The ALTEA and ALTEA-Shield The ALTEA and ALTEA-Shield experiments onboard the experiments onboard the

International Space StationInternational Space Station

L. Di Fino, M. Larosa, L. Narici, V. ZaconteL. Di Fino, M. Larosa, L. Narici, V. ZaconteUniversity of Rome Tor VergataUniversity 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. 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)

Scientific goals

• Particle Detector (Silicon Detector System)6 Silicon Detector Units (SDU)

6 silicon planes – 8x16 cm2, 380 m thickGeometrical factor

SDU 230 cm2srSDS 1180 cm2sr

Detectable LET range: 3 - 800 KeV/m

ALTEA-Space facility

• EEG, VSU, Pushbutton• DAU

DOSI – CNSM configurations

Survey configuration

ALTEA facility onboard ISS

Onboard ISS since July 20062006-2007 ASI experiment2009-2010 NASA-SRAG experiment2010-2011 ESA experiment

> 800 days of acquisition time> 1 billion triggers

ALTEA facility onboard ISS

2006 2007 2008 2009 2010 2011 2012

DOSI (Dosimetry)Realtime measurement of radiation flux

Total acquisition time2006-2007: 224 days2009-2010: 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

2006-2007: 7 sessions

ALTEA configurations

ALTEA-Shield SurveySame as DOSIDifferent 3D holderMeasurements in 4 different positions

Total acquisition time2006-2007: 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.http://iswa.ccmc.gsfc.nasa.gov

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

Particle Rate

• Filter fast particles (ΔE ~ Z2)• 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 anisotropy

ConclusionsThe 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

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