A, G, U and X

19 02 2012

Ngan said to Lindenmeyr: “Let me show you what we’ve learned so far.”

He moved away from the trough of methanogens and retrieved a tablet from his workbench. The tablet awoke from hibernation, and, in the reflection on Ngan’s faceplate, Lindenmeyr saw a series of brightly coloured images, rotating in imitation of three dimensions.

“If you’ll indulge me,” Ngan began, “I might ask you a question. How do you imagine alien life? How do you imagine something entirely new?”

Lindenmeyr paused for a moment.

“Is this a philosophical question?”

“Oh yes,” Ngan replied. “Imagine, if you will, a new colour. A colour no one has even seen before. Or imagine a taste you’ve never tasted. Anything you imagine in your mind is based on what you know, what you’ve experienced, what is familiar.”

“Of course.”

“We can’t possibly imagine something entirely new and different. And if we saw it, we likely wouldn’t recognise it.”

Lindenmeyr cleared her throat. “Like Stanislaw Lem.”

“Exactly.” Ngan returned to the trough of methanogens with the tablet. “The likelihood that any kind of life that evolved away from Earth would be recognisable to us, much less look like humans with pointy ears, is infinitesimal.”

“And yet we recognise these methanogens.”

“Oh yes. And here we return to that philosophical question.”

Ngan explained that the basic building blocks of life as humans had experienced it were readily and widely available in the Universe. Organic compounds such as hydrocarbons and amino acids were found in comets along with methanol, formaldehyde, ethanol and ethane, even hydrogen cyanide. The emergence of life was not some religious miracle, but rather a simple matter of chemistry – the interaction of methane, water, ammonia, hydrogen and the creation of amino acids, the building blocks of proteins.

Astonishingly, more complex nucleobases could also be formed on meteorites, asteroids and comets. Together with amino acids, these nucleobases could under the right conditions evolve into complex proteins, nucleotides, DNA.

Ngan showed a series of slides to Lindenmeyr who, although not an expert in organic chemistry, recognised the association of molecules of hydrogen, nitrogen, carbon and oxygen into an amino acid.

“So we took it back to the beginning,” Ngan said. “Because the end product is so different, we go back to the building blocks that the methanogens must have started with.”

“Ah. Now I see the point of your question. Here is the experience we use to recognise the alien.”

Ngan nodded.

“To continue with the ‘building blocks’ analogy, we figured that all life starts with the same materials and then goes about building different shapes, forms, assemblies.”

He flipped to another slide that showed a complex structure of tangled lines branching from a single curved strand. Where the tangles were clustered they grew away from the thicker strand, and bunched together like fruit on the limb of a tree.

“What is it?” Lindenmeyr asked.

Ngan chuckled. “Oh, this is the only macromolecule that composes the methanogens.”

Ngan continued and grew more animated as he explained. When tested, the methanogens had not demonstrated chirality because they were composed of neither proteins nor DNA. But here, rotating in false colours, was their analogy for both.

“It is somewhat similar to RNA,” Ngan said. “Essential for all life on Earth. In fact, viruses use RNA for genetic material. But it’s not RNA. We don’t know what to call it. We liken it to RNA only because we need that anchor of familiarity. It is only similar to RNA in so far as both are single-stranded molecules with shorter chains of nucleobases, that in turn produce some quite complex three-dimensional structures.”

Lindenmeyr turned from the spinning macromolecule on the tablet screen to the methanogens arrayed in a line between her and Ngan.

“Wow,” she managed.

“Oh yes,” Ngan replied. “At the moment, we’re half-jokingly calling it FNA.”

“FNA?”

Ngan grinned. “Framnucleic acid.”

And, arrayed around that single-strand backbone, were many of the building blocks seeded throughout the Universe: the primary nucleobases of adenine, guanine, the A, and G from DNA-based life, along with uracil, the U found in RNA; and the modified purine bases xanthine and hypoxanthine. Of these four nucleobases, FNA clustered into groups of two, rather than the groups of three into which DNA clustered.

