Cape Canavarel, Fla. ? The countdown for NASA’s return to space began Sunday amid sky-high anticipation, although Hurricane Dennis threatened to interfere with the liftoff of the first shuttle mission in more than two years.

Rian Busse, left, and Brenda Mulberry take Discovery launch T-shirts off the conveyor dryer Thursday at Space Shirts in Merritt Island, Fla. The area's 9,000 hotel rooms are all booked and T-shirts have been delivered to local shops.

At precisely 6 p.m., the multitude of countdown clocks started ticking down to a Wednesday launch of Discovery. The last time they flashed the hours, minutes and seconds remaining before a blastoff was in 2003, for Columbia’s disastrous flight.

Test director Jeff Spaulding said excitement had been “building and growing” ever since the space agency overcame fuel-tank difficulties that prompted a launch delay a few months ago.

“It’s only recently, I think, that it’s all come to fruition where we can see the light at the end of the tunnel,” Spaulding said.

“There’s some excitement for people to get back to launching again and also, I think, maybe a quiet reserve as well, just remembering where we’ve been. But we all do feel confident that we’ve done it right.”

In this image released by NASA, STS-114 astronauts pose for their group photo.

Added payload manager Scott Higginbotham: “It sure does feel good to be back in the saddle again. It’s been too long.”

The effects of Hurricane Dennis, which roared ashore on the Florida Panhandle off to the northwest, could be felt at the launch site Sunday as the sky was gray and solidly overcast.

Thunderstorms were forecast throughout the week. However, a ridge of high pressure offered hope that the storms may stay away at launch time Wednesday afternoon. Forecasters put the odds of acceptable weather at 70 percent, with conditions expected to worsen as the week wears on.