Aurora

by Kim Stanley Robinson

“Yes.”

  “Well, good.” Badim regarded her. “That would be good.”

  Preparations continued for their descent. Down to Aurora, down to Greenland, down to their new world, their new day. They were ready. They wanted down.

  3

  IN THE WIND

  And went down in the ships, standing on tongues of fire, down to the west coast of the island they called Greenland. Its tip pointed at Aurora’s north pole, but the shape of the landmass was very like, they said. Actually the match was approximate at best, a .72 isomorphy on the Klein scale. Nevertheless, Greenland it was.

  Its rock was mostly black dolerite, smoothed flat by the ice of an ice age. The ferries carrying people landed near its west coast without incident, close to the robotic landers they had sent down previously.

  In the ship almost everyone gathered in their town squares and watched the landings on big screens, either in silence or raucously; it was different town by town. Whatever the reaction, almost everyone’s attention was fixed on the screens. Soon they would all be down there, except for a rotating maintenance crew that would keep the ship running. Other than those people, everyone was to live on Aurora. This was good, because almost everyone who expressed an opinion said they wanted to go down. Some confessed they were afraid; a few even said they had no interest in going down, that they were content in the ship. Who needed bare rock, on a lifeless moon, on the shore of an empty sea, when they already had this world they had lived in all their lives?

  Some asked this, but most then answered, I do.

  And so they watched the landings on their town screens with an intensity nothing else had ever inspired. Median heart rate, 110 beats a minute. A new world, a new life, a new solar system they intended to inhabit, to terraform and give to all the generations that would follow. Culmination of a voyage that had begun on the savannah more than a hundred thousand years before. New beginning of a new history, new beginning of time itself: Day One, Year Zero. A0.1.

  In ship time, 170.040.

  Freya’s friend Euan was in the first landing crew, and Freya watched for him on the screens, and listened to his feed as he talked his way around the little shelter already there on the surface next to the landed ferries. Everyone in the landing party was transmitting to family, friends, town, biome, ship. Euan’s voice was lower in tone than when he was a boy, but otherwise he sounded just as he had when they were kids in Nova Scotia: excited, knowing. It was as if he expected to see more than anyone else down there. The sound of his voice made Freya smile. She didn’t know how he had gotten into the first crew to go down, but on the other hand, he had been good at getting into things he wanted to get into. Crews had been selected by lottery from among those trained to the various landing and setup jobs, and he had no doubt passed the tests to determine who was competent to the tasks involved. Whether he had rigged the lottery too, she could not be sure. She kept her earbud tuned to his voice-over in particular. All in the landing party were talking to people up in the ship.

  Planet E’s orbit was .55 AU in radius, closer to Tau Ceti than Venus was to Sol, but Tau Ceti emits only 55 percent of the luminosity of Sol, so E and E’s moon were receiving 1.71 times as much stellar radiation as Earth, while Venus receives 1.91 times as much. E’s moon, now called Aurora by everyone, orbited in a tidally locked, nearly circular orbit of E, at an average distance of 286,000 kilometers. E’s mass created a gravity of 3.58 g; Aurora’s was .83 g. This was the main reason they were going to try to occupy Aurora rather than E, which, though it fell in the class called “large Earth,” was too large, or to put it more precisely, had too strong a gravitational pull at the surface, for their rockets to launch off it, let alone for them to feel comfortable or even to survive.

  Aurora received light both directly from Tau Ceti and by way of a powerful reflection of Tau Ceti’s light from the surface of E. This reflected sunlight (taulight?) was significant. Jupiter, for comparison, reflects about 33 percent of the solar radiation that hits it, and E’s albedo was almost as great as Jupiter’s. The sunlit part of E was therefore quite bright in Aurora’s sky, whether seen by day or night.

  The surface of Aurora therefore experienced a complicated pattern of illumination. And because it was tidally locked to E, as Luna is to Earth, the pattern was different for the E-facing hemisphere and the hemisphere always facing away from E.

