Big Day: Discovery to Pad, Rocket To Space

It's going to be an exciting day on Cape Canaveral for space fans, and you can watch it unfold here on The Flame Trench.

At 7:45 p.m., a United Launch Alliance Delta 4 Heavy rocket - the most powerful of America's unmanned launch vehicles - is expected to blast off from Cape Canaveral Air Force Station's Launch Complex 37.

This morning, starting at 4 a.m., space shuttle Discovery is scheduled to begin a slow, six-hour ride from the Vehicle Assembly Building to its seaside launch pad at Kennedy Space Center.

You can track the shuttle's early progress by refreshing the upper left image above. After NASA TV begins live coverage of the rollout at 6:30 a.m., click on the upper right image to launch a NASA TV viewer.

Discovery will be positioned for a targeted Feb. 12 blast off to start a 14-day mission to the International Space Station.

A six-million pound transporter rolling on four giant, double-tracked "crawlers" will carry the shuttle and its mobile launcher platform - an 11-million pound load - from the the 52-story Vehicle Assembly Building.

Traveling at a pace of about 1 mph, the 3.4-mile journey to launch pad 39A is expected to take roughly six hours. At the pad, Discovery's mobile launcher platform will be rested upon six 22-foot-tall pedestals.

The shuttle's rollout comes a few days before its cargo - a 31,000 pound girder that will complete the station's backbone - is installed in the orbiter's payload bay, and five days before the mission's crew arrives at KSC for pre-launch training on Monday.

Tonight's launch of a secret National Reconnaissance Office payload was delayed from Tuesday after inspectors discovered damage to foam insulation on an access door between the rocket's first and second stages.

"This was a very minor issue," said ULA spokesman Mike Rein. "We expect to have a good launch attempt today."

It would be the first unmanned launch from the Cape since last June, and only the third by a Delta 4 Heavy, whose first stage consists of three common core boosters strapped together to lift heavy payloads.

Forecasters on Tuesday predicted a 90 percent chance of favorable weather during the four-hour launch window, which opens with the targeted launch time.

ULA is expected to roll back the rocket's mobile service tower after 8 a.m.

We'll webcast ULA's live launch coverage starting 25 minutes before the launch. The coverage will end within 10 minutes of the flight when the payload fairing separates, a move intended to conceal the classified payload and its final orbit.

IMAGE NOTE: In November 2007, a Delta IV Heavy has completed rollout to Launch Complex 37 before its first operational flight. Photo credit: ULA/Carleton Bailie.