KENNEDY SPACE CENTER -- Launch director Mike Leinbach says the signature of the leak at the ground umbilical carrier plate this morning is "slightly different" than the one that scrubbed STS-127's launch attempt on Saturday. This was to be expected, as cryogenic leaks are all slightly different, he said.
This time, engineers noticed the leak before the tank topping sequences began, said Leinbach. Several cycles of clearing out the vent valve "never cleaned up" the issue, he said.
The gaseous hydrogen leak was "way out of spec" and "beyond what we felt comfortable with," he said.
Engineers have begun draining the tank -- a process that will take more than two hours. A full read out of this morning's problems will occur at 3:30 a.m. EDT.