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Dave Brain UC Berkeley Space Sciences Lab (Hi folks! Sorry I couldn’t make it!)

Space Weather Events at Mars: Spacecraft Observations and Consequences for the Atmosphere and Surface. Dave Brain UC Berkeley Space Sciences Lab (Hi folks! Sorry I couldn’t make it!). 10’s MeV ions. 10-20 keV electrons. . Count Rate. Count Rate. . ER. Energy. Energy.

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Dave Brain UC Berkeley Space Sciences Lab (Hi folks! Sorry I couldn’t make it!)

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  1. Space Weather Events at Mars:Spacecraft Observations and Consequences for the Atmosphere and Surface Dave Brain UC Berkeley Space Sciences Lab (Hi folks! Sorry I couldn’t make it!)

  2. 10’s MeV ions 10-20 keV electrons  Count Rate Count Rate  ER Energy Energy MGS ER “Background” ‘High’ energy channels of electron instrument record 10-20 keV electrons and energetic ions Comparing count rates in these 3 channels allows determination of which particle populations contribute to observations

  3. A Space Weather Event at Mars shock arrival ‘real’ electrons present ‘real’ electrons present quiet time data dropouts MGS observations best for obtaining timing information at 1.5 AU, and qualitative info about fluxes of 10’s MeV ions and 10-20 keV electrons

  4. SEP Events at 1.5 AU1999-2005 More than 50 events (over 5 years) of enhanced background Count rate exceeds 50 counts/second ~4% of the time

  5. March 2003 SEP Event The radiation detector on Mars Odyssey saw modulations in the count rate at the S/C orbital period during a SEP event The MGS electron instrument also saw modulations at the S/C orbital period. But the event started much later at MGS! ER background count rate MARIE and ER likely sensitive to different particle energy ranges

  6. March 2003 SEP Event ‘real’ electrons last page • The event(s) observed by MARIE lasted beyond March 19 • Largest increase in solar wind pressure occurred late on March 21, • after decline in particles and during subsequent event • IMF changes direction on the 19th from dawnward to duskward • 10-20 keV electrons observed through the 25th

  7. Dropouts Dropouts in ‘background’ count rate observed during SEP events 10-20 keV electrons removed Are 10’s MeV ions removed? Why do the dropouts occur?

  8. Dropouts Some dropouts associated with shadow entry/exit S/C shielding effect? Electric fields? Ionospheric clouds?

  9. Dropouts ? Some dropouts associated with Martian crustal sources Crustal fields exclude 10-20 keV electrons?

  10. More Dropouts Dropouts during more intense July 2002 event are associated primarily with leaving shadow in southern hemisphere, and crustal magnetic fields

  11. And Still More Dropouts No dropouts before shock arrival  dropouts in 10-20 keV electrons only

  12. Solving the Mystery • Observed by MGS Electron instrument: • Oscillation in quiet time background • Many SEP events • Elevated ‘background’ count rates during SEP events (10’s MeV ions) • 10-20 keV electrons after shock arrival • Dropouts in background count rate during SEP events • correspond to shadow entry/exit • correspond to crustal magnetic fields • Plenty more to do… • What is going on? • Detailed physical interpretation tantalyzingly difficult (argh!) • Dedicated instruments likely required • SEP detector (10’s MeV to 1 GeV) • Clean electron measurements • Solar wind monitor (IMF, dynamic pressure)

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