Inflatable vehicles and parachutes are two types of systems that are necessary for safe and economical operation of space vehicles in a range of NASA programs, including small spacecraft initiatives. Yet these structures are complex, creating challenges for engineers who are designing, analyzing and testing new systems. Often, the prudent engineering response is to build in more safety margin than is needed to ensure the system will not fail. New passive wireless sensors that can accurately measure the strain on parachutes and inflatable structures would enable engineers to understand the behavior of these complex systems better, allowing them to develop more accurate simulation tools and design structures that will meet mission needs with adequate safety margins without unnecessary additional weight and cost. Individually identifiable wireless sensors that can be deployed in multiple positions across a flexible structure and read by a centralized reader would enable dynamic measurement of strain during system deployment. To meet mission needs, including long storage periods prior to deployment and long use lives, passive wireless sensors (without any batteries to change) are ideal. We propose the use of innovative passive wireless surface acoustic wave (SAW) based strain sensors or sensor-tags for near real-time strain measurement in parachutes and inflatable habitats. These devices can be produced in sets of tens up to a hundred or so individually identifiable devices, that work together and can be read simultaneously by data aggregators without inter-sensor interference. The sensor-tags can be read wirelessly over a range of tens of meters or more depending on transmit power limitations and environment. Successful completion of the proposed effort will evaluate the technical feasibility of both flexible SAW strain sensors and a new type of hybrid strain sensor. The proposed work will provide a basis needed to prototype a complete strain sensor system in Phase II
The proposed passive wireless flexible strain sensors will provide distributed near-real-time data on parachutes and inflatable structures as they deploy, and over the life of the structure. Programs with inflatable vehicles and/or parachutes that could benefit from the proposed sensors include the Bloostar launch vehicle by Zero2Infinity, which uses parachutes for platform recovery on launch abort, and the Vulcan Centaur launch vehicle by ULA, for aerial recovery of the booster engines, avionics, and thrust structure after module descent.
The proposed passive wireless flexible strain sensors will likely have commercially significant terrestrial applications in areas such as instrumented clothing, and in medical fields such as orthopedics, physical therapy, prosthetics, and kinesiology. Virtual reality and gaming is also another area where gloves equipped with flexible stretch/movement sensors are an emerging product sector.