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—”

Channel #20: “—so see this fits what the backscatter boys say, the faultin’ rips up the goddamn turf so much the iron gets reprocessed alla time an’ the air, it jess can’t hold onto its oxygen, the water jess runs off ever’ time it rains an’ the sea, it’s jess this solution a ferrous crap, ’at’s where th’ O₂ is, man I tell you—”

Channel #56: “That jocko over in P4 has got some crazy idea, lissen to him, thinks it’s all iron, but give a gear at this, in the big spot there, see that big volcano, that’s sulfur for sure, big spouts of it coming out reg’lar as Maybelle, sulfur volcanoes smack in the middle of the Eye, and if that doesn’t tie up a lot of oxy, with those winds, I mean, we measured gusting velocity from the action-frame zats and they’ll mix the whole damn atmosphere in two, maybe three years, so you’ve got sulfur oxide all down there, that’s what the Eye is, that’s not sand dunes, not silicon dioxide, it’s sulfur dioxide—”

The picture sharpened as computers edited out random refractions from the clotted air below. Isis swam nearer.

Yellow. A dry, ancient yellow. Smooth sands of it, shimmering, flecked with tan ridges of weathered rock. The Eye peered at Ra, which hung forever directly overhead. Out from the hard-baked center, the subsolar point, swept winds heavy with pungent acid dust. Dunes marched before the winds in ranks a hundred kilometers long. Slowly they swerved as the air currents circled, following a trade-wind pattern, returning to the blistered pupil of the Eye, surging in a timeless cycle.

The Eye’s edge faded into russet, then into brown. A hint of moisture; scrub desert. Rumpled red hills built into a concentric ring of mountains: socket of the Eye. Snow dotted the peaks white. High valleys cupped cold air over the steel-blue sheen of lakes.

The steady rub of the Eye winds had smoothed the land. The breeze stirred up pink dust, thick sheets that poured over the high mountain slopes and down, out-ward from the Eye, filling the valleys with a roiling haze. Only in the shifting spots where neither clods nor dust lay upon the land could the distant telescopes see the dry plains and carved valleys of Isis.

The single, immense, concentric mountain range was intricate and fault cut. Muddy rivers ran down the broad slopes, away from the Eye, toward the planet-circling sea. Farther from the Eye, scrub desert yielded to matted vegetation. Brown grass. Something like trees. Shades of brown, of pinks and grays and pale orange.

A fine dust hung in the lower air, fuzzing optical images, stealing definition. Only in the infrared was the seeing good enough to distinguish objects in the five-meter scale range. Large flora. Bands of vegetation crowding the snaking rivers.

The IR peered down and picked out detail. Dark beds of plant life in the sea. Grasslands. And then, movement.

“ReppleDex, this is Command. You guys got that system up yet, or do we kick ass out there?”

We got good definition in the radio right now, Ted. Give it a—

“I’m looking at it, Alex. What we want is the interferometry—”

“They’re point sources, aren’t they?”

“Nigel, this is Ted. Get off the comm lines.”

“I’m a consultant, remember? Just eavesdropping, anyway.”

“Okay, so long as you don’t get in the way of—Hey, RD, when can we have—”

He’s right, Ted, we still can’t resolve the sources. They’re damned small. Any really big dish we could see at a range of one AU, so I’d think by now we shoulda picked up—

“Okay, okay, that’s interesting. But—”

—and the reason we’ve never been able to make sense out of the signals, we’ve got that figured now—

“Oh? What?”

There are these point sources, maybe a million of ’em, but they’re not transmitting together. I mean, they’re not in synch phase-locked. All the sources are trying to send the same stuff but they’re all a little behind or a little ahead of each other, so it gets muddied up.

“Beats the hell out of me, why somebody’d pick that way for interstellar communication.”

“Alex, what is the length over which the signals are correlated?”

“Nigel, I asked you—”

“Leave off a bit, eh? Alex?”

Well, lemme run this here … Yeah, the spatial correlation length is about thirty klicks, maybe a little more.

“How does it fit in with the topography?”

Here, plug me in on that multichannel, Ted, and—Yeah, there it is.

“Does it follow the valley profiles?”

Uh, yeah. Sort of. Sources are strung out along the valleys. Not many in the mountains.

“The valleys are where the best living is. The water. Over to you, Ted.”

“Many thanks, Nigel. It is nice to get a word in now and then. Let me get this straight, Alex. If you scan the interferometer across the valley, you find the signal is coherent. All the point sources are sending together?”

Correct.

“But if you go to the next valley, the sources are sending something slightly ahead or behind of the first valley?”

Yeah. That’s what’s so goddamn strange. The bit rate is still low, too. And the sources, they’re not steady.

“How so?”

Well, every few minutes one of ’em will drop out. A new one comes in every now and then, too, so the number is about constant.

“Huh. Look, Alex, I called to ask about the outflyer dish. You were going to have it on line by 1400 hours, and that’s come and gone. We need that bigger base line to get the definition we need, and we damn well need it now.”

“Give it a rest, Ted.”

“Nigel, I thought you—”

“Merely kibitzing, if you please. I’m sure Alex will have matters cleared up at his end if you cease ragging him about it. I wanted to take a moment to review all this, Ted. You’ve got the optical and IR profiles right in front of you, I’m sure.”

“Yeah, you can come down here to Command and see them if you want.”

“Already have. I’m sticking to this console, to use the self-programming capabilities. Anyway, Command is crowded.”

“Okay, okay. If you’d wait for the input like the rest of the crew—”

I was wondering if you’d considered the implications, Ted. No trace of cities. No urban areas. No big straight features, no fields or roads. And the EM transmissions are weak, except for that interstellar signal.”

“Yeah. Damn funny. But maybe they’re living underground, using all the land for agriculture, and they use cables for info transfer. Hell, we do that back on Earth. We wasted power on atmospheric transmissions only in the start-up days of radio and TV.”

“Even agriculture has a signature, this close. We could see croplands.”

“Maybe so, maybe so.”

“I’ve been cross-correlating Alex’s prelim fixes on the radio sources—the EM points, he calls ’em for electromagnetic—with the IR. Anyone in Command done that?”

“Uh, I don’t—”

“I’d like to check my work. There are signal-to-noise problems and I’ve been using the self-programming subsystems to unfold it—”

“No, look, Nigel, we’ve been too busy to try all that yet. I’d suggest—”

“Point is, some of the EM points and the IR points are the same.”

“Which ones?”

“There’s the rub. It’s the moving IR sources, looks like.”

“The ones we got variable fixes on? I don’t under—”

“What I’m saying, Ted, is that the radio transmitters give off heat as well. And most important, they’re moving.”

“Well, I don’t—”

Hey we’ve got this whole rig up, but you guys got to keep aligned with us or we’ll have shit to show for it when—