Saturday, June 24, 2023

Reporting on Titan

If he was reported correctly, Cameron implied that a hydrophone picked up the bang at the (presumably sound delayed) time that communications with Titan stopped. It was possible to come up with scenarios in which the crew survived, but not if there was a bang when communications went dead. We've all read that the Navy picked it up (and didn't understand it at first), but was there a hydrophone on the Titan's sevice ship? Another report claimed that they'd jettisoned the ballast and were on the way back up. I assume telemetry would include such things if they really happened.

Would the staff fail to mention such things before the search starts? Maybe. Embarassment, reluctance to squelch all hope...

One news source, which I will charitably leave nameless, claimed that the rapid compression in an atmosphere "with lots of hydrocarbons" ignited and reduced the humans to ash. (*) Yes, rapid compression superheats gas; no there wasn't lots of hydrocarbon in the air; and in any case the thermal mass of the gas would be small. The mechanical destruction of their bodies killed them, not a flash fire. Although--I don't have a good intuition for what you get when you super-compress a liquid. I assume it heats up too--compressed by about 2%--but that doesn't seem like a huge effect. (I'm having the dickens of a time trying to get the equation of state for liquid water, and I'm getting sleepy.) I'd guess the heating due to the shock wave traveling through the body to be greater.

Just after the accident several stories disparaged the use of a game-controller brand of joystick--as though a machine designed to work reliably despite abuse by excitable gamers is somehow inferior.

And "I warned you" types are coming out of the woodwork. Me? It wasn't on my radar and I had never looked at the design--and would have had to do quite a bit of research to say anything intelligent about the use of carbon fiber hulls. I'm pretty sure I'd have suggested testing to failure several times before trusting people in it, but I've never been in that kind of position, and I might have gotten complacent too.

Specific details can be keys to determined what happened, but in between cya and mistranslation and reporter ignorance, you can't trust the details. Or, sometimes, the big picture.

FWIW about ratings: we used to use some high voltage cables that were rated for 1000V, with SHV connectors rated for 5000 (now. I think they were also for 1000V back in the day). We ran them at 6000V.

(*) I will uncharitably point out that Newsweek's fact checker got the fact-checking wrong. No, the vessel did not become superhot, but the air did.

UPDATE: To be clear, the 2% compression is just for the liquid parts of the body. Lungs and other less dense things get mashed flat.

UPDATE*2: Also note that where and while bulk motion in a gas is comparable to the average speed of molecules in it (O(500 m/sec)), temperature isn't well-defined. When the gas motion is randomized again, you can define temperature again. And yes, I did find some formulae for the equation of state for water, but when I varied the temperature I found that they went weird at higher temps (O(300 degrees)), and I concluded that they might not apply in a wide enough domain for me to assert that rapidly compressed body tissue wouldn't get hot. So I don't know for sure.

1 comment:

Korora said...

May God receive them and comfort the families.