“Actually,” Ngan said, “the simplicity of FNA is more akin to very, very early precursors to DNA than RNA as we know it. Say, four billion years ago. The precursor used only two nucleobases and a handful of amino acids, and worked well long before life evolved the triplet code it uses now. These doublets seem to work well for such a simple lifeform.”

Conspicuously absent from the image of the FNA macromolecule were thymine and cytosine, two of the nucleobases of DNA. Lindenmeyr asked Ngan why C and T were missing from FNA.

“We have a theory about that,” he explained. “Thymine and cytosine bonds are most susceptible to damage from ultraviolet light; in fact, most skin cancers from exposure to ultraviolet are a result of a thymine dimer, where ultraviolet photons damage the bonds between nucleobases and distort the macromolecule. Because of the direct exposure to ultraviolet light, we think the methanogens have evolved without thymine and cytosine.”

“A clever adaptation to the environment,” Lindenmeyr ventured, “but it cripples their genetic complexity.”

“Oh yes. Unfortunately, the methanogens won’t teach us a new way to deal with ultraviolet light; they’ve simply evolved away that part of them damaged by UV.”

Ngan brushed through the next slides. The absence of proteins dramatically simplified the process of replication, he explained. The FNA in the methanogens did not appear to articulate with a Fram version of ribosomes, and so did not communicate instructions to assemble amino acids into proteins through protein biosynthesis.

But it was so much easier to describe what life on Fram didn’t do, rather than what it did do. This difficulty was related, Ngan said, to his earlier comments about conceptualising ideas through the familiar.

Nonetheless, early work suggested that the FNA contained some amount of genetic information, but rather than communicating that information to assemble cells, the FNA duplicated itself in a manner similar to a virus; it did so, however, without a host cell. This duplication was in part related to the complex structures that the single-strand backbone of FNA allowed. The form of that structure was repeated in each duplication – limiting the opportunity to evolve, but allowing for very durable structures once natural selection identified a viable arrangement of nucleobases.

“These methanogens don’t so much ‘grow’ as they ‘self-copy,’” Ngan concluded. “We still don’t know how FNA forms these fronds, in the absence of both proteins and cells.”

Lindenmeyr turned over the fronds in her hands.

“Is it life?”

Ngan paused. “Yes and no. They are subject to natural selection, as evidenced by the absence of thymine. They possess analogues of genes. But they grow through self-assembly, rather than cell division.”

“Life,” Lindenmeyr said again. “Wow, I don’t even know how to communicate what I’m trying to say. I mean, we’re life, you and I, and we evolved from amino acids and nucleobases, and we go out into the Universe and we find these methanogens, and we stand here in this room and…and life asks if life is life.”

Ngan chuckled.

“Oh yes. I think of it like this: spread around the Universe are kits containing all the parts to make something. But there are no sets of instructions, no recipes, in these kits; not even someone or something to assemble the parts.”

Lindenmeyr nodded. “That’s the magic, I think. As best they can…the kits assemble themselves.”

Ngan spread his hands.

“And here we are.”

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Ultraviolet

8 02 2012

The effect of the gravities of two stars upon Fram’s orbit was quite pronounced.

Fram’s orbit was highly eccentric, meaning that it was a not a simple circle around Alpha B, but rather an elongated ellipse. Traced simply, Alpha B sat inside one end – called an apsis – of that ellipse, while the other apsis stretched away toward Alpha A. But neither Alpha A nor B were stationary, and themselves orbited a mutual barycentre. Their own orbit greatly complicated Fram’s orbit. The apsides changed with each orbit relative to the position of both stars. This was called apsidal precession. Each time Fram completed an orbit of Alpha B, Alpha A had moved relative to its binary partner, and its gravity tugged at Fram. As a result, each completed ellipse reorientated itself toward Alpha A.

Astronomers explained apsidal precession by tracing a complex spiral that represented Fram’s orbit. The lines of that spiral converged at periapsis – the apsis that coincided with perihelion, Fram’s closest approach to Alpha B – but diverged in wandering arcs near aphelion, as each orbit traced a different apoapsis. Fram was moving away from periapsis and, slowly, methodically, irrevocably, gliding toward apoapsis. Fram had only in the last week passed periapsis, and took roughly three Earth years to complete an orbit, meaning that the apoapsis of that orbit was about eighteen months away.

