The ALTEA and ALTEA-Shield experiments onboard the International Space Station L. Di Fino, M. Larosa, L. Narici, V. Zaconte University of Rome Tor Vergata

Scientific goals ALTEA (Anomalous Long Term Effects on Astronauts) – PI: Prof. L. Narici Exposure of crew to space radiation poses one of the most significant hazards to space permanence. A quest for understanding the risks for the Central Nervous System (CNS) during long permanence in space due to cosmic rays exposure. Rationale: anomalous Light Flash perceptions suggest that abnormal (though possibly transient) CNS functional states may result Theoretically predicted by Tobias: Tobias C.A. 1952 J. Aviat. Med. 23 345 First observed in 1969 by Aldrin during Apollo-11 mission Scientific strategy: detailed measurement of radiation environment (DOSI) measurement of transient/long-term functional effects of space environment and cosmic radiation on the CNS (CNSM) survey of the radiation environment in space habitats (Survey) test of shielding materials as countermeasures for CNS functional risks (Shield)

ALTEA-Space facility Particle Detector (Silicon Detector System) 6 Silicon Detector Units (SDU) 6 silicon planes – 8x16 cm2, 380 mm thick Geometrical factor SDU 230 cm2sr SDS 1180 cm2sr Detectable LET range: 3 - 800 KeV/mm DOSI – CNSM configurations EEG, VSU, Pushbutton DAU Survey configuration

ALTEA facility onboard ISS Onboard ISS since July 2006 2006-2007 ASI experiment 2009-2010 NASA-SRAG experiment 2010-2011 ESA experiment > 800 days of acquisition time > 1 billion triggers

ALTEA facility onboard ISS 2006 2007 2008 2009 2010 2011 2012

ALTEA configurations DOSI (Dosimetry) ALTEA-Shield Survey Realtime measurement of radiation flux Total acquisition time 2006-2007: 224 days 2009-2010: 320 days ALTEA-Shield Survey Same as DOSI Different 3D holder Measurements in 4 different positions Total acquisition time 2006-2007: 281 days CNSM (Central Nervous System Monitoring) During a 90-minute session the astronaut wears EEG cap, slides under the SDS and signals LF perceptions 2006-2007: 7 sessions

Realtime data ALTEA data are downloaded and analyzed in realtime at the ALTEA User Home Base (UHB) at University of Rome Tor Vergata. A subset of ALTEA realtime data is publicly available through the NASA iNTEGRATED SPACE WEATHER ANALYSIS SYSTEM (iSWA) web application. http://iswa.ccmc.gsfc.nasa.gov

Particle Rate 6 SDUs, triggered particles pole/equator and orbit precession modulations increment during passages on the SAA

Particle flux and ion abundances Filter fast particles (ΔE ~ Z2) Fit with a sum of Landau functions

December 2006 Solar Particle Event

Integrated Particle Fluxes and LET rates Integrating Particle flux and LET rate: X e Y direction: theta e phi ± π/8 intorno all’asse Z direction: θ < 3/16 * π

Particle flux anisotropy LET rate

Conclusions The ALTEA-Space facility onboard ISS is used since 2006 in different experiments supported by all major space agencies. It delivered a detailed measurement of the radiation environment inside the UsLab, several measurements on astronauts and a survey of the radiation environment in different positions. A strong anisotropy (up to a factor 3 in LET) was found when considering high LET particles (LET > 50) coming from different directions. The second step of ALTEA-Shield (Shield) experiment is planned in 2012 to test the effectiveness of different shielding materials and thicknesses A collaboration with Jaxa is under consideration for further measurements on astronauts At last… we are looking for students!

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