Castaway Resolution: Chapter 4

Sue and Numbers were on the case...

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Chapter 4.

Sue shoved her hair back and forced it back under the restraining clip. "Well, now I'm even more mystified than I was before." She drifted over to the coffee dispenser, filled the transparent carbonan cup again.

Numbers floated nearby, chaotic patterns flickering over his hide. "Yes."

"I'd expected to find a flaw somewhere—neglected maintenance, a mistuned coil, a one-in-a-million abrupt coil failure, something. The symptoms sure looked to me like some kind of beat between coils that turned out to have a positive feedback resonance. But. . ." Sue shook her head.

"Agreed. Instead, we have found nothing but exemplary records of service, coil condition monitoring records showing micro-tuning being regularly performed to maintain an overall synchronization less than one micro-Hertz, absolutely nothing to show a fault anywhere in either maintenance or design. No apparent manufacturing or component flaws, either."

"No. Those would almost all show themselves immediately in the synchronization data, if nowhere else." She looked across to the Bemmie's two visible eyes and grinned. "Good news for Captain Toriyama and his crew, anyway."

"Yes. There will still be a Board of Inquiry but this part will be mostly formality."

Her smile faded as she looked down. "But knowing what it isn't doesn't help so much. We need to have an answer for what it was, or at least whether it's something that could happen again."

"I have acquired data on all known lost ships," Numbers said. "I assumed that if anything like this had occurred before, we would already know about it. Therefore, if this phenomenon had been encountered by anyone else –"

"—the ship would have been completely destroyed. That fits with the recordings; Captain Toriyama was right in guessing that his ship would have been completely destroyed if they had been a second or two slower to respond. Good thinking."

Sue checked status first. In the last few days, the tow ships had arrived, docked and deployed their oversized Nebula Drives. Outward Initiative was finally underway to Orado; it would of course take a few months to actually reach Orado from this far out. Sue was tempted to go back to Orado Station using Raijin, but she really did have everything to do the investigation here.

She took a sip of coffee, resettled herself in the seat. "All right, let's see if we can get anything from that data."

Her omni displayed the data as a multi-dimensional plot of glittering stars, showing time and date of loss, type of ship, location of loss, ship size, and many other factors. The first thing that struck her was that there was too much data from the past. "I think we should filter to, um, nothing older than about fifty years."

"Why fifty years?"

"Because that was about the time that they deployed the current Trapdoor Coil design and basic operation guidance. Ships before then would have had some of the flaws the redesign was intended to eliminate."

Numbers buzzed pensively. "That will heavily reduce our numbers."

"I know, but it doesn't do any good to look at data that's on ships not built like this one."

"True. It's just that with delays on the order of a year between scattered systems, and months even on closer systems, propagation of records and data can take years. We'll be missing a lot of the most recent info."

"Let's try it anyway."

The plot darkened, then reappeared, this time with far fewer dots—but still quite a few. Across human-settled space, we're using a lot of FTL vessels.

There didn't seem to be a clear pattern here. "Do you see anything?"

"No, I. . ." Numbers' multibranched arms slowed, froze. "Wait. Let me try something."

The display darkened again, and then suddenly rematerialized. The scattering of dots representing lost ships had returned , but now they were mostly grouped into two separate populations, one low down and spread out along the x-axis which seemed to account for about seventy percent, one higher and focused far down the x-axis, though with still considerable spread, that comprised twenty-five percent of the total; the remaining five percent were scattered separate points.

Sue sat forward abruptly, knocking the sealed coffee cup away; she ignored it for now, as it was practically indestructible and not large enough to hurt anyone. "Well, that is interesting. What are our axes?"

"Estimated travel distance at loss for the x-axis, versus maintenance score history on the y-axis."

Sue stared. "That means that most losses in the last fifty years fall into two separate categories—one group is what you'd expect, ships that weren't maintained too well. But the other. . ."

". . . is ships with extremely high maintenance scores—usually new ships, or commercial vessels like this which try to keep all the drive systems in tip-top shape for efficiency and economy of operation! Yes, yes!" Numbers quivered and patterns like strobing squares and triangles circled across his body. "How fascinating! Not at all what I would have expected."

"I certainly wouldn't have." Sue's brain raced, trying to make sense of this. It was an assumption in essentially any engineering discipline: keep your machine in top condition, and it was less likely to suffer failure. But this graph seemed to say that you were actually safest if you kept it in 'pretty good' condition—not neglected and mistuned, but not perfectly tuned and polished either, and that made no sense.

Except, of course, it had to make sense. The division was too clear to ignore. "What's the p-value on this division?"

"Extremely low—about 0.00004."

"So essentially no chance that this just a random artifact in the data." She rubbed her chin. "Freaky, as a friend of mine might say. Why hasn't anyone else noticed this?"

"Well, I can't say that no one has, but it's only been relatively recently we've been accumulating enough data to make this pattern obvious. For all I know, of course, there could be a paper on it already published and on its way from Earth."

The coffee container gave a rippling chime as it struck the table; she caught it and put it back where it belonged. "You know what this means?"

"Probably not in the sense you intend. What?"

"There's some kind of flaw in the current design. A subtle one, but just the kind of thing that doesn't show itself for years until enough people are using it, or when you extend the design to some new regime. Can you sort this by size of ship?"

"Certainly."

The new plot showed what she suspected. "Looks like this disproportionately affects larger ships, don't you think?"

"Yes; p of less than 0.009. What sort of phenomenon are you talking about?"

"Well. . ." she searched her memory for a good example. "Oh, here's one engineering students have looked at for years—the Tacoma Narrows Bridge on Earth, back in the 20^th century. They built this really long, very narrow and shallow bridge high up over an area that had regular high winds. The design might have been fine somewhere else, under other conditions, but where it was it got exposed to winds of the right magnitude to induce really severe aeroelastic flutter that ended up tearing the bridge to pieces. After the fact they figured out what was going on, but no one really thought much about it beforehand, and it was really some minor design changes that led to the disaster."

"Oh. I think I remember that, but my instructors called it an example of runaway forced resonances."

"Argh," Sue said, rolling her eyes. "It's been mis-taught like that for centuries, I suppose it always will be. It looks like a resonance effect, I'll admit. But it's not, really. Resonance comes from a natural frequency of the structure, like my coffee container here," she bounced it on the table, causing a ringing chime before she caught it "being stimulated by some external force. If the stimulation's in-phase with the natural frequency or frequencies of the object, the resonance can build."

"But this isn't a resonance effect."

She shook her head. "No. The coils were all pretty much perfectly in tune. No sign of beats or resonances between them. The field was about as perfect as a crystal. . ." she trailed off as a sudden idea struck her.

"What is it, Sue?

She picked up the coffee container, stared at its shining crystal perfection. "Perfection. . . that might be it!"

The big Bemmie gave a momentary flicker of reddish annoyance. "Might be what?"

Lieutenant Sue Fisher sat forward eagerly. "Come on, Numbers—I've got some simulations for you!"