ISS018-E-041370 (21 March 2009) --- Astronaut Sandra Magnus, STS-119 mission specialist, prepares to work with the Lab-on-a-Chip Application Development-Portable Test System (LOCAD-PTS) experiment in the Destiny laboratory while Space Shuttle Discovery remains docked with the International Space Station. LOCAD-PTS is a handheld device for rapid detection of biological and chemical substances onboard the station.