Tough Turnaround Ahead for Space Shuttle Discovery
The STS-121 launch was scrubbed for a second day in a row due to concerns of thunder and lightning clouds.
Credit: NASA

CAPE CANAVERAL, Fla. - Launch pad workers have their work cut out for them in order to ready the space shuttle Discovery for a July 4th liftoff after Sunday's delay.

The process of standing down from today's scrubbed launch attempt, topping of Discovery's fuel cells and revving back up to a space shot on Tuesday - not to mention the constant threat of poor weather - is a challenging task, NASA officials said during a post-scrub briefing.

"The schedule is fairly tight," NASA launch director Michael Leinbach told reporters here at Kennedy Space Center. "Weather is concern for us."

Leinbach said the decision to scrub today's attempted launch of Discovery's STS-121 spaceflight - NASA second shuttle mission since the 2003 Columbia accident - early in the countdown due to unfavorable weather conditions will give pad crews more time to redress Discovery while handling the uncooperative weather.

Any severe lightning threats near Discovery's Pad 39B launch site could force shuttle crews to move to retreat to a safe distance until the storm has passed, NASA said.

Leinbach said that space shuttles themselves are well grounded when they sit atop their launch pads. A lightning mast and its associated wire lines protect the spacecraft from most stir

"We've never had a direct strike to the vehicle, ever," he added.

Pad workers are draining Discovery's external tank and will replenish the super-cold liquid hydrogen in the orbiter's fuel cells, and change out some payloads to prepare for a Tuesday launch.

NASA officials set the cost of the scrub turnaround at $1 million.

A safe call

Discovery's launch scrub was the second in two days for NASA's seven STS-121 astronauts, who were again awaiting liftoff inside their spacecraft when the call came through.

But the decision to postpone the shuttle's launch was a safe call for flight controllers.

"After a year of preparation, and after a very careful countdown, you don't want to do something that's not smart from a weather standpoint," said John Shannon, NASA's deputy shuttle program manager, during the briefing. "Nobody is going to remember that we scrubbed a day or two days a year from now. But if we go launch and get struck by lightning or have some other problem that will be very memorable."

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