The Space Shuttle Discovery is on track for a Wednesday launch, with a 30 percent chance of weather causing a further delay.
Technicians are currently inspecting the external tank liquid oxygen feed line, according to NASA. Onboard and ground communications will be activated this afternoon. Preparations are being made to move the rotating service structure – which protects the shuttle and allows the crew to load items onboard – this evening.
"There is excitement in the air," NASA test director Steve Payne said in a statement. "People are putting their game faces on."
The shuttle was initially scheduled to launch on Monday, but helium and nitrogen leaks in the pressurization portion of space shuttle pushed that to Tuesday. When repairs related to those leaks lasted longer than expected, NASA again delayed the launch to Wednesday at 3:52pm Eastern time.
The shuttle will launch from the Kennedy Space Center in Cape Canaveral, Fla. At this point, there is a 30 percent chance of weather prohibiting launch, but there "are no technical issues that stand in the way of launch," NASA said on its Twitter feed.
There is a chance of isolated showers and a cloud deck at 3,000 feet could be of some concern, but the outlook is largely positive, NASA officials said Tuesday. If the launch is delayed another 24 hours, the weather forecast for Thursday is not as rosy; the area could get up to an inch of rain, giving NASA a 70 percent chance of weather prohibiting a Thursday launch.
"Overall tomorrow looks like a good day, especially when you compare it to Thursday," a NASA official said during a press briefing.
This mission is the last spaceflight for Discovery, NASA's oldest active shuttle. Its history includes deployment of NASA's Hubble Space Telescope and two successful return-to-flight missions, STS-26 and STS-114. After this mission, the shuttle orbiters will be donated to various museums, but NASA has not yet determined which organizations will receive them, Payne said.
If all goes according to plan, live coverage will begin on NASA TV at 6:25am Eastern time as crew members start fueling Discovery. Official launch coverage begins at 10:30am, with actual launch set for 3:52pm.