Aurora

by Kim Stanley Robinson

  The settlers rolled slowly across the land, averaging 655 meters a day, with their longest day only three kilometers, and that between two troughs, over flat burren. It took them twenty-three days to move their settlement to the sea cliff overlooking Half Moon Valley, on the shore of the western sea. They had traveled by the light of Planet E as it went through its full phase, a huge sight; they noted the lunar eclipse in the middle of that, the shadow of Aurora diffusely crossing the face of E, dimming it somewhat, but not too much, because E was so much bigger than Aurora, and the two so close together, and both with thick atmospheres, which diffused Tau Ceti’s light around Aurora and meant E was not very shaded by it. After that they had scarcely noticed the dimming of E’s slow wane, which brought back in the lambent night more blurry stars. These stars slowly shifted overhead, and the phases of E also shifted, but E stayed always fixed in place over them, a bit south and east of the zenith. Some settlers said this felt strange; others shrugged.

  Near the end of their trek, they waited out a hard rainstorm, when it got too dark and wet to travel safely. And they stopped work to witness the sunrise of Tau Ceti, painfully bright over the burren to the east. Like a nuclear explosion, some said, in what was perhaps a false or mistaken metaphor, as it was in fact a kind of nuclear explosion.

  Though they could see down into their ocean valley, they were still on the cliff above it, and so had to bulldoze a ramp road down the side of the river canyon that formed the largest break in the sea cliff. This tilted curving road was the work of another eight days. When it was finished, they drove all the vehicles down to the valley floor and located them near the bottom of the cliff, on an alluvial floodplain near the river. This was clearly going to be the spot in the valley best protected by the cliff from the winds. At least the offshore winds.

  As they quickly found, there were times when the winds poured up and down the river canyon even faster than they had out on the burren, as the gusts were channelized by the canyon. Once this became clear they moved their caravan farther from the river, and got some protection at the foot of the cliffs about two kilometers from the canyon mouth. This was a relief to all. Their new location seemed the best they were going to be able to find in this region of Greenland, all things considered. So they began to settle in at the foot of the curving cliff, and later in some steep, short gulleys that ran up the cliff to the burren. These ravines were transverse to the prevailing winds, and therefore well protected, but mostly steep-walled, with narrow floors.

  To aid the wind break of the cliff, they began to build what they called city walls out from it. One would encircle their residential complex, and another one, longer still, would enclose the first fields they hoped to plant in the open air.

  Every day there was more to be done than they could do, and they welcomed the regular infusion of people who started coming down again from the ship. They jammed these newcomers into the shelters as tightly as they could manage. Everyone ate food sent down from the ship. They kept the printers on both Aurora and the ship working continuously, making all the parts they required to assemble their new world. In this process their feedstocks and simply time itself were the only limiting factors. They couldn’t make more time, but they could send mining expeditions out onto the burren to locate metal ores and replenish their feedstocks, and they did.

  More people descended, bringing them to just over one hundred total. Greenhouses now became crucial. They hoped eventually to grow crops out in the open air, and the chemical composition of the air was adequate for this, indeed nearly Terran; but during the nine-day nights, despite the waxing and waning light of E overhead, the temperature dropped to well below freezing. It wasn’t obvious how they were going to solve that, in regard to their agriculture. There were winter-tolerant plants that cold-hardened and went dormant, and survived freezes; the farm labs on both ship and Aurora were investigating how these plants accomplished that, and whether the genes for that ability could be transported to other plants. Also they were looking into genes that could help plants adapt to the daymonth cycle rather than annual seasons, but the outcome of this effort was not clear. For now, whatever they ended up planting, greenhouses were necessary.

  At first most of the greenhouse space was given over to growing soil itself. Soil as opposed to dirt was about 20 percent alive by weight, and plants were very much happier growing in it than they were in dirt like the valley’s dead loess. When they had viable soil, which fortunately grew in tanks filled with loess at nearly the speed of bacterial reproduction itself, they spread it in the greenhouses and planted crops. These were mostly fast bamboos at first, bamboos they had nursed throughout the long voyage to Tau Ceti without much needing them; now they came into their own, as they were a crucial building material, providing strong beams at a growth rate of a meter a day. Meanwhile the settlers’ food still came mostly from the ship and was flown down to them.

  This created another supply problem. They had robot ferries capable of flying down from the ship to Aurora, then refueling and launching to get back up to the ship, but they needed fuel. One of the factories in the valley was entirely devoted to splitting water into oxygen and hydrogen, the main components of their rockets’ fuel. The factory itself had to be powered, however, and splitting water was very energy-intensive. They had two powerful nuclear reactors with them on the surface, providing 400 megawatts total, but the uranium and plutonium in the reactors would not last forever, and the ship’s supply was only adequate for the ship. Was there uranium on Aurora? According to standard theories of planetary formation, there had to be some; but the entire Tau Ceti system was less metallic than the solar system, and heavy metals only accumulated well on planetary bodies with a steady churn of tectonic action or tidal flexing. It wasn’t clear Aurora had ever had either, and given the uncertainty on this point, it was felt that they were going to have to devote a good deal of their manufacturing capability to building wind power generators on the burren. For sure there was going to be enough wind.

