This closeup shows Space Shuttle Atlantis as it begins rolling out of the Vehicle Assembly Building on its slow trek.

This closeup shows Space Shuttle Atlantis as it begins rolling out of the Vehicle Assembly Building on its slow trek to the launch pad. Below Atlantis' wings are the Tail Service Masts on the Mobile Launcher Platform. Atlantis is scheduled for launch April 4 on mission STS-110, which will install the S0 truss, the framework that eventually will hold the power and cooling systems needed for future international research laboratories on the International Space Station. The Canadarm2 robotic arm will be used exclusively to hoist the 13-ton truss from the payload bay to the Station. The S0 truss will be the first major U.S. component launched to the Station since the addition of the Quest airlock in July 2001. The four spacewalks planned for the construction will all originate from the airlock. The mission will be Atlantis' 25th trip to space