Across the Sea of Suns

by Gregory Benford

  TWO

  “What do you think Ted really means?” Nikka said.

  They strolled along a path that wrapped all the way around the inside of the dome. The best part was a hundred-meter patch of forest, dense with pines and oaks and leafy bushes. It may have been his imagination, but the air seemed better there, less stale.

  “Probably no more than he says. For now.”

  “Do you think they’ll do the same to me?”

  A fine mist drifted over the treetops, obscuring the fields which hung directly over their heads. In the distance, along the axis, Nigel could make out the other side of the dome. Cottonball clouds accumulated along the zero-g axis of the dome, and through them he could see a distant green carpet, so far away only the Euclidean scratches of the planting rows were apparent: a garden zone.

  “He said nothing about it.” Nigel turned to her, spreading his hands. “And at any rate, whatever for?”

  “Next to you, I’m the oldest crew member.”

  “But, blast it!—you’re not old.”

  “Nigel, we’re two decades ahead of anybody else in the crew.”

  He shrugged. “My work requires motor skills. And they’re dead right, I’m getting stiff and awkward. But you’re a general handy type. There’s no—”

  “Your years in the Slowslots retarded all that.”

  “Some. Not a lot.”

  Nikka walked faster, her vexed energy coming out in a particular irked way she had of swinging her hips into her stride. She was still in marvelous condition, he thought. Her straight black hair was drawn back in a Spartan sheath above her lidded, open face. It joined a natural cascade at the crown, to become a jaunty black torrent down half her back. Nigel forced himself to look at her as though she were a stranger, trying for Ted’s perspective. With age her skin had stretched tight over her high cheekbones. She didn’t have her full strength any longer, granted, or the gloss of early middle age she’d once had. But she was a fine, slim edifice that showed no signs of sinking squat and Earthward.

  She breathed in the air with obvious relish. It was better here, near the plants and algae vats. If you closed your eyes you could very nearly think you were in a genuine forest. You could blot out the muted bass rumble of the unending fusion flame.

  “Nigel, it seems so long,” she said suddenly, plaintively.

  He nodded. Twelve years since Lancer fired its drop-away accelerators and boosted achingly up to light speed. He took her hand and squeezed. They had all passed the vast tracts of time with their work, with study, with experiments like the Slowslots, with astronomical observations. But the years had weight and presence.

  Lancer was a rush job.

  In 2041 a giant radio net, laced across the far side of the Moon, picked up an odd signal. It was a weak, shifting pattern, amplitude-modulated. It came in sharp at 120 megahertz, smack in the middle of the commercial radio band. Originally, the farside radio grid had been strung to carry out astrophysical studies in the low-frequency range, down to the 10 kilohertz region. The designers at Goldstone, Bonn and Beijing had only recently installed gear to take the system up into the megahertz range, because the jammed commercial bands were so noisy now that sensitive astrophysical work was impossible from Earth’s surface. The Moon made an effective shield.

  The emission pattern had, as the jargon went, significant nonrandom elements. Patterns would rise out of the galactic background radio noise and then, before the sequence of amplitude modulations could form a coherent pattern, the dim electromagnetic tremor faded.

  The most likely explanation was some intermittent natural process, perhaps resembling Jupiter’s decametric sputtering. That radiation came from electron swarms in Jupiter’s magnetic belts. Waves passing through the belts made the electrons bunch together, so that they radiated like a natural antenna. Jupiter’s emissions had wavelengths hundreds of meters long, well below the megahertz range. To explain these new emissions, astronomers invoked a gas giant planet with much stronger magnetic fields, or higher electron densities.

  When they pinpointed the source, this model made sense. It was BD +36°2147, a dim red star 8.1 light-years away, and it seemed to have a large planet. This was somewhat embarrassing.

