1. RADIOPROTEZIONE DEGLI ASTRONAUTI DA RADIAZIONE COSMICA
Gianfranco Grossi
Dipartimento di Scienze Fisiche
Università di Napoli Federico II
INFN - Sezione di Napoli

2. The places we will go if radiation doesn’t hold us back
Earth and LEO
The Earth’s Neighborhood
Accessible Planetary Surfaces
Outer Planets
Earth-Moon L1
The
Moon
Sun-Earth L2
Mars
Asteroids or Other Targets...
Up to 180 days L1
Risk of cancer lethality
(4  8) x 10-2 per Sv L2
Up to 100 days
500 to 1000 days
> 2000 days
Dose - rate: 1 mSv/d
2 mSv/d
3 mSv/d

3. The problem
Long-term interplanetary missions are planned in the XXI century
Crews will be exposed to significant doses delivered by high-energy charged particles, in extreme conditions (stress, microgravity,..)
Uncertainties on radiation risk estimates in deep space are between 400% and 1500%
Uncertainty must be reduced for safe
human colonization of the solar system

4. “Best” shielding materials
Projectile interactions per unit target mass:
Ionization ~ Z/A
Fragmentation ~ A-1/3

5. HZE shielding
Shielding of heavy ions is complicated by nuclear fragmentation
Projectile fragmentation produces swift light ions and neutrons
Target fragmentation produces slow, densely ionizing ions
Fragments have different Q than primary ions

6. GCR shielding - calculation by HZETRN
Aluminum ~ 30%
Polyethylene ~ 50%
Liquid hydrogen ~ 90%
Max GCR dose reduction

7. The SHIELD experiment
SHIELD started in 1999: 4 Italian research Institutes, NASA JSC, BNL, and NIRS (Japan)
Goal: study of biological effects of heavy ions with shielding
Results of experimental studies can be used to benchmark the codes
Different biological endpoints (CA, SV, DNA DSB) shield materials (LDPE, PMMA, C, Al, Pb) and thickness ( g/cm2), ion (H, C, Fe, Si, Ti) charge and energy ( GeV/n)
Results presented here are relative to the induction of chromosomal aberrations in human lymphocytes exposed to 56Fe projectiles with different shields

8. Chromosomal aberrations measured by FISH in PCC from human lymphocytes
Translocations involving chromosome 4 (left) and  2 (right). In light green chromosome 1, in red chromosome and in dark green chromosome 4

9. Nuclear fragmentation of AGS-BNL 56Fe beams
5 GeV/n 56Fe
5 GeV/n 56Fe + 25 cm PMMA
CR39 nuclear plastic detector

10. CA / 1 GeV/n 56Fe-particle vs. shield thickness
Effectiveness per Fe-particle incident on the shield is dependent on beam fragmentation, and is determined by combination of dose/particle and RBE-LET relationship

11. In-flight shielding test
Best candidate shielding materials from accelerator-based research should eventually be tested onboard against the whole spectrum of trapped and galactic radiation
ESA has recently approved two experiments to study shielding in orbit using the detectors ALTEINO and MATROSHKA on International Space Station
Two experiments (ESCHILO and RADIS) will flight in to test the shielding effectiveness of new composite materials and, for comparison, polyethylene.

12. Shielding on ISS Sleep station outfitted with polyethylene and water
Thin, flat panels are polyethylene shields
Stowage water packaging above the sleep station

13. ESCHILO (Esperimento di Schermatura in Low Orbit)
Measurements of shielding on ISS (INFN, University Tor Vergata, Alenia Spazio, University Federico II)
PI: Marco Casolino
Detector: ALTEINO on ISS
Shield: two multimaterial tiles divided into 4 sections

14. RADIS (Radiation Distribution)
Large (23 Institutes, led by DLR, Germany) scientific collaboration to use MATROSHKA inside the ISS (from May 2005)
University Federico II is supposed to provide shielding materials to cover MATROSHKA and measure the changes in dose, flux, radiation quality, etc. at various depths in the phantom.

15. Marco Durante
Giancarlo Gialanella
Gianfranco Grossi
Lorenzo Manti
Mariagabriella Pugliese
Paola Scampoli