Human space exploration enterprise requires cost reductions in space operations. Unfortunately, human spaceflight has higher operational costs, due to space-related environmental hazards to humans. Any individual in the space environment has limited space radiation exposure time allowance because of the health risks involved. Prevention of radiation sickness, functional impairment of the central nervous system, and cancer increase the operational costs. Ultimately, radiation doses must be maintained below than 3 per cent lifetime excess fatal cancer risks. The norm for the whole body exposure in LEO is 25 cSv in any 30-day period, 50 cSv within any year, and 100 - 400 cSv within a career.
Low earth orbit environment protons are the primary source of radiation. However, for deep space operations, proton exposure are not relevant. The exposure hazard comes mainly from galactic cosmic rays. So, LEO exposure limitations are not applicable to the deep space operations. Uncertainty in shield requirements drives the operational and launch costs higher. According to the different institutions, for protons, 2.5 gr/cm2 - 17.5 gr/cm2 and for galactic cosmic rays, 50 gr/cm2 of aluminium is required to meet the annual exposure limit. These requirements project negative impact on mission developmental costs of human spaceflight.
At Belpico we are developing NATAN, a hydrogen-containing advanced polymeric material with boron reinforcement. Experimental investigations show great structural stability, and high shielding capabilities for human protection can be accomplished with NATAN. The preliminary results demonstrate that NATAN has superior energy absorption from the low-energy neutron exposure. Hence, NATAN provides sufficient shielding technology for human protection from space radiation. Also, NATAN has acceptable thermomechanical properties advanced mechanical properties, such as high compressive strength and modulus. Once operational NATAN will reduce the operational and launch costs of human space exploration.