  The funding agency, ISA, wondered why a star that close had not been checked routinely for unusual emissions. An obvious explanation was that the action and the grants were in high-energy, spectacular objects—pulsars, quasars, radio jets. Also, the small, red stars were boring. They were hard to see and they led dull lives. BD +36°2147 had never been named. The scramble of letters and numbers simply meant that the star had appeared first in the Bonner Durchmeisterung catalog in the nineteenth century. The declination angle was +36 degrees and 2147 was a serial number in the catalog, related to the star’s other coordinate, Right Ascension,

  From the star’s slight wobble, one could deduce that something large and dark was revolving around it. That was a perfectly logical candidate for the superJovian. Orbital optical telescopes had by this time found hundreds of dark companions around nearby stars, proving that planetary systems were fairly common, and ending a centuries-old argument.

  The first unsettling fact came to light when ISA poked around in the old survey reports from Earth-based radio telescopes. It turned out that BD +36°2147 had been observed, repeatedly. There had been no detectable emission. The present radio waves must have started sometime in the last three years.

  The second surprise came along a few months later. For one rare two-minute interval, a strong wave pattern got through. The amplitude-modulated signal was a carrier wave, just like commercial AM radio. Filtered and speeded up and fed to an audio output, it quite clearly said the word “and.” Nothing more. A week later, another three minute portion said “Nile.” The big radio ear was now cupped continuously at BD +36°2147. Seven months later it picked up “after.”

  The words came through with aching slowness. Some radio astronomers argued that this might be an odd way of cost cutting. As the signal faded in and out, a listener missing a piece of a long sound could still recognize the word. But this theory did not explain why the signal blurred and shifted so frustratingly. It was as though the distant station started transmitting one word and then changed to another before the first was finished.

  The signals continued, occasionally coughing forth a fragment, a word, a syllable—but never enough for a clear message. Still, they had to be artificial. That killed the super Jovian magnetosphere theory. They kept to a fairly sharp frequency, though, and this proved useful.

  Eight months of careful observations picked up a Doppler shift in the frequency. The shift repeated every twenty-nine days. The logical explanation was that the scattered pulses came from a planet, and that planet moved alternately toward and away from Earth as it orbited the red dwarf star. Optical observations fixed the star’s luminosity, and reliable theory then could give the star’s probable mass. It was 0.32 solar masses, an M2 star. Given the twenty-nine-day “year” of the planet, and the dwarf’s mass, Newton’s laws said the planet was nine times closer to its cool star than Earth was to the sun.

  That was as far as observations from near-Earth could go. The radio teams spent years trying to see a Doppler shift from the revolution of the planet itself. It wasn’t there, but nobody expected it to be. A planet that close to its star would be locked with one face eternally sunward, due to the tidal tug between them. Earth’s Moon and the Galilean satellites of Jupiter were tide-locked to their planets, after all. Mercury would be locked toward the sun, but for the competing pull from the other planets.

  But tide-locked worlds were deadly. Everybody knew that. One side would be seared and the other frozen. Who could survive such a place and erect a radio transmitter? Did they only live in the twilight band?

  The only way to find out was to go and see. In 2029, ISA launched small relativistic probes on near-recon missions to BD +36°2147. One failed in a burst of gamma rays 136 light-years from Earth. The inboard diagnostics to
ld a lot about the flare-up in the fusion burn, before the ship disintegrated. ISA adjusted the burn in the second probe and it survived, to dive past the BD +36°2147 system at 0.99 light speed.

  It spotted a gas giant in the right place to cause the star’s wobble, as seen from Earth. But the radio mumble came from an Earth-sized world nearer the star. The probe had been programmed to pass near the gas giant, since its orbit could be deduced from BD +36°2147’s slight rhythm. The other planet was exactly on the other side of the red dwarf star when the probe shot through, so the automatic devices, in a mad scramble to readjust, did not get much data.

  Small, fast probes were cheap. The International Space Agency favored them. But they couldn’t respond flexibly, and game theory proved they were a bad strategic choice, in the face of unknown risks.

  The best posture, the conflict metricians calculated, was reconnaissance in force: Lancer. So the three superpowers used their muscle and appropriated the just-finished Libration Colony project. ISA took the life zone inside the spinning asteroid world, tunneled more rooms in the rock, and added duralith thrust chambers that could bottle a fusion burn. The design was a copy of the Mare Marginis wreck and it worked well. They stirred the soils, planted crops, burrowed hallways, sliced rock, and fine-tuned a miniature ecology inside the hollowed-out ellipsoidal dome.

