NASA controllers said the space shuttle Discovery is go-for-launch for tonight's mission to the International Space Station. Discovery is set to light up the sky around Florida's Kennedy Space Center early Tuesday with a 1:36 a.m. launch.

As of late Sunday, NASA said there were no issues that would prevent an on-time liftoff.

"I'm really pleased to report that launch countdown activities are proceeding normally and we are working no issues," said launch director Pete Nickolenko, in a statement. He added that there are four launch windows available to Discovery in the next five days and that it's 96% certain that the spacecraft will be able to take off during one of them.

The COLBERT treadmill is among the numerous pieces of equipment that will be on board Discovery when it lifts off. The exercise device is named after comedian Stephen Colbert. Discovery also will carry to the ISS the Leonardo supply module, which features refrigerator-size storage racks.

STS-128, as the mission is called, will be commanded by veteran astronaut Rick "C.J." Sturckow. Joining him are six other space goers, including pilot Kevin Ford and mission specialists Patrick Forester, Jose Hernandez, Nicole Stott, and John Olivas. Christer Fuglesang will represent his native Sweden on the mission.

The crew arrived at Kennedy last week for prelaunch preparations.

"It's great to be here for the launch," said Sturckow. "We've been studying and training hard, and we're ready to go accomplish this mission." NASA officials anticipate a successful launch.

"I can't say enough about the quality of the review we had over the past day and a half," said Bill Gerstenmaier, associate administrator for Space Operations, at a news conference last week. "It was a very effective review; I think we're ready to go fly," he said.

Gerstenmaier added that preparations were a group effort.

"It's a real tribute to be here with the team that's done a great job with engineering, the Kennedy team that's gotten us this far in the process," he said.