Since the dawn of the ‘Space Age’ in the late 1950s, we have become increasingly susceptible to space weather as we have grown more reliant on electrical grids, satellite navigation, space infrastructure, and radio and wireless communications. But while there have been a number of severe space weather events during this period, it is generally considered that modern technology is yet to experience a ‘once-in-a-century’ or more extreme space weather event.
In September 1859 a massive solar flare released billions of tons of matter towards Earth, impacting some seventeen hours later and inducing electrical currents in the telegraph system causing it to catch fire. What if an event of this magnitude were to impact today’s modern interconnected world?
What is Space Weather?
The term ‘space weather’ refers to events beyond the Earth’s atmosphere that impact upon our technology and the near-Earth space environment. The primary source of space weather is the sun, with the greatest disturbances usually caused by solar flares and subsequent geomagnetic storms.
Solar flare eruptions are sometimes associated with:
- increased x-ray and radio emissions that reach Earth within eight minutes (sometimes up into the ultra-high frequency (UHF) band);
- an increase in the flux of energetic protons typically reaching Earth in 30 minutes to six hours (referred to as solar energetic protons, solar energetic particles or SEPs) and
- an increase in the mass and velocity of solar wind particles and magnetic field strength reaching Earth typically within half a day to three days (collectively termed a coronal mass ejection or CME). On reaching Earth, a CME may cause geomagnetic and ionospheric storms.
Other solar features such as coronal holes and disappearing solar filaments can also have impacts on the near-Earth space environment—although these are generally not as significant as the space weather storms generated by large solar flares.
All these phenomena can impact on technologies in the near-Earth space environment as detailed below. In summary, space weather can:
- jam radio waves, affecting telecommunications and radar systems;
- damage satellites, or render them non-functional as operators ‘hibernate’ them to protect them from harm;
- overload power circuits, causing a risk to electricity supply and infrastructure;
- make global navigation satellite systems (GNSS) signals unreliable; and
- increase harmful solar radiation, with possible risks to health at aviation altitudes.
Satellites
The near-Earth space environment contains energetic particles which are hazardous to satellite infrastructure. Space weather events can lead to significant increases in the particle levels, increasing the risk of ‘dielectric discharge’ and ‘single-event upset’ events on satellites, causing loss of data and/or control. Some operators may place satellites into ‘safe mode’ during intense particle radiation events to mitigate damage. In addition, during intense geomagnetic and ionospheric storms the upper atmosphere is heated and expands, leading to increased drag on low-orbit satellites. Further, satellite signals can experience ‘scintillation’ effects (a rapid fluctuation in the signal strength due to ionospheric irregularities) in particular regions and short duration (minutes) interference during intense solar radio emissions.
Satellite Navigation Systems
One of the largest sources of error in global positioning systems (GPS) or precision navigation and timing systems (PNT) signals is due to the passage of the satellite signal through the relatively dense electron environment of the upper atmosphere. These errors are typically compensated for by using correction models. During ionospheric storms or periods where the ionosphere deviates from normal conditions the models may be inadequate and lead to errors. Precision navigation systems that autocorrect for the ionosphere, such as differential GPS, may be susceptible to errors during severe ionospheric storms. GPS may also be susceptible to interference from solar radio bursts in the UHF range, leading to significant loss of satellite availability for tens of minutes (in severe cases).
High-Frequency Communications
Background radiation produced by the sun in the extreme ultraviolet (EUV) and X-ray range is typically absorbed at altitudes above 90 km, in a region known as the ionosphere. This region supports the High-Frequency (HF) radio communication used by defence, aviation and emergency service sectors. Emissions associated with solar flares and SEP events produce ionisation of the Earth’s upper atmosphere at lower altitudes, which causes increased absorption of HF radio communications, leading to radio ‘blackouts’ or loss of HF communications.
VHF/UHF Systems
Solar radio bursts have been shown to interfere with very/ultra-high frequency (VHF/UHF) signals when base station antennae are aligned in a particular direction at a particular time of day and coincide with an intense solar radio burst. In severe cases, the interference may last for tens of minutes.
Power and Energy Systems
During geomagnetic storms there are relatively short-term variations of the Earth’s magnetic field. These result in an electric field in the Earth’s surface which can drive currents (referred to as geomagnetically induced currents or GICs) through long grounded conductors such as power grids and pipeline networks. The GICs can flow through high-voltage power transformers and cause them to operate outside their optimum performance range, resulting in overheating and possible failure, system harmonics, unwanted power consumption and instability in the power system. Under extreme conditions, power restrictions or outages may occur. GICs flowing in pipelines cause an increased rate of corrosion, reducing asset lifespan.
Extreme Space Weather Events
The benchmark typically used for an extreme space weather event is referred to as the ‘Carrington Event’, named after the English astronomer Richard Carrington, who first observed and reported the extreme solar flare event of 1–2 September 1859. The geomagnetic storm that followed has been estimated to be a number of times more intense, on the geomagnetic storm-time index, than any other such event in the Space Age.
The impacts of the Carrington Event have been widely documented and analysed. It was said that this ‘solar superstorm’ produced auroras so powerful that people in the northeast United States could read newspapers by their light. Across the entire northern hemisphere, massive electrical currents surged through telegraph lines and caused sparks to leap within the telegraph system. Even when telegraph operators disconnected the batteries powering the lines, aurora-induced currents in the wires allowed messages to be transmitted.
