New balloon-mounted space radiation probes developed by the Surrey Space Center at the University of Surrey have captured their first measurements of a major solar storm, confirming the research team's model, which indicates the flare caused the highest levels of radiation at aviation altitude in almost two decades.

The solar flare—classified as an X5 event—triggered a rare Ground Level Enhancement (GLE) on 11 November 2025, in which solar energetic particles penetrated deep into Earth's atmosphere and caused a radiation surge that was detectable even at ground level. Within an hour, the UK Met Office and their counterparts at KNMI in the Netherlands began launching a sequence of weather observation balloons equipped with Surrey's sensors to measure the storm in real time—right up to commercial aircraft altitudes and into regions used by business jets and supersonic transport.

Radiation levels and aviation impact
Early analysis shows that radiation levels at 40,000 feet rose to their highest since 2006, reaching almost ten times normal background levels for a short period. Although this event did not pose any immediate health concern, larger storms in future could be more worrying, not least because they have the potential to disturb on-board aircraft electronic systems. During the storm's peak, the team estimate that single-event upsets—bit-flips in onboard computer memory caused by energetic particles—could have reached around 60 errors per hour per gigabyte.

Professor Clive Dyer, an expert in space weather at Surrey Space Center, University of Surrey, said, "This was the strongest Ground Level Event we've seen since December 2006. Neutron monitors around the world measured significant increases and, in conjunction with newly installed UK monitors at Lerwick, Guildford and Camborne, these will enable us to map the footprint of the event across the globe.

"Our sensors have given the clearest picture yet of how rapidly conditions can change at aviation altitudes. We know from historical observations that significantly bigger events are possible, and we need to be ready."