Over the past three years, NASA has been studying the operational effectiveness and astronaut protection efficacy of numerous radiation protection shelters for use in space exploration activities outside of Earth's magnetosphere. The work was part of NASA's Advanced Exploration Systems (AES) RadWorks Storm Shelter project. Fabricated items were integrated into mockup deep space habitat vehicle sections for operational evaluations. Two full-scale human-in-loop simulations were designed, fabricated, and implemented. The goal was to provide design and performance assessment information for consideration by mission designers who must quantify the radiation protection characteristics of their exploration trade space.
One element of the AES RadWorks effort was to characterize radiation protection effectiveness of approaches intended primarily for dose reduction during a Solar Particle Event (SPE). This protection, intended to be in place only as long as necessary for the duration of an SPE, is termed a radiation Storm Shelter. Two basic operational concepts showed merit: one that involves building a temporary shelter (“Reconfigurable Logistics“), and another based upon using a crewmember's personal living quarters area as a shelter location (“Crew Quarters“).
The Reconfigurable Logistics approach is a shelter fabricated from various logistics items fastened to a supporting structure within the hallway of a typical International Space Station (ISS)-style crew habitation element. The logistics of various nature — food, water, processed trash, and waste — are depicted as uniform-sized packages used to tile the support structure. Thus items of useful protective mass are moved from an operating storage location for the purpose of building a localized SPE shelter, and little additional mass is required for protection over what is nominally available during station operations. This is a low parasitic mass approach.
The Crew Quarters configuration was selected to be studied as protected by both some reconfigurable logistics, but also by use of a waterwall integrated into the design of the Crew Quarters so that potable water on an exploration mission could be stored to provide a crewmember protection from external radiation. Ideally, such a water storage location, between the crew and the most intense radiation source, would be the normal operating approach, but water could be diverted to this location in the event of an SPE if it were nominally stored in a different location.
It was found to be advantageous to keep crew surrounded by logistics and element subsystems for as much time as possible. As a design example, crew quarters located down the center of a cylinder with logistics surrounding them in an annular manner could be a more advantageous arrangement than the typical ISS design with crew quarters on the perimeter of the habitat.