Spacesuit Radiation Shield Design Methods

Abstract

Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable. Transition to a new spacesuit design including soft upper-torso and reconfigured life support hardware gives an opportunity to optimize the next generation spacesuit for reduced potential health effects during an accidental exposure.

Effects of 100 MeV protons delivered at 0.5 or 1 cGy/min on the in vivo induction of early and delayed chromosomal damage

“…It was previously estimated that, during a journey to Mars, every cell in the body will be hit by a proton once every 3 days, and by a HZE ion approximately once a month [1]. Relating to SPEs, various organ dose rates ranging from 0 to 1 Gy/h [2] and doses ranging from 0 to 1 Gy [3] have been estimated. Hence, exposure to radiation during large SPEs can be life threatening.…”

Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions

“…In this case, the net slopes are plotted; i.e., slopes measured with radiation source minus slopes measured without the radiation source. The results demonstrate (1) a linear response from ambient GCR levels to the much higher dose rates possible from a large SPE, likely less than 100 mGy h −1 during EVA ( Wilson et al 2006 ) and much less inside a spaceship or a shielded planetary habitat; and (2) a reproducible response as observed for measurements made on different dates using two different gamma-ray sources. It is noted that a linear response was also observed for 241 AmBe neutrons tested over a similar range of slopes (from 0.0125 to 1.278 V s −1 ) at TAMU (data not shown).…”

Meeting Report--NASA Radiation Biomarker Workshop

“…Although protons from SPEs are of much lower energy than those from GCR (and therefore can be more readily shielded), they pose an acute health risk for astronauts who are exposed during extravehicular activity (EVA). For example, if an astronaut were participating in an EVA on the Moon during the August 1972 SPE and received the full radiation from that event, the doses are calculated to be 40 Sv to the skin, 5 Sv to the yellow marrow, and 1.7 Sv to the red marrow (11). These doses would have greatly exceeded the current 30-day dose limits established for LEO of 1.5 Sv for skin and 0.25 Sv for marrow.…”

“…In contrast, solar protons typically penetrate less than about 10 cm in water, and the vast majority penetrate less than 1 cm in water, barely enough to penetrate a lunar extravehicular activity (EVA) spacesuit (11). In addition to their differences in penetration power, the high-energy particles from GCR produce more secondary radiation via spallation reactions in materials.…”