Fuel Cell problems

From The Flame Trench here:

An erratic current reading from one of Atlantis' fuel cells stopped NASA from fueling the shuttle overnight and ultimately forced postponement of today's launch. Engineers are scrambling this morning to figure out the problem in time to ready the spaceship for back-to-back launch attempts on Thursday and Friday.

Mission managers will meet later today to review engineers' progress and decide whether they can try to launch Thursday or not. Liftoff would be at 12:03 p.m. But fuel cell problems are notoriously complex and the fuel cell glitch has the potential to delay the flight until late September at the earliest.

The fuel cell problem cropped up overnight. Launch crews started to activate the fuel cells, which provide electricity for life support and other systems once the orbiter reaches space. The voltage dropped in fuel cell No. 1, an indication that the fuel cell might not be working properly. All three must work or NASA won't fly.

Mission managers, meeting at 1:45 a.m., opted not to start fueling Atlantis as scheduled at 2:30 a.m. By 4 a.m., with the problem still unsolved, they gave up on a Wednesday launch attempt and let the engineers continue their troubleshooting.

Fuel cell problems can be complicated and hard to diagnose. In the most optimistic view, the problem could be something as simple as a faulty instrument reading. In a worst case scenario, if the fuel cell or a related component is bad, NASA could be facing a rollback to the Vehicle Assembly Building.