Key issues in Space weather

STRUCTURE 1.What is space weather 2.Issues for a.Upper atmosphere effects b.Charged particle environments c.Humans in Space d.Upstream drivers of space weather 3.Extreme events 4.Long-term change 5.Summary

What is space weather? Space weather is the physical and phenomenological state of natural space environments. The associated discipline aims, through observation, monitoring, analysis and modelling, at understanding and predicting the state of the sun, the interplanetary and planetary environments, and the solar and non-solar driven perturbations that affect them; and also at forecasting and nowcasting the possible impacts on biological and technological systems. Text: courtesy COST Action 724 Image: courtesy L. Lanzerotti

Upper atmosphere Dominates (~90%) economic impact of Space Weather –Potentially large Euro market for SpW services Effects include drag, radio propagation, induction sources Comms/GNSS Scintillation – loss of phase lock SAR – along-track coherence of ionospheric path D region – absorption X-ray flares, protons E/F region – reflection/refraction – magnetic storms/aurora

Energetic particles in space Strategic issue for spacecraft design & operations –Potential Euro market for SpW services Diverse space-based effects –charging – by keV-MeV electrons (rad belt, aurora, plasmasheet, SEP) –radiation damage (e.g. solar cells, DNA) – by > MeV ions (rad belt, SAA, solar events, cosmic rays) –single event effects (state changes in microelectronics) – by >> MeV ions (rad belt, solar events, cosmic rays) Image: courtesy ESA Cluster array power

Very energetic particles (> GeV) penetrate the atmosphere –Cosmic rays, solar energetic particles –Influx controlled by geomagnetic field (highest at poles) –Collisions generate secondary neutrons (peak flux ~ 20 km, significant at 10 km, some flux at surface) Cause significant single event effects in avionics SEE now growing issue for ground-based electronics –dominant factor limiting reliability of digital electronics –major issue for safety-critical systems, e.g. in cars –also issue for range of high-voltage power systems Cosmic rays also influence atmosphere –Clear link with cloud cover in maritime regions (Harrison, 2006) –Can ~100 keV electrons from cosmic rays seed lightning strokes? Energetic particles in the atmosphere … semiconductor memory failures induced by cosmic radiation are no longer an “aerospace problem”. Such failure mechanisms must be accounted for in automotive electronics systems design. June 2006

Humans in space Radiation is direct hazard to astronauts –DNA damage, increased cancer risk, Space station protected by Earth’s magnetic field Moon and Mars are NOT protected The luck of Apollo Danger on Mars radiation hits on rover camera

Upstream drivers Space Weather is a natural hazard – a consequence of living near a star –Analogous to living next to volcanoes, rivers, etc Courtesy NASA Need to understand science that controls this environment –Behaviour of that star –How energy and momentum propagate to our planet Propagation includes –Solar wind + embedded magnetic field –Plasma transport across magnetopause (confinement boundary) –Magnetosphere-ionosphere coupling – magnetically guided Common physics with magnetically confined plasmas for fusion

Extreme Events But they are rare – so main issue is detection and then patience until normal conditions return. Which critical systems need to cope? How to advise users on the day? Extreme events are important as they produce major disruption often beyond scope of routine mitigation.

Long-term change in SpW Solar change –Are we at grand (300-year) maximum in solar activity (& its effects at Earth)? –Will 21 st century see collapse in activity (similar to 17 th century)? –What are consequences: enhanced cosmic ray fluxes, bigger solar particle events? Green-house gases –Will cool upper atmosphere –Some evidence in long-term ionospheric data-sets –Also evidence from EISCAT continuous run for IHY Geomagnetic field –Westward motion of SAA –Decline in magnetospheric protection Rising trend in geomagnetic activity

SUMMARY Space Weather has increasing impact on people and technology –Not limited to space, has very profound effects in upper atmosphere and applications therein –Growing awareness of sea-level effects and their impact on applications (e.g. electronics, power grids, etc). –Has role in “Space Situational Awareness” Highlights need to understand space environment