'City of Fresno'

[Nik_SpeakerToCats]

City of Fresno #152

Okay, the shuttle's Radar had found something with the direction, distance, relative speed and, yes, even the non-isotropic reflectivity, the 'twinkle', to fit my 'transit' model. Was it our target, though ? We agreed that 'Craterfield' lacked any discernible 'Anomaly' so, after notifying 'Fresno' of our logic and intentions, 'Speedbird' went in pursuit. Our wary journey took most of that day.

I suppose we'd become used to 'big' stuff: Iceteroids, moonlets and such. Creeping up on this elusive 'reflector' was weird. It wasn't until we were within about twenty kilometres that the shuttle's modest optics gave more than a few, slowly twinkling pixels. At a kilometre, we could make out a ragged, tripodal shape, slowly tumbling. Our approach gradually resolved that into what may have begun as a room corner, with three orthogonal frames or girders supporting two truncated panels. Now, it was about three metres on each edge

At our hundred metres stand-off, another detail became apparent: One of those short panels, book-ended by a sub-frame, was pierced by a snarl of service cabling and/or piping, both sides' exposed ends contorted like a basket of flash-frozen eels. I smiled. They would surely provide much useful data.

"Time to suit up," I stated. Secured for space, 'Big Mac' and I waited while the lock and hold were pumped down. After they opened, I rode the exo-suit's small Field Poles to within a dozen metres of our target. Although its rotational axis ran close to the 'apex', there was no convenient anchor point to grab, apply braking torque. And, although 'Big Mac' was armoured, I could not risk getting inside the tripod's swipe. So, I'd have to do this the hard way.

Like docking to a station's rotating port, I chose the least dangerous frame end. Tickling the 'Big Mac' Field Poles adjusted attitude and RPM until we matched. Now I could safely reach, clamp both suit gauntlets onto that frame. Slowly, very slowly, I let 'Big Mac' bleed off the rotation until we were 'halted' relative to 'Speedbird'.

I was glad it then took several minutes to deliver, coax our awkward catch into the waiting hold. I could tolerate having my wits whirled, but I didn't have to enjoy it. Certainly, this delay allowed my inner ears to fully recover. The hold closed, the first 180 milliBar of Nitrogen came in, the heaters began their slow work.

Now well lit, I could see how our catch had been assembled. Reinforced by doubler plates, main frames were through-bolted to shared corner brackets. Their bared ends showed where more had been torn away. Even these three surviving skeletal shapes stood some-what skew, wracked by disaster. Along each orthogonal frame, there were through-bolts and spreader plates, with a fair match to Jan's estimate of the hatch-way fringe's original spacing. Several bolts had retained a scrap of panel, most just hung loose. Parallel evolution: It some-what resembled the extruded aluminium alloy 'modular framing' I'd met at college.

The real prize, though, was that short panel's utilities' snarl. Each service duct was compression sealed into bulkhead fittings set through a multi-pierced doubler plate. On both sides of the divider, each and every pipe and cable carried an embossed metal label resembling the hatch-way's. Again, these had four lines of that Cuneiform font, perhaps the same language, certainly with visible differences in the sequences. As these short runs on both sides of the bulkhead were so clearly labelled, I'd hopes we could deduce much from them. The pipes, variously sized, all had flange ends. Two on the 'inside' of the 'tripod' and one 'outside' still mounted ring-clamped, quarter-turn isolator valves. A pair carried short labels, while the third had a torn stub. Two clearly co-axial, plus the three, four and 'many' cored cables clad in a range of insulation thicknesses and 'armour' sported splayed tails of silvery wire.

Slowly, as the hold temperature rose, more Nitrogen was bled in until we were back to near-ambient, air-suit compatible conditions. I spent the time doing an initial material survey with the 'Big Mac' sampling laser. The panels', doubler plates', nuts' and bolts' various magnesium alloys matched their counter-parts on the hatch-way. Further, the frames' and corner brackets' alloy matched those doubler plates'. To my surprise, all the wire, be it fine strands, coarse or chunky, was high-purity magnesium. Okay, the element had a conductivity about a third of copper's, some-what less than aluminium, but this was weird. Their polymer insulation was equally unsettling: My 'Big Mac' library, much more extensive than the sampler's mineral-rich default, found no match for this smörgåsbord of strange compounds. Nothing even came close. At least their elements were 'ordinary' rather than 'Trans-Uranic' exotica...

The pipe-work was stranger: Yet another magnesium alloy on the outside, each was lined by a sealing coat of magnesium oxide, perhaps anodised, then a layer of silica glass. This approach matched that of 'severe' chemical engineering, where glass alone was impracticable, where even the best hard-passivated stainless steel would not endure. But, and it was a seriously scary 'But', the combination seemed far, far too brittle for 'Rough Handling' applications. I doubted it would survive even mild flexure. And shocks ? Nah, these linings were sure to craze, fracture, shatter, expose bare metal: Be Not There !!

Already, I could be certain this magnesium-based hardware had no business in or even near our 'Human' 1000 milliBar, 40 % Humidity, 20 % Oxygen environment. And, yes, even our nominally 'inert' 80 % Nitrogen would support its combustion if ignited. Suddenly, I was glad our Gas Divers' side-catch included so much 'Noble' gas, all that Argon and Xenon. I'd expected such would be useful to 'purge' pipe-lines and tanks, 'shield' welding, but this undoubtedly 'Alien' tech would need it to survive...

