Live at the Cape: Atlas V Counting Down

A United Launch Alliance Atlas V rocket is counting down to an 8:31 p.m. liftoff from Cape Canaveral Air Force Station.

Despite the overcast skies currently covering the Cape, Air Force forecasters expect a 70-percent chance of weather good enough for launch.

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

The 15h flight of an Atlas V will send an advanced military communications satellite into orbit 22,300 miles above Earth in about 15 minutes.

The Wideband Global SATCOM, or WGS, spacecraft would be the second to blast off from Launch Complex 41 at Cape Canaveral Air Force Station. It is intended to support troops serving in Iraq, Afghanistan and Southeast Asia.

The satellite is scheduled to separate from the Centaur upper stage about 31 minutes into the flight.

Early powering of the rocket, flight control system tests and preparation for fueling have proceeded normally.

Fueling of the booster and Centaur upper stage is scheduled to start around 6:30 p.m.

It was during that fueling process on March 17 that a leaking Centaur oxidizer valve was discovered, forcing a scrub of the mission's first launch attempt.

The valve was replaced and passed initial leak checks. The loading of super-cold liquid oxygen tonight is the valve's next test.

Check back here for updates throughout the countdown, and sign up for text message alerts in the box on the right side of the page.

A launch webcast will begin about 25 minutes before liftoff.

Mariners are advised to stay out of the designated launch hazard area off the coast between 6:30 p.m. and 10:30 p.m., or face fines of up to $50,000.

Take a look at this ULA mission booklet for more background on the launch.

And here's a ULA product sheet with more information on the Atlas V.

Here's the most recent weather forecast.