Accelerator-Based Tests of Radiation Shielding Properties of Materials Used in Human Space Infrastructures

Abstract

Shielding is the only practical countermeasure for the exposure to cosmic radiation during space travel. It is well known that light, hydrogenated materials, such as water and polyethylene, provide the best shielding against space radiation. Kevlar and Nextel are two materials of great interest for spacecraft shielding because of their known ability to protect human space infrastructures from meteoroids and debris. We measured the response to simulated heavy-ion cosmic radiation of these shielding materials and compared it to polyethylene, Lucite (PMMA), and aluminum. As proxy to galactic nuclei we used 1 GeV n iron or titanium ions. Both physics and biology tests were performed. The results show that Kevlar, which is rich in carbon atoms (about 50% in number), is an excellent space radiation shielding material. Physics tests show that its effectiveness is close (80-90%) to that of polyethylene, and biology data suggest that it can reduce the chromosomal damage more efficiently than PMMA. Nextel is less efficient as a radiation shield, and the expected reduction on dose is roughly half that provided by the same mass of polyethylene. Both Kevlar and Nextel are more effective than aluminum in the attenuation of heavy-ion dose.

Space radiation protection: Destination Mars

“…Accelerator-based Polyethylene is clearly better than Al, and Kevlar is close to polyethylene. Measurements at the Brookhaven National Laboratory (Upton, NY), figure modified from Lobascio et al (2008). measurements are in those cases an essential tool to characterize the shield. The simplest test is the measure of the Bragg curve using heavy ions at high energy (Fig.…”

“…The same method has been used to estimate the shielding effectiveness of Kevlar and Nextel (Fig. 4) (Lobascio et al, 2008), commonly used against micrometeorites in space structures, and of the composite materials in the walls of the Columbus module on the ISS (Silvestri et al, 2011). ESA is currently sponsoring a set of measurements at GSI in Germany to test in situ planetary materials (Mars and moon regolith) and new materials with very high hydrogen content and excellent structural properties (Fig.…”

Validation of Geant4 physics models for 56Fe ion beam in various media

“…The target of a three dimensional box was employed as a phantom material having uniform density. These materials are used in simulation work in terms of their fractional mass as (1) water [16] (q = 0.997 g/cm 3 ): 66.67% hydrogen, 33.33% oxygen; (2) polyethylene (q = 0.97 g/cm 3 ): 33.33% carbon, 66.67% hydrogen; (3) kevlar (q = 1.44 g/cm 3 ): 71% carbon, 13% oxygen, 12% nitrogen, 4% hydrogen; (4) nextel (q = 2.7 g/cm 3 ): 52% oxygen, 33% aluminum, 11% silicon, 4% boron [6]. The target area (200 Â 200 mm 2 ) facing the beam was kept perpendicular along the direction of the incident beam.…”

“…Even though heavy ions of charge Z = 3-92 are far less abundant (1%) than protons (87%) in galactic cosmic rays (GCR), they are significant importance because of their high relative biological effectiveness (RBE) [1][2][3][4]. GCR, trapped particles, fragmentation products, recoil nuclei and neutrons cause the major health risk to astronauts, electronics and scientific equipment in a spacecraft [5][6][7][8][9][10]. The space radiation spectrum is a complex mixture of charged and uncharged particles with energies from few MeV/n to TeV/n [1].…”

“…Light hydrogenated materials, such as water and polyethylene are mostly used to study physical and biological effects of space radiation [12][13][14][15] and liquid hydrogen is the second best shielding material against GCR [1]. A better protection from meteoroids and debris in low earth orbits could be provided by composite materials such as nextel and kevlar [6]. The depth dose profiles for 12 C ion beam in water and polyethylene media were explained by Lechner et al [16] on the basis of the G4QMDReaction model.…”