There were many concerns about the habitability of Fram, almost all of which had been foreseen and discussed long before the Quoqasi left Sol. Only one among these was its wandering orbit, which itself posed the major problem of exposure to ultraviolet light.

Alpha B was less of a concern than Alpha A. Alpha A was larger, hotter and brighter than Sol, while Alpha B was similarly smaller and cooler. We knew that hot objects preferentially emitted radiation at shorter wavelengths and higher frequencies. Wien’s displacement law described the relationship between temperature and peak frequency. The hotter the object, in this case a star, the shorter the wavelength at which it emitted radiation. This was why hot, A-type stars like Sirius tended to emit blue light in the visible spectrum, while cooler M-type stars like Proxima tended toward red light.

But visible light was only one component of the electromagnetic spectrum. Higher up the spectrum according to frequency were ultraviolet, x-rays and gamma rays. Hotter stars not only pumped out more light, but also preferentially emitted these higher frequency, shorter wavelength types of electromagnetic radiation.

Not only did Alpha A pump out more energy than both Sol and Alpha B, but it also preferred to emit more dangerous energy.

Humans had evolved while sheltered from most ultraviolet radiation by Earth’s ozone layer, a belt of the stratosphere where the interaction of molecular oxygen and solar ultraviolet light continuously interconverted oxygen from O2 to O3; the process also converted ultraviolet radiation into thermal energy. But Fram, of course, possessed no ozone layer. Almost all of the oxygen in Fram’s atmosphere was covalently bonded with a carbon atom to form carbon dioxide, which was not only poisonous to breath but offered no shelter from ultraviolet light.

From Earth, it was easy to miss some of the features of Fram that would challenge our early efforts, such as the damage that the regolith would pose to our vehicles and equipment. But it was comparatively simpler to understand the stellar system, and we were prepared for the worst of the ultraviolet light. Equipment at risk of UV degradation, like synthetic polymers, had been reinforced with stabilisers and absorbers – such as benzophenones, zinc oxide, and titanium dioxide. Moreover, the same lack of independent oxygen in the atmosphere that prevented the development of an ozone layer also suppressed the reaction between ultraviolet rays and free radicals that led to the worst of polymer degradation.

All of these measures would be tested at apoapsis, when Fram was suspended between the two stars and at its closest approach to the more threatening Alpha A. At that point there would be no real night, but rather a bright twilight, the sky dark blue and the terrain of the planet lit with a quality of light like the totality of a solar eclipse on Earth. Exposure to ultraviolet would be highest at apoapsis.

Some of the biologists noted the similarity of the colonisation of Fram to the emergence of life on Earth. Early prokaryotes approached the surface of Earth’s oceans billions of years ago, before Earth had developed an ozone layer, and, exposed to the worst UV light, promptly died out. Those that survived had developed the necessary enzymes, base excision repair enzymes, which identified and corrected the genetic damage caused by exposure to ultraviolet.

And so, as Fram continued gracefully along its complex orbit, we began to study how the methanogens had evolved to tolerate such intense ultraviolet light…





Convergence, Part Three

3 11 2011

And so, the planetary systems of the two Main Sequence stars of Alpha Centauri came to settle into a tenuous equipoise. Proxima Centauri, Fram, Belgica and Maud, their moons, the asteroids of the inner system and dwarf planets and KBOs of the outer system, circled about Alpha Centauri A and B for four and a half billion years. So too did Alpha Centauri A and B circle about the Milky Way as the entire Galaxy spun like a pinwheel, its spiral arms trailing away from the direction of its rotation. And the Milky Way interacted with the Local Group, and was pulled with the accelerating expansion of the Universe.

It was a stasis of silent, sure, sweeping movements.

In that silence, a narrow and forever imperilled form of life emerged. The impact of comets and carbonaceous chondrite asteroids gave the moon that humans would one day call Amundsen a burgeoning atmosphere, and, with that carbon dioxide, carbon monoxide, methane and ammonia, deposited organic compounds, long-chain hydrocarbons and amino acids. While the planets and moons spun in mean motion resonances, these compounds evolved into a primitive life that consumed carbon dioxide and hydrogen and produced methane.

