Air Burst

7 04 2012

A high-pressure system had formed far to the north of the Colonies. Air warmed at the equator, upon which the Colonies straddled, had risen and drifted away toward the poles; short of twenty degrees north latitude, this mass of air descended to the surface and created a cool, slowly-moving ridge. That ridge pushed down toward the equator, weakening as it moved.

It was thus a clear, cold day as Mierhof and I stepped from the crawler and out onto Fram’s surface.

We were four hours’ north of the Colonies, just over two hundred kilometres from the Yom Kippur mining site. Here there was a clear plain, hundreds of kilometres wide, between two ranges of mountains formed by the uplifted ejecta of massive, ancient craters. The regolith was shallow and, with the bedrock, we made good speed on this relatively flat terrain.

There was a light wind stirring the regolith, and, due to Coriolis force, it came from the northeast. Mierhof swore.

“God damn it’s cold,” he said, tensing up against the wind and holding his body heat jealously. “Reminds me of winter back Home.”

The average atmospheric temperature had dropped as we moved away from perihelion. I tapped at my tablet with the stylus.

“Nine degrees,” I replied.

We both wore knit caps to cover our heads, the most exposed parts of our bodies. Mierhof wrapped a thick scarf around his neck; I enjoyed the bracing cold on my skin. I took a deep breath and pulled away my facemask. I exhaled slowly, watching the steam roll away from my mouth. My breath looked strange, stunted, suppressed as it was by the thick atmosphere. I smiled, and quickly replaced my mask.

“It’s not a Goldilocks world,” I said to Mierhof, “but we could have done a lot worse.”

To the west, the plain rose in a long but gentle incline, and the horizon was far above us. The parallel tracks of our crawler diminished into a point at the crest of that incline. The constancy of that incline belied the violence of its formation: we stood in the basin of a astoundingly large impact crater, so large and so old that it was almost unrecognisable to human eyes. This basin was almost a thousand kilometres across, a depression in Fram’s surface that had been weathered by three billion years of anabatic winds and pockmarked by thousands of younger craters. The force of the impact had punched the surrounding crust upwards, forming extensive highlands that planed away to the far hemisphere.

Mierhof and I unpacked the ground-penetrating radar system from the flatbed of the crawler. Mierhof was remarking at how long it had been since we had used the survey system. We cleared an area of regolith with snow shovels, creating a flat space to deploy the rig.

“You get on that side and get that plate locked down,” he said.

With a thumpthumpthump I hadn’t missed at all, we drilled a borehole and then inserted the GPR antenna into the shaft. I attached my tablet to the rig and brought up the radargram. The terrain at the edge of the basin was heterogeneous, composed of brecciated, smashed bedrock suspended in regolith. With the GPR we might penetrate fifty meters below the surface, far less than had we been working on basalt bedrock.

With Mierhof and I holding each side of the rig for stability, the A44 began to thump out subterranean radar pulses of ultra-high frequency microwave and radio energy. Immediately, reflections reached the rig’s sensors, creating a blurry radargram on my tablet that was clarified with each pulse.

“God damn,” Mierhof said. “They might have been right.”

“Fram!” I replied. “Let me see!”

There were a series of colours, moving like infrared from the warm surface down through yellows and greens to a deep blue. But those colours between red and blue were arranged in parallel bars, and from those bars I could see what was buried beneath me as though staring up at a cross-section of the strata.

There were half a dozen elliptical shapes, like the bow wakes of ships moving up the screen, that showed the presence of large bolides of basalt, and these shapes were suspended on strata lines at various depths. But most interesting was the bottom half of the image. The various stratigraphic layers of regolith and spalled bedrock, written in yellow and green, trailed away into featureless blue; beneath this area of ultrafine regolith there was a second section, an area of high reflectivity, a strata of green highlighted yellow and arrayed in a smooth, flat strata.

“Huh,” I managed.

“Clathrates,” Mierhof replied.

“Looks like it.”

Forty meters beneath my feet, it seemed, in the basin of this impact crater, was a layer of methane ice, a clathrate compound of methane trapped within a lattice of ice. This was a deep sedimentary structure, buried beneath a billion years of regolith. And this layer was thick: from this preliminary GPR pulse, possibly tens of meters thick.

