NASA cleared the space shuttle Atlantis to launch toward the International Space Station on Monday on a delivery mission.
Atlantis is set to lift off at 2:28 p.m. ET on Monday from Launch Pad 39A at Kennedy Space Center in Florida to carry six astronauts and two cases of large spare parts to the station.
The weather outlook is optimistic for Monday, with a 90 percent chance of clear skies predicted.
"Overall Monday is looking good, so hopefully we'll go off on Monday," weather officer Kathy Winters said during a Saturday briefing.
An Atlas 5 unmanned rocket slated to launch from the nearby Cape Canaveral Air Force Station early Saturday stood down at the last minute for crews to investigate a power glitch. The cancellation frees up the schedule for Atlantis to proceed as planned, and Atlas managers will aim to try again to launch after Atlantis lifts off.
"They'll be ready to go when they're ready," said Mike Moses, chair of Atlantis' mission management team. "We fully expect we'll be out of here come Monday and the range will be clear for them to try again."
The mission management team met Saturday morning to discuss the status of the mission, and there was "a unanimous vote to proceed with the launch countdown," Moses said.
The shuttle's countdown toward liftoff began on Friday at 1 p.m. ET. So far, everything's gone smoothly.
"We're one day into Atlantis' countdown and I'm happy to report we're right on the money," said launch director Mike Leinbach.
One issue NASA is monitoring is a broken urine recycling system on the space station, which helps to process waste water and turn it back into usable drinking water. A mechanism in the machine failed, and managers decided to ship the broken instrument back on Atlantis to be analyzed on the ground.
Meanwhile, the station is left with a limited ability to recycle water, although the station residents should be able to manage by using the other facilities onboard. Ultimately, the malfunction shouldn't present a problem for the incoming shuttle crew.
"There's no impact," Moses said. "Bottom line, they're in pretty good shape."
Commander Charlie Hobaugh plans to lead the six-member STS-129 crew on the 11-day space trip. The mission will feature three spacewalks to attach the cases of spare parts to the station.