Development and Deployment of the Smart Active Ionising Radiation at Altitude (SAIRA) Instruments for Space Weather Applications

Abstract

This paper introduces the latest generation of airborne ionising radiation monitors, developed at the Surrey Space Centre (SSC) as part of the United Kingdom's (UK's) Space Weather Instrumentation, Measurement, Modeling and Risk (SWIMMR) program. These Smart Active Ionising Radiation at Altitude (SAIRA) instruments are deployed on commercial aircraft and weather balloons to measure atmospheric radiation during both quiet and enhanced space weather conditions, such as Ground Level Enhancements (GLEs). The instruments use silicon photodiodes to record linear energy transfer across 16 channels, enabling accurate determination of absorbed dose, with conversion processes for ambient dose equivalent and particle fluxes. Two configurations have been developed: a portable aircraft unit and a balloon unit compatible with Vaisala RS41 radiosondes. Calibration and validation have been performed using laboratory sources, neutron facilities, and in‐flight measurements. Initial operational data from UK airlines demonstrate reliable performance and coverage, with further deployments planned. The SAIRA instruments provide critical data for validating radiation models with future developments aimed at expanding capabilities and wider availability.