The dose incurred in an environment generated by extraterrestrial space radiations within an anisotropic shield distribution depends on the orientation of the astronaut's body relative to the shield geometry. The fluctuations in exposure of specific organ sites due to astronaut re-orientation are found to be a factor of 2 or more in a typical space habitation module and typical space radiations. An approximation function is found that overestimates astronaut exposure in most cases studied and is recommended as a shield design guide for future deep space missions.