KENNEDY SPACE CENTER, FLA. -- Inside the Vertical Processing Facility, the Chandra X-ray Observatory sits inside the payload canister, ready to be moved to Launch Pad 39B. Liftoff will take place no earlier than July 20 at 12:36 a.m. EDT aboard Space Shuttle Columbia, on mission STS-93. Chandra will allow scientists from around the world to obtain unprecedented X-ray images of exotic environments to help understand the structure and evolution of the universe. Chandra is expected to provide unique and crucial information on the nature of objects ranging from comets in our solar system to quasars at the edge of the observable universe, map the location of dark matter and help to identify it, and probe the faintest of active galaxies, allowing scientists to study not only how their energy output changes with time, but also how these objects produce their intense energy emissions in the first place. Since X-rays are absorbed by the Earth's atmosphere, space-based observatories are necessary to study these phenomena and allow scientists to analyze some of the greatest mysteries of the universe.