8 THINGS TO KNOW ABOUT THE ENDEAVOUR LAUNCH
The president was on his way. Space shuttle Endeavour's astronauts were riding out to the launch pad. And a wounded Rep. Gabrielle Giffords had flown in from her Houston rehab hospital to watch her husband blast off Friday on the historic, next-to-last shuttle mission. Then it all came to a sudden stop. Here are 8 things to know about the Endeavour delay:
1 What's went wrong: The launch was scrubbed after engineers detected a failure in two of three heating units associated with an auxiliary power unit. The units are required to keep fuel lines from freezing in orbit. A short circuit -- either in a switch box controlling the heaters or one of the electrical lines in or out of the box -- has emerged as a primary suspect, but NASA engineers are not 100 percent certain. While these fuel lines are not particularly critical for launch, they are vital in ensuring that the airplane-like machinery of Endeavour work on re-entry -- such as landing gear and its rudder speed brake.
2 What happens now? The final lift-off for Endeavour won't happen any earlier than 2:33 p.m. EDT Monday, said shuttle launch director Mike Leinbach, and that's if the fixes are minor. Endeavour's external tank will have to be drained of fuel. It will take several days for engineers to reach the interior of the vessel to inspect the faulty circuit box, he said. When mechanics reach the box, they could determine that even more than 72 hours are needed to fix the problem. A more complicated repair would push the launch to May 9.
3 Why this mission matters: The Endeavour crew is to install a $2 billion particle-physics experiment, the Alpha Magnetic Spectrometer, at the space station, where it will search for evidence of the elusive "dark matter" that is thought to be ubiquitous in the universe. The shuttle will also deliver spare parts to the station and will leave behind its long boom that is used to inspect the spacecraft for damage after launching. The Endeavour is the youngest vehicle in the shuttle fleet. With 25 missions under its belt, it has flown 116 million miles.
4 When the crew found out: Commander Mark Kelly and the rest of the six-man crew had gone through final medical checks and donned their bright orange flight suits and were riding in a van to the launch pad when the postponement was announced. Normally the astronaut van passes the launching control center on its way to the pad; this time, the van made a U-turn and parked in front of the control center.
5 Will Rep. Gabrielle Giffords stay? Giffords, who is recovering from a gunshot wound to the head from an assassination attempt in January, had flown in Wednesday to watch her husband, Kelly, blast off. "Bummed about the scrub!! But important to make sure everything on shuttle is working properly," her staff tweeted. A post on Giffords' Facebook page said her "travel plans at this time are undetermined." However, a close friend of the Arizona congresswoman said Giffords' family indicated she would stay in Florida at least until Monday. She had planned to watch from a private area.
6 President Obama's visit: Obama and his family arrived shortly after the mission was scrubbed and decided to go on with the Kennedy Space Center tour that had been arranged for them. The president talked with Giffords for about 10 minutes before he met with the crew. Before going in to see her, the president greeted Kelly in a corridor. "I bet you were hoping to see a rocket launch today," Kelly said. Replied Obama, "We were hoping to see you." They shook hands and embraced before Kelly updated Obama on Giffords' condition.
7 Crowds had gathered: Officials had predicted up to 750,000 onlookers for the launch. Some drove 19 hours straight through tornado-ravaged land and some flew thousands of miles to see the launch. Tim Guiteras, 11, and his father, Tom, flew in from Los Angeles on the Thursday night red-eye. They went to their hotel at 5 a.m. to take a short nap, and then drove to Titusville, a town across the water from the launch pad. But when they arrived, they saw people headed to their cars. Tom Guiteras checked his iPad to find out the bad news. "I'm really disappointed," said his son, who wants to be an astronaut. It was the second time the two had bought plane tickets to see Endeavour launch.
8 What's next for the shuttle program? Shuttle Atlantis, which is due to fly in late June as the 135th and final mission of the shuttle program.
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