  The people in the new settlement named it Hvalsey, after a town on the west coast of the Greenland on Earth. Quickly they expanded around the greenhouses. Stonecutters and foundries provided stone blocks and aluminum sheeting for construction, also glass windows for greenhouse roofs and walls. The city wall helped solve the wind problem. Some said Hvalsey looked like a little medieval walled town.

  They were finding that the winds shifted in a somewhat predictable way through the course of the daymonths. When the air above a region was lit by Tau Ceti for nine days straight, it heated and rose, creating low pressures on the surface that cold air from the night side rushed in to fill. Then when sunset arrived, and a region was in night for nine days, it cooled down so drastically that snow and ice appeared on all the islands, and sea ice covered the calmer bays and reaches of the ocean, but not usually on the open sea, which was too buffeted by waves and wind to freeze over. The cold air in falling created pressures that shot out to the sides, filling the relative gap under the rising air on the sunlit side. So the winds were always swirling, mostly from night to day. Midday and midnight appeared to be the calmest times.

  The long nights over the inner hemisphere never became quite as cold as those over the outer hemisphere, but they still dropped to well below freezing. If they were going to do agriculture in the open air, they were going to have to adapt their Terran plants from an annular to a monthly temporality. Watching their fast bamboo grow a meter a day, it seemed possible that they could engineer crops to grow to harvest in nine days, but no one could be sure how that would work, or even if it was possible. If they had to confine their agriculture entirely to greenhouses, it seemed like a fairly serious constraint. But they would cross that bridge when they built it, as Badim put it.

  Meanwhile, in terms of the wind, which kept forcing itself to the forefront of their attention, the monthly air flows were regular, but not entirely consistent. They had a very sensitive dependence on conditions that were always changing. But
as they learned more about Aurora’s weather, they began to identify certain patterns. One thing was perfectly obvious: on most days it was going to be windy.

  E’s year was 169 Terran days long. The Auroran month, 17.96 Terran days long, therefore divided into the solar year of 169 days to create about 9.2 months a year, and thus the usual problem of trying to reconcile lunar months to solar years.

  They did not worry about that now.

  With the town walls under robotic construction, and the platting of the town finished and building sites being prepared, Euan frequently joined the teams going out to explore the sea valley. And he wanted to take off his helmet and breathe the ambient air.

  This came as no surprise to Freya. The data from the monitoring stations were making it clear that Aurora’s atmosphere was breathable by humans, that indeed Aurora’s atmosphere was the most Earthlike aspect of their new home, and the main reason it scored so high in Earth analog rubrics. So as he joined all the scouting expeditions he could, Euan pushed harder and harder for official permission to take off his helmet. “It’s going to happen sooner or later,” he said. “Why not now? What’s keeping us from it? What are we afraid of?”

  Of undetected toxins, of course. This was what he was told, and to Freya the caution was obvious and justified. Poisonous chemical combinations, unseen life-forms: the precautionary principle had to guide them. The Hvalsey council insisted on it, and also referred the question to the ship’s executive council, who said the same thing.

  Euan and others of his opinion pointed out that their atmospheric and soil and rock studies had now gone right down to the nanometer level, and found nothing but the same volatiles they had detected from space, plus dust and fines as expected. The atmospheric gases were much like the air in the ship, except slightly less dense. Studies on the ground had confirmed the abiologic explanation for the oxygen in the atmosphere; they could even estimate its age, which was about 3.7 billion years. Tau Ceti, brighter then, had split Aurora’s hot ocean water into oxygen and hydrogen, and the hydrogen had escaped to space, leaving the oxygen behind. The chemical signatures of that action were unambiguous, a finding that had reassured the biology group that they did indeed have the place to themselves, as indicated by everything else they had seen.

  Euan wanted to start that part of their new history, the first moment of going outdoors and breathing the open air. Freya said this to him during one of their conversations, and he replied, “Of course! I want to feel that big wind fill my lungs!”

  The executive council continued to ignore the biology group and to refuse permission, to Euan or anyone else. Once the seal was broken between themselves and Aurora, there would be no going back. They needed to wait; to experiment on plants and animals first; to be patient; to be sure.

  Freya wondered what Devi would have said about it, and asked Badim what he thought, but he only shook his head. “I’m not sure,” he said. “She was both cautious and bold. What she would say about this, I just don’t know.”

  The executive council asked the security council to consider the matter and make a recommendation, and the security council asked Freya to join their meeting. Badim said the invitation was because of her friendship with Euan. The committee members were worried about him in particular.

