Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module Crew Quarters

Polyethylene as a radiation shielding standard in simulated cosmic-ray environments

“…Since there is no generally agreed-upon method of quantifying shielding effectiveness, a simple analysis using the first and second moments of the LET distributions, implemented in previous analyses [6,7], is used again here. These values, the track-and dose-averaged LET, are closely related to energy deposition and, therefore, to absorbed dose.…”

“…For most of the particles and energies found in the Galactic Cosmic Ray (GCR) spectrum, the effectiveness of a material as a radiation shield generally increases with decreasing atomic number, with hydrogen being the best [3,4], as described in detail in the accompanying paper [5], in which many materials were tested in a beam of 1 GeV/amu 56 Fe ions at the Brookhaven National Laboratory's Alternating Gradient Synchrotron (AGS). Since hydrogen is highly effective, one would expect polyethylene, CH 2 , with two hydrogen atoms and one carbon atom per molecule, to also be an effective shielding material, and in fact blocks of it have been added to the crew sleeping quarters on the International Space Station to provide radiation protection [6,7]. Furthermore, polyethylene is readily available, non-toxic, and chemically stable under typical conditions, making it a convenient reference material for shielding tests at heavy-ion accelerators.…”

Measuring space radiation shielding effectiveness

“…Therefore, a new definition of shielding effectiveness, defined in terms of a reference material and applicable to accelerator beam measurements, is proposed. The relative shielding effectiveness f is defined as the ratio of the mass stopping powers for the material-undertest (MUT) and the reference material (RM), as shown in Equation 1. Note that implicit dependence on the particle type and energy is suppressed in this formulation.…”

“…In the past, passive shielding studies have focused on using additional mass for the primary purpose of space radiation protection [1,2]. However, adding mass for no purpose other than radiation shielding is unpalatable due to the limited launch capability of rockets and the mass required to sustain astronauts for extended periods of time for missions with destinations outside of low-Earth orbit.…”

Biopharmaceutical Challenges of Therapeutics in Space: Formulation and Packaging Considerations

“…On large scales, inert gases have been considered for the protection of spacecraft, but on the small scale, their use in custom manufacturing directly by the pharmaceutical industry may potentially enhance the shelf life of drugs, if not through shielding then by reducing oxidation. Concepts of radiation attenuation by applying portable shielding using lightweight materials, such as high-density varieties of polyethylene (water-, tungsten-and boron-impregnated), may be applicable in the design of medical kits and drug dispensers for long-duration missions [22]. New materials with multiple interfacial layers providing both def lection and attenuation characteristics, such as hydrated organic capillary-porous matrices may also be of interest as shielding materials.…”