Marc's note: Once again the Delta IV launch was scrubbed at the last second due to a technical issue. No new launch date has been set and with Atlantis set to land on Wednesday the Delta IV launch will have to be later in the week.

ULA And USAF Scrubbed -- Rescheduled Again!, SatNews

"The next launch attempt has been set for Monday, May 24, with a launch window of 11:13-11:31 p.m. EDT. The weather forecast calls for an 80 percent chance of acceptable weather during the launch window."

Delta 4 Poised to Launch with Next Generation GPS Satellite, Ken Kremer

"The launch of a Delta 4 rocket carrying the first in a new series of next generation GPS satellites has been rescheduled for Sunday night (May 23) at 11:17 PM EDT from Cape Canaveral, Florida after the countdown was halted barely 4 minutes prior to liftoff, shortly before midnight on Friday (May 21). The last minute countdown scrub was called after loss of "the telemetry signal between the GPS and the satellite ground support equipment," according to a statement issued by the Air Force and United Launch Alliance (ULA)."