  All this, to fly at velocities a hairline below light. Toward the red beacon of BD +36°2147, now renamed Ra. The word “Nile” in the transmission, while seemingly irrelevant and possibly a mistake—the error bars in the decoding were significant—became a pretext for invoking Egyptian mythology. The transmitting world was named Isis for the goddess of fertility. The outer gas giant was named for her son, Horus. The astronomical community took two years to decide all this, there were letters discussing the matter in the London Times. The engineers, of course, didn’t give a damn.

  As they walked on through the fields grain rustled, and the dry rasping was like Kansas on a ripe fall day. Nigel shielded his eyes against the hard glare of the phosphors. The huge squares were regularly spaced in the curving floor of the dome, illuminating the fields on the opposite side, powering the ecology of Lancer. Wraparound lighting. The fusion burn in Lancer’s throat gave ample electricity for the phosphor panels, but to Nigel it still seemed like a wasteful squandering of photons.

  Nikka interrupted his thoughts with, “What do you think is our best tactic?”

  “Um?”

  “We have to keep down criticism of us. Of our …”

  “Decaying physical abilities.”

  “Yes.”

  “Right, then—we should work in modest jobs. Low profile.”

  “Until we reach Isis.”

  “Then—well, we maneuver ourselves into interesting work.”

  “Don’t let them argue us into a desk job.”

  “Right. Maybe we’ll have to be content with merely controlling robots or something, but—”

  “No paper pushing.”

  “Just so. Meanwhile—”

  “Stave off the bastards.”

  She smiled and repeated with some relish, “Stave off the bastards.”

  Months before, Lancer had dropped a self-constructing radio net, letting it tumble away in the wake. Riding inside a cocoon of shock-ionized plasma, they could not make high-resolution radio maps.

  The net uncurled and deployed. Alex controlled the servo’d antennas by remote, painstakingly assembling aperture synthesis maps of the Ra system. The star itself flared violently, sending tongues high into its corona. Detailed mapping of their target, Isis, took much longer.

  Nikka prodded Nigel awake when their apartment Sec chimed. “Let me be,” he growled.

  “Stop doing your croc-in-the-sun impersonation. It’s the Assembly review of the first Isis map. You wanted to see it.”

  “Ah. I’d fancy that.”

  Nikka tapped her wrist and the wall screen clicked on. She silenced Alex’s voice-over explanations and enlarged the map. Nigel peered at the round image. The Isis disk was a spaghetti scramble of contour lines.

  “Planetary acne,” he said.

  Nikka said, “Looks like a river valley system, there.”

  “Couldn’t be. Trick of the eye, probably. This isn’t radar, remember. They’re picking up the Isis transmissions.”

  “How can it come from all over the planet’?”

  He squinted. “It can’t. The simple, efficient way to send across interstellar distances is with one fixed antenna.”

  “Yes …” She combed back her sleek black hair with her fingers. “Or so we think.”

  “Electromagnetic waves are culture-independent. Makes no sense to use lots of antennas.”

  He tapped into the interactive-mode discussion, still lying in bed. No interesting ideas surfaced. “Wait’ll we’re closer,” he said.

  Nikka dialed the map to max scale. “I still say it looks like a river valley.”

  THREE

  Isis was a red world. Mars-tinged, Nigel thought, staring down at it. But rich with air, cloud-choked.

  One warm face forever pinned toward Ra, the other staring blank and frozen into the eternal cold: tide-locked. In the immemorial night the land groaned beneath vast blue glaciers. Half a planet, capped in ice.

  Winds from the twilight fed the great, slumbering, white-crusted mountains, bringing breaths of fresh moisture. At the eternal dawn line where dim pink light licked, icebergs calved into a red ocean. The sea circled Isis, pole to pole, separating ice and land. It was pink and glinting, scratched by winds, dotted with orange-yellow clouds.

