I am trying to determine under what conditions a fourth EVA will be conducted on STS-117. I have reviewed the
STS-117 press kit and listened to the preflight briefings. The only definitive statement was that a fourth EVA
would be conducted if the P6/2B solar array was not fully retracted by the end of EVA-3. The press kit seems
to indicate that the tasks scheduled on EVA-3 are all getaheads. However the highest priority task on EVA-3 is
to prepare S3 so that the MTS can move to WS #1. On STS-118, the MTS must be located at WS #1 so that the
SSRMS can install truss segment S5 on S4. It seems that this is not an optional task but must be completed
before STS-118 can be launched. Since there are no stage US EVA's scheduled between STS-117 and STS-118
it seems to me that this task must be done on STS-117. Does anyone have additional details on this?