The launch of Space Shuttle Atlantis from pad 39B was postponed today for at least 24h because of an issue with the Shuttle's number one fuel cell.
A short, a spike and drop in voltage, in the fuel cell's coolant motor was seen shortly after the cell was activated. NASA's Mission Management Team is scheduled to meet at 1700GMT to consider the situation. An announcement about the Shuttle's status will be made shortly after the meeting.

On 5 August NASA's shuttle launch director Mike Leinbach was upbeat about the condition of the Shuttle stack, he said, "the countdown is going extremely well, we are not tracking any issues." Even if the fuel cell's problem is corrected NASA's launch weather officer Kathy Winters has said there is a 30% chance of showers and cumulus clouds in the Kennedy Space Center (KSC) area stopping the launch tomorrow. NASA could launch Atlantis on 8 August but if it does not its next launch window is 26 October, unless it alters its ascent lighting condition rules for imaging the external tank foam debris and aims for an earlier, possibly late September, date.

Due to problems of lightning, hail and rain for the Shuttle during its ascent, launch rules prohibit a lift off if clouds, known to contain electrical charge or ice particles, are within 20km (10.8nm) of KSC.
Atlantis's flight, STS-115, is an 11-day mission at the International Space Station assembling the P3/P4 trusses with three extra-vehicular activities for the station's new solar arrays.