We had found methane ices pooled in the basins of craters near the Colonies, but these had been thin sheets, preserved by the regolith that covered them, ices so thin that once exposed to the thick and warm atmosphere of Fram, sublimated away like magical vespers. But calculations had suggested that, assuming similar ices to be found in craters across Fram, the total amount of water ice was much higher than we had ever expected from the hydrogen and oxygen in the atmosphere.

The theory went that methane produced by the methanogens was trapped within water ices deposited by cometary impacts, and that, in the deep winter of aphelion, water and methane snowed from the skies. This snow was buried by the movement of regolith and, preserved in the depths of craters by the cold of that surface regolith, large reservoirs of methane clathrates might form in the oldest and deepest basins.

Aquifers of vital water and methane might exist across Fram’s surface, undetected and in unimaginable quantities. And so we looked to the largest and most ancient craters for proof.

“Imagine it,” Mierhof said. “All that water, there all the time, waiting to be mined.”

I smiled.

“Think of the energy! We could burn the ice for power and heat. Natural gas. God. Water – and a warmer world.”

That was when it happened.

I had just told Mierhof to get the equipment for a core sample when, from the corner of my eye, I saw a streak of blue-white light, arcing downwards toward the horizon in the north-east. As I turned, I saw that streak begin to fragment into pieces, and as I stared at that cone of smaller arcs of light, I immediately knew what I was looking at.

“Christ, get down!”

I jumped at Mierhof, and with both hands on his shoulders I pulled him to the ground. There was a flash of light. I closed my eyes and buried my face in the regolith, but still I could see the light, and the back of my neck grew hot.

After a moment, Mierhof stirred.

“’The Fram was that?”

We both got to our knees. I wiped away dust from my faceplate. Suspended on the horizon was a dirty column of brown and black, a thick stem of fire and dust balanced on an expanding cloud at its base. Separated from that firestorm were a series of geysers, high plumes of regolith shot up into the sky by dispersed impacts.

“Air burst,” I said at length.

“God damn,” Mierhof replied, rubbing one hand through his beard. “Look at all those impacts. Broke up in the air and shot all those fragments down like a shotgun.”

“What do you think, five or six kilotons?”

Mierhof laughed. “More like ten! My God, look at it.”

The base cloud continued to expand, driven by a pressure shock in the atmosphere. It engulfed the geysers of suspended material that surrounded the airburst cloud. That airburst cloud rose upwards as the heated column of air rose, drawing in cooler air around it; the rolling updraft slowly formed a sinister mushroom cloud. But the wind from the high-pressure front pushed the cloud south-east, and it began to disperse even as it was still rising, raining regolith and vapourised comet across the basin.

Then the sound wave rolled over us, a massive clap that trailed away into a low roar punctuated by the a series of crisp bangs that might have been the impact of the fractured pieces. With that roar came a ground tremor to announce the violent creation of Fram’s youngest crater.

“Here’s a scary thought,” I ventured. “That comet must have travelled billions and billions of kilometres. Imagine if it had fallen just twenty kilometres short.”

Mierhof looked at me with eyes that held little patience for cynicism.

“Here’s a nicer thought: imagine that much force hitting a clathrate deposit. All that methane and water vapour quickly dumped into the atmosphere. We might warm Fram in decades, not centuries…”

We watched the cloud disperse for half an hour before we began to drill the bore for the core sample.

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Criticality

29 11 2010

“We’ve had some serious problems with the purity of the graphite,” Faraday said.

Clarendon exchanged a quick glance with the other members of the Presidium. “How serious?”

“Well,” Faraday replied, “at first we were measuring cross sections of between fifty and five hundred by ten to the negative twenty-seven square centimetres. Unacceptably high. Using graphite of such unrefined quality would only lead to a runaway reaction and a meltdown.”

“And now?”

“After some to-and-fro with our colleagues over at Alpha-4, we’ve managed to get the average cross section down to four point oh to four point seven by ten to the negative twenty seven square centimetres.”

Faraday took a stylus to his tablet and wrote: 4.0 – 4.7 x 10-27 cm2.

