Space Shuttle Discovery, still on track for 3:51 PM EST launch, faced a few unexpected problems this morning. First, a temporary window cover fell off the shuttle and damaged two thermal tiles; an incident which provided an eerie reminder of the chunk of foam that fatally damaged Columbia. Luckily the tiles were easily replaced. Second, the fueling of the external tank began more than an hour late after a part on the launch-pad heater had to be changed.
With these two mishaps cleaned up, the only thing that can stop Discovery are thunder showers which are expected during the small window of time available for launch. Discovery has about a five minute period during which it must be launched, or it will be unable to rendezvous with the orbiting International Space Station.
Update: 1:30 PM EST: NASA calls off shuttle launch because of a faulty fuel-tank sensor
Troubles
