The countdown started yesterday afternoon, a couple of days later than expected. NASA spokesman Kyle Herring says seals were leaking on two pressurization systems.
"One associated with the shuttle, one associated with the ground equipment on the other side of the vehicle. All of those were resolved before we even began the countdown, and since the countdown has begun, everything has been going smoothly."
Discovery's final countdown will follow a standard template, as crew members wrap up additional training related to the delivery they'll make to the International Space Station. Herring says managers have been reflecting on this being Discovery's last hurrah in a way similar to how many people might think of their own earthbound vehicles.
"When you own a car for a number of years, you become attached to it. When it comes time to trade that vehicle in or sell it and move on to another vehicle, there is a little bit of a twinge associated with it. Even though it's a machine, it still has some sort of emotional attachment that people place on it."
Discovery is set for liftoff Wednesday afternoon at 2:52, Houston time, with a 70 percent chance of favorable weather in Florida. If it doesn't happen Wednesday, NASA says there will be other launch opportunities every day through Sunday.