"But you're just a c.o.c.k-eyed optimist."

She didn't answer, but picked up her pen, once more, tapped at the sequence of numbers she'd written across the top of the page. "Spatial coordinates? A location?"

"It's not longitude and lat.i.tude. At least not by any system I know."

She shook her head. "I guess we should just send a command sequence. Let's ask her to ping us."

They did just that, and roughly twenty-seven hours later, there was a pause in her broadcast. But then, instead of giving the programmed response to the command sequence, she simply began sending her original sequence of numbers again. Shortly thereafter, both follow-up detection locations called to verify the "hit," and confirmed location and range. The contact could only be Pioneer 10.

Kurt Costigyan sat in silence for a moment after Santiago delivered the news, then grinned and said, "Cool. I'm going to call a press conference. Contact NASA and let them know it's official-the prodigal has phoned home."

NASA was delighted; the press, full of questions, mostly unanswerable: Why was Pioneer signaling now, after such a long silence? What had prompted it? What did the signals mean? Why didn't she respond to their command sequences?

That at least, Kurt thought, was fairly easy to explain. "Chances are," he told the flock of science reporters, "the receiver is damaged."

"Does that mean you won't try contacting her any more?"

"Not at all. We'll certainly keep trying. It's also possible that her signal processor is malfunctioning. The sequence we sent may not raise her, but another one might."

While bits of their press conference played in living rooms across the US and Canada, Team Quetzalcoatl pondered their next message to Pioneer 10. It was Kurt Costigyan who came up with the winning entry.

"Why don't we echo the sequence she's sending back at her?"

"Doesn't it make more sense to send a standard message?" Santiago argued.

The project liaison, Dr. Peter Grace, who had arrived that morning from NASA, was quick to agree. "It makes a lot more sense. Sending a message she won't even recognize is just a waste of project time and money."

"We've already sent a standard command sequence and were roundly ignored," said Kurt. "I'd like to try something different."

"Why not compromise?" suggested Gita. She sat so far forward in her chair, Santiago was afraid she was going to fall out of it. "Send a standard sequence followed by the echo. Or vice versa."

"Look," said Grace, "Pioneer is still a NASA s.p.a.cecraft. You guys drew the job of monitoring her, but I think in this department, NASA should call the shots. Send a command to run a diagnostic and report status."

"It's our processor time, dammit! If we want to send a recipe for Masoor Dal we should be able to send it."

Kurt let out a crack of laughter. "Good Lord, Gita! Save some energy for the House Budget Committee."

"Yeah," said Kev, eavesdropping from where he huddled in a tangle of wires behind one of the equipment racks, replacing a bad cable. "Besides, if you sent Masoor Dal to ET, you'd start an interstellar war. They'd think it was a biological weapon."

"Just because you can't handle Indian food-" Gita began, but Kevin popped out from under the console waving the faulty cable.

"You're ready to rock, boss," he told Santiago.

Santiago glanced at Kurt. "What are we sending?"

Kurt shrugged. "Standard command sequence requesting a diagnostic and status. If that doesn't work, we'll take it from there."

"Meaning we'll send the echo?" asked Gita.

"Meaning we'll cross that bridge when we come to it."

They sent the request for status exactly as stipulated. During the wait for Pioneer's response, they fielded several emails from their loyal Quetzalcoatl devotees offering all manner of explanations for the message Pioneer had sent. The most interesting ones encouraged them to work the numbers out as dimensions. But while it was true the repeated figure could form a square 27.44 inches, feet, meters or whatever on a side, the other figures seemed to bear no relation to each other.

The window of probability exhausted itself on a Sunday afternoon. Pioneer stopped transmitting for a period of five minutes, suggesting that she had received the command sequence and was processing it. Then she began transmitting again-the same eight numbers in the same order.

At that point, Drs. Rodriguez and Mukerjee, finding themselves alone with a t.i.tanic radio telescope and 75 gigaflops of computational horsepower, decided to queue a message of their own to Pioneer 10 so that if, by some chance it were approved, they'd be ready to send it.

Santiago was keying in the message when their Program Director strolled into the lab. Gita jumped guiltily and straightened from where she had been peering over her colleague's shoulder.

"My, but you two look like a couple of cats caught sizing up the canary," observed Kurt. "What's up?"

The two exchanged glances, then Santiago said, "We just wanted to be ready in case Dr. Grace let us send another sequence."

