- 10 Feb 2022
- 5 min read
Why in News?
Recently, Elon Musk’s Starlink has lost dozens of satellites that were caught in a geomagnetic storm a day after they were launched.
- The satellites were designed to burn up on reentry into the Earth’s atmosphere, and did not create debris in space.
- However, the loss of 40 satellites — most of a launch batch — in a single solar event has been described as “unheard of” and “huge”.
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.
What is a Geomagnetic Storm?
- Solar Storms occur during the release of magnetic energy associated with sunspots (‘dark’ regions on the Sun that are cooler than the surrounding photosphere - the lowest layer of the solar atmosphere), and can last for a few minutes or hours.
- A geomagnetic storm is a major disturbance of Earth's magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth.
- The magnetosphere shields our home planet from harmful solar and cosmic particle radiation, as well as erosion of the atmosphere by the solar wind – the constant flow of charged particles streaming off the Sun.
- These storms result from variations in the solar wind that produce major changes in the currents, plasmas, and fields in Earth’s magnetosphere.
- The solar wind conditions that are effective for creating geomagnetic storms are sustained (for several to many hours) periods of high-speed solar wind, and most importantly, a southward directed solar wind magnetic field (opposite the direction of Earth’s field) at the dayside of the magnetosphere.
- This condition is effective for transferring energy from the solar wind into Earth’s magnetosphere.
- The largest storms that result from these conditions are associated with solar Coronal Mass Ejections (CMEs) where a billion tons or so of plasma from the sun, with its embedded magnetic field, arrives at Earth.
- CMEs are large ejections of plasma and magnetic fields that originate from the Sun's corona (outermost layer).
How does it 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.