Space Weather Activities at NSSTC

Space Weather Activities at NSSTC Oklahoma Space Grant Tour Dr. David H. Hathaway NASA/MSFC/NSSTC 2007 March 23 Space Weather Space weather refers to conditions on the Sun and in the space environment that can influence the performance and reliability of space-borne and groundbased technological systems, and can endanger human life or health. Sources of Space Weather 1. Photons (X-rays, EUV) 2. Energetic Particles (Protons) 3. Magnetized Plasma Example: The Bastille Day Event The flare, seen in EUV, emits energetic photons and accelerates particles. The coronal mass ejection, also accelerates particles and ejects magnetized plasma from the Sun. The energetic particles shower the imaging instruments on SOHO minutes later. Space Weather Effects Effects of Solar Activity: On Human Space Flight Shuttle missions and EVAs require particular attention. The Space Radiation Analysis Group (SRAG) reports to Mission Control when: K-index > 6, X-Ray Flux > M5, Protons at >100 MeV > 50. ISS: 50 pfu at > 100 MeV - shutdown the robotic arm 100 pfu at > 100 MeV - alert Mission Control. The Flight Team will start to evaluate a plan to shutdown equipment to prevent damage. 200 pfu at > 100 MeV - plan is implemented Effects of Solar Activity: On Satellites Radiation (protons, electrons, alpha particles) from solar flares and coronal mass ejections can damage electronics on satellites. Heating of the Earth’s upper atmosphere increases satellite drag. •1991 GOES •1995 Deutsche Telekom •1996 Telesat Canada •1997 Telstar 401 •2000/07/14 ASCA •2003 Mars Odyssey •4500 spacecraft anomalies over last 25 years Effects of Solar Activity: On Power Grids Solar disturbances shake the Earth’s magnetic field. This sets up huge electrical currents in power lines and pipe lines. The solar storm of March 13th 1989 fried a $10M transformer in NJ. The same storm interrupted power to the province of Quebec for 6 days. Effects of Solar Activity: On Airline Operations HF Communication only • Polar flights departing from North America use VHF (30-300 MHz) comm or Satcom with Canadian ATCs and Arctic Radio. • Flights rely on HF (3 – 30 MHz) communication inside the 82 degree circle. • Growth: Airlines operating China-US routes goes from 4 to 6 and then number of weekly flights goes from 54 to 249 over the next 6-years. Effects of Solar Activity: On Climate? Yearly Sunspot Numbers and Reconstructed Northern Hemisphere Temperature (Mann, Bradley & Hughes Nature 392, 779787, 1998) smoothed with an 11-year FWHM tapered Gaussian and trimmed to valid smoothed data. The correlation coefficient from the overlapping period is 0.78 but the physical mechanism linking the two is unknown. The Solar Sources of Space Weather The “11-year” Sunspot Cycle The sunspot cycle was discovered by Heinrich Schwabe in 1844 from 18-years of personal observations. The cycle periods are normally distributed about 131 months with a variance of 14 months. Sunspot Number and Solar Activity Sunspot number is well correlated with other indicators of solar activity. The long record of sunspot numbers helps to better characterize the solar cycle. Predicting the sunspot number also provides an estimate of these other source of solar activity. Sunspot Area 10.7cm Radio Flux GOES X-Ray Flares Total Irradiance Geomagnetic aa index Climax Cosmic-Ray Flux Magnetic Fields are Behind all Solar Activity The Sun’s Magnetic Cycle •The high conductivity of the fluid within the Sun makes the magnetic field and the fluid flow together (frozen in field lines). •The high pressures found inside the Sun insures that the fluid flow controls the magnetic field (except in the centers of sunspots). Dynamos with Meridional Flow Recent Dynamo models incorporate a deep meridional flow to transport magnetic flux toward the equator at the base of the convection zone. These models explain the equatorward drift of activity, the poleward drift of weak magnetic elements on the surface, the length of the cycle from the speed of the flow, and give a relationship between polar fields at minimum and the amplitude of future cycles. Dikpati and Charbonneau, ApJ 518, 508-520, 1999 The Dynamo Prediction Dikpati, de Toma & Gilman (2006) have fed sunspot areas and positions into their numerical model for the Sun’s dynamo and reproduced the amplitudes of the last eight cycles with unprecedented accuracy (RMS error < 10). Cycle 24 Prediction ~ 165 ± 15 Magnetic Field and Solar Flares Flares are likely to occur when the magnetic field along the neutral line between opposite polarity regions is sheared or twisted from the direction given by the potential field. Vector Magnetograms are needed to determine the presence of this magnetic shear. Correlations with CMEs Red + => CME Blue + => no CME Magnetic Models for CMEs Current Missions Ulysses (ESA/NASA – 1990) SOHO (ESA/NASA – 1995) TRACE (NASA – 1998) RHESSI (NASA –2002) STEREO (NASA -2006/08) Hinode (Japan/US/UK –2006/09) Future Missions Solar Dynamics Observatory (NASA -2008/08) Solar Sentinels (NASA/ESA? -2012?) The Earth’s Response to Space Weather Coronal Mass Ejections Interact with the Earth’s Magnetosphere Magnetic Models for Geomagnetic Activity Ground-Level Response A Space Weather-observing “constellation” of satellites Conclusions • Space Weather must be understood and reliably predicted for safe and successful space exploration • Additional scientific research is needed to do this http://solarscience.msfc.nasa.gov/