  The hemisphere facing away from E had a simple pattern: its days and nights lasted nine days each, the day always full sunlight, the night fully dark, being starlit only; and never a sighting of E at all.

  The hemisphere facing E had a more complicated pattern: its nine-day-long solar night included a very considerable amount of reflected sunlight from E, which always hung in the same spot in the sky, different spots from different parts of Aurora, but always fixed, while going through its phases. Nights on the E-facing hemisphere of Aurora saw E go from quarter phase (circle half illuminated) to full moon around midnight, waning to quarter phase again near dawn. Thus there was always significant E light during this side of Aurora’s solar night. The darkest time in this hemisphere actually came at noon during its solar day, when E eclipsed Tau Ceti, so there was neither taulight nor E light on the part of Aurora that was eclipsed, which was a very broad band across the middle latitudes.

  There were also narrow libration lunes at the border of the two hemispheres of Aurora, in which E, while it went through its phases, rose and dipped just above or below the horizon. This libration rocking happened everywhere of course, but it was not so easy to see when it was high in the sky against the always shifting background of stars.

  Possibly a diagram would make this regime clearer, but the analogy of Luna to Earth may help to make things comprehensible, as long as it is kept in mind that from Aurora, E seemed much larger in the sky, bulking about ten times larger than Earth seen from Luna; and because its albedo was high and it received 1.71 of Earth’s insolation, it was much brighter as well. Big, bright, and from wherever one stood on the E-facing hemisphere of Aurora, always fixed in the same spot in the sky, granting a slight libration shift. At their landing site, this spot was almost directly overhead, only a bit south and east of the zenith: a big glowing ball of a planet, waxing and waning slowly. “When we learn the phases, we’ll be able to use it like a clock,” Euan said to Freya. “A clock or a calendar, I don’t know which to call it. The day and the month are the same thing here. Whatever we end up calling it, it’s not a unit of time we had on the ship.”

  “Yes we did,” Freya said to him. “Women’s periods. We brought the months with us.”

  “Ah yes, I guess we did. Well, now they’re back in the sky again. But only eighteen days long. Wonder if that’s going to mess things up.”

  “We’ll find out.”

  They had chosen to land on Greenland partly because it was in the hemisphere facing E. Someone said that if one were standing on E looking up at Aurora, Greenland would have been located on the disk of Aurora about where a tear would leave the left eye of the man in the moon, on Luna as seen from Earth. A nice analogy.

  The complicated regime of light on Aurora created very strong winds in its atmosphere, and the waves on its ocean surface were therefore often very large too. These waves had a very long fetch, indeed in some latitudes they never encountered land at all, but ran around the world without obstruction, and always under the pull of .83 g, so that they often reached a very large amplitude, well over 100 meters trough to crest, with the crests a kilometer apart. These waves were bigger than any that ever occurred on Earth, except in tsunamis. And since they never went away, during the nine-day nights the ocean surface froze over only in certain bays, and in the lee of various islands. When the time came for people on Aurora to take to the ocean, a time many spoke of enthusiastically, the seafaring would involve considerable challenges.

  “So, now we’re about to go outside the station,” Euan said into his helmet speaker. Within the ship, 287 people were listening to his feed, while 1,814 peopl
e listened to other members of the landing expedition now leaving the station. 170.043, A0.3.

  “Suited up, the suits are pretty flexible and light. Good heads-up display in the faceplate, and the helmet’s a clear bubble, at least all of it I can see, so it feels fine to have it on. The g feels just like on the ship, and the air outside is clear. Looks like it might be windy, although I don’t know why I say that. I guess I’m hearing it pass over the station buildings, maybe the rocks too. We’re far enough from the sea that it isn’t visible from here, but I hope we’ll be taking the car west until we get to the bay west of here and can have a look at the ocean. Andree, are you ready to go? All right, we’re all ready.”

  Six of them were going out, to check on the robotic landers and the vehicles that were ready to drive. If the cars were good, they would take a drive west to the coast, five kilometers away.

