Liftoff! Space Shuttle Atlantis Launches on ISS Construction Mission

NASA's space shuttle Atlantis roars off the launch pad for a rendezvous with the International Space Station on mission STS-115. In the foreground is the countdown clock, marking launch and mission-elapsed time, on the grounds of the NASA News Center. CREDIT: NASA/Webb Dillard.

This story was updated at 12:05 a.m. EDT.

CAPE CANAVERAL, Fla. - Despite a beginning beleaguered by lightning, storms and a last minute glitches, NASA's shuttle Atlantis rocketed spaceward Saturday with six astronauts and the future of the International Space Station (ISS) aboard.

Atlantis launched at 11:14:55 a.m. EDT (1514:55 GMT) from Pad 39B here at NASA's Kennedy Space Center (KSC) on the last day of its launch window, which was stretched to the tilt.

"Well, Brent, it looks like you're long wait is over," NASA launch director Michael Leinbach told Atlantis commander Brent Jett just before liftoff. "We wish you all the best luck in the world, Godspeed and we'll see you in about two weeks."

"Thanks Mike, we appreciate those words and the effort to make this launch window," Jett said, adding that his crew has waited for four years and through two test missions for their chance to resume ISS construction. "We're ready to get to work."

Shuttle pilot Chris Ferguson and mission specialists Joseph Tanner, Daniel Burbank, Heidemarie Stefanyshyn-Piper and Steven MacLean - of the Canadian Space Agency - rode Atlantis into orbit with Jett.

Atlantis' astronaut crew are hauling a 17.5-ton load of trusses and wing-like solar arrays to the ISS to mark NASA's first ISS construction flight since the 2003 Columbia accident.

"We're confident that over the next few weeks, and few years for that matter, NASA is going to prove to our nation, our partners and our friends around the worth that it was worth the wait and the sacrifice," Jett said of resuming ISS construction.

Aboard the ISS, Expedition 13 commander Pavel Vinogradov and flight engineers Jeffrey Williams and Thomas Reiter are awaiting the shuttle's arrival. The successful space shot marked the 116^th shuttle launch for NASA and Atlantis' 27^th trip into Earth orbit.

Conquering delays

Today's liftoff comes after a series of delays for Atlantis, the last of which culminated in the failure Friday of one of four liquid hydrogen fuel gauge sensors in the orbiter's external tank. That sensor worked perfectly during today's liftoff, NASA officials said.

Other delays were prompted by a lightning strike to the shuttle's launch pad, weather threats from a tropical depression and a power glitch in a pump motor that helps cool one of the spacecraft's three vital fuel cells. The fuel cell issue led shuttle officials to scrub a Sept. 6 launch attempt, but was not in violation of any flight rules.

A busy mission lies ahead for STS-115 astronauts, beginning with orbital photography of Atlantis' external tank - shed after reaching orbit - as it fell back toward Earth. A heat shield inspection is set for tomorrow, followed by a Monday docking at the ISS and back-to-back spacewalks.

"This is probably one of the busiest first five days we've done in a very long time," John McCullogh, the lead ISS flight director for Atlantis' mission, told SPACE.com.

Orbital construction zone

The $371.8 million cargo aboard Atlantis is the first of many elements - among them additional power segments, Russian modules and international laboratories - slated to launch toward the ISS. The first ISS module, Russia's Zarya, launched in 1998, with the last major addition arriving during NASA's STS-113 mission aboard Endeavour in late 2002.

"Clearly we are into the heart of the assembly of the International Space Station," said Wayne Hale, NASA's space shuttle program manager, of the STS-115 mission, adding that its refreshing to once more engage in orbital construction. "We're flying the shuttle for a purpose, to carry a payload, to create this marvelous research outpost [so] that we have a toehold in space. It is really the purpose for what we are here for."

Once complete, the space station will sport four wing-like solar arrays, weigh a whopping one million pounds and rival a five-bedroom home in living space, NASA officials have said. Measured end to end, the orbital laboratory will run about 354 feet, making it the longest human-built structure ever to fly in space.

"Future expansion of the station hinges on the ability to power that expansion," NASA astronaut Doug Wheelock, who will help deliver a critical connecting node for new ISS modules next year during Atlantis' STS-120 mission, told SPACE.com. "So this is really a critical piece in the flow."

Completion of the $100 billion space station stalled as NASA made shuttle safety enhancements and launched two test flights to recover from the loss of Columbia and its seven-astronaut crew. NASA is now aiming to complete the station with 15 partner nations - which include Canada - by September 2010, when the three remaining shuttles are to be retired.

"We're pleased to be where we are right now, "said Beno?t Marcotte, station program director for the Canadian Space Agency which provided the ISS robotic arm, before today's launch. "We're pleased to see the sequence starting again."

More than 140 spacewalks - three of them planned for STS-115 - will have been staged to complete the ISS, NASA officials said, adding that one-fourth of the agency's shuttle flights will have been dedicated to building the orbital laboratory.

"Clearly these are the most complicated spacewalk and assembly tasks that have ever been done before," Hale said.

From NASA's perspective, completing the ISS is vital to the U.S. goals of returning astronauts to the Moon and pushing human explorers further into space.

"What we're doing in building the space station is really preparing ourselves for Mars, and of course the Moon," NASA astronaut Michael Fincke, who served a six-month term aboard the ISS during 2004's Expedition 9 ISS mission, told SPACE.com. "I don't think personally you can skip any of the steps along the way."

Fincke added that there is another benefit from the ISS construction effort aside from the exploration of space. With 16 countries working to complete the massive space station, the project has proved an object lesson in international cooperation.

"I always say that it's great when human beings on this planet work constructively and not destructively," Fincke said.

• VIDEO: First Tasks of NASA's STS-115 Mission
• Gallery: Prepping Atlantis
• Complete Space Shuttle Mission Coverage
• NASA's STS-115: Shuttle Atlantis to Jump Start ISS Construction
• The Great Space Quiz: Space Shuttle Countdown
• Complete Coverage: ISS Expedition 13