The technical objective of this effort is to develop a flight-ready miniaturized degasser system that includes all support hardware needed to operate on-orbit with minimal crew interaction. The degasser assembly utilizes hydrophilic and hydrophobic membranes under low pressure to separate gas bubbles from a fluid line. The key properties of the membranes are bubble point and water intrusion pressure, respectively. The degasser was fully characterized for pressure-versus-flow-rate dependence, bubble point, water intrusion pressure, and typical contamination rate. Three different sizes of degassers were developed and manufactured (see figure 1). The increase in degasser size offers an increasing life (time to contamination). The table shows a summary of the specifications for the three different degasser sizes.

Figure 1. The Three Degasser Assembly Sizes, Three Each Shown

A prototype system was built that combines the degasser with the support electronics and mechanical components necessary to circulate the fluid through the degasser assembly while monitoring system pressure and possible system failures. Priming and recirculation protocols are part of the standard operations and can be accessed from the top panel of the system (see figure 2). Recirculation is also automated by the system if bubbles are detected in the outlet fluid line of the degasser.

The SPAFSS Integrated System has the potential for drastically reducing crew time on orbit for plant growth experiment functions such as root module and reservoir priming. A manual priming procedure could be replaced with the use of the SPAFSS Integrated System. The system may also be used for a variety of other experimental systems requiring a bubble-free fluid line because the flow rate of the system is adjustable to 50, 100, 150, and 200 millimeters per minute (ml/min) and operable pressure ranges are up to 8 psi.

A flight-ready SPAFSS Integrated System is currently under development. Capabilities are being added to the system to detect system flow and add redundancy to the bubble detection system. The SPAFSS Integrated System will be designed to fly and operate in the Space Shuttle Middeck and in the International Space Station (ISS). The SPAFSS Integrated System will be one-fourth the size of a Standard Middeck Locker and will be transported in a half-size cargo transfer bag. Power consumption is approximately 12 watts and the system weight is approximately 11 pounds.

Contact: Dr. J.C. Sager (John.Sager-1@ksc.nasa.gov), YA-E4, (321) 476-4270
Participating Organization: Orbital Technologies Corporation (J. Maas)

Figure 2. Prototype SPAFSS Integrated System