Thermal Conductivity Testing of Radiation Shielding Materials for Use as Thermal Insulation

The Vision for Space Exploration (VSE) requires vehicles and crew systems designs that include space radiation shielding and protection. Astronauts venturing beyond low Earth orbit (LEO) outside the protection of the Earth's geomagnetic field will be exposed to a much harsher radiation environment due to the potential for solar particle events (SPE). Additionally, long duration missions will subject the crew to higher doses of galactic cosmic rays (GCR). The incorporation of radiation shielding technology into sub-system elements will be crucial to the success of future vehicle designs. One area where radiation shielding may be incorporated is the thermal insulation. As with current crew systems, thermal protection will be a key element in the design. Incorporating radiation shielding into thermal protection systems may be possible by using polymer spheres in place of traditional multi-layer insulation (MLI). By using spheres manufactured from hydrogen rich polymers, which are known to provide a level of shielding against SPE and GCR, the complexity of a system can b e reduced. Using a packed bed of spheres as insulation also allows for the possibility to operate in a w ea k vacuum such as that found on Mars. Under a Phase 1 SBIR contract with the Marshall Space Flight Center (MSFC), a thin heater test apparatus was developed and various polymer sphere samples were tested in both high vacuum and low pressure gas for determination of effective thermal conductivity. The results show that there is potential in the use of polymer spheres as an insulation system.