“For a uranium and graphite reactor to operate at all, we need a cross section for slow neutron absorption of no more than this.” Beneath his scrawl, Faraday scribbled another figure: 4 – 5 x 10-27 cm2. “It turned out after some testing that our first batches were contaminated with traces of boron and other rare elements.”

“So it – the graphite – it is safe to use?”

Faraday smiled. “We would not be here today if it were not.”

Faraday went on to explain to the delegation that, in the six months since the First Congress, the two mining sites had assembled a stockpile of six tons of uranium and almost four hundred tons of graphite. Not all of this graphite had been mined in that half-year; much had been mined before the Congress, and, after refinement, was put to use as the moderator in the nuclear reactor.

Through the transparent blast shield, the group looked down on a channel dug into the regolith and bedrock. The channel sloped downwards through a shallow gradient over fifty meters, at the end of which was the reactor. The reactor was dug into a pit a further ten meters into the ground. The regolith and fractured bedrock were the primary shielding for the reactor. Between the control room and the reactor were blocks of basalt lined with concrete and paraffin, and lead walls filled with boric acid.

The pile itself was a cubic lattice of uranium metal rods suspended within a sphere of graphite. This sphere was embedded within polished slabs of basalt, so that the entire reactor appeared as a black-grey monolith set into the red-brown crater wall. Steel cables ran from the top of this sphere along suspended pulleys back to the control room. These cables were attached to the control rods: six bars of cadmium that hung above the centre of the pit.

“The cadmium rods control the reaction.” Faraday explained, as he gestured to the point where the cables disappeared into the pit. “They can be lowered or raised into the reactor. Cadmium is a strong absorber of neutrons; dropping these rods into the reactor prevents a chain reaction from developing.”

Clarendon asked, “And, presumably, these rods can be dropped down in an emergency to prevent a runaway reaction?”

“Indeed. We call that a ‘scram.’ ”

The reactor had been constructed in assemblies. Graphite was laid in layers and into this mass of graphite were drilled the holes for uranium slugs. There was room between each of the uranium slugs for neutrons from one slug to bounce off carbon atoms in the graphite before entering another slug. This action slowed the neutrons and allowed them to better resist absorption by U238 nuclei and instead be absorbed by U235.

“This is a rather modest design,” Faraday said. “Necessarily so because of our limited resources.”

Clarendon stepped forward and brushed his fingertips along the control panel. “Mmm. Once we have amassed more experience from this reactor, we may build others. Larger, more efficient. But the colony does not yet have an urgent need for trans-uranic elements.”

Faraday brought up a display on the blast shield, and tapped away at it with his stylus. Graphs slipped from the heads-up display into the margins until the central display was flanked by a half-dozen graphs and tables. Through these coloured images, Clarendon and Faraday watched a group of figures retreat from the generator several hundred meters away.

Faraday turned to Clarendon and the other delegates. “Shall we?”

The Presidium members nodded, and Faraday worked the controls and began to withdraw the cadmium control rods from the reactor. Immediately, the neutron counter began to click away, and a line graph on the right spiked. Faraday pointed out a number of graphs – gamma-ray and neutron counters, reactor power levels, galvanometers – and commented on their significance. Faraday pointed at one graph in particular.

“That’s a boron trifluoride counter, buried under the reactor. It’s showing neutrons have penetrated the basalt shield around the pile.”

Faraday withdrew more of the control rods, but kept two of the emergency rods within the pile. Neutron levels multiplied. There was linear growth of reactor power, a steady but shallow rise on a line graph updated in real-time. The clicking noise grew rapid. One of Faraday’s colleagues was calling out data from counters in decimals of one.

“Point seven five. Point eight. Point eight five. Here it comes.”

When the neutron intensity reached one, Faraday locked both the control and emergency rods in place. He turned to the information that his colleague was examining. After a few moments of altering the filters and examining the data, he turned to the Presidium members.

“We have achieved criticality.” Faraday smiled. “We have a self-sustaining chain reaction.”

“Mmm,” Clarendon replied. “That’s it?”

“That’s it. There are no bright lights or loud noises to announce criticality, but with nuclear reactors, it is generally better that way.”

Clarendon did not return Faraday’s grin. “And to introduce lithium to the reaction? To breed tritium?”