These methanogens, exceptional and precious and delicate though they were, would never look at the stars and give them names; would never write equations to explain the motion of the planets; would never manipulate the fundamental building blocks of the Universe and use that knowledge to propel themselves across the gulf between stars. For two billion years these methanogens evolved in complexity and function from those cometary hydrocarbons – and then their evolution plateaued, unable to expand from their niche. Fragile fronds caressed the thin air of Amundsen with neither mind nor purpose.

When Amundsen’s surface was shattered by a devastating impact, these methanogens rode debris to the surface of Fram, and, in the overabundance of Fram’s dense carbon dioxide atmosphere, thrived and exploded in numbers.

By contrast, the life that had evolved on Earth was diverse and abundant. It had likewise taken billions of years to evolve, but had done so in an environment of plentiful oxygen, which readily bound with the structural molecules of living organisms – carbohydrates, proteins – and, as an oxidiser, was an energetic component of cellular respiration. Fuelled by oxygen and liquid water, simple cells blossomed over almost four billion years into multi-cellular life; and, in a burst of less than half a billion years, arthropods, fish, plants, and insects appeared; and then, over another 150 million years, reptiles, mammals, birds. After a series of extinction events and periods of climatic change, humans appeared, roughly recognisable after 4.2 billion years of evolution, and certainly within the last 200,000 years as the species that would spread among the stars.

In the space between chords of the musica universalis, humans began to communicate and share knowledge, and to congregate in settlements and farm the lands around them; through agriculture they developed empires and republics and began to speculate about the Universe in which they had evolved. In a flicker of time imperceptible to the patient stars, humans spread across the face of and came to rapidly dominate their planet, first split and then fused the atom, walked on their Moon, developed radio telescopes and studied the stars. As they did so, humans imparted upon the Universe both mind and purpose.

They searched for other worlds like their own. At first they listened to the stars for radio messages, assuming that life had evolved elsewhere as humanity had, and that this life would communicate in the same way that humanity did. They then used increasingly sophisticated technology to monitor the brightness of stars, watching for the transit of planets across the face of those stars; measured the movements of those stars to determine the gravitational influence of large planets upon their star; and, with orbiting space observatories, developed telescopes that could eventually resolve individual planets light years away.

Despite their relative proximity to Sol, Fram and Belgica evaded easy detection. Both were small planets, and many of the methods were biased toward the detection of large gas giants. Belgica orbited close to Alpha Centauri A, and was, at a distance of over four light years, indistinguishable from the light of its parent star. And Fram’s slow, elliptical orbit did not frequently transit the face of Alpha Centauri B – and, when it did, it did so quickly, as Einstein had theorised of an object that moved deeper into the curvature of space-time created by a massive body.

Nonetheless, observations of other stars encouraged humans to believe that small, undetected worlds orbited their nearest neighbours. They sent sophisticated, robotic probes to the closest stars, even as they exploded in number and expanded from their damaged homeworld to colonise the nearest planets and moons of their solar system.

Thus, decelerating from nine-tenths light speed, a robotic mind appeared in the Alpha Centauri system, and reported to the distant minds that had evolved in nearby Sol. This probe noted Fram, noted also its atmosphere and magnetosphere, concluded that human settlement would be possible upon its surface, compiled a report detailing these conclusions to relay to Earth. And with the receipt of those conclusions, two separate star systems – which had, perhaps, in the distant past formed from the same molecular cloud, but which had developed in vastly divergent ways – enjoyed the beginnings of convergence.

Alpha Centauri A and B had not completed two orbits of their mutual barycentre in the time between the arrival of the first, primitive, crackling radio signals from Sol and the arrival of the first interstellar starship. Immediately, the colonists borne from Sol by that ship went to work making Alpha Centauri their home. Intelligence evolved of another star, but an intelligence nonetheless, came to explore and appreciate Fram. Philosophers among those colonists would ask whether Fram had even existed before colonisation, without a sentient, rational mind to observe its orbit, the movement of regolith across the duricrust, the disintegration of Amundsen.

