Space Shuttle Atlantis Crew Practice Escape Drill

In the payload changeout room on Launch Pad 39B, STS-115 crew members look over the mission payload one more time before launch. The mission crew has been at KSC to take part in Terminal Countdown Demonstration Test activities, which include emergency egress training, a simulated launch countdown and the payload familiarization. CREDIT: NASA/Cory Huston

CAPE CANAVERAL - The Atlantis astronauts capped a practice countdown Thursday with a drill they never want to go through for real: A launch tower escape.

With the six crewmates strapped into Atlantis at Kennedy Space Center's launch pad 39B, and just four seconds remaining on countdown clocks, NASA and contractor engineers simulated a potentially dangerous main engine shutdown.

The astronauts expeditiously exited the orbiter, heading to metal baskets that would whisk them off the 36-story gantry and down to the ground in an emergency. The exercise is considered crucial in the training of any astronaut crew.

"It really exemplifies the complications that they would have to go through if there were an emergency on launch day," said NASA Test Director Jeffrey Spaulding, who orchestrated the operation from the KSC Launch Control Center.

"There's nothing like trying to do it when you have your launch-and-entry suit on and you're strapped into the vehicle," he added. "It's good training for them."

In 115 shuttle flights to date, NASA has experienced five "pad aborts" -- engine shutdowns within seconds of the ignition of the shuttle's two solid rocket boosters.

The orbiter's three liquid-fueled engines ignite 6.6 seconds prior to launch. The start-up is performed to make sure the engines are operating properly before booster ignition and liftoff.

The emergency drill is the only opportunity for the Atlantis astronauts to practice a launch tower escape prior to their planned Aug. 27 flight.

Bunched in two groups of three, the astronauts hurried across the orbiter access arm, which is a metal walkway that leads to the shuttle's side hatch. Then they crossed the 195-foot level of the gantry and climbed into escape baskets.

In a real emergency, the astronauts would ride the baskets down a 1,200-foot slidewire to a bunker on the western perimeter of the pad.

The drill came at the end of a practice countdown that served as a launch-day dress rehearsal for the crew and 150 to 200 engineers in the control center. It's the only time an astronaut crew suits up and boards a shuttle prior to launch day.

"This gives them an opportunity to work with the folks they are going to be working with on launch day, and for us, it's a chance to work with them directly in a pseudo-launch-type environment," Spaulding said.

The real three-day launch countdown is scheduled to begin Aug. 24.

Led by veteran astronaut Brent Jett, the Atlantis crew plans to carry out the first International Space Station assembly mission since the February 2003 Columbia accident. The main goal is to add a 17-ton section to the left side of the station's central truss.

Liftoff remains scheduled for 4:30 p.m. Aug. 27.

Published under license from FLORIDA TODAY. Copyright ? 2006 FLORIDA TODAY. No portion of this material may be reproduced in any way without the written consent of FLORIDA TODAY.

• Atlantis Shuttle Crew Ready for Mission, Launch Rehearsal
• VIDEO: Shuttle Commander Brent Jett
• VIDEO: Spacewalk in Infrared
• Complete Space Shuttle Mission Coverage
• NASA's STS-115: Shuttle Atlantis to Jump Start ISS Construction