In-Situ Fabricated Space Suits for Extended Exploration and Settlement
Carlos Callejon Hierro
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Human Mars exploration will result in a demand for extravehicular activity one or two orders of magnitude beyond prior peak rates, occurring at the end of a 26-month logistics cycle. The extensive fabric “soft goods” of conventional spacesuits are subject to wear and abrasion, tend to carry dust back into the crew habitats, and replacement parts must be transported from Earth and stocked for use on need. This paper reports on the first year of an ongoing project at the University of Maryland (UMd) examining the technology of “hard suits”, in combination with recent advancements in additive manufacturing, to examine the potential for the use of hard suits in Mars exploration with on-site fabrication of replacement parts, or even entire pressure garments on need. The current focus has been on materials testing, fabrication techniques, and testing methodologies. Starting with a baseline suit kinematic configuration mirroring that of the NASA Ames AX-5 suit, the primary functional allocations of the suit elements were focused down to structural elements, bearings, and seals. Materials samples were tested to quantify design parameters for differing materials, fabrication methods, and even variations between individual machines. Bearings were fabricated with all parts or with post-fabrication insertion of steel or ceramic balls, and tested for joint torques under load and for failure loads. Seals were fabricated of elastomeric materials and tested for sealing performance and friction. Based on test results, the top candidate elements were incorporated into a prototype pressurized arm segment compatible with the UMd glove box, which was used for testing of the prototype arm segment at both 8.3 and 4.3 psid. Testing consisted of direct measurement of required movement torques through the use of a robotic arm simulator, as well as human factors testing with comparison to a standard EMU arm segment.