  The security council met to take up the question. Freya said to them, “I’ve been trying to imagine what Devi would have said about this, and I think she would have pointed out that the people on Aurora have had to take shelter in buildings they constructed by cutting stone. They’ve faced the stone with diamond sprays and aluminum, but there have been periods in the construction process when they’ve been exposed to cut stone. That isn’t exactly the same as going out into the open air, or jumping in the ocean, but it is exposure of a sort. So is going outside in suits and afterward going back inside still wearing the suits, and taking them off. What I mean to say is, inevitably they are already in contact with the planet. As soon as they landed, exposure was inevitable. And when they went out onto the surface in suits, even more so. They couldn’t stay inside a hermetically sealed chamber, they’re in contact with the place. And that’s good, right? That’s where we all hope to be. And nothing has happened to them, and they’ve been down there for over forty days. So keeping them confined indoors or in their suits is a conservatism that doesn’t conserve anything. It doesn’t acknowledge the reality of the situation. And it’s always better to acknowledge the reality of the situation. This is what Devi would have said, I think.”

  Aram nodded at this; Song too nodded. If their system of governing had been a direct democracy, it was likely that the people on the surface would have been allowed to go out and open their suits and let the wind fill their lungs. But their government was made up of councils that for many years had often selected their own members, in effect. The ship’s computer was advisory only, and the ship tended to be conservative in matters of risk assessment and risk management, in ways everyone had seemed to want from it. So its programming seemed to indicate.

  Now the security council again voted to keep the settlement closed off from the ambient environment, and those voting for this included even Aram and Song. The executive council did the same. But the time seemed near when that might change.

  Down in Hvalsey, they were having more trouble dealing with the winds. Through the long morning of the daymonth there was a steady offshore wind of about fifty kilometers per hour, with gusts as strong as a hundred. There was a slight katabatic effect coming off the sea cliff that made the river canyon particularly windy. At middaymonth, during the strange darkness of the solar eclipse, there was a period of slackening winds, and then of comparative calm, and everyone on the surface (126 people now) wanted to get out in this calm time, which could last past the end of the eclipse for as much as twenty or thirty hours, but seldom more. There were limits on how many people could leave the shelters at once, so there was a scramble for spots on the schedule during this slack time, because at some point in the early afternoon of the daymonth, the onshore wind would begin, a hard flow of air barreling in off the sea into the interior of Greenland, as the land got hotter than the ocean and its air rose and vacated a space that cooler sea air rushed in to fill, the wind arriving in puffs and faltering breezes, then in a steady gentle push, which strengthened through the afternoon of the daymonth until sunset. This was generally the time of strongest onshore winds, although that varied of course, as storm systems swirled around Aurora in the usual fractal nautiloid motions that occur when gases move around the exterior of a rotating sphere. Although Aurora’s day was also its month, it was still rotating once in that daymonth, and that slow rotation caused the air in the atmosphere to drag a little in relation to both hydrosphere and lithosphere, creating winds that curled and mixed to create the usual trades, polar swirls, and so on.

  So: almost always windy. When it wasn’t, they left the shelters and walked around, enjoying the ability to do so without bending over into the gusts, without being thrown to the ground. Even in the dark of the eclipse they enjoyed being out in the still air, the beams from their headlamps lancing and crisscrossing to illuminate their sea valley and its backing cliffs.

  Jochi had his name drawn in the lottery to go down, and he descended in the next group, and as soon as he could, got on the list to go out of Hvalsey town in a suit, and Freya watched with him as he went out and immediately was knocked off his feet by a katabatic gust. Everyone in his group was knocked over but one, and they all cried out in surprise or fear, as did Freya up in the ship. Jochi crawled around for a while, laughing, and got in the lee of the city wall and stood again, still laughing. He danced around in the shelter of the wall as if he were a winter lamb let out of the barn for the first time in spring. He gamboled.

  Euan’s particular pleasure now was to hike a trail he had helped to establish along the south side of the river, exploring the estuary and then the beach between the lagoon and the ocean. The sand on the riverside and down on the beach was of
ten hard-packed, under a loose layer that got lifted in the winds and deposited in miniature dunes that scalloped the packed sand under it. Near the water there were also very fine crosshatchings of sand, sometimes cut by watercourses so that many layers of this weave of layers was revealed. At first they said that Aurora had no tides, being tidally locked to Planet E and thus always tugged by it in the same direction, but now there were some people in the settlement who thought that the combination of Tau Ceti and Planet E might tug a bit harder on Aurora in the direction of Planet E, while when Tau Ceti was on the other side of Aurora, the contrary tugs of Planet E and the star would shift the water covering most of Aurora in ways that could be seen. And there were slight libration tides as well, created when Aurora rocked a little in its facing toward E. Thus there were two kinds of slight tides, both moving at the pace of the daymonth, but in different rhythms. And indeed on the beaches there was often a fine crosshatching that was perhaps evidence of these tides. They had not been able to measure changes in the height of the ocean, however, and so there were others who argued that the crosshatching resulted not from the two little tides, but from the steady inflow of big wave after big wave, each large one leaving a mark across and slightly at an angle to the previous waves. Most of the scientists still on the trip doubted that waves could leave such regular marks; some of them postulated they were sandstone layers exposed to the sea, and the residue of changing sea levels in different eras of Aurora’s history.