Not Just for Supporting Pipe - the Use of Spring Hangers for Simulating Reduced Gravity

Abstract Space exploration requires the testing of a wide variety of vehicles and systems in terrestrial environments. The NASA Break the Ice Lunar Challenge was a multi-year competition to design, build, and test systems for excavating ice in craters on the moon, retrieve it, and make the water available for use in future lunar facilities. The culmination of this effort was a test campaign hosted by Alabama A&M University where the competing teams would test their excavation capabilities on simulated lunar ice. An engineering challenge associated with the competition was simulating lunar gravity acting on the excavation equipment, which is one-sixth of Earth gravity. While NASA has specialized equipment for gravity offload in their test facilities, the competition needed a gravity offload solution that: was robust enough to be used in a relatively uncontrolled environment where there would be dust and grit; could be easily adapted to the excavators developed by the competing teams that were of different sizes, weights, and configurations; and was available for reasonably low cost within a constrained schedule. To meet these requirements we used off the shelf piping spring hangers as the core of a gravity offload unit to support the competition. Modifications were made and other parts were added to enable the force applied by the spring to be easily measured and to efficiently switch springs between competitors. This paper discusses the requirements and challenges in more detail. It discusses the solution developed, and the pros and cons experienced based on the testing at the competition. Additionally, potential improvements will be noted.