Assessment of radiation shielding properties of self-healing polymers and nanocomposites for a space habitat case study under GCR and LEO radiation

In recent decades, the opportunity to introduce self-healing materials within space structures has drawn the attention of scientists and companies. Autonomous repair following damage caused by impacts with micrometeoroids and orbital debris (MMOD) would lead to safer human activity in space and would increase spacecraft operational life and autonomy, thus reducing replacement costs and possibly relieving astronauts from maintenance activities. In particular, integrating self-healing materials into structures to protect humans from the space environment is a fundamental step in the realization of long-lasting space exploration missions. Nevertheless, the way these materials interact with the environmental factors in space still needs to be properly analyzed and understood; in particular, space radiation is a serious threat to human health and material integrity. The proposed work hence investigates the shielding ability of candidate self-healing materials with the specific purpose of human protection in crewed missions. The NASA HZETRN2015 (High Z and Energy TRaNsport, 2015 version) software is used to simulate galactic cosmic rays (GCR) and low Earth orbit (LEO) environment. A comparison between a standard habitat layup proposed by NASA and a set of configurations containing self-healing polymers is performed to verify that the substitution of conventional bladder materials with the proposed self-healing solutions does not decrease the overall habitat shielding performance. A self-healing nanocomposite option with single-walled carbon nanotubes (SWCNTs) is also analyzed to determine whether the insertion of nanofillers can increase the overall shielding performance. In the second phase, the comparison of puncture tests on blank and irradiated samples under conditions reproducing a space suit example is presented to assess the possible effects of radiation on the self-healing performance.