In less than two hours, NASA's Space Shuttle Discovery is scheduled to make its last trip into low Earth orbit. Discovery will be traveling to the International Space Station, carrying a large module packed with supplies and critical spare parts, as well as a robotic assistant named Robonaut 2. With the entire Space Shuttle program scheduled for mandatory retirement this year, Discovery is the most-flown spacecraft in history, traveling 143 million miles (230 million kilometers) over the course of its 39 missions since 1984, and spending nearly a full year in orbit. Gathered here are images of Discovery, its crew, and support staff from the past several months, while the spacecraft was being prepared for today's launch. This mission, STS-133, is scheduled for liftoff at 4:50 p.m Eastern Time.