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.
Here's the
drill
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.
Clock's
ticking
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.
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