  “Ha-ha,” Euan said.

  Freya settled down to listen to him and watch the view from his helmet cam.

  “Now we’re outside, on the surface. Feels the same as in the ship, to tell the truth. Wow, the light is bright!”

  He looked up, and the camera view of the sky flared with Tau Ceti’s light, then reduced it with filters and polarization to a round brilliance, big in the royal blue sky—

  “Oh wow, I looked at it too long, I’ve got an afterimage, it’s red, or red and green both at once, swimming around. Hope I didn’t hurt my retinas there! I won’t do that again. I thought the faceplate would do better at filtering. It’s going away a little. Good. All right, lesson learned. Don’t look at the sun. Better to look at E, wow. What a giant round thing in the sky. Right now the lit part is a thick crescent, although I can see the dark side of it perfectly well too, I wonder if that comes through in the camera. I can see cloud patterns too, just as easy as can be. It looks like a big front is covering most of the dark part, sweeping into the part that’s lit. I’ve got a double shadow under me, although the shadow cast by E light is pretty dim—

  “Wow, that was really a gust! It’s very windy. There’s nothing to show it here, the rocks are just sitting there, and I’m not seeing any dust blowing. The horizon is a long way off.”

  He turned in a circle, and his audience saw flat ground in every direction. Bare black rock with a reddish tint, striated with shallowly etched lines. Like the burren, someone said, a part of Ireland where an ice cap had slid over flat rock and stripped anything loose away, leaving long, narrow troughs that crisscrossed the rock.

  “It’s never this windy on the ship. Do these suits gauge wind speeds? Yes. Sixty-six kilometers an hour, it says. Wow. It’s enough to feel like you’re getting shoved by an invisible person. Kind of a rude person at that.”

  He laughed. The others with him started laughing too, falling into each other, holding on to each other. Aside from their shenanigans, there were no visible signs of the wind. Cirrus clouds marked the sky, which was either a royal blue or a dark violet. The cirrus clouds seemed to hold steady in place, despite the wind. Atmospheric pressure at the surface was 736 millibars, so approximately equivalent to around 2,000 meters above sea level on Earth, though here they were only 34.6 meters above Aurora’s sea level. The wind was stronger than any they had experienced in the ship by at least 20 kilometers per hour.

  The surface vehicle they had had charged batteries as expected, so they climbed into it and rolled off west. The light from Tau Ceti blazed off the rock ahead of them. From time to time they had to make a detour around shallow troughs (grabens?), but by and large their route was straightforwardly westward, as most of the troughs also ran east and west. Their helmet-camera views jounced only a little from time to time, as their vehicle had shock absorbers. The explorers laughed at the occasionally bumpy ride. There was nothing like this on the ship either.

  Maybe there was nothing on the ship that was quite like what they were experiencing now. As a gestalt experience it had to be new. The horizon from their vantage point, about three meters above the ground, was many kilometers off; it was hard for them to say how many, but they guessed about ten kilometers away, much the same as it would have been on Earth, which made sense. Aurora’s diameter was 102 percent Earth’s; its gravity was only .83 g because Aurora was less dense than Earth.

  “Ah look at that!” Euan cried out, and everyone else in the car exclaimed something also.

  They had come within sight of Aurora’s ocean. Lying to the west in the late afternoon light, it looked like an immense bronze plate, lined by waves that were black by contrast. By the time they reached a short cliff over the sea’s edge, the plate of ocean had shifted in color from wrinkled bronze to a silver-and-cobalt mesh, and the lines of waves were visibly white-capped by a fierce onshore wind. They exclaimed at the scene, their cacophony impossible to understand. Euan himself kept saying, “Oh my. Oh my. Will you look at that. Will you look at that.” Even in the ship many people cried out in amazement.

  The explorers got out of the car and wandered the cliff’s edge. Fortunately, when the wind caught them and threw them off balance, it was always inland and away from the cliff.

