New problem found on Discovery
Crack found in fuel tank foam - could further delay launch
By Alan Boyle
Science editor
MSNBC
Updated: 17 minutes ago
CAPE CANAVERAL, Fla. - NASA managers were deciding Monday whether to call off a scheduled Fourth of July space shuttle launch after a 5-inch-long crack was found in the foam of discovery’s external fuel tank.
The crack was spotted during an overnight inspection. NASA had scrubbed launch plans Saturday and Sunday because of the weather and had removed the fuel from the tank.
The inspectors found a crack 8 inches deep in the foam on a bracket near the top of the external fuel tank.
On Sunday — for the second day in a row, poor weather forced a postponement of the shuttle Discovery's launch. Another attempt had been planned for July 4th.
"We've decided to terminate the count today, stand down for 48 hours" and get the shuttle ready for a Tuesday launch attempt, launch director Mike Leinbach told Discovery's astronauts as they waited in their seats on the launch pad.
"Looking out the window, it doesn't look good today, and we think that's a great plan," shuttle commander Steve Lindsey answered.
The delay will give the launch team a chance to replenish supplies aboard the shuttle — and also give the crew a chance to rest up.
The next opportunity to launch Discovery to the international space station is scheduled for at 2:38 p.m. ET Tuesday. If the shuttle goes up then, it would be the first manned U.S. spaceflight to be launched on Independence Day.
"What a great gift NASA could give to the nation to return the shuttle to operation on Independence Day," said John Shannon, chairman of Discovery's mission management team. "We're really looking forward to that, and if the weather is good, that's exactly what we'll do."
The factors behind Sunday's postponement were the same as the factors behind Saturday's scrub, only more so. From the very start, forecasters said there was only a 30 percent chance of acceptable weather at launch — and conditions were consistently "no-go" as the countdown ticked on. Rain showers, thick cumulus clouds and high anvil clouds capable of producing lightning swept through Kennedy Space Center's surroundings.
Leinbach said his team saw a chance that the skies might clear in time for liftoff Sunday. But instead, the weather took a turn for the worse.
"It became very obvious ... that the weather was just not going to cooperate with us today," Shannon said.
Once it became clear a launch was not in the cards, Leinbach urged that the countdown should be stopped early, to maximize the time available to replenish the shuttle's liquid hydrogen fuel. That, in turn, would maximize the chances to extend Discovery's mission to 13 days.
The weather outlook improves to a 60 percent chance of favorable conditions for launch on Tuesday, said Air Force Lt. Kaleb Nordgren of the 45th Space Wing's Weather Squadron. That figure dips to 40 percent on Wednesday.
In response to a question, Leinbach said each scrub on a weekend or on a holiday like the Fourth of July costs NASA in the neighborhood of $1 million, for supplies as well as overtime costs.
Lightning threat
Both on Saturday and Sunday, the proximity of lightning-prone clouds was the prime concern. If Discovery were to fly through the wrong kind of clouds, it could spark a lightning strike, as occurred during Apollo 12's launch in 1969. Although no lasting damage was done that time, NASA wants to avoid a repeat.
The launch team has to cope not only with afternoon storm clouds but also with a relatively short five-minute opportunity for liftoff on a given day. (It's actually 10 minutes, but NASA generally targets just the last five.)
The reason for the short time frame is that NASA wants to launch Discovery during daylight, so that debris from the shuttle's external fuel tank can be clearly seen. In addition to the daylight factor, NASA has to time the launch so that Discovery is in the right orbital position to catch up with the space station two days after launch, as scheduled. After five or 10 minutes, the timing is off.
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