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…”





Wings over the New World

1 08 2011

SookyBird

“…the newly-formed Special Aeronautics Department began as a small collection of office modules and scaffolding atop Alpha-1.  Their crowning achievement was taking the powerplant of a Sprat and turning it into the SAD-1, or ‘Sookybird’ as it came to be known.  A light, powered glider; manned by a single pilot and fired via a magnetic slingshot from a specially-designed flight gantry.  It was as much an exercise in raising the spirits of the colonists as it was a technical achievement.”

After the murder, we came to appreciate the limitations of satellite photography.

Cane had disappeared into that vast area beyond the colonies and seismological relay stations that we had slowly come to call the Periphery, and neither satellites nor trackers could find him. Only weeks later had a long-range team chanced upon the degrading, short-range beacon of Cane’s vehicle.

Satellite mapping of Fram was an ongoing task. We had since Planetfall mapped a swath of Fram, centred on the equator and ranging between twenty and twenty-five degrees north and south latitudes. We had accomplished this with only two satellites, locked in opposing orbits. There were, of course, over a dozen different satellites in orbit of our world, but most of these were space observatories examining the Universe in various wavelengths, or monitoring the Amundsen Ring for potential impactors.

Yet the ground resolution of the images provided by these mapping satellites was in some cases insufficient for our needs. There were other limitations beyond low ground resolution. The manoeuvrability of satellites was restricted to their planned orbit, in turn circumscribed by delta-vee and payload. Because of this, data collection was slow, as evidenced by the limited coverage of Fram’s surface achieved in the months since Planetfall. Data collection was also dependent on weather, and, although cloud cover was less a restriction on Fram than the worlds and moons of Sol, dust storms were common, and in the polar latitudes these storms were violent and long-lasting. Moreover, our pool of satellites was limited to those brought from Sol aboard the Quoqasi and the Mayflower; although we could potentially build more, the costs of construction and launch were prohibitive.

Thus, we turned to cheaper alternatives to supplement the data collection of satellites. Two contending alternatives were submitted to the Special Aeronautics Department: an unmanned aerial vehicle, and a low-altitude, manned aircraft. Various designs for each alternative were explored, from fixed-wing aircraft to VTOL rotorcraft, to airships, to both autonomous and guided UAVs. Almost every design responded to Fram’s thick atmosphere with differing wing shapes. Some of these shapes appeared to the eyes of creatures that evolved on a world of comparatively thin air as impossible, or delicate, as though no lift could possibly be imparted on such a shape. The most creative of designs was for a UAV with sets of wings like those of a dragonfly which, through a complex motion calculated to reduce drag, paddled through the air.

Fram’s atmosphere imposed further limitations. Its thickness provided more lift, certainly, but that density also required more of the aircraft’s engine for propulsion. Designers looked at jet engines, fuelled by SiH4, an oxidiser that readily burned in a carbon dioxide atmosphere. But silane was both difficult to manufacture and extremely toxic. Other methods of propulsion were examined, and these methods would be balanced by the requirements of power and endurance.

The advantages of a low-altitude photographic platform were readily apparent. Ground resolution would be increased, and data collection would be less constrained by weather. The ability to follow more complicated flight paths offered the geologists a better perception of the depth and scale of geological features; while increased resolution would help the xenobotanists identify clusters of methanogens. Moreover, these platforms offered real-time data – which would become important for search-and-rescue as we grew outward from the colonies and further explored our world.

And so there was some amount of compromise behind the accepted design: the SAD-1. It was a manned vehicle, which reduced its endurance, but also reduced the complexity of its design. The Special Aeronautics Department accepted that endurance was less an issue while the Colonies remained young, as most of the SAD-1’s work would be within two of three hours’ flight of its airbase atop Alpha-1. It was powered by solar-electric cells that lined the surfaces of its wings, and these electric cells could be powered by lasers beamed from the surface. The SAD-1 was propelled by two turboshaft engines mounted in the bases of its wings, which produced free turbine shaft power that spun rear-mounted propfans. Flanking the fuselage was a sophisticated sensor suite of electromagnetic spectrum sensors – infrared, ultraviolet, microwave – laser spectroscopes, and geomagnetic sensors. Mounted beneath the SAD-1’s fuselage was a super-wide angle camera, composed of four digital cameras mounted in overlapping optical axes.

At some point along the length design process, the name ‘Sookybird’ was attached to the SAD-1, and by the time of its maiden flight that moniker had stuck. The vehicle was launched from the upper heights of Alpha-1 using the same kind of electromagnetic catapult installed at Wisting Base on Amundsen. There were sparse crowds of interested onlookers, mostly colonists of Alpha-1, gathered along the ridge of the crater. Not many of those gathered appreciated the irony that the Sookybird’s first high-resolution mapping mission was of the Henderson Ridge, where Cane had murdered his partner and vanished into the Periphery…