Breaking News: NASA Scrubs Atlantis Launch Again

"Liquid hydrogen sensor number three has failed," reported  NASA Launch Commentator George Diller shortly after fueling began.  The sensor malfunction was almost identical to the failure that scrubbed Atlantis' intiial launch attempt on Thursday. "This is not good news," said Diller., 

After two days of delays, NASA managers and engineers decided to proceed with today's launch attempt but with scritcter flight rules that required all four fuel gauges to be working properly. "In a way this could be a good thing," said Diller because NASA engineers are closley monitoring the problem to try and get a better understanding of what's causing the sensor failures. "This may very well help us get to the bottom of this problem."

Atlantis had until Thursday to make its launch window but with this latest delay made it unlikely the shuttle would meet the Dec.13 deadline.  NASA said the earliest Atlantis could launch is Jan. 2 or Jan. 3. Atlantis and its seven-man crew first intended to launch Thursday but the attempt was scrapped when two of four gauges showed faulty readings during the fueling process. The sensors are part of a backup system that would kick in if the tank began to leak during the shuttle’s ascent into orbit. The sensors would safely shut down the engines and prevent an explosion.

NASA managers planned to meet later Sunday to determine how to proceed.

After a daylong review session on Saturday, NASA decided to move forward with Sunday's launch.. Senior shuttle managers signed off on a plan to tighten flight rules and shorten the five-minute launch window to one-minute to minimize the chances of the tank running dry too soon. Engineers said the extra precautions will keep Atlantis and its seven-man crew as safe as possible during launch. Under the new rules, NASA will proceed with the countdown only if all four of the gauges in Atlantis' external hydrogen tank are working properly.

"We'll fill up the tank and we'll see what we get," said NASA’s Atlantis Mission Management Team Chairman LeRoy Cain. "If we meet our criteria, we'll go fly and if we don't, we'll scrub and we'll get a good tanking test and we'll go forward from there." Cain said Atlantis astronauts had a major role in developing the tightened flight rules plan and described shuttle commander Steve Frick as “deeply involved” in all of the decisions. 

But the teams laid out a solid plan of action in the event of another failure like the one that occurred ths morning. “If we have any other anomalies, or a repeat of an anomaly, then we think it is worthwhile to stand down and troubleshoot. The nature of that troubleshooting and how long it would take is a little bit open ended. We'll wait to see what happens before we decide that."

Atlantis and its seven crew members had been scheduled deliver and attach the European Space Agency’s Columbus research laboratory to the International Space Station during the planned 11-day mission. Pilot Alan Poindexter will be at the controls with veteran astronaut Frick in command. The remaining STS-122 crew members include Flight Engineer Rex Walheim, Leland Melvin, Stan Love and European astronauts Hans Schlegel of Germany and Leopold Eyharts of France. Eyharts was to replace Lombard-native Dan Tani who had been scheduled to return to Earth in Eyharts' place aboard Atlantis. 

Tani has aleady spent nearly two months in orbit aboard the space station and now has to face the possibility of even more time aboard ISS until Atlantis can get off the ground and go get him. 

"I'll go home with the Atlantis crew -- they are my ride home so if they launch this week then I will be home by Christmas,” said Tani. “That would be a big advantage for my family and myself. Let's hope Discovery launches on time," he said in an interview before today's decelopments.  Now it appears Tani will spend Christmas with his Expedition crew mates high above the Earth.

The Atlantis STS-122 mission was to be the fourth NASA shuttle flight of 2007 and the second since October to dedicated to construction of ISS.

On the web: NASA