difficulty of obtaining constraining measurements. Measurements of space weather conditions start from observing the Sun, which are necessarily performed from a distance. These “remote sensing observations” (images or timelines) can only be obtained from ground-based telescopes during daytime in wavelengths not hindered by the Earth’s atmosphere (radio and visible parts of the spectrum). Studies of the sources in the solar corona require observations in X-rays or EUV, which can only be observed by satellites outside the Earth’s atmosphere. Even then, only one perspective on the solar globe is obtained and a full 360° view requires several more satellites in deep space observing the Sun from other viewpoints.

The propagation of solar wind plasmas and energetic particles throughout the interplanetary space on their way to the Earth can be confirmed by in situ measurements, but the only stable place between the Sun and the Earth is the Lagrange L1 point where the Sun’s and Earth’s gravitation balance. Unfortunately, following the relative difference in masses, this L1 point is at only 1% of the Earth-Sun distance from the Earth, providing very little warning time for upcoming solar wind disturbances. Further near-Earth in situ space measurements are required to track the state of the magnetosphere and to measure energetic particle fluxes at the top of the atmosphere. The Earth ionosphere is traditionally observed with ionosondes from the ground or through analysis of signals from GPS satellites. Finally, additional observations from the ground are required to measure deflections of the Earth magnetic field during geomagnetic observations. GLEs are confirmed with neutron monitor measurements.

The above list of measurements is only the tip of the iceberg and many additional measurements are possible and probably required to improve scientific understanding. A COSPAR working group has produced a road map for space weather. This report also highlights the importance of another set of measurement data, those of the impacts within the technologies. Measurements of radiation doses at flight altitudes during solar storms or induced currents in the power grid are much less readily available than the corresponding geospatial space weather measurements. Also, in the realm of observed impacts on satellite operations, data are generally not released publicly.

The Societal Challenge

Space weather poses risks to global society, with some regions (e.g., high latitude zones) and some sectors (e.g., those dependent on high precision GNSS) more affected than the others. A proper response to the involved risks will thus differ from region to region and from sector to sector but will require in any case the following elements:
  • Understanding of the vulnerabilities, including impact and likelihood

  • Preparedness through improved engineering of the affected systems

  • Maintaining awareness of the current state of the space environment through observations and analysis in real time

Understanding of the Vulnerabilities

The first step towards a proper handling of the space weather risk within a sector is to have a proper understanding of the (potential) impacts and their likelihood. It is important to note that the exact impact of the space weather phenomena on technological systems goes well beyond space physics and is to a large extent an active separate area of (technological) research. While the physical principles are understood and often historical examples are known to exist (see above), it is much harder to accurately estimate the exact magnitude of the impacts and, more importantly, the associated cost and consequences.

Also, in the case of extreme space weather, one faces the problem of high impact-low probability events which are so rare that proper statistics on impact, cost, and consequences cannot be accumulated (Eastwood et al. 2017). Nevertheless, over the last decades, the understanding of the vulnerabilities has grown substantially in many sectors. Several countries around the world have also explicitly included space weather within their national risk assessments and have accounted for space weather phenomena within their national and sectoral risk management strategies.

Preparedness Through Improved Engineering

When potential impacts are known, there are broadly two venues in order to mitigate the impacts. The first is an engineering solution where the design of the technology is altered such as to become immune or at least less prone to impacts caused by space weather. For example, with sufficient “shielding,” damage to spacecraft electronics by Solar Energetic Particles can be strongly reduced. GNSS positioning errors due to ionospheric variability can to some degree be addressed with dual frequencies or augmentation systems. Such engineering solutions are typically relatively successful for most mundane space weather events but become prohibitively expensive (or even physically impossible) for the most seldom but extreme space weather events.

Maintaining Awareness

When improved engineering or system hardening is not possible, the second strategy is to learn to live with the impacts but reduce their consequences through maintaining active awareness of the current and anticipated space weather conditions, and by actively feeding such information into the operation procedures within each affected sector. As just one example, the International Civil Aviation Organization (ICAO, a specialized agency of the United Nations) has recently identified world space weather information providers that will issue from autumn 2019 onwards so-called advisories to inform aviation actors on the ongoing space weather impacts on HF communication, GNSS positioning, and radiation levels at flight altitudes.

If this second mitigation strategy is followed, one must be aware that the observational challenge highlighted above becomes yet more stringent as the data must be acquired and processed in real time, which is not the case when the observation data are used for research and model development. Given the implied costs, there is a strong case to be made for international cooperation, both for ground-based observations and for observations from satellites. In the case of ground-based observations, there are additional logistical reasons to make observations from multiple sites across the global. Ground-based solar observations require observatories in different time zones and ionosphere and surface geomagnetic field data require spatial resolution.

