Development of a Pressure Suit Simulation System for Neutral Buoyancy Operations

The current practice of using flight-type pressure suits for neutral buoyancy simulation is prohibitively expensive and severely limits testing opportunities. While final flight crew training is best performed in these high fidelity suits, many of the required neutral buoyancy activities, including basic research, engineering design validation, and procedures development, could be performed in lower fidelity pressure suit simulators without significant impact on test results. This paper reviews the Space Systems Laboratory's development of a simulation suit, specifically designed for neutral buoyancy operations. The Maryland Advanced Research/Simulation (MARS) Suit is designed to replicate the critical parameters of pressure suit activity, while greatly reducing the operational requirements of a high-fidelity suit system. The design incorporates a hard upper torso with integral helmet and backpack, and multilayer fabric arms and lower body unit. Rather than simply replicating an existing pressure suit, the MARS Suit design team has incorporated advanced features, including a rear-entry hatch and an oversized visor assembly which can accommodate high-resolution displays and experimental crew interfaces. Several design features have been selected in order to minimize the fabrication and operational costs of the system. Rather than support significant internal pressure, the MARS Suit is maintained at local ambient pressure, and motion limitations and force requirements of any desired existing pressure suit are replicated by mechanical design of the arm and leg garments. The internal environment of the suit is dry, enabling the use of biomedical sensors and communications systems without the complication of water immersion. In contrast to the existing Hamilton-Standard Extravehicular Mobility Unit (EMU) pressure suit, which requires intensive preparation and sizing for individual runs, the MARS Suit is designed to be easily reconfigurable. Simple, low-cost soft goods units for the arms and legs are specifically tailored for each subject, and can be quickly mated to a system of sized torso/visor/backpack assemblies. The backpack incorporates built-in systems for neutral buoyancy testing, including doubly redundant breathing air sources, suit instrumentation systems, and surface communications electronics. The backpack has also been designed as an extensive support base for future experimental systems, and includes a wiring harness leading into the suit as well as a sealed compartment for supporting electronics. This paper reviews the design of the MARS Suit, and details the current status of the development process for the MX-1 prototype unit. Plans are also presented for future testing with the MX-1, including verification of suit characteristics and biomedical data collection.