Geomagnetic Storm

Context:

Recently, Elon Musk’s Starlink has lost dozens of satellites that were caught in a geomagnetic storm a day after they were launched.

What is geomagnetic storming?

• A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth’s magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earth’s magnetic field.
• The disturbance that drives the magnetic storm may be a solar coronal mass ejection (CME) or (much less severely) a co-rotating interaction region (CIR), a high-speed stream of solar wind originating from a coronal hole.
• The frequency of geomagnetic storms increases and decreases with the sunspot cycle.
• During solar maximum, geomagnetic storms occur more often, with the majority driven by CMEs.
• The increase in the solar wind pressure initially compresses the magnetosphere.
• The solar wind’s magnetic field interacts with the Earth’s magnetic field and transfers an increased energy into the magnetosphere.
• Both interactions cause an increase in plasma movement through the magnetosphere (driven by increased electric fields inside the magnetosphere) and an increase in electric current in the magnetosphere and ionosphere.
• During the main phase of a geomagnetic storm, electric current in the magnetosphere creates a magnetic force that pushes out the boundary between the magnetosphere and the solar wind.
• Several space weather phenomena tend to be associated with or are caused by a geomagnetic storm.
• These include solar energetic particle (SEP) events, geomagnetically induced currents (GIC), ionospheric disturbances that cause radio and radar scintillation, disruption of navigation by magnetic compass and auroral displays at much lower latitudes than normal.
• The largest recorded geomagnetic storm, the Carrington Event in September 1859, took down parts of the recently created US telegraph network, starting fires and shocking some telegraph operators.
• In 1989, a geomagnetic storm energized ground induced currents that disrupted electric power distribution throughout most of Quebec and caused aurorae as far south as Texas

How does Geomagnetic Storm Affect Earth?

• Can Impact Space Weather:
  • Not all solar flares reach Earth, but solar flares/storms, Solar Energetic Particles (SEPs), high-speed solar winds, and Coronal Mass Ejections (CMEs) that come close can impact space weather in near-Earth space and the upper atmosphere.
• Can Hit Operations of Space-Dependent Services:
  • Solar storms can hit operations of space-dependent services like Global Positioning Systems (GPS), radio, and satellite communications. Aircraft flights, power grids, and space exploration programmes are vulnerable.
• Can Potentially Create Disturbances in the Magnetosphere:
  • Coronal Mass Ejections (CMEs) with ejectiles loaded with matter travelling at millions of miles an hour, can potentially create disturbances in the magnetosphere, the protective shield surrounding the Earth.
  • Astronauts on spacewalks face health risks from possible exposure to solar radiation outside the Earth’s protective atmosphere.

How are Solar Storms Predicted?

• Solar physicists and other scientists use computer models to predict solar storms and solar activities in general.
  • Current models are capable of predicting a storm’s time of arrival and its speed.
  • But the storm’s structure or orientation still cannot be predicted.
• Certain orientations of the magnetic field can produce a more intense response from the magnetosphere, and trigger more intense magnetic storms.
  • With the increasing global dependence on satellites for almost every activity, there is a need for better space weather forecasts and more effective ways to protect satellites.

What is Starlink?

• Starlink is a SpaceX project to build a broadband network with a cluster of orbiting spacecraft that could eventually number thousands.
• The Starlink satellites carry Hall thrusters, which use electricity and krypton gas to generate an impulse, to manoeuvre in orbit, maintain altitude and guide the spacecraft back into the atmosphere at the end of their mission.
• The Starlink network is one of several ongoing efforts to start beaming data signals from space.

Source: Indian Express

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