And, then, the life which had come so recently to Alpha Centauri discovered the life that had in so limited a fashion evolved there. At that point, two divergent paths taken by the Universe toward the emergence of complexity, separated by five billion years and four light years, converged…





G, C, A and T

4 08 2011

“I really had no idea,” Lindenmeyr said. “It’s so…alien.”

The breather unit strapped across her mouth and nose muffled her voice. She stood across from the leading molecular biologist of the colonies. They were standing in a geodesic greenhouse, an igloo of polymers and plastics, connected to Alpha-2’s hydroponics shed by a tented walkway. Regolith had built up on the windward side of the igloo.

The molecular biologist was also head of hydroponics for Alpha-2, Lindenmeyr’s counterpart, and he was an ebullient man in his fifties named Ngan. He ran his hand over a frond of the methanogen. The alien plants were lined in a nutrient trough not unlike the lettuce and soy that Lindenmeyr so delicately tended each day; these plants were, however, immersed in a solution of hydrates, and existed in an atmosphere of carbon dioxide and methane.

“Oh yes,” Ngan spoke eagerly. He chuckled. “Very alien. You don’t know the half of it.”

“Even the name,” Lindemmeyr ventured, “is anthropomorphic.”

“Oh yes.”

Buried deep within Earth’s mantle, microbial communities existed that were almost entirely isolated from the rest of the planet’s biosphere. Within those depths, hydrogen was dissociated from water by heat and pressure and radioactivity, and this hydrogen combined with dissolved carbon dioxide and powered the microbial biomass, which metabolically produced methane. These were the methanogens after which we had, somewhat unimaginatively, named the biomass of Fram.

Lindenmeyr ran her bare fingers through the fronds. The texture of the plant was more like soft rubber, or maybe putty; it offered an unnerving resistance to her touch. On closer inspection, she could see that these fronds were in fact wide, tube-like structures, fatter at their base but which inevitably narrowed into a mouth at the tip.

“The methanogens on Earth,” she said, “they’re microbes. They could be studied only through a microscope. This I can touch, feel, plant.”

“Microbial methanogens,” Ngan said, referring to the Terran variety, “are thermophiles. They thrive on heat. By comparison, these methanogens are psychrophiles. That they live through Fram’s winters speaks to their extreme tolerance of cold.”

“Should we even be calling them ‘methanogens’?”

“I don’t see why not. They produce methane from carbon dioxide and hydrogen, just as their microbial counterparts do. And both are extremophiles.”

“But comparisons end there,” Lindenmeyr prompted.

On Earth, all life emerged from the same soup of primordial microbes, three or four billion years ago. This emergence was the spark of life, a miracle, a random assembly of strings of amino acids into coherent structures that spawned nucleotides, proteins and enzymes – a moment of such unimaginable unlikeliness that humans would later deify it and call it Genesis. From that point, life blossomed and developed and was subjected to the pressures of evolution, and diversified into the branches of the tree of life.

We know that all life came from the same point of origin because all the life on Earth – humans, bacteria, tomatoes, pigeons, everything – shared the same structure and were organised by the same system. DNA and RNA stored information; proteins and enzymes composed structures; adenosine triphosphate (ATP) released energy. Identical genes were found in vastly divergent species – although organised in different structures, humans shared 63 percent of their genetic material with mice and 38 percent with yeast.

From the data stored in DNA, genetic code translated instructions for ribosomes to make proteins by stringing together amino acids in a determined order. The information was stored as molecular units named nucleotides; there were four different nucleotides that were labelled G, C, A and T based on the nucleobases guanine, cytosine, adenine and thymine. What distinguished Lindenmeyr and Ngan from their childhood pets or from the soya they drank that morning were the sequence of those letters. DNA grouped these nucleotides into clusters of three: there were sixty-four different possible triplet combinations that together specified twenty-one different types of amino acids. There was a huge range of possible permutations of nucleotides and amino acids, and it was this range that generated the enormous, diverse, elegant abundance of life on Earth.

All life on Earth used these structures to exist.

