The in-flight urine collection absorber (IUCA) is a Johnson Space Center (JSC) breakthrough. It features a lightweight, compact design and is easy to use for collection of urine samples by male and female space shuttle crewmembers. The IUCA is superior to currently available hardware for flight urine-sampling protocols that do not require measurement of sample volumes. In addition, its lightweight design makes it desirable for space flight, where weight is a prime concern. Its utility has been confirmed in tests employing stable isotopes (oxygen-18 and deuterium) conducted at JSC. These tests showed that the IUCA, which can be placed in either male or female urine-collection funnels of the shuttle-waste-collection system, outperforms the standard urine collection device (UCD). Although there is no apparent commercial use at this time, the IUCA will benefit the space program by increasing capabilities for research in life sciences research capabilities.
On shuttle missions, collection of urine by use of UCDs has typically been restricted to male crewmembers. In order to collect samples from female crewmembers, it has been necessary to add flight hardware — a urine-monitoring system. This system was infrequently manifested on flights because of its considerable size and weight. Although the UCDs typically employed on the shuttle are cumbersome and are susceptible to leakage, they continue to be used to satisfy the urine-collection requirements of many flight experiments.
While many scientific protocols require information on urine volume, experiments in which stable isotopes are used typically rely on the ratio between concentrations of two compounds in urine; hence, urine-volume data are not required. While recent modifications have improved UCD function, constraints on volume and weight of equipment carried aboard the spacecraft limit space for storage of both empty and filled UCDs, and this limitation profoundly affects missions of any duration. Thus, identifying a means of collecting small urine samples from male and female crewmembers that required minimal volume and weight became a critical concern for JSC scientists.
The IUCA addresses this concern for urine-volume-independent studies. Prototype IUCA units were developed to collect small samples during flight. Each unit has a conical shape and an area ≈75 cm2. It was built from a material that is known to absorb 20.4 g of water per 100 cm2 of area. Its assembly weighs ≈20 g empty and 35 g full, as compared, to the UCD assembly, which weighs 65 g empty and can weigh from 300 to 500 g when full. The IUCA is placed in either a male or female urine-collection funnel of the shuttle-waste-control system (WCS). As a crewmember voids, the vortex action created by the shuttle vacuum system causes urine to saturate the IUCA. Upon completion of the void, the IUCA is removed from the WCS, placed in two zipper-locked bags, and stored in an absorber containment bag for return. The prototype was tested several times for volume recovery by use of a WCS mock-up in Building 5 at JSC. However, due to gravitational effects, results were inconclusive. Flight safety testing was completed, and the prototype units were subsequently certified for use in flight.
Preliminary studies were performed at JSC to evaluate the effect of the absorbent paper on the analysis of deuterium and oxygen-18 — two isotopes currently used to determine energy expenditure, water metabolism, and body composition in flight. Data obtained by use of the absorbent paper were identical to those obtained in sampling by use of conventional methods.
The IUCA will benefit the space program for which it was intended, where it can advance life sciences research by making it easy for all crewmembers to collect urine samples. While its compact nature assures compliance with shuttle mission requirements, its advanced design will prove equally adaptable to the International Space Station and to future long-duration space missions.
This work was done by Scott Smith and Helen Lane of Johnson Space Center and Janis Davis-Street and Jeannie Nillen of Lockheed Martin Engineering & Science. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Bio-Medical category. MSC-22748