NASA's Space Shuttle Endeavour Set for Evening Launch

NASA's shuttle Endeavour is poised to rocket into space this evening carrying six spaceflyers and teacher-turned-astronaut Barbara Morgan towards the International Space Station (ISS).

The space shuttle and its STS-118 crew are set to launch spaceward at 6:36 p.m. EDT (2236 GMT), with weather forecasts promising an 80 percent chance of favorable liftoff conditions.

"It looks like we have a very good vehicle on the pad," said NASA's launch integration manager LeRoy Cain. "The crew is ready. The team is ready."

In addition to Morgan, Endeavour will ferry shuttle commander Scott Kelly, pilot Charlie Hobaugh and mission specialists Tracy Caldwell, Rick Mastracchio, Alvin Drew, Jr. and Dave Williams - of the Canadian Space Agency - towards the ISS.

The astronauts plan to haul 5,000 pounds (2,267 kilograms) of cargo, a loaded spare parts platform and a new starboard-side girder to the ISS during their planned 11-day mission. The spaceflight could be extended three extra days if a new station-to-shuttle power transfer system aboard Endeavour performs as expected.

Endeavour's planned launch will mark the orbiter's return to flight status after nearly five years following a major overhaul.

"The folks that have worked on Endeavour are just feeling super right now," NASA launch director Mike Leinbach has said. "They are just ecstatic at having their ship so close to launch."

NASA's STS-118 mission is the agency's second shuttle flight in a turbulent year that has included a now-former astronaut's arrest and recent allegations of intoxicated spaceflyers allowed to fly on two occasions. ?

Launch day at last

For one Endeavour astronaut, today's launch day has been a long time coming.

Morgan, a former McCall, Idaho schoolteacher, has waited and worked through 22 years and two shuttle accidents for her planned evening launch aboard Endeavor. She first joined NASA in 1985 as the backup for New Hampshire high school teacher Christa McAuliffe, the first Teacher in Space who died with six other astronauts during the 1986 Challenger tragedy.

"I see this more of a continuation," Morgan said of her flight as it relates to McAuliffe's. "I think the great thing about it is that people will be thinking about Challenger and thinking about all the hard work that lots of folks, over many years, have done to continue their mission."

NASA called Morgan back into its spaceflying fold in 1998, this time as a full-fledged educator astronaut and mission specialist. She was assigned to Endeavour's STS-118 flight in 2002 after training to wield its robotic arm and speak for Mission Control as spacecraft communicator, or CAPCOM, but had to stand down until NASA's return to flight following the 2003 Columbia accident.

"It is great to see Barbara up there ready to fly," NASA shuttle program manager Wayne Hale said before today's launch attempt. "She's been working for a long time to have her time, her day on orbit."

Morgan will sit in the middle seat of Endeavour's middeck, flanked by Williams and Drew.

"I'm certainly going to squeeze the life out of her once we get to MECO and on orbit," Caldwell said of Morgan, referring to Endeavour's planned main engine cut-off (MECO) at the end of launch.

Space station assembly

Endeavour's STS-118 mission is NASA's second shuttle flight dedicated to ISS construction this year and features up to four spacewalks to attach the new Starboard 5 (S5) truss and other hardware to the station's exterior.

A small spacer truss, S5 will serve as the bridge between the stations newly-installed starboard solar arrays and a new pair of solar wings set to launch next year. Endeavour's crew will also deliver an external spare parts platform for the ISS and replace a broken gyroscope in the outpost's U.S. attitude control system.

"I think as an engineering accomplishment I think it's incredibly complicated," Mastracchio said of the ISS, adding so many of its components are built among many nations without ever seeing each one another before flight. "I don't know about you, but that is amazing to me."

NASA is broadcasting the launch of space shuttle Endeavour live on NASA TV. Click here for STS-118 mission updates and SPACE.com's NASA TV feed.

• VIDEO: Teaching the Future: Teacher-Astronaut Barbara Morgan
• VIDEO: Endeavour's STS-118 Launch Animation
• Complete Space Shuttle Mission Coverage