“Before we even got to a genetic profile, we knew something was different,” Ngan said. “You know that microbial methanogens use chemiosmosis to generate ATP, where hydrogen is the reducing agent and carbon dioxide is the substitute electron acceptor in the absence of oh-two.”

“Anaerobic respiration, yes.”

“Well, the methanogens on Fram don’t produce ATP through chemiosmosis. At first we thought that they produced ATP through oxidation of carbohydrates, with an endogenous electron acceptor, maybe sulphate…”

“Wait,” Lindenmeyr said. “Fermentation?”

“Oh yes, that’s what we thought. Based on these tube-like fronds and these plants’ preference for carbon dioxide and hydrogen. But it seems that these methanogens, well, they don’t produce ATP.”

“Umm.”

Botanists had subjected the Fram methanogens to the Levin test, a labelled release of two liquids, one of sugars and the other of amino acids. The test was to determine chirality, the preference of genetic material for right-handed sugars or left-handed amino acids. The tests reacted equally to both mixtures, suggesting a chemical rather than biological reaction.

“My god,” Lindenmeyr whispered. “There’s no chirality. No right-handed DNA spiral.”

“No,” Ngan replied. “Because there’s no DNA. No ATP. No nucleotides. This is alien life, Vetsera.”

Lindenmeyr took a moment.

“Even so, it’s pretty god damned alien.”

“Oh yes,” Ngan chuckled. “Let me show you what we’ve learned so far…”





Panspermia

26 04 2011

Dozer

“The Remokon-90 “Dust Devil”, a quad-tracked pinnacle of autonomous microwave-grading technology, ushered about a new age in what had been previously been labour-intensive and dangerous expansion efforts by the colonists of Fram.  Fed telemetry and geological scans, the Dust Devil worked around the clock turned vast tracts of uneven lunar terrain in smooth, glass-like foundations.  The Remokon-90’s onboard computer could be accessed and remotely controlled, but due to its rugged performance and impeccable results, many of Fram’s large-scale terraforming become the realm of robotics.  Thanks to the Remokon-90, any project involving automated machinery was henceforth affectionately known as “the devil’s work”.

Chesney bounded across the surface of Amundsen in long, loping strides.

Both stars had set, but the light of half-illuminated Fram lit the surface of the moon. It was a strange, muted light, a light that evoked childhood memories in Chesney of the thick smoke of wildfires and the twilight of a sun choked by ash and soot.

To her right was Wisting Base and, beyond that, the straight shadow of a rille defined by its far horst. Rising over these was the crescent of Fram and, curving around the edge of the disc like the bow of a parenthesis, the highlighted arc of the planet’s ring.

As Chesney looked into the light cast from the ring and planet, the regolith which covered the visor of her helmet caught the light. She reached for the soft-bristled brush hooked to her belt; she could not easily brush the particles away with her glove without scratching away the visor’s protective coating.

Ahead of her was the Dust Devil, a ’bot the size of a tank, motionless and dark.

Chesney worked her way toward the Dust Devil parallel to the runway. There was little to this runway, yet – maybe a hundred meters of glazed regolith. This glossy, dark grey path stretched past Wisting Base and ended at a point beneath the Dust Devil. Chesney carefully loped around the recovery equipment for the CATOBAR system: the cylindrical shapes of friction brakes and several coiled arrestor cables. These lay assembled to the side of the runway, and some pits had been dug for the brakes and their motors; but the recovery system was not yet ready to be installed.

“What do you see, Chesney?”

Chesney winced. She looked over to Wisting Base, watched a rover move over the far rille toward the collection of pressurised cylinders, imagined her mission commander watching her on the monitors of the control room.

Martinet.

“I can’t see anything moving.”

Which wasn’t entirely accurate; regolith cast up by the Dust Devil was still settling on either side of the vehicle, falling in perfect, slow parabolas in the moon’s negligible gravity.

“I’ve tried remotely resetting the firmware,” the voice in Chesney’s earpiece stated. “Still getting the same error.”

As Chesney approached the Dust Devil, she saw that the grounding pitons had fired: at points along the length of the vehicle, wires had shot from the Dust Devil into the lunar surface.

“The electrostatic pitons have fired,” she reported back to control.