Faraday explained that the design of the reactor included a channel, like one of the holes drilled for the uranium slugs, into which materials could be remotely introduced.

“We’ll need to boost the power of this reactor before we do that, however,” he continued. “Reactors produce one gram of plutonium per day at a thermal power level of 500-1500 kilowatts. This pile could be powered up to around three thousand kilowatts, but not for any substantial period of time.”

“And it is now running at…?”

“About 500 watts.”

“Ah.”

“As more uranium is refined at the diffusion plant, we’ll add more assemblies to the pile and slowly boost its power. Nonetheless, we should appreciate the first nuclear reaction generated using materials not of Sol.”

Now Clarendon smiled. “With the exception of the stars themselves, Dr. Faraday.”





U₃O₈

8 02 2010

The miners at the COIL rig in Yom Kippur doubted very much that any significant concentrations of uranium would be found in the base of that crater; they said as much at the conference, when the question was posed to them.

“Sure, the bases of craters are where a lot of metals and minerals are concentrated,” they explained. “Pressure, temperature, fractured bedrock, fused basalt – but the impactor itself is mostly vapourised, and the pressures of impact can’t concentrate what isn’t really there to begin with.”

Yom Kippur, like Hashoah and Yerushalayim and the other nearby craters, were hundreds of millions of years old; the pair of craters laid over each other in which the four colonies were nestled were older yet. Beneath the surfaces of each crater were hundreds of meters of eolianite, regolith deposited by the wind and built up over those millions of years. In this layer the regolith had been compressed by the weight of subsequent layers, and now formed a soft sandstone, tinged purple by high levels of manganese. This layer of desiccated eolian sandstone was laid over bedrock fractured by the force of the impact which had created the crater. It was through this deep fracturing that volatiles and liquefied metals had seeped upwards from the ancient asthenosphere.

“The bigger craters have sheets of basalt overlaid the brecciated bedrock. The tremendous forces and temperatures of the impact that made those enormous craters fused the regolith and eolianite into great sheets of melted, crustal silica – evidence that these impactors created their own magma lakes…”

None of the minerals brought up by the COIL rig had shown substantial concentrations of uranium, which lent strength to the theory that pitchblende veins simply didn’t exist in Fram’s unearthly geology. Uranium might be found in brecciated rocks, of which there were no shortage on Fram, although those rocks might preferably be rich in copper or hematite. More likely, it would be found in the eolian sandstone layer between the regolith of the surface and the comminuted bedrock.

The COIL geologists went on. “Yeah, eolianite might be best. I think about 20% of uranium on Earth comes from sandstones, although we can expect much less on Fram because it’s so much smaller and so much drier. More to the point, we wouldn’t be sacrificing the other metals we dig up. We’ll have to prospect along basal channels.”

Irrespective of where the uranium was located, we wouldn’t be digging it out with a COIL rig.

“The concentrations will be so low,” the geologist continued, “that digging enough of its out to enrich into yellowcake is a really volume-intensive endeavour. We’d be better off with an open-pit mine. In fact, we’ll take a look at the tails of the open-cut mine to the north; start prospecting from there.”

A climatologist from Alpha-1 spoke up. “And who’ll notice a little radon gas in an atmosphere already 80% poisonous?”

The conference attendees laughed.





Eyes and Ears

21 09 2009

Drone Prospector

“The MOPAD (Multiple Operation Personnel Aerial Drone), or ‘Moppet’, was designed initially as a geological survey unit to aid small groups of scientists and geologists in expeditions.  With a carbon frame, advanced photo-voltaic surface and a utilitarian onboard computer, the MOPAD quickly populated the fringes of the colonial outposts.  Trailing behind scientists and vehicle operators, they became the cybernetic pets of the new world.”

I watched a gust of wind come towards me over the regolith. Pulverised dust whipped from the tops of dunelets. The heat of the nearer Alpha B generated wind fronts which circled the planet; these were complicated by the lesser heat of the diminishing Alpha A.

I turned back to the Sprat. A line of footsteps were traced in the duricrust, from my vantage point back to Gingrich and the Sprat. Aside from the pattering of micrometeorites, this duricrust had not changed in billions of years.

