Self-Healing in Space

Ethan Wong

March 28th, 2025

Whether recreating another space station to replace the ISS, or developing spacecraft for longer and farther missions–a 9 month journey to Mars–it would be tedious and tiresome for astronauts to have to tackle minor damages to their equipment. Even minor issues could be worrisome for distant missions, even if they don’t compare to the malfunctions of Apollo 13. For years now, NASA has developed and improved upon “self-healing” materials which can be used to effectively remedy minor damages from orbital debris (through high-velocity collisions), long-term radiation exposure, or other occurrences without the need for astronaut troubleshooting; thus, from solar panels and cells on satellites and spacecraft (and even telescopes), to the exterior materials of spacecraft, these self-healing materials have plentiful potential usage, and such innovations will continue to grow humans plan increasingly long missions to explore our Solar System.

One of the simplest designs for a self-healing material, created by NASA, involves a double-sided plastic polymer solid border which encapsulates a liquid monomer substance in-between. The best way to picture it is by imagining a candy bar–solid chocolate walls which surround a caramel center. When a puncture is created, such as from debris impact, both the solid exterior walls and the liquid help heal the wall without human or robotic operations. First, the walls are initially misshapen, and their flexibility allows the damages to be partially fixed if the impact generates enough heat to melt the walls; additionally, the liquid monomer inside becomes highly reactive if exposed to oxygen, allowing it to fix any punctures or small “impact wounds” that are not resolved by the walls.

NASA has also developed “self-healing” for electric wire insulation. Electric wire insulation is an important safety check for spacecraft, as lack of proper insulation can cause problems such as short circuiting, and malfunctions (and even spark fires). NASA’s “self-healing” technology utilizes solvent-soluble polyimides, which allow polyimides to be dissolved/melted in solutes compared to traditional polyimides that are tough and resistant. In general, polyimides are essentially just a durable polymer often used with electronic components like wires. While these NASA-altered polyimides can re-bond themselves for minor damages, small microcapsules are also a solution. When solvent-soluble polyimides are not an option, microcapsules will release healant when a wire is damaged, which will help the polyimides dissolve and reform the damaged portion of the insulation. The polyimide would then become a solid again, preventing exposed wires. While no human participation is required for either method of “self-healing,” the altered polyimides work many times, while a microcapsule cannot be filled up and re-burst on its own. 

What about more recent developments? In 2024, metal-halide perovskite was another proposed material to benefit space missions in the future by improving solar panel and cell resistance to long-term radiation exposure. Metal-halide perovskite is lightweight, and would act as a thin film that would still be capable of converting sunlight into energy. The perovskite is soft, which allows the deformation of atoms in its lattice structure to be easily tolerable; on the other hand, current space solar panels and cells used on equipment like the James Webb Space Telescope are made of a stiffer silicon material, which have stronger lattice structures.

Many materials capable of “self-healing” (some of which discussed above) require the ability to easily adjust their internal structures on a molecular level. For instance, a common material used for spacecraft by NASA is Shape Memory Alloys (SMAs), which remember their initial state and are able to return to such shapes after being exposed to heat. Such technology works by having two lattice structures–martensite and austenite configurations–which can be alternated to avoid permanent deformation (martensite structure can have atom rearrangement when austenite structures at high temperatures are cooled rapidly), often caused by an irreversible change in a lattice structure’s bonding interaction.