There has been a number of smaller solar storms of note in more recent times. In 1989, the Canadian province of Quebec suffered a nine-hour blackout due to a solar storm that knocked out power to six million customers in less than two minutes. In late October 2003, a major geomagnetic storm, often referred to as the Halloween storms, led to the damage of 14 large electrical transformers in South Africa. The Halloween storms also caused large ionospheric gradients that rendered the Wide Area Augmentation System in the US used for precision landing approaches by aviation unavailable for 11 hours. Numerous satellite anomalies and impacts to satellite operations were also reported during these storms. During a more modest space weather event of the 8th September 2017, X-rays produced by the solar flare caused HF radio blackouts that disrupted emergency communications vital to recovery efforts following Hurricane Irma.
It is considered that during an extreme space weather event scenario:
- partial loss of satellite infrastructure and disruption to satellite communications is likely;
- significantly degraded and unreliable GNSS navigation and timing systems is likely;
- intermittent disruptions to VHF/UHF telecommunications systems is possible;
- νoss of HF communications systems is highly likely, and
- power supply instability and transformer damage is possible—while widespread loss of power is unlikely, prolonged outages to major metropolitan areas could occur.
Recent studies by Jonas et al. (2018, doi: 10.1111/risa.12981) have suggested the probabilities of occurrence for a space weather storm within the range of estimated Carrington event magnitudes are approximately 0.7-3% within the next 10 years and 7-35% within the next 100 years.
Preparing for a ‘perfect space storm’
Over recent years there have been increasing efforts to understand the possible risks to society and critical infrastructure posed by such low-frequency, high-impact events and how best to mitigate them. Extreme space weather has been formally recognised in the US and UK as a threat to modern society through its reliance on a variety of vulnerable technologies and critical infrastructures such as power grids, precision navigation and timing systems, satellite infrastructure, and communications systems. Recently, the United States released the United States National Space Weather Strategy and Action Plan (2015, 2019), and United States Presidential Executive Orders (2016, 2019) were issued to coordinate efforts for space weather events through a cross-agency response. In the United Kingdom, socioeconomic and other impact studies (Cannon, 2013) resulted in space weather being entered into the U.K. Risk Register of Civil Emergencies (Cabinet Office, 2017), with subsequent development of space weather services and related mitigation activities.
In 2019, the Canadian Space Agency completed a risk assessment into the impacts of space weather on Canada’s critical infrastructure.
For the past several years the International Civil Aviation Organisation (ICAO), in collaboration with the World Meteorological Organisation and space weather service providers, has been working on developing a global service that provides space weather advisories specifically for aviation. The first iteration utilises three global centres to fulfil the ICAO requirements (US, PECASUS – a European consortium, and ACFJ – a consortium involving Australia, France, Canada and Japan) with the service going live November 2019.
The United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS) has recognised that space weather is a global challenge and at the 55th session of the Scientific and Technical Subcommittee of COPUOS in 2018, the Working Group on the Long-term Sustainability of Outer Space Activities agreed that consensus had been reached on guidelines relating to space activities (A/AC.105/L.315) in which the following recommendation relating to space weather is made under Guideline 17:
“17.7 States should undertake an assessment of the risk and socioeconomic impacts of adverse space weather effects on the technological systems in their respective countries.”
Within Australia, the Bureau of Meteorology, along with other government agencies has been raising awareness of the potential impacts of space weather to the operations of critical infrastructure. National and state level workshops and training exercises have been conducted to test the response procedures of operators and disaster management organisations during an extreme space weather event scenario.
Space weather information
The Australian Bureau of Meteorology provides space weather information and warning services to the Australian region and beyond. These are available 24/7 on its Space Weather Services website (www.sws.bom.gov.au). It is also working closely with industry sectors with operations exposed to space-weather risk—such as aviation, energy, defence and telecommunications—moving towards tailoring forecasts and warnings to their specific needs. After several years of investigation and collaboration, the Australian Energy Market Operator implemented procedures for the management of severe space weather geomagnetic storms. An integral part of these procedures is the issuing of a severe space weather event warning by the Bureau, which gives them up to 24 hours’ notice to enact their plans.
The Bureau’s severe space weather advisory service focuses on forecasting and monitoring severe-to-extreme events that could be of threat to critical infrastructure. Like the Bureau’s cyclone and other severe weather warning services, graded advisory notifications (e.g. ‘Event watch’, ‘Event in progress’) are issued when an event occurs on the sun with characteristics typical of previous events that have resulted in severe space weather. Details of this service can be found at www.ips.gov.au/mailman/listinfo/ips-esws-general or under the Warnings section at www.sws.bom.gov.au/Products_and_Services/4/1
For more information, go to sws.bom.gov.au
References
- Cabinet Office. (2017). National Risk Register of Civil Emergencies – 2017 Edition. London, (https://www.gov.uk/government/publications/national-risk-register-of-civil-emergencies-2017-edition)
- Cannon, P. (2013), Extreme space weather: impacts on engineered systems and infrastructure, Royal Academy of Engineering, London.
- United States National Space Weather Strategy and Action Plan (2015), https://www.sworm.gov/publications/2015/swap_final__20151028.pdf
- United States National Space Weather Strategy and Action Plan (2019), https://www.whitehouse.gov/wp-content/uploads/2019/03/National-Space-Weather-Strategy-and-Action-Plan-2019.pdf
- United States Presidential Executive Order (2016), Coordinating Efforts to Prepare the Nation for Space Weather Events, https://obamawhitehouse.archives.gov/the-press-office/2016/10/13/executive-order-coordinating-efforts-prepare-nation-space-weather-events
- United States Presidential Executive Order (2019), Coordinating Efforts to Prepare the Nation for Space Weather Events, https://www.whitehouse.gov/presidential-actions/executive-order-coordinating-national-resilience-electromagnetic-pulses/
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