International Coordination of Space Weather Services

But maintaining awareness of space weather conditions requires more than just having the observational data available. In addition, models to forecast (near) future behavior and human-based assessment of the meaning of the incoming are needed. It also includes deriving more tailored and focused services for specific users based on the observational data, the models, and the forecaster experience.

On a global scale, the International Space Environment Service (ISES, provides daily space weather monitoring and forecasting and brings together space weather monitoring centers from 19 countries around the world. This organization is the main international body devoted to the promotion of such services, facilitating the exchange of data and the exchange between those centers of best practices in providing space weather services. The NOAA Space Weather Prediction Service (SWPC) in the USA is the best-known member. In Europe, space weather services are offered among others through the ISES Regional Warning Centers in the UK (MetOffice), Belgium (Royal Observatory of Belgium), and Poland (Space Research Center). In Europe, the European Space Agency (ESA) has federated many European space weather assets in its Space Situational Awareness (SSA) network with specialized entities (the Expert Service Centers) explicitly focusing on a specific physical domain. The ESA/SSA network concept is still in development and is to be considered preoperational.

The need for globally coordinated observations has recently been channeled through the World Meteorological Organization where a dedicated work stream (Inter-Programme Team on Space Weather Information, Systems and Services) is in the process of including the corresponding observation requirements within the WMO databases regarding observation requirements.

Specific Defense Challenges

Space is sometimes considered the fifth warfare domain. It is at least a critical enabler for land, air, maritime, and cyber operations. Governments and armed forces strongly rely on space-based capabilities and services to fulfill their missions, especially in the frame of expeditionary and intelligence operations. Satellite communications, Global Navigation Satellite Systems (GNSSs), space-based Intelligence, Surveillance and Reconnaissance (ISR), and environmental monitoring are paramount for the success of operations. Therefore, timely reliable space weather information is essential.

The defense sector may be impacted by space weather effects on different levels. At the first level, one might expect military technology to be affected by space weather effects much like the civilian technology as discussed above. Obviously, details of the vulnerabilities of military technology are not readily available to space weather researchers. Here we discuss additional challenges faced by the defense sector beyond the direct impact on technology.

The first specific defense-related challenge is the relation between the needs for space weather services by military users and the capabilities and governance of currently developed space weather service systems. These space weather service systems are currently being developed out from the research community. Consequently, space weather warnings and alerts are typically formulated in scientific jargon describing the state of solar-terrestrial system as a physical system. Such information is not directly actionable by a military user in the field but needs to be translated in terms of potential impact on specific equipment. As this translation requires knowledge of the military equipment in use, it must be done by experts within the defense sector itself. These technical experts need to be trained to understand the scientific jargon and to be able to translate it into actionable information.

In this perspective, we notice huge disparities between the NATO Nations. In fact, only few NATO Nations are quite advanced while the majority has recently envisaged to bridge civil space weather services to the needs by military users. In America, the USAF (US Air Force) already works for years in close collaboration with the Space Weather Prediction Center (NOAA) and fully relies on its experience and knowledge in solar science to produce space weather forecasts. In Europe, the UK Met Office produces space weather forecasts for national civilian and military customers. Also, the Joint Meteorological Group (JMG) relies on the Solar and Terrestrial Center of Excellence (STCE) of Belgium for the provision of space weather data and has developed its own “Space Weather Impact Matrix” depicting the impact of space weather events on Dutch weapon systems.

In NATO, space weather has been recognized a specific matter and belongs to the METOC (Meteorological and Oceanographic) field of expertise. The United States is currently assuming the role of “Assisting Nation” (AN) for space weather. Last year, an ad hoc group has been created to work on standardization and harmonizing in the field of the space weather support to NATO operations.

In Belgium, the Meteo Wing of the Belgian Air Force (BAF) has started a collaboration with the STCE, especially in the field of education and training. What space weather products are concerned, the BAF currently relies on the US being the Space Weather AN. Nonetheless, the BAF strongly envisages extending its collaboration with STCE through the development of specific space weather products to support Belgian military assets and the support of the STCE in distributing and validating space weather advisories for the ICAO.

Another specific defense challenge is to distinguish a space weather impact from sabotage or jamming from the enemy. The same space weather source can affect a wide range of different technologies all over the planet. As we have discussed above, the impact includes reduction in communication possibilities, deterioration of positioning services, and unexpected malfunctioning. Confusion with a coordinated sabotage activity is therefore not excluded. In order to distinguish between a space weather impact or deliberate action, it is necessary to maintain an awareness of the state of space weather.

As mentioned, the – mostly – civilian space weather systems are currently being developed by the research community, although armed forces throughout the world are becoming increasingly active in the field of space weather, for instance, the USA and the UK. This implies that much of the existing space weather services are dependent on research observational infrastructure, both on the ground and in space. This observational infrastructure typically has poor long-term perspectives, very little redundancy and security measures, and even its own functioning might be strongly affected when strong space weather occurs. An independent, fully operational infrastructure for space weather observations is required to maintain serious “space situational awareness.” This would involve many ground-based observatories (per time zone, redundancy for weather conditions) and/or many satellite observatories (remote sensing of the Sun from different perspectives, as well as in situ solar wind observations) and becomes therefore quickly prohibitively expensive for both civilian and military programs.