[Belushi TD]

This delve into speculative chemistry is quite interesting. I'm looking forward to seeing where it goes.

Deducing info from the composition of the pipes and wires is also very interesting. I am certain there's a specific goal you've got in mind, but my knowledge of magnesium chemistry peters out at about 1944, when they decided that magnesium was not a great idea for the crank case of the B-29's engines.

Belushi TD

[Nik_SpeakerToCats]

Yes, magnesium is *weird*: Almost a 'split personality', okay to a certain point, then totally 'psycho'.

Plus, fighting magnesium fires is *interesting*, as will happily burn air, steam, CO2, nitrogen (!!) and a bunch of other stuff.

Either you quench it with a mega-douse of water, or choke with a genuinely inert gas...

[kdahm]

Personally, it'll be interesting to see what sort of atmosphere the booglies have that magnesium is all of available, not excessively hazardous to process or maintain, and is the best of the metals that are common there.

[Nik_SpeakerToCats]

City of Fresno #153

My first priority after un-suiting was to warn the rest of the crew. The bulk magnesium was probably 'fairly safe' in 100% Nitrogen. Most of this vacuum-exposed materiel should form a sufficiently stable oxide layer if briefly, very briefly, exposed to a whiff of our 'breathing' air from, say, a torn air-suit or wonky seal. Against that, those cable strands and filaments were divided enough to pose a serious auto-ignition risk. And then, per Murphy's Implacable Law and its many dire corollaries, they would surely, surely, light off the rest. Also, unable to identify their polymer insulation's curious chemistry beyond ominous elemental content, I had to call such 'Unknown Unknowns', so potential 'Murphy Bombs'.

'Speedbird' Comms got a laser-lock on 'Fresno', uploaded my suit-cam footage and preliminary scans, plus my urgent hazard assessment. This included my thoughts on possible necessity to 'blanket' with 'Noble' gas. The 'Fresno' duty crew acknowledged receipt, and confirmed they'd alert the Engineers.

An hour later, the Engineers' urgent missive to 'Cooberra', copied to us, warned that these 'Anomalies', so rich in Magnesium, were potentially 'Dangerously Pyrophoric', so the utmost storage and handling care must be employed. Also, as Magnesium could 'burn' in even a pure, normally inert Nitrogen atmosphere, could the Gas Diving please, please retain more additional side-catch Neon, Argon and/or Xenon ??

Yeah, verily, I'd called it right, at least for this stage: Certainly, better safe than incinerated...

As we'd spent much longer than hoped at 'Craterfield', then had to locate, chase its errant 'Anomaly', now secure in the 'Speedbird' hold, we were out of position for our next planned 'encounter'. In that lower orbit, its host moonlet was now significantly ahead of us. I reckoned it made more sense to tackle a similar one that would have been well behind, but had now almost caught up. When Lt. Svenson re-worked the 'MiniMax' factors, he agreed. As the shuttle's hold was now two-thirds full, he accepted it was probably the last for this sortie.

'Speedbird' needed three days to intercept this replacement target, much of which we spent in air-suits further documenting our tripodal find. The wealth of material data, which alloy was used where, was impressive. The services' paired labels provided a raft of correlations. Comparing them to the one on the 'Peanut' hatchway, we soon saw how one grouping seemed to identify that divider, and another which side. When Ben spotted a shallow arrow stamped on each pipe valve, with two facing left and the other right, we matched them to another group surely showing flow direction. Lacking the instruments capable of 'sniffing' trace residues, we could only log internal diameters and wall thicknesses. Those gave an indication of flow and pressure rating, while their lack of thermal insulation suggested they'd all been at 'local ambient'. I hoped there might also be some evidence trapped between valve stem seals.

Even cursory inspection suggested a clear hierarchy of power and voltage ratings for the cabling. Each 'chonky' core, suited to carrying 'much' current, had limits easily estimated from the cross-sectional area and Magnesium's nominal conductivity. Thicker insulation surely meant more voltage. A slim cable's thin wrapped or braided inner shield, and we'd one of each, suggested valuable signals passed via their single central core. Hopefully, the Engineers would be able to assess their inner insulation's dielectric properties, determine nominal impedance and optimal frequency regime for such 'Coaxial' runs. 'Twisted Pairs' populated both busy 'multi-cores'. This was more convergent evolution, as the Anwyc, Others and Sylvan Alliance had all found the same way to mitigate pesky cross-talk. Of course, as such pairs might be driven 'push-pull', they had a remarkably wide bandwidth from DC signals as low voltage or current-loop up to nimble data.

Beyond such factors, we noted panel, frames and sub-frame were peppered with hyper-velocity impact blemes. These ranged from finger-tip sized holes down to our limit of examination. Unlike the 'Peanut' find, this wreckage had clearly spent 'significant' time in 'open' space. How much damage was related to the original break-up ? We could only shrug. We had but minimal data for this orbit's micro-meteoroid flux. We lacked even the least data for 'nearby' inter-planetary regions. Such 'scatter-shot' damage could have accumulated slowly, or from even one pass through the dust stream from the least comet's tail. Also, this wreckage might be a 'lucky' fragment from a larger section, whose later collision flung scraps wild and wide, delivered this morsel into the gas-giant's sway...