Life support and radiation shielding are two critical technologies for manned exploration missions. For long duration missions, life support resources, such as water and food, must be provided to keep the crew alive and shelter must be provided to protect the crew from radiation. The large amounts of food and water required for long duration missions have been the major reason for developing closed loop life support systems. However, preliminary findings indicate that food and water can be effective as radiation shielding and may result in significant mass savings over dedicated shielding. This dual use of life support resources reduces overall system mass as well as the mass penalty associated with open loop life support.