What Space Weather Is and How It Threatens Indian Infrastructure

On 10 November 2003, grid operators across Sweden watched voltage collapse in under a minute. The culprit was not a failed transformer or a storm. It was a geomagnetic disturbance triggered by a solar eruption 150 million kilometres away. India did not have that kind of documented blackout that year, but the physics that caused Sweden's failure applies equally to every high-voltage transmission line running across the subcontinent.

The Sun constantly sheds charged particles in a stream called the solar wind. Most of the time this wind is steady and Earth's magnetic field deflects it. The trouble begins when the Sun does something violent: a solar flare, a coronal mass ejection, or a burst of high-energy protons from a solar energetic particle event.

A coronal mass ejection, or CME, is a cloud of magnetised plasma that can weigh several billion tonnes and travel between 500 and 3000 kilometres per second. When it reaches Earth, it compresses the magnetosphere on the dayside and stretches it on the nightside. That compression drives electric currents in the ionosphere, and those currents induce voltages in anything long and conductive on the ground, power lines, railway tracks, oil pipelines.

The scale of the disturbance is measured on the Kp index, a number from 0 to 9. A Kp of 5 or above is classified as a geomagnetic storm. The Carrington Event of 1859, the most powerful geomagnetic storm in recorded history, would sit near the top of that scale. Telegraph wires caught fire. Operators reported receiving messages with the main battery disconnected, driven entirely by induced current from the storm itself.

The specific danger to power infrastructure is called a geomagnetically induced current, or GIC. When the magnetic field changes rapidly, Faraday's law is not optional: a voltage is induced in every conductor that cuts across those changing field lines. Long transmission lines act as antennas. The induced current is quasi-DC, meaning it flows in one direction rather than alternating, and that is exactly the kind of current that saturates the iron cores of high-voltage transformers.

A saturated transformer draws reactive power, overheats, and can fail permanently. Replacing a large extra-high-voltage transformer is not a matter of days. Lead times run to twelve to eighteen months for custom units. India's northern and northeastern grid corridors, which carry power across long distances through regions with varied ground conductivity, are the segments most exposed to this effect.

The Indian power grid has grown substantially since the 2003 event. The inter-regional transmission network now spans hundreds of thousands of kilometres of high-voltage lines. POSOCO, the Power System Operation Corporation, monitors grid stability in real time, but GIC monitoring, the specific instrumentation that tracks geomagnetically induced currents at transformer neutrals, remains sparse compared to what operates in Canada or Scandinavia, both of which sit at higher geomagnetic latitudes and learned this lesson earlier.

India's civil aviation system, its merchant shipping routes, and the precision agriculture programmes now running across several states all depend on GPS or its Indian equivalent, NavIC. Space weather attacks these systems through a different mechanism: ionospheric scintillation.

The ionosphere is the layer of the upper atmosphere where solar radiation knocks electrons loose from atoms, creating a plasma. GPS signals pass through this layer on their way from satellite to receiver. During a geomagnetic storm, the ionosphere becomes turbulent. Signal paths bend unpredictably, and receivers lose lock, sometimes for minutes, sometimes longer.

India sits near the magnetic equator, and the equatorial ionosphere is particularly prone to a phenomenon called equatorial plasma bubbles, which form after sunset and intensify during geomagnetically disturbed periods. The Indian Space Research Organisation has operated a network of ionospheric monitoring stations for years, and ISRO's Space Weather Monitoring Centre in Ahmedabad tracks these conditions. NavIC's design accounts for some of this, but no satellite navigation system is immune to a severe storm. An aircraft on approach to an Indian airport using GPS-based landing guidance during a Kp-8 storm is navigating with degraded information.

Low Earth orbit is not outside Earth's magnetic protection, but it is not fully inside it either. The South Atlantic Anomaly, a region where the inner Van Allen radiation belt dips closest to Earth's surface, passes over parts of the South Atlantic and affects satellites on every orbit that crosses it. Indian remote sensing satellites, communication satellites in the INSAT series, and the upcoming Gaganyaan crewed mission all operate in or through radiation environments that intensify during solar energetic particle events.

For uncrewed satellites, the main risks are single-event upsets, bit flips in memory caused by a high-energy particle, and long-term degradation of solar panels and electronics. ISRO engineers design for these effects using radiation-hardened components and shielding, but a severe solar particle event can exceed design margins.

For Gaganyaan, the stakes are higher. The crew inside the spacecraft receives a radiation dose that accumulates over the mission. ISRO's mission planning will account for solar activity forecasts, and the spacecraft includes shielding, but a major solar particle event during an extravehicular activity, a spacewalk, is the scenario mission controllers most want to avoid. NASA's Artemis programme and ESA both maintain real-time particle radiation forecasts for exactly this reason. ISRO's coordination with NOAA's Space Weather Prediction Center and with the Indian Institute of Geomagnetism gives mission planners the data feed they need.

India's international internet traffic runs largely through undersea fibre-optic cables. These cables carry repeaters, amplifiers spaced every 50 to 150 kilometres along the seafloor, that require a DC power feed running the length of the cable from shore terminals. That power feed is a long conductor in contact with seawater, which is itself conductive. During a major geomagnetic storm, the voltage induced along that conductor can exceed the tolerance of the repeater electronics. The 1989 Quebec blackout is the most cited power-grid failure from space weather, but a 1989 storm also damaged the repeaters on the TAT-8 transatlantic cable.

Indian Railways operates one of the world's largest rail networks. Long steel rails are conductors. Signalling systems that use track circuits, which detect a train's presence by measuring electrical continuity in the rail, can be confused by GICs flowing through the same steel. A false clear signal is not a theoretical concern; it is the kind of failure that rail safety engineers in geomagnetically active regions have documented and designed around. The extent to which Indian Railways' signalling infrastructure has been assessed for this specific vulnerability is not publicly documented in detail.

The thread connecting power grids, GPS, satellites, cables, and railways is the same: each system uses something long, conductive, or signal-dependent in an environment that space weather can reach. The Sun does not distinguish between a Swedish grid and an Indian one. The difference, so far, has been timing and the absence of a storm severe enough to make the exposure visible.