NASA Calls Off Discovery Launch
A faulty fuel gauge on Discovery's external tank forced NASA to call off Wednesday's launch of the first shuttle flight since the Columbia disaster 2 1/2 years ago. NASA said the mission is off until at least Saturday.
The decision came with less than 2 1/2 hours to go before launch, as the seven astronauts were almost done boarding the spacecraft. Up until then, rain and thunder over the launch site appeared to be the only obstacle to an on-time liftoff.
The same baffling problem cropped up during a launch pad test back in April, and NASA has been struggling ever since to figure out the source of the trouble. But the topic came up repeatedly at meetings of top-level NASA managers this week, and the space agency said that it believed it had worked around the problem by replacing cables and other electronics aboard the shuttle.
NASA officials said it's not clear whether the problem is with the sensor itself or with the cables or the electronics boxes aboard Discovery.
It was also unclear whether the shuttle could be fixed at the launch pad or would have to be rolled back to the hangar, which would mean a much longer delay.
NASA deputy shuttle program manager Wayne Hale said that even in a best-case scenario, the shuttle will not be ready for launch before Saturday.
As recently as Monday, Hale described the sensor problem seen in April as simply an "unexplained anomaly."
The back-to-back failures suggest the possibility of a wider problem than one or two bad pieces of equipment.
NASA has until the end of July to launch Discovery, after which it will have to wait until September — a schedule dictated by both the position of the international space station and NASA's desire to hold a daylight liftoff in order to photograph the shuttle during its climb to orbit.
, which are responsible for making sure the spacecraft's main engines shut down at the proper point during the ascent. A launch could end in tragedy if faulty sensors caused the engines to cut out too early or too late."This is a critical system. They have four of these sensors, and they require all four to be operating at launch. Right now, it looks like they've got problems with two of those," said CBS News Space Consultant Bill Harwood. "It's a big disappointment."
The sensors let the computers know when the tank is dry and they can shut the engine down. If the engines were to continue running at high speed without fuel, it could lead to a catastrophe.
NASA said it appeared that the sensor was showing a low fuel level, even though the tank was full with 535,000 gallons of super-cold liquid hydrogen and oxygen.
The sensors "for some reason did not behave today and so we're going to have to scrub this launch attempt," launch director Mike Leinbach told his team. "So appreciate all we've been through together, but this one is not going to result in a launch attempt today."
During a fueling test of Discovery's original tank in April, one of its sensors gave intermittent readings. NASA could not figure out the exact reason for the failure but replaced the entire tank anyway to install a heater to prevent a dangerous ice buildup.
Shuttle managers considered conducting a fueling test at the launch pad on the replacement tank, but ruled it out to save time, saying that the actual fueling on launch day would be the ultimate test.
That mishap was an eerie reminder of the very thing that doomed Columbia — damage to the spaceship's fragile thermal shield.
"In any countdown, we have these problems but we don't have a horde of reporters reporting it," said Harwood.
"We are disappointed, but we'll fly again on another day," said David Wolf, an astronaut speaking from launch control.
"We have done everything that we know to do," NASA Administrator Michael Griffin said afterward. "Can there be something that we don't know about that can bite us? Yeah. This is a very tough business."
There is no overestimating the importance of this launch, reports CBS News Correspondent Peter King.
"Obviously, it is utterly crucial, for NASA, for the nation, for our space program, to fly a safe mission," said Griffin.
When asked if a successful return to flight would vindicate NASA, Griffin said that's not possible, that there is no recovery from that kind of a mistake.
"Through 100 years of aviation, the safety lessons that we who fly have learned and know are written in; other people's blood," Griffin said.
The families of the seven astronauts killed during Columbia's catastrophic re-entry praised the accident investigators, a NASA oversight group and the space agency itself for defining and reducing the dangers.
Like those who lost loved ones in the Apollo 1 spacecraft fire and the Challenger launch explosion, the Columbia families said they grieve deeply "but know the exploration of space must go on."
"We hope we have learned and will continue to learn from each of these accidents so that we will be as safe as we can be in this high-risk endeavor," they said in a statement. "Godspeed, Discovery."
"We'll take [the Columbia crew's] pictures and put it on the mid-deck so we can see it every day,"
. "Because we are doing what they would want us to do and we're carrying on their mission. All of us have learned from this. We're not going to forget it."A chunk of foam insulation the size of a carry-on suitcase fell off Columbia's fuel tank at liftoff and slammed into a reinforced carbon panel on the shuttle's wing, creating a hole that brought the spacecraft crashing down in pieces during its return to Earth on Feb. 1, 2003.