Volume Sensor for Flexible Fluid Reservoirs in Microgravity

The Advanced Space Suit carries consumable cooling water maintained at ambient pressure within a soft-walled, flexible reservoir. To ensure uninterrupted thermal control it is critical to monitor the volume of water remaining, but no known sensor is suitable for this task. Existing measurement techniques are unacceptably sensitive to the motion and varying geometry of the reservoir in microgravity, or to electromagnetic interference within the suit environment. We have developed a simple, compact, low power sensor that accurately measures the volume of fluid in any soft-walled bladder. Our innovative sensing technique will provide an accurate measurement that is insensitive to gravity, the motion and geometry of the reservoir, the presence of air pockets, and electromagnetic interference. We will develop a fully integrated sensor system suitable for use on the Advanced Space Suit and perform functional validation and spaceflight qualification testing. The Advanced Space Suit carries consumable cooling water maintained at ambient pressure within a soft-walled, flexible reservoir. To ensure uninterrupted thermal control it is critical to monitor the volume of water remaining, but no known sensor is suitable for this task. Existing measurement techniques are unacceptably sensitive to the motion and varying geometry of the reservoir in microgravity, or to electromagnetic interference within the suit environment. We have developed a simple, compact, low power sensor that accurately measures the volume of fluid in any soft-walled bladder. Our innovative sensing technique will provide an accurate measurement that is insensitive to gravity, the motion and geometry of the reservoir, the presence of air pockets, and electromagnetic interference. The overall objective of the Phase II effort will be to develop and demonstrate a space-flight ready volume measurement system that can be readily integrated with the Feedwater Supply Assembly (FSA) within the Portable Life Support System (PLSS) on NASA’s Advanced Space Suit. Specific technical objectives will include: Develop a specification that captures NASA’s requirements for mechanical and controls integration of the sensor system with the FSA and PLSS. Develop a refined mechanical assembly and production process to seamlessly and robustly integrate the sensor with the FSA bladders. Develop, fabricate, and validate an electrical control circuit that will control the sensor and report results to the PLSS control system using commercial grade components with S-Class equivalents. Develop embedded software and calibration routines to drive the sensor controller. Fully characterize the performance of the sensor in laboratory tests. Begin the process of qualifying the sensor for flight on NASA missions by completing required testing such as electromagnetic emissions and vibration endurance. Deliver sensor prototypes to NASA for evaluation. Demonstrate the performance of the sensor on board a sub-orbital rocket flight with several minutes of micro-gravity at its apex.

The Feedwater Supply Assembly in the Advanced Space Suit is a soft-walled, flexible reservoir containing cooling water. The water is circulated through the thermal control loop and slowly consumed by evaporation at the Suit Water Membrane Evaporator, rejecting waste heat to control occupant temperature. To ensure uninterrupted thermal control and occupant survival, it is critical to monitor the remaining water volume. The sensor developed under this program will accurately monitor the remaining volume in this reservoir. This sensor will function equally well in any other flexible fluid reservoir on a space platform. This may include fuel, coolant, and cryogen storage bladders on various spacecraft, satellites, and stations. This sensor technology will meet similar bladder volume monitoring needs in other microgravity applications such as commercial spacecraft and orbital stations, along with water and fuel storage bladders used in military and recreational applications.

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