"Dr. Grace will not be back until Tuesday. He had a pressing matter to attend to at Kennedy s.p.a.ce Center."

Gita's face fell. "You mean we have to wait until Tuesday to try again? Kurt, that's a waste of time! We should send now."

Kurt's eyebrows rose in an exaggerated arc. "Who said we had to wait? As I recall, the transmission schedule is the Program Director's purview. I a.s.sume you've queued the echo?"

Santiago nodded.

"Well, then why don't you just ask the Program Director if you can send it?"

Drs. Rodriguez and Mukerjee exchanged glances, and Dr. Rodriguez asked. "Dr. Costigyan, is it your opinion that we should echo the Pioneer's last message?"

"Make it so."

Santiago hit SEND, confirmed, then sat back in his chair. "Well, there it goes. Now we wait."

"You did what?" Dr. Grace was incredulous.

Kurt looked up at him from behind his desk. "I said: We sent the echo."

"It's a waste of time, Kurt."

"I happen to disagree. We're still scanning other areas. The only time it took was Sandy's time queuing the sequence."

"Sandy?"

"Dr. Rodriguez. Of course, Dr. Mukerjee was in attendance, so I suppose you'd want to argue that she wasted her time, too."

Grace shrugged and dropped into the chair across the desk. "It's your staff, doctor. If you don't mind them pursuing wild geese-"

"Excuse me-Dr. Costigyan?" Roz Klein stood in the door of his office, her face flushed. "Pioneer is responding."

The lab was as quiet and tense as a hospital waiting room. Quetzalcoatl staffers-techs, engineers, software experts, and the science crew-had come out of the woodwork to attend, every one of them trying to peer over Santiago Rodriguez's shoulder at his screen.

"What do we have?" Kurt asked, pushing through a cl.u.s.ter of techs.

Santiago glanced up and Gita vacated her chair to allow Kurt to take her place.

"She paused, as usual. This time for exactly three minutes, fifteen seconds. Then she resent the original sequence. We thought, okay, that's it, she's just . . . " He glanced at Gita. " . . . just dreaming."

"Dreaming?" repeated Dr. Grace.

Gita flushed. "Spinning off old data. Reliving old broadcasts."

"But then the sequence changed," said Santiago.

"Show me." Kurt rolled his chair closer.

"The pattern is the same," Santiago told him as he shifted the display to show the decoded output of the Multi-Channel Spectrum a.n.a.lyzer. "And the first part of the sequence is the same: 18.9 and 27.44 repeated four times. Then it changes: 103.6, 134.1, 99.1. One digit off from the first sequence. Now, the third sequence-"

"The third sequence?" repeated Kurt.

Santiago nodded. "The third sequence starts out just like the other two-an identical sequence of five numbers. But this time the last three numbers are: 108.2, 121.9, 107.6."

"Completely different," observed Grace.

"But the seventh number is the same as in the first sequence," said Kurt. "That could be significant."

Grace shrugged. "And it could be mere chance."

"But look at the first set of five numbers," said Santiago. "It's the same for all each set. That's hardly random."

Grace shrugged again. "Why should it be? Pioneer may not possess any intelligence of her own, but she was created by an intelligence. She's spitting out available data-data we've given her-she's just not doing it in a form we understand."

"Whoa! There's a fourth sequence!" Santiago Rodriguez's voice, quiet as it was, cut through the discussion taking place over his head. The silence was immediate and thick.

"First five figures, the same . . . then 96.9, 124.4, 95.7."

Kurt leaned in to look at the series of numbers now lining up across the screen. "Okay, now the end of the sequence is completely different. The only thing obviously common is that the seventh figure is always larger than the others."

"You think we'll see that same pattern in the next sequence?" asked Grace.

"If there is a next sequence," said Santiago.

There was. It began as they all began, but the last three digits were 96, 122.5, 96. Not one of them matched a previously sent number. New sequences of numbers continued to come in-thirty unique sequences in all. Then there was a pause and they began to repeat, beginning with the initial sequence, and replaying in exactly the same order as they were originally received. Occasionally, there was a repeated digit, but there seemed to be no pattern. When it became clear that no new sequences were going to appear, Kurt called an a.n.a.lysis session.

While machine intelligences compared numbers, biological intelligences mulled patterns in their own way. They considered spatial coordinates, global coordinates, geometric figures.

