Shuttle Discovery STS-133 Mission Commander Steve Lindsey gives a thumbs up during a practice crew walkout at Kennedy Space Center, Cape Canaveral, Florida, USA 15 October 2010. The crew of six is headed to launch pad 39A for a mock countdown that completes the three day Terminal Countdown Demonstration Test. Shuttle Discovery is being prepared for what is to be it's final mission to the International Space Station, with launch scheduled for no earlier than 01 November 2010.