NASA Press Conference Thread

[ksen]

NASA Press conference any minute now....

[snopercod]

NASA: "Vehicle lost at point of most-extreme heating - Mach 18."

"No commonality in the lost measurements (there goes my wire bundle theory or the DSC theory)."

"MOCR did not have TV showing the breakup that the press was showing." Sheesh...

[Sam Cree]

I think the guy said that offscale low means that the thing had just quit reading at all, maybe burned up?

[snopercod]

Yes, "offscale low" means it just quit reading. Shuttle measurements are normally scaled 1-5 volts (1 volt is the lower range limit). So if the signal drops to zero volts, you know the wires have been cut, the excitation has failed, or the sensor itself has gone open.

[snopercod]

Sorry. Too many threads today.

The tire pressure measurements are derived from strain gages on the rims of the tires. The signals pass through a dedicated signal conditioner [DSC] in the midbody, and a multiplexer/demultiplexer [MDM], then a pulse code modulation master unit [PCMMU].

There is no cockpit readout for these measurements. The folks on the ground watch them, and if they get way out of range, a message pops up on the shuttle CRTs (which it did in this case).

[Erasmus]

The most widely used type of strain gauge is also temperature sensitive. You need to have some means of compensating for that, in the form of a temperature sensor. Often this sensor is simply another strain guage of the same type, mounted in the same thermal environment, but without stresses being applied to it. This reference gauge is then 'nulled' with the gauge under stress to get (close to) a pure strain signal.

[steveegg]

I copied brake temp, but I was rushing. I could have been mistaken.

[_Jim]

At 7:56 was it a brake line temp sensor or a tire pressure sensor that showed an increase?

Let me get you a word-for-word account (I'll have to replay an MPEG file to get this accurately) ...

[steveegg]

I'll have to replay an MPEG file to get this accurately)

Could you link to it? Thanks.

[Starrgaizr]

Well, obvious question then is, could a rescue have been performed in time? Probably could not have made it to the ISS. Could another vehicle have made it to them before consumables were exhausted?

[michigander]

He stated that there was no capability to do a spacewalk examination for damage. They evidently had no way to go anywhere other than within the cargo bay.

[Tree of Liberty]

A Progress supply craft is due to go up tomorrow and dock with the ISS. I don't see why (in my layman's brain) it couldn't have been re-tasked to deliver items to the shuttle.

[Bronco_Buster_FweetHyagh]

"He stated that there was no capability to do a spacewalk examination for damage."


Actually, no. What he said was, they don't have the ability to space-walk outside the bay AND REPAIR TILES.

He qualified his answer, and directed his answer to something that was NOT asked.

I don't believe for a second that the shuttle mission and crew couldn't have done a space-walk JUST to look at their wing.

[mewzilla]

I'm glad I'm not the only person that guy is ticking off. Between their refusal to get pictures (there wasn't anything we could about it anyway), his refusal to think about debris coming off earlier, and some other things he's said, I've had it with this guy and his attitude problem.

[Jonah Hex]

Yep, that's the way I read it. Loss of temperature instrumentation data due to cable burn-through along with tire pressure increase due to temperature increase with subsequent LOS due to cable burn-through.

Although not a NASA engineer, it sounds like the left wing thermal protection system lost integrity with subsquent wing structure burn-through with disasterous results.

Not a good day...