Delta 4 launch slides to May 24

3 p.m. update: The team has secured May 24 on the range. Launch time is between 6:11 p.m. and 7:11 p.m. The issue is with actuators that help control steering of the RS-68 engine in flight. Boeing is removing and replacing them as a precaution after similar actuators showed problems during acceptance testing. A side note: Boeing has until May 30 to get the GOES-N off the ground here. Otherwise, another Delta 4 mission from Vandenberg Air Force Base (to launch a classified spy spacecraft for the National Reconnaissance Office) takes precedence. The GOES-N team would stand down until after the NRO launch, now set for June 27.

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The return to flight of the Delta 4 rocket looks to be sliding four to five days on the calendar to no earlier than May 24. A technical issue with the rocket's first stage is the culprit, and a final decision about the delay and the new launch date won't be made until sometime later today.

The Delta 4 last flew in December 2004, when the first-ever heavy model of the Boeing rocket suffered first-stage performance degradation and left its payload about 10,000 miles short of its intended orbit. A string of technical problems and a lengthy strike by Boeing machinists have contributed to the lingering grounding.

NASA's George Diller says the mission, to launch a GOES-N weather satellite, should be reset for either May 24 or May 25. We'll have more details later today once a new date and time are approved. We'll also get more details on the technical concern.