Live at Cape: Atlas V Monitoring Winds, Valve

Blogger update, 6:14 p.m.: The liquid oxygen vent valve issue has been cleared for operation in a "secondary" mode after a successful retest.

The countdown to an 8:31 p.m. launch of a United Launch Alliance Atlas V rocket carrying military communications satellite has entered a planned 30-minute hold at T minus two hours.

Gusting winds are being monitored near Cape Canaveral Air Force Station's Launch Complex 41, but they are expected to subside after sunset and not present an issue.

Technicians are also conducting a second manual retest of a liquid oxygen vent valve on the Atlas booster that showed higher than normal vent rate in testing.

Launch managers said tests did not violate any parameters, but warranted a retest. After the first test continued to show the slightly "out-of-family" rate, a second test was ordered.

The valve is not the same one that scrubbed a first launch attempt March 17, which was on the upper stage.

Fueling of the first stage booster and Centaur upper stage scheduled to start around 6:30 p.m., after personnel are cleared from the pad.

A second 10-minute hold is scheduled four minutes before liftoff.

The launch window extends unitl 9:33 p.m.