Proceedings Article | 15 April 2016
Lenore Rasmussen, Eric Sandberg, Leila Albers, Simone Rodriguez, Charles Gentile, Lewis Meixler, George Ascione, Robert Hitchner, James Taylor, Dan Hoffman, David Cylinder, Leon Moy, Patrick Mark, Daniel Prillaman, Robert Nordarse, Michael Menegus, Jo Ann Ratto, Christopher Thellen, Danielle Froio, Cosme Furlong, Payam Razavi, Logan Valenza, Surbhi Hablani, Tyler Fuerst, Sergio Gallucci, Whitney Blocher, Stephanie Liffland
KEYWORDS: Electroactive polymers, Space robots, Artificial muscles, Robotics, Resistance, Ionizing radiation, Tissues, Polymers, Actuators, Robots, Gamma radiation, Radium, Matrices, Glasses
In anticipation of deep space travel, new materials are being explored to assist and relieve humans in dangerous environments, such as high radiation, extreme temperature, and extreme pressure. Ras Labs Synthetic Muscle – electroactive polymers (EAPs) that contract and expand at low voltages – which mimic the unique gentle-yet-strong nature of human tissue, is a potential asset to manned space travel through protective gear and human assist robotics and for unmanned space exploration through deep space. Generation 3 Synthetic Muscle was proven to be resistant to extreme temperatures, and there were indications that these materials may also be radiation resistant. The purpose of the Ras Labs-CASIS-ISS Experiment is to test the radiation resistivity of the third and fourth generation of these EAPs, as well as to make them even more radiation resistant or radiation hardened. On Earth, exposure of the Generation 3 and Generation 4 EAPs to a Cs-137 radiation source for 47.8 hours with a total dose of 305.931 kRad of gamma radiation was performed at the US Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) at Princeton University, followed by pH, peroxide, Shore Hardness Durometry, and electroactivity testing to determine the inherent radiation resistivity of these contractile EAPs and to determine whether the EAPs could be made even more radiation resistant through the application of appropriate additives and coatings. The on Earth preliminary tests determined that selected Ras Labs EAPs were not only inherently radiation resistant, but with the appropriate coatings and additives, could be made even more radiation resistant. Gforce testing to over 10 G’s was performed at US Army’s ARDEC Labs, with excellent results, in preparation for space flight to the International Space Station National Laboratory (ISS-NL). Selected samples of Generation 3 and Generation 4 Synthetic Muscle™, with various additives and coatings, were launched to the ISS-NL on April, 14 2015 on the SpaceX-6 payload, and will return to Earth in 2016. The most significant change from the on Earth radiation exposure was color change in the irradiated EAP samples, which in polymers can be indicative of accelerated aging. There was visible yellowing in the irradiated samples compared to the control samples, which were not irradiated and were clear and colorless. While the Synthetic Muscle Experiment is in orbit on the ISS-NL, photo events occur every 4 to 6 weeks to observe any changes, such as color, in the samples. The bulk of the testing will occur when these EAP samples return back to Earth, and will be compared to the duplicate experiment that remains on Earth (the control experiment). Smart electroactive polymer based materials and actuators promise to transform prostheses and robots, allowing for the treatment, reduction, and prevention of debilitating injury and fatalities, and to further our exploration by land, sea, air, and space.
