STS-134 Pilot Greg H. Johnson prepares to board space shuttle Endeavour during the Terminal Countdown Demonstration Test TCDT.

In the White Room of Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-134 Pilot Greg H. Johnson prepares to board space shuttle Endeavour during the Terminal Countdown Demonstration Test (TCDT). Part of TCDT includes practicing the final hours of a real launch day when astronauts put on their launch-and-entry suits, ride to the pad in the Astrovan and strap into the shuttle.

Endeavour's six crew members are targeted to launch April 19 at 7:48 p.m. EDT. They will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank, additional spare parts for the Dextre robotic helper and micrometeoroid debris shields to the International Space Station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jim Grossmann