Research*eu Results Magazine May 2017 [antikvár]

SPECIAL FEATURE EXTREME SPACE WEATHER LET'S GET READY NOVEL PREDICTION TOOLS FOR SEP EVENTS Advancing our capacity to predict 'Solar energetic particle' (SEP) events is essential to the smooth running of human spaceflights beyond Earth. New space weather prediction tools developed under the HESPERIA project have reached a milestone, notably by enabling earlier prediction of 'Ground level enhancement' (GLE) events — which pose severe radiation hazards to astronauts and tend to disrupt airline communication. ESPERIA (High Energy Solar Particle Events foiiecast-— Ing and Analysis) had three core objectives: building new forecasting tools based on empirical forecasting models UMA5EP and REleASE; advancing scientific understanding of the physical mechanisms leading to SEPs; and exploring the possibility of Incorporating its results into future space weather services. 'Forecasting solar particle radiation storms, the so-called SEP events, is of potential Interest for spacecraft and launching operations, and for the assessment of radio wave propagation conditions in the polar ionosphere of the Earth,' Dr Olga Malandraki, Senior researcher at the National Observatory of Athens and coordinator of the project, points out Better SEP predictions would not only make future space exploration missions safer, but also help airlines avoid exposure to resulting radiations. Before HESPERIA was kicked off In 2015, the communit/ was facing the need for new services able to predict solar particle storms with a significantly higher precision. The project successfully fulfils this need with SEP forecasting tools providing accurate real-time forecasting of large SEP events in the energy range of 30-50 ivleV and above 500 MeV protons. To make this possible, Dr Malandrakl's team built Its novel tools — HESPERIA UMASEP-SOO and HESPERIA REleASE — based respectively on empirical forecasting models U(>/IASEP and REleASE, whose high performance Is widely acknowledged by the scientific community. The first model uses early signatures In solar activity to predict SEPs, whilst the second focuses on faster particles which tend to reach spacecraft earlier than forecasted. HESPERIA Ui«1ASEP-500 makes real-time predictions of the occurrence of GLE events from the analysis of soft X-ray and differential proton flux measured by the GOES satellite network 'The main Innovation Is that our tool utilises spacecraft proton data for the SEP forecasting, which proved to allow the tool to make successful GLE predictions earlier compared to existing predicting models based on ground-based neutron monitor measurements,' says Dr Malandraki. HESPERIA REleASE, on the other hand, lowers false alarm rates and Increases probabilities of detection of energetic protons between 30 and 50 luleV when compared to existing tools. It does so by using near-relativistic and relativistic electrons from the ACE and SOHO spacecraft as precursors. The two tools are available from the project's website. Understanding SEP-related mechanisms better Beyond Its forecasting tools, HESPERIA also brings about important Insights into the physical mechanisms resulting in SEPs, most notably the frequent occurrence and sometimes long duration of y-ray events at photon energies above 100 luieV, as well as the relationship between 'interplanetary' (IP) proton occurrence on Earth and protons on the Sun. 'An important finding was that the long-duration y-ray events are accompanied by long-duration soft X-ray burst and the formation of coronal loops in the aftermath of "coronal mass ejections" (CMEs),' Dr Malandraki says of the project's analysis of y-ray events above 100 MeV, which currently pose a challenge to our understanding of particle acceleration processes on the Sun leading to SEP occurrence at 1AU. 'Also, the long-duration y-ray events have been found to be