A final specific challenge for defense is at the extreme side of space weather events. Such extreme events have been observed in the past (e.g. 1859) but not in modern times when society has become fully dependent on power grids and satellite communication. The most extreme space weather events have the potential to damage the major transformators of the power grid worldwide (Schrijver et al. 2014). Such large-scale damage would require months to years for repair resulting in serious problems for basic services such as hospitals and water ans food distribution and might ultimately lead to collapse of the civilian society. The original space weather driver of such unrest will have faded away in at most a few weeks but the military might be called upon to maintain homeland security for much longer.


Space weather as driven by the variable activity of our nearby star, the Sun, has been around since before the dawn of humankind. Our increasing dependence on technology in space and on the ground makes us however increasingly vulnerable to the impact of space weather on technological systems. Whereas – in most sectors – everyday space weather can be handled through improved system hardening, the catastrophic impact that seldom but extreme space weather events can have, cannot be fully excluded. Given its dependence on global communications, accurate GNSS positioning, and satellite operations, also the defense and security sector must take the space weather risks into account. In this chapter, we have listed several historical space weather events that have had surprising impacts on military operations. We advocate that maintaining a “space situational awareness” requires structural communications between space physicists providing real-time analysis of the space phenomena, with technology expert operators that can estimate the impact of these phenomena on the technological systems that the end user cares about.



The contribution by Capt d’Avi Damien Lebrun (Meteo Wing, Be) to section 4.3 is much appreciated.


  1. Bieber JW, Clem J, Evenson P et al (2005) Largest GLE in half a century: neutron monitor observations of the January 20, 2005 event. In: Sripathi Acharya B, Gupta S, Jagadeesan P, Jain A, Karthikeyan S, Morris S, Tonwar S (eds) Proceedings of the 29th international cosmic ray conference, August 3–10, 2005, Pune, India, vol 1. Tata Institute of Fundamental Research, Mumbai, p 237Google Scholar
  2. Cliver EW, Svalgaard L (2004) The 1859 solar-terrestrial disturbance and the current limits of extreme space weather activity. Sol Phys 224(1–2):407–422. Scholar
  3. Cucinotta FA, Hu S, Schwadron NA et al (2010) Space radiation risk limits and Earth-Moon-Mars environmental models. Space Weather 8: S00E09. Scholar
  4. Eastwood JP, Biffis E, Hapgood MA et al (2017) The economic impact of space weather: where do we stand? Risk Anal 37(2):206–218. Scholar
  5. Kelly MA, Comberiate JM, Miller ES et al (2014) Progress toward forecasting of space weather effects on UHF SATCOM after Operation Anaconda. Space Weather 12(10):601–611. Scholar
  6. Knipp DJ, Ramsay AC, Beard ED et al (2016) The May 1967 great storm and radio disruption event: extreme space weather and extraordinary responses. Space Weather 14(9):614–633. Scholar
  7. Knipp DJ, Fraser BJ, Shea MA et al (2018) On the little-known consequences of the 4 August 1972 ultra-fast coronal mass ejecta: facts, commentary, and call to action. Space Weather 16(11):1635–1643. Scholar
  8. Love JJ, Coïsson P (2016) The geomagnetic blitz of September 1941. Eos 97.
  9. Redmon RJ, Seaton DB, Steenburgh R et al (2018) September 2017’s geoeffective space weather and impacts to Caribbean radio communications during hurricane response. Space Weather 16(9):1190–1201. Scholar
  10. Riley P (2012) On the probability of occurrence of extreme space weather events. Space Weather 10(2):S02012. Scholar
  11. Schrijver CJ, Dobbins R, Murtagh W, Petrinec SM (2014) Assessing the impact of space weather on the electric power grid based on insurance claims for industrial electrical equipment. Space Weather 12(7):487–498. Scholar

Further Reading

  1. Large Solar Event Detected During Irma. NCEI/NOAA, 14 September 2017.
  2. Missing British Sub Feared Lost, Safe; Search Called Off. Amsterdam Evening Recorder. LXXVII (158). Amsterdam, New York. 24 February 1956. p 1.
  3. Odenwald S (2015) Solar storms: 2000 years of human calamity. CreateSpace Independent Publishing Platform. ISBN-10: 1505941466Google Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • J. Janssens
    • 1
  • D. Berghmans
    • 1
    Email author
  • P. Vanlommel
    • 1
  • J. Andries
    • 1
  1. 1.STCE-SIDC, Royal Observatory of BelgiumBrusselsBelgium

Section editors and affiliations

  • Maarten Adriaensen
    • 1
  1. 1.European Space AgencyParisFrance

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