Development and Testing of a Lunar Standardized Payload Rack

Space habitats are highly complex systems, with the added constraint that the lives of the astronauts are dependent on the continued functionality of the equipment. Habitats such as the International Space Station are designed around a modular equipment rack, the International Standardized Payload Rack (ISPR). Racks can be interchanged within a pressurized habitat module, and can in turn mount a number of subsystems which can be removed for maintenance or replacement. While it would make sense to continue this approach for lunar surface habitats, the presence of lunar gravity will make the current ISPR design infeasible due to the need to move it under lunar weight. This paper summarizes recent research at the University of Maryland on the design and testing of a “Lunar Standardized Payload Rack” (LSPR) system for lunar and Mars habitats, while maintaining suitability for use in microgravity applications. The requirements for this system mirror that of the ISPR, with additional constraints that the units must be human-transportable in an appropriate gravitational environment, while also being compatible with current and planned future pressurized mating adapters. Initial testing focused on the limitations of human capability for mass transport, simulating lunar and Mars gravity levels via ballasted underwater testing. Once the weight limits for human transport were established, the maximum outer envelope of the LPSR was identified, and detailed designs performed to accommodate requirements for electrical, data, fluid, and mechanical interfaces. A higher fidelity LSPR rack was fabricated and populated with components representative of a life support system, which was then used to evaluate the design’s functionality in the five critical steps in its lifetime: transport, installation, operation, maintenance, and removal. These tests were again performed in underwater simulation of lunar and Mars gravitational fields.