Skip to comments.Actual text of that Nasa Email
Posted on 02/13/2003 7:59:02 AM PST by dark_lord
The text of an e-mail from NASA safety engineer Robert H. Daugherty to officials at Johnson Space Center two days before the Columbia disaster:
Excerpted stuff here...
The following are scenarios that might be possible ... and since there are so many of them, these are offered just to make sure that some things don't slip thru the cracks. ... I suspect many or all of these have been gone over by you guys already:
1. People talk about landing with two flat tires. ... I did too until this came up. If both tires blew up in the wheel well (not talking thermal fuse and venting but explosive decomp due to tire and/or wheel failure) the overpressure in the wheel well will be in the 40+ psi range. The resulting loads on the gear door (a quarter million lbs) would almost certainly blow the door off the hinges or at least send it out into the slip stream ... catastrophic. Even if you could survive the heating, would the gear now deploy? And/or also, could you even reach the runway with this kind of drag?
2. The explosive bungies ... what might be the possibility of these firing due to excessive heating? If they fired, would they send the gear door and/or the gear into the slipstream?
3. What might excessive heating do to all kinds of other hardware in the wheel well ... the hydraulic fluid, uplocks, etc? Are there vulnerable hardware items that might prevent deployment?
4. If the gear didn't deploy (and you would have to consider this before making the commitment to gear deploy on final) what would happen control-wise if the other gear is down and one is up? (I think Howard Law and his community will tell you you're finished)
5. Do you belly land? Without any other planning you will have already committed to KSC [Kennedy Space Center]. And what will happen during derotation in a gear up landing (trying to stay away from an asymmetric gear situation for example) since you will be hitting the aft and body flap and wings and pitching down extremely fast a la the old X-15 landings? My guess is you would have an extremely large vertical decel situation up in the nose for the crew. While directional control would be afforded in some part by the drag chute ... do you want to count on that to keep you out of the moat?
6. If a belly landing is unacceptable, ditching/bailout might be next on the list. Not a good day.
7. Assuming you can get to the runway with the gear deployed but with two flat tires, can the commander control the vehicle both in pitch and lateral directions? One concern is excessive drag (0.2 g's) during TD [touchdown] throughout the entire saddle region making the derotation uncontrollable due to saturated elevons ... resulting in nose gear failure? The addition of crosswinds would make lateral control a tough thing too. Simulating this, because it is so ridiculously easy to do (sims going on this very minute at AMES with load-persistence) seems like a real no-brainer.
Excerpted more stuff here...
Best Regards, Bob
(Excerpt) Read more at chicagotribune.com ...
I betcha there were 100,000 such emails on as many topics, covering every possible failure mode of the Shuttle.
And I love NASA's euphamisms for catastrophic failures: "We had a bad day" and "not a good day"...
I'd like to see that. You also might check CNN's website and see if they have the animation they showed this morning that was provided by some private company...
The animators took the various GPS coordinates where debris was found and made a visual depiction of how the breakup would look to an observer facing westward at approximately the alt. the Columbia was. It was pretty stunning stuff. Showed how pieces would fall off, then deccelerate from the drag, then fall earthward.
Really? Is there a link somewhere to this story?
The gear is lowered hydraulically after the gear-down command. If there is a failure in the hydraulics then the gear is blown down.
"For deployment of the landing gear, the uplock hook for each gear is activated by the flight crew initiating a gear-down command. The uplock hook is hydraulically unlocked by hydraulic system 1 pressure applied to release it from the roller on the strut to allow the gear, assisted by springs and hydraulic actuators, to rotate down and aft. Mechanical linkage released by each gear actuates the respective doors to the open position. The landing gear reach the full-down and extended position within 10 seconds and are locked in the down position by spring-loaded downlock bungees. If hydraulic system 1 pressure is not available to release the uplock hook, a pyrotechnic initiator at each landing gear uplock hook automatically releases the uplock hook on each gear one second after the flight crew has commanded gear down."
Just log in as ANNOYING, password ANNOYING. Works on the Trib website and many others, too.
Or, I guess, if the pyrotechnic initiator is prematurely set-off.....yikes.
Odd that doesn't show up in the coversation between NASA and the shuttle. Is there a delay/edit on that audio stream?
HOUSTON -- A sensor indicated space shuttle Columbia's left landing gear was down and locked 26 seconds before radio contact with the orbiter was lost, according to internal NASA documents obtained by the Orlando Sentinel.
If the sensor reading was accurate, it would have spelled disaster for Columbia, which broke apart above Texas on Feb. 1, killing seven astronauts. At least two other sensors indicated the orbiter's landing gear remained retracted.
Engineers are studying whether indications of an extended landing gear were real or the result of a sensor that sent bad data.
While NASA in the past week has released information about 17 sensors that showed abnormal readings during the shuttle's final moments, agency officials have said nothing about the landing gear sensor.
"There is nothing sinister about this at all," NASA spokesman Kyle Herring said. "They think this was a sensor reading and not an actual event."
Meanwhile, a NASA study looking at the temperature rise in Columbia's left wheel well has concluded that only an opening in the wheel well or wing cavity could account for the rising heat, a manager at Johnson Space Center in Houston said.
"The bottom line," the manager said, "is we had to have had plasma flow into the wheel well or wing cavity."
Information about the landing-gear sensor is one of several new details contained in a confidential Feb. 11 timeline of the accident drafted by NASA's Mishap Response Team at Johnson Space Center.
The timeline is similar to summaries released to the public last week that showed gauges on the shuttle's left side either shutting down or registering higher temperatures in the left wheel well and fuselage. But that summary stops just before a sensor began indicating that the left landing gear had dropped down.
Way funny! It works at the LA Slimes too! Thanks for posting this. I almost always refuse sign ups so now I can get in. I've tried the f.y. name and password before without luck. They must filter out that one.
I was under the impression that the moat was there to use instead of the runway for an emergency belly landing.
I agree. And here is my ADDITIONAL two cents on what I suspect happened:
As soon as I heard that the shuttle was TWO MINUTES EARLY over the DFW area, I thought to myself that NASA is NEVER off by that much time. They can go to the moon and come back RIGHT ON TIME!
Then, when I read the minute-by-minute NASA description of what happened and when, I learned that NASA was VERY, VERY DELAYED (literally at the last possible second) in giving the "go" for landing...and then, it was just a "oh, by the way, I guess I ought to tell you, you're go for landing."
That means that the Shuttle was traveling FASTER than they SHOULD have been for LONGER than they SHOULD have been, placing them FARTHER DOWN THE FLIGHT PATH than they SHOULD have been (which explains why it was TWO MINUTES EARLY over DFW).
That means that they had MUCH LESS TIME and DISTANCE TO SLOW DOWN and there would be HIGHER TEMPERATURE and FAR HIGHER STRESS ON THE WINGS due to the HIGHER SPEED going through the S-TURNS than normal.
Even if the bottom or wings were not compromised at all prior to coming back into the atmosphere, the EXTREMELY EXCESSIVE DELAY in giving the "go" for landing is probably what sealed their fate.
Remember, they had NO indication of an ACTUAL problem UNTIL AFTER they REENTERED the atmosphere. Prior to that, they were dealing with a "what if" scenario regarding the POSSIBILITY of damage to the tiles.
From everything we know right now, I believe it was the EXTREMELY EXCESSIVE DELAY in giving the "go" that ACTUALLY did them in.