Geomagnetic Storm Effects

In our earlier post on “Where does Space Radiation come from?”, we briefly mentioned that one of the sources of space radiation are solar particles that originate from the sun. These two rare events, solar coronal mass ejections (CME) and solar flares, generate large amounts of solar particles and geomagnetic storms at Earth with energies orders of magnitude greater than usual and that can affect satellites. 

With the recent events of geomagnetic storms hitting Earth’s magnetosphere, it is a good time to explain in this post what a geomagnetic storm is and how it can affect space electronics and satellites. 

What is a geomagnetic storm?

Geomagnetic storms are temporary disturbances in Earth’s magnetosphere caused by solar winds. 

The Sun’s surface contains huge amounts of plasma (electrically charged protons and electrons) which is constantly moving, resulting in stretching, twisting and crossing of the magnetic field. This magnetic field is in charge of the flow of particles that are responsible for the activity on the Sun’s surface, called solar activity. 

Solar activity includes solar flares (tidal waves of high-energy radiation), sunspots (temporary regions of strong magnetic fields), solar winds and coronal mass ejections. The Sun’s magnetic field powers the solar activity levels and can be quite variable in intensity.  Every 11 years, the Sun’s poles flip; north becomes south and south becomes north, so every 22 years the poles return to the initial position where they started the solar cycle. When the sun is approaching solar maximum, that is when the magnetic field is strongest, solar flares and CMEs are more common. The opposite occurs when the Sun reaches solar minimum.

Image 1. Twenty-five images (one image per year) of the Sun captured by SOHO satellite

The magnetic field reserves massive amounts of energy that escapes to the solar system. It transfers with a constant trickle of solar plasma like a light rain, and it is commonly known as the solar wind. When it exceeds certain levels, it leaks out solar storms. Solar storms come in many types depending on their intensity and can be solar fares, solar winds or CMEs. Luckily, these solar storm particles cannot easily enter the Earth’s magnetic field. When the particles hit the magnetic field, they are deflected, thus confining the magnetic field on the side towards the Sun and stretching it out on the opposite side. The formation of this magnetic field line confinement is called the magnetosphere. 

This charged plasma from a CME that is pivoted away by the Earth’s magnetic field redirects the energy storm to the North and South Poles, where energetic particles penetrate the atmosphere causing it to glow and create auroras (northern and southern lights).

Image 2. The Sun-Earth connection

However, sometimes the Sun generates solar superstorms. A superstorm is a CME and can contain billions of tons of magnetic plasma that travels the 150 million kilometre distance between the Sun and Earth in a day or more. Once it arrives, it causes a blast shock that violently contracts the Earth’s magnetic field and transfers energy into the magnetosphere. During the event, the magnetic field of the CME aligns to the Earth’s magnetic field, the two magnetic fields become one moving cloud of charged particles. When this cloud passes over Earth, it stretches the Earth’s magnetic field into a long tail. Ultimately, when the stored energy in the tail reaches a critical level, it breaks and explosively releases some of its energy towards Earth. This is when a geomagnetic storm begins.

One of the biggest geomagnetic storms ever recorded was the Carrington event that took place in September 1859. It is believed that this storm was a result of a CME that travelled 18 hours from the Sun to the Earth. During the Carrington Event, auroras were observed all over the world, instead of just high latitudes. It also caused disruption to the majority of pagers in the USA. Telegraph lines were electrified, people were being zapped by operators.

Despite that, even smaller storms can damage satellites, affect radio communications or be dangerous to astronauts. 

Image 3. Sun-Earth interactions

So what does a geomagnetic storm do to the satellites?

A solar superstorm causes massive increases in radiation particle fluxes observed by satellites. This can have many effects on the satellites’ systems and lifetime, but the ultimate damages will depend on the satellite’s orbit and shielding. As the altitude increases, the shielding against geomagnetic storms decreases and when the events become extreme, the satellite’s surface materials degrade considerably at all orbits (GEO, MEO and polar-orbiting satellites in LEO at high latitudes). 

For example, Galaxy IV was in GEO orbit which was 35,000 km above the Earth. In May 1998, the telecommunications satellite suffered an electrical short circuit (ESD), causing it to spin out of control and eventually the satellite was lost. This consequently caused disruption to more than 80% of the pagers in the USA.

Effects of Space Weather Events

Extreme weather events, such as geomagnetic storms, can cause multiple damages to satellites and space electronics.

  • Navigation Systems (GPS) errors
    The effects on navigation systems (GPS) is probably the most crucial one because most missions rely on them. The ionosphere between the satellites increases as a result of the geomagnetic storm’s currents and energy. This causes GPS systems to malfunction and generates position calculations errors up to even 100 m, while the average accuracy of a functioning GPS system is ≤ 7.8 m. Sometimes the navigation systems will completely lose their signal.

  • Satellite drag
    Another significant effect from the solar activity is the satellite drag. During the Sun’s higher activity levels, the drag force on satellites increases and changes their orbits. This happens due to the fact that the increased ion flux originating from the Sun displaces low-density layers of the air from LEO to higher position and LEO is substituted by the higher density layers that were at lower latitudes before. Consequently, the satellite will encounter a stronger drag force as it crosses through the higher density and can either fall to Earth or collide with space orbiting debris resulting in a total loss of the satellite. A good example of that was Skylab which re-entered the atmosphere several years earlier than planned.

  • Solar cell degradation
    During the Sun’s extreme activity, there has been observed degradation in the power-generating capability of satellite solar panels, resulting in the reduction of their lifetime by several years.

  • Star Sensor Units malfunction
    When the Solar storm’s charged particles hit the integrated circuits (ICs), they create electrons that charge up the pixels causing a mix-up to the altitude control.

  • Effects on Military Systems
    Geomagnetic storms also affect military systems. There have been noted multiple errors in tracking missiles and GPS, making it difficult to stop a hostile missile. Satellite communications can also be off for up to several hours.
Image 4. Heliophysics System Observatory (HSO)

Examples of the satellite failures and losses caused by extreme solar events

DateSolar EventSatelliteOrbitPossible CauseResults/Effects
11 July 1979Solar stormSkylabLEOIncreased DragTotal loss
October 1989CMETDRS-1GEOSEE (SEU)249 SEU anomalies
20 January 1994Solar windAnik 1&2, Intelsat KGEOSEU/ESDTemporary outage
8 January 1997Solar StormGOES 8GEOESDMalfunction for 37 h
11 January 1997Solar stormTelstar 401GEODragTotal loss
19 May 1998Solar windGalaxy 4GEOESDTotal loss
14 July 2000CMEASCALEOIncreased DragBatteries discharge-Total loss
14 July 2000CMEACE, WINDHaloSEETemporary problems
14 July 2000CMETRACESSOSEETemporary problems
14 July 2000CMEYOHKOHLEOSEETemporary problems
14 July 2000CMESOHOHaloDDD2% drop in solar array efficiency-Temporary problems
24 October 2003CMEADEOS-2LEOESDSevere power failure-Total loss
14 January 2005Solar stormIntelsat 804GEOESDTotal loss
5 April 2010Solar windGalaxy 15GEOESDOutage (8 months)
7 March 2012CMESkyTerra 1GEOSEE (SEU)Outage (1 day)
Understanding these unique system failures and the ability to develop robust mitigation strategies is critical for space missions.

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