  The cliff’s edge was about twenty meters above the ocean. Offshore, waves broke to white crashing walls, which came rolling in with a low roar that could be heard through the explorers’ helmets, always there under the keening of the wind over the rocks. The waves crashed into the black cliff below them, flinging spray up into the air, after which masses of white water surged back out to sea. The wind dashed most of the spray into the rocks of the cliff, although a thick variable mist also rose over the cliff’s edge and was immediately thrown over them to the east.

  The explorers staggered around in the wind, which was now so very visible because of the flying spray and the ocean’s torn surface. Wave after wave broke offshore and was flatted to white as it rolled in, leaving trails of foam behind each broken white wall. The backwash from the cliffs headed back out in arcs that ran into the incoming breakers; when they crashed together, great plumes of spray were tossed up into the wind, to be thrown again in toward the land. It was a big and complex view, brilliantly lit, violently moving, and, as everyone could hear by way of the microphones on the explorers’ helmets, extremely loud. Here at this moment, Aurora roared, howled, boomed, shrieked, whistled.

  One of the explorers was bowled over, crawled around, got onto hands and knees, then stood up, carefully balancing, facing into the wind and stepping back quickly four or five times, swinging arms, ducking forward to hold position. They were all laughing.

  It was a question what they would be able to do on such a windy world, Freya remarked to Badim, if it stayed that windy all the time. She added that it was more the ghost of Devi worrying in her than she herself. She herself wanted to get down there as soon as possible and feel that wind.

  Meanwhile, down on Aurora, they were getting the construction robots started in their various tasks. A very slow sunset gave way to a night illuminated by the waxing light of E, always overhead. E’s light diffused to a glow in the air somewhat like a faint white mist, which the settlers found they could see well in. The sky did not go black but rather stayed a lambent indigo, and only a few stars were visible.

  The dolerite of Greenland was obdurate and uniform, containing not much in the way of other more useful minerals. They would have to hunt for those, but in the meantime, it was dolerite they had to work with. Many construction vehicles grumbled around cutting blocks of dolerite from the side of grabens, and stacking them in a wind wall to shield their little collection of landers. There was an almost continuous whine of diamond-edged circular saws. Meanwhile a smelter was extracting aluminum from crushed dolerite, which in this area proved to be about half a percent aluminum in composition. Other robotic factories were sheeting this extracted aluminum for roofs, rodding it for beams, and so on. A few of the robot excavators were set to drilling in a graben with a gravitational bolide under it, in the hope of locating some iron ore to mine. But for the most part, until they found some area
s of different mineral composition, they were going to have to work with aluminum as their metal.

  Aurora had a good magnetic field, ranging from .2 to .6 gauss, and that plus its atmosphere was enough to protect the settlers from Tau Ceti’s UV radiation. So the surface was well protected in that regard, and really the moon’s surface was quite a benign environment for humans, except for the wind. Every day explorers came in from their trips exclaiming at the force of the gusts, and one of them, Khenbish, came in with a broken arm after a fall.

  “People are beginning to hate this wind,” Euan remarked to Freya during one of their personal calls. “It’s not horrible or anything, but it is tedious.”

  “Are people scared of it?” Freya asked him. “Because it looks scary.”

  “Scared of Aurora? Oh hell no. Hell no. I mean, it’s kicking our butts a little, but no one comes back in scared.”

  “No one going to go crazy and come back up here and beat people up?”

  “No!” Euan laughed. “No one is going to want to go back up there. It’s too interesting. You all need to get down here!”

  “We want to! I want to!”

  “Well, the new quarters are almost ready. You’re going to love it. The wind is just part of it. I like it, myself.”

  But for many of the others it was the hard part; that was becoming clear.

  A slow sunrise brought dawn on Aurora, and just over four of their clock days later, the high noon of their month came. During this time the lit crescent of E had shrunk to a brilliant sliver, up there in the royal blue daytime sky, and the blazing disk of Tau Ceti had been closing on that lit side of E as it rose. A time came when the star was too close to E for them to be able to look at either one without strong filters to protect their eyes.