Space Weather

There are three types of space-weather storms: geomagnetic storms, radiation storms and radio blackouts. ^1,2 There have been a considerable number of large solar storms since they were first observed in 1859—the Carrington event. In 2012, a large Carrington event occurred on the opposite side of the Sun, producing a very large solar flare—had it occurred a week earlier, the Sun would have been facing the Earth, with an effect that would have crippled satellite communications, GNSS, and severely damaged the power grid. ³ Such a storm occurring today would cause widespread damage, with a likely impact exceeding US$2 trillion (20 times the costs of Hurricane Katrina) in just the continental US electricity distribution systems alone. ^4,5,6 Smaller events occur more frequently, such as that which affected the Hydro-Quebec power grid on 13–14 March 1989 at a cost of some C$13.2 billion. ⁷ Although such events have been rare, it is estimated that there is a 12 per cent chance that such a storm will impact Earth in the next ten years ⁸ or, in terms of time, historical records suggest a return period of 50 years for a Quebec-level storm and 150 years for a Carrington event. ⁹ On 26 March 2019, the US issued the Executive Order on Coordinating National Resilience to Electromagnetic Pulses which was subsequently incorporated into the FY2020 National Defense Authorization Act, giving it the force of law.

The catastrophic effects of an extreme space-weather event are largely due to the widespread loss of electric power. If power remains available, there will be intermittent loss of HF-based systems, minimal impact to radio-relay and cellular services, interference or intermittent loss of GNSS navigation signals, and no significant impact on electronic devices. ¹⁰ However, severe geomagnetic storms can affect satellite attitude control systems, and solar radiation storms can render satellite systems useless—examples include the Anik satellite in the late 1980s, AT&T’s Telstar 401 satellite in January 1997, two Telesat Canada Anik (E1 and E2) satellites in January 1994, and Intelsat 511 in October 1995. ¹¹

Geomagnetic storms can also heat the atmosphere increasing drag on satellites in LEO and can cause uncontrolled re-entry ¹². For example, 49 Starlink satellites were launched aboard a SpaceX Falcon 9 rocket on 3 February 2022. However, shortly after the launch, a minor geomagnetic storm disrupted the satellites’ orbits. The storm, which was caused by a coronal mass ejection (CME) from the Sun, created increased drag in the Earth’s upper atmosphere. This increased drag significantly slowed down the satellites and caused them to deorbit. Many of these satellites re-entered Earth’s atmosphere and burned up, falling into the Caribbean Sea. While minor losses had been expected and only two Starlink satellites re-entered in 2020, by 2024 that figure had soared to 316.