Gingrich lifted a Moppet into the air; it drifted slowly upwards and away from her. It hovered at a point between Gingrich and myself, about three metres above the regolith. From my position, I could hear its soft engine.

“Where do you want to start?” Gingrich asked. Although she was maybe twenty meters from me, her voice was loud in my earpiece.

I looked at the panorama before me. I stood on the crest of a small elevation; before me was relatively flat, grey-brown regolith, stretched to the horizon. There were a series of hills off to my right and left, either formed over a basalt seam or the remains of the ridgeline marking a much larger crater.

“Well the benches need to be fifty meters wide.”

I looked at the GPS display on my tablet. This signal was relayed to me by the Moppet. The drone was connected to the GPS system directly through Port Mayflower, while also relaying a wireless connection with the Colonies’ computer over the southern horizon.

I pointed to the north, toward the far end of the elevation I was standing atop. “Let’s try up there. GPS says seventy five meters.”

Gingrich clambered back aboard the Sprat and kicked it over. She moved it north, to where I had pointed. This saved hauling the bulky seismic probe that distance on foot. The Moppet defaulted to hover above me while Gingrich drove the short distance.

Images from the growing satellite network deployed in orbit showed good signs of a vein of iron and nickel in this area. The seismic probe would confirm this, and if the vein were as close to the surface as satellite imagery suggested, an open-cut mine would be developed here.

In my ear, I could hear Gingrich groaning with the effort of unloading the A44 by herself. I turned around and looked back to the south, toward the Colonies. There was no glow of light on the horizon to mark their presence. Instead I watched a bead of light, a climber suspended on the elevator ribbon, moving slowly higher into the ruddy sky.

I held the view a moment too long.

“Come on,” I said to the Moppet. “Let’s get started.”





A Few Eggs

11 06 2007

Wounded

"…COIL mining was only a short-term initiative, at least using the MMRs. They’re very unstable machines, many parts seem faulty…or have next to nothing in the way of durability, not to mention a severe lack of safety features.

…Once the May’ gets here, we can leave these temperamental pressure-cookers to the dogs."

When we had our first accident with the MMRs, we got off pretty lightly. One of the chlorine lines burst, overwhelming the crew on the gantry stacks. We lost more than a dozen people straight away, though it could have been much worse. The chlorine or the iodine could have mixed, the oxygen by-product could have exploded, or the two components of the COIL could have met in uncontrolled circumstances and we’d have lost the whole rig.

Until the accident, we’d relied on trauma kits and first aid to deal with the injuries that cropped up: cuts, bruises, sprains, concussions, a broken leg. Suddenly we were dealing with things our e-suits couldn’t handle, or at least mitigate. Our inability to respond quickly was what cost those fifteen people their lives.

As with everything in the past fortnight, the hardware was the easiest part to fix. It’s strange to think that, a few weeks ago, all we thought of was spare parts and inventories. Sure, we still had frightening supply problems – we were all hungry from rationing, after all. And we were still on a knife-edge in terms of our capability to maintain even our basic existence, much less the expansion timetable we had for the arrival of the Mayflower.

But a chlorine line and a pump was easier to replace than fifteen of us. We weren’t Home; we’d left Home with four thousand people and, as awful as it was, our numbers where being whittled away by the harshness of our new life. Now, we were hyperaware of our own frailties, of how far from our Home we had come, of how alone and isolated we were, and of how close we were to collapsing under the weight of our own, human ambitions.

Home. Nobody called that star on the edge of Cassiopeia "Sol", not anymore. It was "Home", even for those of us dedicated to Fram and to Alpha Centauri and to seeing out what we had started here, in this place, whether that ended with the expansion of human civilization into other stars systems, or the slow death of a preemptive reach for the stars. I wonder, if we even live out the year, how many generations it will take to breed out that habit.





