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| -Short Attention Span Theater- |
| NASA Finds Flaw Could Have Doomed Another Shuttle |
| 2004-03-23 |
| NASA has discovered a potentially disastrous mistake made more than 20 years ago on the space shuttle Discovery and plans to replace key parts on all three of its shuttles, the space agency said on Monday. Gears were installed backward on the speed brakes in Discovery's tail section and could have failed under the stress of an emergency landing, said William Parsons, the shuttle program manager. "The bottom line was, it was not good," said Parsons, who told reporters the Discovery had flown safely 30 times since 1984 without the gears causing a problem. The most likely scenario for a disaster would have come if the shuttle had needed to make an emergency landing at the Kennedy Space Center in Florida after an aborted launch, when the aerodynamic stress on the gears would have been greatest. The reversed gears were found in an actuator that works the speed brakes, which are essentially flaps that flare out from the tail section to create aerodynamic drag and slow the shuttle. Small cracks and some corrosion were also found, surprising NASA engineers. After the original actuators were replaced, NASA also tested extra replacement parts built 17 years ago, and found that one of the spare actuators also had the gears reversed. Discovery is NASA's oldest remaining shuttle after the loss of the Challenger in 1986 and the Columbia in 2003. It has been chosen as the first craft to resume flying once the post-Columbia suspension of shuttle missions ends. That Discovery mission is scheduled for March 2005, and Parsons said the added work would not necessarily cause a delay. Parsons said the fault had been traced to the installation by a contractor, Hamilton Sunstrand of Rockford, Illinois, which had reviewed its procedures and found there was nothing to prevent the gears being installed backward. "Yes, I'm surprised. It's a process escape that shouldn't have happened," said Parsons, who became the shuttle chief after the Columbia disaster and has overseen the $250 million return-to-flight effort. The company's program manager for the parts, Rudy Valdez, said the actuators are configured in mirror-image pairs, but the gears themselves are identical and were inserted one of two ways depending on which side of the pair was being built. Hamilton Sunstrand has changed the fixtures used to assemble the actuators so that now each gear can only be inserted one way, Valdez said. |
| Posted by:Steve White |
| #6 Prestigious a program as it is, it's still a government contract. Lowest bid wins. |
| Posted by: tu3031 2004-3-23 11:12:07 PM |
| #5 For what it's worth, everytime I see the SRB ignite I pray, and listen, and scream, and then pray a little more. Amd then, just then, I womder about DynaSoar. |
| Posted by: Shipman 2004-3-23 7:10:52 PM |
| #4 ...My dad went to work at NASA Lewis not long after the Challenger accident, and he told me then that the engineers who put the system together had no idea that so much of what they did meant certain death for the crews - basically, each team was given their work, told notr to worry about any potential problems, and that other teams would handle the emergency checklists. It became obvious after Challenger, and even more so after Columbia, that NASA really was playing Russian Roulette with the system. And for what it's worth, a lot of the NASA engineers also believe that the shuttle fleet will not survive until 2010 when Constellation comes on line. The opinion seems to be that the law of averages will catch up with the three surviving shuttles long before that. Mike |
| Posted by: Mike Kozlowski 2004-3-23 10:26:01 AM |
| #3 Ship: Most of the fuel is gone, used to reverse the Shuttle's direction and send it back towards the Cape, by the time it's released. The release itself is the trickiest bit of the abort -- attempting to make the tank move away from the orbiter, they essentially do a short "power dive", shut down the engines, release the tank, and thrust away from it using the reaction control systems. You have three possible results from this: (1) it works, and the rest of the flight is like a normal entry; (2) you hit the tank anyway, and the orbiter breaks up; or (3) you get away from the tank, but the "power dive" maneuver itself is stressful enough that the orbiter breaks up. There's a very good discussion of the RTLS abort available at this link, if you're interested. |
| Posted by: snellenr 2004-3-23 9:57:33 AM |
| #2 So much of the program ended with the words "You're so screwed!" that they had to put in the abort scenarios. Everyone feels good, and that's about it. |
| Posted by: Chuck Simmins 2004-3-23 9:31:30 AM |
| #1 Hell, returning to KSC after a main engine abort was pretty much a toss-of the coin anyway. I've always wondered what what supposed to happen to the fuel tank (still half full) once the guiotine came down on the fuel lines.... |
| Posted by: Shipman 2004-3-23 8:20:28 AM |