Self-Healing Technology for Gas Retention Structures and Space Suit Systems

The health of inflatable structures, including space suits and habitats, is dependent upon the integrity of the gas retention structural layer. Inflatable structures typically utilize a coated fabric gas retention layer, or bladder. Threats such as Micrometeoroid and Orbital Debris (MMOD) penetration and inadvertent impact with sharp objects can cause a breach of the gas retention layer. Leakage as a result of bladder breach will impact operations due to loss of consumables and time spent locating and repairing the defect. Crew safety can be at risk where high rate leakage could cause loss of mission or loss of life. ILC has recently researched self-healing technologies that prevent leakage by closing penetrations of the gas retention structure and that are viable and scalable for various future missions and applications ranging from the Constellation Space Suit System (CSSS) to deployable lunar habitats. Several candidates of passive self-healing systems were studied. System impacts such as the size of the hole that can be healed, material mass and thickness, and system inflation pressure were considered. Candidates were evaluated based on derived requirements for a flexible inflatable system. In 2001 a Shuttle Space Suit Assembly (SSA) lower arm component prototype with a viscoelastic gel self-healing bladder was fabricated and puncture tested in vacuum. The performance of this viscoelastic gel solution was used for comparison with new concepts that have recently been developed and tested.

This paper will provide an overview of self-healing concepts identified in the recent InFlex Habitat Study. Details of testing and performance of selected self-healing concepts are included. System attributes including material properties, functionality with all puncture threats, scalability, manufacturability, operational life, and cost are discussed. Future work including investigation of a microencapsulation concept is also described.