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

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 J. Aviat. Med 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) Scientific goals

Particle Detector (Silicon Detector System) 6 Silicon Detector Units (SDU) 6 silicon planes – 8x16 cm 2, 380  m thick Geometrical factor SDU 230 cm 2 sr SDS 1180 cm 2 sr Detectable LET range: KeV/  m ALTEA-Space facility EEG, VSU, Pushbutton DAU DOSI – CNSM configurations Survey configuration

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

ALTEA facility onboard ISS

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

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.

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

Filter fast particles (ΔE ~ Z 2 ) Fit with a sum of Landau functions Particle flux and ion abundances

December 2006 Solar Particle Event

Integrated Particle Fluxes and LET rates

Particle Flux LET rate Particle flux anisotropy

UsLab survey ALTEA-Shield integral fluxes (Preliminary) Different positions and directions shows similar fluxes except for Position1-Y For LET>50KeV/  m direction X shows a flux attenuation as expected any LETLET > 50 keV/um

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!

Thank you for your attention!

Particle flux anisotropy in raw angular flux distribution is masked by the SDUs’ angular acceptance. A Montecarlo simulation (PHITS) of an isotropic flux was used to obtain each SDU angular acceptance. METHOD: use ALTEA as single detector To use ALTEA as a single detector we sum all the SDUs to obtain the angular acceptance of the whole ALTEA detector - R(  ).

Particle Flux LET rate Results: Poles Spectra ZoneBL PolesAny> 2 Equator> 2.5*10 -5 T< 2 SAA< 2.5*10 -5 T< 2

Particle Flux LET rate Results: Equator Spectra ZoneBL PolesAny> 2 Equator> 2.5*10 -5 T< 2 SAA< 2.5*10 -5 T< 2

Particle Flux LET rate Results: SAA Spectra ZoneBL PolesAny> 2 Equator> 2.5*10 -5 T< 2 SAA< 2.5*10 -5 T< 2

ALTEA - CNSM 7 sessioni eseguite, 3 Astronauti (1 sess + 2 sess + 4 sess) AstronautLFDuration (min)Mean interval (min) TOTAL AllE≤100 MeV/nE>100 MeV/n All18216 Z< Z≥ Numero di LF segnalati nelle sessioni CNSM Rate di particelle passanti per l’occhio (part/min)

ALTEA - CNSM Particella candidata (Z~3) alla generazione di un LF