  More sunward still, broad fans of waves battered at the base of steep, flinty chasms. The sea clawed at the rising ramparts of the one vast stained brown continent.

  Fingers of water thrust inland, toward Ra. River valleys carved the gray granite, as if clutching the world’s face, to force it toward the fire. Fingers: poking at the Eye.

  Channel #11: “Yeah, that pattern, what’d I say, fits the theory. Perfect stress pattern there, you can see the normal faulting and graben at the poles—”

  Channel #20: “Jess a sec, theh ah no poles at all, an’. if unnerstan your calc, your equilibrium is wrong from step one—”

  Channel #5: “—Jeezus, check the chem inventory down there, I’d—”

  Channel #11: “No, I’ve got a whole continuum of theoretical equilibria I can use and this case fits in; it all works if we assume Isis formed rotating, with a bulge at the equator, and then when Ra spun it down that released the centrifugal energy, so Isis tried to readjust its surface to get rid of that pot belly, and you get fracturing in a global pattern—”

  Channel #5: “—too much absorption in those oceans, an’ some odd lines, lookit those spikes around 5480 angstroms, that’s not—”

  Channel #18: “Funny, the lakes in those highlands, partway out from the Eye, they’re blue, but the ocean is pink. I guess whatever—”

  Channel #5: “That’s fresh rainfall up there in the mountain passes, melted snow, it should look blue—”

  Channel #11: “—that leaves the equator free, see, so thrust faults split the dome pattern, and the energy got released toward the rim—”

  Channel #20: “Okay, no poles, your calc stipped a bound’ry layer an’ thahs what makes the calc work out. Those headwalls in the rim gouge pattern, see ’at? I guess they prove some kinda big crust relaxation when it slowed down, started a whole big tectonic process—

  Channel #5: “—the 5480 structure is just backscatter from the hills, must be, Nigel, ’cause that’s the iron silicate group clear as day, damn muddy day down there though, an’—”

  Channel #11: “—you get these compression networks that give those wrench faults, or lateral faults, I can see them on this IR blowup, here, lots of rifting, a whole morphology set up when the planet spun down—”

  Channel #3: “—but then what’re those ghastly spikes dead center of the polarization pattern, eh? You’re surely not going to ask me to believe a mud
flat is giving us those spikes, are you? Scarcely. The sea is giving us those, and it has to have iron oxides to do that and give sufficient line strength—

  Channel #18: “Blue lakes means that whatever makes the seas red doesn’t operate at high altitudes—”

  Channel #5: “That’s garbage, there can’t be a height effect with that kind of gentle gradient, it just won’t support a—”

  Channel #18: “Okay, then it takes time to make the chemistry go, so by the time the rainfall has run down to the lowlands something’s—”

  Channel #29: “—he’d got that wrong twice, Christ, so I kinda shrug and mutter, nothing wrong with having nothing to say, sure but try not to say it out loud, and the sonabitch went straight to Gulvinch about it then—”

  Channel #20: “— intensifahs all ’at till the domed strata—yeah, ’at’s the ticket—they can’t support the shear stress an’ they rupture, all back unner that ice on the other hemisphere too I bet, uh-huh, an’ you get lotsa cyclin’ in the surface materials, rip open the seams ever’ couple hunnert thousan’ years, think what that does to the rep rate with the atmosphere when you bake out that iron exposed fresh ever’ time—”

  Channel #5: “Look, that’s one thing we do know: look at that spectrum, it would be a reducing atmosphere with all that iron, for sure, except the oxygen levels get pumped up, but even so it’s only around the two percent level, two percent 02, you can see that right here, look, it’s just a spike out on that wing, the line strengths are wrong, nothing like Earth, but I bet it’s the same damn process, the same way our air converted over from reducing billions of years back, trouble is it’s not much O2 is it? Not damn much if you want to breathe down there.”

  Channel #6: “It’s both forms, open your eyes, lay that one over the other and it jumps right out at you—”

  Channel #3: “Ah, ferrous and ferric. Both. So there’s a lot of oxygen down there, as much as Earth, but it’s tied up in the iron.”

  Channel #29: “—nothing I could say would—”