The STS-118 crew is at Launch Pad 39A. A short elevator ride to the 195-foot level brought the astronauts to the White Room where one by one each crewmember is assisted by NASA's closeout crew to prepare to board the shuttle.
Their flight suits are checked and an orange glow stick was tucked into the pocket of each suit for safety.
Countdown is proceeding smoothly, and there's only a 20 percent chance of weather prohibiting a liftoff at 6:36 p.m. EDT.
Mission STS-118 will be the first for Mission Specialist Barbara Morgan, the teacher-turned-astronaut whose association with NASA began more than 20 years ago. First Lady Laura Bush called Morgan Tuesday morning to offer congratulations "one schoolteacher to another," and to thank her for her commitment to the space program and to education.
The 22nd flight to the International Space Station, STS-118 will be the first flight for Endeavour since 2002. Launch remains on target for Aug. 8 at 6:36 p.m. EDT.
Explore further: Life 'not as we know it' possible on Saturn's moon Titan