As the Dust Devil ploughed through the dry regolith it built up a significant tribolectric charge; insulted by the regolith and existing in a vacuum, this charge could not be easily grounded. When in standby mode the Dust Devil deployed these pitons to discharge the electrostatic build-up into the bedrock, where there was a higher proportion of conductive iron.

Nevertheless, as Chesney reached out to place gloved hand on the vehicle’s caterpillar track, there was a brief arc between her hand and the dusty track. She instinctively pulled back her hand.

It took a moment for her suit’s systems to respond, and, during this time, the mission commander’s voice was lost in a wash of static.

“I’m fine,” she said.

She ran her hand over the rear fantail, a bridge suspended between the larger rear caterpillar tracks in which were installed a series of magnetrons. Chesney pulled down a hatch that revealed a hibernating terminal; she awoke this terminal and established a wireless connection with her tablet. She immediately began to run diagnostics on the magnetrons.

“Start with the magnetrons,” the mission commander instructed. “Start with a series of diagnostics.”

Chesney rolled her eyes but held her tongue.

Three rows of magnetrons pointed downward from the Dust Devil’s fantail, and these fired microwave energy into the regolith beneath. At the right power and frequency, these microwaves sintered the regolith and fused it into a half-meter thick seam of lunar glass. This glass was like an artificial basalt, and would, once complete, provide a good foundation for Wisting’s landing strip.

The process relied upon the high level of iron in Amundsen’s otherwise silicate regolith. Deposited here by billions of years of micrometeorite impact, these nanometer-scale beads of pure iron efficiently concentrated the Dust Devil’s microwave energy and heated up the surrounding silica, sintering this loose dust into large clumps and, eventually, solid structures.

Where the Dust Devil had inexplicably halted its programmed sweep, the sintered regolith was thin and cracked easily beneath Chesney’s shifting feet.

“I’m getting nothing unusual from the magnetrons,” Chesney reported. “I’m leaving the system to run a clean-up, but the diagnostics showed nothing.” She clipped the hatch and precluded what she knew would be her commander’s next comment. “I’m heading forward to inspect the dozer and guidance systems.”

The Dust Devil had four large tracks arranged in two sets of two. Set between the forward tracks was a simple dozer blade that levelled and compressed the regolith before it was sintered by the microwaves. Above the dozer was an elevated fin that resembled the twin tailbooms of an aircraft; within this blade were the Dust Devil’s guidance systems: ground radar, forward-looking infrared cameras, electromagnetic and visual spectrum sensors, and path planning intelligence.

Here again Chesney ran a series of wireless diagnostics. She accessed the firmware’s log, and found the same error message as that relayed to the control room.

“Yes, that’s what I’ve got on this end,” the mission commander dryly noted.

“It’s like it’s gone into sleep mode.” Chesney placed her tablet delicately on the upper surface of the guidance fin. “Can you check the program logic from there? Under what criteria would the Dust Devil shut itself down?”

“Mmmhm. While I’m doing that, check the dozer blade.”

With some difficulty Chesney crouched on one knee, bracing herself against the caterpillar track so that she didn’t bounce off the regolith in the low gravity. Like a ship riding a bow wave, the angled dozer blade had ploughed deep into the regolith, and banks of dust had piled on either side. Within these piles there were a few larger, brecciated rocks, but none large enough to halt the Dust Devil.

Chesney absentmindedly picked up one of these larger rocks; saw that while it was fractured it was not a breccia at all; realised that it was striated, igneous basalt. She frowned. Intersecting the banded strata, however, Chesney noticed an imperfect but regular zig-zag; she held the rock up to Fram’s light and saw that these lines were impressed into the rock.

“Oh my God,” she whispered.

Chesney slipped the rock into a sample bag on the thigh of her suit, excitedly ran her fingers through the regolith around her. She found a number of striated basalt pieces, each with the same faint impressions. Chesney’s heart thumped. They looked like adpressions. Common plant fossils. And the shape of the fossils reminded her of the anaerobic methanogens on Fram.

“Those shutdown protocols,” she gushed excited into her mike, “do they include detecting something…biological?”