Alpha-4 Mining Operations

20 05 2007

COIL-MMR Operation

“…what you’ve got is a fairly ungainly machine, the COIL Mobile Mining Rig is especially difficult to move around with any precision. It was originally a tracked vehicle, but we stripped it once the grit made it more of an issue to maintain. Moves at about twenty klicks an hour, fully loaded. We’ve found it seems easier if the chemical tanks are transported separately, and it keeps the strain off the deployment elevators in transit – the thing would be useless if it arrived at its destination with a warped or bowed elevator strut…”

Chemical Mining Rig

“…automate the test burn of the COIL from the ad-hoc interface, and maintain safety protocol. Things have gone wrong with the COIL modules, so err on the side of caution. Once tested, vent the modules, deploy and connect a standard A44-10 module. Keep it on 4x scan, check it every fifteen or so. Keep it synced to your comms and store the packets on one of the drives in the modules hard disk. Commence forty-five minute bursts then wait for cool-off.”

COIL Mining Overseer - Donning Ceramic armour

“…remember to check and double-check the cleats and lining joins in the maintenance suit. Ensure every article has been inspected and cleared before use and before stowage. Also ensure the COIL module is deactivated, sluiced and syphoned from the main tank before any maintenance is completed on the rig. Watch your partner, keep an eye on the pressure and exhaust dials and keep the A44-10 cyclic to give you the heads-up if you’re about to hit something you shouldn’t…”

We kicked off mining ops at planetfall plus forty eight. That’s Solar days, of course, because no one had worked out a calendar for the crazy days Fram lived through this side of the barycenter. The first COIL MMR – we brought two – was set up east of Alpha-4, in the base of a crater named Yom Kippur where the regolith had been fused into a basalt sheet and, just ten meters beneath the surface, seismological surveys had found sublimated bedrock, fractured by the impact which created the crater. Core samples showed up lots of magnesium, aluminium, scraps of iron, and lots of fused oxygen: exactly what we needed.

It was nearly seven weeks after planetfall – two weeks since the massive operation to relocate Alpha-2 had wrapped up, and just over a month until the supply ship arrived in orbit.

The COIL was supposed to move twenty klicks an hour; Yom Kippur was only seven klicks from Alpha-4, but of course, the regolith completely frammed the caterpillar system. It ended up taking us two days to get the rig in place, including the time to strip the tracks, and to set up the refinery.

The rig was kicked off just after Alpha A had set – the only object in the sky was Alpha B, growing brighter by the week as Fram drew closer. A wind slowly kicked up after A-set. This would become more of a problem as Fram reached the extremes of its orbit: one star, whether it be B now or A in eighty years, would heat one face of the planet while the other star was too distant to heat the other. The wind was the result, great pressure systems the size of continents, as excited air particles moved from hot to cold.

Gaseous chlorine was mixed with molecular iodine and an aqueous mixture of hydrogen peroxide and potassium hydroxide. These chemicals were injected from the massive tanks, enclosed by gantries, which formed the superstructure of the rig. There was a burst of heat.

The laser burst itself was invisible, operating on infrared wavelengths. But we could see the results with each pulse: the regolith under the resonator was blown away, or fused into the basalt. With each burst, the products of the chemical reaction were separated by the rig: oxygen, water, and potassium salts were pumped away into tanks stacked at the far end of the rig, furthest from the refinery. These would be collected by the haulers and transported to the Outposts, to slowly open up the closed-loop life-support (CLLS) systems.

Slowly, the COIL rig made progress: there would be a supersonic pulse of laser energy, a blast of energy and heat, and then robotic arms would remove and sort the debris. It moved the slag off to the side, to be used later for construction of the carbon highways between the Outposts, mines, and spaceport, and the material to be processed was fed onto conveyor belts and moved down the length of the rig to the refinery.

A lot of people were standing around. It seemed as if all the e-suits in Alpha-4 were here, used by whoever could find a bureaucratic reason to be present for the deployment and firing of the Colony’s first mine. Many were searching the sky, looking for the supply ship or looking for Sol or simply enjoying the alien sky.

One of the rig’s maintenance teams had set up a sign on the upper gantry enclosing the chlorine stack; now that the rig had been firing for several minutes, a floodlight flickered on an lit up the sign. It said simply:

COIL MMR-001
brought to you by the
Engineering Corps of Alpha-4
“Keep HOPE Alive”

It was a pun – Human Outer Planetary Exploration was the over-arching term used to colonise the planets and moons of Sol in the heady days the species expanded from its homeworld. We were smiling, privately, unreadable to one another by the faceplates of our e-suits; and we all hoped the double-meaning would reach every colonist on Fram…