"The second, third, and fourth numbers form a square," said Santiago, doodling on the white board in the conference room. He used a scale of one-half inch per unit, so the figure would fit on the board. "And the last three numbers could be the sides of a triangle."

"What about the first figure?" asked Gita. "What do you make of that? A line?"

Santiago drew a line 30.3 inches in length. "Yeah. Maybe . . . maybe that's it-a line between two points, then a figure with three points, then a four sided figure."

"Except," said Grace, "that they didn't arrive in that order. They came one, four, three."

"Maybe 18.9 is the diameter of a circle," suggested Gita. "Or the circ.u.mference. They could be showing us that they understand geometric constructs."

"They?" repeated Grace.

Gita flushed. "Did I really say that?" She shook her head. "Too many episodes of X-Files. Sorry."

"Hey," Kurt said, "it's why we're here-right, Dr. Grace? But why would the triangle-and only the triangle-vary in size?"

The question was met with silence.

They resorted to computer a.s.sistance at that point, generating two different sizes of circles, a square, and a series of thirty triangles-thirty lopsided, irregular triangles. They put the circles inside the squares, and the squares inside the triangles, oriented them in numerous ways. Nothing rang a bell, for either human or machine. In the end they sat back, mentally exhausted, and stared at the pages taped to the walls of the conference room-circles, squares, and/or triangles on every one.

"All right," said Kurt. "It's geometry. But why the subtle differences? Why such regularity in the first set of numbers and such irregularity in the second? And why the oddball matches? They've got to be significant."

"Do they?" asked Santiago. "If this is Pioneer spinning dreams or having the machine equivalent of a near death experience, then maybe the variations are merely extrapolations on a program they created for a First Contact scenario."

Gita shook her head. "They didn't program a geometry set like that into Pioneer. Roz and I went over every one of the First Contact protocols. There's nothing like this anywhere in her routines. Besides, Pioneer can't extrapolate. She's a machine. An old machine. A dying machine."

"Look," said Kurt, rubbing his forehead, "let's a.s.sume for a moment that Pioneer is merely expiring much later than expected and that for whatever reason she went off on her own, scrambled a bunch of old messages and sent them home. Let's a.s.sume that she refused to respond to familiar command sequences because they no longer seemed familiar. That she responded to an echo of her own unprovoked transmission because it did seem familiar. And let's further a.s.sume that receiving that echo caused her to randomly change the second set of numbers in what is now her default data set. Let's also a.s.sume that these numbers are dimensions for geometric shapes. What should our response be?"

"Why respond at all?" asked Gita. "That's what our friend from NASA would say. If this is Pioneer, the only significance is that she seems to have resurrected herself."

"Like Quetzalcoatl?" murmured Santiago.

Gita's dark brows arced gracefully. "Exactly. Score one for old rocket scientists. But if that's the case, there is no intrinsic significance to her message, above the incredible fact that she was able to send it at all. Any return messages we send should be targeted to keeping her online as long as possible, maybe getting her to return to an old routine, send some real data."

"I hear a definite 'but,' " said Kurt.

"But . . . if this isn't Pioneer, then this message is more significant than we can possibly imagine and our response should be targeted to letting whoever programmed that message know we got it and understand what we got."

"They already know we got it," said Santiago. "If there is a 'they.' And we don't understand it completely."

Gita ground the heel of her hand into her forehead. "But isn't that enough? Can't we send some geometry of our own?"

"Let's work on it," Kurt said. "Tomorrow, when I don't feel so much like a zombie. Let's sleep on it. Maybe one of us will have an epiphany."

If there were no epiphanies to be had in Puerto Rico that night, there was at least a piece of one in British Columbia. It came during the ten o'clock news in a living room in the town of Chilliwack.

The man had half risen from the sofa, mentally already in bed when the story about messages from s.p.a.ce caught his attention and the numbers being scrolled out across the screen, his curiosity.

He sat back down.

Four orderly rows of figures later, he reached for a steno pad, flipped to a page devoid of Scrabble scores and wrote the numbers down. In the end, his pad contained thirty rows of eight figures each.

18.9, 27.44, 27.44, 27.44, 27.44, 103.6, 121.9, 99.1.

18.9, 27.44, 27.44, 27.44, 27.44, 103.6, 134.1, 99.1.

18.9, 27.44, 27.44, 27.44, 27.44, 108.2, 121.9, 107.6.