The weather forecast was dramatically more favorable one week after Tropical Storm Ernesto swept across Florida and no technical problems have been detected in the orbiter, NASA officials said Tuesday.

"The countdown is going extremely well," shuttle launch manager Mike Leinbach told reporters.

"In summary we're not tracking any issue right now, either on the vehicle or the ground site that prevent us from tanking tomorrow and go for launch at 12:29 (1629 GMT) tomorrow, so we're feeling good," he said.

The most recent forecast shows a 70 percent chance that the weather will be good, down slightly from the 80 percent chance given on Monday.

"The weather forecast remains very good ... and we have not heard of any technical issues" that could delay the launch, said Kelly Humphries, a NASA spokesman.

The National Aeronautics and Space Administration is eager to launch Atlantis on the first ISS construction mission since in nearly four years, as the 2003 Columbia shuttle disaster shifted the focus on improving flight safety.

If the weather deteriorates again or if technical issues arise, the shuttle has two more days to attempt to launch, Thursday and Friday. Failing to launch this week could delay the Atlantis mission until late October.

NASA wants to undertake 16 shuttle missions to complete the complex assembly of the half-finished ISS by 2010, when the three-shuttle fleet is set to retire.

After space shuttle Discovery returned safely in July from a second post-Columbia mission aimed at improving safety, NASA declared it was ready to resume construction of the ISS, which is a central part of US ambitions to fly humans to Mars.

Atlantis will bring a new 16-tonne segment with two huge solar panels that will double the station's ability to produce power from sunlight and ultimately provide one-fourth of the completed ISS's power.

Three lengthy spacewalks are planned to install the solar arrays, which are 73 meters (240 feet) long when unfurled.

Officials said it will be the most complex work ever undertaken at the nearly eight-year-old space station and that the next few missions will only get harder.

"We are into the heart of the station assembly and we certainly have our fingers crossed that things are going to go very well," shuttle program manager Wayne Hale told reporters Monday.

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

During their 11-day mission, the six shuttle astronauts will also use a robotic arm to scan the orbiter's heat shield for potential damage from debris falling off the external fuel tank during liftoff.

The safety check has become routine since Columbia was struck by foam that peeled off from its fuel tank during liftoff, eventually causing the shuttle to disintegrate as it returned to Earth in February 2003 with seven astronauts aboard.

The concern over debris has driven NASA to favor daytime launches that allow it to take pictures of the liftoff to detect any foam loss. The requirement limits the available launch dates and if Atlantis does not fly this week it will not be able to launch until October 26 and 27.

But Hale said he had tasked engineers and safety officials to review the requirement. If the restriction is lifted, the shuttle could schedule launch attempts in late September or early October, he said.

The Atlantis crew is commanded by Brent Jett and co-piloted by Chris Ferguson. The four mission specialists are Daniel Burbank, Heide Stefanyshyn-Piper, Joe Tanner and Canadian Steve MacLean of the Canadian Space Agency.

Related Links
Shuttle and Stations at NASA
Space Shuttle News at Space-Travel.Com

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