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.